shell/hush.c

/* vi: set sw=4 ts=4: */
/*
 * A prototype Bourne shell grammar parser.
 * Intended to follow the original Thompson and Ritchie
 * "small and simple is beautiful" philosophy, which
 * incidentally is a good match to today's BusyBox.
 *
 * Copyright (C) 2000,2001  Larry Doolittle <larry@doolittle.boa.org>
 * Copyright (C) 2008,2009  Denys Vlasenko <vda.linux@googlemail.com>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 *
 * Credits:
 *      The parser routines proper are all original material, first
 *      written Dec 2000 and Jan 2001 by Larry Doolittle.  The
 *      execution engine, the builtins, and much of the underlying
 *      support has been adapted from busybox-0.49pre's lash, which is
 *      Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
 *      written by Erik Andersen <andersen@codepoet.org>.  That, in turn,
 *      is based in part on ladsh.c, by Michael K. Johnson and Erik W.
 *      Troan, which they placed in the public domain.  I don't know
 *      how much of the Johnson/Troan code has survived the repeated
 *      rewrites.
 *
 * Other credits:
 *      o_addchr derived from similar w_addchar function in glibc-2.2.
 *      parse_redirect, redirect_opt_num, and big chunks of main
 *      and many builtins derived from contributions by Erik Andersen.
 *      Miscellaneous bugfixes from Matt Kraai.
 *
 * There are two big (and related) architecture differences between
 * this parser and the lash parser.  One is that this version is
 * actually designed from the ground up to understand nearly all
 * of the Bourne grammar.  The second, consequential change is that
 * the parser and input reader have been turned inside out.  Now,
 * the parser is in control, and asks for input as needed.  The old
 * way had the input reader in control, and it asked for parsing to
 * take place as needed.  The new way makes it much easier to properly
 * handle the recursion implicit in the various substitutions, especially
 * across continuation lines.
 *
 * TODOs:
 *      grep for "TODO" and fix (some of them are easy)
 *      make complex ${var%...} constructs support optional
 *      make here documents optional
 *      special variables (done: PWD, PPID, RANDOM)
 *      follow IFS rules more precisely, including update semantics
 *      tilde expansion
 *      aliases
 *      builtins mandated by standards we don't support:
 *          [un]alias, command, fc:
 *          command -v CMD: print "/path/to/CMD"
 *              prints "CMD" for builtins
 *              prints "alias ALIAS='EXPANSION'" for aliases
 *              prints nothing and sets $? to 1 if not found
 *          command -V CMD: print "CMD is /path/CMD|a shell builtin|etc"
 *          command [-p] CMD: run CMD, even if a function CMD also exists
 *              (can use this to override standalone shell as well)
 *              -p: use default $PATH
 *          command BLTIN: disables special-ness (e.g. errors do not abort)
 *          fc -l[nr] [BEG] [END]: list range of commands in history
 *          fc [-e EDITOR] [BEG] [END]: edit/rerun range of commands
 *          fc -s [PAT=REP] [CMD]: rerun CMD, replacing PAT with REP
 *
 * Bash compat TODO:
 *      redirection of stdout+stderr: &> and >&
 *      reserved words: function select
 *      advanced test: [[ ]]
 *      process substitution: <(list) and >(list)
 *      =~: regex operator
 *      let EXPR [EXPR...]
 *          Each EXPR is an arithmetic expression (ARITHMETIC EVALUATION)
 *          If the last arg evaluates to 0, let returns 1; 0 otherwise.
 *          NB: let `echo 'a=a + 1'` - error (IOW: multi-word expansion is used)
 *      ((EXPR))
 *          The EXPR is evaluated according to ARITHMETIC EVALUATION.
 *          This is exactly equivalent to let "EXPR".
 *      $[EXPR]: synonym for $((EXPR))
 *      indirect expansion: ${!VAR}
 *      substring op on @: ${@:n:m}
 *
 * Won't do:
 *      Some builtins mandated by standards:
 *          newgrp [GRP]: not a builtin in bash but a suid binary
 *              which spawns a new shell with new group ID
 *      In bash, export builtin is special, its arguments are assignments
 *          and therefore expansion of them should be "one-word" expansion:
 *              $ export i=`echo 'a  b'` # export has one arg: "i=a  b"
 *          compare with:
 *              $ ls i=`echo 'a  b'`     # ls has two args: "i=a" and "b"
 *              ls: cannot access i=a: No such file or directory
 *              ls: cannot access b: No such file or directory
 *          Note1: same applies to local builtin.
 *          Note2: bash 3.2.33(1) does this only if export word itself
 *          is not quoted:
 *              $ export i=`echo 'aaa  bbb'`; echo "$i"
 *              aaa  bbb
 *              $ "export" i=`echo 'aaa  bbb'`; echo "$i"
 *              aaa
 */
//config:config HUSH
//config:	bool "hush (64 kb)"
//config:	default y
//config:	help
//config:	hush is a small shell. It handles the normal flow control
//config:	constructs such as if/then/elif/else/fi, for/in/do/done, while loops,
//config:	case/esac. Redirections, here documents, $((arithmetic))
//config:	and functions are supported.
//config:
//config:	It will compile and work on no-mmu systems.
//config:
//config:	It does not handle select, aliases, tilde expansion,
//config:	&>file and >&file redirection of stdout+stderr.
//config:
//config:config HUSH_BASH_COMPAT
//config:	bool "bash-compatible extensions"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_BRACE_EXPANSION
//config:	bool "Brace expansion"
//config:	default y
//config:	depends on HUSH_BASH_COMPAT
//config:	help
//config:	Enable {abc,def} extension.
//config:
//config:config HUSH_INTERACTIVE
//config:	bool "Interactive mode"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:	help
//config:	Enable interactive mode (prompt and command editing).
//config:	Without this, hush simply reads and executes commands
//config:	from stdin just like a shell script from a file.
//config:	No prompt, no PS1/PS2 magic shell variables.
//config:
//config:config HUSH_SAVEHISTORY
//config:	bool "Save command history to .hush_history"
//config:	default y
//config:	depends on HUSH_INTERACTIVE && FEATURE_EDITING_SAVEHISTORY
//config:
//config:config HUSH_JOB
//config:	bool "Job control"
//config:	default y
//config:	depends on HUSH_INTERACTIVE
//config:	help
//config:	Enable job control: Ctrl-Z backgrounds, Ctrl-C interrupts current
//config:	command (not entire shell), fg/bg builtins work. Without this option,
//config:	"cmd &" still works by simply spawning a process and immediately
//config:	prompting for next command (or executing next command in a script),
//config:	but no separate process group is formed.
//config:
//config:config HUSH_TICK
//config:	bool "Support process substitution"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:	help
//config:	Enable `command` and $(command).
//config:
//config:config HUSH_IF
//config:	bool "Support if/then/elif/else/fi"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_LOOPS
//config:	bool "Support for, while and until loops"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_CASE
//config:	bool "Support case ... esac statement"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:	help
//config:	Enable case ... esac statement. +400 bytes.
//config:
//config:config HUSH_FUNCTIONS
//config:	bool "Support funcname() { commands; } syntax"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:	help
//config:	Enable support for shell functions. +800 bytes.
//config:
//config:config HUSH_LOCAL
//config:	bool "local builtin"
//config:	default y
//config:	depends on HUSH_FUNCTIONS
//config:	help
//config:	Enable support for local variables in functions.
//config:
//config:config HUSH_RANDOM_SUPPORT
//config:	bool "Pseudorandom generator and $RANDOM variable"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:	help
//config:	Enable pseudorandom generator and dynamic variable "$RANDOM".
//config:	Each read of "$RANDOM" will generate a new pseudorandom value.
//config:
//config:config HUSH_MODE_X
//config:	bool "Support 'hush -x' option and 'set -x' command"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:	help
//config:	This instructs hush to print commands before execution.
//config:	Adds ~300 bytes.
//config:
//config:config HUSH_ECHO
//config:	bool "echo builtin"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_PRINTF
//config:	bool "printf builtin"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_TEST
//config:	bool "test builtin"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_HELP
//config:	bool "help builtin"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_EXPORT
//config:	bool "export builtin"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_EXPORT_N
//config:	bool "Support 'export -n' option"
//config:	default y
//config:	depends on HUSH_EXPORT
//config:	help
//config:	export -n unexports variables. It is a bash extension.
//config:
//config:config HUSH_READONLY
//config:	bool "readonly builtin"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:	help
//config:	Enable support for read-only variables.
//config:
//config:config HUSH_KILL
//config:	bool "kill builtin (supports kill %jobspec)"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_WAIT
//config:	bool "wait builtin"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_TRAP
//config:	bool "trap builtin"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_TYPE
//config:	bool "type builtin"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_TIMES
//config:	bool "times builtin"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_READ
//config:	bool "read builtin"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_SET
//config:	bool "set builtin"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_UNSET
//config:	bool "unset builtin"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_ULIMIT
//config:	bool "ulimit builtin"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_UMASK
//config:	bool "umask builtin"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_GETOPTS
//config:	bool "getopts builtin"
//config:	default y
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH
//config:
//config:config HUSH_MEMLEAK
//config:	bool "memleak builtin (debugging)"
//config:	default n
//config:	depends on HUSH || SH_IS_HUSH || BASH_IS_HUSH

//applet:IF_HUSH(APPLET(hush, BB_DIR_BIN, BB_SUID_DROP))
//                       APPLET_ODDNAME:name  main  location    suid_type     help
//applet:IF_SH_IS_HUSH(  APPLET_ODDNAME(sh,   hush, BB_DIR_BIN, BB_SUID_DROP, hush))
//applet:IF_BASH_IS_HUSH(APPLET_ODDNAME(bash, hush, BB_DIR_BIN, BB_SUID_DROP, hush))

//kbuild:lib-$(CONFIG_HUSH) += hush.o match.o shell_common.o
//kbuild:lib-$(CONFIG_SH_IS_HUSH) += hush.o match.o shell_common.o
//kbuild:lib-$(CONFIG_BASH_IS_HUSH) += hush.o match.o shell_common.o
//kbuild:lib-$(CONFIG_HUSH_RANDOM_SUPPORT) += random.o

/* -i (interactive) and -s (read stdin) are also accepted,
 * but currently do nothing, therefore aren't shown in help.
 * NOMMU-specific options are not meant to be used by users,
 * therefore we don't show them either.
 */
//usage:#define hush_trivial_usage
//usage:	"[-enxl] [-c 'SCRIPT' [ARG0 [ARGS]] / FILE [ARGS]]"
//usage:#define hush_full_usage "\n\n"
//usage:	"Unix shell interpreter"

#if !(defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__) \
	|| defined(__APPLE__) \
    )
# include <malloc.h>   /* for malloc_trim */
#endif
#include <glob.h>
/* #include <dmalloc.h> */
#if ENABLE_HUSH_CASE
# include <fnmatch.h>
#endif
#include <sys/times.h>
#include <sys/utsname.h> /* for setting $HOSTNAME */

#include "busybox.h"  /* for APPLET_IS_NOFORK/NOEXEC */
#include "unicode.h"
#include "shell_common.h"
#include "math.h"
#include "match.h"
#if ENABLE_HUSH_RANDOM_SUPPORT
# include "random.h"
#else
# define CLEAR_RANDOM_T(rnd) ((void)0)
#endif
#ifndef F_DUPFD_CLOEXEC
# define F_DUPFD_CLOEXEC F_DUPFD
#endif
#ifndef PIPE_BUF
# define PIPE_BUF 4096  /* amount of buffering in a pipe */
#endif


/* So far, all bash compat is controlled by one config option */
/* Separate defines document which part of code implements what */
#define BASH_PATTERN_SUBST ENABLE_HUSH_BASH_COMPAT
#define BASH_SUBSTR        ENABLE_HUSH_BASH_COMPAT
#define BASH_SOURCE        ENABLE_HUSH_BASH_COMPAT
#define BASH_HOSTNAME_VAR  ENABLE_HUSH_BASH_COMPAT
#define BASH_TEST2         (ENABLE_HUSH_BASH_COMPAT && ENABLE_HUSH_TEST)
#define BASH_READ_D        ENABLE_HUSH_BASH_COMPAT


/* Build knobs */
#define LEAK_HUNTING 0
#define BUILD_AS_NOMMU 0
/* Enable/disable sanity checks. Ok to enable in production,
 * only adds a bit of bloat. Set to >1 to get non-production level verbosity.
 * Keeping 1 for now even in released versions.
 */
#define HUSH_DEBUG 1
/* Slightly bigger (+200 bytes), but faster hush.
 * So far it only enables a trick with counting SIGCHLDs and forks,
 * which allows us to do fewer waitpid's.
 * (we can detect a case where neither forks were done nor SIGCHLDs happened
 * and therefore waitpid will return the same result as last time)
 */
#define ENABLE_HUSH_FAST 0
/* TODO: implement simplified code for users which do not need ${var%...} ops
 * So far ${var%...} ops are always enabled:
 */
#define ENABLE_HUSH_DOLLAR_OPS 1


#if BUILD_AS_NOMMU
# undef BB_MMU
# undef USE_FOR_NOMMU
# undef USE_FOR_MMU
# define BB_MMU 0
# define USE_FOR_NOMMU(...) __VA_ARGS__
# define USE_FOR_MMU(...)
#endif

#include "NUM_APPLETS.h"
#if NUM_APPLETS == 1
/* STANDALONE does not make sense, and won't compile */
# undef CONFIG_FEATURE_SH_STANDALONE
# undef ENABLE_FEATURE_SH_STANDALONE
# undef IF_FEATURE_SH_STANDALONE
# undef IF_NOT_FEATURE_SH_STANDALONE
# define ENABLE_FEATURE_SH_STANDALONE 0
# define IF_FEATURE_SH_STANDALONE(...)
# define IF_NOT_FEATURE_SH_STANDALONE(...) __VA_ARGS__
#endif

#if !ENABLE_HUSH_INTERACTIVE
# undef ENABLE_FEATURE_EDITING
# define ENABLE_FEATURE_EDITING 0
# undef ENABLE_FEATURE_EDITING_FANCY_PROMPT
# define ENABLE_FEATURE_EDITING_FANCY_PROMPT 0
# undef ENABLE_FEATURE_EDITING_SAVE_ON_EXIT
# define ENABLE_FEATURE_EDITING_SAVE_ON_EXIT 0
#endif

/* Do we support ANY keywords? */
#if ENABLE_HUSH_IF || ENABLE_HUSH_LOOPS || ENABLE_HUSH_CASE
# define HAS_KEYWORDS 1
# define IF_HAS_KEYWORDS(...) __VA_ARGS__
# define IF_HAS_NO_KEYWORDS(...)
#else
# define HAS_KEYWORDS 0
# define IF_HAS_KEYWORDS(...)
# define IF_HAS_NO_KEYWORDS(...) __VA_ARGS__
#endif

/* If you comment out one of these below, it will be #defined later
 * to perform debug printfs to stderr: */
#define debug_printf(...)        do {} while (0)
/* Finer-grained debug switches */
#define debug_printf_parse(...)  do {} while (0)
#define debug_print_tree(a, b)   do {} while (0)
#define debug_printf_exec(...)   do {} while (0)
#define debug_printf_env(...)    do {} while (0)
#define debug_printf_jobs(...)   do {} while (0)
#define debug_printf_expand(...) do {} while (0)
#define debug_printf_varexp(...) do {} while (0)
#define debug_printf_glob(...)   do {} while (0)
#define debug_printf_redir(...)  do {} while (0)
#define debug_printf_list(...)   do {} while (0)
#define debug_printf_subst(...)  do {} while (0)
#define debug_printf_clean(...)  do {} while (0)

#define ERR_PTR ((void*)(long)1)

#define JOB_STATUS_FORMAT    "[%u] %-22s %.40s\n"

#define _SPECIAL_VARS_STR     "_*@$!?#"
#define SPECIAL_VARS_STR     ("_*@$!?#" + 1)
#define NUMERIC_SPECVARS_STR ("_*@$!?#" + 3)
#if BASH_PATTERN_SUBST
/* Support / and // replace ops */
/* Note that // is stored as \ in "encoded" string representation */
# define VAR_ENCODED_SUBST_OPS      "\\/%#:-=+?"
# define VAR_SUBST_OPS             ("\\/%#:-=+?" + 1)
# define MINUS_PLUS_EQUAL_QUESTION ("\\/%#:-=+?" + 5)
#else
# define VAR_ENCODED_SUBST_OPS      "%#:-=+?"
# define VAR_SUBST_OPS              "%#:-=+?"
# define MINUS_PLUS_EQUAL_QUESTION ("%#:-=+?" + 3)
#endif

#define SPECIAL_VAR_SYMBOL   3

struct variable;

static const char hush_version_str[] ALIGN1 = "HUSH_VERSION="BB_VER;

/* This supports saving pointers malloced in vfork child,
 * to be freed in the parent.
 */
#if !BB_MMU
typedef struct nommu_save_t {
	char **new_env;
	struct variable *old_vars;
	char **argv;
	char **argv_from_re_execing;
} nommu_save_t;
#endif

enum {
	RES_NONE  = 0,
#if ENABLE_HUSH_IF
	RES_IF    ,
	RES_THEN  ,
	RES_ELIF  ,
	RES_ELSE  ,
	RES_FI    ,
#endif
#if ENABLE_HUSH_LOOPS
	RES_FOR   ,
	RES_WHILE ,
	RES_UNTIL ,
	RES_DO    ,
	RES_DONE  ,
#endif
#if ENABLE_HUSH_LOOPS || ENABLE_HUSH_CASE
	RES_IN    ,
#endif
#if ENABLE_HUSH_CASE
	RES_CASE  ,
	/* three pseudo-keywords support contrived "case" syntax: */
	RES_CASE_IN,   /* "case ... IN", turns into RES_MATCH when IN is observed */
	RES_MATCH ,    /* "word)" */
	RES_CASE_BODY, /* "this command is inside CASE" */
	RES_ESAC  ,
#endif
	RES_XXXX  ,
	RES_SNTX
};

typedef struct o_string {
	char *data;
	int length; /* position where data is appended */
	int maxlen;
	int o_expflags;
	/* At least some part of the string was inside '' or "",
	 * possibly empty one: word"", wo''rd etc. */
	smallint has_quoted_part;
	smallint has_empty_slot;
	smallint o_assignment; /* 0:maybe, 1:yes, 2:no */
} o_string;
enum {
	EXP_FLAG_SINGLEWORD     = 0x80, /* must be 0x80 */
	EXP_FLAG_GLOB           = 0x2,
	/* Protect newly added chars against globbing
	 * by prepending \ to *, ?, [, \ */
	EXP_FLAG_ESC_GLOB_CHARS = 0x1,
};
enum {
	MAYBE_ASSIGNMENT      = 0,
	DEFINITELY_ASSIGNMENT = 1,
	NOT_ASSIGNMENT        = 2,
	/* Not an assignment, but next word may be: "if v=xyz cmd;" */
	WORD_IS_KEYWORD       = 3,
};
/* Used for initialization: o_string foo = NULL_O_STRING; */
#define NULL_O_STRING { NULL }

#ifndef debug_printf_parse
static const char *const assignment_flag[] = {
	"MAYBE_ASSIGNMENT",
	"DEFINITELY_ASSIGNMENT",
	"NOT_ASSIGNMENT",
	"WORD_IS_KEYWORD",
};
#endif

typedef struct in_str {
	const char *p;
#if ENABLE_HUSH_INTERACTIVE
	smallint promptmode; /* 0: PS1, 1: PS2 */
#endif
	int peek_buf[2];
	int last_char;
	FILE *file;
} in_str;

/* The descrip member of this structure is only used to make
 * debugging output pretty */
static const struct {
	int mode;
	signed char default_fd;
	char descrip[3];
} redir_table[] = {
	{ O_RDONLY,                  0, "<"  },
	{ O_CREAT|O_TRUNC|O_WRONLY,  1, ">"  },
	{ O_CREAT|O_APPEND|O_WRONLY, 1, ">>" },
	{ O_CREAT|O_RDWR,            1, "<>" },
	{ O_RDONLY,                  0, "<<" },
/* Should not be needed. Bogus default_fd helps in debugging */
/*	{ O_RDONLY,                 77, "<<" }, */
};

struct redir_struct {
	struct redir_struct *next;
	char *rd_filename;          /* filename */
	int rd_fd;                  /* fd to redirect */
	/* fd to redirect to, or -3 if rd_fd is to be closed (n>&-) */
	int rd_dup;
	smallint rd_type;           /* (enum redir_type) */
	/* note: for heredocs, rd_filename contains heredoc delimiter,
	 * and subsequently heredoc itself; and rd_dup is a bitmask:
	 * bit 0: do we need to trim leading tabs?
	 * bit 1: is heredoc quoted (<<'delim' syntax) ?
	 */
};
typedef enum redir_type {
	REDIRECT_INPUT     = 0,
	REDIRECT_OVERWRITE = 1,
	REDIRECT_APPEND    = 2,
	REDIRECT_IO        = 3,
	REDIRECT_HEREDOC   = 4,
	REDIRECT_HEREDOC2  = 5, /* REDIRECT_HEREDOC after heredoc is loaded */

	REDIRFD_CLOSE      = -3,
	REDIRFD_SYNTAX_ERR = -2,
	REDIRFD_TO_FILE    = -1,
	/* otherwise, rd_fd is redirected to rd_dup */

	HEREDOC_SKIPTABS = 1,
	HEREDOC_QUOTED   = 2,
} redir_type;


struct command {
	pid_t pid;                  /* 0 if exited */
	int assignment_cnt;         /* how many argv[i] are assignments? */
	smallint cmd_type;          /* CMD_xxx */
#define CMD_NORMAL   0
#define CMD_SUBSHELL 1
#if BASH_TEST2
/* used for "[[ EXPR ]]" */
# define CMD_SINGLEWORD_NOGLOB 2
#endif
#if ENABLE_HUSH_FUNCTIONS
# define CMD_FUNCDEF 3
#endif

	smalluint cmd_exitcode;
	/* if non-NULL, this "command" is { list }, ( list ), or a compound statement */
	struct pipe *group;
#if !BB_MMU
	char *group_as_string;
#endif
#if ENABLE_HUSH_FUNCTIONS
	struct function *child_func;
/* This field is used to prevent a bug here:
 * while...do f1() {a;}; f1; f1() {b;}; f1; done
 * When we execute "f1() {a;}" cmd, we create new function and clear
 * cmd->group, cmd->group_as_string, cmd->argv[0].
 * When we execute "f1() {b;}", we notice that f1 exists,
 * and that its "parent cmd" struct is still "alive",
 * we put those fields back into cmd->xxx
 * (struct function has ->parent_cmd ptr to facilitate that).
 * When we loop back, we can execute "f1() {a;}" again and set f1 correctly.
 * Without this trick, loop would execute a;b;b;b;...
 * instead of correct sequence a;b;a;b;...
 * When command is freed, it severs the link
 * (sets ->child_func->parent_cmd to NULL).
 */
#endif
	char **argv;                /* command name and arguments */
/* argv vector may contain variable references (^Cvar^C, ^C0^C etc)
 * and on execution these are substituted with their values.
 * Substitution can make _several_ words out of one argv[n]!
 * Example: argv[0]=='.^C*^C.' here: echo .$*.
 * References of the form ^C`cmd arg^C are `cmd arg` substitutions.
 */
	struct redir_struct *redirects; /* I/O redirections */
};
/* Is there anything in this command at all? */
#define IS_NULL_CMD(cmd) \
	(!(cmd)->group && !(cmd)->argv && !(cmd)->redirects)

struct pipe {
	struct pipe *next;
	int num_cmds;               /* total number of commands in pipe */
	int alive_cmds;             /* number of commands running (not exited) */
	int stopped_cmds;           /* number of commands alive, but stopped */
#if ENABLE_HUSH_JOB
	unsigned jobid;             /* job number */
	pid_t pgrp;                 /* process group ID for the job */
	char *cmdtext;              /* name of job */
#endif
	struct command *cmds;       /* array of commands in pipe */
	smallint followup;          /* PIPE_BG, PIPE_SEQ, PIPE_OR, PIPE_AND */
	IF_HAS_KEYWORDS(smallint pi_inverted;) /* "! cmd | cmd" */
	IF_HAS_KEYWORDS(smallint res_word;) /* needed for if, for, while, until... */
};
typedef enum pipe_style {
	PIPE_SEQ = 0,
	PIPE_AND = 1,
	PIPE_OR  = 2,
	PIPE_BG  = 3,
} pipe_style;
/* Is there anything in this pipe at all? */
#define IS_NULL_PIPE(pi) \
	((pi)->num_cmds == 0 IF_HAS_KEYWORDS( && (pi)->res_word == RES_NONE))

/* This holds pointers to the various results of parsing */
struct parse_context {
	/* linked list of pipes */
	struct pipe *list_head;
	/* last pipe (being constructed right now) */
	struct pipe *pipe;
	/* last command in pipe (being constructed right now) */
	struct command *command;
	/* last redirect in command->redirects list */
	struct redir_struct *pending_redirect;
#if !BB_MMU
	o_string as_string;
#endif
#if HAS_KEYWORDS
	smallint ctx_res_w;
	smallint ctx_inverted; /* "! cmd | cmd" */
#if ENABLE_HUSH_CASE
	smallint ctx_dsemicolon; /* ";;" seen */
#endif
	/* bitmask of FLAG_xxx, for figuring out valid reserved words */
	int old_flag;
	/* group we are enclosed in:
	 * example: "if pipe1; pipe2; then pipe3; fi"
	 * when we see "if" or "then", we malloc and copy current context,
	 * and make ->stack point to it. then we parse pipeN.
	 * when closing "then" / fi" / whatever is found,
	 * we move list_head into ->stack->command->group,
	 * copy ->stack into current context, and delete ->stack.
	 * (parsing of { list } and ( list ) doesn't use this method)
	 */
	struct parse_context *stack;
#endif
};

/* On program start, environ points to initial environment.
 * putenv adds new pointers into it, unsetenv removes them.
 * Neither of these (de)allocates the strings.
 * setenv allocates new strings in malloc space and does putenv,
 * and thus setenv is unusable (leaky) for shell's purposes */
#define setenv(...) setenv_is_leaky_dont_use()
struct variable {
	struct variable *next;
	char *varstr;        /* points to "name=" portion */
#if ENABLE_HUSH_LOCAL
	unsigned func_nest_level;
#endif
	int max_len;         /* if > 0, name is part of initial env; else name is malloced */
	smallint flg_export; /* putenv should be done on this var */
	smallint flg_read_only;
};

enum {
	BC_BREAK = 1,
	BC_CONTINUE = 2,
};

#if ENABLE_HUSH_FUNCTIONS
struct function {
	struct function *next;
	char *name;
	struct command *parent_cmd;
	struct pipe *body;
# if !BB_MMU
	char *body_as_string;
# endif
};
#endif


/* set -/+o OPT support. (TODO: make it optional)
 * bash supports the following opts:
 * allexport       off
 * braceexpand     on
 * emacs           on
 * errexit         off
 * errtrace        off
 * functrace       off
 * hashall         on
 * histexpand      off
 * history         on
 * ignoreeof       off
 * interactive-comments    on
 * keyword         off
 * monitor         on
 * noclobber       off
 * noexec          off
 * noglob          off
 * nolog           off
 * notify          off
 * nounset         off
 * onecmd          off
 * physical        off
 * pipefail        off
 * posix           off
 * privileged      off
 * verbose         off
 * vi              off
 * xtrace          off
 */
static const char o_opt_strings[] ALIGN1 =
	"pipefail\0"
	"noexec\0"
	"errexit\0"
#if ENABLE_HUSH_MODE_X
	"xtrace\0"
#endif
	;
enum {
	OPT_O_PIPEFAIL,
	OPT_O_NOEXEC,
	OPT_O_ERREXIT,
#if ENABLE_HUSH_MODE_X
	OPT_O_XTRACE,
#endif
	NUM_OPT_O
};


struct FILE_list {
	struct FILE_list *next;
	FILE *fp;
	int fd;
};


/* "Globals" within this file */
/* Sorted roughly by size (smaller offsets == smaller code) */
struct globals {
	/* interactive_fd != 0 means we are an interactive shell.
	 * If we are, then saved_tty_pgrp can also be != 0, meaning
	 * that controlling tty is available. With saved_tty_pgrp == 0,
	 * job control still works, but terminal signals
	 * (^C, ^Z, ^Y, ^\) won't work at all, and background
	 * process groups can only be created with "cmd &".
	 * With saved_tty_pgrp != 0, hush will use tcsetpgrp()
	 * to give tty to the foreground process group,
	 * and will take it back when the group is stopped (^Z)
	 * or killed (^C).
	 */
#if ENABLE_HUSH_INTERACTIVE
	/* 'interactive_fd' is a fd# open to ctty, if we have one
	 * _AND_ if we decided to act interactively */
	int interactive_fd;
	const char *PS1;
	const char *PS2;
# define G_interactive_fd (G.interactive_fd)
#else
# define G_interactive_fd 0
#endif
#if ENABLE_FEATURE_EDITING
	line_input_t *line_input_state;
#endif
	pid_t root_pid;
	pid_t root_ppid;
	pid_t last_bg_pid;
#if ENABLE_HUSH_RANDOM_SUPPORT
	random_t random_gen;
#endif
#if ENABLE_HUSH_JOB
	int run_list_level;
	unsigned last_jobid;
	pid_t saved_tty_pgrp;
	struct pipe *job_list;
# define G_saved_tty_pgrp (G.saved_tty_pgrp)
#else
# define G_saved_tty_pgrp 0
#endif
	/* How deeply are we in context where "set -e" is ignored */
	int errexit_depth;
	/* "set -e" rules (do we follow them correctly?):
	 * Exit if pipe, list, or compound command exits with a non-zero status.
	 * Shell does not exit if failed command is part of condition in
	 * if/while, part of && or || list except the last command, any command
	 * in a pipe but the last, or if the command's return value is being
	 * inverted with !. If a compound command other than a subshell returns a
	 * non-zero status because a command failed while -e was being ignored, the
	 * shell does not exit. A trap on ERR, if set, is executed before the shell
	 * exits [ERR is a bashism].
	 *
	 * If a compound command or function executes in a context where -e is
	 * ignored, none of the commands executed within are affected by the -e
	 * setting. If a compound command or function sets -e while executing in a
	 * context where -e is ignored, that setting does not have any effect until
	 * the compound command or the command containing the function call completes.
	 */

	char o_opt[NUM_OPT_O];
#if ENABLE_HUSH_MODE_X
# define G_x_mode (G.o_opt[OPT_O_XTRACE])
#else
# define G_x_mode 0
#endif
	smallint flag_SIGINT;
#if ENABLE_HUSH_LOOPS
	smallint flag_break_continue;
#endif
#if ENABLE_HUSH_FUNCTIONS
	/* 0: outside of a function (or sourced file)
	 * -1: inside of a function, ok to use return builtin
	 * 1: return is invoked, skip all till end of func
	 */
	smallint flag_return_in_progress;
# define G_flag_return_in_progress (G.flag_return_in_progress)
#else
# define G_flag_return_in_progress 0
#endif
	smallint exiting; /* used to prevent EXIT trap recursion */
	/* These four support $?, $#, and $1 */
	smalluint last_exitcode;
	smalluint last_bg_pid_exitcode;
#if ENABLE_HUSH_SET
	/* are global_argv and global_argv[1..n] malloced? (note: not [0]) */
	smalluint global_args_malloced;
# define G_global_args_malloced (G.global_args_malloced)
#else
# define G_global_args_malloced 0
#endif
	/* how many non-NULL argv's we have. NB: $# + 1 */
	int global_argc;
	char **global_argv;
#if !BB_MMU
	char *argv0_for_re_execing;
#endif
#if ENABLE_HUSH_LOOPS
	unsigned depth_break_continue;
	unsigned depth_of_loop;
#endif
	const char *ifs;
	const char *cwd;
	struct variable *top_var;
	char **expanded_assignments;
#if ENABLE_HUSH_FUNCTIONS
	struct function *top_func;
# if ENABLE_HUSH_LOCAL
	struct variable **shadowed_vars_pp;
	unsigned func_nest_level;
# endif
#endif
	/* Signal and trap handling */
#if ENABLE_HUSH_FAST
	unsigned count_SIGCHLD;
	unsigned handled_SIGCHLD;
	smallint we_have_children;
#endif
	struct FILE_list *FILE_list;
	/* Which signals have non-DFL handler (even with no traps set)?
	 * Set at the start to:
	 * (SIGQUIT + maybe SPECIAL_INTERACTIVE_SIGS + maybe SPECIAL_JOBSTOP_SIGS)
	 * SPECIAL_INTERACTIVE_SIGS are cleared after fork.
	 * The rest is cleared right before execv syscalls.
	 * Other than these two times, never modified.
	 */
	unsigned special_sig_mask;
#if ENABLE_HUSH_JOB
	unsigned fatal_sig_mask;
# define G_fatal_sig_mask (G.fatal_sig_mask)
#else
# define G_fatal_sig_mask 0
#endif
#if ENABLE_HUSH_TRAP
	char **traps; /* char *traps[NSIG] */
# define G_traps G.traps
#else
# define G_traps ((char**)NULL)
#endif
	sigset_t pending_set;
#if ENABLE_HUSH_MEMLEAK
	unsigned long memleak_value;
#endif
#if HUSH_DEBUG
	int debug_indent;
#endif
	struct sigaction sa;
#if ENABLE_FEATURE_EDITING
	char user_input_buf[CONFIG_FEATURE_EDITING_MAX_LEN];
#endif
};
#define G (*ptr_to_globals)
/* Not #defining name to G.name - this quickly gets unwieldy
 * (too many defines). Also, I actually prefer to see when a variable
 * is global, thus "G." prefix is a useful hint */
#define INIT_G() do { \
	SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
	/* memset(&G.sa, 0, sizeof(G.sa)); */  \
	sigfillset(&G.sa.sa_mask); \
	G.sa.sa_flags = SA_RESTART; \
} while (0)


/* Function prototypes for builtins */
static int builtin_cd(char **argv) FAST_FUNC;
#if ENABLE_HUSH_ECHO
static int builtin_echo(char **argv) FAST_FUNC;
#endif
static int builtin_eval(char **argv) FAST_FUNC;
static int builtin_exec(char **argv) FAST_FUNC;
static int builtin_exit(char **argv) FAST_FUNC;
#if ENABLE_HUSH_EXPORT
static int builtin_export(char **argv) FAST_FUNC;
#endif
#if ENABLE_HUSH_READONLY
static int builtin_readonly(char **argv) FAST_FUNC;
#endif
#if ENABLE_HUSH_JOB
static int builtin_fg_bg(char **argv) FAST_FUNC;
static int builtin_jobs(char **argv) FAST_FUNC;
#endif
#if ENABLE_HUSH_GETOPTS
static int builtin_getopts(char **argv) FAST_FUNC;
#endif
#if ENABLE_HUSH_HELP
static int builtin_help(char **argv) FAST_FUNC;
#endif
#if MAX_HISTORY && ENABLE_FEATURE_EDITING
static int builtin_history(char **argv) FAST_FUNC;
#endif
#if ENABLE_HUSH_LOCAL
static int builtin_local(char **argv) FAST_FUNC;
#endif
#if ENABLE_HUSH_MEMLEAK
static int builtin_memleak(char **argv) FAST_FUNC;
#endif
#if ENABLE_HUSH_PRINTF
static int builtin_printf(char **argv) FAST_FUNC;
#endif
static int builtin_pwd(char **argv) FAST_FUNC;
#if ENABLE_HUSH_READ
static int builtin_read(char **argv) FAST_FUNC;
#endif
#if ENABLE_HUSH_SET
static int builtin_set(char **argv) FAST_FUNC;
#endif
static int builtin_shift(char **argv) FAST_FUNC;
static int builtin_source(char **argv) FAST_FUNC;
#if ENABLE_HUSH_TEST || BASH_TEST2
static int builtin_test(char **argv) FAST_FUNC;
#endif
#if ENABLE_HUSH_TRAP
static int builtin_trap(char **argv) FAST_FUNC;
#endif
#if ENABLE_HUSH_TYPE
static int builtin_type(char **argv) FAST_FUNC;
#endif
#if ENABLE_HUSH_TIMES
static int builtin_times(char **argv) FAST_FUNC;
#endif
static int builtin_true(char **argv) FAST_FUNC;
#if ENABLE_HUSH_UMASK
static int builtin_umask(char **argv) FAST_FUNC;
#endif
#if ENABLE_HUSH_UNSET
static int builtin_unset(char **argv) FAST_FUNC;
#endif
#if ENABLE_HUSH_KILL
static int builtin_kill(char **argv) FAST_FUNC;
#endif
#if ENABLE_HUSH_WAIT
static int builtin_wait(char **argv) FAST_FUNC;
#endif
#if ENABLE_HUSH_LOOPS
static int builtin_break(char **argv) FAST_FUNC;
static int builtin_continue(char **argv) FAST_FUNC;
#endif
#if ENABLE_HUSH_FUNCTIONS
static int builtin_return(char **argv) FAST_FUNC;
#endif

/* Table of built-in functions.  They can be forked or not, depending on
 * context: within pipes, they fork.  As simple commands, they do not.
 * When used in non-forking context, they can change global variables
 * in the parent shell process.  If forked, of course they cannot.
 * For example, 'unset foo | whatever' will parse and run, but foo will
 * still be set at the end. */
struct built_in_command {
	const char *b_cmd;
	int (*b_function)(char **argv) FAST_FUNC;
#if ENABLE_HUSH_HELP
	const char *b_descr;
# define BLTIN(cmd, func, help) { cmd, func, help }
#else
# define BLTIN(cmd, func, help) { cmd, func }
#endif
};

static const struct built_in_command bltins1[] = {
	BLTIN("."        , builtin_source  , "Run commands in file"),
	BLTIN(":"        , builtin_true    , NULL),
#if ENABLE_HUSH_JOB
	BLTIN("bg"       , builtin_fg_bg   , "Resume job in background"),
#endif
#if ENABLE_HUSH_LOOPS
	BLTIN("break"    , builtin_break   , "Exit loop"),
#endif
	BLTIN("cd"       , builtin_cd      , "Change directory"),
#if ENABLE_HUSH_LOOPS
	BLTIN("continue" , builtin_continue, "Start new loop iteration"),
#endif
	BLTIN("eval"     , builtin_eval    , "Construct and run shell command"),
	BLTIN("exec"     , builtin_exec    , "Execute command, don't return to shell"),
	BLTIN("exit"     , builtin_exit    , NULL),
#if ENABLE_HUSH_EXPORT
	BLTIN("export"   , builtin_export  , "Set environment variables"),
#endif
#if ENABLE_HUSH_JOB
	BLTIN("fg"       , builtin_fg_bg   , "Bring job to foreground"),
#endif
#if ENABLE_HUSH_GETOPTS
	BLTIN("getopts"  , builtin_getopts , NULL),
#endif
#if ENABLE_HUSH_HELP
	BLTIN("help"     , builtin_help    , NULL),
#endif
#if MAX_HISTORY && ENABLE_FEATURE_EDITING
	BLTIN("history"  , builtin_history , "Show history"),
#endif
#if ENABLE_HUSH_JOB
	BLTIN("jobs"     , builtin_jobs    , "List jobs"),
#endif
#if ENABLE_HUSH_KILL
	BLTIN("kill"     , builtin_kill    , "Send signals to processes"),
#endif
#if ENABLE_HUSH_LOCAL
	BLTIN("local"    , builtin_local   , "Set local variables"),
#endif
#if ENABLE_HUSH_MEMLEAK
	BLTIN("memleak"  , builtin_memleak , NULL),
#endif
#if ENABLE_HUSH_READ
	BLTIN("read"     , builtin_read    , "Input into variable"),
#endif
#if ENABLE_HUSH_READONLY
	BLTIN("readonly" , builtin_readonly, "Make variables read-only"),
#endif
#if ENABLE_HUSH_FUNCTIONS
	BLTIN("return"   , builtin_return  , "Return from function"),
#endif
#if ENABLE_HUSH_SET
	BLTIN("set"      , builtin_set     , "Set positional parameters"),
#endif
	BLTIN("shift"    , builtin_shift   , "Shift positional parameters"),
#if BASH_SOURCE
	BLTIN("source"   , builtin_source  , NULL),
#endif
#if ENABLE_HUSH_TIMES
	BLTIN("times"    , builtin_times   , NULL),
#endif
#if ENABLE_HUSH_TRAP
	BLTIN("trap"     , builtin_trap    , "Trap signals"),
#endif
	BLTIN("true"     , builtin_true    , NULL),
#if ENABLE_HUSH_TYPE
	BLTIN("type"     , builtin_type    , "Show command type"),
#endif
#if ENABLE_HUSH_ULIMIT
	BLTIN("ulimit"   , shell_builtin_ulimit, "Control resource limits"),
#endif
#if ENABLE_HUSH_UMASK
	BLTIN("umask"    , builtin_umask   , "Set file creation mask"),
#endif
#if ENABLE_HUSH_UNSET
	BLTIN("unset"    , builtin_unset   , "Unset variables"),
#endif
#if ENABLE_HUSH_WAIT
	BLTIN("wait"     , builtin_wait    , "Wait for process to finish"),
#endif
};
/* These builtins won't be used if we are on NOMMU and need to re-exec
 * (it's cheaper to run an external program in this case):
 */
static const struct built_in_command bltins2[] = {
#if ENABLE_HUSH_TEST
	BLTIN("["        , builtin_test    , NULL),
#endif
#if BASH_TEST2
	BLTIN("[["       , builtin_test    , NULL),
#endif
#if ENABLE_HUSH_ECHO
	BLTIN("echo"     , builtin_echo    , NULL),
#endif
#if ENABLE_HUSH_PRINTF
	BLTIN("printf"   , builtin_printf  , NULL),
#endif
	BLTIN("pwd"      , builtin_pwd     , NULL),
#if ENABLE_HUSH_TEST
	BLTIN("test"     , builtin_test    , NULL),
#endif
};


/* Debug printouts.
 */
#if HUSH_DEBUG
/* prevent disasters with G.debug_indent < 0 */
# define indent() fdprintf(2, "%*s", (G.debug_indent * 2) & 0xff, "")
# define debug_enter() (G.debug_indent++)
# define debug_leave() (G.debug_indent--)
#else
# define indent()      ((void)0)
# define debug_enter() ((void)0)
# define debug_leave() ((void)0)
#endif

#ifndef debug_printf
# define debug_printf(...) (indent(), fdprintf(2, __VA_ARGS__))
#endif

#ifndef debug_printf_parse
# define debug_printf_parse(...) (indent(), fdprintf(2, __VA_ARGS__))
#endif

#ifndef debug_printf_exec
#define debug_printf_exec(...) (indent(), fdprintf(2, __VA_ARGS__))
#endif

#ifndef debug_printf_env
# define debug_printf_env(...) (indent(), fdprintf(2, __VA_ARGS__))
#endif

#ifndef debug_printf_jobs
# define debug_printf_jobs(...) (indent(), fdprintf(2, __VA_ARGS__))
# define DEBUG_JOBS 1
#else
# define DEBUG_JOBS 0
#endif

#ifndef debug_printf_expand
# define debug_printf_expand(...) (indent(), fdprintf(2, __VA_ARGS__))
# define DEBUG_EXPAND 1
#else
# define DEBUG_EXPAND 0
#endif

#ifndef debug_printf_varexp
# define debug_printf_varexp(...) (indent(), fdprintf(2, __VA_ARGS__))
#endif

#ifndef debug_printf_glob
# define debug_printf_glob(...) (indent(), fdprintf(2, __VA_ARGS__))
# define DEBUG_GLOB 1
#else
# define DEBUG_GLOB 0
#endif

#ifndef debug_printf_redir
# define debug_printf_redir(...) (indent(), fdprintf(2, __VA_ARGS__))
#endif

#ifndef debug_printf_list
# define debug_printf_list(...) (indent(), fdprintf(2, __VA_ARGS__))
#endif

#ifndef debug_printf_subst
# define debug_printf_subst(...) (indent(), fdprintf(2, __VA_ARGS__))
#endif

#ifndef debug_printf_clean
# define debug_printf_clean(...) (indent(), fdprintf(2, __VA_ARGS__))
# define DEBUG_CLEAN 1
#else
# define DEBUG_CLEAN 0
#endif

#if DEBUG_EXPAND
static void debug_print_strings(const char *prefix, char **vv)
{
	indent();
	fdprintf(2, "%s:\n", prefix);
	while (*vv)
		fdprintf(2, " '%s'\n", *vv++);
}
#else
# define debug_print_strings(prefix, vv) ((void)0)
#endif


/* Leak hunting. Use hush_leaktool.sh for post-processing.
 */
#if LEAK_HUNTING
static void *xxmalloc(int lineno, size_t size)
{
	void *ptr = xmalloc((size + 0xff) & ~0xff);
	fdprintf(2, "line %d: malloc %p\n", lineno, ptr);
	return ptr;
}
static void *xxrealloc(int lineno, void *ptr, size_t size)
{
	ptr = xrealloc(ptr, (size + 0xff) & ~0xff);
	fdprintf(2, "line %d: realloc %p\n", lineno, ptr);
	return ptr;
}
static char *xxstrdup(int lineno, const char *str)
{
	char *ptr = xstrdup(str);
	fdprintf(2, "line %d: strdup %p\n", lineno, ptr);
	return ptr;
}
static void xxfree(void *ptr)
{
	fdprintf(2, "free %p\n", ptr);
	free(ptr);
}
# define xmalloc(s)     xxmalloc(__LINE__, s)
# define xrealloc(p, s) xxrealloc(__LINE__, p, s)
# define xstrdup(s)     xxstrdup(__LINE__, s)
# define free(p)        xxfree(p)
#endif


/* Syntax and runtime errors. They always abort scripts.
 * In interactive use they usually discard unparsed and/or unexecuted commands
 * and return to the prompt.
 * HUSH_DEBUG >= 2 prints line number in this file where it was detected.
 */
#if HUSH_DEBUG < 2
# define msg_and_die_if_script(lineno, ...)     msg_and_die_if_script(__VA_ARGS__)
# define syntax_error(lineno, msg)              syntax_error(msg)
# define syntax_error_at(lineno, msg)           syntax_error_at(msg)
# define syntax_error_unterm_ch(lineno, ch)     syntax_error_unterm_ch(ch)
# define syntax_error_unterm_str(lineno, s)     syntax_error_unterm_str(s)
# define syntax_error_unexpected_ch(lineno, ch) syntax_error_unexpected_ch(ch)
#endif

static void die_if_script(void)
{
	if (!G_interactive_fd) {
		if (G.last_exitcode) /* sometines it's 2, not 1 (bash compat) */
			xfunc_error_retval = G.last_exitcode;
		xfunc_die();
	}
}

static void msg_and_die_if_script(unsigned lineno, const char *fmt, ...)
{
	va_list p;

#if HUSH_DEBUG >= 2
	bb_error_msg("hush.c:%u", lineno);
#endif
	va_start(p, fmt);
	bb_verror_msg(fmt, p, NULL);
	va_end(p);
	die_if_script();
}

static void syntax_error(unsigned lineno UNUSED_PARAM, const char *msg)
{
	if (msg)
		bb_error_msg("syntax error: %s", msg);
	else
		bb_error_msg("syntax error");
	die_if_script();
}

static void syntax_error_at(unsigned lineno UNUSED_PARAM, const char *msg)
{
	bb_error_msg("syntax error at '%s'", msg);
	die_if_script();
}

static void syntax_error_unterm_str(unsigned lineno UNUSED_PARAM, const char *s)
{
	bb_error_msg("syntax error: unterminated %s", s);
//? source4.tests fails: in bash, echo ${^} in script does not terminate the script
//	die_if_script();
}

static void syntax_error_unterm_ch(unsigned lineno, char ch)
{
	char msg[2] = { ch, '\0' };
	syntax_error_unterm_str(lineno, msg);
}

static void syntax_error_unexpected_ch(unsigned lineno UNUSED_PARAM, int ch)
{
	char msg[2];
	msg[0] = ch;
	msg[1] = '\0';
#if HUSH_DEBUG >= 2
	bb_error_msg("hush.c:%u", lineno);
#endif
	bb_error_msg("syntax error: unexpected %s", ch == EOF ? "EOF" : msg);
	die_if_script();
}

#if HUSH_DEBUG < 2
# undef msg_and_die_if_script
# undef syntax_error
# undef syntax_error_at
# undef syntax_error_unterm_ch
# undef syntax_error_unterm_str
# undef syntax_error_unexpected_ch
#else
# define msg_and_die_if_script(...)     msg_and_die_if_script(__LINE__, __VA_ARGS__)
# define syntax_error(msg)              syntax_error(__LINE__, msg)
# define syntax_error_at(msg)           syntax_error_at(__LINE__, msg)
# define syntax_error_unterm_ch(ch)     syntax_error_unterm_ch(__LINE__, ch)
# define syntax_error_unterm_str(s)     syntax_error_unterm_str(__LINE__, s)
# define syntax_error_unexpected_ch(ch) syntax_error_unexpected_ch(__LINE__, ch)
#endif


#if ENABLE_HUSH_INTERACTIVE
static void cmdedit_update_prompt(void);
#else
# define cmdedit_update_prompt() ((void)0)
#endif


/* Utility functions
 */
/* Replace each \x with x in place, return ptr past NUL. */
static char *unbackslash(char *src)
{
	char *dst = src = strchrnul(src, '\\');
	while (1) {
		if (*src == '\\')
			src++;
		if ((*dst++ = *src++) == '\0')
			break;
	}
	return dst;
}

static char **add_strings_to_strings(char **strings, char **add, int need_to_dup)
{
	int i;
	unsigned count1;
	unsigned count2;
	char **v;

	v = strings;
	count1 = 0;
	if (v) {
		while (*v) {
			count1++;
			v++;
		}
	}
	count2 = 0;
	v = add;
	while (*v) {
		count2++;
		v++;
	}
	v = xrealloc(strings, (count1 + count2 + 1) * sizeof(char*));
	v[count1 + count2] = NULL;
	i = count2;
	while (--i >= 0)
		v[count1 + i] = (need_to_dup ? xstrdup(add[i]) : add[i]);
	return v;
}
#if LEAK_HUNTING
static char **xx_add_strings_to_strings(int lineno, char **strings, char **add, int need_to_dup)
{
	char **ptr = add_strings_to_strings(strings, add, need_to_dup);
	fdprintf(2, "line %d: add_strings_to_strings %p\n", lineno, ptr);
	return ptr;
}
#define add_strings_to_strings(strings, add, need_to_dup) \
	xx_add_strings_to_strings(__LINE__, strings, add, need_to_dup)
#endif

/* Note: takes ownership of "add" ptr (it is not strdup'ed) */
static char **add_string_to_strings(char **strings, char *add)
{
	char *v[2];
	v[0] = add;
	v[1] = NULL;
	return add_strings_to_strings(strings, v, /*dup:*/ 0);
}
#if LEAK_HUNTING
static char **xx_add_string_to_strings(int lineno, char **strings, char *add)
{
	char **ptr = add_string_to_strings(strings, add);
	fdprintf(2, "line %d: add_string_to_strings %p\n", lineno, ptr);
	return ptr;
}
#define add_string_to_strings(strings, add) \
	xx_add_string_to_strings(__LINE__, strings, add)
#endif

static void free_strings(char **strings)
{
	char **v;

	if (!strings)
		return;
	v = strings;
	while (*v) {
		free(*v);
		v++;
	}
	free(strings);
}

static int fcntl_F_DUPFD(int fd, int avoid_fd)
{
	int newfd;
 repeat:
	newfd = fcntl(fd, F_DUPFD, avoid_fd + 1);
	if (newfd < 0) {
		if (errno == EBUSY)
			goto repeat;
		if (errno == EINTR)
			goto repeat;
	}
	return newfd;
}

static int xdup_CLOEXEC_and_close(int fd, int avoid_fd)
{
	int newfd;
 repeat:
	newfd = fcntl(fd, F_DUPFD_CLOEXEC, avoid_fd + 1);
	if (newfd < 0) {
		if (errno == EBUSY)
			goto repeat;
		if (errno == EINTR)
			goto repeat;
		/* fd was not open? */
		if (errno == EBADF)
			return fd;
		xfunc_die();
	}
	if (F_DUPFD_CLOEXEC == F_DUPFD) /* if old libc (w/o F_DUPFD_CLOEXEC) */
		fcntl(newfd, F_SETFD, FD_CLOEXEC);
	close(fd);
	return newfd;
}


/* Manipulating the list of open FILEs */
static FILE *remember_FILE(FILE *fp)
{
	if (fp) {
		struct FILE_list *n = xmalloc(sizeof(*n));
		n->next = G.FILE_list;
		G.FILE_list = n;
		n->fp = fp;
		n->fd = fileno(fp);
		close_on_exec_on(n->fd);
	}
	return fp;
}
static void fclose_and_forget(FILE *fp)
{
	struct FILE_list **pp = &G.FILE_list;
	while (*pp) {
		struct FILE_list *cur = *pp;
		if (cur->fp == fp) {
			*pp = cur->next;
			free(cur);
			break;
		}
		pp = &cur->next;
	}
	fclose(fp);
}
static int save_FILEs_on_redirect(int fd, int avoid_fd)
{
	struct FILE_list *fl = G.FILE_list;
	while (fl) {
		if (fd == fl->fd) {
			/* We use it only on script files, they are all CLOEXEC */
			fl->fd = xdup_CLOEXEC_and_close(fd, avoid_fd);
			debug_printf_redir("redirect_fd %d: matches a script fd, moving it to %d\n", fd, fl->fd);
			return 1;
		}
		fl = fl->next;
	}
	return 0;
}
static void restore_redirected_FILEs(void)
{
	struct FILE_list *fl = G.FILE_list;
	while (fl) {
		int should_be = fileno(fl->fp);
		if (fl->fd != should_be) {
			debug_printf_redir("restoring script fd from %d to %d\n", fl->fd, should_be);
			xmove_fd(fl->fd, should_be);
			fl->fd = should_be;
		}
		fl = fl->next;
	}
}
#if ENABLE_FEATURE_SH_STANDALONE && BB_MMU
static void close_all_FILE_list(void)
{
	struct FILE_list *fl = G.FILE_list;
	while (fl) {
		/* fclose would also free FILE object.
		 * It is disastrous if we share memory with a vforked parent.
		 * I'm not sure we never come here after vfork.
		 * Therefore just close fd, nothing more.
		 */
		/*fclose(fl->fp); - unsafe */
		close(fl->fd);
		fl = fl->next;
	}
}
#endif
static int fd_in_FILEs(int fd)
{
	struct FILE_list *fl = G.FILE_list;
	while (fl) {
		if (fl->fd == fd)
			return 1;
		fl = fl->next;
	}
	return 0;
}


/* Helpers for setting new $n and restoring them back
 */
typedef struct save_arg_t {
	char *sv_argv0;
	char **sv_g_argv;
	int sv_g_argc;
	IF_HUSH_SET(smallint sv_g_malloced;)
} save_arg_t;

static void save_and_replace_G_args(save_arg_t *sv, char **argv)
{
	sv->sv_argv0 = argv[0];
	sv->sv_g_argv = G.global_argv;
	sv->sv_g_argc = G.global_argc;
	IF_HUSH_SET(sv->sv_g_malloced = G.global_args_malloced;)

	argv[0] = G.global_argv[0]; /* retain $0 */
	G.global_argv = argv;
	IF_HUSH_SET(G.global_args_malloced = 0;)

	G.global_argc = 1 + string_array_len(argv + 1);
}

static void restore_G_args(save_arg_t *sv, char **argv)
{
#if ENABLE_HUSH_SET
	if (G.global_args_malloced) {
		/* someone ran "set -- arg1 arg2 ...", undo */
		char **pp = G.global_argv;
		while (*++pp) /* note: does not free $0 */
			free(*pp);
		free(G.global_argv);
	}
#endif
	argv[0] = sv->sv_argv0;
	G.global_argv = sv->sv_g_argv;
	G.global_argc = sv->sv_g_argc;
	IF_HUSH_SET(G.global_args_malloced = sv->sv_g_malloced;)
}


/* Basic theory of signal handling in shell
 * ========================================
 * This does not describe what hush does, rather, it is current understanding
 * what it _should_ do. If it doesn't, it's a bug.
 * http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#trap
 *
 * Signals are handled only after each pipe ("cmd | cmd | cmd" thing)
 * is finished or backgrounded. It is the same in interactive and
 * non-interactive shells, and is the same regardless of whether
 * a user trap handler is installed or a shell special one is in effect.
 * ^C or ^Z from keyboard seems to execute "at once" because it usually
 * backgrounds (i.e. stops) or kills all members of currently running
 * pipe.
 *
 * Wait builtin is interruptible by signals for which user trap is set
 * or by SIGINT in interactive shell.
 *
 * Trap handlers will execute even within trap handlers. (right?)
 *
 * User trap handlers are forgotten when subshell ("(cmd)") is entered,
 * except for handlers set to '' (empty string).
 *
 * If job control is off, backgrounded commands ("cmd &")
 * have SIGINT, SIGQUIT set to SIG_IGN.
 *
 * Commands which are run in command substitution ("`cmd`")
 * have SIGTTIN, SIGTTOU, SIGTSTP set to SIG_IGN.
 *
 * Ordinary commands have signals set to SIG_IGN/DFL as inherited
 * by the shell from its parent.
 *
 * Signals which differ from SIG_DFL action
 * (note: child (i.e., [v]forked) shell is not an interactive shell):
 *
 * SIGQUIT: ignore
 * SIGTERM (interactive): ignore
 * SIGHUP (interactive):
 *    send SIGCONT to stopped jobs, send SIGHUP to all jobs and exit
 * SIGTTIN, SIGTTOU, SIGTSTP (if job control is on): ignore
 *    Note that ^Z is handled not by trapping SIGTSTP, but by seeing
 *    that all pipe members are stopped. Try this in bash:
 *    while :; do :; done - ^Z does not background it
 *    (while :; do :; done) - ^Z backgrounds it
 * SIGINT (interactive): wait for last pipe, ignore the rest
 *    of the command line, show prompt. NB: ^C does not send SIGINT
 *    to interactive shell while shell is waiting for a pipe,
 *    since shell is bg'ed (is not in foreground process group).
 *    Example 1: this waits 5 sec, but does not execute ls:
 *    "echo $$; sleep 5; ls -l" + "kill -INT <pid>"
 *    Example 2: this does not wait and does not execute ls:
 *    "echo $$; sleep 5 & wait; ls -l" + "kill -INT <pid>"
 *    Example 3: this does not wait 5 sec, but executes ls:
 *    "sleep 5; ls -l" + press ^C
 *    Example 4: this does not wait and does not execute ls:
 *    "sleep 5 & wait; ls -l" + press ^C
 *
 * (What happens to signals which are IGN on shell start?)
 * (What happens with signal mask on shell start?)
 *
 * Old implementation
 * ==================
 * We use in-kernel pending signal mask to determine which signals were sent.
 * We block all signals which we don't want to take action immediately,
 * i.e. we block all signals which need to have special handling as described
 * above, and all signals which have traps set.
 * After each pipe execution, we extract any pending signals via sigtimedwait()
 * and act on them.
 *
 * unsigned special_sig_mask: a mask of such "special" signals
 * sigset_t blocked_set:  current blocked signal set
 *
 * "trap - SIGxxx":
 *    clear bit in blocked_set unless it is also in special_sig_mask
 * "trap 'cmd' SIGxxx":
 *    set bit in blocked_set (even if 'cmd' is '')
 * after [v]fork, if we plan to be a shell:
 *    unblock signals with special interactive handling
 *    (child shell is not interactive),
 *    unset all traps except '' (note: regardless of child shell's type - {}, (), etc)
 * after [v]fork, if we plan to exec:
 *    POSIX says fork clears pending signal mask in child - no need to clear it.
 *    Restore blocked signal set to one inherited by shell just prior to exec.
 *
 * Note: as a result, we do not use signal handlers much. The only uses
 * are to count SIGCHLDs
 * and to restore tty pgrp on signal-induced exit.
 *
 * Note 2 (compat):
 * Standard says "When a subshell is entered, traps that are not being ignored
 * are set to the default actions". bash interprets it so that traps which
 * are set to '' (ignore) are NOT reset to defaults. We do the same.
 *
 * Problem: the above approach makes it unwieldy to catch signals while
 * we are in read builtin, or while we read commands from stdin:
 * masked signals are not visible!
 *
 * New implementation
 * ==================
 * We record each signal we are interested in by installing signal handler
 * for them - a bit like emulating kernel pending signal mask in userspace.
 * We are interested in: signals which need to have special handling
 * as described above, and all signals which have traps set.
 * Signals are recorded in pending_set.
 * After each pipe execution, we extract any pending signals
 * and act on them.
 *
 * unsigned special_sig_mask: a mask of shell-special signals.
 * unsigned fatal_sig_mask: a mask of signals on which we restore tty pgrp.
 * char *traps[sig] if trap for sig is set (even if it's '').
 * sigset_t pending_set: set of sigs we received.
 *
 * "trap - SIGxxx":
 *    if sig is in special_sig_mask, set handler back to:
 *        record_pending_signo, or to IGN if it's a tty stop signal
 *    if sig is in fatal_sig_mask, set handler back to sigexit.
 *    else: set handler back to SIG_DFL
 * "trap 'cmd' SIGxxx":
 *    set handler to record_pending_signo.
 * "trap '' SIGxxx":
 *    set handler to SIG_IGN.
 * after [v]fork, if we plan to be a shell:
 *    set signals with special interactive handling to SIG_DFL
 *    (because child shell is not interactive),
 *    unset all traps except '' (note: regardless of child shell's type - {}, (), etc)
 * after [v]fork, if we plan to exec:
 *    POSIX says fork clears pending signal mask in child - no need to clear it.
 *
 * To make wait builtin interruptible, we handle SIGCHLD as special signal,
 * otherwise (if we leave it SIG_DFL) sigsuspend in wait builtin will not wake up on it.
 *
 * Note (compat):
 * Standard says "When a subshell is entered, traps that are not being ignored
 * are set to the default actions". bash interprets it so that traps which
 * are set to '' (ignore) are NOT reset to defaults. We do the same.
 */
enum {
	SPECIAL_INTERACTIVE_SIGS = 0
		| (1 << SIGTERM)
		| (1 << SIGINT)
		| (1 << SIGHUP)
		,
	SPECIAL_JOBSTOP_SIGS = 0
#if ENABLE_HUSH_JOB
		| (1 << SIGTTIN)
		| (1 << SIGTTOU)
		| (1 << SIGTSTP)
#endif
		,
};

static void record_pending_signo(int sig)
{
	sigaddset(&G.pending_set, sig);
#if ENABLE_HUSH_FAST
	if (sig == SIGCHLD) {
		G.count_SIGCHLD++;
//bb_error_msg("[%d] SIGCHLD_handler: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
	}
#endif
}

static sighandler_t install_sighandler(int sig, sighandler_t handler)
{
	struct sigaction old_sa;

	/* We could use signal() to install handlers... almost:
	 * except that we need to mask ALL signals while handlers run.
	 * I saw signal nesting in strace, race window isn't small.
	 * SA_RESTART is also needed, but in Linux, signal()
	 * sets SA_RESTART too.
	 */
	/* memset(&G.sa, 0, sizeof(G.sa)); - already done */
	/* sigfillset(&G.sa.sa_mask);      - already done */
	/* G.sa.sa_flags = SA_RESTART;     - already done */
	G.sa.sa_handler = handler;
	sigaction(sig, &G.sa, &old_sa);
	return old_sa.sa_handler;
}

static void hush_exit(int exitcode) NORETURN;

static void restore_ttypgrp_and__exit(void) NORETURN;
static void restore_ttypgrp_and__exit(void)
{
	/* xfunc has failed! die die die */
	/* no EXIT traps, this is an escape hatch! */
	G.exiting = 1;
	hush_exit(xfunc_error_retval);
}

#if ENABLE_HUSH_JOB

/* Needed only on some libc:
 * It was observed that on exit(), fgetc'ed buffered data
 * gets "unwound" via lseek(fd, -NUM, SEEK_CUR).
 * With the net effect that even after fork(), not vfork(),
 * exit() in NOEXECed applet in "sh SCRIPT":
 *	noexec_applet_here
 *	echo END_OF_SCRIPT
 * lseeks fd in input FILE object from EOF to "e" in "echo END_OF_SCRIPT".
 * This makes "echo END_OF_SCRIPT" executed twice.
 * Similar problems can be seen with msg_and_die_if_script() -> xfunc_die()
 * and in `cmd` handling.
 * If set as die_func(), this makes xfunc_die() exit via _exit(), not exit():
 */
static void fflush_and__exit(void) NORETURN;
static void fflush_and__exit(void)
{
	fflush_all();
	_exit(xfunc_error_retval);
}

/* After [v]fork, in child: do not restore tty pgrp on xfunc death */
# define disable_restore_tty_pgrp_on_exit() (die_func = fflush_and__exit)
/* After [v]fork, in parent: restore tty pgrp on xfunc death */
# define enable_restore_tty_pgrp_on_exit()  (die_func = restore_ttypgrp_and__exit)

/* Restores tty foreground process group, and exits.
 * May be called as signal handler for fatal signal
 * (will resend signal to itself, producing correct exit state)
 * or called directly with -EXITCODE.
 * We also call it if xfunc is exiting.
 */
static void sigexit(int sig) NORETURN;
static void sigexit(int sig)
{
	/* Careful: we can end up here after [v]fork. Do not restore
	 * tty pgrp then, only top-level shell process does that */
	if (G_saved_tty_pgrp && getpid() == G.root_pid) {
		/* Disable all signals: job control, SIGPIPE, etc.
		 * Mostly paranoid measure, to prevent infinite SIGTTOU.
		 */
		sigprocmask_allsigs(SIG_BLOCK);
		tcsetpgrp(G_interactive_fd, G_saved_tty_pgrp);
	}

	/* Not a signal, just exit */
	if (sig <= 0)
		_exit(- sig);

	kill_myself_with_sig(sig); /* does not return */
}
#else

# define disable_restore_tty_pgrp_on_exit() ((void)0)
# define enable_restore_tty_pgrp_on_exit()  ((void)0)

#endif

static sighandler_t pick_sighandler(unsigned sig)
{
	sighandler_t handler = SIG_DFL;
	if (sig < sizeof(unsigned)*8) {
		unsigned sigmask = (1 << sig);

#if ENABLE_HUSH_JOB
		/* is sig fatal? */
		if (G_fatal_sig_mask & sigmask)
			handler = sigexit;
		else
#endif
		/* sig has special handling? */
		if (G.special_sig_mask & sigmask) {
			handler = record_pending_signo;
			/* TTIN/TTOU/TSTP can't be set to record_pending_signo
			 * in order to ignore them: they will be raised
			 * in an endless loop when we try to do some
			 * terminal ioctls! We do have to _ignore_ these.
			 */
			if (SPECIAL_JOBSTOP_SIGS & sigmask)
				handler = SIG_IGN;
		}
	}
	return handler;
}

/* Restores tty foreground process group, and exits. */
static void hush_exit(int exitcode)
{
#if ENABLE_FEATURE_EDITING_SAVE_ON_EXIT
	save_history(G.line_input_state);
#endif

	fflush_all();
	if (G.exiting <= 0 && G_traps && G_traps[0] && G_traps[0][0]) {
		char *argv[3];
		/* argv[0] is unused */
		argv[1] = G_traps[0];
		argv[2] = NULL;
		G.exiting = 1; /* prevent EXIT trap recursion */
		/* Note: G_traps[0] is not cleared!
		 * "trap" will still show it, if executed
		 * in the handler */
		builtin_eval(argv);
	}

#if ENABLE_FEATURE_CLEAN_UP
	{
		struct variable *cur_var;
		if (G.cwd != bb_msg_unknown)
			free((char*)G.cwd);
		cur_var = G.top_var;
		while (cur_var) {
			struct variable *tmp = cur_var;
			if (!cur_var->max_len)
				free(cur_var->varstr);
			cur_var = cur_var->next;
			free(tmp);
		}
	}
#endif

	fflush_all();
#if ENABLE_HUSH_JOB
	sigexit(- (exitcode & 0xff));
#else
	_exit(exitcode);
#endif
}


//TODO: return a mask of ALL handled sigs?
static int check_and_run_traps(void)
{
	int last_sig = 0;

	while (1) {
		int sig;

		if (sigisemptyset(&G.pending_set))
			break;
		sig = 0;
		do {
			sig++;
			if (sigismember(&G.pending_set, sig)) {
				sigdelset(&G.pending_set, sig);
				goto got_sig;
			}
		} while (sig < NSIG);
		break;
 got_sig:
		if (G_traps && G_traps[sig]) {
			debug_printf_exec("%s: sig:%d handler:'%s'\n", __func__, sig, G.traps[sig]);
			if (G_traps[sig][0]) {
				/* We have user-defined handler */
				smalluint save_rcode;
				char *argv[3];
				/* argv[0] is unused */
				argv[1] = G_traps[sig];
				argv[2] = NULL;
				save_rcode = G.last_exitcode;
				builtin_eval(argv);
//FIXME: shouldn't it be set to 128 + sig instead?
				G.last_exitcode = save_rcode;
				last_sig = sig;
			} /* else: "" trap, ignoring signal */
			continue;
		}
		/* not a trap: special action */
		switch (sig) {
		case SIGINT:
			debug_printf_exec("%s: sig:%d default SIGINT handler\n", __func__, sig);
			G.flag_SIGINT = 1;
			last_sig = sig;
			break;
#if ENABLE_HUSH_JOB
		case SIGHUP: {
//TODO: why are we doing this? ash and dash don't do this,
//they have no handler for SIGHUP at all,
//they rely on kernel to send SIGHUP+SIGCONT to orphaned process groups
			struct pipe *job;
			debug_printf_exec("%s: sig:%d default SIGHUP handler\n", __func__, sig);
			/* bash is observed to signal whole process groups,
			 * not individual processes */
			for (job = G.job_list; job; job = job->next) {
				if (job->pgrp <= 0)
					continue;
				debug_printf_exec("HUPing pgrp %d\n", job->pgrp);
				if (kill(- job->pgrp, SIGHUP) == 0)
					kill(- job->pgrp, SIGCONT);
			}
			sigexit(SIGHUP);
		}
#endif
#if ENABLE_HUSH_FAST
		case SIGCHLD:
			debug_printf_exec("%s: sig:%d default SIGCHLD handler\n", __func__, sig);
			G.count_SIGCHLD++;
//bb_error_msg("[%d] check_and_run_traps: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
			/* Note:
			 * We don't do 'last_sig = sig' here -> NOT returning this sig.
			 * This simplifies wait builtin a bit.
			 */
			break;
#endif
		default: /* ignored: */
			debug_printf_exec("%s: sig:%d default handling is to ignore\n", __func__, sig);
			/* SIGTERM, SIGQUIT, SIGTTIN, SIGTTOU, SIGTSTP */
			/* Note:
			 * We don't do 'last_sig = sig' here -> NOT returning this sig.
			 * Example: wait is not interrupted by TERM
			 * in interactive shell, because TERM is ignored.
			 */
			break;
		}
	}
	return last_sig;
}


static const char *get_cwd(int force)
{
	if (force || G.cwd == NULL) {
		/* xrealloc_getcwd_or_warn(arg) calls free(arg),
		 * we must not try to free(bb_msg_unknown) */
		if (G.cwd == bb_msg_unknown)
			G.cwd = NULL;
		G.cwd = xrealloc_getcwd_or_warn((char *)G.cwd);
		if (!G.cwd)
			G.cwd = bb_msg_unknown;
	}
	return G.cwd;
}


/*
 * Shell and environment variable support
 */
static struct variable **get_ptr_to_local_var(const char *name, unsigned len)
{
	struct variable **pp;
	struct variable *cur;

	pp = &G.top_var;
	while ((cur = *pp) != NULL) {
		if (strncmp(cur->varstr, name, len) == 0 && cur->varstr[len] == '=')
			return pp;
		pp = &cur->next;
	}
	return NULL;
}

static const char* FAST_FUNC get_local_var_value(const char *name)
{
	struct variable **vpp;
	unsigned len = strlen(name);

	if (G.expanded_assignments) {
		char **cpp = G.expanded_assignments;
		while (*cpp) {
			char *cp = *cpp;
			if (strncmp(cp, name, len) == 0 && cp[len] == '=')
				return cp + len + 1;
			cpp++;
		}
	}

	vpp = get_ptr_to_local_var(name, len);
	if (vpp)
		return (*vpp)->varstr + len + 1;

	if (strcmp(name, "PPID") == 0)
		return utoa(G.root_ppid);
	// bash compat: UID? EUID?
#if ENABLE_HUSH_RANDOM_SUPPORT
	if (strcmp(name, "RANDOM") == 0)
		return utoa(next_random(&G.random_gen));
#endif
	return NULL;
}

/* str holds "NAME=VAL" and is expected to be malloced.
 * We take ownership of it.
 */
#define SETFLAG_EXPORT   (1 << 0)
#define SETFLAG_UNEXPORT (1 << 1)
#define SETFLAG_MAKE_RO  (1 << 2)
#define SETFLAG_LOCAL_SHIFT    3
static int set_local_var(char *str, unsigned flags)
{
	struct variable **var_pp;
	struct variable *cur;
	char *free_me = NULL;
	char *eq_sign;
	int name_len;
	IF_HUSH_LOCAL(unsigned local_lvl = (flags >> SETFLAG_LOCAL_SHIFT);)

	eq_sign = strchr(str, '=');
	if (!eq_sign) { /* not expected to ever happen? */
		free(str);
		return -1;
	}

	name_len = eq_sign - str + 1; /* including '=' */
	var_pp = &G.top_var;
	while ((cur = *var_pp) != NULL) {
		if (strncmp(cur->varstr, str, name_len) != 0) {
			var_pp = &cur->next;
			continue;
		}

		/* We found an existing var with this name */
		if (cur->flg_read_only) {
			bb_error_msg("%s: readonly variable", str);
			free(str);
//NOTE: in bash, assignment in "export READONLY_VAR=Z" fails, and sets $?=1,
//but export per se succeeds (does put the var in env). We don't mimic that.
			return -1;
		}
		if (flags & SETFLAG_UNEXPORT) { // && cur->flg_export ?
			debug_printf_env("%s: unsetenv '%s'\n", __func__, str);
			*eq_sign = '\0';
			unsetenv(str);
			*eq_sign = '=';
		}
#if ENABLE_HUSH_LOCAL
		if (cur->func_nest_level < local_lvl) {
			/* New variable is declared as local,
			 * and existing one is global, or local
			 * from enclosing function.
			 * Remove and save old one: */
			*var_pp = cur->next;
			cur->next = *G.shadowed_vars_pp;
			*G.shadowed_vars_pp = cur;
			/* bash 3.2.33(1) and exported vars:
			 * # export z=z
			 * # f() { local z=a; env | grep ^z; }
			 * # f
			 * z=a
			 * # env | grep ^z
			 * z=z
			 */
			if (cur->flg_export)
				flags |= SETFLAG_EXPORT;
			break;
		}
#endif
		if (strcmp(cur->varstr + name_len, eq_sign + 1) == 0) {
 free_and_exp:
			free(str);
			goto exp;
		}
		if (cur->max_len != 0) {
			if (cur->max_len >= strlen(str)) {
				/* This one is from startup env, reuse space */
				strcpy(cur->varstr, str);
				goto free_and_exp;
			}
			/* Can't reuse */
			cur->max_len = 0;
			goto set_str_and_exp;
		}
		/* max_len == 0 signifies "malloced" var, which we can
		 * (and have to) free. But we can't free(cur->varstr) here:
		 * if cur->flg_export is 1, it is in the environment.
		 * We should either unsetenv+free, or wait until putenv,
		 * then putenv(new)+free(old).
		 */
		free_me = cur->varstr;
		goto set_str_and_exp;
	}

	/* Not found - create new variable struct */
	cur = xzalloc(sizeof(*cur));
	IF_HUSH_LOCAL(cur->func_nest_level = local_lvl;)
	cur->next = *var_pp;
	*var_pp = cur;

 set_str_and_exp:
	cur->varstr = str;
 exp:
#if !BB_MMU || ENABLE_HUSH_READONLY
	if (flags & SETFLAG_MAKE_RO) {
		cur->flg_read_only = 1;
	}
#endif
	if (flags & SETFLAG_EXPORT)
		cur->flg_export = 1;
	if (name_len == 4 && cur->varstr[0] == 'P' && cur->varstr[1] == 'S')
		cmdedit_update_prompt();
	if (cur->flg_export) {
		if (flags & SETFLAG_UNEXPORT) {
			cur->flg_export = 0;
			/* unsetenv was already done */
		} else {
			int i;
			debug_printf_env("%s: putenv '%s'\n", __func__, cur->varstr);
			i = putenv(cur->varstr);
			/* only now we can free old exported malloced string */
			free(free_me);
			return i;
		}
	}
	free(free_me);
	return 0;
}

/* Used at startup and after each cd */
static void set_pwd_var(unsigned flag)
{
	set_local_var(xasprintf("PWD=%s", get_cwd(/*force:*/ 1)), flag);
}

static int unset_local_var_len(const char *name, int name_len)
{
	struct variable *cur;
	struct variable **var_pp;

	if (!name)
		return EXIT_SUCCESS;
	var_pp = &G.top_var;
	while ((cur = *var_pp) != NULL) {
		if (strncmp(cur->varstr, name, name_len) == 0 && cur->varstr[name_len] == '=') {
			if (cur->flg_read_only) {
				bb_error_msg("%s: readonly variable", name);
				return EXIT_FAILURE;
			}
			*var_pp = cur->next;
			debug_printf_env("%s: unsetenv '%s'\n", __func__, cur->varstr);
			bb_unsetenv(cur->varstr);
			if (name_len == 3 && cur->varstr[0] == 'P' && cur->varstr[1] == 'S')
				cmdedit_update_prompt();
			if (!cur->max_len)
				free(cur->varstr);
			free(cur);
			return EXIT_SUCCESS;
		}
		var_pp = &cur->next;
	}
	return EXIT_SUCCESS;
}

#if ENABLE_HUSH_UNSET
static int unset_local_var(const char *name)
{
	return unset_local_var_len(name, strlen(name));
}
#endif

static void unset_vars(char **strings)
{
	char **v;

	if (!strings)
		return;
	v = strings;
	while (*v) {
		const char *eq = strchrnul(*v, '=');
		unset_local_var_len(*v, (int)(eq - *v));
		v++;
	}
	free(strings);
}

#if BASH_HOSTNAME_VAR || ENABLE_FEATURE_SH_MATH || ENABLE_HUSH_READ
static void FAST_FUNC set_local_var_from_halves(const char *name, const char *val)
{
	char *var = xasprintf("%s=%s", name, val);
	set_local_var(var, /*flag:*/ 0);
}
#endif


/*
 * Helpers for "var1=val1 var2=val2 cmd" feature
 */
static void add_vars(struct variable *var)
{
	struct variable *next;

	while (var) {
		next = var->next;
		var->next = G.top_var;
		G.top_var = var;
		if (var->flg_export) {
			debug_printf_env("%s: restoring exported '%s'\n", __func__, var->varstr);
			putenv(var->varstr);
		} else {
			debug_printf_env("%s: restoring variable '%s'\n", __func__, var->varstr);
		}
		var = next;
	}
}

static struct variable *set_vars_and_save_old(char **strings)
{
	char **s;
	struct variable *old = NULL;

	if (!strings)
		return old;
	s = strings;
	while (*s) {
		struct variable *var_p;
		struct variable **var_pp;
		char *eq;

		eq = strchr(*s, '=');
		if (eq) {
			var_pp = get_ptr_to_local_var(*s, eq - *s);
			if (var_pp) {
				var_p = *var_pp;
				if (var_p->flg_read_only) {
					char **p;
					bb_error_msg("%s: readonly variable", *s);
					/*
					 * "VAR=V BLTIN" unsets VARs after BLTIN completes.
					 * If VAR is readonly, leaving it in the list
					 * after asssignment error (msg above)
					 * causes doubled error message later, on unset.
					 */
					debug_printf_env("removing/freeing '%s' element\n", *s);
					free(*s);
					p = s;
					do { *p = p[1]; p++; } while (*p);
					goto next;
				}
				/* Remove variable from global linked list */
				debug_printf_env("%s: removing '%s'\n", __func__, var_p->varstr);
				*var_pp = var_p->next;
				/* Add it to returned list */
				var_p->next = old;
				old = var_p;
			}
			set_local_var(*s, SETFLAG_EXPORT);
		}
 next:
		s++;
	}
	return old;
}


/*
 * Unicode helper
 */
static void reinit_unicode_for_hush(void)
{
	/* Unicode support should be activated even if LANG is set
	 * _during_ shell execution, not only if it was set when
	 * shell was started. Therefore, re-check LANG every time:
	 */
	if (ENABLE_FEATURE_CHECK_UNICODE_IN_ENV
	 || ENABLE_UNICODE_USING_LOCALE
        ) {
		const char *s = get_local_var_value("LC_ALL");
		if (!s) s = get_local_var_value("LC_CTYPE");
		if (!s) s = get_local_var_value("LANG");
		reinit_unicode(s);
	}
}

/*
 * in_str support (strings, and "strings" read from files).
 */

#if ENABLE_HUSH_INTERACTIVE
/* To test correct lineedit/interactive behavior, type from command line:
 *	echo $P\
 *	\
 *	AT\
 *	H\
 *	\
 * It exercises a lot of corner cases.
 */
static void cmdedit_update_prompt(void)
{
	if (ENABLE_FEATURE_EDITING_FANCY_PROMPT) {
		G.PS1 = get_local_var_value("PS1");
		if (G.PS1 == NULL)
			G.PS1 = "\\w \\$ ";
		G.PS2 = get_local_var_value("PS2");
	} else {
		G.PS1 = NULL;
	}
	if (G.PS2 == NULL)
		G.PS2 = "> ";
}
static const char *setup_prompt_string(int promptmode)
{
	const char *prompt_str;
	debug_printf("setup_prompt_string %d ", promptmode);
	if (!ENABLE_FEATURE_EDITING_FANCY_PROMPT) {
		/* Set up the prompt */
		if (promptmode == 0) { /* PS1 */
			free((char*)G.PS1);
			/* bash uses $PWD value, even if it is set by user.
			 * It uses current dir only if PWD is unset.
			 * We always use current dir. */
			G.PS1 = xasprintf("%s %c ", get_cwd(0), (geteuid() != 0) ? '$' : '#');
			prompt_str = G.PS1;
		} else
			prompt_str = G.PS2;
	} else
		prompt_str = (promptmode == 0) ? G.PS1 : G.PS2;
	debug_printf("prompt_str '%s'\n", prompt_str);
	return prompt_str;
}
static int get_user_input(struct in_str *i)
{
	int r;
	const char *prompt_str;

	prompt_str = setup_prompt_string(i->promptmode);
# if ENABLE_FEATURE_EDITING
	for (;;) {
		reinit_unicode_for_hush();
		if (G.flag_SIGINT) {
			/* There was ^C'ed, make it look prettier: */
			bb_putchar('\n');
			G.flag_SIGINT = 0;
		}
		/* buglet: SIGINT will not make new prompt to appear _at once_,
		 * only after <Enter>. (^C works immediately) */
		r = read_line_input(G.line_input_state, prompt_str,
				G.user_input_buf, CONFIG_FEATURE_EDITING_MAX_LEN-1
		);
		/* read_line_input intercepts ^C, "convert" it to SIGINT */
		if (r == 0)
			raise(SIGINT);
		check_and_run_traps();
		if (r != 0 && !G.flag_SIGINT)
			break;
		/* ^C or SIGINT: repeat */
		/* bash prints ^C even on real SIGINT (non-kbd generated) */
		write(STDOUT_FILENO, "^C", 2);
		G.last_exitcode = 128 + SIGINT;
	}
	if (r < 0) {
		/* EOF/error detected */
		i->p = NULL;
		i->peek_buf[0] = r = EOF;
		return r;
	}
	i->p = G.user_input_buf;
	return (unsigned char)*i->p++;
# else
	for (;;) {
		G.flag_SIGINT = 0;
		if (i->last_char == '\0' || i->last_char == '\n') {
			/* Why check_and_run_traps here? Try this interactively:
			 * $ trap 'echo INT' INT; (sleep 2; kill -INT $$) &
			 * $ <[enter], repeatedly...>
			 * Without check_and_run_traps, handler never runs.
			 */
			check_and_run_traps();
			fputs(prompt_str, stdout);
		}
		fflush_all();
//FIXME: here ^C or SIGINT will have effect only after <Enter>
		r = fgetc(i->file);
		/* In !ENABLE_FEATURE_EDITING we don't use read_line_input,
		 * no ^C masking happens during fgetc, no special code for ^C:
		 * it generates SIGINT as usual.
		 */
		check_and_run_traps();
		if (G.flag_SIGINT)
			G.last_exitcode = 128 + SIGINT;
		if (r != '\0')
			break;
	}
	return r;
# endif
}
/* This is the magic location that prints prompts
 * and gets data back from the user */
static int fgetc_interactive(struct in_str *i)
{
	int ch;
	/* If it's interactive stdin, get new line. */
	if (G_interactive_fd && i->file == stdin) {
		/* Returns first char (or EOF), the rest is in i->p[] */
		ch = get_user_input(i);
		i->promptmode = 1; /* PS2 */
	} else {
		/* Not stdin: script file, sourced file, etc */
		do ch = fgetc(i->file); while (ch == '\0');
	}
	return ch;
}
#else
static inline int fgetc_interactive(struct in_str *i)
{
	int ch;
	do ch = fgetc(i->file); while (ch == '\0');
	return ch;
}
#endif  /* INTERACTIVE */

static int i_getch(struct in_str *i)
{
	int ch;

	if (!i->file) {
		/* string-based in_str */
		ch = (unsigned char)*i->p;
		if (ch != '\0') {
			i->p++;
			i->last_char = ch;
			return ch;
		}
		return EOF;
	}

	/* FILE-based in_str */

#if ENABLE_FEATURE_EDITING
	/* This can be stdin, check line editing char[] buffer */
	if (i->p && *i->p != '\0') {
		ch = (unsigned char)*i->p++;
		goto out;
	}
#endif
	/* peek_buf[] is an int array, not char. Can contain EOF. */
	ch = i->peek_buf[0];
	if (ch != 0) {
		int ch2 = i->peek_buf[1];
		i->peek_buf[0] = ch2;
		if (ch2 == 0) /* very likely, avoid redundant write */
			goto out;
		i->peek_buf[1] = 0;
		goto out;
	}

	ch = fgetc_interactive(i);
 out:
	debug_printf("file_get: got '%c' %d\n", ch, ch);
	i->last_char = ch;
	return ch;
}

static int i_peek(struct in_str *i)
{
	int ch;

	if (!i->file) {
		/* string-based in_str */
		/* Doesn't report EOF on NUL. None of the callers care. */
		return (unsigned char)*i->p;
	}

	/* FILE-based in_str */

#if ENABLE_FEATURE_EDITING && ENABLE_HUSH_INTERACTIVE
	/* This can be stdin, check line editing char[] buffer */
	if (i->p && *i->p != '\0')
		return (unsigned char)*i->p;
#endif
	/* peek_buf[] is an int array, not char. Can contain EOF. */
	ch = i->peek_buf[0];
	if (ch != 0)
		return ch;

	/* Need to get a new char */
	ch = fgetc_interactive(i);
	debug_printf("file_peek: got '%c' %d\n", ch, ch);

	/* Save it by either rolling back line editing buffer, or in i->peek_buf[0] */
#if ENABLE_FEATURE_EDITING && ENABLE_HUSH_INTERACTIVE
	if (i->p) {
		i->p -= 1;
		return ch;
	}
#endif
	i->peek_buf[0] = ch;
	/*i->peek_buf[1] = 0; - already is */
	return ch;
}

/* Only ever called if i_peek() was called, and did not return EOF.
 * IOW: we know the previous peek saw an ordinary char, not EOF, not NUL,
 * not end-of-line. Therefore we never need to read a new editing line here.
 */
static int i_peek2(struct in_str *i)
{
	int ch;

	/* There are two cases when i->p[] buffer exists.
	 * (1) it's a string in_str.
	 * (2) It's a file, and we have a saved line editing buffer.
	 * In both cases, we know that i->p[0] exists and not NUL, and
	 * the peek2 result is in i->p[1].
	 */
	if (i->p)
		return (unsigned char)i->p[1];

	/* Now we know it is a file-based in_str. */

	/* peek_buf[] is an int array, not char. Can contain EOF. */
	/* Is there 2nd char? */
	ch = i->peek_buf[1];
	if (ch == 0) {
		/* We did not read it yet, get it now */
		do ch = fgetc(i->file); while (ch == '\0');
		i->peek_buf[1] = ch;
	}

	debug_printf("file_peek2: got '%c' %d\n", ch, ch);
	return ch;
}

static void setup_file_in_str(struct in_str *i, FILE *f)
{
	memset(i, 0, sizeof(*i));
	/* i->promptmode = 0; - PS1 (memset did it) */
	i->file = f;
	/* i->p = NULL; */
}

static void setup_string_in_str(struct in_str *i, const char *s)
{
	memset(i, 0, sizeof(*i));
	/* i->promptmode = 0; - PS1 (memset did it) */
	/*i->file = NULL */;
	i->p = s;
}


/*
 * o_string support
 */
#define B_CHUNK  (32 * sizeof(char*))

static void o_reset_to_empty_unquoted(o_string *o)
{
	o->length = 0;
	o->has_quoted_part = 0;
	if (o->data)
		o->data[0] = '\0';
}

static void o_free(o_string *o)
{
	free(o->data);
	memset(o, 0, sizeof(*o));
}

static ALWAYS_INLINE void o_free_unsafe(o_string *o)
{
	free(o->data);
}

static void o_grow_by(o_string *o, int len)
{
	if (o->length + len > o->maxlen) {
		o->maxlen += (2 * len) | (B_CHUNK-1);
		o->data = xrealloc(o->data, 1 + o->maxlen);
	}
}

static void o_addchr(o_string *o, int ch)
{
	debug_printf("o_addchr: '%c' o->length=%d o=%p\n", ch, o->length, o);
	if (o->length < o->maxlen) {
		/* likely. avoid o_grow_by() call */
 add:
		o->data[o->length] = ch;
		o->length++;
		o->data[o->length] = '\0';
		return;
	}
	o_grow_by(o, 1);
	goto add;
}

#if 0
/* Valid only if we know o_string is not empty */
static void o_delchr(o_string *o)
{
	o->length--;
	o->data[o->length] = '\0';
}
#endif

static void o_addblock(o_string *o, const char *str, int len)
{
	o_grow_by(o, len);
	((char*)mempcpy(&o->data[o->length], str, len))[0] = '\0';
	o->length += len;
}

static void o_addstr(o_string *o, const char *str)
{
	o_addblock(o, str, strlen(str));
}

#if !BB_MMU
static void nommu_addchr(o_string *o, int ch)
{
	if (o)
		o_addchr(o, ch);
}
#else
# define nommu_addchr(o, str) ((void)0)
#endif

static void o_addstr_with_NUL(o_string *o, const char *str)
{
	o_addblock(o, str, strlen(str) + 1);
}

/*
 * HUSH_BRACE_EXPANSION code needs corresponding quoting on variable expansion side.
 * Currently, "v='{q,w}'; echo $v" erroneously expands braces in $v.
 * Apparently, on unquoted $v bash still does globbing
 * ("v='*.txt'; echo $v" prints all .txt files),
 * but NOT brace expansion! Thus, there should be TWO independent
 * quoting mechanisms on $v expansion side: one protects
 * $v from brace expansion, and other additionally protects "$v" against globbing.
 * We have only second one.
 */

#if ENABLE_HUSH_BRACE_EXPANSION
# define MAYBE_BRACES "{}"
#else
# define MAYBE_BRACES ""
#endif

/* My analysis of quoting semantics tells me that state information
 * is associated with a destination, not a source.
 */
static void o_addqchr(o_string *o, int ch)
{
	int sz = 1;
	char *found = strchr("*?[\\" MAYBE_BRACES, ch);
	if (found)
		sz++;
	o_grow_by(o, sz);
	if (found) {
		o->data[o->length] = '\\';
		o->length++;
	}
	o->data[o->length] = ch;
	o->length++;
	o->data[o->length] = '\0';
}

static void o_addQchr(o_string *o, int ch)
{
	int sz = 1;
	if ((o->o_expflags & EXP_FLAG_ESC_GLOB_CHARS)
	 && strchr("*?[\\" MAYBE_BRACES, ch)
	) {
		sz++;
		o->data[o->length] = '\\';
		o->length++;
	}
	o_grow_by(o, sz);
	o->data[o->length] = ch;
	o->length++;
	o->data[o->length] = '\0';
}

static void o_addqblock(o_string *o, const char *str, int len)
{
	while (len) {
		char ch;
		int sz;
		int ordinary_cnt = strcspn(str, "*?[\\" MAYBE_BRACES);
		if (ordinary_cnt > len) /* paranoia */
			ordinary_cnt = len;
		o_addblock(o, str, ordinary_cnt);
		if (ordinary_cnt == len)
			return; /* NUL is already added by o_addblock */
		str += ordinary_cnt;
		len -= ordinary_cnt + 1; /* we are processing + 1 char below */

		ch = *str++;
		sz = 1;
		if (ch) { /* it is necessarily one of "*?[\\" MAYBE_BRACES */
			sz++;
			o->data[o->length] = '\\';
			o->length++;
		}
		o_grow_by(o, sz);
		o->data[o->length] = ch;
		o->length++;
	}
	o->data[o->length] = '\0';
}

static void o_addQblock(o_string *o, const char *str, int len)
{
	if (!(o->o_expflags & EXP_FLAG_ESC_GLOB_CHARS)) {
		o_addblock(o, str, len);
		return;
	}
	o_addqblock(o, str, len);
}

static void o_addQstr(o_string *o, const char *str)
{
	o_addQblock(o, str, strlen(str));
}

/* A special kind of o_string for $VAR and `cmd` expansion.
 * It contains char* list[] at the beginning, which is grown in 16 element
 * increments. Actual string data starts at the next multiple of 16 * (char*).
 * list[i] contains an INDEX (int!) into this string data.
 * It means that if list[] needs to grow, data needs to be moved higher up
 * but list[i]'s need not be modified.
 * NB: remembering how many list[i]'s you have there is crucial.
 * o_finalize_list() operation post-processes this structure - calculates
 * and stores actual char* ptrs in list[]. Oh, it NULL terminates it as well.
 */
#if DEBUG_EXPAND || DEBUG_GLOB
static void debug_print_list(const char *prefix, o_string *o, int n)
{
	char **list = (char**)o->data;
	int string_start = ((n + 0xf) & ~0xf) * sizeof(list[0]);
	int i = 0;

	indent();
	fdprintf(2, "%s: list:%p n:%d string_start:%d length:%d maxlen:%d glob:%d quoted:%d escape:%d\n",
			prefix, list, n, string_start, o->length, o->maxlen,
			!!(o->o_expflags & EXP_FLAG_GLOB),
			o->has_quoted_part,
			!!(o->o_expflags & EXP_FLAG_ESC_GLOB_CHARS));
	while (i < n) {
		indent();
		fdprintf(2, " list[%d]=%d '%s' %p\n", i, (int)(uintptr_t)list[i],
				o->data + (int)(uintptr_t)list[i] + string_start,
				o->data + (int)(uintptr_t)list[i] + string_start);
		i++;
	}
	if (n) {
		const char *p = o->data + (int)(uintptr_t)list[n - 1] + string_start;
		indent();
		fdprintf(2, " total_sz:%ld\n", (long)((p + strlen(p) + 1) - o->data));
	}
}
#else
# define debug_print_list(prefix, o, n) ((void)0)
#endif

/* n = o_save_ptr_helper(str, n) "starts new string" by storing an index value
 * in list[n] so that it points past last stored byte so far.
 * It returns n+1. */
static int o_save_ptr_helper(o_string *o, int n)
{
	char **list = (char**)o->data;
	int string_start;
	int string_len;

	if (!o->has_empty_slot) {
		string_start = ((n + 0xf) & ~0xf) * sizeof(list[0]);
		string_len = o->length - string_start;
		if (!(n & 0xf)) { /* 0, 0x10, 0x20...? */
			debug_printf_list("list[%d]=%d string_start=%d (growing)\n", n, string_len, string_start);
			/* list[n] points to string_start, make space for 16 more pointers */
			o->maxlen += 0x10 * sizeof(list[0]);
			o->data = xrealloc(o->data, o->maxlen + 1);
			list = (char**)o->data;
			memmove(list + n + 0x10, list + n, string_len);
			o->length += 0x10 * sizeof(list[0]);
		} else {
			debug_printf_list("list[%d]=%d string_start=%d\n",
					n, string_len, string_start);
		}
	} else {
		/* We have empty slot at list[n], reuse without growth */
		string_start = ((n+1 + 0xf) & ~0xf) * sizeof(list[0]); /* NB: n+1! */
		string_len = o->length - string_start;
		debug_printf_list("list[%d]=%d string_start=%d (empty slot)\n",
				n, string_len, string_start);
		o->has_empty_slot = 0;
	}
	o->has_quoted_part = 0;
	list[n] = (char*)(uintptr_t)string_len;
	return n + 1;
}

/* "What was our last o_save_ptr'ed position (byte offset relative o->data)?" */
static int o_get_last_ptr(o_string *o, int n)
{
	char **list = (char**)o->data;
	int string_start = ((n + 0xf) & ~0xf) * sizeof(list[0]);

	return ((int)(uintptr_t)list[n-1]) + string_start;
}

#if ENABLE_HUSH_BRACE_EXPANSION
/* There in a GNU extension, GLOB_BRACE, but it is not usable:
 * first, it processes even {a} (no commas), second,
 * I didn't manage to make it return strings when they don't match
 * existing files. Need to re-implement it.
 */

/* Helper */
static int glob_needed(const char *s)
{
	while (*s) {
		if (*s == '\\') {
			if (!s[1])
				return 0;
			s += 2;
			continue;
		}
		if (*s == '*' || *s == '[' || *s == '?' || *s == '{')
			return 1;
		s++;
	}
	return 0;
}
/* Return pointer to next closing brace or to comma */
static const char *next_brace_sub(const char *cp)
{
	unsigned depth = 0;
	cp++;
	while (*cp != '\0') {
		if (*cp == '\\') {
			if (*++cp == '\0')
				break;
			cp++;
			continue;
		}
		if ((*cp == '}' && depth-- == 0) || (*cp == ',' && depth == 0))
			break;
		if (*cp++ == '{')
			depth++;
	}

	return *cp != '\0' ? cp : NULL;
}
/* Recursive brace globber. Note: may garble pattern[]. */
static int glob_brace(char *pattern, o_string *o, int n)
{
	char *new_pattern_buf;
	const char *begin;
	const char *next;
	const char *rest;
	const char *p;
	size_t rest_len;

	debug_printf_glob("glob_brace('%s')\n", pattern);

	begin = pattern;
	while (1) {
		if (*begin == '\0')
			goto simple_glob;
		if (*begin == '{') {
			/* Find the first sub-pattern and at the same time
			 * find the rest after the closing brace */
			next = next_brace_sub(begin);
			if (next == NULL) {
				/* An illegal expression */
				goto simple_glob;
			}
			if (*next == '}') {
				/* "{abc}" with no commas - illegal
				 * brace expr, disregard and skip it */
				begin = next + 1;
				continue;
			}
			break;
		}
		if (*begin == '\\' && begin[1] != '\0')
			begin++;
		begin++;
	}
	debug_printf_glob("begin:%s\n", begin);
	debug_printf_glob("next:%s\n", next);

	/* Now find the end of the whole brace expression */
	rest = next;
	while (*rest != '}') {
		rest = next_brace_sub(rest);
		if (rest == NULL) {
			/* An illegal expression */
			goto simple_glob;
		}
		debug_printf_glob("rest:%s\n", rest);
	}
	rest_len = strlen(++rest) + 1;

	/* We are sure the brace expression is well-formed */

	/* Allocate working buffer large enough for our work */
	new_pattern_buf = xmalloc(strlen(pattern));

	/* We have a brace expression.  BEGIN points to the opening {,
	 * NEXT points past the terminator of the first element, and REST
	 * points past the final }.  We will accumulate result names from
	 * recursive runs for each brace alternative in the buffer using
	 * GLOB_APPEND.  */

	p = begin + 1;
	while (1) {
		/* Construct the new glob expression */
		memcpy(
			mempcpy(
				mempcpy(new_pattern_buf,
					/* We know the prefix for all sub-patterns */
					pattern, begin - pattern),
				p, next - p),
			rest, rest_len);

		/* Note: glob_brace() may garble new_pattern_buf[].
		 * That's why we re-copy prefix every time (1st memcpy above).
		 */
		n = glob_brace(new_pattern_buf, o, n);
		if (*next == '}') {
			/* We saw the last entry */
			break;
		}
		p = next + 1;
		next = next_brace_sub(next);
	}
	free(new_pattern_buf);
	return n;

 simple_glob:
	{
		int gr;
		glob_t globdata;

		memset(&globdata, 0, sizeof(globdata));
		gr = glob(pattern, 0, NULL, &globdata);
		debug_printf_glob("glob('%s'):%d\n", pattern, gr);
		if (gr != 0) {
			if (gr == GLOB_NOMATCH) {
				globfree(&globdata);
				/* NB: garbles parameter */
				unbackslash(pattern);
				o_addstr_with_NUL(o, pattern);
				debug_printf_glob("glob pattern '%s' is literal\n", pattern);
				return o_save_ptr_helper(o, n);
			}
			if (gr == GLOB_NOSPACE)
				bb_error_msg_and_die(bb_msg_memory_exhausted);
			/* GLOB_ABORTED? Only happens with GLOB_ERR flag,
			 * but we didn't specify it. Paranoia again. */
			bb_error_msg_and_die("glob error %d on '%s'", gr, pattern);
		}
		if (globdata.gl_pathv && globdata.gl_pathv[0]) {
			char **argv = globdata.gl_pathv;
			while (1) {
				o_addstr_with_NUL(o, *argv);
				n = o_save_ptr_helper(o, n);
				argv++;
				if (!*argv)
					break;
			}
		}
		globfree(&globdata);
	}
	return n;
}
/* Performs globbing on last list[],
 * saving each result as a new list[].
 */
static int perform_glob(o_string *o, int n)
{
	char *pattern, *copy;

	debug_printf_glob("start perform_glob: n:%d o->data:%p\n", n, o->data);
	if (!o->data)
		return o_save_ptr_helper(o, n);
	pattern = o->data + o_get_last_ptr(o, n);
	debug_printf_glob("glob pattern '%s'\n", pattern);
	if (!glob_needed(pattern)) {
		/* unbackslash last string in o in place, fix length */
		o->length = unbackslash(pattern) - o->data;
		debug_printf_glob("glob pattern '%s' is literal\n", pattern);
		return o_save_ptr_helper(o, n);
	}

	copy = xstrdup(pattern);
	/* "forget" pattern in o */
	o->length = pattern - o->data;
	n = glob_brace(copy, o, n);
	free(copy);
	if (DEBUG_GLOB)
		debug_print_list("perform_glob returning", o, n);
	return n;
}

#else /* !HUSH_BRACE_EXPANSION */

/* Helper */
static int glob_needed(const char *s)
{
	while (*s) {
		if (*s == '\\') {
			if (!s[1])
				return 0;
			s += 2;
			continue;
		}
		if (*s == '*' || *s == '[' || *s == '?')
			return 1;
		s++;
	}
	return 0;
}
/* Performs globbing on last list[],
 * saving each result as a new list[].
 */
static int perform_glob(o_string *o, int n)
{
	glob_t globdata;
	int gr;
	char *pattern;

	debug_printf_glob("start perform_glob: n:%d o->data:%p\n", n, o->data);
	if (!o->data)
		return o_save_ptr_helper(o, n);
	pattern = o->data + o_get_last_ptr(o, n);
	debug_printf_glob("glob pattern '%s'\n", pattern);
	if (!glob_needed(pattern)) {
 literal:
		/* unbackslash last string in o in place, fix length */
		o->length = unbackslash(pattern) - o->data;
		debug_printf_glob("glob pattern '%s' is literal\n", pattern);
		return o_save_ptr_helper(o, n);
	}

	memset(&globdata, 0, sizeof(globdata));
	/* Can't use GLOB_NOCHECK: it does not unescape the string.
	 * If we glob "*.\*" and don't find anything, we need
	 * to fall back to using literal "*.*", but GLOB_NOCHECK
	 * will return "*.\*"!
	 */
	gr = glob(pattern, 0, NULL, &globdata);
	debug_printf_glob("glob('%s'):%d\n", pattern, gr);
	if (gr != 0) {
		if (gr == GLOB_NOMATCH) {
			globfree(&globdata);
			goto literal;
		}
		if (gr == GLOB_NOSPACE)
			bb_error_msg_and_die(bb_msg_memory_exhausted);
		/* GLOB_ABORTED? Only happens with GLOB_ERR flag,
		 * but we didn't specify it. Paranoia again. */
		bb_error_msg_and_die("glob error %d on '%s'", gr, pattern);
	}
	if (globdata.gl_pathv && globdata.gl_pathv[0]) {
		char **argv = globdata.gl_pathv;
		/* "forget" pattern in o */
		o->length = pattern - o->data;
		while (1) {
			o_addstr_with_NUL(o, *argv);
			n = o_save_ptr_helper(o, n);
			argv++;
			if (!*argv)
				break;
		}
	}
	globfree(&globdata);
	if (DEBUG_GLOB)
		debug_print_list("perform_glob returning", o, n);
	return n;
}

#endif /* !HUSH_BRACE_EXPANSION */

/* If o->o_expflags & EXP_FLAG_GLOB, glob the string so far remembered.
 * Otherwise, just finish current list[] and start new */
static int o_save_ptr(o_string *o, int n)
{
	if (o->o_expflags & EXP_FLAG_GLOB) {
		/* If o->has_empty_slot, list[n] was already globbed
		 * (if it was requested back then when it was filled)
		 * so don't do that again! */
		if (!o->has_empty_slot)
			return perform_glob(o, n); /* o_save_ptr_helper is inside */
	}
	return o_save_ptr_helper(o, n);
}

/* "Please convert list[n] to real char* ptrs, and NULL terminate it." */
static char **o_finalize_list(o_string *o, int n)
{
	char **list;
	int string_start;

	n = o_save_ptr(o, n); /* force growth for list[n] if necessary */
	if (DEBUG_EXPAND)
		debug_print_list("finalized", o, n);
	debug_printf_expand("finalized n:%d\n", n);
	list = (char**)o->data;
	string_start = ((n + 0xf) & ~0xf) * sizeof(list[0]);
	list[--n] = NULL;
	while (n) {
		n--;
		list[n] = o->data + (int)(uintptr_t)list[n] + string_start;
	}
	return list;
}

static void free_pipe_list(struct pipe *pi);

/* Returns pi->next - next pipe in the list */
static struct pipe *free_pipe(struct pipe *pi)
{
	struct pipe *next;
	int i;

	debug_printf_clean("free_pipe (pid %d)\n", getpid());
	for (i = 0; i < pi->num_cmds; i++) {
		struct command *command;
		struct redir_struct *r, *rnext;

		command = &pi->cmds[i];
		debug_printf_clean("  command %d:\n", i);
		if (command->argv) {
			if (DEBUG_CLEAN) {
				int a;
				char **p;
				for (a = 0, p = command->argv; *p; a++, p++) {
					debug_printf_clean("   argv[%d] = %s\n", a, *p);
				}
			}
			free_strings(command->argv);
			//command->argv = NULL;
		}
		/* not "else if": on syntax error, we may have both! */
		if (command->group) {
			debug_printf_clean("   begin group (cmd_type:%d)\n",
					command->cmd_type);
			free_pipe_list(command->group);
			debug_printf_clean("   end group\n");
			//command->group = NULL;
		}
		/* else is crucial here.
		 * If group != NULL, child_func is meaningless */
#if ENABLE_HUSH_FUNCTIONS
		else if (command->child_func) {
			debug_printf_exec("cmd %p releases child func at %p\n", command, command->child_func);
			command->child_func->parent_cmd = NULL;
		}
#endif
#if !BB_MMU
		free(command->group_as_string);
		//command->group_as_string = NULL;
#endif
		for (r = command->redirects; r; r = rnext) {
			debug_printf_clean("   redirect %d%s",
					r->rd_fd, redir_table[r->rd_type].descrip);
			/* guard against the case >$FOO, where foo is unset or blank */
			if (r->rd_filename) {
				debug_printf_clean(" fname:'%s'\n", r->rd_filename);
				free(r->rd_filename);
				//r->rd_filename = NULL;
			}
			debug_printf_clean(" rd_dup:%d\n", r->rd_dup);
			rnext = r->next;
			free(r);
		}
		//command->redirects = NULL;
	}
	free(pi->cmds);   /* children are an array, they get freed all at once */
	//pi->cmds = NULL;
#if ENABLE_HUSH_JOB
	free(pi->cmdtext);
	//pi->cmdtext = NULL;
#endif

	next = pi->next;
	free(pi);
	return next;
}

static void free_pipe_list(struct pipe *pi)
{
	while (pi) {
#if HAS_KEYWORDS
		debug_printf_clean("pipe reserved word %d\n", pi->res_word);
#endif
		debug_printf_clean("pipe followup code %d\n", pi->followup);
		pi = free_pipe(pi);
	}
}


/*** Parsing routines ***/

#ifndef debug_print_tree
static void debug_print_tree(struct pipe *pi, int lvl)
{
	static const char *const PIPE[] = {
		[PIPE_SEQ] = "SEQ",
		[PIPE_AND] = "AND",
		[PIPE_OR ] = "OR" ,
		[PIPE_BG ] = "BG" ,
	};
	static const char *RES[] = {
		[RES_NONE ] = "NONE" ,
# if ENABLE_HUSH_IF
		[RES_IF   ] = "IF"   ,
		[RES_THEN ] = "THEN" ,
		[RES_ELIF ] = "ELIF" ,
		[RES_ELSE ] = "ELSE" ,
		[RES_FI   ] = "FI"   ,
# endif
# if ENABLE_HUSH_LOOPS
		[RES_FOR  ] = "FOR"  ,
		[RES_WHILE] = "WHILE",
		[RES_UNTIL] = "UNTIL",
		[RES_DO   ] = "DO"   ,
		[RES_DONE ] = "DONE" ,
# endif
# if ENABLE_HUSH_LOOPS || ENABLE_HUSH_CASE
		[RES_IN   ] = "IN"   ,
# endif
# if ENABLE_HUSH_CASE
		[RES_CASE ] = "CASE" ,
		[RES_CASE_IN ] = "CASE_IN" ,
		[RES_MATCH] = "MATCH",
		[RES_CASE_BODY] = "CASE_BODY",
		[RES_ESAC ] = "ESAC" ,
# endif
		[RES_XXXX ] = "XXXX" ,
		[RES_SNTX ] = "SNTX" ,
	};
	static const char *const CMDTYPE[] = {
		"{}",
		"()",
		"[noglob]",
# if ENABLE_HUSH_FUNCTIONS
		"func()",
# endif
	};

	int pin, prn;

	pin = 0;
	while (pi) {
		fdprintf(2, "%*spipe %d res_word=%s followup=%d %s\n", lvl*2, "",
				pin, RES[pi->res_word], pi->followup, PIPE[pi->followup]);
		prn = 0;
		while (prn < pi->num_cmds) {
			struct command *command = &pi->cmds[prn];
			char **argv = command->argv;

			fdprintf(2, "%*s cmd %d assignment_cnt:%d",
					lvl*2, "", prn,
					command->assignment_cnt);
			if (command->group) {
				fdprintf(2, " group %s: (argv=%p)%s%s\n",
						CMDTYPE[command->cmd_type],
						argv
# if !BB_MMU
						, " group_as_string:", command->group_as_string
# else
						, "", ""
# endif
				);
				debug_print_tree(command->group, lvl+1);
				prn++;
				continue;
			}
			if (argv) while (*argv) {
				fdprintf(2, " '%s'", *argv);
				argv++;
			}
			fdprintf(2, "\n");
			prn++;
		}
		pi = pi->next;
		pin++;
	}
}
#endif /* debug_print_tree */

static struct pipe *new_pipe(void)
{
	struct pipe *pi;
	pi = xzalloc(sizeof(struct pipe));
	/*pi->res_word = RES_NONE; - RES_NONE is 0 anyway */
	return pi;
}

/* Command (member of a pipe) is complete, or we start a new pipe
 * if ctx->command is NULL.
 * No errors possible here.
 */
static int done_command(struct parse_context *ctx)
{
	/* The command is really already in the pipe structure, so
	 * advance the pipe counter and make a new, null command. */
	struct pipe *pi = ctx->pipe;
	struct command *command = ctx->command;

#if 0	/* Instead we emit error message at run time */
	if (ctx->pending_redirect) {
		/* For example, "cmd >" (no filename to redirect to) */
		syntax_error("invalid redirect");
		ctx->pending_redirect = NULL;
	}
#endif

	if (command) {
		if (IS_NULL_CMD(command)) {
			debug_printf_parse("done_command: skipping null cmd, num_cmds=%d\n", pi->num_cmds);
			goto clear_and_ret;
		}
		pi->num_cmds++;
		debug_printf_parse("done_command: ++num_cmds=%d\n", pi->num_cmds);
		//debug_print_tree(ctx->list_head, 20);
	} else {
		debug_printf_parse("done_command: initializing, num_cmds=%d\n", pi->num_cmds);
	}

	/* Only real trickiness here is that the uncommitted
	 * command structure is not counted in pi->num_cmds. */
	pi->cmds = xrealloc(pi->cmds, sizeof(*pi->cmds) * (pi->num_cmds+1));
	ctx->command = command = &pi->cmds[pi->num_cmds];
 clear_and_ret:
	memset(command, 0, sizeof(*command));
	return pi->num_cmds; /* used only for 0/nonzero check */
}

static void done_pipe(struct parse_context *ctx, pipe_style type)
{
	int not_null;

	debug_printf_parse("done_pipe entered, followup %d\n", type);
	/* Close previous command */
	not_null = done_command(ctx);
#if HAS_KEYWORDS
	ctx->pipe->pi_inverted = ctx->ctx_inverted;
	ctx->ctx_inverted = 0;
	ctx->pipe->res_word = ctx->ctx_res_w;
#endif
	if (type == PIPE_BG && ctx->list_head != ctx->pipe) {
		/* Necessary since && and || have precedence over &:
		 * "cmd1 && cmd2 &" must spawn both cmds, not only cmd2,
		 * in a backgrounded subshell.
		 */
		struct pipe *pi;
		struct command *command;

		/* Is this actually this construct, all pipes end with && or ||? */
		pi = ctx->list_head;
		while (pi != ctx->pipe) {
			if (pi->followup != PIPE_AND && pi->followup != PIPE_OR)
				goto no_conv;
			pi = pi->next;
		}

		debug_printf_parse("BG with more than one pipe, converting to { p1 &&...pN; } &\n");
		pi->followup = PIPE_SEQ; /* close pN _not_ with "&"! */
		pi = xzalloc(sizeof(*pi));
		pi->followup = PIPE_BG;
		pi->num_cmds = 1;
		pi->cmds = xzalloc(sizeof(pi->cmds[0]));
		command = &pi->cmds[0];
		if (CMD_NORMAL != 0) /* "if xzalloc didn't do that already" */
			command->cmd_type = CMD_NORMAL;
		command->group = ctx->list_head;
#if !BB_MMU
		command->group_as_string = xstrndup(
			    ctx->as_string.data,
			    ctx->as_string.length - 1 /* do not copy last char, "&" */
		);
#endif
		/* Replace all pipes in ctx with one newly created */
		ctx->list_head = ctx->pipe = pi;
	} else {
 no_conv:
		ctx->pipe->followup = type;
	}

	/* Without this check, even just <enter> on command line generates
	 * tree of three NOPs (!). Which is harmless but annoying.
	 * IOW: it is safe to do it unconditionally. */
	if (not_null
#if ENABLE_HUSH_IF
	 || ctx->ctx_res_w == RES_FI
#endif
#if ENABLE_HUSH_LOOPS
	 || ctx->ctx_res_w == RES_DONE
	 || ctx->ctx_res_w == RES_FOR
	 || ctx->ctx_res_w == RES_IN
#endif
#if ENABLE_HUSH_CASE
	 || ctx->ctx_res_w == RES_ESAC
#endif
	) {
		struct pipe *new_p;
		debug_printf_parse("done_pipe: adding new pipe: "
				"not_null:%d ctx->ctx_res_w:%d\n",
				not_null, ctx->ctx_res_w);
		new_p = new_pipe();
		ctx->pipe->next = new_p;
		ctx->pipe = new_p;
		/* RES_THEN, RES_DO etc are "sticky" -
		 * they remain set for pipes inside if/while.
		 * This is used to control execution.
		 * RES_FOR and RES_IN are NOT sticky (needed to support
		 * cases where variable or value happens to match a keyword):
		 */
#if ENABLE_HUSH_LOOPS
		if (ctx->ctx_res_w == RES_FOR
		 || ctx->ctx_res_w == RES_IN)
			ctx->ctx_res_w = RES_NONE;
#endif
#if ENABLE_HUSH_CASE
		if (ctx->ctx_res_w == RES_MATCH)
			ctx->ctx_res_w = RES_CASE_BODY;
		if (ctx->ctx_res_w == RES_CASE)
			ctx->ctx_res_w = RES_CASE_IN;
#endif
		ctx->command = NULL; /* trick done_command below */
		/* Create the memory for command, roughly:
		 * ctx->pipe->cmds = new struct command;
		 * ctx->command = &ctx->pipe->cmds[0];
		 */
		done_command(ctx);
		//debug_print_tree(ctx->list_head, 10);
	}
	debug_printf_parse("done_pipe return\n");
}

static void initialize_context(struct parse_context *ctx)
{
	memset(ctx, 0, sizeof(*ctx));
	ctx->pipe = ctx->list_head = new_pipe();
	/* Create the memory for command, roughly:
	 * ctx->pipe->cmds = new struct command;
	 * ctx->command = &ctx->pipe->cmds[0];
	 */
	done_command(ctx);
}

/* If a reserved word is found and processed, parse context is modified
 * and 1 is returned.
 */
#if HAS_KEYWORDS
struct reserved_combo {
	char literal[6];
	unsigned char res;
	unsigned char assignment_flag;
	int flag;
};
enum {
	FLAG_END   = (1 << RES_NONE ),
# if ENABLE_HUSH_IF
	FLAG_IF    = (1 << RES_IF   ),
	FLAG_THEN  = (1 << RES_THEN ),
	FLAG_ELIF  = (1 << RES_ELIF ),
	FLAG_ELSE  = (1 << RES_ELSE ),
	FLAG_FI    = (1 << RES_FI   ),
# endif
# if ENABLE_HUSH_LOOPS
	FLAG_FOR   = (1 << RES_FOR  ),
	FLAG_WHILE = (1 << RES_WHILE),
	FLAG_UNTIL = (1 << RES_UNTIL),
	FLAG_DO    = (1 << RES_DO   ),
	FLAG_DONE  = (1 << RES_DONE ),
	FLAG_IN    = (1 << RES_IN   ),
# endif
# if ENABLE_HUSH_CASE
	FLAG_MATCH = (1 << RES_MATCH),
	FLAG_ESAC  = (1 << RES_ESAC ),
# endif
	FLAG_START = (1 << RES_XXXX ),
};

static const struct reserved_combo* match_reserved_word(o_string *word)
{
	/* Mostly a list of accepted follow-up reserved words.
	 * FLAG_END means we are done with the sequence, and are ready
	 * to turn the compound list into a command.
	 * FLAG_START means the word must start a new compound list.
	 */
	static const struct reserved_combo reserved_list[] = {
# if ENABLE_HUSH_IF
		{ "!",     RES_NONE,  NOT_ASSIGNMENT  , 0 },
		{ "if",    RES_IF,    MAYBE_ASSIGNMENT, FLAG_THEN | FLAG_START },
		{ "then",  RES_THEN,  MAYBE_ASSIGNMENT, FLAG_ELIF | FLAG_ELSE | FLAG_FI },
		{ "elif",  RES_ELIF,  MAYBE_ASSIGNMENT, FLAG_THEN },
		{ "else",  RES_ELSE,  MAYBE_ASSIGNMENT, FLAG_FI   },
		{ "fi",    RES_FI,    NOT_ASSIGNMENT  , FLAG_END  },
# endif
# if ENABLE_HUSH_LOOPS
		{ "for",   RES_FOR,   NOT_ASSIGNMENT  , FLAG_IN | FLAG_DO | FLAG_START },
		{ "while", RES_WHILE, MAYBE_ASSIGNMENT, FLAG_DO | FLAG_START },
		{ "until", RES_UNTIL, MAYBE_ASSIGNMENT, FLAG_DO | FLAG_START },
		{ "in",    RES_IN,    NOT_ASSIGNMENT  , FLAG_DO   },
		{ "do",    RES_DO,    MAYBE_ASSIGNMENT, FLAG_DONE },
		{ "done",  RES_DONE,  NOT_ASSIGNMENT  , FLAG_END  },
# endif
# if ENABLE_HUSH_CASE
		{ "case",  RES_CASE,  NOT_ASSIGNMENT  , FLAG_MATCH | FLAG_START },
		{ "esac",  RES_ESAC,  NOT_ASSIGNMENT  , FLAG_END  },
# endif
	};
	const struct reserved_combo *r;

	for (r = reserved_list; r < reserved_list + ARRAY_SIZE(reserved_list); r++) {
		if (strcmp(word->data, r->literal) == 0)
			return r;
	}
	return NULL;
}
/* Return 0: not a keyword, 1: keyword
 */
static int reserved_word(o_string *word, struct parse_context *ctx)
{
# if ENABLE_HUSH_CASE
	static const struct reserved_combo reserved_match = {
		"",        RES_MATCH, NOT_ASSIGNMENT , FLAG_MATCH | FLAG_ESAC
	};
# endif
	const struct reserved_combo *r;

	if (word->has_quoted_part)
		return 0;
	r = match_reserved_word(word);
	if (!r)
		return 0;

	debug_printf("found reserved word %s, res %d\n", r->literal, r->res);
# if ENABLE_HUSH_CASE
	if (r->res == RES_IN && ctx->ctx_res_w == RES_CASE_IN) {
		/* "case word IN ..." - IN part starts first MATCH part */
		r = &reserved_match;
	} else
# endif
	if (r->flag == 0) { /* '!' */
		if (ctx->ctx_inverted) { /* bash doesn't accept '! ! true' */
			syntax_error("! ! command");
			ctx->ctx_res_w = RES_SNTX;
		}
		ctx->ctx_inverted = 1;
		return 1;
	}
	if (r->flag & FLAG_START) {
		struct parse_context *old;

		old = xmemdup(ctx, sizeof(*ctx));
		debug_printf_parse("push stack %p\n", old);
		initialize_context(ctx);
		ctx->stack = old;
	} else if (/*ctx->ctx_res_w == RES_NONE ||*/ !(ctx->old_flag & (1 << r->res))) {
		syntax_error_at(word->data);
		ctx->ctx_res_w = RES_SNTX;
		return 1;
	} else {
		/* "{...} fi" is ok. "{...} if" is not
		 * Example:
		 * if { echo foo; } then { echo bar; } fi */
		if (ctx->command->group)
			done_pipe(ctx, PIPE_SEQ);
	}

	ctx->ctx_res_w = r->res;
	ctx->old_flag = r->flag;
	word->o_assignment = r->assignment_flag;
	debug_printf_parse("word->o_assignment='%s'\n", assignment_flag[word->o_assignment]);

	if (ctx->old_flag & FLAG_END) {
		struct parse_context *old;

		done_pipe(ctx, PIPE_SEQ);
		debug_printf_parse("pop stack %p\n", ctx->stack);
		old = ctx->stack;
		old->command->group = ctx->list_head;
		old->command->cmd_type = CMD_NORMAL;
# if !BB_MMU
		/* At this point, the compound command's string is in
		 * ctx->as_string... except for the leading keyword!
		 * Consider this example: "echo a | if true; then echo a; fi"
		 * ctx->as_string will contain "true; then echo a; fi",
		 * with "if " remaining in old->as_string!
		 */
		{
			char *str;
			int len = old->as_string.length;
			/* Concatenate halves */
			o_addstr(&old->as_string, ctx->as_string.data);
			o_free_unsafe(&ctx->as_string);
			/* Find where leading keyword starts in first half */
			str = old->as_string.data + len;
			if (str > old->as_string.data)
				str--; /* skip whitespace after keyword */
			while (str > old->as_string.data && isalpha(str[-1]))
				str--;
			/* Ugh, we're done with this horrid hack */
			old->command->group_as_string = xstrdup(str);
			debug_printf_parse("pop, remembering as:'%s'\n",
					old->command->group_as_string);
		}
# endif
		*ctx = *old;   /* physical copy */
		free(old);
	}
	return 1;
}
#endif /* HAS_KEYWORDS */

/* Word is complete, look at it and update parsing context.
 * Normal return is 0. Syntax errors return 1.
 * Note: on return, word is reset, but not o_free'd!
 */
static int done_word(o_string *word, struct parse_context *ctx)
{
	struct command *command = ctx->command;

	debug_printf_parse("done_word entered: '%s' %p\n", word->data, command);
	if (word->length == 0 && !word->has_quoted_part) {
		debug_printf_parse("done_word return 0: true null, ignored\n");
		return 0;
	}

	if (ctx->pending_redirect) {
		/* We do not glob in e.g. >*.tmp case. bash seems to glob here
		 * only if run as "bash", not "sh" */
		/* http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html
		 * "2.7 Redirection
		 * ...the word that follows the redirection operator
		 * shall be subjected to tilde expansion, parameter expansion,
		 * command substitution, arithmetic expansion, and quote
		 * removal. Pathname expansion shall not be performed
		 * on the word by a non-interactive shell; an interactive
		 * shell may perform it, but shall do so only when
		 * the expansion would result in one word."
		 */
		ctx->pending_redirect->rd_filename = xstrdup(word->data);
		/* Cater for >\file case:
		 * >\a creates file a; >\\a, >"\a", >"\\a" create file \a
		 * Same with heredocs:
		 * for <<\H delim is H; <<\\H, <<"\H", <<"\\H" - \H
		 */
		if (ctx->pending_redirect->rd_type == REDIRECT_HEREDOC) {
			unbackslash(ctx->pending_redirect->rd_filename);
			/* Is it <<"HEREDOC"? */
			if (word->has_quoted_part) {
				ctx->pending_redirect->rd_dup |= HEREDOC_QUOTED;
			}
		}
		debug_printf_parse("word stored in rd_filename: '%s'\n", word->data);
		ctx->pending_redirect = NULL;
	} else {
#if HAS_KEYWORDS
# if ENABLE_HUSH_CASE
		if (ctx->ctx_dsemicolon
		 && strcmp(word->data, "esac") != 0 /* not "... pattern) cmd;; esac" */
		) {
			/* already done when ctx_dsemicolon was set to 1: */
			/* ctx->ctx_res_w = RES_MATCH; */
			ctx->ctx_dsemicolon = 0;
		} else
# endif
		if (!command->argv /* if it's the first word... */
# if ENABLE_HUSH_LOOPS
		 && ctx->ctx_res_w != RES_FOR /* ...not after FOR or IN */
		 && ctx->ctx_res_w != RES_IN
# endif
# if ENABLE_HUSH_CASE
		 && ctx->ctx_res_w != RES_CASE
# endif
		) {
			int reserved = reserved_word(word, ctx);
			debug_printf_parse("checking for reserved-ness: %d\n", reserved);
			if (reserved) {
				o_reset_to_empty_unquoted(word);
				debug_printf_parse("done_word return %d\n",
						(ctx->ctx_res_w == RES_SNTX));
				return (ctx->ctx_res_w == RES_SNTX);
			}
# if BASH_TEST2
			if (strcmp(word->data, "[[") == 0) {
				command->cmd_type = CMD_SINGLEWORD_NOGLOB;
			}
			/* fall through */
# endif
		}
#endif
		if (command->group) {
			/* "{ echo foo; } echo bar" - bad */
			syntax_error_at(word->data);
			debug_printf_parse("done_word return 1: syntax error, "
					"groups and arglists don't mix\n");
			return 1;
		}

		/* If this word wasn't an assignment, next ones definitely
		 * can't be assignments. Even if they look like ones. */
		if (word->o_assignment != DEFINITELY_ASSIGNMENT
		 && word->o_assignment != WORD_IS_KEYWORD
		) {
			word->o_assignment = NOT_ASSIGNMENT;
		} else {
			if (word->o_assignment == DEFINITELY_ASSIGNMENT) {
				command->assignment_cnt++;
				debug_printf_parse("++assignment_cnt=%d\n", command->assignment_cnt);
			}
			debug_printf_parse("word->o_assignment was:'%s'\n", assignment_flag[word->o_assignment]);
			word->o_assignment = MAYBE_ASSIGNMENT;
		}
		debug_printf_parse("word->o_assignment='%s'\n", assignment_flag[word->o_assignment]);

		if (word->has_quoted_part
		 /* optimization: and if it's ("" or '') or ($v... or `cmd`...): */
		 && (word->data[0] == '\0' || word->data[0] == SPECIAL_VAR_SYMBOL)
		 /* (otherwise it's known to be not empty and is already safe) */
		) {
			/* exclude "$@" - it can expand to no word despite "" */
			char *p = word->data;
			while (p[0] == SPECIAL_VAR_SYMBOL
			    && (p[1] & 0x7f) == '@'
			    && p[2] == SPECIAL_VAR_SYMBOL
			) {
				p += 3;
			}
		}
		command->argv = add_string_to_strings(command->argv, xstrdup(word->data));
		debug_print_strings("word appended to argv", command->argv);
	}

#if ENABLE_HUSH_LOOPS
	if (ctx->ctx_res_w == RES_FOR) {
		if (word->has_quoted_part
		 || !is_well_formed_var_name(command->argv[0], '\0')
		) {
			/* bash says just "not a valid identifier" */
			syntax_error("not a valid identifier in for");
			return 1;
		}
		/* Force FOR to have just one word (variable name) */
		/* NB: basically, this makes hush see "for v in ..."
		 * syntax as if it is "for v; in ...". FOR and IN become
		 * two pipe structs in parse tree. */
		done_pipe(ctx, PIPE_SEQ);
	}
#endif
#if ENABLE_HUSH_CASE
	/* Force CASE to have just one word */
	if (ctx->ctx_res_w == RES_CASE) {
		done_pipe(ctx, PIPE_SEQ);
	}
#endif

	o_reset_to_empty_unquoted(word);

	debug_printf_parse("done_word return 0\n");
	return 0;
}


/* Peek ahead in the input to find out if we have a "&n" construct,
 * as in "2>&1", that represents duplicating a file descriptor.
 * Return:
 * REDIRFD_CLOSE if >&- "close fd" construct is seen,
 * REDIRFD_SYNTAX_ERR if syntax error,
 * REDIRFD_TO_FILE if no & was seen,
 * or the number found.
 */
#if BB_MMU
#define parse_redir_right_fd(as_string, input) \
	parse_redir_right_fd(input)
#endif
static int parse_redir_right_fd(o_string *as_string, struct in_str *input)
{
	int ch, d, ok;

	ch = i_peek(input);
	if (ch != '&')
		return REDIRFD_TO_FILE;

	ch = i_getch(input);  /* get the & */
	nommu_addchr(as_string, ch);
	ch = i_peek(input);
	if (ch == '-') {
		ch = i_getch(input);
		nommu_addchr(as_string, ch);
		return REDIRFD_CLOSE;
	}
	d = 0;
	ok = 0;
	while (ch != EOF && isdigit(ch)) {
		d = d*10 + (ch-'0');
		ok = 1;
		ch = i_getch(input);
		nommu_addchr(as_string, ch);
		ch = i_peek(input);
	}
	if (ok) return d;

//TODO: this is the place to catch ">&file" bashism (redirect both fd 1 and 2)

	bb_error_msg("ambiguous redirect");
	return REDIRFD_SYNTAX_ERR;
}

/* Return code is 0 normal, 1 if a syntax error is detected
 */
static int parse_redirect(struct parse_context *ctx,
		int fd,
		redir_type style,
		struct in_str *input)
{
	struct command *command = ctx->command;
	struct redir_struct *redir;
	struct redir_struct **redirp;
	int dup_num;

	dup_num = REDIRFD_TO_FILE;
	if (style != REDIRECT_HEREDOC) {
		/* Check for a '>&1' type redirect */
		dup_num = parse_redir_right_fd(&ctx->as_string, input);
		if (dup_num == REDIRFD_SYNTAX_ERR)
			return 1;
	} else {
		int ch = i_peek(input);
		dup_num = (ch == '-'); /* HEREDOC_SKIPTABS bit is 1 */
		if (dup_num) { /* <<-... */
			ch = i_getch(input);
			nommu_addchr(&ctx->as_string, ch);
			ch = i_peek(input);
		}
	}

	if (style == REDIRECT_OVERWRITE && dup_num == REDIRFD_TO_FILE) {
		int ch = i_peek(input);
		if (ch == '|') {
			/* >|FILE redirect ("clobbering" >).
			 * Since we do not support "set -o noclobber" yet,
			 * >| and > are the same for now. Just eat |.
			 */
			ch = i_getch(input);
			nommu_addchr(&ctx->as_string, ch);
		}
	}

	/* Create a new redir_struct and append it to the linked list */
	redirp = &command->redirects;
	while ((redir = *redirp) != NULL) {
		redirp = &(redir->next);
	}
	*redirp = redir = xzalloc(sizeof(*redir));
	/* redir->next = NULL; */
	/* redir->rd_filename = NULL; */
	redir->rd_type = style;
	redir->rd_fd = (fd == -1) ? redir_table[style].default_fd : fd;

	debug_printf_parse("redirect type %d %s\n", redir->rd_fd,
				redir_table[style].descrip);

	redir->rd_dup = dup_num;
	if (style != REDIRECT_HEREDOC && dup_num != REDIRFD_TO_FILE) {
		/* Erik had a check here that the file descriptor in question
		 * is legit; I postpone that to "run time"
		 * A "-" representation of "close me" shows up as a -3 here */
		debug_printf_parse("duplicating redirect '%d>&%d'\n",
				redir->rd_fd, redir->rd_dup);
	} else {
#if 0		/* Instead we emit error message at run time */
		if (ctx->pending_redirect) {
			/* For example, "cmd > <file" */
			syntax_error("invalid redirect");
		}
#endif
		/* Set ctx->pending_redirect, so we know what to do at the
		 * end of the next parsed word. */
		ctx->pending_redirect = redir;
	}
	return 0;
}

/* If a redirect is immediately preceded by a number, that number is
 * supposed to tell which file descriptor to redirect.  This routine
 * looks for such preceding numbers.  In an ideal world this routine
 * needs to handle all the following classes of redirects...
 *     echo 2>foo     # redirects fd  2 to file "foo", nothing passed to echo
 *     echo 49>foo    # redirects fd 49 to file "foo", nothing passed to echo
 *     echo -2>foo    # redirects fd  1 to file "foo",    "-2" passed to echo
 *     echo 49x>foo   # redirects fd  1 to file "foo",   "49x" passed to echo
 *
 * http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html
 * "2.7 Redirection
 * ... If n is quoted, the number shall not be recognized as part of
 * the redirection expression. For example:
 * echo \2>a
 * writes the character 2 into file a"
 * We are getting it right by setting ->has_quoted_part on any \<char>
 *
 * A -1 return means no valid number was found,
 * the caller should use the appropriate default for this redirection.
 */
static int redirect_opt_num(o_string *o)
{
	int num;

	if (o->data == NULL)
		return -1;
	num = bb_strtou(o->data, NULL, 10);
	if (errno || num < 0)
		return -1;
	o_reset_to_empty_unquoted(o);
	return num;
}

#if BB_MMU
#define fetch_till_str(as_string, input, word, skip_tabs) \
	fetch_till_str(input, word, skip_tabs)
#endif
static char *fetch_till_str(o_string *as_string,
		struct in_str *input,
		const char *word,
		int heredoc_flags)
{
	o_string heredoc = NULL_O_STRING;
	unsigned past_EOL;
	int prev = 0; /* not \ */
	int ch;

	goto jump_in;

	while (1) {
		ch = i_getch(input);
		if (ch != EOF)
			nommu_addchr(as_string, ch);
		if (ch == '\n' || ch == EOF) {
 check_heredoc_end:
			if ((heredoc_flags & HEREDOC_QUOTED) || prev != '\\') {
				if (strcmp(heredoc.data + past_EOL, word) == 0) {
					heredoc.data[past_EOL] = '\0';
					debug_printf_parse("parsed heredoc '%s'\n", heredoc.data);
					return heredoc.data;
				}
				if (ch == '\n') {
					/* This is a new line.
					 * Remember position and backslash-escaping status.
					 */
					o_addchr(&heredoc, ch);
					prev = ch;
 jump_in:
					past_EOL = heredoc.length;
					/* Get 1st char of next line, possibly skipping leading tabs */
					do {
						ch = i_getch(input);
						if (ch != EOF)
							nommu_addchr(as_string, ch);
					} while ((heredoc_flags & HEREDOC_SKIPTABS) && ch == '\t');
					/* If this immediately ended the line,
					 * go back to end-of-line checks.
					 */
					if (ch == '\n')
						goto check_heredoc_end;
				}
			}
		}
		if (ch == EOF) {
			o_free_unsafe(&heredoc);
			return NULL;
		}
		o_addchr(&heredoc, ch);
		nommu_addchr(as_string, ch);
		if (prev == '\\' && ch == '\\')
			/* Correctly handle foo\\<eol> (not a line cont.) */
			prev = 0; /* not \ */
		else
			prev = ch;
	}
}

/* Look at entire parse tree for not-yet-loaded REDIRECT_HEREDOCs
 * and load them all. There should be exactly heredoc_cnt of them.
 */
static int fetch_heredocs(int heredoc_cnt, struct parse_context *ctx, struct in_str *input)
{
	struct pipe *pi = ctx->list_head;

	while (pi && heredoc_cnt) {
		int i;
		struct command *cmd = pi->cmds;

		debug_printf_parse("fetch_heredocs: num_cmds:%d cmd argv0:'%s'\n",
				pi->num_cmds,
				cmd->argv ? cmd->argv[0] : "NONE");
		for (i = 0; i < pi->num_cmds; i++) {
			struct redir_struct *redir = cmd->redirects;

			debug_printf_parse("fetch_heredocs: %d cmd argv0:'%s'\n",
					i, cmd->argv ? cmd->argv[0] : "NONE");
			while (redir) {
				if (redir->rd_type == REDIRECT_HEREDOC) {
					char *p;

					redir->rd_type = REDIRECT_HEREDOC2;
					/* redir->rd_dup is (ab)used to indicate <<- */
					p = fetch_till_str(&ctx->as_string, input,
							redir->rd_filename, redir->rd_dup);
					if (!p) {
						syntax_error("unexpected EOF in here document");
						return 1;
					}
					free(redir->rd_filename);
					redir->rd_filename = p;
					heredoc_cnt--;
				}
				redir = redir->next;
			}
			cmd++;
		}
		pi = pi->next;
	}
#if 0
	/* Should be 0. If it isn't, it's a parse error */
	if (heredoc_cnt)
		bb_error_msg_and_die("heredoc BUG 2");
#endif
	return 0;
}


static int run_list(struct pipe *pi);
#if BB_MMU
#define parse_stream(pstring, input, end_trigger) \
	parse_stream(input, end_trigger)
#endif
static struct pipe *parse_stream(char **pstring,
		struct in_str *input,
		int end_trigger);


#if !ENABLE_HUSH_FUNCTIONS
#define parse_group(dest, ctx, input, ch) \
	parse_group(ctx, input, ch)
#endif
static int parse_group(o_string *dest, struct parse_context *ctx,
	struct in_str *input, int ch)
{
	/* dest contains characters seen prior to ( or {.
	 * Typically it's empty, but for function defs,
	 * it contains function name (without '()'). */
	struct pipe *pipe_list;
	int endch;
	struct command *command = ctx->command;

	debug_printf_parse("parse_group entered\n");
#if ENABLE_HUSH_FUNCTIONS
	if (ch == '(' && !dest->has_quoted_part) {
		if (dest->length)
			if (done_word(dest, ctx))
				return 1;
		if (!command->argv)
			goto skip; /* (... */
		if (command->argv[1]) { /* word word ... (... */
			syntax_error_unexpected_ch('(');
			return 1;
		}
		/* it is "word(..." or "word (..." */
		do
			ch = i_getch(input);
		while (ch == ' ' || ch == '\t');
		if (ch != ')') {
			syntax_error_unexpected_ch(ch);
			return 1;
		}
		nommu_addchr(&ctx->as_string, ch);
		do
			ch = i_getch(input);
		while (ch == ' ' || ch == '\t' || ch == '\n');
		if (ch != '{') {
			syntax_error_unexpected_ch(ch);
			return 1;
		}
		nommu_addchr(&ctx->as_string, ch);
		command->cmd_type = CMD_FUNCDEF;
		goto skip;
	}
#endif

#if 0 /* Prevented by caller */
	if (command->argv /* word [word]{... */
	 || dest->length /* word{... */
	 || dest->has_quoted_part /* ""{... */
	) {
		syntax_error(NULL);
		debug_printf_parse("parse_group return 1: "
			"syntax error, groups and arglists don't mix\n");
		return 1;
	}
#endif

#if ENABLE_HUSH_FUNCTIONS
 skip:
#endif
	endch = '}';
	if (ch == '(') {
		endch = ')';
		command->cmd_type = CMD_SUBSHELL;
	} else {
		/* bash does not allow "{echo...", requires whitespace */
		ch = i_peek(input);
		if (ch != ' ' && ch != '\t' && ch != '\n'
		 && ch != '('	/* but "{(..." is allowed (without whitespace) */
		) {
			syntax_error_unexpected_ch(ch);
			return 1;
		}
		if (ch != '(') {
			ch = i_getch(input);
			nommu_addchr(&ctx->as_string, ch);
		}
	}

	{
#if BB_MMU
# define as_string NULL
#else
		char *as_string = NULL;
#endif
		pipe_list = parse_stream(&as_string, input, endch);
#if !BB_MMU
		if (as_string)
			o_addstr(&ctx->as_string, as_string);
#endif
		/* empty ()/{} or parse error? */
		if (!pipe_list || pipe_list == ERR_PTR) {
			/* parse_stream already emitted error msg */
			if (!BB_MMU)
				free(as_string);
			debug_printf_parse("parse_group return 1: "
				"parse_stream returned %p\n", pipe_list);
			return 1;
		}
		command->group = pipe_list;
#if !BB_MMU
		as_string[strlen(as_string) - 1] = '\0'; /* plink ')' or '}' */
		command->group_as_string = as_string;
		debug_printf_parse("end of group, remembering as:'%s'\n",
				command->group_as_string);
#endif
#undef as_string
	}
	debug_printf_parse("parse_group return 0\n");
	return 0;
	/* command remains "open", available for possible redirects */
}

static int i_getch_and_eat_bkslash_nl(struct in_str *input)
{
	for (;;) {
		int ch, ch2;

		ch = i_getch(input);
		if (ch != '\\')
			return ch;
		ch2 = i_peek(input);
		if (ch2 != '\n')
			return ch;
		/* backslash+newline, skip it */
		i_getch(input);
	}
}

static int i_peek_and_eat_bkslash_nl(struct in_str *input)
{
	for (;;) {
		int ch, ch2;

		ch = i_peek(input);
		if (ch != '\\')
			return ch;
		ch2 = i_peek2(input);
		if (ch2 != '\n')
			return ch;
		/* backslash+newline, skip it */
		i_getch(input);
		i_getch(input);
	}
}

#if ENABLE_HUSH_TICK || ENABLE_FEATURE_SH_MATH || ENABLE_HUSH_DOLLAR_OPS
/* Subroutines for copying $(...) and `...` things */
static int add_till_backquote(o_string *dest, struct in_str *input, int in_dquote);
/* '...' */
static int add_till_single_quote(o_string *dest, struct in_str *input)
{
	while (1) {
		int ch = i_getch(input);
		if (ch == EOF) {
			syntax_error_unterm_ch('\'');
			return 0;
		}
		if (ch == '\'')
			return 1;
		o_addchr(dest, ch);
	}
}
/* "...\"...`..`...." - do we need to handle "...$(..)..." too? */
static int add_till_double_quote(o_string *dest, struct in_str *input)
{
	while (1) {
		int ch = i_getch(input);
		if (ch == EOF) {
			syntax_error_unterm_ch('"');
			return 0;
		}
		if (ch == '"')
			return 1;
		if (ch == '\\') {  /* \x. Copy both chars. */
			o_addchr(dest, ch);
			ch = i_getch(input);
		}
		o_addchr(dest, ch);
		if (ch == '`') {
			if (!add_till_backquote(dest, input, /*in_dquote:*/ 1))
				return 0;
			o_addchr(dest, ch);
			continue;
		}
		//if (ch == '$') ...
	}
}
/* Process `cmd` - copy contents until "`" is seen. Complicated by
 * \` quoting.
 * "Within the backquoted style of command substitution, backslash
 * shall retain its literal meaning, except when followed by: '$', '`', or '\'.
 * The search for the matching backquote shall be satisfied by the first
 * backquote found without a preceding backslash; during this search,
 * if a non-escaped backquote is encountered within a shell comment,
 * a here-document, an embedded command substitution of the $(command)
 * form, or a quoted string, undefined results occur. A single-quoted
 * or double-quoted string that begins, but does not end, within the
 * "`...`" sequence produces undefined results."
 * Example                               Output
 * echo `echo '\'TEST\`echo ZZ\`BEST`    \TESTZZBEST
 */
static int add_till_backquote(o_string *dest, struct in_str *input, int in_dquote)
{
	while (1) {
		int ch = i_getch(input);
		if (ch == '`')
			return 1;
		if (ch == '\\') {
			/* \x. Copy both unless it is \`, \$, \\ and maybe \" */
			ch = i_getch(input);
			if (ch != '`'
			 && ch != '$'
			 && ch != '\\'
			 && (!in_dquote || ch != '"')
			) {
				o_addchr(dest, '\\');
			}
		}
		if (ch == EOF) {
			syntax_error_unterm_ch('`');
			return 0;
		}
		o_addchr(dest, ch);
	}
}
/* Process $(cmd) - copy contents until ")" is seen. Complicated by
 * quoting and nested ()s.
 * "With the $(command) style of command substitution, all characters
 * following the open parenthesis to the matching closing parenthesis
 * constitute the command. Any valid shell script can be used for command,
 * except a script consisting solely of redirections which produces
 * unspecified results."
 * Example                              Output
 * echo $(echo '(TEST)' BEST)           (TEST) BEST
 * echo $(echo 'TEST)' BEST)            TEST) BEST
 * echo $(echo \(\(TEST\) BEST)         ((TEST) BEST
 *
 * Also adapted to eat ${var%...} and $((...)) constructs, since ... part
 * can contain arbitrary constructs, just like $(cmd).
 * In bash compat mode, it needs to also be able to stop on ':' or '/'
 * for ${var:N[:M]} and ${var/P[/R]} parsing.
 */
#define DOUBLE_CLOSE_CHAR_FLAG 0x80
static int add_till_closing_bracket(o_string *dest, struct in_str *input, unsigned end_ch)
{
	int ch;
	char dbl = end_ch & DOUBLE_CLOSE_CHAR_FLAG;
# if BASH_SUBSTR || BASH_PATTERN_SUBST
	char end_char2 = end_ch >> 8;
# endif
	end_ch &= (DOUBLE_CLOSE_CHAR_FLAG - 1);

	while (1) {
		ch = i_getch(input);
		if (ch == EOF) {
			syntax_error_unterm_ch(end_ch);
			return 0;
		}
		if (ch == end_ch
# if BASH_SUBSTR || BASH_PATTERN_SUBST
			|| ch == end_char2
# endif
		) {
			if (!dbl)
				break;
			/* we look for closing )) of $((EXPR)) */
			if (i_peek_and_eat_bkslash_nl(input) == end_ch) {
				i_getch(input); /* eat second ')' */
				break;
			}
		}
		o_addchr(dest, ch);
		if (ch == '(' || ch == '{') {
			ch = (ch == '(' ? ')' : '}');
			if (!add_till_closing_bracket(dest, input, ch))
				return 0;
			o_addchr(dest, ch);
			continue;
		}
		if (ch == '\'') {
			if (!add_till_single_quote(dest, input))
				return 0;
			o_addchr(dest, ch);
			continue;
		}
		if (ch == '"') {
			if (!add_till_double_quote(dest, input))
				return 0;
			o_addchr(dest, ch);
			continue;
		}
		if (ch == '`') {
			if (!add_till_backquote(dest, input, /*in_dquote:*/ 0))
				return 0;
			o_addchr(dest, ch);
			continue;
		}
		if (ch == '\\') {
			/* \x. Copy verbatim. Important for  \(, \) */
			ch = i_getch(input);
			if (ch == EOF) {
				syntax_error_unterm_ch(')');
				return 0;
			}
#if 0
			if (ch == '\n') {
				/* "backslash+newline", ignore both */
				o_delchr(dest); /* undo insertion of '\' */
				continue;
			}
#endif
			o_addchr(dest, ch);
			continue;
		}
	}
	return ch;
}
#endif /* ENABLE_HUSH_TICK || ENABLE_FEATURE_SH_MATH || ENABLE_HUSH_DOLLAR_OPS */

/* Return code: 0 for OK, 1 for syntax error */
#if BB_MMU
#define parse_dollar(as_string, dest, input, quote_mask) \
	parse_dollar(dest, input, quote_mask)
#define as_string NULL
#endif
static int parse_dollar(o_string *as_string,
		o_string *dest,
		struct in_str *input, unsigned char quote_mask)
{
	int ch = i_peek_and_eat_bkslash_nl(input);  /* first character after the $ */

	debug_printf_parse("parse_dollar entered: ch='%c'\n", ch);
	if (isalpha(ch)) {
		ch = i_getch(input);
		nommu_addchr(as_string, ch);
 make_var:
		o_addchr(dest, SPECIAL_VAR_SYMBOL);
		while (1) {
			debug_printf_parse(": '%c'\n", ch);
			o_addchr(dest, ch | quote_mask);
			quote_mask = 0;
			ch = i_peek_and_eat_bkslash_nl(input);
			if (!isalnum(ch) && ch != '_') {
				/* End of variable name reached */
				break;
			}
			ch = i_getch(input);
			nommu_addchr(as_string, ch);
		}
		o_addchr(dest, SPECIAL_VAR_SYMBOL);
	} else if (isdigit(ch)) {
 make_one_char_var:
		ch = i_getch(input);
		nommu_addchr(as_string, ch);
		o_addchr(dest, SPECIAL_VAR_SYMBOL);
		debug_printf_parse(": '%c'\n", ch);
		o_addchr(dest, ch | quote_mask);
		o_addchr(dest, SPECIAL_VAR_SYMBOL);
	} else switch (ch) {
	case '$': /* pid */
	case '!': /* last bg pid */
	case '?': /* last exit code */
	case '#': /* number of args */
	case '*': /* args */
	case '@': /* args */
		goto make_one_char_var;
	case '{': {
		char len_single_ch;

		o_addchr(dest, SPECIAL_VAR_SYMBOL);

		ch = i_getch(input); /* eat '{' */
		nommu_addchr(as_string, ch);

		ch = i_getch_and_eat_bkslash_nl(input); /* first char after '{' */
		/* It should be ${?}, or ${#var},
		 * or even ${?+subst} - operator acting on a special variable,
		 * or the beginning of variable name.
		 */
		if (ch == EOF
		 || (!strchr(_SPECIAL_VARS_STR, ch) && !isalnum(ch)) /* not one of those */
		) {
 bad_dollar_syntax:
			syntax_error_unterm_str("${name}");
			debug_printf_parse("parse_dollar return 0: unterminated ${name}\n");
			return 0;
		}
		nommu_addchr(as_string, ch);
		len_single_ch = ch;
		ch |= quote_mask;

		/* It's possible to just call add_till_closing_bracket() at this point.
		 * However, this regresses some of our testsuite cases
		 * which check invalid constructs like ${%}.
		 * Oh well... let's check that the var name part is fine... */

		while (1) {
			unsigned pos;

			o_addchr(dest, ch);
			debug_printf_parse(": '%c'\n", ch);

			ch = i_getch(input);
			nommu_addchr(as_string, ch);
			if (ch == '}')
				break;

			if (!isalnum(ch) && ch != '_') {
				unsigned end_ch;
				unsigned char last_ch;
				/* handle parameter expansions
				 * http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_06_02
				 */
				if (!strchr(VAR_SUBST_OPS, ch)) { /* ${var<bad_char>... */
					if (len_single_ch != '#'
					/*|| !strchr(SPECIAL_VARS_STR, ch) - disallow errors like ${#+} ? */
					 || i_peek(input) != '}'
					) {
						goto bad_dollar_syntax;
					}
					/* else: it's "length of C" ${#C} op,
					 * where C is a single char
					 * special var name, e.g. ${#!}.
					 */
				}
				/* Eat everything until closing '}' (or ':') */
				end_ch = '}';
				if (BASH_SUBSTR
				 && ch == ':'
				 && !strchr(MINUS_PLUS_EQUAL_QUESTION, i_peek(input))
				) {
					/* It's ${var:N[:M]} thing */
					end_ch = '}' * 0x100 + ':';
				}
				if (BASH_PATTERN_SUBST
				 && ch == '/'
				) {
					/* It's ${var/[/]pattern[/repl]} thing */
					if (i_peek(input) == '/') { /* ${var//pattern[/repl]}? */
						i_getch(input);
						nommu_addchr(as_string, '/');
						ch = '\\';
					}
					end_ch = '}' * 0x100 + '/';
				}
				o_addchr(dest, ch);
 again:
				if (!BB_MMU)
					pos = dest->length;
#if ENABLE_HUSH_DOLLAR_OPS
				last_ch = add_till_closing_bracket(dest, input, end_ch);
				if (last_ch == 0) /* error? */
					return 0;
#else
#error Simple code to only allow ${var} is not implemented
#endif
				if (as_string) {
					o_addstr(as_string, dest->data + pos);
					o_addchr(as_string, last_ch);
				}

				if ((BASH_SUBSTR || BASH_PATTERN_SUBST)
					 && (end_ch & 0xff00)
				) {
					/* close the first block: */
					o_addchr(dest, SPECIAL_VAR_SYMBOL);
					/* while parsing N from ${var:N[:M]}
					 * or pattern from ${var/[/]pattern[/repl]} */
					if ((end_ch & 0xff) == last_ch) {
						/* got ':' or '/'- parse the rest */
						end_ch = '}';
						goto again;
					}
					/* got '}' */
					if (BASH_SUBSTR && end_ch == '}' * 0x100 + ':') {
						/* it's ${var:N} - emulate :999999999 */
						o_addstr(dest, "999999999");
					} /* else: it's ${var/[/]pattern} */
				}
				break;
			}
			len_single_ch = 0; /* it can't be ${#C} op */
		}
		o_addchr(dest, SPECIAL_VAR_SYMBOL);
		break;
	}
#if ENABLE_FEATURE_SH_MATH || ENABLE_HUSH_TICK
	case '(': {
		unsigned pos;

		ch = i_getch(input);
		nommu_addchr(as_string, ch);
# if ENABLE_FEATURE_SH_MATH
		if (i_peek_and_eat_bkslash_nl(input) == '(') {
			ch = i_getch(input);
			nommu_addchr(as_string, ch);
			o_addchr(dest, SPECIAL_VAR_SYMBOL);
			o_addchr(dest, /*quote_mask |*/ '+');
			if (!BB_MMU)
				pos = dest->length;
			if (!add_till_closing_bracket(dest, input, ')' | DOUBLE_CLOSE_CHAR_FLAG))
				return 0; /* error */
			if (as_string) {
				o_addstr(as_string, dest->data + pos);
				o_addchr(as_string, ')');
				o_addchr(as_string, ')');
			}
			o_addchr(dest, SPECIAL_VAR_SYMBOL);
			break;
		}
# endif
# if ENABLE_HUSH_TICK
		o_addchr(dest, SPECIAL_VAR_SYMBOL);
		o_addchr(dest, quote_mask | '`');
		if (!BB_MMU)
			pos = dest->length;
		if (!add_till_closing_bracket(dest, input, ')'))
			return 0; /* error */
		if (as_string) {
			o_addstr(as_string, dest->data + pos);
			o_addchr(as_string, ')');
		}
		o_addchr(dest, SPECIAL_VAR_SYMBOL);
# endif
		break;
	}
#endif
	case '_':
		ch = i_getch(input);
		nommu_addchr(as_string, ch);
		ch = i_peek_and_eat_bkslash_nl(input);
		if (isalnum(ch)) { /* it's $_name or $_123 */
			ch = '_';
			goto make_var;
		}
		/* else: it's $_ */
	/* TODO: $_ and $-: */
	/* $_ Shell or shell script name; or last argument of last command
	 * (if last command wasn't a pipe; if it was, bash sets $_ to "");
	 * but in command's env, set to full pathname used to invoke it */
	/* $- Option flags set by set builtin or shell options (-i etc) */
	default:
		o_addQchr(dest, '$');
	}
	debug_printf_parse("parse_dollar return 1 (ok)\n");
	return 1;
#undef as_string
}

#if BB_MMU
# if BASH_PATTERN_SUBST
#define encode_string(as_string, dest, input, dquote_end, process_bkslash) \
	encode_string(dest, input, dquote_end, process_bkslash)
# else
/* only ${var/pattern/repl} (its pattern part) needs additional mode */
#define encode_string(as_string, dest, input, dquote_end, process_bkslash) \
	encode_string(dest, input, dquote_end)
# endif
#define as_string NULL

#else /* !MMU */

# if BASH_PATTERN_SUBST
/* all parameters are needed, no macro tricks */
# else
#define encode_string(as_string, dest, input, dquote_end, process_bkslash) \
	encode_string(as_string, dest, input, dquote_end)
# endif
#endif
static int encode_string(o_string *as_string,
		o_string *dest,
		struct in_str *input,
		int dquote_end,
		int process_bkslash)
{
#if !BASH_PATTERN_SUBST
	const int process_bkslash = 1;
#endif
	int ch;
	int next;

 again:
	ch = i_getch(input);
	if (ch != EOF)
		nommu_addchr(as_string, ch);
	if (ch == dquote_end) { /* may be only '"' or EOF */
		debug_printf_parse("encode_string return 1 (ok)\n");
		return 1;
	}
	/* note: can't move it above ch == dquote_end check! */
	if (ch == EOF) {
		syntax_error_unterm_ch('"');
		return 0; /* error */
	}
	next = '\0';
	if (ch != '\n') {
		next = i_peek(input);
	}
	debug_printf_parse("\" ch=%c (%d) escape=%d\n",
			ch, ch, !!(dest->o_expflags & EXP_FLAG_ESC_GLOB_CHARS));
	if (process_bkslash && ch == '\\') {
		if (next == EOF) {
			syntax_error("\\<eof>");
			xfunc_die();
		}
		/* bash:
		 * "The backslash retains its special meaning [in "..."]
		 * only when followed by one of the following characters:
		 * $, `, ", \, or <newline>.  A double quote may be quoted
		 * within double quotes by preceding it with a backslash."
		 * NB: in (unquoted) heredoc, above does not apply to ",
		 * therefore we check for it by "next == dquote_end" cond.
		 */
		if (next == dquote_end || strchr("$`\\\n", next)) {
			ch = i_getch(input); /* eat next */
			if (ch == '\n')
				goto again; /* skip \<newline> */
		} /* else: ch remains == '\\', and we double it below: */
		o_addqchr(dest, ch); /* \c if c is a glob char, else just c */
		nommu_addchr(as_string, ch);
		goto again;
	}
	if (ch == '$') {
		if (!parse_dollar(as_string, dest, input, /*quote_mask:*/ 0x80)) {
			debug_printf_parse("encode_string return 0: "
					"parse_dollar returned 0 (error)\n");
			return 0;
		}
		goto again;
	}
#if ENABLE_HUSH_TICK
	if (ch == '`') {
		//unsigned pos = dest->length;
		o_addchr(dest, SPECIAL_VAR_SYMBOL);
		o_addchr(dest, 0x80 | '`');
		if (!add_till_backquote(dest, input, /*in_dquote:*/ dquote_end == '"'))
			return 0; /* error */
		o_addchr(dest, SPECIAL_VAR_SYMBOL);
		//debug_printf_subst("SUBST RES3 '%s'\n", dest->data + pos);
		goto again;
	}
#endif
	o_addQchr(dest, ch);
	goto again;
#undef as_string
}

/*
 * Scan input until EOF or end_trigger char.
 * Return a list of pipes to execute, or NULL on EOF
 * or if end_trigger character is met.
 * On syntax error, exit if shell is not interactive,
 * reset parsing machinery and start parsing anew,
 * or return ERR_PTR.
 */
static struct pipe *parse_stream(char **pstring,
		struct in_str *input,
		int end_trigger)
{
	struct parse_context ctx;
	o_string dest = NULL_O_STRING;
	int heredoc_cnt;

	/* Single-quote triggers a bypass of the main loop until its mate is
	 * found.  When recursing, quote state is passed in via dest->o_expflags.
	 */
	debug_printf_parse("parse_stream entered, end_trigger='%c'\n",
			end_trigger ? end_trigger : 'X');
	debug_enter();

	/* If very first arg is "" or '', dest.data may end up NULL.
	 * Preventing this: */
	o_addchr(&dest, '\0');
	dest.length = 0;

	/* We used to separate words on $IFS here. This was wrong.
	 * $IFS is used only for word splitting when $var is expanded,
	 * here we should use blank chars as separators, not $IFS
	 */

	if (MAYBE_ASSIGNMENT != 0)
		dest.o_assignment = MAYBE_ASSIGNMENT;
	initialize_context(&ctx);
	heredoc_cnt = 0;
	while (1) {
		const char *is_blank;
		const char *is_special;
		int ch;
		int next;
		int redir_fd;
		redir_type redir_style;

		ch = i_getch(input);
		debug_printf_parse(": ch=%c (%d) escape=%d\n",
				ch, ch, !!(dest.o_expflags & EXP_FLAG_ESC_GLOB_CHARS));
		if (ch == EOF) {
			struct pipe *pi;

			if (heredoc_cnt) {
				syntax_error_unterm_str("here document");
				goto parse_error;
			}
			if (end_trigger == ')') {
				syntax_error_unterm_ch('(');
				goto parse_error;
			}
			if (end_trigger == '}') {
				syntax_error_unterm_ch('{');
				goto parse_error;
			}

			if (done_word(&dest, &ctx)) {
				goto parse_error;
			}
			o_free(&dest);
			done_pipe(&ctx, PIPE_SEQ);
			pi = ctx.list_head;
			/* If we got nothing... */
			/* (this makes bare "&" cmd a no-op.
			 * bash says: "syntax error near unexpected token '&'") */
			if (pi->num_cmds == 0
			IF_HAS_KEYWORDS(&& pi->res_word == RES_NONE)
			) {
				free_pipe_list(pi);
				pi = NULL;
			}
#if !BB_MMU
			debug_printf_parse("as_string1 '%s'\n", ctx.as_string.data);
			if (pstring)
				*pstring = ctx.as_string.data;
			else
				o_free_unsafe(&ctx.as_string);
#endif
			debug_leave();
			debug_printf_parse("parse_stream return %p\n", pi);
			return pi;
		}
		nommu_addchr(&ctx.as_string, ch);

		next = '\0';
		if (ch != '\n')
			next = i_peek(input);

		is_special = "{}<>;&|()#'" /* special outside of "str" */
				"\\$\"" IF_HUSH_TICK("`"); /* always special */
		/* Are { and } special here? */
		if (ctx.command->argv /* word [word]{... - non-special */
		 || dest.length       /* word{... - non-special */
		 || dest.has_quoted_part     /* ""{... - non-special */
		 || (next != ';'             /* }; - special */
		    && next != ')'           /* }) - special */
		    && next != '('           /* {( - special */
		    && next != '&'           /* }& and }&& ... - special */
		    && next != '|'           /* }|| ... - special */
		    && !strchr(defifs, next) /* {word - non-special */
		    )
		) {
			/* They are not special, skip "{}" */
			is_special += 2;
		}
		is_special = strchr(is_special, ch);
		is_blank = strchr(defifs, ch);

		if (!is_special && !is_blank) { /* ordinary char */
 ordinary_char:
			o_addQchr(&dest, ch);
			if ((dest.o_assignment == MAYBE_ASSIGNMENT
			    || dest.o_assignment == WORD_IS_KEYWORD)
			 && ch == '='
			 && is_well_formed_var_name(dest.data, '=')
			) {
				dest.o_assignment = DEFINITELY_ASSIGNMENT;
				debug_printf_parse("dest.o_assignment='%s'\n", assignment_flag[dest.o_assignment]);
			}
			continue;
		}

		if (is_blank) {
			if (done_word(&dest, &ctx)) {
				goto parse_error;
			}
			if (ch == '\n') {
				/* Is this a case when newline is simply ignored?
				 * Some examples:
				 * "cmd | <newline> cmd ..."
				 * "case ... in <newline> word) ..."
				 */
				if (IS_NULL_CMD(ctx.command)
				 && dest.length == 0 && !dest.has_quoted_part
				) {
					/* This newline can be ignored. But...
					 * Without check #1, interactive shell
					 * ignores even bare <newline>,
					 * and shows the continuation prompt:
					 * ps1_prompt$ <enter>
					 * ps2> _   <=== wrong, should be ps1
					 * Without check #2, "cmd & <newline>"
					 * is similarly mistreated.
					 * (BTW, this makes "cmd & cmd"
					 * and "cmd && cmd" non-orthogonal.
					 * Really, ask yourself, why
					 * "cmd && <newline>" doesn't start
					 * cmd but waits for more input?
					 * The only reason is that it might be
					 * a "cmd1 && <nl> cmd2 &" construct,
					 * cmd1 may need to run in BG).
					 */
					struct pipe *pi = ctx.list_head;
					if (pi->num_cmds != 0       /* check #1 */
					 && pi->followup != PIPE_BG /* check #2 */
					) {
						continue;
					}
				}
				/* Treat newline as a command separator. */
				done_pipe(&ctx, PIPE_SEQ);
				debug_printf_parse("heredoc_cnt:%d\n", heredoc_cnt);
				if (heredoc_cnt) {
					if (fetch_heredocs(heredoc_cnt, &ctx, input)) {
						goto parse_error;
					}
					heredoc_cnt = 0;
				}
				dest.o_assignment = MAYBE_ASSIGNMENT;
				debug_printf_parse("dest.o_assignment='%s'\n", assignment_flag[dest.o_assignment]);
				ch = ';';
				/* note: if (is_blank) continue;
				 * will still trigger for us */
			}
		}

		/* "cmd}" or "cmd }..." without semicolon or &:
		 * } is an ordinary char in this case, even inside { cmd; }
		 * Pathological example: { ""}; } should exec "}" cmd
		 */
		if (ch == '}') {
			if (dest.length != 0 /* word} */
			 || dest.has_quoted_part    /* ""} */
			) {
				goto ordinary_char;
			}
			if (!IS_NULL_CMD(ctx.command)) { /* cmd } */
				/* Generally, there should be semicolon: "cmd; }"
				 * However, bash allows to omit it if "cmd" is
				 * a group. Examples:
				 * { { echo 1; } }
				 * {(echo 1)}
				 * { echo 0 >&2 | { echo 1; } }
				 * { while false; do :; done }
				 * { case a in b) ;; esac }
				 */
				if (ctx.command->group)
					goto term_group;
				goto ordinary_char;
			}
			if (!IS_NULL_PIPE(ctx.pipe)) /* cmd | } */
				/* Can't be an end of {cmd}, skip the check */
				goto skip_end_trigger;
			/* else: } does terminate a group */
		}
 term_group:
		if (end_trigger && end_trigger == ch
		 && (ch != ';' || heredoc_cnt == 0)
#if ENABLE_HUSH_CASE
		 && (ch != ')'
		    || ctx.ctx_res_w != RES_MATCH
		    || (!dest.has_quoted_part && strcmp(dest.data, "esac") == 0)
		    )
#endif
		) {
			if (heredoc_cnt) {
				/* This is technically valid:
				 * { cat <<HERE; }; echo Ok
				 * heredoc
				 * heredoc
				 * HERE
				 * but we don't support this.
				 * We require heredoc to be in enclosing {}/(),
				 * if any.
				 */
				syntax_error_unterm_str("here document");
				goto parse_error;
			}
			if (done_word(&dest, &ctx)) {
				goto parse_error;
			}
			done_pipe(&ctx, PIPE_SEQ);
			dest.o_assignment = MAYBE_ASSIGNMENT;
			debug_printf_parse("dest.o_assignment='%s'\n", assignment_flag[dest.o_assignment]);
			/* Do we sit outside of any if's, loops or case's? */
			if (!HAS_KEYWORDS
			IF_HAS_KEYWORDS(|| (ctx.ctx_res_w == RES_NONE && ctx.old_flag == 0))
			) {
				o_free(&dest);
#if !BB_MMU
				debug_printf_parse("as_string2 '%s'\n", ctx.as_string.data);
				if (pstring)
					*pstring = ctx.as_string.data;
				else
					o_free_unsafe(&ctx.as_string);
#endif
				if (ch != ';' && IS_NULL_PIPE(ctx.list_head)) {
					/* Example: bare "{ }", "()" */
					G.last_exitcode = 2; /* bash compat */
					syntax_error_unexpected_ch(ch);
					goto parse_error2;
				}
				debug_printf_parse("parse_stream return %p: "
						"end_trigger char found\n",
						ctx.list_head);
				debug_leave();
				return ctx.list_head;
			}
		}
 skip_end_trigger:
		if (is_blank)
			continue;

		/* Catch <, > before deciding whether this word is
		 * an assignment. a=1 2>z b=2: b=2 is still assignment */
		switch (ch) {
		case '>':
			redir_fd = redirect_opt_num(&dest);
			if (done_word(&dest, &ctx)) {
				goto parse_error;
			}
			redir_style = REDIRECT_OVERWRITE;
			if (next == '>') {
				redir_style = REDIRECT_APPEND;
				ch = i_getch(input);
				nommu_addchr(&ctx.as_string, ch);
			}
#if 0
			else if (next == '(') {
				syntax_error(">(process) not supported");
				goto parse_error;
			}
#endif
			if (parse_redirect(&ctx, redir_fd, redir_style, input))
				goto parse_error;
			continue; /* back to top of while (1) */
		case '<':
			redir_fd = redirect_opt_num(&dest);
			if (done_word(&dest, &ctx)) {
				goto parse_error;
			}
			redir_style = REDIRECT_INPUT;
			if (next == '<') {
				redir_style = REDIRECT_HEREDOC;
				heredoc_cnt++;
				debug_printf_parse("++heredoc_cnt=%d\n", heredoc_cnt);
				ch = i_getch(input);
				nommu_addchr(&ctx.as_string, ch);
			} else if (next == '>') {
				redir_style = REDIRECT_IO;
				ch = i_getch(input);
				nommu_addchr(&ctx.as_string, ch);
			}
#if 0
			else if (next == '(') {
				syntax_error("<(process) not supported");
				goto parse_error;
			}
#endif
			if (parse_redirect(&ctx, redir_fd, redir_style, input))
				goto parse_error;
			continue; /* back to top of while (1) */
		case '#':
			if (dest.length == 0 && !dest.has_quoted_part) {
				/* skip "#comment" */
				while (1) {
					ch = i_peek(input);
					if (ch == EOF || ch == '\n')
						break;
					i_getch(input);
					/* note: we do not add it to &ctx.as_string */
				}
				nommu_addchr(&ctx.as_string, '\n');
				continue; /* back to top of while (1) */
			}
			break;
		case '\\':
			if (next == '\n') {
				/* It's "\<newline>" */
#if !BB_MMU
				/* Remove trailing '\' from ctx.as_string */
				ctx.as_string.data[--ctx.as_string.length] = '\0';
#endif
				ch = i_getch(input); /* eat it */
				continue; /* back to top of while (1) */
			}
			break;
		}

		if (dest.o_assignment == MAYBE_ASSIGNMENT
		 /* check that we are not in word in "a=1 2>word b=1": */
		 && !ctx.pending_redirect
		) {
			/* ch is a special char and thus this word
			 * cannot be an assignment */
			dest.o_assignment = NOT_ASSIGNMENT;
			debug_printf_parse("dest.o_assignment='%s'\n", assignment_flag[dest.o_assignment]);
		}

		/* Note: nommu_addchr(&ctx.as_string, ch) is already done */

		switch (ch) {
		case '#': /* non-comment #: "echo a#b" etc */
			o_addQchr(&dest, ch);
			break;
		case '\\':
			if (next == EOF) {
				syntax_error("\\<eof>");
				xfunc_die();
			}
			ch = i_getch(input);
			/* note: ch != '\n' (that case does not reach this place) */
			o_addchr(&dest, '\\');
			/*nommu_addchr(&ctx.as_string, '\\'); - already done */
			o_addchr(&dest, ch);
			nommu_addchr(&ctx.as_string, ch);
			/* Example: echo Hello \2>file
			 * we need to know that word 2 is quoted */
			dest.has_quoted_part = 1;
			break;
		case '$':
			if (!parse_dollar(&ctx.as_string, &dest, input, /*quote_mask:*/ 0)) {
				debug_printf_parse("parse_stream parse error: "
					"parse_dollar returned 0 (error)\n");
				goto parse_error;
			}
			break;
		case '\'':
			dest.has_quoted_part = 1;
			if (next == '\'' && !ctx.pending_redirect) {
 insert_empty_quoted_str_marker:
				nommu_addchr(&ctx.as_string, next);
				i_getch(input); /* eat second ' */
				o_addchr(&dest, SPECIAL_VAR_SYMBOL);
				o_addchr(&dest, SPECIAL_VAR_SYMBOL);
			} else {
				while (1) {
					ch = i_getch(input);
					if (ch == EOF) {
						syntax_error_unterm_ch('\'');
						goto parse_error;
					}
					nommu_addchr(&ctx.as_string, ch);
					if (ch == '\'')
						break;
					o_addqchr(&dest, ch);
				}
			}
			break;
		case '"':
			dest.has_quoted_part = 1;
			if (next == '"' && !ctx.pending_redirect)
				goto insert_empty_quoted_str_marker;
			if (dest.o_assignment == NOT_ASSIGNMENT)
				dest.o_expflags |= EXP_FLAG_ESC_GLOB_CHARS;
			if (!encode_string(&ctx.as_string, &dest, input, '"', /*process_bkslash:*/ 1))
				goto parse_error;
			dest.o_expflags &= ~EXP_FLAG_ESC_GLOB_CHARS;
			break;
#if ENABLE_HUSH_TICK
		case '`': {
			USE_FOR_NOMMU(unsigned pos;)

			o_addchr(&dest, SPECIAL_VAR_SYMBOL);
			o_addchr(&dest, '`');
			USE_FOR_NOMMU(pos = dest.length;)
			if (!add_till_backquote(&dest, input, /*in_dquote:*/ 0))
				goto parse_error;
# if !BB_MMU
			o_addstr(&ctx.as_string, dest.data + pos);
			o_addchr(&ctx.as_string, '`');
# endif
			o_addchr(&dest, SPECIAL_VAR_SYMBOL);
			//debug_printf_subst("SUBST RES3 '%s'\n", dest.data + pos);
			break;
		}
#endif
		case ';':
#if ENABLE_HUSH_CASE
 case_semi:
#endif
			if (done_word(&dest, &ctx)) {
				goto parse_error;
			}
			done_pipe(&ctx, PIPE_SEQ);
#if ENABLE_HUSH_CASE
			/* Eat multiple semicolons, detect
			 * whether it means something special */
			while (1) {
				ch = i_peek(input);
				if (ch != ';')
					break;
				ch = i_getch(input);
				nommu_addchr(&ctx.as_string, ch);
				if (ctx.ctx_res_w == RES_CASE_BODY) {
					ctx.ctx_dsemicolon = 1;
					ctx.ctx_res_w = RES_MATCH;
					break;
				}
			}
#endif
 new_cmd:
			/* We just finished a cmd. New one may start
			 * with an assignment */
			dest.o_assignment = MAYBE_ASSIGNMENT;
			debug_printf_parse("dest.o_assignment='%s'\n", assignment_flag[dest.o_assignment]);
			break;
		case '&':
			if (done_word(&dest, &ctx)) {
				goto parse_error;
			}
			if (next == '&') {
				ch = i_getch(input);
				nommu_addchr(&ctx.as_string, ch);
				done_pipe(&ctx, PIPE_AND);
			} else {
				done_pipe(&ctx, PIPE_BG);
			}
			goto new_cmd;
		case '|':
			if (done_word(&dest, &ctx)) {
				goto parse_error;
			}
#if ENABLE_HUSH_CASE
			if (ctx.ctx_res_w == RES_MATCH)
				break; /* we are in case's "word | word)" */
#endif
			if (next == '|') { /* || */
				ch = i_getch(input);
				nommu_addchr(&ctx.as_string, ch);
				done_pipe(&ctx, PIPE_OR);
			} else {
				/* we could pick up a file descriptor choice here
				 * with redirect_opt_num(), but bash doesn't do it.
				 * "echo foo 2| cat" yields "foo 2". */
				done_command(&ctx);
			}
			goto new_cmd;
		case '(':
#if ENABLE_HUSH_CASE
			/* "case... in [(]word)..." - skip '(' */
			if (ctx.ctx_res_w == RES_MATCH
			 && ctx.command->argv == NULL /* not (word|(... */
			 && dest.length == 0 /* not word(... */
			 && dest.has_quoted_part == 0 /* not ""(... */
			) {
				continue;
			}
#endif
		case '{':
			if (parse_group(&dest, &ctx, input, ch) != 0) {
				goto parse_error;
			}
			goto new_cmd;
		case ')':
#if ENABLE_HUSH_CASE
			if (ctx.ctx_res_w == RES_MATCH)
				goto case_semi;
#endif
		case '}':
			/* proper use of this character is caught by end_trigger:
			 * if we see {, we call parse_group(..., end_trigger='}')
			 * and it will match } earlier (not here). */
			G.last_exitcode = 2;
			syntax_error_unexpected_ch(ch);
			goto parse_error2;
		default:
			if (HUSH_DEBUG)
				bb_error_msg_and_die("BUG: unexpected %c\n", ch);
		}
	} /* while (1) */

 parse_error:
	G.last_exitcode = 1;
 parse_error2:
	{
		struct parse_context *pctx;
		IF_HAS_KEYWORDS(struct parse_context *p2;)

		/* Clean up allocated tree.
		 * Sample for finding leaks on syntax error recovery path.
		 * Run it from interactive shell, watch pmap `pidof hush`.
		 * while if false; then false; fi; do break; fi
		 * Samples to catch leaks at execution:
		 * while if (true | { true;}); then echo ok; fi; do break; done
		 * while if (true | { true;}); then echo ok; fi; do (if echo ok; break; then :; fi) | cat; break; done
		 */
		pctx = &ctx;
		do {
			/* Update pipe/command counts,
			 * otherwise freeing may miss some */
			done_pipe(pctx, PIPE_SEQ);
			debug_printf_clean("freeing list %p from ctx %p\n",
					pctx->list_head, pctx);
			debug_print_tree(pctx->list_head, 0);
			free_pipe_list(pctx->list_head);
			debug_printf_clean("freed list %p\n", pctx->list_head);
#if !BB_MMU
			o_free_unsafe(&pctx->as_string);
#endif
			IF_HAS_KEYWORDS(p2 = pctx->stack;)
			if (pctx != &ctx) {
				free(pctx);
			}
			IF_HAS_KEYWORDS(pctx = p2;)
		} while (HAS_KEYWORDS && pctx);

		o_free(&dest);
#if !BB_MMU
		if (pstring)
			*pstring = NULL;
#endif
		debug_leave();
		return ERR_PTR;
	}
}


/*** Execution routines ***/

/* Expansion can recurse, need forward decls: */
#if !BASH_PATTERN_SUBST && !ENABLE_HUSH_CASE
/* only ${var/pattern/repl} (its pattern part) needs additional mode */
#define expand_string_to_string(str, do_unbackslash) \
	expand_string_to_string(str)
#endif
static char *expand_string_to_string(const char *str, int do_unbackslash);
#if ENABLE_HUSH_TICK
static int process_command_subs(o_string *dest, const char *s);
#endif

/* expand_strvec_to_strvec() takes a list of strings, expands
 * all variable references within and returns a pointer to
 * a list of expanded strings, possibly with larger number
 * of strings. (Think VAR="a b"; echo $VAR).
 * This new list is allocated as a single malloc block.
 * NULL-terminated list of char* pointers is at the beginning of it,
 * followed by strings themselves.
 * Caller can deallocate entire list by single free(list). */

/* A horde of its helpers come first: */

static void o_addblock_duplicate_backslash(o_string *o, const char *str, int len)
{
	while (--len >= 0) {
		char c = *str++;

#if ENABLE_HUSH_BRACE_EXPANSION
		if (c == '{' || c == '}') {
			/* { -> \{, } -> \} */
			o_addchr(o, '\\');
			/* And now we want to add { or } and continue:
			 *  o_addchr(o, c);
			 *  continue;
			 * luckily, just falling through achieves this.
			 */
		}
#endif
		o_addchr(o, c);
		if (c == '\\') {
			/* \z -> \\\z; \<eol> -> \\<eol> */
			o_addchr(o, '\\');
			if (len) {
				len--;
				o_addchr(o, '\\');
				o_addchr(o, *str++);
			}
		}
	}
}

/* Store given string, finalizing the word and starting new one whenever
 * we encounter IFS char(s). This is used for expanding variable values.
 * End-of-string does NOT finalize word: think about 'echo -$VAR-'.
 * Return in *ended_with_ifs:
 * 1 - ended with IFS char, else 0 (this includes case of empty str).
 */
static int expand_on_ifs(int *ended_with_ifs, o_string *output, int n, const char *str)
{
	int last_is_ifs = 0;

	while (1) {
		int word_len;

		if (!*str)  /* EOL - do not finalize word */
			break;
		word_len = strcspn(str, G.ifs);
		if (word_len) {
			/* We have WORD_LEN leading non-IFS chars */
			if (!(output->o_expflags & EXP_FLAG_GLOB)) {
				o_addblock(output, str, word_len);
			} else {
				/* Protect backslashes against globbing up :)
				 * Example: "v='\*'; echo b$v" prints "b\*"
				 * (and does not try to glob on "*")
				 */
				o_addblock_duplicate_backslash(output, str, word_len);
				/*/ Why can't we do it easier? */
				/*o_addblock(output, str, word_len); - WRONG: "v='\*'; echo Z$v" prints "Z*" instead of "Z\*" */
				/*o_addqblock(output, str, word_len); - WRONG: "v='*'; echo Z$v" prints "Z*" instead of Z* files */
			}
			last_is_ifs = 0;
			str += word_len;
			if (!*str)  /* EOL - do not finalize word */
				break;
		}

		/* We know str here points to at least one IFS char */
		last_is_ifs = 1;
		str += strspn(str, G.ifs); /* skip IFS chars */
		if (!*str)  /* EOL - do not finalize word */
			break;

		/* Start new word... but not always! */
		/* Case "v=' a'; echo ''$v": we do need to finalize empty word: */
		if (output->has_quoted_part
		/* Case "v=' a'; echo $v":
		 * here nothing precedes the space in $v expansion,
		 * therefore we should not finish the word
		 * (IOW: if there *is* word to finalize, only then do it):
		 */
		 || (n > 0 && output->data[output->length - 1])
		) {
			o_addchr(output, '\0');
			debug_print_list("expand_on_ifs", output, n);
			n = o_save_ptr(output, n);
		}
	}

	if (ended_with_ifs)
		*ended_with_ifs = last_is_ifs;
	debug_print_list("expand_on_ifs[1]", output, n);
	return n;
}

/* Helper to expand $((...)) and heredoc body. These act as if
 * they are in double quotes, with the exception that they are not :).
 * Just the rules are similar: "expand only $var and `cmd`"
 *
 * Returns malloced string.
 * As an optimization, we return NULL if expansion is not needed.
 */
#if !BASH_PATTERN_SUBST
/* only ${var/pattern/repl} (its pattern part) needs additional mode */
#define encode_then_expand_string(str, process_bkslash, do_unbackslash) \
	encode_then_expand_string(str)
#endif
static char *encode_then_expand_string(const char *str, int process_bkslash, int do_unbackslash)
{
#if !BASH_PATTERN_SUBST
	const int do_unbackslash = 1;
#endif
	char *exp_str;
	struct in_str input;
	o_string dest = NULL_O_STRING;

	if (!strchr(str, '$')
	 && !strchr(str, '\\')
#if ENABLE_HUSH_TICK
	 && !strchr(str, '`')
#endif
	) {
		return NULL;
	}

	/* We need to expand. Example:
	 * echo $(($a + `echo 1`)) $((1 + $((2)) ))
	 */
	setup_string_in_str(&input, str);
	encode_string(NULL, &dest, &input, EOF, process_bkslash);
//TODO: error check (encode_string returns 0 on error)?
	//bb_error_msg("'%s' -> '%s'", str, dest.data);
	exp_str = expand_string_to_string(dest.data, /*unbackslash:*/ do_unbackslash);
	//bb_error_msg("'%s' -> '%s'", dest.data, exp_str);
	o_free_unsafe(&dest);
	return exp_str;
}

#if ENABLE_FEATURE_SH_MATH
static arith_t expand_and_evaluate_arith(const char *arg, const char **errmsg_p)
{
	arith_state_t math_state;
	arith_t res;
	char *exp_str;

	math_state.lookupvar = get_local_var_value;
	math_state.setvar = set_local_var_from_halves;
	//math_state.endofname = endofname;
	exp_str = encode_then_expand_string(arg, /*process_bkslash:*/ 1, /*unbackslash:*/ 1);
	res = arith(&math_state, exp_str ? exp_str : arg);
	free(exp_str);
	if (errmsg_p)
		*errmsg_p = math_state.errmsg;
	if (math_state.errmsg)
		msg_and_die_if_script(math_state.errmsg);
	return res;
}
#endif

#if BASH_PATTERN_SUBST
/* ${var/[/]pattern[/repl]} helpers */
static char *strstr_pattern(char *val, const char *pattern, int *size)
{
	while (1) {
		char *end = scan_and_match(val, pattern, SCAN_MOVE_FROM_RIGHT + SCAN_MATCH_LEFT_HALF);
		debug_printf_varexp("val:'%s' pattern:'%s' end:'%s'\n", val, pattern, end);
		if (end) {
			*size = end - val;
			return val;
		}
		if (*val == '\0')
			return NULL;
		/* Optimization: if "*pat" did not match the start of "string",
		 * we know that "tring", "ring" etc will not match too:
		 */
		if (pattern[0] == '*')
			return NULL;
		val++;
	}
}
static char *replace_pattern(char *val, const char *pattern, const char *repl, char exp_op)
{
	char *result = NULL;
	unsigned res_len = 0;
	unsigned repl_len = strlen(repl);

	while (1) {
		int size;
		char *s = strstr_pattern(val, pattern, &size);
		if (!s)
			break;

		result = xrealloc(result, res_len + (s - val) + repl_len + 1);
		strcpy(mempcpy(result + res_len, val, s - val), repl);
		res_len += (s - val) + repl_len;
		debug_printf_varexp("val:'%s' s:'%s' result:'%s'\n", val, s, result);

		val = s + size;
		if (exp_op == '/')
			break;
	}
	if (*val && result) {
		result = xrealloc(result, res_len + strlen(val) + 1);
		strcpy(result + res_len, val);
		debug_printf_varexp("val:'%s' result:'%s'\n", val, result);
	}
	debug_printf_varexp("result:'%s'\n", result);
	return result;
}
#endif /* BASH_PATTERN_SUBST */

/* Helper:
 * Handles <SPECIAL_VAR_SYMBOL>varname...<SPECIAL_VAR_SYMBOL> construct.
 */
static NOINLINE const char *expand_one_var(char **to_be_freed_pp, char *arg, char **pp)
{
	const char *val = NULL;
	char *to_be_freed = NULL;
	char *p = *pp;
	char *var;
	char first_char;
	char exp_op;
	char exp_save = exp_save; /* for compiler */
	char *exp_saveptr; /* points to expansion operator */
	char *exp_word = exp_word; /* for compiler */
	char arg0;

	*p = '\0'; /* replace trailing SPECIAL_VAR_SYMBOL */
	var = arg;
	exp_saveptr = arg[1] ? strchr(VAR_ENCODED_SUBST_OPS, arg[1]) : NULL;
	arg0 = arg[0];
	first_char = arg[0] = arg0 & 0x7f;
	exp_op = 0;

	if (first_char == '#' && arg[1] /* ${#...} but not ${#} */
	 && (!exp_saveptr               /* and ( not(${#<op_char>...}) */
	    || (arg[2] == '\0' && strchr(SPECIAL_VARS_STR, arg[1])) /* or ${#C} "len of $C" ) */
	    )		/* NB: skipping ^^^specvar check mishandles ${#::2} */
	) {
		/* It must be length operator: ${#var} */
		var++;
		exp_op = 'L';
	} else {
		/* Maybe handle parameter expansion */
		if (exp_saveptr /* if 2nd char is one of expansion operators */
		 && strchr(NUMERIC_SPECVARS_STR, first_char) /* 1st char is special variable */
		) {
			/* ${?:0}, ${#[:]%0} etc */
			exp_saveptr = var + 1;
		} else {
			/* ${?}, ${var}, ${var:0}, ${var[:]%0} etc */
			exp_saveptr = var+1 + strcspn(var+1, VAR_ENCODED_SUBST_OPS);
		}
		exp_op = exp_save = *exp_saveptr;
		if (exp_op) {
			exp_word = exp_saveptr + 1;
			if (exp_op == ':') {
				exp_op = *exp_word++;
//TODO: try ${var:} and ${var:bogus} in non-bash config
				if (BASH_SUBSTR
				 && (!exp_op || !strchr(MINUS_PLUS_EQUAL_QUESTION, exp_op))
				) {
					/* oops... it's ${var:N[:M]}, not ${var:?xxx} or some such */
					exp_op = ':';
					exp_word--;
				}
			}
			*exp_saveptr = '\0';
		} /* else: it's not an expansion op, but bare ${var} */
	}

	/* Look up the variable in question */
	if (isdigit(var[0])) {
		/* parse_dollar should have vetted var for us */
		int n = xatoi_positive(var);
		if (n < G.global_argc)
			val = G.global_argv[n];
		/* else val remains NULL: $N with too big N */
	} else {
		switch (var[0]) {
		case '$': /* pid */
			val = utoa(G.root_pid);
			break;
		case '!': /* bg pid */
			val = G.last_bg_pid ? utoa(G.last_bg_pid) : "";
			break;
		case '?': /* exitcode */
			val = utoa(G.last_exitcode);
			break;
		case '#': /* argc */
			val = utoa(G.global_argc ? G.global_argc-1 : 0);
			break;
		default:
			val = get_local_var_value(var);
		}
	}

	/* Handle any expansions */
	if (exp_op == 'L') {
		reinit_unicode_for_hush();
		debug_printf_expand("expand: length(%s)=", val);
		val = utoa(val ? unicode_strlen(val) : 0);
		debug_printf_expand("%s\n", val);
	} else if (exp_op) {
		if (exp_op == '%' || exp_op == '#') {
			/* Standard-mandated substring removal ops:
			 * ${parameter%word} - remove smallest suffix pattern
			 * ${parameter%%word} - remove largest suffix pattern
			 * ${parameter#word} - remove smallest prefix pattern
			 * ${parameter##word} - remove largest prefix pattern
			 *
			 * Word is expanded to produce a glob pattern.
			 * Then var's value is matched to it and matching part removed.
			 */
			if (val && val[0]) {
				char *t;
				char *exp_exp_word;
				char *loc;
				unsigned scan_flags = pick_scan(exp_op, *exp_word);
				if (exp_op == *exp_word)  /* ## or %% */
					exp_word++;
				exp_exp_word = encode_then_expand_string(exp_word, /*process_bkslash:*/ 1, /*unbackslash:*/ 1);
				if (exp_exp_word)
					exp_word = exp_exp_word;
				/* HACK ALERT. We depend here on the fact that
				 * G.global_argv and results of utoa and get_local_var_value
				 * are actually in writable memory:
				 * scan_and_match momentarily stores NULs there. */
				t = (char*)val;
				loc = scan_and_match(t, exp_word, scan_flags);
				//bb_error_msg("op:%c str:'%s' pat:'%s' res:'%s'",
				//		exp_op, t, exp_word, loc);
				free(exp_exp_word);
				if (loc) { /* match was found */
					if (scan_flags & SCAN_MATCH_LEFT_HALF) /* #[#] */
						val = loc; /* take right part */
					else /* %[%] */
						val = to_be_freed = xstrndup(val, loc - val); /* left */
				}
			}
		}
#if BASH_PATTERN_SUBST
		else if (exp_op == '/' || exp_op == '\\') {
			/* It's ${var/[/]pattern[/repl]} thing.
			 * Note that in encoded form it has TWO parts:
			 * var/pattern<SPECIAL_VAR_SYMBOL>repl<SPECIAL_VAR_SYMBOL>
			 * and if // is used, it is encoded as \:
			 * var\pattern<SPECIAL_VAR_SYMBOL>repl<SPECIAL_VAR_SYMBOL>
			 */
			/* Empty variable always gives nothing: */
			// "v=''; echo ${v/*/w}" prints "", not "w"
			if (val && val[0]) {
				/* pattern uses non-standard expansion.
				 * repl should be unbackslashed and globbed
				 * by the usual expansion rules:
				 * >az; >bz;
				 * v='a bz'; echo "${v/a*z/a*z}" prints "a*z"
				 * v='a bz'; echo "${v/a*z/\z}"  prints "\z"
				 * v='a bz'; echo ${v/a*z/a*z}   prints "az"
				 * v='a bz'; echo ${v/a*z/\z}    prints "z"
				 * (note that a*z _pattern_ is never globbed!)
				 */
				char *pattern, *repl, *t;
				pattern = encode_then_expand_string(exp_word, /*process_bkslash:*/ 0, /*unbackslash:*/ 0);
				if (!pattern)
					pattern = xstrdup(exp_word);
				debug_printf_varexp("pattern:'%s'->'%s'\n", exp_word, pattern);
				*p++ = SPECIAL_VAR_SYMBOL;
				exp_word = p;
				p = strchr(p, SPECIAL_VAR_SYMBOL);
				*p = '\0';
				repl = encode_then_expand_string(exp_word, /*process_bkslash:*/ arg0 & 0x80, /*unbackslash:*/ 1);
				debug_printf_varexp("repl:'%s'->'%s'\n", exp_word, repl);
				/* HACK ALERT. We depend here on the fact that
				 * G.global_argv and results of utoa and get_local_var_value
				 * are actually in writable memory:
				 * replace_pattern momentarily stores NULs there. */
				t = (char*)val;
				to_be_freed = replace_pattern(t,
						pattern,
						(repl ? repl : exp_word),
						exp_op);
				if (to_be_freed) /* at least one replace happened */
					val = to_be_freed;
				free(pattern);
				free(repl);
			}
		}
#endif /* BASH_PATTERN_SUBST */
		else if (exp_op == ':') {
#if BASH_SUBSTR && ENABLE_FEATURE_SH_MATH
			/* It's ${var:N[:M]} bashism.
			 * Note that in encoded form it has TWO parts:
			 * var:N<SPECIAL_VAR_SYMBOL>M<SPECIAL_VAR_SYMBOL>
			 */
			arith_t beg, len;
			const char *errmsg;

			beg = expand_and_evaluate_arith(exp_word, &errmsg);
			if (errmsg)
				goto arith_err;
			debug_printf_varexp("beg:'%s'=%lld\n", exp_word, (long long)beg);
			*p++ = SPECIAL_VAR_SYMBOL;
			exp_word = p;
			p = strchr(p, SPECIAL_VAR_SYMBOL);
			*p = '\0';
			len = expand_and_evaluate_arith(exp_word, &errmsg);
			if (errmsg)
				goto arith_err;
			debug_printf_varexp("len:'%s'=%lld\n", exp_word, (long long)len);
			if (beg < 0) {
				/* negative beg counts from the end */
				beg = (arith_t)strlen(val) + beg;
				if (beg < 0) /* ${v: -999999} is "" */
					beg = len = 0;
			}
			debug_printf_varexp("from val:'%s'\n", val);
			if (len < 0) {
				/* in bash, len=-n means strlen()-n */
				len = (arith_t)strlen(val) - beg + len;
				if (len < 0) /* bash compat */
					msg_and_die_if_script("%s: substring expression < 0", var);
			}
			if (len <= 0 || !val || beg >= strlen(val)) {
 arith_err:
				val = NULL;
			} else {
				/* Paranoia. What if user entered 9999999999999
				 * which fits in arith_t but not int? */
				if (len >= INT_MAX)
					len = INT_MAX;
				val = to_be_freed = xstrndup(val + beg, len);
			}
			debug_printf_varexp("val:'%s'\n", val);
#else /* not (HUSH_SUBSTR_EXPANSION && FEATURE_SH_MATH) */
			msg_and_die_if_script("malformed ${%s:...}", var);
			val = NULL;
#endif
		} else { /* one of "-=+?" */
			/* Standard-mandated substitution ops:
			 * ${var?word} - indicate error if unset
			 *      If var is unset, word (or a message indicating it is unset
			 *      if word is null) is written to standard error
			 *      and the shell exits with a non-zero exit status.
			 *      Otherwise, the value of var is substituted.
			 * ${var-word} - use default value
			 *      If var is unset, word is substituted.
			 * ${var=word} - assign and use default value
			 *      If var is unset, word is assigned to var.
			 *      In all cases, final value of var is substituted.
			 * ${var+word} - use alternative value
			 *      If var is unset, null is substituted.
			 *      Otherwise, word is substituted.
			 *
			 * Word is subjected to tilde expansion, parameter expansion,
			 * command substitution, and arithmetic expansion.
			 * If word is not needed, it is not expanded.
			 *
			 * Colon forms (${var:-word}, ${var:=word} etc) do the same,
			 * but also treat null var as if it is unset.
			 */
			int use_word = (!val || ((exp_save == ':') && !val[0]));
			if (exp_op == '+')
				use_word = !use_word;
			debug_printf_expand("expand: op:%c (null:%s) test:%i\n", exp_op,
					(exp_save == ':') ? "true" : "false", use_word);
			if (use_word) {
				to_be_freed = encode_then_expand_string(exp_word, /*process_bkslash:*/ 1, /*unbackslash:*/ 1);
				if (to_be_freed)
					exp_word = to_be_freed;
				if (exp_op == '?') {
					/* mimic bash message */
					msg_and_die_if_script("%s: %s",
						var,
						exp_word[0]
						? exp_word
						: "parameter null or not set"
						/* ash has more specific messages, a-la: */
						/*: (exp_save == ':' ? "parameter null or not set" : "parameter not set")*/
					);
//TODO: how interactive bash aborts expansion mid-command?
				} else {
					val = exp_word;
				}

				if (exp_op == '=') {
					/* ${var=[word]} or ${var:=[word]} */
					if (isdigit(var[0]) || var[0] == '#') {
						/* mimic bash message */
						msg_and_die_if_script("$%s: cannot assign in this way", var);
						val = NULL;
					} else {
						char *new_var = xasprintf("%s=%s", var, val);
						set_local_var(new_var, /*flag:*/ 0);
					}
				}
			}
		} /* one of "-=+?" */

		*exp_saveptr = exp_save;
	} /* if (exp_op) */

	arg[0] = arg0;

	*pp = p;
	*to_be_freed_pp = to_be_freed;
	return val;
}

/* Expand all variable references in given string, adding words to list[]
 * at n, n+1,... positions. Return updated n (so that list[n] is next one
 * to be filled). This routine is extremely tricky: has to deal with
 * variables/parameters with whitespace, $* and $@, and constructs like
 * 'echo -$*-'. If you play here, you must run testsuite afterwards! */
static NOINLINE int expand_vars_to_list(o_string *output, int n, char *arg)
{
	/* output->o_expflags & EXP_FLAG_SINGLEWORD (0x80) if we are in
	 * expansion of right-hand side of assignment == 1-element expand.
	 */
	char cant_be_null = 0; /* only bit 0x80 matters */
	int ended_in_ifs = 0;  /* did last unquoted expansion end with IFS chars? */
	char *p;

	debug_printf_expand("expand_vars_to_list: arg:'%s' singleword:%x\n", arg,
			!!(output->o_expflags & EXP_FLAG_SINGLEWORD));
	debug_print_list("expand_vars_to_list", output, n);
	n = o_save_ptr(output, n);
	debug_print_list("expand_vars_to_list[0]", output, n);

	while ((p = strchr(arg, SPECIAL_VAR_SYMBOL)) != NULL) {
		char first_ch;
		char *to_be_freed = NULL;
		const char *val = NULL;
#if ENABLE_HUSH_TICK
		o_string subst_result = NULL_O_STRING;
#endif
#if ENABLE_FEATURE_SH_MATH
		char arith_buf[sizeof(arith_t)*3 + 2];
#endif

		if (ended_in_ifs) {
			o_addchr(output, '\0');
			n = o_save_ptr(output, n);
			ended_in_ifs = 0;
		}

		o_addblock(output, arg, p - arg);
		debug_print_list("expand_vars_to_list[1]", output, n);
		arg = ++p;
		p = strchr(p, SPECIAL_VAR_SYMBOL);

		/* Fetch special var name (if it is indeed one of them)
		 * and quote bit, force the bit on if singleword expansion -
		 * important for not getting v=$@ expand to many words. */
		first_ch = arg[0] | (output->o_expflags & EXP_FLAG_SINGLEWORD);

		/* Is this variable quoted and thus expansion can't be null?
		 * "$@" is special. Even if quoted, it can still
		 * expand to nothing (not even an empty string),
		 * thus it is excluded. */
		if ((first_ch & 0x7f) != '@')
			cant_be_null |= first_ch;

		switch (first_ch & 0x7f) {
		/* Highest bit in first_ch indicates that var is double-quoted */
		case '*':
		case '@': {
			int i;
			if (!G.global_argv[1])
				break;
			i = 1;
			cant_be_null |= first_ch; /* do it for "$@" _now_, when we know it's not empty */
			if (!(first_ch & 0x80)) { /* unquoted $* or $@ */
				while (G.global_argv[i]) {
					n = expand_on_ifs(NULL, output, n, G.global_argv[i]);
					debug_printf_expand("expand_vars_to_list: argv %d (last %d)\n", i, G.global_argc - 1);
					if (G.global_argv[i++][0] && G.global_argv[i]) {
						/* this argv[] is not empty and not last:
						 * put terminating NUL, start new word */
						o_addchr(output, '\0');
						debug_print_list("expand_vars_to_list[2]", output, n);
						n = o_save_ptr(output, n);
						debug_print_list("expand_vars_to_list[3]", output, n);
					}
				}
			} else
			/* If EXP_FLAG_SINGLEWORD, we handle assignment 'a=....$@.....'
			 * and in this case should treat it like '$*' - see 'else...' below */
			if (first_ch == ('@'|0x80)  /* quoted $@ */
			 && !(output->o_expflags & EXP_FLAG_SINGLEWORD) /* not v="$@" case */
			) {
				while (1) {
					o_addQstr(output, G.global_argv[i]);
					if (++i >= G.global_argc)
						break;
					o_addchr(output, '\0');
					debug_print_list("expand_vars_to_list[4]", output, n);
					n = o_save_ptr(output, n);
				}
			} else { /* quoted $* (or v="$@" case): add as one word */
				while (1) {
					o_addQstr(output, G.global_argv[i]);
					if (!G.global_argv[++i])
						break;
					if (G.ifs[0])
						o_addchr(output, G.ifs[0]);
				}
				output->has_quoted_part = 1;
			}
			break;
		}
		case SPECIAL_VAR_SYMBOL: /* <SPECIAL_VAR_SYMBOL><SPECIAL_VAR_SYMBOL> */
			/* "Empty variable", used to make "" etc to not disappear */
			output->has_quoted_part = 1;
			arg++;
			cant_be_null = 0x80;
			break;
#if ENABLE_HUSH_TICK
		case '`': /* <SPECIAL_VAR_SYMBOL>`cmd<SPECIAL_VAR_SYMBOL> */
			*p = '\0'; /* replace trailing <SPECIAL_VAR_SYMBOL> */
			arg++;
			/* Can't just stuff it into output o_string,
			 * expanded result may need to be globbed
			 * and $IFS-split */
			debug_printf_subst("SUBST '%s' first_ch %x\n", arg, first_ch);
			G.last_exitcode = process_command_subs(&subst_result, arg);
			debug_printf_subst("SUBST RES:%d '%s'\n", G.last_exitcode, subst_result.data);
			val = subst_result.data;
			goto store_val;
#endif
#if ENABLE_FEATURE_SH_MATH
		case '+': { /* <SPECIAL_VAR_SYMBOL>+cmd<SPECIAL_VAR_SYMBOL> */
			arith_t res;

			arg++; /* skip '+' */
			*p = '\0'; /* replace trailing <SPECIAL_VAR_SYMBOL> */
			debug_printf_subst("ARITH '%s' first_ch %x\n", arg, first_ch);
			res = expand_and_evaluate_arith(arg, NULL);
			debug_printf_subst("ARITH RES '"ARITH_FMT"'\n", res);
			sprintf(arith_buf, ARITH_FMT, res);
			val = arith_buf;
			break;
		}
#endif
		default:
			val = expand_one_var(&to_be_freed, arg, &p);
 IF_HUSH_TICK(store_val:)
			if (!(first_ch & 0x80)) { /* unquoted $VAR */
				debug_printf_expand("unquoted '%s', output->o_escape:%d\n", val,
						!!(output->o_expflags & EXP_FLAG_ESC_GLOB_CHARS));
				if (val && val[0]) {
					n = expand_on_ifs(&ended_in_ifs, output, n, val);
					val = NULL;
				}
			} else { /* quoted $VAR, val will be appended below */
				output->has_quoted_part = 1;
				debug_printf_expand("quoted '%s', output->o_escape:%d\n", val,
						!!(output->o_expflags & EXP_FLAG_ESC_GLOB_CHARS));
			}
			break;
		} /* switch (char after <SPECIAL_VAR_SYMBOL>) */

		if (val && val[0]) {
			o_addQstr(output, val);
		}
		free(to_be_freed);

		/* Restore NULL'ed SPECIAL_VAR_SYMBOL.
		 * Do the check to avoid writing to a const string. */
		if (*p != SPECIAL_VAR_SYMBOL)
			*p = SPECIAL_VAR_SYMBOL;

#if ENABLE_HUSH_TICK
		o_free(&subst_result);
#endif
		arg = ++p;
	} /* end of "while (SPECIAL_VAR_SYMBOL is found) ..." */

	if (arg[0]) {
		if (ended_in_ifs) {
			o_addchr(output, '\0');
			n = o_save_ptr(output, n);
		}
		debug_print_list("expand_vars_to_list[a]", output, n);
		/* this part is literal, and it was already pre-quoted
		 * if needed (much earlier), do not use o_addQstr here! */
		o_addstr_with_NUL(output, arg);
		debug_print_list("expand_vars_to_list[b]", output, n);
	} else if (output->length == o_get_last_ptr(output, n) /* expansion is empty */
	 && !(cant_be_null & 0x80) /* and all vars were not quoted. */
	) {
		n--;
		/* allow to reuse list[n] later without re-growth */
		output->has_empty_slot = 1;
	} else {
		o_addchr(output, '\0');
	}

	return n;
}

static char **expand_variables(char **argv, unsigned expflags)
{
	int n;
	char **list;
	o_string output = NULL_O_STRING;

	output.o_expflags = expflags;

	n = 0;
	while (*argv) {
		n = expand_vars_to_list(&output, n, *argv);
		argv++;
	}
	debug_print_list("expand_variables", &output, n);

	/* output.data (malloced in one block) gets returned in "list" */
	list = o_finalize_list(&output, n);
	debug_print_strings("expand_variables[1]", list);
	return list;
}

static char **expand_strvec_to_strvec(char **argv)
{
	return expand_variables(argv, EXP_FLAG_GLOB | EXP_FLAG_ESC_GLOB_CHARS);
}

#if BASH_TEST2
static char **expand_strvec_to_strvec_singleword_noglob(char **argv)
{
	return expand_variables(argv, EXP_FLAG_SINGLEWORD);
}
#endif

/* Used for expansion of right hand of assignments,
 * $((...)), heredocs, variable espansion parts.
 *
 * NB: should NOT do globbing!
 * "export v=/bin/c*; env | grep ^v=" outputs "v=/bin/c*"
 */
static char *expand_string_to_string(const char *str, int do_unbackslash)
{
#if !BASH_PATTERN_SUBST && !ENABLE_HUSH_CASE
	const int do_unbackslash = 1;
#endif
	char *argv[2], **list;

	debug_printf_expand("string_to_string<='%s'\n", str);
	/* This is generally an optimization, but it also
	 * handles "", which otherwise trips over !list[0] check below.
	 * (is this ever happens that we actually get str="" here?)
	 */
	if (!strchr(str, SPECIAL_VAR_SYMBOL) && !strchr(str, '\\')) {
		//TODO: Can use on strings with \ too, just unbackslash() them?
		debug_printf_expand("string_to_string(fast)=>'%s'\n", str);
		return xstrdup(str);
	}

	argv[0] = (char*)str;
	argv[1] = NULL;
	list = expand_variables(argv, do_unbackslash
			? EXP_FLAG_ESC_GLOB_CHARS | EXP_FLAG_SINGLEWORD
			: EXP_FLAG_SINGLEWORD
	);
	if (HUSH_DEBUG)
		if (!list[0] || list[1])
			bb_error_msg_and_die("BUG in varexp2");
	/* actually, just move string 2*sizeof(char*) bytes back */
	overlapping_strcpy((char*)list, list[0]);
	if (do_unbackslash)
		unbackslash((char*)list);
	debug_printf_expand("string_to_string=>'%s'\n", (char*)list);
	return (char*)list;
}

/* Used for "eval" builtin and case string */
static char* expand_strvec_to_string(char **argv)
{
	char **list;

	list = expand_variables(argv, EXP_FLAG_SINGLEWORD);
	/* Convert all NULs to spaces */
	if (list[0]) {
		int n = 1;
		while (list[n]) {
			if (HUSH_DEBUG)
				if (list[n-1] + strlen(list[n-1]) + 1 != list[n])
					bb_error_msg_and_die("BUG in varexp3");
			/* bash uses ' ' regardless of $IFS contents */
			list[n][-1] = ' ';
			n++;
		}
	}
	overlapping_strcpy((char*)list, list[0] ? list[0] : "");
	debug_printf_expand("strvec_to_string='%s'\n", (char*)list);
	return (char*)list;
}

static char **expand_assignments(char **argv, int count)
{
	int i;
	char **p;

	G.expanded_assignments = p = NULL;
	/* Expand assignments into one string each */
	for (i = 0; i < count; i++) {
		G.expanded_assignments = p = add_string_to_strings(p, expand_string_to_string(argv[i], /*unbackslash:*/ 1));
	}
	G.expanded_assignments = NULL;
	return p;
}


static void switch_off_special_sigs(unsigned mask)
{
	unsigned sig = 0;
	while ((mask >>= 1) != 0) {
		sig++;
		if (!(mask & 1))
			continue;
#if ENABLE_HUSH_TRAP
		if (G_traps) {
			if (G_traps[sig] && !G_traps[sig][0])
				/* trap is '', has to remain SIG_IGN */
				continue;
			free(G_traps[sig]);
			G_traps[sig] = NULL;
		}
#endif
		/* We are here only if no trap or trap was not '' */
		install_sighandler(sig, SIG_DFL);
	}
}

#if BB_MMU
/* never called */
void re_execute_shell(char ***to_free, const char *s,
		char *g_argv0, char **g_argv,
		char **builtin_argv) NORETURN;

static void reset_traps_to_defaults(void)
{
	/* This function is always called in a child shell
	 * after fork (not vfork, NOMMU doesn't use this function).
	 */
	IF_HUSH_TRAP(unsigned sig;)
	unsigned mask;

	/* Child shells are not interactive.
	 * SIGTTIN/SIGTTOU/SIGTSTP should not have special handling.
	 * Testcase: (while :; do :; done) + ^Z should background.
	 * Same goes for SIGTERM, SIGHUP, SIGINT.
	 */
	mask = (G.special_sig_mask & SPECIAL_INTERACTIVE_SIGS) | G_fatal_sig_mask;
	if (!G_traps && !mask)
		return; /* already no traps and no special sigs */

	/* Switch off special sigs */
	switch_off_special_sigs(mask);
# if ENABLE_HUSH_JOB
	G_fatal_sig_mask = 0;
# endif
	G.special_sig_mask &= ~SPECIAL_INTERACTIVE_SIGS;
	/* SIGQUIT,SIGCHLD and maybe SPECIAL_JOBSTOP_SIGS
	 * remain set in G.special_sig_mask */

# if ENABLE_HUSH_TRAP
	if (!G_traps)
		return;

	/* Reset all sigs to default except ones with empty traps */
	for (sig = 0; sig < NSIG; sig++) {
		if (!G_traps[sig])
			continue; /* no trap: nothing to do */
		if (!G_traps[sig][0])
			continue; /* empty trap: has to remain SIG_IGN */
		/* sig has non-empty trap, reset it: */
		free(G_traps[sig]);
		G_traps[sig] = NULL;
		/* There is no signal for trap 0 (EXIT) */
		if (sig == 0)
			continue;
		install_sighandler(sig, pick_sighandler(sig));
	}
# endif
}

#else /* !BB_MMU */

static void re_execute_shell(char ***to_free, const char *s,
		char *g_argv0, char **g_argv,
		char **builtin_argv) NORETURN;
static void re_execute_shell(char ***to_free, const char *s,
		char *g_argv0, char **g_argv,
		char **builtin_argv)
{
# define NOMMU_HACK_FMT ("-$%x:%x:%x:%x:%x:%llx" IF_HUSH_LOOPS(":%x"))
	/* delims + 2 * (number of bytes in printed hex numbers) */
	char param_buf[sizeof(NOMMU_HACK_FMT) + 2 * (sizeof(int)*6 + sizeof(long long)*1)];
	char *heredoc_argv[4];
	struct variable *cur;
# if ENABLE_HUSH_FUNCTIONS
	struct function *funcp;
# endif
	char **argv, **pp;
	unsigned cnt;
	unsigned long long empty_trap_mask;

	if (!g_argv0) { /* heredoc */
		argv = heredoc_argv;
		argv[0] = (char *) G.argv0_for_re_execing;
		argv[1] = (char *) "-<";
		argv[2] = (char *) s;
		argv[3] = NULL;
		pp = &argv[3]; /* used as pointer to empty environment */
		goto do_exec;
	}

	cnt = 0;
	pp = builtin_argv;
	if (pp) while (*pp++)
		cnt++;

	empty_trap_mask = 0;
	if (G_traps) {
		int sig;
		for (sig = 1; sig < NSIG; sig++) {
			if (G_traps[sig] && !G_traps[sig][0])
				empty_trap_mask |= 1LL << sig;
		}
	}

	sprintf(param_buf, NOMMU_HACK_FMT
			, (unsigned) G.root_pid
			, (unsigned) G.root_ppid
			, (unsigned) G.last_bg_pid
			, (unsigned) G.last_exitcode
			, cnt
			, empty_trap_mask
			IF_HUSH_LOOPS(, G.depth_of_loop)
			);
# undef NOMMU_HACK_FMT
	/* 1:hush 2:-$<pid>:<pid>:<exitcode>:<etc...> <vars...> <funcs...>
	 * 3:-c 4:<cmd> 5:<arg0> <argN...> 6:NULL
	 */
	cnt += 6;
	for (cur = G.top_var; cur; cur = cur->next) {
		if (!cur->flg_export || cur->flg_read_only)
			cnt += 2;
	}
# if ENABLE_HUSH_FUNCTIONS
	for (funcp = G.top_func; funcp; funcp = funcp->next)
		cnt += 3;
# endif
	pp = g_argv;
	while (*pp++)
		cnt++;
	*to_free = argv = pp = xzalloc(sizeof(argv[0]) * cnt);
	*pp++ = (char *) G.argv0_for_re_execing;
	*pp++ = param_buf;
	for (cur = G.top_var; cur; cur = cur->next) {
		if (strcmp(cur->varstr, hush_version_str) == 0)
			continue;
		if (cur->flg_read_only) {
			*pp++ = (char *) "-R";
			*pp++ = cur->varstr;
		} else if (!cur->flg_export) {
			*pp++ = (char *) "-V";
			*pp++ = cur->varstr;
		}
	}
# if ENABLE_HUSH_FUNCTIONS
	for (funcp = G.top_func; funcp; funcp = funcp->next) {
		*pp++ = (char *) "-F";
		*pp++ = funcp->name;
		*pp++ = funcp->body_as_string;
	}
# endif
	/* We can pass activated traps here. Say, -Tnn:trap_string
	 *
	 * However, POSIX says that subshells reset signals with traps
	 * to SIG_DFL.
	 * I tested bash-3.2 and it not only does that with true subshells
	 * of the form ( list ), but with any forked children shells.
	 * I set trap "echo W" WINCH; and then tried:
	 *
	 * { echo 1; sleep 20; echo 2; } &
	 * while true; do echo 1; sleep 20; echo 2; break; done &
	 * true | { echo 1; sleep 20; echo 2; } | cat
	 *
	 * In all these cases sending SIGWINCH to the child shell
	 * did not run the trap. If I add trap "echo V" WINCH;
	 * _inside_ group (just before echo 1), it works.
	 *
	 * I conclude it means we don't need to pass active traps here.
	 */
	*pp++ = (char *) "-c";
	*pp++ = (char *) s;
	if (builtin_argv) {
		while (*++builtin_argv)
			*pp++ = *builtin_argv;
		*pp++ = (char *) "";
	}
	*pp++ = g_argv0;
	while (*g_argv)
		*pp++ = *g_argv++;
	/* *pp = NULL; - is already there */
	pp = environ;

 do_exec:
	debug_printf_exec("re_execute_shell pid:%d cmd:'%s'\n", getpid(), s);
	/* Don't propagate SIG_IGN to the child */
	if (SPECIAL_JOBSTOP_SIGS != 0)
		switch_off_special_sigs(G.special_sig_mask & SPECIAL_JOBSTOP_SIGS);
	execve(bb_busybox_exec_path, argv, pp);
	/* Fallback. Useful for init=/bin/hush usage etc */
	if (argv[0][0] == '/')
		execve(argv[0], argv, pp);
	xfunc_error_retval = 127;
	bb_error_msg_and_die("can't re-execute the shell");
}
#endif  /* !BB_MMU */


static int run_and_free_list(struct pipe *pi);

/* Executing from string: eval, sh -c '...'
 *          or from file: /etc/profile, . file, sh <script>, sh (intereactive)
 * end_trigger controls how often we stop parsing
 * NUL: parse all, execute, return
 * ';': parse till ';' or newline, execute, repeat till EOF
 */
static void parse_and_run_stream(struct in_str *inp, int end_trigger)
{
	/* Why we need empty flag?
	 * An obscure corner case "false; ``; echo $?":
	 * empty command in `` should still set $? to 0.
	 * But we can't just set $? to 0 at the start,
	 * this breaks "false; echo `echo $?`" case.
	 */
	bool empty = 1;
	while (1) {
		struct pipe *pipe_list;

#if ENABLE_HUSH_INTERACTIVE
		if (end_trigger == ';')
			inp->promptmode = 0; /* PS1 */
#endif
		pipe_list = parse_stream(NULL, inp, end_trigger);
		if (!pipe_list || pipe_list == ERR_PTR) { /* EOF/error */
			/* If we are in "big" script
			 * (not in `cmd` or something similar)...
			 */
			if (pipe_list == ERR_PTR && end_trigger == ';') {
				/* Discard cached input (rest of line) */
				int ch = inp->last_char;
				while (ch != EOF && ch != '\n') {
					//bb_error_msg("Discarded:'%c'", ch);
					ch = i_getch(inp);
				}
				/* Force prompt */
				inp->p = NULL;
				/* This stream isn't empty */
				empty = 0;
				continue;
			}
			if (!pipe_list && empty)
				G.last_exitcode = 0;
			break;
		}
		debug_print_tree(pipe_list, 0);
		debug_printf_exec("parse_and_run_stream: run_and_free_list\n");
		run_and_free_list(pipe_list);
		empty = 0;
		if (G_flag_return_in_progress == 1)
			break;
	}
}

static void parse_and_run_string(const char *s)
{
	struct in_str input;
	setup_string_in_str(&input, s);
	parse_and_run_stream(&input, '\0');
}

static void parse_and_run_file(FILE *f)
{
	struct in_str input;
	setup_file_in_str(&input, f);
	parse_and_run_stream(&input, ';');
}

#if ENABLE_HUSH_TICK
static FILE *generate_stream_from_string(const char *s, pid_t *pid_p)
{
	pid_t pid;
	int channel[2];
# if !BB_MMU
	char **to_free = NULL;
# endif

	xpipe(channel);
	pid = BB_MMU ? xfork() : xvfork();
	if (pid == 0) { /* child */
		disable_restore_tty_pgrp_on_exit();
		/* Process substitution is not considered to be usual
		 * 'command execution'.
		 * SUSv3 says ctrl-Z should be ignored, ctrl-C should not.
		 */
		bb_signals(0
			+ (1 << SIGTSTP)
			+ (1 << SIGTTIN)
			+ (1 << SIGTTOU)
			, SIG_IGN);
		CLEAR_RANDOM_T(&G.random_gen); /* or else $RANDOM repeats in child */
		close(channel[0]); /* NB: close _first_, then move fd! */
		xmove_fd(channel[1], 1);
		/* Prevent it from trying to handle ctrl-z etc */
		IF_HUSH_JOB(G.run_list_level = 1;)
# if ENABLE_HUSH_TRAP
		/* Awful hack for `trap` or $(trap).
		 *
		 * http://www.opengroup.org/onlinepubs/009695399/utilities/trap.html
		 * contains an example where "trap" is executed in a subshell:
		 *
		 * save_traps=$(trap)
		 * ...
		 * eval "$save_traps"
		 *
		 * Standard does not say that "trap" in subshell shall print
		 * parent shell's traps. It only says that its output
		 * must have suitable form, but then, in the above example
		 * (which is not supposed to be normative), it implies that.
		 *
		 * bash (and probably other shell) does implement it
		 * (traps are reset to defaults, but "trap" still shows them),
		 * but as a result, "trap" logic is hopelessly messed up:
		 *
		 * # trap
		 * trap -- 'echo Ho' SIGWINCH  <--- we have a handler
		 * # (trap)        <--- trap is in subshell - no output (correct, traps are reset)
		 * # true | trap   <--- trap is in subshell - no output (ditto)
		 * # echo `true | trap`    <--- in subshell - output (but traps are reset!)
		 * trap -- 'echo Ho' SIGWINCH
		 * # echo `(trap)`         <--- in subshell in subshell - output
		 * trap -- 'echo Ho' SIGWINCH
		 * # echo `true | (trap)`  <--- in subshell in subshell in subshell - output!
		 * trap -- 'echo Ho' SIGWINCH
		 *
		 * The rules when to forget and when to not forget traps
		 * get really complex and nonsensical.
		 *
		 * Our solution: ONLY bare $(trap) or `trap` is special.
		 */
		s = skip_whitespace(s);
		if (is_prefixed_with(s, "trap")
		 && skip_whitespace(s + 4)[0] == '\0'
		) {
			static const char *const argv[] = { NULL, NULL };
			builtin_trap((char**)argv);
			fflush_all(); /* important */
			_exit(0);
		}
# endif
# if BB_MMU
		reset_traps_to_defaults();
		parse_and_run_string(s);
		_exit(G.last_exitcode);
# else
	/* We re-execute after vfork on NOMMU. This makes this script safe:
	 * yes "0123456789012345678901234567890" | dd bs=32 count=64k >BIG
	 * huge=`cat BIG` # was blocking here forever
	 * echo OK
	 */
		re_execute_shell(&to_free,
				s,
				G.global_argv[0],
				G.global_argv + 1,
				NULL);
# endif
	}

	/* parent */
	*pid_p = pid;
# if ENABLE_HUSH_FAST
	G.count_SIGCHLD++;
//bb_error_msg("[%d] fork in generate_stream_from_string:"
//		" G.count_SIGCHLD:%d G.handled_SIGCHLD:%d",
//		getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
# endif
	enable_restore_tty_pgrp_on_exit();
# if !BB_MMU
	free(to_free);
# endif
	close(channel[1]);
	return remember_FILE(xfdopen_for_read(channel[0]));
}

/* Return code is exit status of the process that is run. */
static int process_command_subs(o_string *dest, const char *s)
{
	FILE *fp;
	struct in_str pipe_str;
	pid_t pid;
	int status, ch, eol_cnt;

	fp = generate_stream_from_string(s, &pid);

	/* Now send results of command back into original context */
	setup_file_in_str(&pipe_str, fp);
	eol_cnt = 0;
	while ((ch = i_getch(&pipe_str)) != EOF) {
		if (ch == '\n') {
			eol_cnt++;
			continue;
		}
		while (eol_cnt) {
			o_addchr(dest, '\n');
			eol_cnt--;
		}
		o_addQchr(dest, ch);
	}

	debug_printf("done reading from `cmd` pipe, closing it\n");
	fclose_and_forget(fp);
	/* We need to extract exitcode. Test case
	 * "true; echo `sleep 1; false` $?"
	 * should print 1 */
	safe_waitpid(pid, &status, 0);
	debug_printf("child exited. returning its exitcode:%d\n", WEXITSTATUS(status));
	return WEXITSTATUS(status);
}
#endif /* ENABLE_HUSH_TICK */


static void setup_heredoc(struct redir_struct *redir)
{
	struct fd_pair pair;
	pid_t pid;
	int len, written;
	/* the _body_ of heredoc (misleading field name) */
	const char *heredoc = redir->rd_filename;
	char *expanded;
#if !BB_MMU
	char **to_free;
#endif

	expanded = NULL;
	if (!(redir->rd_dup & HEREDOC_QUOTED)) {
		expanded = encode_then_expand_string(heredoc, /*process_bkslash:*/ 1, /*unbackslash:*/ 1);
		if (expanded)
			heredoc = expanded;
	}
	len = strlen(heredoc);

	close(redir->rd_fd); /* often saves dup2+close in xmove_fd */
	xpiped_pair(pair);
	xmove_fd(pair.rd, redir->rd_fd);

	/* Try writing without forking. Newer kernels have
	 * dynamically growing pipes. Must use non-blocking write! */
	ndelay_on(pair.wr);
	while (1) {
		written = write(pair.wr, heredoc, len);
		if (written <= 0)
			break;
		len -= written;
		if (len == 0) {
			close(pair.wr);
			free(expanded);
			return;
		}
		heredoc += written;
	}
	ndelay_off(pair.wr);

	/* Okay, pipe buffer was not big enough */
	/* Note: we must not create a stray child (bastard? :)
	 * for the unsuspecting parent process. Child creates a grandchild
	 * and exits before parent execs the process which consumes heredoc
	 * (that exec happens after we return from this function) */
#if !BB_MMU
	to_free = NULL;
#endif
	pid = xvfork();
	if (pid == 0) {
		/* child */
		disable_restore_tty_pgrp_on_exit();
		pid = BB_MMU ? xfork() : xvfork();
		if (pid != 0)
			_exit(0);
		/* grandchild */
		close(redir->rd_fd); /* read side of the pipe */
#if BB_MMU
		full_write(pair.wr, heredoc, len); /* may loop or block */
		_exit(0);
#else
		/* Delegate blocking writes to another process */
		xmove_fd(pair.wr, STDOUT_FILENO);
		re_execute_shell(&to_free, heredoc, NULL, NULL, NULL);
#endif
	}
	/* parent */
#if ENABLE_HUSH_FAST
	G.count_SIGCHLD++;
//bb_error_msg("[%d] fork in setup_heredoc: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
#endif
	enable_restore_tty_pgrp_on_exit();
#if !BB_MMU
	free(to_free);
#endif
	close(pair.wr);
	free(expanded);
	wait(NULL); /* wait till child has died */
}

struct squirrel {
	int orig_fd;
	int moved_to;
	/* moved_to = n: fd was moved to n; restore back to orig_fd after redir */
	/* moved_to = -1: fd was opened by redirect; close orig_fd after redir */
};

static struct squirrel *append_squirrel(struct squirrel *sq, int i, int orig, int moved)
{
	sq = xrealloc(sq, (i + 2) * sizeof(sq[0]));
	sq[i].orig_fd = orig;
	sq[i].moved_to = moved;
	sq[i+1].orig_fd = -1; /* end marker */
	return sq;
}

static struct squirrel *add_squirrel(struct squirrel *sq, int fd, int avoid_fd)
{
	int moved_to;
	int i;

	if (sq) for (i = 0; sq[i].orig_fd >= 0; i++) {
		/* If we collide with an already moved fd... */
		if (fd == sq[i].moved_to) {
			sq[i].moved_to = fcntl_F_DUPFD(sq[i].moved_to, avoid_fd);
			debug_printf_redir("redirect_fd %d: already busy, moving to %d\n", fd, sq[i].moved_to);
			if (sq[i].moved_to < 0) /* what? */
				xfunc_die();
			return sq;
		}
		if (fd == sq[i].orig_fd) {
			/* Example: echo Hello >/dev/null 1>&2 */
			debug_printf_redir("redirect_fd %d: already moved\n", fd);
			return sq;
		}
	}

	/* If this fd is open, we move and remember it; if it's closed, moved_to = -1 */
	moved_to = fcntl_F_DUPFD(fd, avoid_fd);
	debug_printf_redir("redirect_fd %d: previous fd is moved to %d (-1 if it was closed)\n", fd, moved_to);
	if (moved_to < 0 && errno != EBADF)
		xfunc_die();
	return append_squirrel(sq, i, fd, moved_to);
}

static struct squirrel *add_squirrel_closed(struct squirrel *sq, int fd)
{
	int i;

	if (sq) for (i = 0; sq[i].orig_fd >= 0; i++) {
		/* If we collide with an already moved fd... */
		if (fd == sq[i].orig_fd) {
			/* Examples:
			 * "echo 3>FILE 3>&- 3>FILE"
			 * "echo 3>&- 3>FILE"
			 * No need for last redirect to insert
			 * another "need to close 3" indicator.
			 */
			debug_printf_redir("redirect_fd %d: already moved or closed\n", fd);
			return sq;
		}
	}

	debug_printf_redir("redirect_fd %d: previous fd was closed\n", fd);
	return append_squirrel(sq, i, fd, -1);
}

/* fd: redirect wants this fd to be used (e.g. 3>file).
 * Move all conflicting internally used fds,
 * and remember them so that we can restore them later.
 */
static int save_fd_on_redirect(int fd, int avoid_fd, struct squirrel **sqp)
{
	if (avoid_fd < 9) /* the important case here is that it can be -1 */
		avoid_fd = 9;

#if ENABLE_HUSH_INTERACTIVE
	if (fd == G.interactive_fd) {
		/* Testcase: "ls -l /proc/$$/fd 255>&-" should work */
		G.interactive_fd = xdup_CLOEXEC_and_close(G.interactive_fd, avoid_fd);
		debug_printf_redir("redirect_fd %d: matches interactive_fd, moving it to %d\n", fd, G.interactive_fd);
		return 1; /* "we closed fd" */
	}
#endif
	/* Are we called from setup_redirects(squirrel==NULL)? Two cases:
	 * (1) Redirect in a forked child. No need to save FILEs' fds,
	 * we aren't going to use them anymore, ok to trash.
	 * (2) "exec 3>FILE". Bummer. We can save script FILEs' fds,
	 * but how are we doing to restore them?
	 * "fileno(fd) = new_fd" can't be done.
	 */
	if (!sqp)
		return 0;

	/* If this one of script's fds? */
	if (save_FILEs_on_redirect(fd, avoid_fd))
		return 1; /* yes. "we closed fd" */

	/* Check whether it collides with any open fds (e.g. stdio), save fds as needed */
	*sqp = add_squirrel(*sqp, fd, avoid_fd);
	return 0; /* "we did not close fd" */
}

static void restore_redirects(struct squirrel *sq)
{
	if (sq) {
		int i;
		for (i = 0; sq[i].orig_fd >= 0; i++) {
			if (sq[i].moved_to >= 0) {
				/* We simply die on error */
				debug_printf_redir("restoring redirected fd from %d to %d\n", sq[i].moved_to, sq[i].orig_fd);
				xmove_fd(sq[i].moved_to, sq[i].orig_fd);
			} else {
				/* cmd1 9>FILE; cmd2_should_see_fd9_closed */
				debug_printf_redir("restoring redirected fd %d: closing it\n", sq[i].orig_fd);
				close(sq[i].orig_fd);
			}
		}
		free(sq);
	}

	/* If moved, G.interactive_fd stays on new fd, not restoring it */

	restore_redirected_FILEs();
}

#if ENABLE_FEATURE_SH_STANDALONE && BB_MMU
static void close_saved_fds_and_FILE_fds(void)
{
	if (G_interactive_fd)
		close(G_interactive_fd);
	close_all_FILE_list();
}
#endif

static int internally_opened_fd(int fd, struct squirrel *sq)
{
	int i;

#if ENABLE_HUSH_INTERACTIVE
	if (fd == G.interactive_fd)
		return 1;
#endif
	/* If this one of script's fds? */
	if (fd_in_FILEs(fd))
		return 1;

	if (sq) for (i = 0; sq[i].orig_fd >= 0; i++) {
		if (fd == sq[i].moved_to)
			return 1;
	}
	return 0;
}

/* squirrel != NULL means we squirrel away copies of stdin, stdout,
 * and stderr if they are redirected. */
static int setup_redirects(struct command *prog, struct squirrel **sqp)
{
	struct redir_struct *redir;

	for (redir = prog->redirects; redir; redir = redir->next) {
		int newfd;
		int closed;

		if (redir->rd_type == REDIRECT_HEREDOC2) {
			/* "rd_fd<<HERE" case */
			save_fd_on_redirect(redir->rd_fd, /*avoid:*/ 0, sqp);
			/* for REDIRECT_HEREDOC2, rd_filename holds _contents_
			 * of the heredoc */
			debug_printf_parse("set heredoc '%s'\n",
					redir->rd_filename);
			setup_heredoc(redir);
			continue;
		}

		if (redir->rd_dup == REDIRFD_TO_FILE) {
			/* "rd_fd<*>file" case (<*> is <,>,>>,<>) */
			char *p;
			int mode;

			if (redir->rd_filename == NULL) {
				/*
				 * Examples:
				 * "cmd >" (no filename)
				 * "cmd > <file" (2nd redirect starts too early)
				 */
				syntax_error("invalid redirect");
				continue;
			}
			mode = redir_table[redir->rd_type].mode;
			p = expand_string_to_string(redir->rd_filename, /*unbackslash:*/ 1);
			newfd = open_or_warn(p, mode);
			free(p);
			if (newfd < 0) {
				/* Error message from open_or_warn can be lost
				 * if stderr has been redirected, but bash
				 * and ash both lose it as well
				 * (though zsh doesn't!)
				 */
				return 1;
			}
			if (newfd == redir->rd_fd && sqp) {
				/* open() gave us precisely the fd we wanted.
				 * This means that this fd was not busy
				 * (not opened to anywhere).
				 * Remember to close it on restore:
				 */
				*sqp = add_squirrel_closed(*sqp, newfd);
				debug_printf_redir("redir to previously closed fd %d\n", newfd);
			}
		} else {
			/* "rd_fd>&rd_dup" or "rd_fd>&-" case */
			newfd = redir->rd_dup;
		}

		if (newfd == redir->rd_fd)
			continue;

		/* if "N>FILE": move newfd to redir->rd_fd */
		/* if "N>&M": dup newfd to redir->rd_fd */
		/* if "N>&-": close redir->rd_fd (newfd is REDIRFD_CLOSE) */

		closed = save_fd_on_redirect(redir->rd_fd, /*avoid:*/ newfd, sqp);
		if (newfd == REDIRFD_CLOSE) {
			/* "N>&-" means "close me" */
			if (!closed) {
				/* ^^^ optimization: saving may already
				 * have closed it. If not... */
				close(redir->rd_fd);
			}
			/* Sometimes we do another close on restore, getting EBADF.
			 * Consider "echo 3>FILE 3>&-"
			 * first redirect remembers "need to close 3",
			 * and second redirect closes 3! Restore code then closes 3 again.
			 */
		} else {
			/* if newfd is a script fd or saved fd, simulate EBADF */
			if (internally_opened_fd(newfd, sqp ? *sqp : NULL)) {
				//errno = EBADF;
				//bb_perror_msg_and_die("can't duplicate file descriptor");
				newfd = -1; /* same effect as code above */
			}
			xdup2(newfd, redir->rd_fd);
			if (redir->rd_dup == REDIRFD_TO_FILE)
				/* "rd_fd > FILE" */
				close(newfd);
			/* else: "rd_fd > rd_dup" */
		}
	}
	return 0;
}

static char *find_in_path(const char *arg)
{
	char *ret = NULL;
	const char *PATH = get_local_var_value("PATH");

	if (!PATH)
		return NULL;

	while (1) {
		const char *end = strchrnul(PATH, ':');
		int sz = end - PATH; /* must be int! */

		free(ret);
		if (sz != 0) {
			ret = xasprintf("%.*s/%s", sz, PATH, arg);
		} else {
			/* We have xxx::yyyy in $PATH,
			 * it means "use current dir" */
			ret = xstrdup(arg);
		}
		if (access(ret, F_OK) == 0)
			break;

		if (*end == '\0') {
			free(ret);
			return NULL;
		}
		PATH = end + 1;
	}

	return ret;
}

static const struct built_in_command *find_builtin_helper(const char *name,
		const struct built_in_command *x,
		const struct built_in_command *end)
{
	while (x != end) {
		if (strcmp(name, x->b_cmd) != 0) {
			x++;
			continue;
		}
		debug_printf_exec("found builtin '%s'\n", name);
		return x;
	}
	return NULL;
}
static const struct built_in_command *find_builtin1(const char *name)
{
	return find_builtin_helper(name, bltins1, &bltins1[ARRAY_SIZE(bltins1)]);
}
static const struct built_in_command *find_builtin(const char *name)
{
	const struct built_in_command *x = find_builtin1(name);
	if (x)
		return x;
	return find_builtin_helper(name, bltins2, &bltins2[ARRAY_SIZE(bltins2)]);
}

#if ENABLE_HUSH_FUNCTIONS
static struct function **find_function_slot(const char *name)
{
	struct function **funcpp = &G.top_func;
	while (*funcpp) {
		if (strcmp(name, (*funcpp)->name) == 0) {
			break;
		}
		funcpp = &(*funcpp)->next;
	}
	return funcpp;
}

static const struct function *find_function(const char *name)
{
	const struct function *funcp = *find_function_slot(name);
	if (funcp)
		debug_printf_exec("found function '%s'\n", name);
	return funcp;
}

/* Note: takes ownership on name ptr */
static struct function *new_function(char *name)
{
	struct function **funcpp = find_function_slot(name);
	struct function *funcp = *funcpp;

	if (funcp != NULL) {
		struct command *cmd = funcp->parent_cmd;
		debug_printf_exec("func %p parent_cmd %p\n", funcp, cmd);
		if (!cmd) {
			debug_printf_exec("freeing & replacing function '%s'\n", funcp->name);
			free(funcp->name);
			/* Note: if !funcp->body, do not free body_as_string!
			 * This is a special case of "-F name body" function:
			 * body_as_string was not malloced! */
			if (funcp->body) {
				free_pipe_list(funcp->body);
# if !BB_MMU
				free(funcp->body_as_string);
# endif
			}
		} else {
			debug_printf_exec("reinserting in tree & replacing function '%s'\n", funcp->name);
			cmd->argv[0] = funcp->name;
			cmd->group = funcp->body;
# if !BB_MMU
			cmd->group_as_string = funcp->body_as_string;
# endif
		}
	} else {
		debug_printf_exec("remembering new function '%s'\n", name);
		funcp = *funcpp = xzalloc(sizeof(*funcp));
		/*funcp->next = NULL;*/
	}

	funcp->name = name;
	return funcp;
}

# if ENABLE_HUSH_UNSET
static void unset_func(const char *name)
{
	struct function **funcpp = find_function_slot(name);
	struct function *funcp = *funcpp;

	if (funcp != NULL) {
		debug_printf_exec("freeing function '%s'\n", funcp->name);
		*funcpp = funcp->next;
		/* funcp is unlinked now, deleting it.
		 * Note: if !funcp->body, the function was created by
		 * "-F name body", do not free ->body_as_string
		 * and ->name as they were not malloced. */
		if (funcp->body) {
			free_pipe_list(funcp->body);
			free(funcp->name);
#  if !BB_MMU
			free(funcp->body_as_string);
#  endif
		}
		free(funcp);
	}
}
# endif

# if BB_MMU
#define exec_function(to_free, funcp, argv) \
	exec_function(funcp, argv)
# endif
static void exec_function(char ***to_free,
		const struct function *funcp,
		char **argv) NORETURN;
static void exec_function(char ***to_free,
		const struct function *funcp,
		char **argv)
{
# if BB_MMU
	int n;

	argv[0] = G.global_argv[0];
	G.global_argv = argv;
	G.global_argc = n = 1 + string_array_len(argv + 1);

// Example when we are here: "cmd | func"
// func will run with saved-redirect fds open.
// $ f() { echo /proc/self/fd/*; }
// $ true | f
// /proc/self/fd/0 /proc/self/fd/1 /proc/self/fd/2 /proc/self/fd/255 /proc/self/fd/3
// stdio^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ G_interactive_fd^ DIR fd for glob
// Same in script:
// $ . ./SCRIPT
// /proc/self/fd/0 /proc/self/fd/1 /proc/self/fd/2 /proc/self/fd/255 /proc/self/fd/3 /proc/self/fd/4
// stdio^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ G_interactive_fd^ opened ./SCRIPT DIR fd for glob
// They are CLOEXEC so external programs won't see them, but
// for "more correctness" we might want to close those extra fds here:
//?	close_saved_fds_and_FILE_fds();

	/* "we are in function, ok to use return" */
	G_flag_return_in_progress = -1;
	IF_HUSH_LOCAL(G.func_nest_level++;)

	/* On MMU, funcp->body is always non-NULL */
	n = run_list(funcp->body);
	fflush_all();
	_exit(n);
# else
//?	close_saved_fds_and_FILE_fds();

//TODO: check whether "true | func_with_return" works

	re_execute_shell(to_free,
			funcp->body_as_string,
			G.global_argv[0],
			argv + 1,
			NULL);
# endif
}

static int run_function(const struct function *funcp, char **argv)
{
	int rc;
	save_arg_t sv;
	smallint sv_flg;

	save_and_replace_G_args(&sv, argv);

	/* "we are in function, ok to use return" */
	sv_flg = G_flag_return_in_progress;
	G_flag_return_in_progress = -1;
	IF_HUSH_LOCAL(G.func_nest_level++;)

	/* On MMU, funcp->body is always non-NULL */
# if !BB_MMU
	if (!funcp->body) {
		/* Function defined by -F */
		parse_and_run_string(funcp->body_as_string);
		rc = G.last_exitcode;
	} else
# endif
	{
		rc = run_list(funcp->body);
	}

# if ENABLE_HUSH_LOCAL
	{
		struct variable *var;
		struct variable **var_pp;

		var_pp = &G.top_var;
		while ((var = *var_pp) != NULL) {
			if (var->func_nest_level < G.func_nest_level) {
				var_pp = &var->next;
				continue;
			}
			/* Unexport */
			if (var->flg_export)
				bb_unsetenv(var->varstr);
			/* Remove from global list */
			*var_pp = var->next;
			/* Free */
			if (!var->max_len)
				free(var->varstr);
			free(var);
		}
		G.func_nest_level--;
	}
# endif
	G_flag_return_in_progress = sv_flg;

	restore_G_args(&sv, argv);

	return rc;
}
#endif /* ENABLE_HUSH_FUNCTIONS */


#if BB_MMU
#define exec_builtin(to_free, x, argv) \
	exec_builtin(x, argv)
#else
#define exec_builtin(to_free, x, argv) \
	exec_builtin(to_free, argv)
#endif
static void exec_builtin(char ***to_free,
		const struct built_in_command *x,
		char **argv) NORETURN;
static void exec_builtin(char ***to_free,
		const struct built_in_command *x,
		char **argv)
{
#if BB_MMU
	int rcode;
	fflush_all();
//?	close_saved_fds_and_FILE_fds();
	rcode = x->b_function(argv);
	fflush_all();
	_exit(rcode);
#else
	fflush_all();
	/* On NOMMU, we must never block!
	 * Example: { sleep 99 | read line; } & echo Ok
	 */
	re_execute_shell(to_free,
			argv[0],
			G.global_argv[0],
			G.global_argv + 1,
			argv);
#endif
}


static void execvp_or_die(char **argv) NORETURN;
static void execvp_or_die(char **argv)
{
	int e;
	debug_printf_exec("execing '%s'\n", argv[0]);
	/* Don't propagate SIG_IGN to the child */
	if (SPECIAL_JOBSTOP_SIGS != 0)
		switch_off_special_sigs(G.special_sig_mask & SPECIAL_JOBSTOP_SIGS);
	execvp(argv[0], argv);
	e = 2;
	if (errno == EACCES) e = 126;
	if (errno == ENOENT) e = 127;
	bb_perror_msg("can't execute '%s'", argv[0]);
	_exit(e);
}

#if ENABLE_HUSH_MODE_X
static void dump_cmd_in_x_mode(char **argv)
{
	if (G_x_mode && argv) {
		/* We want to output the line in one write op */
		char *buf, *p;
		int len;
		int n;

		len = 3;
		n = 0;
		while (argv[n])
			len += strlen(argv[n++]) + 1;
		buf = xmalloc(len);
		buf[0] = '+';
		p = buf + 1;
		n = 0;
		while (argv[n])
			p += sprintf(p, " %s", argv[n++]);
		*p++ = '\n';
		*p = '\0';
		fputs(buf, stderr);
		free(buf);
	}
}
#else
# define dump_cmd_in_x_mode(argv) ((void)0)
#endif

#if BB_MMU
#define pseudo_exec_argv(nommu_save, argv, assignment_cnt, argv_expanded) \
	pseudo_exec_argv(argv, assignment_cnt, argv_expanded)
#define pseudo_exec(nommu_save, command, argv_expanded) \
	pseudo_exec(command, argv_expanded)
#endif

/* Called after [v]fork() in run_pipe, or from builtin_exec.
 * Never returns.
 * Don't exit() here.  If you don't exec, use _exit instead.
 * The at_exit handlers apparently confuse the calling process,
 * in particular stdin handling. Not sure why? -- because of vfork! (vda)
 */
static void pseudo_exec_argv(nommu_save_t *nommu_save,
		char **argv, int assignment_cnt,
		char **argv_expanded) NORETURN;
static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
		char **argv, int assignment_cnt,
		char **argv_expanded)
{
	char **new_env;

	new_env = expand_assignments(argv, assignment_cnt);
	dump_cmd_in_x_mode(new_env);

	if (!argv[assignment_cnt]) {
		/* Case when we are here: ... | var=val | ...
		 * (note that we do not exit early, i.e., do not optimize out
		 * expand_assignments(): think about ... | var=`sleep 1` | ...
		 */
		free_strings(new_env);
		_exit(EXIT_SUCCESS);
	}

#if BB_MMU
	set_vars_and_save_old(new_env);
	free(new_env); /* optional */
	/* we can also destroy set_vars_and_save_old's return value,
	 * to save memory */
#else
	nommu_save->new_env = new_env;
	nommu_save->old_vars = set_vars_and_save_old(new_env);
#endif

	if (argv_expanded) {
		argv = argv_expanded;
	} else {
		argv = expand_strvec_to_strvec(argv + assignment_cnt);
#if !BB_MMU
		nommu_save->argv = argv;
#endif
	}
	dump_cmd_in_x_mode(argv);

#if ENABLE_FEATURE_SH_STANDALONE || BB_MMU
	if (strchr(argv[0], '/') != NULL)
		goto skip;
#endif

#if ENABLE_HUSH_FUNCTIONS
	/* Check if the command matches any functions (this goes before bltins) */
	{
		const struct function *funcp = find_function(argv[0]);
		if (funcp) {
			exec_function(&nommu_save->argv_from_re_execing, funcp, argv);
		}
	}
#endif

	/* Check if the command matches any of the builtins.
	 * Depending on context, this might be redundant.  But it's
	 * easier to waste a few CPU cycles than it is to figure out
	 * if this is one of those cases.
	 */
	{
		/* On NOMMU, it is more expensive to re-execute shell
		 * just in order to run echo or test builtin.
		 * It's better to skip it here and run corresponding
		 * non-builtin later. */
		const struct built_in_command *x;
		x = BB_MMU ? find_builtin(argv[0]) : find_builtin1(argv[0]);
		if (x) {
			exec_builtin(&nommu_save->argv_from_re_execing, x, argv);
		}
	}

#if ENABLE_FEATURE_SH_STANDALONE
	/* Check if the command matches any busybox applets */
	{
		int a = find_applet_by_name(argv[0]);
		if (a >= 0) {
# if BB_MMU /* see above why on NOMMU it is not allowed */
			if (APPLET_IS_NOEXEC(a)) {
				/* Do not leak open fds from opened script files etc.
				 * Testcase: interactive "ls -l /proc/self/fd"
				 * should not show tty fd open.
				 */
				close_saved_fds_and_FILE_fds();
//FIXME: should also close saved redir fds
				/* Without this, "rm -i FILE" can't be ^C'ed: */
				switch_off_special_sigs(G.special_sig_mask);
				debug_printf_exec("running applet '%s'\n", argv[0]);
				run_noexec_applet_and_exit(a, argv[0], argv);
			}
# endif
			/* Re-exec ourselves */
			debug_printf_exec("re-execing applet '%s'\n", argv[0]);
			/* Don't propagate SIG_IGN to the child */
			if (SPECIAL_JOBSTOP_SIGS != 0)
				switch_off_special_sigs(G.special_sig_mask & SPECIAL_JOBSTOP_SIGS);
			execv(bb_busybox_exec_path, argv);
			/* If they called chroot or otherwise made the binary no longer
			 * executable, fall through */
		}
	}
#endif

#if ENABLE_FEATURE_SH_STANDALONE || BB_MMU
 skip:
#endif
	execvp_or_die(argv);
}

/* Called after [v]fork() in run_pipe
 */
static void pseudo_exec(nommu_save_t *nommu_save,
		struct command *command,
		char **argv_expanded) NORETURN;
static void pseudo_exec(nommu_save_t *nommu_save,
		struct command *command,
		char **argv_expanded)
{
	if (command->argv) {
		pseudo_exec_argv(nommu_save, command->argv,
				command->assignment_cnt, argv_expanded);
	}

	if (command->group) {
		/* Cases when we are here:
		 * ( list )
		 * { list } &
		 * ... | ( list ) | ...
		 * ... | { list } | ...
		 */
#if BB_MMU
		int rcode;
		debug_printf_exec("pseudo_exec: run_list\n");
		reset_traps_to_defaults();
		rcode = run_list(command->group);
		/* OK to leak memory by not calling free_pipe_list,
		 * since this process is about to exit */
		_exit(rcode);
#else
		re_execute_shell(&nommu_save->argv_from_re_execing,
				command->group_as_string,
				G.global_argv[0],
				G.global_argv + 1,
				NULL);
#endif
	}

	/* Case when we are here: ... | >file */
	debug_printf_exec("pseudo_exec'ed null command\n");
	_exit(EXIT_SUCCESS);
}

#if ENABLE_HUSH_JOB
static const char *get_cmdtext(struct pipe *pi)
{
	char **argv;
	char *p;
	int len;

	/* This is subtle. ->cmdtext is created only on first backgrounding.
	 * (Think "cat, <ctrl-z>, fg, <ctrl-z>, fg, <ctrl-z>...." here...)
	 * On subsequent bg argv is trashed, but we won't use it */
	if (pi->cmdtext)
		return pi->cmdtext;

	argv = pi->cmds[0].argv;
	if (!argv) {
		pi->cmdtext = xzalloc(1);
		return pi->cmdtext;
	}
	len = 0;
	do {
		len += strlen(*argv) + 1;
	} while (*++argv);
	p = xmalloc(len);
	pi->cmdtext = p;
	argv = pi->cmds[0].argv;
	do {
		p = stpcpy(p, *argv);
		*p++ = ' ';
	} while (*++argv);
	p[-1] = '\0';
	return pi->cmdtext;
}

static void remove_job_from_table(struct pipe *pi)
{
	struct pipe *prev_pipe;

	if (pi == G.job_list) {
		G.job_list = pi->next;
	} else {
		prev_pipe = G.job_list;
		while (prev_pipe->next != pi)
			prev_pipe = prev_pipe->next;
		prev_pipe->next = pi->next;
	}
	G.last_jobid = 0;
	if (G.job_list)
		G.last_jobid = G.job_list->jobid;
}

static void delete_finished_job(struct pipe *pi)
{
	remove_job_from_table(pi);
	free_pipe(pi);
}

static void clean_up_last_dead_job(void)
{
	if (G.job_list && !G.job_list->alive_cmds)
		delete_finished_job(G.job_list);
}

static void insert_job_into_table(struct pipe *pi)
{
	struct pipe *job, **jobp;
	int i;

	clean_up_last_dead_job();

	/* Find the end of the list, and find next job ID to use */
	i = 0;
	jobp = &G.job_list;
	while ((job = *jobp) != NULL) {
		if (job->jobid > i)
			i = job->jobid;
		jobp = &job->next;
	}
	pi->jobid = i + 1;

	/* Create a new job struct at the end */
	job = *jobp = xmemdup(pi, sizeof(*pi));
	job->next = NULL;
	job->cmds = xzalloc(sizeof(pi->cmds[0]) * pi->num_cmds);
	/* Cannot copy entire pi->cmds[] vector! This causes double frees */
	for (i = 0; i < pi->num_cmds; i++) {
		job->cmds[i].pid = pi->cmds[i].pid;
		/* all other fields are not used and stay zero */
	}
	job->cmdtext = xstrdup(get_cmdtext(pi));

	if (G_interactive_fd)
		printf("[%u] %u %s\n", job->jobid, (unsigned)job->cmds[0].pid, job->cmdtext);
	G.last_jobid = job->jobid;
}
#endif /* JOB */

static int job_exited_or_stopped(struct pipe *pi)
{
	int rcode, i;

	if (pi->alive_cmds != pi->stopped_cmds)
		return -1;

	/* All processes in fg pipe have exited or stopped */
	rcode = 0;
	i = pi->num_cmds;
	while (--i >= 0) {
		rcode = pi->cmds[i].cmd_exitcode;
		/* usually last process gives overall exitstatus,
		 * but with "set -o pipefail", last *failed* process does */
		if (G.o_opt[OPT_O_PIPEFAIL] == 0 || rcode != 0)
			break;
	}
	IF_HAS_KEYWORDS(if (pi->pi_inverted) rcode = !rcode;)
	return rcode;
}

static int process_wait_result(struct pipe *fg_pipe, pid_t childpid, int status)
{
#if ENABLE_HUSH_JOB
	struct pipe *pi;
#endif
	int i, dead;

	dead = WIFEXITED(status) || WIFSIGNALED(status);

#if DEBUG_JOBS
	if (WIFSTOPPED(status))
		debug_printf_jobs("pid %d stopped by sig %d (exitcode %d)\n",
				childpid, WSTOPSIG(status), WEXITSTATUS(status));
	if (WIFSIGNALED(status))
		debug_printf_jobs("pid %d killed by sig %d (exitcode %d)\n",
				childpid, WTERMSIG(status), WEXITSTATUS(status));
	if (WIFEXITED(status))
		debug_printf_jobs("pid %d exited, exitcode %d\n",
				childpid, WEXITSTATUS(status));
#endif
	/* Were we asked to wait for a fg pipe? */
	if (fg_pipe) {
		i = fg_pipe->num_cmds;

		while (--i >= 0) {
			int rcode;

			debug_printf_jobs("check pid %d\n", fg_pipe->cmds[i].pid);
			if (fg_pipe->cmds[i].pid != childpid)
				continue;
			if (dead) {
				int ex;
				fg_pipe->cmds[i].pid = 0;
				fg_pipe->alive_cmds--;
				ex = WEXITSTATUS(status);
				/* bash prints killer signal's name for *last*
				 * process in pipe (prints just newline for SIGINT/SIGPIPE).
				 * Mimic this. Example: "sleep 5" + (^\ or kill -QUIT)
				 */
				if (WIFSIGNALED(status)) {
					int sig = WTERMSIG(status);
					if (i == fg_pipe->num_cmds-1)
						/* TODO: use strsignal() instead for bash compat? but that's bloat... */
						puts(sig == SIGINT || sig == SIGPIPE ? "" : get_signame(sig));
					/* TODO: if (WCOREDUMP(status)) + " (core dumped)"; */
					/* TODO: MIPS has 128 sigs (1..128), what if sig==128 here?
					 * Maybe we need to use sig | 128? */
					ex = sig + 128;
				}
				fg_pipe->cmds[i].cmd_exitcode = ex;
			} else {
				fg_pipe->stopped_cmds++;
			}
			debug_printf_jobs("fg_pipe: alive_cmds %d stopped_cmds %d\n",
					fg_pipe->alive_cmds, fg_pipe->stopped_cmds);
			rcode = job_exited_or_stopped(fg_pipe);
			if (rcode >= 0) {
/* Note: *non-interactive* bash does not continue if all processes in fg pipe
 * are stopped. Testcase: "cat | cat" in a script (not on command line!)
 * and "killall -STOP cat" */
				if (G_interactive_fd) {
#if ENABLE_HUSH_JOB
					if (fg_pipe->alive_cmds != 0)
						insert_job_into_table(fg_pipe);
#endif
					return rcode;
				}
				if (fg_pipe->alive_cmds == 0)
					return rcode;
			}
			/* There are still running processes in the fg_pipe */
			return -1;
		}
		/* It wasn't in fg_pipe, look for process in bg pipes */
	}

#if ENABLE_HUSH_JOB
	/* We were asked to wait for bg or orphaned children */
	/* No need to remember exitcode in this case */
	for (pi = G.job_list; pi; pi = pi->next) {
		for (i = 0; i < pi->num_cmds; i++) {
			if (pi->cmds[i].pid == childpid)
				goto found_pi_and_prognum;
		}
	}
	/* Happens when shell is used as init process (init=/bin/sh) */
	debug_printf("checkjobs: pid %d was not in our list!\n", childpid);
	return -1; /* this wasn't a process from fg_pipe */

 found_pi_and_prognum:
	if (dead) {
		/* child exited */
		int rcode = WEXITSTATUS(status);
		if (WIFSIGNALED(status))
			rcode = 128 + WTERMSIG(status);
		pi->cmds[i].cmd_exitcode = rcode;
		if (G.last_bg_pid == pi->cmds[i].pid)
			G.last_bg_pid_exitcode = rcode;
		pi->cmds[i].pid = 0;
		pi->alive_cmds--;
		if (!pi->alive_cmds) {
			if (G_interactive_fd) {
				printf(JOB_STATUS_FORMAT, pi->jobid,
						"Done", pi->cmdtext);
				delete_finished_job(pi);
			} else {
/*
 * bash deletes finished jobs from job table only in interactive mode,
 * after "jobs" cmd, or if pid of a new process matches one of the old ones
 * (see cleanup_dead_jobs(), delete_old_job(), J_NOTIFIED in bash source).
 * Testcase script: "(exit 3) & sleep 1; wait %1; echo $?" prints 3 in bash.
 * We only retain one "dead" job, if it's the single job on the list.
 * This covers most of real-world scenarios where this is useful.
 */
				if (pi != G.job_list)
					delete_finished_job(pi);
			}
		}
	} else {
		/* child stopped */
		pi->stopped_cmds++;
	}
#endif
	return -1; /* this wasn't a process from fg_pipe */
}

/* Check to see if any processes have exited -- if they have,
 * figure out why and see if a job has completed.
 *
 * If non-NULL fg_pipe: wait for its completion or stop.
 * Return its exitcode or zero if stopped.
 *
 * Alternatively (fg_pipe == NULL, waitfor_pid != 0):
 * waitpid(WNOHANG), if waitfor_pid exits or stops, return exitcode+1,
 * else return <0 if waitpid errors out (e.g. ECHILD: nothing to wait for)
 * or 0 if no children changed status.
 *
 * Alternatively (fg_pipe == NULL, waitfor_pid == 0),
 * return <0 if waitpid errors out (e.g. ECHILD: nothing to wait for)
 * or 0 if no children changed status.
 */
static int checkjobs(struct pipe *fg_pipe, pid_t waitfor_pid)
{
	int attributes;
	int status;
	int rcode = 0;

	debug_printf_jobs("checkjobs %p\n", fg_pipe);

	attributes = WUNTRACED;
	if (fg_pipe == NULL)
		attributes |= WNOHANG;

	errno = 0;
#if ENABLE_HUSH_FAST
	if (G.handled_SIGCHLD == G.count_SIGCHLD) {
//bb_error_msg("[%d] checkjobs: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d children?:%d fg_pipe:%p",
//getpid(), G.count_SIGCHLD, G.handled_SIGCHLD, G.we_have_children, fg_pipe);
		/* There was neither fork nor SIGCHLD since last waitpid */
		/* Avoid doing waitpid syscall if possible */
		if (!G.we_have_children) {
			errno = ECHILD;
			return -1;
		}
		if (fg_pipe == NULL) { /* is WNOHANG set? */
			/* We have children, but they did not exit
			 * or stop yet (we saw no SIGCHLD) */
			return 0;
		}
		/* else: !WNOHANG, waitpid will block, can't short-circuit */
	}
#endif

/* Do we do this right?
 * bash-3.00# sleep 20 | false
 * <ctrl-Z pressed>
 * [3]+  Stopped          sleep 20 | false
 * bash-3.00# echo $?
 * 1   <========== bg pipe is not fully done, but exitcode is already known!
 * [hush 1.14.0: yes we do it right]
 */
	while (1) {
		pid_t childpid;
#if ENABLE_HUSH_FAST
		int i;
		i = G.count_SIGCHLD;
#endif
		childpid = waitpid(-1, &status, attributes);
		if (childpid <= 0) {
			if (childpid && errno != ECHILD)
				bb_perror_msg("waitpid");
#if ENABLE_HUSH_FAST
			else { /* Until next SIGCHLD, waitpid's are useless */
				G.we_have_children = (childpid == 0);
				G.handled_SIGCHLD = i;
//bb_error_msg("[%d] checkjobs: waitpid returned <= 0, G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
			}
#endif
			/* ECHILD (no children), or 0 (no change in children status) */
			rcode = childpid;
			break;
		}
		rcode = process_wait_result(fg_pipe, childpid, status);
		if (rcode >= 0) {
			/* fg_pipe exited or stopped */
			break;
		}
		if (childpid == waitfor_pid) {
			debug_printf_exec("childpid==waitfor_pid:%d status:0x%08x\n", childpid, status);
			rcode = WEXITSTATUS(status);
			if (WIFSIGNALED(status))
				rcode = 128 + WTERMSIG(status);
			if (WIFSTOPPED(status))
				/* bash: "cmd & wait $!" and cmd stops: $? = 128 + stopsig */
				rcode = 128 + WSTOPSIG(status);
			rcode++;
			break; /* "wait PID" called us, give it exitcode+1 */
		}
		/* This wasn't one of our processes, or */
		/* fg_pipe still has running processes, do waitpid again */
	} /* while (waitpid succeeds)... */

	return rcode;
}

#if ENABLE_HUSH_JOB
static int checkjobs_and_fg_shell(struct pipe *fg_pipe)
{
	pid_t p;
	int rcode = checkjobs(fg_pipe, 0 /*(no pid to wait for)*/);
	if (G_saved_tty_pgrp) {
		/* Job finished, move the shell to the foreground */
		p = getpgrp(); /* our process group id */
		debug_printf_jobs("fg'ing ourself: getpgrp()=%d\n", (int)p);
		tcsetpgrp(G_interactive_fd, p);
	}
	return rcode;
}
#endif

/* Start all the jobs, but don't wait for anything to finish.
 * See checkjobs().
 *
 * Return code is normally -1, when the caller has to wait for children
 * to finish to determine the exit status of the pipe.  If the pipe
 * is a simple builtin command, however, the action is done by the
 * time run_pipe returns, and the exit code is provided as the
 * return value.
 *
 * Returns -1 only if started some children. IOW: we have to
 * mask out retvals of builtins etc with 0xff!
 *
 * The only case when we do not need to [v]fork is when the pipe
 * is single, non-backgrounded, non-subshell command. Examples:
 * cmd ; ...   { list } ; ...
 * cmd && ...  { list } && ...
 * cmd || ...  { list } || ...
 * If it is, then we can run cmd as a builtin, NOFORK,
 * or (if SH_STANDALONE) an applet, and we can run the { list }
 * with run_list. If it isn't one of these, we fork and exec cmd.
 *
 * Cases when we must fork:
 * non-single:   cmd | cmd
 * backgrounded: cmd &     { list } &
 * subshell:     ( list ) [&]
 */
#if !ENABLE_HUSH_MODE_X
#define redirect_and_varexp_helper(new_env_p, old_vars_p, command, squirrel, argv_expanded) \
	redirect_and_varexp_helper(new_env_p, old_vars_p, command, squirrel)
#endif
static int redirect_and_varexp_helper(char ***new_env_p,
		struct variable **old_vars_p,
		struct command *command,
		struct squirrel **sqp,
		char **argv_expanded)
{
	/* setup_redirects acts on file descriptors, not FILEs.
	 * This is perfect for work that comes after exec().
	 * Is it really safe for inline use?  Experimentally,
	 * things seem to work. */
	int rcode = setup_redirects(command, sqp);
	if (rcode == 0) {
		char **new_env = expand_assignments(command->argv, command->assignment_cnt);
		*new_env_p = new_env;
		dump_cmd_in_x_mode(new_env);
		dump_cmd_in_x_mode(argv_expanded);
		if (old_vars_p)
			*old_vars_p = set_vars_and_save_old(new_env);
	}
	return rcode;
}
static NOINLINE int run_pipe(struct pipe *pi)
{
	static const char *const null_ptr = NULL;

	int cmd_no;
	int next_infd;
	struct command *command;
	char **argv_expanded;
	char **argv;
	struct squirrel *squirrel = NULL;
	int rcode;

	debug_printf_exec("run_pipe start: members:%d\n", pi->num_cmds);
	debug_enter();

	/* Testcase: set -- q w e; (IFS='' echo "$*"; IFS=''; echo "$*"); echo "$*"
	 * Result should be 3 lines: q w e, qwe, q w e
	 */
	G.ifs = get_local_var_value("IFS");
	if (!G.ifs)
		G.ifs = defifs;

	IF_HUSH_JOB(pi->pgrp = -1;)
	pi->stopped_cmds = 0;
	command = &pi->cmds[0];
	argv_expanded = NULL;

	if (pi->num_cmds != 1
	 || pi->followup == PIPE_BG
	 || command->cmd_type == CMD_SUBSHELL
	) {
		goto must_fork;
	}

	pi->alive_cmds = 1;

	debug_printf_exec(": group:%p argv:'%s'\n",
		command->group, command->argv ? command->argv[0] : "NONE");

	if (command->group) {
#if ENABLE_HUSH_FUNCTIONS
		if (command->cmd_type == CMD_FUNCDEF) {
			/* "executing" func () { list } */
			struct function *funcp;

			funcp = new_function(command->argv[0]);
			/* funcp->name is already set to argv[0] */
			funcp->body = command->group;
# if !BB_MMU
			funcp->body_as_string = command->group_as_string;
			command->group_as_string = NULL;
# endif
			command->group = NULL;
			command->argv[0] = NULL;
			debug_printf_exec("cmd %p has child func at %p\n", command, funcp);
			funcp->parent_cmd = command;
			command->child_func = funcp;

			debug_printf_exec("run_pipe: return EXIT_SUCCESS\n");
			debug_leave();
			return EXIT_SUCCESS;
		}
#endif
		/* { list } */
		debug_printf("non-subshell group\n");
		rcode = 1; /* exitcode if redir failed */
		if (setup_redirects(command, &squirrel) == 0) {
			debug_printf_exec(": run_list\n");
			rcode = run_list(command->group) & 0xff;
		}
		restore_redirects(squirrel);
		IF_HAS_KEYWORDS(if (pi->pi_inverted) rcode = !rcode;)
		debug_leave();
		debug_printf_exec("run_pipe: return %d\n", rcode);
		return rcode;
	}

	argv = command->argv ? command->argv : (char **) &null_ptr;
	{
		const struct built_in_command *x;
#if ENABLE_HUSH_FUNCTIONS
		const struct function *funcp;
#else
		enum { funcp = 0 };
#endif
		char **new_env = NULL;
		struct variable *old_vars = NULL;

		if (argv[command->assignment_cnt] == NULL) {
			/* Assignments, but no command */
			/* Ensure redirects take effect (that is, create files).
			 * Try "a=t >file" */
#if 0 /* A few cases in testsuite fail with this code. FIXME */
			rcode = redirect_and_varexp_helper(&new_env, /*old_vars:*/ NULL, command, &squirrel, /*argv_expanded:*/ NULL);
			/* Set shell variables */
			if (new_env) {
				argv = new_env;
				while (*argv) {
					if (set_local_var(*argv, /*flag:*/ 0)) {
						/* assignment to readonly var / putenv error? */
						rcode = 1;
					}
					argv++;
				}
			}
			/* Redirect error sets $? to 1. Otherwise,
			 * if evaluating assignment value set $?, retain it.
			 * Try "false; q=`exit 2`; echo $?" - should print 2: */
			if (rcode == 0)
				rcode = G.last_exitcode;
			/* Exit, _skipping_ variable restoring code: */
			goto clean_up_and_ret0;

#else /* Older, bigger, but more correct code */

			rcode = setup_redirects(command, &squirrel);
			restore_redirects(squirrel);
			/* Set shell variables */
			if (G_x_mode)
				bb_putchar_stderr('+');
			while (*argv) {
				char *p = expand_string_to_string(*argv, /*unbackslash:*/ 1);
				if (G_x_mode)
					fprintf(stderr, " %s", p);
				debug_printf_exec("set shell var:'%s'->'%s'\n",
						*argv, p);
				if (set_local_var(p, /*flag:*/ 0)) {
					/* assignment to readonly var / putenv error? */
					rcode = 1;
				}
				argv++;
			}
			if (G_x_mode)
				bb_putchar_stderr('\n');
			/* Redirect error sets $? to 1. Otherwise,
			 * if evaluating assignment value set $?, retain it.
			 * Try "false; q=`exit 2`; echo $?" - should print 2: */
			if (rcode == 0)
				rcode = G.last_exitcode;
			IF_HAS_KEYWORDS(if (pi->pi_inverted) rcode = !rcode;)
			debug_leave();
			debug_printf_exec("run_pipe: return %d\n", rcode);
			return rcode;
#endif
		}

		/* Expand the rest into (possibly) many strings each */
#if BASH_TEST2
		if (command->cmd_type == CMD_SINGLEWORD_NOGLOB) {
			argv_expanded = expand_strvec_to_strvec_singleword_noglob(argv + command->assignment_cnt);
		} else
#endif
		{
			argv_expanded = expand_strvec_to_strvec(argv + command->assignment_cnt);
		}

		/* if someone gives us an empty string: `cmd with empty output` */
		if (!argv_expanded[0]) {
			free(argv_expanded);
			debug_leave();
			return G.last_exitcode;
		}

#if ENABLE_HUSH_FUNCTIONS
		/* Check if argv[0] matches any functions (this goes before bltins) */
		funcp = find_function(argv_expanded[0]);
#endif
		x = NULL;
		if (!funcp)
			x = find_builtin(argv_expanded[0]);
		if (x || funcp) {
			if (!funcp) {
				if (x->b_function == builtin_exec && argv_expanded[1] == NULL) {
					debug_printf("exec with redirects only\n");
					rcode = setup_redirects(command, NULL);
					/* rcode=1 can be if redir file can't be opened */
					goto clean_up_and_ret1;
				}
			}
			rcode = redirect_and_varexp_helper(&new_env, &old_vars, command, &squirrel, argv_expanded);
			if (rcode == 0) {
				if (!funcp) {
					debug_printf_exec(": builtin '%s' '%s'...\n",
						x->b_cmd, argv_expanded[1]);
					fflush_all();
					rcode = x->b_function(argv_expanded) & 0xff;
					fflush_all();
				}
#if ENABLE_HUSH_FUNCTIONS
				else {
# if ENABLE_HUSH_LOCAL
					struct variable **sv;
					sv = G.shadowed_vars_pp;
					G.shadowed_vars_pp = &old_vars;
# endif
					debug_printf_exec(": function '%s' '%s'...\n",
						funcp->name, argv_expanded[1]);
					rcode = run_function(funcp, argv_expanded) & 0xff;
# if ENABLE_HUSH_LOCAL
					G.shadowed_vars_pp = sv;
# endif
				}
#endif
			}
 clean_up_and_ret:
			unset_vars(new_env);
			add_vars(old_vars);
/* clean_up_and_ret0: */
			restore_redirects(squirrel);
			/*
			 * Try "usleep 99999999" + ^C + "echo $?"
			 * with FEATURE_SH_NOFORK=y.
			 */
			if (!funcp) {
				/* It was builtin or nofork.
				 * if this would be a real fork/execed program,
				 * it should have died if a fatal sig was received.
				 * But OTOH, there was no separate process,
				 * the sig was sent to _shell_, not to non-existing
				 * child.
				 * Let's just handle ^C only, this one is obvious:
				 * we aren't ok with exitcode 0 when ^C was pressed
				 * during builtin/nofork.
				 */
				if (sigismember(&G.pending_set, SIGINT))
					rcode = 128 + SIGINT;
			}
 clean_up_and_ret1:
			free(argv_expanded);
			IF_HAS_KEYWORDS(if (pi->pi_inverted) rcode = !rcode;)
			debug_leave();
			debug_printf_exec("run_pipe return %d\n", rcode);
			return rcode;
		}

		if (ENABLE_FEATURE_SH_NOFORK) {
			int n = find_applet_by_name(argv_expanded[0]);
			if (n >= 0 && APPLET_IS_NOFORK(n)) {
				rcode = redirect_and_varexp_helper(&new_env, &old_vars, command, &squirrel, argv_expanded);
				if (rcode == 0) {
					debug_printf_exec(": run_nofork_applet '%s' '%s'...\n",
						argv_expanded[0], argv_expanded[1]);
					/*
					 * Note: signals (^C) can't interrupt here.
					 * We remember them and they will be acted upon
					 * after applet returns.
					 * This makes applets which can run for a long time
					 * and/or wait for user input ineligible for NOFORK:
					 * for example, "yes" or "rm" (rm -i waits for input).
					 */
					rcode = run_nofork_applet(n, argv_expanded);
				}
				goto clean_up_and_ret;
			}
		}
		/* It is neither builtin nor applet. We must fork. */
	}

 must_fork:
	/* NB: argv_expanded may already be created, and that
	 * might include `cmd` runs! Do not rerun it! We *must*
	 * use argv_expanded if it's non-NULL */

	/* Going to fork a child per each pipe member */
	pi->alive_cmds = 0;
	next_infd = 0;

	cmd_no = 0;
	while (cmd_no < pi->num_cmds) {
		struct fd_pair pipefds;
#if !BB_MMU
		volatile nommu_save_t nommu_save;
		nommu_save.new_env = NULL;
		nommu_save.old_vars = NULL;
		nommu_save.argv = NULL;
		nommu_save.argv_from_re_execing = NULL;
#endif
		command = &pi->cmds[cmd_no];
		cmd_no++;
		if (command->argv) {
			debug_printf_exec(": pipe member '%s' '%s'...\n",
					command->argv[0], command->argv[1]);
		} else {
			debug_printf_exec(": pipe member with no argv\n");
		}

		/* pipes are inserted between pairs of commands */
		pipefds.rd = 0;
		pipefds.wr = 1;
		if (cmd_no < pi->num_cmds)
			xpiped_pair(pipefds);

		command->pid = BB_MMU ? fork() : vfork();
		if (!command->pid) { /* child */
#if ENABLE_HUSH_JOB
			disable_restore_tty_pgrp_on_exit();
			CLEAR_RANDOM_T(&G.random_gen); /* or else $RANDOM repeats in child */

			/* Every child adds itself to new process group
			 * with pgid == pid_of_first_child_in_pipe */
			if (G.run_list_level == 1 && G_interactive_fd) {
				pid_t pgrp;
				pgrp = pi->pgrp;
				if (pgrp < 0) /* true for 1st process only */
					pgrp = getpid();
				if (setpgid(0, pgrp) == 0
				 && pi->followup != PIPE_BG
				 && G_saved_tty_pgrp /* we have ctty */
				) {
					/* We do it in *every* child, not just first,
					 * to avoid races */
					tcsetpgrp(G_interactive_fd, pgrp);
				}
			}
#endif
			if (pi->alive_cmds == 0 && pi->followup == PIPE_BG) {
				/* 1st cmd in backgrounded pipe
				 * should have its stdin /dev/null'ed */
				close(0);
				if (open(bb_dev_null, O_RDONLY))
					xopen("/", O_RDONLY);
			} else {
				xmove_fd(next_infd, 0);
			}
			xmove_fd(pipefds.wr, 1);
			if (pipefds.rd > 1)
				close(pipefds.rd);
			/* Like bash, explicit redirects override pipes,
			 * and the pipe fd (fd#1) is available for dup'ing:
			 * "cmd1 2>&1 | cmd2": fd#1 is duped to fd#2, thus stderr
			 * of cmd1 goes into pipe.
			 */
			if (setup_redirects(command, NULL)) {
				/* Happens when redir file can't be opened:
				 * $ hush -c 'echo FOO >&2 | echo BAR 3>/qwe/rty; echo BAZ'
				 * FOO
				 * hush: can't open '/qwe/rty': No such file or directory
				 * BAZ
				 * (echo BAR is not executed, it hits _exit(1) below)
				 */
				_exit(1);
			}

			/* Stores to nommu_save list of env vars putenv'ed
			 * (NOMMU, on MMU we don't need that) */
			/* cast away volatility... */
			pseudo_exec((nommu_save_t*) &nommu_save, command, argv_expanded);
			/* pseudo_exec() does not return */
		}

		/* parent or error */
#if ENABLE_HUSH_FAST
		G.count_SIGCHLD++;
//bb_error_msg("[%d] fork in run_pipe: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
#endif
		enable_restore_tty_pgrp_on_exit();
#if !BB_MMU
		/* Clean up after vforked child */
		free(nommu_save.argv);
		free(nommu_save.argv_from_re_execing);
		unset_vars(nommu_save.new_env);
		add_vars(nommu_save.old_vars);
#endif
		free(argv_expanded);
		argv_expanded = NULL;
		if (command->pid < 0) { /* [v]fork failed */
			/* Clearly indicate, was it fork or vfork */
			bb_perror_msg(BB_MMU ? "vfork"+1 : "vfork");
		} else {
			pi->alive_cmds++;
#if ENABLE_HUSH_JOB
			/* Second and next children need to know pid of first one */
			if (pi->pgrp < 0)
				pi->pgrp = command->pid;
#endif
		}

		if (cmd_no > 1)
			close(next_infd);
		if (cmd_no < pi->num_cmds)
			close(pipefds.wr);
		/* Pass read (output) pipe end to next iteration */
		next_infd = pipefds.rd;
	}

	if (!pi->alive_cmds) {
		debug_leave();
		debug_printf_exec("run_pipe return 1 (all forks failed, no children)\n");
		return 1;
	}

	debug_leave();
	debug_printf_exec("run_pipe return -1 (%u children started)\n", pi->alive_cmds);
	return -1;
}

/* NB: called by pseudo_exec, and therefore must not modify any
 * global data until exec/_exit (we can be a child after vfork!) */
static int run_list(struct pipe *pi)
{
#if ENABLE_HUSH_CASE
	char *case_word = NULL;
#endif
#if ENABLE_HUSH_LOOPS
	struct pipe *loop_top = NULL;
	char **for_lcur = NULL;
	char **for_list = NULL;
#endif
	smallint last_followup;
	smalluint rcode;
#if ENABLE_HUSH_IF || ENABLE_HUSH_CASE
	smalluint cond_code = 0;
#else
	enum { cond_code = 0 };
#endif
#if HAS_KEYWORDS
	smallint rword;      /* RES_foo */
	smallint last_rword; /* ditto */
#endif

	debug_printf_exec("run_list start lvl %d\n", G.run_list_level);
	debug_enter();

#if ENABLE_HUSH_LOOPS
	/* Check syntax for "for" */
	{
		struct pipe *cpipe;
		for (cpipe = pi; cpipe; cpipe = cpipe->next) {
			if (cpipe->res_word != RES_FOR && cpipe->res_word != RES_IN)
				continue;
			/* current word is FOR or IN (BOLD in comments below) */
			if (cpipe->next == NULL) {
				syntax_error("malformed for");
				debug_leave();
				debug_printf_exec("run_list lvl %d return 1\n", G.run_list_level);
				return 1;
			}
			/* "FOR v; do ..." and "for v IN a b; do..." are ok */
			if (cpipe->next->res_word == RES_DO)
				continue;
			/* next word is not "do". It must be "in" then ("FOR v in ...") */
			if (cpipe->res_word == RES_IN /* "for v IN a b; not_do..."? */
			 || cpipe->next->res_word != RES_IN /* FOR v not_do_and_not_in..."? */
			) {
				syntax_error("malformed for");
				debug_leave();
				debug_printf_exec("run_list lvl %d return 1\n", G.run_list_level);
				return 1;
			}
		}
	}
#endif

	/* Past this point, all code paths should jump to ret: label
	 * in order to return, no direct "return" statements please.
	 * This helps to ensure that no memory is leaked. */

#if ENABLE_HUSH_JOB
	G.run_list_level++;
#endif

#if HAS_KEYWORDS
	rword = RES_NONE;
	last_rword = RES_XXXX;
#endif
	last_followup = PIPE_SEQ;
	rcode = G.last_exitcode;

	/* Go through list of pipes, (maybe) executing them. */
	for (; pi; pi = IF_HUSH_LOOPS(rword == RES_DONE ? loop_top : ) pi->next) {
		int r;
		int sv_errexit_depth;

		if (G.flag_SIGINT)
			break;
		if (G_flag_return_in_progress == 1)
			break;

		IF_HAS_KEYWORDS(rword = pi->res_word;)
		debug_printf_exec(": rword=%d cond_code=%d last_rword=%d\n",
				rword, cond_code, last_rword);

		sv_errexit_depth = G.errexit_depth;
		if (IF_HAS_KEYWORDS(rword == RES_IF || rword == RES_ELIF ||)
		    pi->followup != PIPE_SEQ
		) {
			G.errexit_depth++;
		}
#if ENABLE_HUSH_LOOPS
		if ((rword == RES_WHILE || rword == RES_UNTIL || rword == RES_FOR)
		 && loop_top == NULL /* avoid bumping G.depth_of_loop twice */
		) {
			/* start of a loop: remember where loop starts */
			loop_top = pi;
			G.depth_of_loop++;
		}
#endif
		/* Still in the same "if...", "then..." or "do..." branch? */
		if (IF_HAS_KEYWORDS(rword == last_rword &&) 1) {
			if ((rcode == 0 && last_followup == PIPE_OR)
			 || (rcode != 0 && last_followup == PIPE_AND)
			) {
				/* It is "<true> || CMD" or "<false> && CMD"
				 * and we should not execute CMD */
				debug_printf_exec("skipped cmd because of || or &&\n");
				last_followup = pi->followup;
				goto dont_check_jobs_but_continue;
			}
		}
		last_followup = pi->followup;
		IF_HAS_KEYWORDS(last_rword = rword;)
#if ENABLE_HUSH_IF
		if (cond_code) {
			if (rword == RES_THEN) {
				/* if false; then ... fi has exitcode 0! */
				G.last_exitcode = rcode = EXIT_SUCCESS;
				/* "if <false> THEN cmd": skip cmd */
				continue;
			}
		} else {
			if (rword == RES_ELSE || rword == RES_ELIF) {
				/* "if <true> then ... ELSE/ELIF cmd":
				 * skip cmd and all following ones */
				break;
			}
		}
#endif
#if ENABLE_HUSH_LOOPS
		if (rword == RES_FOR) { /* && pi->num_cmds - always == 1 */
			if (!for_lcur) {
				/* first loop through for */

				static const char encoded_dollar_at[] ALIGN1 = {
					SPECIAL_VAR_SYMBOL, '@' | 0x80, SPECIAL_VAR_SYMBOL, '\0'
				}; /* encoded representation of "$@" */
				static const char *const encoded_dollar_at_argv[] = {
					encoded_dollar_at, NULL
				}; /* argv list with one element: "$@" */
				char **vals;

				vals = (char**)encoded_dollar_at_argv;
				if (pi->next->res_word == RES_IN) {
					/* if no variable values after "in" we skip "for" */
					if (!pi->next->cmds[0].argv) {
						G.last_exitcode = rcode = EXIT_SUCCESS;
						debug_printf_exec(": null FOR: exitcode EXIT_SUCCESS\n");
						break;
					}
					vals = pi->next->cmds[0].argv;
				} /* else: "for var; do..." -> assume "$@" list */
				/* create list of variable values */
				debug_print_strings("for_list made from", vals);
				for_list = expand_strvec_to_strvec(vals);
				for_lcur = for_list;
				debug_print_strings("for_list", for_list);
			}
			if (!*for_lcur) {
				/* "for" loop is over, clean up */
				free(for_list);
				for_list = NULL;
				for_lcur = NULL;
				break;
			}
			/* Insert next value from for_lcur */
			/* note: *for_lcur already has quotes removed, $var expanded, etc */
			set_local_var(xasprintf("%s=%s", pi->cmds[0].argv[0], *for_lcur++), /*flag:*/ 0);
			continue;
		}
		if (rword == RES_IN) {
			continue; /* "for v IN list;..." - "in" has no cmds anyway */
		}
		if (rword == RES_DONE) {
			continue; /* "done" has no cmds too */
		}
#endif
#if ENABLE_HUSH_CASE
		if (rword == RES_CASE) {
			debug_printf_exec("CASE cond_code:%d\n", cond_code);
			case_word = expand_strvec_to_string(pi->cmds->argv);
			unbackslash(case_word);
			continue;
		}
		if (rword == RES_MATCH) {
			char **argv;

			debug_printf_exec("MATCH cond_code:%d\n", cond_code);
			if (!case_word) /* "case ... matched_word) ... WORD)": we executed selected branch, stop */
				break;
			/* all prev words didn't match, does this one match? */
			argv = pi->cmds->argv;
			while (*argv) {
				char *pattern = expand_string_to_string(*argv, /*unbackslash:*/ 0);
				/* TODO: which FNM_xxx flags to use? */
				cond_code = (fnmatch(pattern, case_word, /*flags:*/ 0) != 0);
				debug_printf_exec("fnmatch(pattern:'%s',str:'%s'):%d\n", pattern, case_word, cond_code);
				free(pattern);
				if (cond_code == 0) { /* match! we will execute this branch */
					free(case_word);
					case_word = NULL; /* make future "word)" stop */
					break;
				}
				argv++;
			}
			continue;
		}
		if (rword == RES_CASE_BODY) { /* inside of a case branch */
			debug_printf_exec("CASE_BODY cond_code:%d\n", cond_code);
			if (cond_code != 0)
				continue; /* not matched yet, skip this pipe */
		}
		if (rword == RES_ESAC) {
			debug_printf_exec("ESAC cond_code:%d\n", cond_code);
			if (case_word) {
				/* "case" did not match anything: still set $? (to 0) */
				G.last_exitcode = rcode = EXIT_SUCCESS;
			}
		}
#endif
		/* Just pressing <enter> in shell should check for jobs.
		 * OTOH, in non-interactive shell this is useless
		 * and only leads to extra job checks */
		if (pi->num_cmds == 0) {
			if (G_interactive_fd)
				goto check_jobs_and_continue;
			continue;
		}

		/* After analyzing all keywords and conditions, we decided
		 * to execute this pipe. NB: have to do checkjobs(NULL)
		 * after run_pipe to collect any background children,
		 * even if list execution is to be stopped. */
		debug_printf_exec(": run_pipe with %d members\n", pi->num_cmds);
#if ENABLE_HUSH_LOOPS
		G.flag_break_continue = 0;
#endif
		rcode = r = run_pipe(pi); /* NB: rcode is a smalluint, r is int */
		if (r != -1) {
			/* We ran a builtin, function, or group.
			 * rcode is already known
			 * and we don't need to wait for anything. */
			debug_printf_exec(": builtin/func exitcode %d\n", rcode);
			G.last_exitcode = rcode;
			check_and_run_traps();
#if ENABLE_HUSH_LOOPS
			/* Was it "break" or "continue"? */
			if (G.flag_break_continue) {
				smallint fbc = G.flag_break_continue;
				/* We might fall into outer *loop*,
				 * don't want to break it too */
				if (loop_top) {
					G.depth_break_continue--;
					if (G.depth_break_continue == 0)
						G.flag_break_continue = 0;
					/* else: e.g. "continue 2" should *break* once, *then* continue */
				} /* else: "while... do... { we are here (innermost list is not a loop!) };...done" */
				if (G.depth_break_continue != 0 || fbc == BC_BREAK) {
					checkjobs(NULL, 0 /*(no pid to wait for)*/);
					break;
				}
				/* "continue": simulate end of loop */
				rword = RES_DONE;
				continue;
			}
#endif
			if (G_flag_return_in_progress == 1) {
				checkjobs(NULL, 0 /*(no pid to wait for)*/);
				break;
			}
		} else if (pi->followup == PIPE_BG) {
			/* What does bash do with attempts to background builtins? */
			/* even bash 3.2 doesn't do that well with nested bg:
			 * try "{ { sleep 10; echo DEEP; } & echo HERE; } &".
			 * I'm NOT treating inner &'s as jobs */
#if ENABLE_HUSH_JOB
			if (G.run_list_level == 1)
				insert_job_into_table(pi);
#endif
			/* Last command's pid goes to $! */
			G.last_bg_pid = pi->cmds[pi->num_cmds - 1].pid;
			G.last_bg_pid_exitcode = 0;
			debug_printf_exec(": cmd&: exitcode EXIT_SUCCESS\n");
/* Check pi->pi_inverted? "! sleep 1 & echo $?": bash says 1. dash and ash say 0 */
			rcode = EXIT_SUCCESS;
			goto check_traps;
		} else {
#if ENABLE_HUSH_JOB
			if (G.run_list_level == 1 && G_interactive_fd) {
				/* Waits for completion, then fg's main shell */
				rcode = checkjobs_and_fg_shell(pi);
				debug_printf_exec(": checkjobs_and_fg_shell exitcode %d\n", rcode);
				goto check_traps;
			}
#endif
			/* This one just waits for completion */
			rcode = checkjobs(pi, 0 /*(no pid to wait for)*/);
			debug_printf_exec(": checkjobs exitcode %d\n", rcode);
 check_traps:
			G.last_exitcode = rcode;
			check_and_run_traps();
		}

		/* Handle "set -e" */
		if (rcode != 0 && G.o_opt[OPT_O_ERREXIT]) {
			debug_printf_exec("ERREXIT:1 errexit_depth:%d\n", G.errexit_depth);
			if (G.errexit_depth == 0)
				hush_exit(rcode);
		}
		G.errexit_depth = sv_errexit_depth;

		/* Analyze how result affects subsequent commands */
#if ENABLE_HUSH_IF
		if (rword == RES_IF || rword == RES_ELIF)
			cond_code = rcode;
#endif
 check_jobs_and_continue:
		checkjobs(NULL, 0 /*(no pid to wait for)*/);
 dont_check_jobs_but_continue: ;
#if ENABLE_HUSH_LOOPS
		/* Beware of "while false; true; do ..."! */
		if (pi->next
		 && (pi->next->res_word == RES_DO || pi->next->res_word == RES_DONE)
		 /* check for RES_DONE is needed for "while ...; do \n done" case */
		) {
			if (rword == RES_WHILE) {
				if (rcode) {
					/* "while false; do...done" - exitcode 0 */
					G.last_exitcode = rcode = EXIT_SUCCESS;
					debug_printf_exec(": while expr is false: breaking (exitcode:EXIT_SUCCESS)\n");
					break;
				}
			}
			if (rword == RES_UNTIL) {
				if (!rcode) {
					debug_printf_exec(": until expr is true: breaking\n");
					break;
				}
			}
		}
#endif
	} /* for (pi) */

#if ENABLE_HUSH_JOB
	G.run_list_level--;
#endif
#if ENABLE_HUSH_LOOPS
	if (loop_top)
		G.depth_of_loop--;
	free(for_list);
#endif
#if ENABLE_HUSH_CASE
	free(case_word);
#endif
	debug_leave();
	debug_printf_exec("run_list lvl %d return %d\n", G.run_list_level + 1, rcode);
	return rcode;
}

/* Select which version we will use */
static int run_and_free_list(struct pipe *pi)
{
	int rcode = 0;
	debug_printf_exec("run_and_free_list entered\n");
	if (!G.o_opt[OPT_O_NOEXEC]) {
		debug_printf_exec(": run_list: 1st pipe with %d cmds\n", pi->num_cmds);
		rcode = run_list(pi);
	}
	/* free_pipe_list has the side effect of clearing memory.
	 * In the long run that function can be merged with run_list,
	 * but doing that now would hobble the debugging effort. */
	free_pipe_list(pi);
	debug_printf_exec("run_and_free_list return %d\n", rcode);
	return rcode;
}


static void install_sighandlers(unsigned mask)
{
	sighandler_t old_handler;
	unsigned sig = 0;
	while ((mask >>= 1) != 0) {
		sig++;
		if (!(mask & 1))
			continue;
		old_handler = install_sighandler(sig, pick_sighandler(sig));
		/* POSIX allows shell to re-enable SIGCHLD
		 * even if it was SIG_IGN on entry.
		 * Therefore we skip IGN check for it:
		 */
		if (sig == SIGCHLD)
			continue;
		/* bash re-enables SIGHUP which is SIG_IGNed on entry.
		 * Try: "trap '' HUP; bash; echo RET" and type "kill -HUP $$"
		 */
		//if (sig == SIGHUP) continue; - TODO?
		if (old_handler == SIG_IGN) {
			/* oops... restore back to IGN, and record this fact */
			install_sighandler(sig, old_handler);
#if ENABLE_HUSH_TRAP
			if (!G_traps)
				G_traps = xzalloc(sizeof(G_traps[0]) * NSIG);
			free(G_traps[sig]);
			G_traps[sig] = xzalloc(1); /* == xstrdup(""); */
#endif
		}
	}
}

/* Called a few times only (or even once if "sh -c") */
static void install_special_sighandlers(void)
{
	unsigned mask;

	/* Which signals are shell-special? */
	mask = (1 << SIGQUIT) | (1 << SIGCHLD);
	if (G_interactive_fd) {
		mask |= SPECIAL_INTERACTIVE_SIGS;
		if (G_saved_tty_pgrp) /* we have ctty, job control sigs work */
			mask |= SPECIAL_JOBSTOP_SIGS;
	}
	/* Careful, do not re-install handlers we already installed */
	if (G.special_sig_mask != mask) {
		unsigned diff = mask & ~G.special_sig_mask;
		G.special_sig_mask = mask;
		install_sighandlers(diff);
	}
}

#if ENABLE_HUSH_JOB
/* helper */
/* Set handlers to restore tty pgrp and exit */
static void install_fatal_sighandlers(void)
{
	unsigned mask;

	/* We will restore tty pgrp on these signals */
	mask = 0
		/*+ (1 << SIGILL ) * HUSH_DEBUG*/
		/*+ (1 << SIGFPE ) * HUSH_DEBUG*/
		+ (1 << SIGBUS ) * HUSH_DEBUG
		+ (1 << SIGSEGV) * HUSH_DEBUG
		/*+ (1 << SIGTRAP) * HUSH_DEBUG*/
		+ (1 << SIGABRT)
	/* bash 3.2 seems to handle these just like 'fatal' ones */
		+ (1 << SIGPIPE)
		+ (1 << SIGALRM)
	/* if we are interactive, SIGHUP, SIGTERM and SIGINT are special sigs.
	 * if we aren't interactive... but in this case
	 * we never want to restore pgrp on exit, and this fn is not called
	 */
		/*+ (1 << SIGHUP )*/
		/*+ (1 << SIGTERM)*/
		/*+ (1 << SIGINT )*/
	;
	G_fatal_sig_mask = mask;

	install_sighandlers(mask);
}
#endif

static int set_mode(int state, char mode, const char *o_opt)
{
	int idx;
	switch (mode) {
	case 'n':
		G.o_opt[OPT_O_NOEXEC] = state;
		break;
	case 'x':
		IF_HUSH_MODE_X(G_x_mode = state;)
		break;
	case 'o':
		if (!o_opt) {
			/* "set -+o" without parameter.
			 * in bash, set -o produces this output:
			 *  pipefail        off
			 * and set +o:
			 *  set +o pipefail
			 * We always use the second form.
			 */
			const char *p = o_opt_strings;
			idx = 0;
			while (*p) {
				printf("set %co %s\n", (G.o_opt[idx] ? '-' : '+'), p);
				idx++;
				p += strlen(p) + 1;
			}
			break;
		}
		idx = index_in_strings(o_opt_strings, o_opt);
		if (idx >= 0) {
			G.o_opt[idx] = state;
			break;
		}
	case 'e':
		G.o_opt[OPT_O_ERREXIT] = state;
		break;
	default:
		return EXIT_FAILURE;
	}
	return EXIT_SUCCESS;
}

int hush_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int hush_main(int argc, char **argv)
{
	enum {
		OPT_login = (1 << 0),
	};
	unsigned flags;
	int opt;
	unsigned builtin_argc;
	char **e;
	struct variable *cur_var;
	struct variable *shell_ver;

	INIT_G();
	if (EXIT_SUCCESS != 0) /* if EXIT_SUCCESS == 0, it is already done */
		G.last_exitcode = EXIT_SUCCESS;

#if ENABLE_HUSH_FAST
	G.count_SIGCHLD++; /* ensure it is != G.handled_SIGCHLD */
#endif
#if !BB_MMU
	G.argv0_for_re_execing = argv[0];
#endif
	/* Deal with HUSH_VERSION */
	shell_ver = xzalloc(sizeof(*shell_ver));
	shell_ver->flg_export = 1;
	shell_ver->flg_read_only = 1;
	/* Code which handles ${var<op>...} needs writable values for all variables,
	 * therefore we xstrdup: */
	shell_ver->varstr = xstrdup(hush_version_str);
	/* Create shell local variables from the values
	 * currently living in the environment */
	debug_printf_env("unsetenv '%s'\n", "HUSH_VERSION");
	unsetenv("HUSH_VERSION"); /* in case it exists in initial env */
	G.top_var = shell_ver;
	cur_var = G.top_var;
	e = environ;
	if (e) while (*e) {
		char *value = strchr(*e, '=');
		if (value) { /* paranoia */
			cur_var->next = xzalloc(sizeof(*cur_var));
			cur_var = cur_var->next;
			cur_var->varstr = *e;
			cur_var->max_len = strlen(*e);
			cur_var->flg_export = 1;
		}
		e++;
	}
	/* (Re)insert HUSH_VERSION into env (AFTER we scanned the env!) */
	debug_printf_env("putenv '%s'\n", shell_ver->varstr);
	putenv(shell_ver->varstr);

	/* Export PWD */
	set_pwd_var(SETFLAG_EXPORT);

#if BASH_HOSTNAME_VAR
	/* Set (but not export) HOSTNAME unless already set */
	if (!get_local_var_value("HOSTNAME")) {
		struct utsname uts;
		uname(&uts);
		set_local_var_from_halves("HOSTNAME", uts.nodename);
	}
	/* bash also exports SHLVL and _,
	 * and sets (but doesn't export) the following variables:
	 * BASH=/bin/bash
	 * BASH_VERSINFO=([0]="3" [1]="2" [2]="0" [3]="1" [4]="release" [5]="i386-pc-linux-gnu")
	 * BASH_VERSION='3.2.0(1)-release'
	 * HOSTTYPE=i386
	 * MACHTYPE=i386-pc-linux-gnu
	 * OSTYPE=linux-gnu
	 * PPID=<NNNNN> - we also do it elsewhere
	 * EUID=<NNNNN>
	 * UID=<NNNNN>
	 * GROUPS=()
	 * LINES=<NNN>
	 * COLUMNS=<NNN>
	 * BASH_ARGC=()
	 * BASH_ARGV=()
	 * BASH_LINENO=()
	 * BASH_SOURCE=()
	 * DIRSTACK=()
	 * PIPESTATUS=([0]="0")
	 * HISTFILE=/<xxx>/.bash_history
	 * HISTFILESIZE=500
	 * HISTSIZE=500
	 * MAILCHECK=60
	 * PATH=/usr/gnu/bin:/usr/local/bin:/bin:/usr/bin:.
	 * SHELL=/bin/bash
	 * SHELLOPTS=braceexpand:emacs:hashall:histexpand:history:interactive-comments:monitor
	 * TERM=dumb
	 * OPTERR=1
	 * OPTIND=1
	 * IFS=$' \t\n'
	 * PS1='\s-\v\$ '
	 * PS2='> '
	 * PS4='+ '
	 */
#endif

#if ENABLE_FEATURE_EDITING
	G.line_input_state = new_line_input_t(FOR_SHELL);
#endif

	/* Initialize some more globals to non-zero values */
	cmdedit_update_prompt();

	die_func = restore_ttypgrp_and__exit;

	/* Shell is non-interactive at first. We need to call
	 * install_special_sighandlers() if we are going to execute "sh <script>",
	 * "sh -c <cmds>" or login shell's /etc/profile and friends.
	 * If we later decide that we are interactive, we run install_special_sighandlers()
	 * in order to intercept (more) signals.
	 */

	/* Parse options */
	/* http://www.opengroup.org/onlinepubs/9699919799/utilities/sh.html */
	flags = (argv[0] && argv[0][0] == '-') ? OPT_login : 0;
	builtin_argc = 0;
	while (1) {
		opt = getopt(argc, argv, "+c:exinsl"
#if !BB_MMU
				"<:$:R:V:"
# if ENABLE_HUSH_FUNCTIONS
				"F:"
# endif
#endif
		);
		if (opt <= 0)
			break;
		switch (opt) {
		case 'c':
			/* Possibilities:
			 * sh ... -c 'script'
			 * sh ... -c 'script' ARG0 [ARG1...]
			 * On NOMMU, if builtin_argc != 0,
			 * sh ... -c 'builtin' BARGV... "" ARG0 [ARG1...]
			 * "" needs to be replaced with NULL
			 * and BARGV vector fed to builtin function.
			 * Note: the form without ARG0 never happens:
			 * sh ... -c 'builtin' BARGV... ""
			 */
			if (!G.root_pid) {
				G.root_pid = getpid();
				G.root_ppid = getppid();
			}
			G.global_argv = argv + optind;
			G.global_argc = argc - optind;
			if (builtin_argc) {
				/* -c 'builtin' [BARGV...] "" ARG0 [ARG1...] */
				const struct built_in_command *x;

				install_special_sighandlers();
				x = find_builtin(optarg);
				if (x) { /* paranoia */
					G.global_argc -= builtin_argc; /* skip [BARGV...] "" */
					G.global_argv += builtin_argc;
					G.global_argv[-1] = NULL; /* replace "" */
					fflush_all();
					G.last_exitcode = x->b_function(argv + optind - 1);
				}
				goto final_return;
			}
			if (!G.global_argv[0]) {
				/* -c 'script' (no params): prevent empty $0 */
				G.global_argv--; /* points to argv[i] of 'script' */
				G.global_argv[0] = argv[0];
				G.global_argc++;
			} /* else -c 'script' ARG0 [ARG1...]: $0 is ARG0 */
			install_special_sighandlers();
			parse_and_run_string(optarg);
			goto final_return;
		case 'i':
			/* Well, we cannot just declare interactiveness,
			 * we have to have some stuff (ctty, etc) */
			/* G_interactive_fd++; */
			break;
		case 's':
			/* "-s" means "read from stdin", but this is how we always
			 * operate, so simply do nothing here. */
			break;
		case 'l':
			flags |= OPT_login;
			break;
#if !BB_MMU
		case '<': /* "big heredoc" support */
			full_write1_str(optarg);
			_exit(0);
		case '$': {
			unsigned long long empty_trap_mask;

			G.root_pid = bb_strtou(optarg, &optarg, 16);
			optarg++;
			G.root_ppid = bb_strtou(optarg, &optarg, 16);
			optarg++;
			G.last_bg_pid = bb_strtou(optarg, &optarg, 16);
			optarg++;
			G.last_exitcode = bb_strtou(optarg, &optarg, 16);
			optarg++;
			builtin_argc = bb_strtou(optarg, &optarg, 16);
			optarg++;
			empty_trap_mask = bb_strtoull(optarg, &optarg, 16);
			if (empty_trap_mask != 0) {
				IF_HUSH_TRAP(int sig;)
				install_special_sighandlers();
# if ENABLE_HUSH_TRAP
				G_traps = xzalloc(sizeof(G_traps[0]) * NSIG);
				for (sig = 1; sig < NSIG; sig++) {
					if (empty_trap_mask & (1LL << sig)) {
						G_traps[sig] = xzalloc(1); /* == xstrdup(""); */
						install_sighandler(sig, SIG_IGN);
					}
				}
# endif
			}
# if ENABLE_HUSH_LOOPS
			optarg++;
			G.depth_of_loop = bb_strtou(optarg, &optarg, 16);
# endif
			break;
		}
		case 'R':
		case 'V':
			set_local_var(xstrdup(optarg), opt == 'R' ? SETFLAG_MAKE_RO : 0);
			break;
# if ENABLE_HUSH_FUNCTIONS
		case 'F': {
			struct function *funcp = new_function(optarg);
			/* funcp->name is already set to optarg */
			/* funcp->body is set to NULL. It's a special case. */
			funcp->body_as_string = argv[optind];
			optind++;
			break;
		}
# endif
#endif
		case 'n':
		case 'x':
		case 'e':
			if (set_mode(1, opt, NULL) == 0) /* no error */
				break;
		default:
#ifndef BB_VER
			fprintf(stderr, "Usage: sh [FILE]...\n"
					"   or: sh -c command [args]...\n\n");
			exit(EXIT_FAILURE);
#else
			bb_show_usage();
#endif
		}
	} /* option parsing loop */

	/* Skip options. Try "hush -l": $1 should not be "-l"! */
	G.global_argc = argc - (optind - 1);
	G.global_argv = argv + (optind - 1);
	G.global_argv[0] = argv[0];

	if (!G.root_pid) {
		G.root_pid = getpid();
		G.root_ppid = getppid();
	}

	/* If we are login shell... */
	if (flags & OPT_login) {
		FILE *input;
		debug_printf("sourcing /etc/profile\n");
		input = fopen_for_read("/etc/profile");
		if (input != NULL) {
			remember_FILE(input);
			install_special_sighandlers();
			parse_and_run_file(input);
			fclose_and_forget(input);
		}
		/* bash: after sourcing /etc/profile,
		 * tries to source (in the given order):
		 * ~/.bash_profile, ~/.bash_login, ~/.profile,
		 * stopping on first found. --noprofile turns this off.
		 * bash also sources ~/.bash_logout on exit.
		 * If called as sh, skips .bash_XXX files.
		 */
	}

	if (G.global_argv[1]) {
		FILE *input;
		/*
		 * "bash <script>" (which is never interactive (unless -i?))
		 * sources $BASH_ENV here (without scanning $PATH).
		 * If called as sh, does the same but with $ENV.
		 * Also NB, per POSIX, $ENV should undergo parameter expansion.
		 */
		G.global_argc--;
		G.global_argv++;
		debug_printf("running script '%s'\n", G.global_argv[0]);
		xfunc_error_retval = 127; /* for "hush /does/not/exist" case */
		input = xfopen_for_read(G.global_argv[0]);
		xfunc_error_retval = 1;
		remember_FILE(input);
		install_special_sighandlers();
		parse_and_run_file(input);
#if ENABLE_FEATURE_CLEAN_UP
		fclose_and_forget(input);
#endif
		goto final_return;
	}

	/* Up to here, shell was non-interactive. Now it may become one.
	 * NB: don't forget to (re)run install_special_sighandlers() as needed.
	 */

	/* A shell is interactive if the '-i' flag was given,
	 * or if all of the following conditions are met:
	 *    no -c command
	 *    no arguments remaining or the -s flag given
	 *    standard input is a terminal
	 *    standard output is a terminal
	 * Refer to Posix.2, the description of the 'sh' utility.
	 */
#if ENABLE_HUSH_JOB
	if (isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)) {
		G_saved_tty_pgrp = tcgetpgrp(STDIN_FILENO);
		debug_printf("saved_tty_pgrp:%d\n", G_saved_tty_pgrp);
		if (G_saved_tty_pgrp < 0)
			G_saved_tty_pgrp = 0;

		/* try to dup stdin to high fd#, >= 255 */
		G_interactive_fd = fcntl_F_DUPFD(STDIN_FILENO, 254);
		if (G_interactive_fd < 0) {
			/* try to dup to any fd */
			G_interactive_fd = dup(STDIN_FILENO);
			if (G_interactive_fd < 0) {
				/* give up */
				G_interactive_fd = 0;
				G_saved_tty_pgrp = 0;
			}
		}
// TODO: track & disallow any attempts of user
// to (inadvertently) close/redirect G_interactive_fd
	}
	debug_printf("interactive_fd:%d\n", G_interactive_fd);
	if (G_interactive_fd) {
		close_on_exec_on(G_interactive_fd);

		if (G_saved_tty_pgrp) {
			/* If we were run as 'hush &', sleep until we are
			 * in the foreground (tty pgrp == our pgrp).
			 * If we get started under a job aware app (like bash),
			 * make sure we are now in charge so we don't fight over
			 * who gets the foreground */
			while (1) {
				pid_t shell_pgrp = getpgrp();
				G_saved_tty_pgrp = tcgetpgrp(G_interactive_fd);
				if (G_saved_tty_pgrp == shell_pgrp)
					break;
				/* send TTIN to ourself (should stop us) */
				kill(- shell_pgrp, SIGTTIN);
			}
		}

		/* Install more signal handlers */
		install_special_sighandlers();

		if (G_saved_tty_pgrp) {
			/* Set other signals to restore saved_tty_pgrp */
			install_fatal_sighandlers();
			/* Put ourselves in our own process group
			 * (bash, too, does this only if ctty is available) */
			bb_setpgrp(); /* is the same as setpgid(our_pid, our_pid); */
			/* Grab control of the terminal */
			tcsetpgrp(G_interactive_fd, getpid());
		}
		enable_restore_tty_pgrp_on_exit();

# if ENABLE_HUSH_SAVEHISTORY && MAX_HISTORY > 0
		{
			const char *hp = get_local_var_value("HISTFILE");
			if (!hp) {
				hp = get_local_var_value("HOME");
				if (hp)
					hp = concat_path_file(hp, ".hush_history");
			} else {
				hp = xstrdup(hp);
			}
			if (hp) {
				G.line_input_state->hist_file = hp;
				//set_local_var(xasprintf("HISTFILE=%s", ...));
			}
#  if ENABLE_FEATURE_SH_HISTFILESIZE
			hp = get_local_var_value("HISTFILESIZE");
			G.line_input_state->max_history = size_from_HISTFILESIZE(hp);
#  endif
		}
# endif
	} else {
		install_special_sighandlers();
	}
#elif ENABLE_HUSH_INTERACTIVE
	/* No job control compiled in, only prompt/line editing */
	if (isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)) {
		G_interactive_fd = fcntl_F_DUPFD(STDIN_FILENO, 254);
		if (G_interactive_fd < 0) {
			/* try to dup to any fd */
			G_interactive_fd = dup(STDIN_FILENO);
			if (G_interactive_fd < 0)
				/* give up */
				G_interactive_fd = 0;
		}
	}
	if (G_interactive_fd) {
		close_on_exec_on(G_interactive_fd);
	}
	install_special_sighandlers();
#else
	/* We have interactiveness code disabled */
	install_special_sighandlers();
#endif
	/* bash:
	 * if interactive but not a login shell, sources ~/.bashrc
	 * (--norc turns this off, --rcfile <file> overrides)
	 */

	if (!ENABLE_FEATURE_SH_EXTRA_QUIET && G_interactive_fd) {
		/* note: ash and hush share this string */
		printf("\n\n%s %s\n"
			IF_HUSH_HELP("Enter 'help' for a list of built-in commands.\n")
			"\n",
			bb_banner,
			"hush - the humble shell"
		);
	}

	parse_and_run_file(stdin);

 final_return:
	hush_exit(G.last_exitcode);
}


/*
 * Built-ins
 */
static int FAST_FUNC builtin_true(char **argv UNUSED_PARAM)
{
	return 0;
}

#if ENABLE_HUSH_TEST || ENABLE_HUSH_ECHO || ENABLE_HUSH_PRINTF || ENABLE_HUSH_KILL
static int run_applet_main(char **argv, int (*applet_main_func)(int argc, char **argv))
{
	int argc = string_array_len(argv);
	return applet_main_func(argc, argv);
}
#endif
#if ENABLE_HUSH_TEST || BASH_TEST2
static int FAST_FUNC builtin_test(char **argv)
{
	return run_applet_main(argv, test_main);
}
#endif
#if ENABLE_HUSH_ECHO
static int FAST_FUNC builtin_echo(char **argv)
{
	return run_applet_main(argv, echo_main);
}
#endif
#if ENABLE_HUSH_PRINTF
static int FAST_FUNC builtin_printf(char **argv)
{
	return run_applet_main(argv, printf_main);
}
#endif

#if ENABLE_HUSH_HELP
static int FAST_FUNC builtin_help(char **argv UNUSED_PARAM)
{
	const struct built_in_command *x;

	printf(
		"Built-in commands:\n"
		"------------------\n");
	for (x = bltins1; x != &bltins1[ARRAY_SIZE(bltins1)]; x++) {
		if (x->b_descr)
			printf("%-10s%s\n", x->b_cmd, x->b_descr);
	}
	return EXIT_SUCCESS;
}
#endif

#if MAX_HISTORY && ENABLE_FEATURE_EDITING
static int FAST_FUNC builtin_history(char **argv UNUSED_PARAM)
{
	show_history(G.line_input_state);
	return EXIT_SUCCESS;
}
#endif

static char **skip_dash_dash(char **argv)
{
	argv++;
	if (argv[0] && argv[0][0] == '-' && argv[0][1] == '-' && argv[0][2] == '\0')
		argv++;
	return argv;
}

static int FAST_FUNC builtin_cd(char **argv)
{
	const char *newdir;

	argv = skip_dash_dash(argv);
	newdir = argv[0];
	if (newdir == NULL) {
		/* bash does nothing (exitcode 0) if HOME is ""; if it's unset,
		 * bash says "bash: cd: HOME not set" and does nothing
		 * (exitcode 1)
		 */
		const char *home = get_local_var_value("HOME");
		newdir = home ? home : "/";
	}
	if (chdir(newdir)) {
		/* Mimic bash message exactly */
		bb_perror_msg("cd: %s", newdir);
		return EXIT_FAILURE;
	}
	/* Read current dir (get_cwd(1) is inside) and set PWD.
	 * Note: do not enforce exporting. If PWD was unset or unexported,
	 * set it again, but do not export. bash does the same.
	 */
	set_pwd_var(/*flag:*/ 0);
	return EXIT_SUCCESS;
}

static int FAST_FUNC builtin_pwd(char **argv UNUSED_PARAM)
{
	puts(get_cwd(0));
	return EXIT_SUCCESS;
}

static int FAST_FUNC builtin_eval(char **argv)
{
	int rcode = EXIT_SUCCESS;

	argv = skip_dash_dash(argv);
	if (*argv) {
		char *str = expand_strvec_to_string(argv);
		/* bash:
		 * eval "echo Hi; done" ("done" is syntax error):
		 * "echo Hi" will not execute too.
		 */
		parse_and_run_string(str);
		free(str);
		rcode = G.last_exitcode;
	}
	return rcode;
}

static int FAST_FUNC builtin_exec(char **argv)
{
	argv = skip_dash_dash(argv);
	if (argv[0] == NULL)
		return EXIT_SUCCESS; /* bash does this */

	/* Careful: we can end up here after [v]fork. Do not restore
	 * tty pgrp then, only top-level shell process does that */
	if (G_saved_tty_pgrp && getpid() == G.root_pid)
		tcsetpgrp(G_interactive_fd, G_saved_tty_pgrp);

	/* Saved-redirect fds, script fds and G_interactive_fd are still
	 * open here. However, they are all CLOEXEC, and execv below
	 * closes them. Try interactive "exec ls -l /proc/self/fd",
	 * it should show no extra open fds in the "ls" process.
	 * If we'd try to run builtins/NOEXECs, this would need improving.
	 */
	//close_saved_fds_and_FILE_fds();

	/* TODO: if exec fails, bash does NOT exit! We do.
	 * We'll need to undo trap cleanup (it's inside execvp_or_die)
	 * and tcsetpgrp, and this is inherently racy.
	 */
	execvp_or_die(argv);
}

static int FAST_FUNC builtin_exit(char **argv)
{
	debug_printf_exec("%s()\n", __func__);

	/* interactive bash:
	 * # trap "echo EEE" EXIT
	 * # exit
	 * exit
	 * There are stopped jobs.
	 * (if there are _stopped_ jobs, running ones don't count)
	 * # exit
	 * exit
	 * EEE (then bash exits)
	 *
	 * TODO: we can use G.exiting = -1 as indicator "last cmd was exit"
	 */

	/* note: EXIT trap is run by hush_exit */
	argv = skip_dash_dash(argv);
	if (argv[0] == NULL)
		hush_exit(G.last_exitcode);
	/* mimic bash: exit 123abc == exit 255 + error msg */
	xfunc_error_retval = 255;
	/* bash: exit -2 == exit 254, no error msg */
	hush_exit(xatoi(argv[0]) & 0xff);
}

#if ENABLE_HUSH_TYPE
/* http://www.opengroup.org/onlinepubs/9699919799/utilities/type.html */
static int FAST_FUNC builtin_type(char **argv)
{
	int ret = EXIT_SUCCESS;

	while (*++argv) {
		const char *type;
		char *path = NULL;

		if (0) {} /* make conditional compile easier below */
		/*else if (find_alias(*argv))
			type = "an alias";*/
#if ENABLE_HUSH_FUNCTIONS
		else if (find_function(*argv))
			type = "a function";
#endif
		else if (find_builtin(*argv))
			type = "a shell builtin";
		else if ((path = find_in_path(*argv)) != NULL)
			type = path;
		else {
			bb_error_msg("type: %s: not found", *argv);
			ret = EXIT_FAILURE;
			continue;
		}

		printf("%s is %s\n", *argv, type);
		free(path);
	}

	return ret;
}
#endif

#if ENABLE_HUSH_READ
/* Interruptibility of read builtin in bash
 * (tested on bash-4.2.8 by sending signals (not by ^C)):
 *
 * Empty trap makes read ignore corresponding signal, for any signal.
 *
 * SIGINT:
 * - terminates non-interactive shell;
 * - interrupts read in interactive shell;
 * if it has non-empty trap:
 * - executes trap and returns to command prompt in interactive shell;
 * - executes trap and returns to read in non-interactive shell;
 * SIGTERM:
 * - is ignored (does not interrupt) read in interactive shell;
 * - terminates non-interactive shell;
 * if it has non-empty trap:
 * - executes trap and returns to read;
 * SIGHUP:
 * - terminates shell (regardless of interactivity);
 * if it has non-empty trap:
 * - executes trap and returns to read;
 * SIGCHLD from children:
 * - does not interrupt read regardless of interactivity:
 *   try: sleep 1 & read x; echo $x
 */
static int FAST_FUNC builtin_read(char **argv)
{
	const char *r;
	char *opt_n = NULL;
	char *opt_p = NULL;
	char *opt_t = NULL;
	char *opt_u = NULL;
	char *opt_d = NULL; /* optimized out if !BASH */
	const char *ifs;
	int read_flags;

	/* "!": do not abort on errors.
	 * Option string must start with "sr" to match BUILTIN_READ_xxx
	 */
	read_flags = getopt32(argv,
#if BASH_READ_D
		"!srn:p:t:u:d:", &opt_n, &opt_p, &opt_t, &opt_u, &opt_d
#else
		"!srn:p:t:u:", &opt_n, &opt_p, &opt_t, &opt_u
#endif
	);
	if (read_flags == (uint32_t)-1)
		return EXIT_FAILURE;
	argv += optind;
	ifs = get_local_var_value("IFS"); /* can be NULL */

 again:
	r = shell_builtin_read(set_local_var_from_halves,
		argv,
		ifs,
		read_flags,
		opt_n,
		opt_p,
		opt_t,
		opt_u,
		opt_d
	);

	if ((uintptr_t)r == 1 && errno == EINTR) {
		unsigned sig = check_and_run_traps();
		if (sig != SIGINT)
			goto again;
	}

	if ((uintptr_t)r > 1) {
		bb_error_msg("%s", r);
		r = (char*)(uintptr_t)1;
	}

	return (uintptr_t)r;
}
#endif

#if ENABLE_HUSH_UMASK
static int FAST_FUNC builtin_umask(char **argv)
{
	int rc;
	mode_t mask;

	rc = 1;
	mask = umask(0);
	argv = skip_dash_dash(argv);
	if (argv[0]) {
		mode_t old_mask = mask;

		/* numeric umasks are taken as-is */
		/* symbolic umasks are inverted: "umask a=rx" calls umask(222) */
		if (!isdigit(argv[0][0]))
			mask ^= 0777;
		mask = bb_parse_mode(argv[0], mask);
		if (!isdigit(argv[0][0]))
			mask ^= 0777;
		if ((unsigned)mask > 0777) {
			mask = old_mask;
			/* bash messages:
			 * bash: umask: 'q': invalid symbolic mode operator
			 * bash: umask: 999: octal number out of range
			 */
			bb_error_msg("%s: invalid mode '%s'", "umask", argv[0]);
			rc = 0;
		}
	} else {
		/* Mimic bash */
		printf("%04o\n", (unsigned) mask);
		/* fall through and restore mask which we set to 0 */
	}
	umask(mask);

	return !rc; /* rc != 0 - success */
}
#endif

#if ENABLE_HUSH_EXPORT || ENABLE_HUSH_TRAP
static void print_escaped(const char *s)
{
	if (*s == '\'')
		goto squote;
	do {
		const char *p = strchrnul(s, '\'');
		/* print 'xxxx', possibly just '' */
		printf("'%.*s'", (int)(p - s), s);
		if (*p == '\0')
			break;
		s = p;
 squote:
		/* s points to '; print "'''...'''" */
		putchar('"');
		do putchar('\''); while (*++s == '\'');
		putchar('"');
	} while (*s);
}
#endif

#if ENABLE_HUSH_EXPORT || ENABLE_HUSH_LOCAL || ENABLE_HUSH_READONLY
static int helper_export_local(char **argv, unsigned flags)
{
	do {
		char *name = *argv;
		char *name_end = strchrnul(name, '=');

		/* So far we do not check that name is valid (TODO?) */

		if (*name_end == '\0') {
			struct variable *var, **vpp;

			vpp = get_ptr_to_local_var(name, name_end - name);
			var = vpp ? *vpp : NULL;

			if (flags & SETFLAG_UNEXPORT) {
				/* export -n NAME (without =VALUE) */
				if (var) {
					var->flg_export = 0;
					debug_printf_env("%s: unsetenv '%s'\n", __func__, name);
					unsetenv(name);
				} /* else: export -n NOT_EXISTING_VAR: no-op */
				continue;
			}
			if (flags & SETFLAG_EXPORT) {
				/* export NAME (without =VALUE) */
				if (var) {
					var->flg_export = 1;
					debug_printf_env("%s: putenv '%s'\n", __func__, var->varstr);
					putenv(var->varstr);
					continue;
				}
			}
			if (flags & SETFLAG_MAKE_RO) {
				/* readonly NAME (without =VALUE) */
				if (var) {
					var->flg_read_only = 1;
					continue;
				}
			}
# if ENABLE_HUSH_LOCAL
			/* Is this "local" bltin? */
			if (!(flags & (SETFLAG_EXPORT|SETFLAG_UNEXPORT|SETFLAG_MAKE_RO))) {
				unsigned lvl = flags >> SETFLAG_LOCAL_SHIFT;
				if (var && var->func_nest_level == lvl) {
					/* "local x=abc; ...; local x" - ignore second local decl */
					continue;
				}
			}
# endif
			/* Exporting non-existing variable.
			 * bash does not put it in environment,
			 * but remembers that it is exported,
			 * and does put it in env when it is set later.
			 * We just set it to "" and export.
			 */
			/* Or, it's "local NAME" (without =VALUE).
			 * bash sets the value to "".
			 */
			/* Or, it's "readonly NAME" (without =VALUE).
			 * bash remembers NAME and disallows its creation
			 * in the future.
			 */
			name = xasprintf("%s=", name);
		} else {
			/* (Un)exporting/making local NAME=VALUE */
			name = xstrdup(name);
		}
		if (set_local_var(name, flags))
			return EXIT_FAILURE;
	} while (*++argv);
	return EXIT_SUCCESS;
}
#endif

#if ENABLE_HUSH_EXPORT
static int FAST_FUNC builtin_export(char **argv)
{
	unsigned opt_unexport;

#if ENABLE_HUSH_EXPORT_N
	/* "!": do not abort on errors */
	opt_unexport = getopt32(argv, "!n");
	if (opt_unexport == (uint32_t)-1)
		return EXIT_FAILURE;
	argv += optind;
#else
	opt_unexport = 0;
	argv++;
#endif

	if (argv[0] == NULL) {
		char **e = environ;
		if (e) {
			while (*e) {
#if 0
				puts(*e++);
#else
				/* ash emits: export VAR='VAL'
				 * bash: declare -x VAR="VAL"
				 * we follow ash example */
				const char *s = *e++;
				const char *p = strchr(s, '=');

				if (!p) /* wtf? take next variable */
					continue;
				/* export var= */
				printf("export %.*s", (int)(p - s) + 1, s);
				print_escaped(p + 1);
				putchar('\n');
#endif
			}
			/*fflush_all(); - done after each builtin anyway */
		}
		return EXIT_SUCCESS;
	}

	return helper_export_local(argv, opt_unexport ? SETFLAG_UNEXPORT : SETFLAG_EXPORT);
}
#endif

#if ENABLE_HUSH_LOCAL
static int FAST_FUNC builtin_local(char **argv)
{
	if (G.func_nest_level == 0) {
		bb_error_msg("%s: not in a function", argv[0]);
		return EXIT_FAILURE; /* bash compat */
	}
	argv++;
	return helper_export_local(argv, G.func_nest_level << SETFLAG_LOCAL_SHIFT);
}
#endif

#if ENABLE_HUSH_READONLY
static int FAST_FUNC builtin_readonly(char **argv)
{
	argv++;
	if (*argv == NULL) {
		/* bash: readonly [-p]: list all readonly VARs
		 * (-p has no effect in bash)
		 */
		struct variable *e;
		for (e = G.top_var; e; e = e->next) {
			if (e->flg_read_only) {
//TODO: quote value: readonly VAR='VAL'
				printf("readonly %s\n", e->varstr);
			}
		}
		return EXIT_SUCCESS;
	}
	return helper_export_local(argv, SETFLAG_MAKE_RO);
}
#endif

#if ENABLE_HUSH_UNSET
/* http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#unset */
static int FAST_FUNC builtin_unset(char **argv)
{
	int ret;
	unsigned opts;

	/* "!": do not abort on errors */
	/* "+": stop at 1st non-option */
	opts = getopt32(argv, "!+vf");
	if (opts == (unsigned)-1)
		return EXIT_FAILURE;
	if (opts == 3) {
		bb_error_msg("unset: -v and -f are exclusive");
		return EXIT_FAILURE;
	}
	argv += optind;

	ret = EXIT_SUCCESS;
	while (*argv) {
		if (!(opts & 2)) { /* not -f */
			if (unset_local_var(*argv)) {
				/* unset <nonexistent_var> doesn't fail.
				 * Error is when one tries to unset RO var.
				 * Message was printed by unset_local_var. */
				ret = EXIT_FAILURE;
			}
		}
# if ENABLE_HUSH_FUNCTIONS
		else {
			unset_func(*argv);
		}
# endif
		argv++;
	}
	return ret;
}
#endif

#if ENABLE_HUSH_SET
/* http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#set
 * built-in 'set' handler
 * SUSv3 says:
 * set [-abCefhmnuvx] [-o option] [argument...]
 * set [+abCefhmnuvx] [+o option] [argument...]
 * set -- [argument...]
 * set -o
 * set +o
 * Implementations shall support the options in both their hyphen and
 * plus-sign forms. These options can also be specified as options to sh.
 * Examples:
 * Write out all variables and their values: set
 * Set $1, $2, and $3 and set "$#" to 3: set c a b
 * Turn on the -x and -v options: set -xv
 * Unset all positional parameters: set --
 * Set $1 to the value of x, even if it begins with '-' or '+': set -- "$x"
 * Set the positional parameters to the expansion of x, even if x expands
 * with a leading '-' or '+': set -- $x
 *
 * So far, we only support "set -- [argument...]" and some of the short names.
 */
static int FAST_FUNC builtin_set(char **argv)
{
	int n;
	char **pp, **g_argv;
	char *arg = *++argv;

	if (arg == NULL) {
		struct variable *e;
		for (e = G.top_var; e; e = e->next)
			puts(e->varstr);
		return EXIT_SUCCESS;
	}

	do {
		if (strcmp(arg, "--") == 0) {
			++argv;
			goto set_argv;
		}
		if (arg[0] != '+' && arg[0] != '-')
			break;
		for (n = 1; arg[n]; ++n) {
			if (set_mode((arg[0] == '-'), arg[n], argv[1]))
				goto error;
			if (arg[n] == 'o' && argv[1])
				argv++;
		}
	} while ((arg = *++argv) != NULL);
	/* Now argv[0] is 1st argument */

	if (arg == NULL)
		return EXIT_SUCCESS;
 set_argv:

	/* NB: G.global_argv[0] ($0) is never freed/changed */
	g_argv = G.global_argv;
	if (G.global_args_malloced) {
		pp = g_argv;
		while (*++pp)
			free(*pp);
		g_argv[1] = NULL;
	} else {
		G.global_args_malloced = 1;
		pp = xzalloc(sizeof(pp[0]) * 2);
		pp[0] = g_argv[0]; /* retain $0 */
		g_argv = pp;
	}
	/* This realloc's G.global_argv */
	G.global_argv = pp = add_strings_to_strings(g_argv, argv, /*dup:*/ 1);

	G.global_argc = 1 + string_array_len(pp + 1);

	return EXIT_SUCCESS;

	/* Nothing known, so abort */
 error:
	bb_error_msg("set: %s: invalid option", arg);
	return EXIT_FAILURE;
}
#endif

static int FAST_FUNC builtin_shift(char **argv)
{
	int n = 1;
	argv = skip_dash_dash(argv);
	if (argv[0]) {
		n = bb_strtou(argv[0], NULL, 10);
		if (errno || n < 0) {
			/* shared string with ash.c */
			bb_error_msg("Illegal number: %s", argv[0]);
			/*
			 * ash aborts in this case.
			 * bash prints error message and set $? to 1.
			 * Interestingly, for "shift 99999" bash does not
			 * print error message, but does set $? to 1
			 * (and does no shifting at all).
			 */
		}
	}
	if (n >= 0 && n < G.global_argc) {
		if (G_global_args_malloced) {
			int m = 1;
			while (m <= n)
				free(G.global_argv[m++]);
		}
		G.global_argc -= n;
		memmove(&G.global_argv[1], &G.global_argv[n+1],
				G.global_argc * sizeof(G.global_argv[0]));
		return EXIT_SUCCESS;
	}
	return EXIT_FAILURE;
}

#if ENABLE_HUSH_GETOPTS
static int FAST_FUNC builtin_getopts(char **argv)
{
/*
TODO:
If an invalid option is seen, getopts places ? into VAR and, if
not silent, prints an error message and unsets OPTARG. If
getopts is silent, the option character found is placed in
OPTARG and no diagnostic message is printed.

If a required argument is not found, and getopts is not silent,
a question mark (?) is placed in VAR, OPTARG is unset, and a
diagnostic message is printed.  If getopts is silent, then a
colon (:) is placed in VAR and OPTARG is set to the option
character found.

Test that VAR is a valid variable name?
*/
	char cbuf[2];
	const char *cp, *optstring, *var;
	int c, exitcode;

	optstring = *++argv;
	if (!optstring || !(var = *++argv)) {
		bb_error_msg("usage: getopts OPTSTRING VAR [ARGS]");
		return EXIT_FAILURE;
	}

	cp = get_local_var_value("OPTERR");
	opterr = cp ? atoi(cp) : 1;
	cp = get_local_var_value("OPTIND");
	optind = cp ? atoi(cp) : 0;
	optarg = NULL;

	/* getopts stops on first non-option. Add "+" to force that */
	/*if (optstring[0] != '+')*/ {
		char *s = alloca(strlen(optstring) + 2);
		sprintf(s, "+%s", optstring);
		optstring = s;
	}

	if (argv[1])
		argv[0] = G.global_argv[0]; /* for error messages */
	else
		argv = G.global_argv;
	c = getopt(string_array_len(argv), argv, optstring);
	exitcode = EXIT_SUCCESS;
	if (c < 0) { /* -1: end of options */
		exitcode = EXIT_FAILURE;
		c = '?';
	}
	if (optarg)
		set_local_var_from_halves("OPTARG", optarg);
	else
		unset_local_var("OPTARG");
	cbuf[0] = c;
	cbuf[1] = '\0';
	set_local_var_from_halves(var, cbuf);
	set_local_var_from_halves("OPTIND", utoa(optind));
	return exitcode;
}
#endif

static int FAST_FUNC builtin_source(char **argv)
{
	char *arg_path, *filename;
	FILE *input;
	save_arg_t sv;
	char *args_need_save;
#if ENABLE_HUSH_FUNCTIONS
	smallint sv_flg;
#endif

	argv = skip_dash_dash(argv);
	filename = argv[0];
	if (!filename) {
		/* bash says: "bash: .: filename argument required" */
		return 2; /* bash compat */
	}
	arg_path = NULL;
	if (!strchr(filename, '/')) {
		arg_path = find_in_path(filename);
		if (arg_path)
			filename = arg_path;
	}
	input = remember_FILE(fopen_or_warn(filename, "r"));
	free(arg_path);
	if (!input) {
		/* bb_perror_msg("%s", *argv); - done by fopen_or_warn */
		/* POSIX: non-interactive shell should abort here,
		 * not merely fail. So far no one complained :)
		 */
		return EXIT_FAILURE;
	}

#if ENABLE_HUSH_FUNCTIONS
	sv_flg = G_flag_return_in_progress;
	/* "we are inside sourced file, ok to use return" */
	G_flag_return_in_progress = -1;
#endif
	args_need_save = argv[1]; /* used as a boolean variable */
	if (args_need_save)
		save_and_replace_G_args(&sv, argv);

	/* "false; . ./empty_line; echo Zero:$?" should print 0 */
	G.last_exitcode = 0;
	parse_and_run_file(input);
	fclose_and_forget(input);

	if (args_need_save) /* can't use argv[1] instead: "shift" can mangle it */
		restore_G_args(&sv, argv);
#if ENABLE_HUSH_FUNCTIONS
	G_flag_return_in_progress = sv_flg;
#endif

	return G.last_exitcode;
}

#if ENABLE_HUSH_TRAP
static int FAST_FUNC builtin_trap(char **argv)
{
	int sig;
	char *new_cmd;

	if (!G_traps)
		G_traps = xzalloc(sizeof(G_traps[0]) * NSIG);

	argv++;
	if (!*argv) {
		int i;
		/* No args: print all trapped */
		for (i = 0; i < NSIG; ++i) {
			if (G_traps[i]) {
				printf("trap -- ");
				print_escaped(G_traps[i]);
				/* note: bash adds "SIG", but only if invoked
				 * as "bash". If called as "sh", or if set -o posix,
				 * then it prints short signal names.
				 * We are printing short names: */
				printf(" %s\n", get_signame(i));
			}
		}
		/*fflush_all(); - done after each builtin anyway */
		return EXIT_SUCCESS;
	}

	new_cmd = NULL;
	/* If first arg is a number: reset all specified signals */
	sig = bb_strtou(*argv, NULL, 10);
	if (errno == 0) {
		int ret;
 process_sig_list:
		ret = EXIT_SUCCESS;
		while (*argv) {
			sighandler_t handler;

			sig = get_signum(*argv++);
			if (sig < 0) {
				ret = EXIT_FAILURE;
				/* Mimic bash message exactly */
				bb_error_msg("trap: %s: invalid signal specification", argv[-1]);
				continue;
			}

			free(G_traps[sig]);
			G_traps[sig] = xstrdup(new_cmd);

			debug_printf("trap: setting SIG%s (%i) to '%s'\n",
				get_signame(sig), sig, G_traps[sig]);

			/* There is no signal for 0 (EXIT) */
			if (sig == 0)
				continue;

			if (new_cmd)
				handler = (new_cmd[0] ? record_pending_signo : SIG_IGN);
			else
				/* We are removing trap handler */
				handler = pick_sighandler(sig);
			install_sighandler(sig, handler);
		}
		return ret;
	}

	if (!argv[1]) { /* no second arg */
		bb_error_msg("trap: invalid arguments");
		return EXIT_FAILURE;
	}

	/* First arg is "-": reset all specified to default */
	/* First arg is "--": skip it, the rest is "handler SIGs..." */
	/* Everything else: set arg as signal handler
	 * (includes "" case, which ignores signal) */
	if (argv[0][0] == '-') {
		if (argv[0][1] == '\0') { /* "-" */
			/* new_cmd remains NULL: "reset these sigs" */
			goto reset_traps;
		}
		if (argv[0][1] == '-' && argv[0][2] == '\0') { /* "--" */
			argv++;
		}
		/* else: "-something", no special meaning */
	}
	new_cmd = *argv;
 reset_traps:
	argv++;
	goto process_sig_list;
}
#endif

#if ENABLE_HUSH_JOB
static struct pipe *parse_jobspec(const char *str)
{
	struct pipe *pi;
	unsigned jobnum;

	if (sscanf(str, "%%%u", &jobnum) != 1) {
		if (str[0] != '%'
		 || (str[1] != '%' && str[1] != '+' && str[1] != '\0')
		) {
			bb_error_msg("bad argument '%s'", str);
			return NULL;
		}
		/* It is "%%", "%+" or "%" - current job */
		jobnum = G.last_jobid;
		if (jobnum == 0) {
			bb_error_msg("no current job");
			return NULL;
		}
	}
	for (pi = G.job_list; pi; pi = pi->next) {
		if (pi->jobid == jobnum) {
			return pi;
		}
	}
	bb_error_msg("%u: no such job", jobnum);
	return NULL;
}

static int FAST_FUNC builtin_jobs(char **argv UNUSED_PARAM)
{
	struct pipe *job;
	const char *status_string;

	checkjobs(NULL, 0 /*(no pid to wait for)*/);
	for (job = G.job_list; job; job = job->next) {
		if (job->alive_cmds == job->stopped_cmds)
			status_string = "Stopped";
		else
			status_string = "Running";

		printf(JOB_STATUS_FORMAT, job->jobid, status_string, job->cmdtext);
	}

	clean_up_last_dead_job();

	return EXIT_SUCCESS;
}

/* built-in 'fg' and 'bg' handler */
static int FAST_FUNC builtin_fg_bg(char **argv)
{
	int i;
	struct pipe *pi;

	if (!G_interactive_fd)
		return EXIT_FAILURE;

	/* If they gave us no args, assume they want the last backgrounded task */
	if (!argv[1]) {
		for (pi = G.job_list; pi; pi = pi->next) {
			if (pi->jobid == G.last_jobid) {
				goto found;
			}
		}
		bb_error_msg("%s: no current job", argv[0]);
		return EXIT_FAILURE;
	}

	pi = parse_jobspec(argv[1]);
	if (!pi)
		return EXIT_FAILURE;
 found:
	/* TODO: bash prints a string representation
	 * of job being foregrounded (like "sleep 1 | cat") */
	if (argv[0][0] == 'f' && G_saved_tty_pgrp) {
		/* Put the job into the foreground.  */
		tcsetpgrp(G_interactive_fd, pi->pgrp);
	}

	/* Restart the processes in the job */
	debug_printf_jobs("reviving %d procs, pgrp %d\n", pi->num_cmds, pi->pgrp);
	for (i = 0; i < pi->num_cmds; i++) {
		debug_printf_jobs("reviving pid %d\n", pi->cmds[i].pid);
	}
	pi->stopped_cmds = 0;

	i = kill(- pi->pgrp, SIGCONT);
	if (i < 0) {
		if (errno == ESRCH) {
			delete_finished_job(pi);
			return EXIT_SUCCESS;
		}
		bb_perror_msg("kill (SIGCONT)");
	}

	if (argv[0][0] == 'f') {
		remove_job_from_table(pi); /* FG job shouldn't be in job table */
		return checkjobs_and_fg_shell(pi);
	}
	return EXIT_SUCCESS;
}
#endif

#if ENABLE_HUSH_KILL
static int FAST_FUNC builtin_kill(char **argv)
{
	int ret = 0;

# if ENABLE_HUSH_JOB
	if (argv[1] && strcmp(argv[1], "-l") != 0) {
		int i = 1;

		do {
			struct pipe *pi;
			char *dst;
			int j, n;

			if (argv[i][0] != '%')
				continue;
			/*
			 * "kill %N" - job kill
			 * Converting to pgrp / pid kill
			 */
			pi = parse_jobspec(argv[i]);
			if (!pi) {
				/* Eat bad jobspec */
				j = i;
				do {
					j++;
					argv[j - 1] = argv[j];
				} while (argv[j]);
				ret = 1;
				i--;
				continue;
			}
			/*
			 * In jobs started under job control, we signal
			 * entire process group by kill -PGRP_ID.
			 * This happens, f.e., in interactive shell.
			 *
			 * Otherwise, we signal each child via
			 * kill PID1 PID2 PID3.
			 * Testcases:
			 * sh -c 'sleep 1|sleep 1 & kill %1'
			 * sh -c 'true|sleep 2 & sleep 1; kill %1'
			 * sh -c 'true|sleep 1 & sleep 2; kill %1'
			 */
			n = G_interactive_fd ? 1 : pi->num_cmds;
			dst = alloca(n * sizeof(int)*4);
			argv[i] = dst;
			if (G_interactive_fd)
				dst += sprintf(dst, " -%u", (int)pi->pgrp);
			else for (j = 0; j < n; j++) {
				struct command *cmd = &pi->cmds[j];
				/* Skip exited members of the job */
				if (cmd->pid == 0)
					continue;
				/*
				 * kill_main has matching code to expect
				 * leading space. Needed to not confuse
				 * negative pids with "kill -SIGNAL_NO" syntax
				 */
				dst += sprintf(dst, " %u", (int)cmd->pid);
			}
			*dst = '\0';
		} while (argv[++i]);
	}
# endif

	if (argv[1] || ret == 0) {
		ret = run_applet_main(argv, kill_main);
	}
	/* else: ret = 1, "kill %bad_jobspec" case */
	return ret;
}
#endif

#if ENABLE_HUSH_WAIT
/* http://www.opengroup.org/onlinepubs/9699919799/utilities/wait.html */
#if !ENABLE_HUSH_JOB
# define wait_for_child_or_signal(pipe,pid) wait_for_child_or_signal(pid)
#endif
static int wait_for_child_or_signal(struct pipe *waitfor_pipe, pid_t waitfor_pid)
{
	int ret = 0;
	for (;;) {
		int sig;
		sigset_t oldset;

		if (!sigisemptyset(&G.pending_set))
			goto check_sig;

		/* waitpid is not interruptible by SA_RESTARTed
		 * signals which we use. Thus, this ugly dance:
		 */

		/* Make sure possible SIGCHLD is stored in kernel's
		 * pending signal mask before we call waitpid.
		 * Or else we may race with SIGCHLD, lose it,
		 * and get stuck in sigsuspend...
		 */
		sigfillset(&oldset); /* block all signals, remember old set */
		sigprocmask(SIG_SETMASK, &oldset, &oldset);

		if (!sigisemptyset(&G.pending_set)) {
			/* Crap! we raced with some signal! */
			goto restore;
		}

		/*errno = 0; - checkjobs does this */
/* Can't pass waitfor_pipe into checkjobs(): it won't be interruptible */
		ret = checkjobs(NULL, waitfor_pid); /* waitpid(WNOHANG) inside */
		debug_printf_exec("checkjobs:%d\n", ret);
#if ENABLE_HUSH_JOB
		if (waitfor_pipe) {
			int rcode = job_exited_or_stopped(waitfor_pipe);
			debug_printf_exec("job_exited_or_stopped:%d\n", rcode);
			if (rcode >= 0) {
				ret = rcode;
				sigprocmask(SIG_SETMASK, &oldset, NULL);
				break;
			}
		}
#endif
		/* if ECHILD, there are no children (ret is -1 or 0) */
		/* if ret == 0, no children changed state */
		/* if ret != 0, it's exitcode+1 of exited waitfor_pid child */
		if (errno == ECHILD || ret) {
			ret--;
			if (ret < 0) /* if ECHILD, may need to fix "ret" */
				ret = 0;
			sigprocmask(SIG_SETMASK, &oldset, NULL);
			break;
		}
		/* Wait for SIGCHLD or any other signal */
		/* It is vitally important for sigsuspend that SIGCHLD has non-DFL handler! */
		/* Note: sigsuspend invokes signal handler */
		sigsuspend(&oldset);
 restore:
		sigprocmask(SIG_SETMASK, &oldset, NULL);
 check_sig:
		/* So, did we get a signal? */
		sig = check_and_run_traps();
		if (sig /*&& sig != SIGCHLD - always true */) {
			/* Do this for any (non-ignored) signal, not only for ^C */
			ret = 128 + sig;
			break;
		}
		/* SIGCHLD, or no signal, or ignored one, such as SIGQUIT. Repeat */
	}
	return ret;
}

static int FAST_FUNC builtin_wait(char **argv)
{
	int ret;
	int status;

	argv = skip_dash_dash(argv);
	if (argv[0] == NULL) {
		/* Don't care about wait results */
		/* Note 1: must wait until there are no more children */
		/* Note 2: must be interruptible */
		/* Examples:
		 * $ sleep 3 & sleep 6 & wait
		 * [1] 30934 sleep 3
		 * [2] 30935 sleep 6
		 * [1] Done                   sleep 3
		 * [2] Done                   sleep 6
		 * $ sleep 3 & sleep 6 & wait
		 * [1] 30936 sleep 3
		 * [2] 30937 sleep 6
		 * [1] Done                   sleep 3
		 * ^C <-- after ~4 sec from keyboard
		 * $
		 */
		return wait_for_child_or_signal(NULL, 0 /*(no job and no pid to wait for)*/);
	}

	do {
		pid_t pid = bb_strtou(*argv, NULL, 10);
		if (errno || pid <= 0) {
#if ENABLE_HUSH_JOB
			if (argv[0][0] == '%') {
				struct pipe *wait_pipe;
				ret = 127; /* bash compat for bad jobspecs */
				wait_pipe = parse_jobspec(*argv);
				if (wait_pipe) {
					ret = job_exited_or_stopped(wait_pipe);
					if (ret < 0) {
						ret = wait_for_child_or_signal(wait_pipe, 0);
					} else {
						/* waiting on "last dead job" removes it */
						clean_up_last_dead_job();
					}
				}
				/* else: parse_jobspec() already emitted error msg */
				continue;
			}
#endif
			/* mimic bash message */
			bb_error_msg("wait: '%s': not a pid or valid job spec", *argv);
			ret = EXIT_FAILURE;
			continue; /* bash checks all argv[] */
		}

		/* Do we have such child? */
		ret = waitpid(pid, &status, WNOHANG);
		if (ret < 0) {
			/* No */
			ret = 127;
			if (errno == ECHILD) {
				if (pid == G.last_bg_pid) {
					/* "wait $!" but last bg task has already exited. Try:
					 * (sleep 1; exit 3) & sleep 2; echo $?; wait $!; echo $?
					 * In bash it prints exitcode 0, then 3.
					 * In dash, it is 127.
					 */
					ret = G.last_bg_pid_exitcode;
				} else {
					/* Example: "wait 1". mimic bash message */
					bb_error_msg("wait: pid %d is not a child of this shell", (int)pid);
				}
			} else {
				/* ??? */
				bb_perror_msg("wait %s", *argv);
			}
			continue; /* bash checks all argv[] */
		}
		if (ret == 0) {
			/* Yes, and it still runs */
			ret = wait_for_child_or_signal(NULL, pid);
		} else {
			/* Yes, and it just exited */
			process_wait_result(NULL, pid, status);
			ret = WEXITSTATUS(status);
			if (WIFSIGNALED(status))
				ret = 128 + WTERMSIG(status);
		}
	} while (*++argv);

	return ret;
}
#endif

#if ENABLE_HUSH_LOOPS || ENABLE_HUSH_FUNCTIONS
static unsigned parse_numeric_argv1(char **argv, unsigned def, unsigned def_min)
{
	if (argv[1]) {
		def = bb_strtou(argv[1], NULL, 10);
		if (errno || def < def_min || argv[2]) {
			bb_error_msg("%s: bad arguments", argv[0]);
			def = UINT_MAX;
		}
	}
	return def;
}
#endif

#if ENABLE_HUSH_LOOPS
static int FAST_FUNC builtin_break(char **argv)
{
	unsigned depth;
	if (G.depth_of_loop == 0) {
		bb_error_msg("%s: only meaningful in a loop", argv[0]);
		/* if we came from builtin_continue(), need to undo "= 1" */
		G.flag_break_continue = 0;
		return EXIT_SUCCESS; /* bash compat */
	}
	G.flag_break_continue++; /* BC_BREAK = 1, or BC_CONTINUE = 2 */

	G.depth_break_continue = depth = parse_numeric_argv1(argv, 1, 1);
	if (depth == UINT_MAX)
		G.flag_break_continue = BC_BREAK;
	if (G.depth_of_loop < depth)
		G.depth_break_continue = G.depth_of_loop;

	return EXIT_SUCCESS;
}

static int FAST_FUNC builtin_continue(char **argv)
{
	G.flag_break_continue = 1; /* BC_CONTINUE = 2 = 1+1 */
	return builtin_break(argv);
}
#endif

#if ENABLE_HUSH_FUNCTIONS
static int FAST_FUNC builtin_return(char **argv)
{
	int rc;

	if (G_flag_return_in_progress != -1) {
		bb_error_msg("%s: not in a function or sourced script", argv[0]);
		return EXIT_FAILURE; /* bash compat */
	}

	G_flag_return_in_progress = 1;

	/* bash:
	 * out of range: wraps around at 256, does not error out
	 * non-numeric param:
	 * f() { false; return qwe; }; f; echo $?
	 * bash: return: qwe: numeric argument required  <== we do this
	 * 255  <== we also do this
	 */
	rc = parse_numeric_argv1(argv, G.last_exitcode, 0);
	return rc;
}
#endif

#if ENABLE_HUSH_TIMES
static int FAST_FUNC builtin_times(char **argv UNUSED_PARAM)
{
	static const uint8_t times_tbl[] ALIGN1 = {
		' ',  offsetof(struct tms, tms_utime),
		'\n', offsetof(struct tms, tms_stime),
		' ',  offsetof(struct tms, tms_cutime),
		'\n', offsetof(struct tms, tms_cstime),
		0
	};
	const uint8_t *p;
	unsigned clk_tck;
	struct tms buf;

	clk_tck = bb_clk_tck();

	times(&buf);
	p = times_tbl;
	do {
		unsigned sec, frac;
		unsigned long t;
		t = *(clock_t *)(((char *) &buf) + p[1]);
		sec = t / clk_tck;
		frac = t % clk_tck;
		printf("%um%u.%03us%c",
			sec / 60, sec % 60,
			(frac * 1000) / clk_tck,
			p[0]);
		p += 2;
	} while (*p);

	return EXIT_SUCCESS;
}
#endif

#if ENABLE_HUSH_MEMLEAK
static int FAST_FUNC builtin_memleak(char **argv UNUSED_PARAM)
{
	void *p;
	unsigned long l;

# ifdef M_TRIM_THRESHOLD
	/* Optional. Reduces probability of false positives */
	malloc_trim(0);
# endif
	/* Crude attempt to find where "free memory" starts,
	 * sans fragmentation. */
	p = malloc(240);
	l = (unsigned long)p;
	free(p);
	p = malloc(3400);
	if (l < (unsigned long)p) l = (unsigned long)p;
	free(p);


# if 0  /* debug */
	{
		struct mallinfo mi = mallinfo();
		printf("top alloc:0x%lx malloced:%d+%d=%d\n", l,
			mi.arena, mi.hblkhd, mi.arena + mi.hblkhd);
	}
# endif

	if (!G.memleak_value)
		G.memleak_value = l;

	l -= G.memleak_value;
	if ((long)l < 0)
		l = 0;
	l /= 1024;
	if (l > 127)
		l = 127;

	/* Exitcode is "how many kilobytes we leaked since 1st call" */
	return l;
}
#endif