ash.c

/* vi: set sw=4 ts=4: */
/*
 * ash shell port for busybox
 *
 * Copyright (c) 1989, 1991, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * This version of ash is adapted from the source in Debian's ash 0.3.8-5
 * package.
 *
 * Modified by Erik Andersen <andersee@debian.org> and
 * Vladimir Oleynik <vodz@usa.net> to be used in busybox
 *
 *
 * Original copyright notice is retained at the end of this file.
 */


/* These defines allow you to adjust the feature set to be compiled
 * into the ash shell.   As a rule, enabling these options will make
 * ash get bigger...   With all of these options off, ash adds about
 * 62k to busybox on an x86 system.*/



/* Enable job control.  This allows you to run jobs in the background,
 * which is great when ash is being  used as an interactive shell, but
 * it completely useless for is all you are doing is running scripts.  
 * This adds about 2.5k on an x86 system. */
#define JOBS

/* This enables alias support in ash.  If you want to support things
 * like "alias ls='ls -l'" with ash, enable this.  This is only useful
 * when ash is used as an intractive shell.   This adds about 1.5k */
#define ASH_ALIAS

/* If you need ash to act as a full Posix shell, with full math
 * support, enable this.   This option needs some work, since it
 * doesn't compile right now... */
#undef ASH_MATH_SUPPORT

/* This shell builtin is used to indicate how the shell would interpret
 * what you give it.  This command is only useful when debugging, and
 * is obsolete anyways.  Adds about 670 bytes... You probably want to
 * leave this disabled. */
#undef ASH_TYPE

/* Getopts is used by shell procedures to parse positional parameters.
 * You probably want to leave this disabled, and use the busybox getopt
 * applet if you want to do this sort of thing.  There are some scripts
 * out there that use it, so it you need it, enable.  Most people will
 * leave this disabled.  This adds 1k on an x86 system. */
#undef ASH_GETOPTS

/* This allows you to override shell builtins and use whatever is on
 * the filesystem.  This is most useful when ash is acting as a
 * standalone shell.   Adds about 320 bytes. */
#undef ASH_CMDCMD

/* This makes a few common apps that are usually part of busybox
 * anyways to be used as builtins.  This may cause these builtins to be
 * a little bit faster, but leaving this disabled will save you 2k. */
#undef ASH_BBAPPS_AS_BUILTINS

/* Enable this to compile in extra debugging noise.  When debugging is
 * on, debugging info will be written to $HOME/trace and a quit signal
 * will generate a core dump. */
#undef DEBUG



/* These are here to work with glibc -- Don't change these... */
#undef FNMATCH_BROKEN
#undef GLOB_BROKEN
#undef _GNU_SOURCE

#include <assert.h>
#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <paths.h>
#include <pwd.h>
#include <setjmp.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/cdefs.h>
#include <sys/ioctl.h>
#include <sys/param.h>
#include <sys/resource.h>
#include <sys/time.h>
#include <sys/times.h>
#include <sys/types.h>
#include <sys/wait.h>


#if !defined(FNMATCH_BROKEN)
#include <fnmatch.h>
#endif
#if !defined(GLOB_BROKEN)
#include <glob.h>
#endif

#ifdef JOBS
#include <termios.h>
#endif

#include "busybox.h"
#include "cmdedit.h"

/* if BB_PWD is defined, then disable ASH_PWD to save space */
#ifdef BB_PWD
#undef ASH_PWD
#endif


/*
 * This file was generated by the mksyntax program.
 */

/* Syntax classes */
#define CWORD 0                 /* character is nothing special */
#define CNL 1                   /* newline character */
#define CBACK 2                 /* a backslash character */
#define CSQUOTE 3               /* single quote */
#define CDQUOTE 4               /* double quote */
#define CENDQUOTE 5             /* a terminating quote */
#define CBQUOTE 6               /* backwards single quote */
#define CVAR 7                  /* a dollar sign */
#define CENDVAR 8               /* a '}' character */
#define CLP 9                   /* a left paren in arithmetic */
#define CRP 10                  /* a right paren in arithmetic */
#define CENDFILE 11             /* end of file */
#define CCTL 12                 /* like CWORD, except it must be escaped */
#define CSPCL 13                /* these terminate a word */
#define CIGN 14                 /* character should be ignored */

/* Syntax classes for is_ functions */
#define ISDIGIT 01              /* a digit */
#define ISUPPER 02              /* an upper case letter */
#define ISLOWER 04              /* a lower case letter */
#define ISUNDER 010             /* an underscore */
#define ISSPECL 020             /* the name of a special parameter */

#define SYNBASE 130
#define PEOF -130

#define PEOA -129

#define TEOF 0
#define TNL 1
#define TSEMI 2
#define TBACKGND 3
#define TAND 4
#define TOR 5
#define TPIPE 6
#define TLP 7
#define TRP 8
#define TENDCASE 9
#define TENDBQUOTE 10
#define TREDIR 11
#define TWORD 12
#define TASSIGN 13
#define TNOT 14
#define TCASE 15
#define TDO 16
#define TDONE 17
#define TELIF 18
#define TELSE 19
#define TESAC 20
#define TFI 21
#define TFOR 22
#define TIF 23
#define TIN 24
#define TTHEN 25
#define TUNTIL 26
#define TWHILE 27
#define TBEGIN 28
#define TEND 29


#define BASESYNTAX (basesyntax + SYNBASE)
#define DQSYNTAX (dqsyntax + SYNBASE)
#define SQSYNTAX (sqsyntax + SYNBASE)
#define ARISYNTAX (arisyntax + SYNBASE)

/* control characters in argument strings */
#define CTLESC '\201'
#define CTLVAR '\202'
#define CTLENDVAR '\203'
#define CTLBACKQ '\204'
#define CTLQUOTE 01             /* ored with CTLBACKQ code if in quotes */
/*      CTLBACKQ | CTLQUOTE == '\205' */
#define CTLARI  '\206'
#define CTLENDARI '\207'
#define CTLQUOTEMARK '\210'

#define is_digit(c)     ((((unsigned char)(c)) - '0') <= 9)
#define is_alpha(c)     (((c) < CTLESC || (c) > CTLENDARI) && isalpha((unsigned char) (c)))
#define is_name(c)      (((c) < CTLESC || (c) > CTLENDARI) && ((c) == '_' || isalpha((unsigned char) (c))))
#define is_in_name(c)   (((c) < CTLESC || (c) > CTLENDARI) && ((c) == '_' || isalnum((unsigned char) (c))))
#define is_special(c)   ((is_type+SYNBASE)[c] & (ISSPECL|ISDIGIT))
#define digit_val(c)    ((c) - '0')


#define _DIAGASSERT(x)

#define ATABSIZE 39

#define S_DFL 1                 /* default signal handling (SIG_DFL) */
#define S_CATCH 2               /* signal is caught */
#define S_IGN 3                 /* signal is ignored (SIG_IGN) */
#define S_HARD_IGN 4            /* signal is ignored permenantly */
#define S_RESET 5               /* temporary - to reset a hard ignored sig */


/* variable substitution byte (follows CTLVAR) */
#define VSTYPE  0x0f            /* type of variable substitution */
#define VSNUL   0x10            /* colon--treat the empty string as unset */
#define VSQUOTE 0x80            /* inside double quotes--suppress splitting */

/* values of VSTYPE field */
#define VSNORMAL        0x1             /* normal variable:  $var or ${var} */
#define VSMINUS         0x2             /* ${var-text} */
#define VSPLUS          0x3             /* ${var+text} */
#define VSQUESTION      0x4             /* ${var?message} */
#define VSASSIGN        0x5             /* ${var=text} */
#define VSTRIMLEFT      0x6             /* ${var#pattern} */
#define VSTRIMLEFTMAX   0x7             /* ${var##pattern} */
#define VSTRIMRIGHT     0x8             /* ${var%pattern} */
#define VSTRIMRIGHTMAX  0x9             /* ${var%%pattern} */
#define VSLENGTH        0xa             /* ${#var} */

/* flags passed to redirect */
#define REDIR_PUSH 01           /* save previous values of file descriptors */
#define REDIR_BACKQ 02          /* save the command output in memory */

/*
 * BSD setjmp saves the signal mask, which violates ANSI C and takes time,
 * so we use _setjmp instead.
 */

#if !defined(__GLIBC__)
#define setjmp(jmploc)  _setjmp(jmploc)
#define longjmp(jmploc, val)    _longjmp(jmploc, val)
#endif

/*
 * Most machines require the value returned from malloc to be aligned
 * in some way.  The following macro will get this right on many machines.
 */

#ifndef ALIGN
union align {
	int i;
	char *cp;
};

#define ALIGN(nbytes)   (((nbytes) + sizeof(union align) - 1) & ~(sizeof(union align) - 1))
#endif

#ifdef BB_LOCALE_SUPPORT
#include <locale.h>
static void change_lc_all(const char *value);
static void change_lc_ctype(const char *value);
#endif

/*
 * These macros allow the user to suspend the handling of interrupt signals
 * over a period of time.  This is similar to SIGHOLD to or sigblock, but
 * much more efficient and portable.  (But hacking the kernel is so much
 * more fun than worrying about efficiency and portability. :-))
 */

static void onint (void);
static volatile int suppressint;
static volatile int intpending;

#define INTOFF suppressint++
#ifdef ASH_BBAPPS_AS_BUILTINS
#define INTON { if (--suppressint == 0 && intpending) onint(); }
#else
static void __inton (void);
#define INTON __inton()
#endif
#define FORCEINTON {suppressint = 0; if (intpending) onint();}
#define CLEAR_PENDING_INT intpending = 0
#define int_pending() intpending


typedef void *pointer;
#ifndef NULL
#define NULL (void *)0
#endif

static inline pointer  ckmalloc (int sz)          { return xmalloc(sz);     }
static inline pointer  ckrealloc(void *p, int sz) { return xrealloc(p, sz); }
static inline char *   savestr  (const char *s)   { return xstrdup(s);      }

static pointer stalloc (int);
static void stunalloc (pointer);
static void ungrabstackstr (char *, char *);
static char * growstackstr(void);
static char *sstrdup (const char *);

/*
 * Parse trees for commands are allocated in lifo order, so we use a stack
 * to make this more efficient, and also to avoid all sorts of exception
 * handling code to handle interrupts in the middle of a parse.
 *
 * The size 504 was chosen because the Ultrix malloc handles that size
 * well.
 */

#define MINSIZE 504             /* minimum size of a block */


struct stack_block {
	struct stack_block *prev;
	char space[MINSIZE];
};

static struct stack_block stackbase;
static struct stack_block *stackp = &stackbase;
static struct stackmark *markp;
static char *stacknxt = stackbase.space;
static int stacknleft = MINSIZE;


#define equal(s1, s2)   (strcmp(s1, s2) == 0)

#define stackblock() stacknxt
#define stackblocksize() stacknleft
#define STARTSTACKSTR(p)        p = stackblock(), sstrnleft = stackblocksize()
#define STPUTC(c, p)    (--sstrnleft >= 0? (*p++ = (c)) : (p = growstackstr(), *p++ = (c)))
#define CHECKSTRSPACE(n, p)     { if (sstrnleft < n) p = makestrspace(n); }
#define USTPUTC(c, p)   (--sstrnleft, *p++ = (c))
#define STACKSTRNUL(p)  (sstrnleft == 0? (p = growstackstr(), *p = '\0') : (*p = '\0'))
#define STUNPUTC(p)     (++sstrnleft, --p)
#define STTOPC(p)       p[-1]
#define STADJUST(amount, p)     (p += (amount), sstrnleft -= (amount))
#define grabstackstr(p) stalloc(stackblocksize() - sstrnleft)

#define ckfree(p)       free((pointer)(p))

static char * makestrspace(size_t newlen);

#ifdef DEBUG
#define TRACE(param)    trace param
static void trace (const char *, ...);
static void trargs (char **);
static void showtree (union node *);
static void trputc (int);
static void trputs (const char *);
static void opentrace (void);
#else
#define TRACE(param)
#endif

#define NSEMI 0
#define NCMD 1
#define NPIPE 2
#define NREDIR 3
#define NBACKGND 4
#define NSUBSHELL 5
#define NAND 6
#define NOR 7
#define NIF 8
#define NWHILE 9
#define NUNTIL 10
#define NFOR 11
#define NCASE 12
#define NCLIST 13
#define NDEFUN 14
#define NARG 15
#define NTO 16
#define NFROM 17
#define NFROMTO 18
#define NAPPEND 19
#define NTOOV 20
#define NTOFD 21
#define NFROMFD 22
#define NHERE 23
#define NXHERE 24
#define NNOT 25

/*
 * expandarg() flags
 */
#define EXP_FULL        0x1     /* perform word splitting & file globbing */
#define EXP_TILDE       0x2     /* do normal tilde expansion */
#define EXP_VARTILDE    0x4     /* expand tildes in an assignment */
#define EXP_REDIR       0x8     /* file glob for a redirection (1 match only) */
#define EXP_CASE        0x10    /* keeps quotes around for CASE pattern */
#define EXP_RECORD      0x20    /* need to record arguments for ifs breakup */


#define NOPTS   16

static char optet_vals[NOPTS];

static const char * const optlist[NOPTS] = {
	"e" "errexit",
	"f" "noglob",
	"I" "ignoreeof",
	"i" "interactive",
	"m" "monitor",
	"n" "noexec",
	"s" "stdin",
	"x" "xtrace",
	"v" "verbose",
	"V" "vi",
	"E" "emacs",
	"C" "noclobber",
	"a" "allexport",
	"b" "notify",
	"u" "nounset",
	"q" "quietprofile"
};

#define optent_name(optent) (optent+1)
#define optent_letter(optent) optent[0]
#define optent_val(optent) optet_vals[optent]

#define eflag optent_val(0)
#define fflag optent_val(1)
#define Iflag optent_val(2)
#define iflag optent_val(3)
#define mflag optent_val(4)
#define nflag optent_val(5)
#define sflag optent_val(6)
#define xflag optent_val(7)
#define vflag optent_val(8)
#define Vflag optent_val(9)
#define Eflag optent_val(10)
#define Cflag optent_val(11)
#define aflag optent_val(12)
#define bflag optent_val(13)
#define uflag optent_val(14)
#define qflag optent_val(15)


/* Mode argument to forkshell.  Don't change FORK_FG or FORK_BG. */
#define FORK_FG 0
#define FORK_BG 1
#define FORK_NOJOB 2


struct nbinary {
      int type;
      union node *ch1;
      union node *ch2;
};


struct ncmd {
      int type;
      int backgnd;
      union node *assign;
      union node *args;
      union node *redirect;
};


struct npipe {
      int type;
      int backgnd;
      struct nodelist *cmdlist;
};


struct nredir {
      int type;
      union node *n;
      union node *redirect;
};


struct nif {
      int type;
      union node *test;
      union node *ifpart;
      union node *elsepart;
};


struct nfor {
      int type;
      union node *args;
      union node *body;
      char *var;
};


struct ncase {
      int type;
      union node *expr;
      union node *cases;
};


struct nclist {
      int type;
      union node *next;
      union node *pattern;
      union node *body;
};


struct narg {
      int type;
      union node *next;
      char *text;
      struct nodelist *backquote;
};


struct nfile {
      int type;
      union node *next;
      int fd;
      union node *fname;
      char *expfname;
};


struct ndup {
      int type;
      union node *next;
      int fd;
      int dupfd;
      union node *vname;
};


struct nhere {
      int type;
      union node *next;
      int fd;
      union node *doc;
};


struct nnot {
      int type;
      union node *com;
};


union node {
      int type;
      struct nbinary nbinary;
      struct ncmd ncmd;
      struct npipe npipe;
      struct nredir nredir;
      struct nif nif;
      struct nfor nfor;
      struct ncase ncase;
      struct nclist nclist;
      struct narg narg;
      struct nfile nfile;
      struct ndup ndup;
      struct nhere nhere;
      struct nnot nnot;
};


struct nodelist {
	struct nodelist *next;
	union node *n;
};

struct backcmd {                /* result of evalbackcmd */
	int fd;                 /* file descriptor to read from */
	char *buf;              /* buffer */
	int nleft;              /* number of chars in buffer */
	struct job *jp;         /* job structure for command */
};

struct cmdentry {
	int cmdtype;
	union param {
		int index;
		union node *func;
		const struct builtincmd *cmd;
	} u;
};

struct strlist {
	struct strlist *next;
	char *text;
};


struct arglist {
	struct strlist *list;
	struct strlist **lastp;
};

struct strpush {
	struct strpush *prev;   /* preceding string on stack */
	char *prevstring;
	int prevnleft;
#ifdef ASH_ALIAS
	struct alias *ap;       /* if push was associated with an alias */
#endif
	char *string;           /* remember the string since it may change */
};

struct parsefile {
	struct parsefile *prev; /* preceding file on stack */
	int linno;              /* current line */
	int fd;                 /* file descriptor (or -1 if string) */
	int nleft;              /* number of chars left in this line */
	int lleft;              /* number of chars left in this buffer */
	char *nextc;            /* next char in buffer */
	char *buf;              /* input buffer */
	struct strpush *strpush; /* for pushing strings at this level */
	struct strpush basestrpush; /* so pushing one is fast */
};

struct stackmark {
	struct stack_block *stackp;
	char *stacknxt;
	int stacknleft;
	struct stackmark *marknext;
};

struct shparam {
	int nparam;             /* # of positional parameters (without $0) */
	unsigned char malloc;   /* if parameter list dynamically allocated */
	char **p;               /* parameter list */
	int optind;             /* next parameter to be processed by getopts */
	int optoff;             /* used by getopts */
};

struct output {
#ifdef USE_GLIBC_STDIO
	FILE *stream;
#endif
	char *nextc;
	int nleft;
	char *buf;
	int bufsize;
	int fd;
	short flags;
};

#define OUTBUFSIZ BUFSIZ
#define MEM_OUT -3              /* output to dynamically allocated memory */


#ifdef USE_GLIBC_STDIO
static struct output output = {NULL, NULL, 0, NULL, 0, 1, 0};
static struct output errout = {NULL, NULL, 0, NULL, 0, 2, 0};
static struct output memout = {NULL, NULL, 0, NULL, 0, MEM_OUT, 0};
#else
static struct output output = {NULL, 0, NULL, OUTBUFSIZ, 1, 0};
static struct output errout = {NULL, 0, NULL, 0, 2, 0};
static struct output memout = {NULL, 0, NULL, 0, MEM_OUT, 0};
#endif
static struct output *out1 = &output;
static struct output *out2 = &errout;

#ifndef USE_GLIBC_STDIO
static void outcslow (char, struct output *);
#endif
static void flushall (void);
static void flushout (struct output *);
static void freestdout (void);
static void outfmt (struct output *, const char *, ...)
    __attribute__((__format__(__printf__,2,3)));
static void out1fmt (const char *, ...)
    __attribute__((__format__(__printf__,1,2)));
static void fmtstr (char *, size_t, const char *, ...)
    __attribute__((__format__(__printf__,3,4)));
#ifndef USE_GLIBC_STDIO
static void doformat (struct output *, const char *, va_list);
#endif
static int xwrite (int, const char *, int);
#ifdef USE_GLIBC_STDIO
static void initstreams (void);
static void openmemout (void);
static int __closememout (void);
#endif

static void outstr(const char *p, struct output *file);

#define OUTPUT_ERR 01           /* error occurred on output */

#ifdef USE_GLIBC_STDIO
#define outc(c, o)      putc((c), (o)->stream)
#define doformat(d, f, a)       vfprintf((d)->stream, (f), (a))
#else
#define outc(c, file)   (--(file)->nleft < 0? outcslow((c), (file)) : (*(file)->nextc = (c), (file)->nextc++))
#endif
#define out1c(c)        outc((c), out1)
#define out2c(c)        outc((c), out2)
#define out1str(s)      outstr((s), out1)
#define out2str(s)      outstr((s), out2)
#define outerr(f)       ((f)->flags & OUTPUT_ERR)

/* syntax table used when not in quotes */
static const char basesyntax[257] = {
      CENDFILE,   CSPCL,   CWORD,   CCTL,
      CCTL,    CCTL,    CCTL,    CCTL,
      CCTL,    CCTL,    CCTL,    CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CSPCL,
      CNL,     CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CSPCL,   CWORD,
      CDQUOTE, CWORD,   CVAR,    CWORD,
      CSPCL,   CSQUOTE, CSPCL,   CSPCL,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CSPCL,   CSPCL,   CWORD,
      CSPCL,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CBACK,   CWORD,
      CWORD,   CWORD,   CBQUOTE, CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CSPCL,   CENDVAR,
      CWORD
};

/* syntax table used when in double quotes */
static const char dqsyntax[257] = {
      CENDFILE,   CIGN,    CWORD,   CCTL,
      CCTL,    CCTL,    CCTL,    CCTL,
      CCTL,    CCTL,    CCTL,    CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CNL,     CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CCTL,
      CENDQUOTE,CWORD,  CVAR,    CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CCTL,    CWORD,   CWORD,   CCTL,
      CWORD,   CCTL,    CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CCTL,    CWORD,   CWORD,   CCTL,
      CWORD,   CCTL,    CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CCTL,    CBACK,   CCTL,
      CWORD,   CWORD,   CBQUOTE, CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CENDVAR,
      CCTL
};

/* syntax table used when in single quotes */
static const char sqsyntax[257] = {
      CENDFILE,   CIGN,    CWORD,   CCTL,
      CCTL,    CCTL,    CCTL,    CCTL,
      CCTL,    CCTL,    CCTL,    CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CNL,     CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CCTL,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CENDQUOTE,CWORD,  CWORD,
      CCTL,    CWORD,   CWORD,   CCTL,
      CWORD,   CCTL,    CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CCTL,    CWORD,   CWORD,   CCTL,
      CWORD,   CCTL,    CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CCTL,    CCTL,    CCTL,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CCTL
};

/* syntax table used when in arithmetic */
static const char arisyntax[257] = {
      CENDFILE,   CIGN,    CWORD,   CCTL,
      CCTL,    CCTL,    CCTL,    CCTL,
      CCTL,    CCTL,    CCTL,    CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CNL,     CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CDQUOTE, CWORD,   CVAR,    CWORD,
      CWORD,   CSQUOTE, CLP,     CRP,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CBACK,   CWORD,
      CWORD,   CWORD,   CBQUOTE, CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CWORD,
      CWORD,   CWORD,   CWORD,   CENDVAR,
      CWORD
};

/* character classification table */
static const char is_type[257] = {
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       0,
      0,       0,       0,       ISSPECL,
      0,       ISSPECL, ISSPECL, 0,
      0,       0,       0,       0,
      ISSPECL, 0,       0,       ISSPECL,
      0,       0,       ISDIGIT, ISDIGIT,
      ISDIGIT, ISDIGIT, ISDIGIT, ISDIGIT,
      ISDIGIT, ISDIGIT, ISDIGIT, ISDIGIT,
      0,       0,       0,       0,
      0,       ISSPECL, ISSPECL, ISUPPER,
      ISUPPER, ISUPPER, ISUPPER, ISUPPER,
      ISUPPER, ISUPPER, ISUPPER, ISUPPER,
      ISUPPER, ISUPPER, ISUPPER, ISUPPER,
      ISUPPER, ISUPPER, ISUPPER, ISUPPER,
      ISUPPER, ISUPPER, ISUPPER, ISUPPER,
      ISUPPER, ISUPPER, ISUPPER, ISUPPER,
      ISUPPER, 0,       0,       0,
      0,       ISUNDER, 0,       ISLOWER,
      ISLOWER, ISLOWER, ISLOWER, ISLOWER,
      ISLOWER, ISLOWER, ISLOWER, ISLOWER,
      ISLOWER, ISLOWER, ISLOWER, ISLOWER,
      ISLOWER, ISLOWER, ISLOWER, ISLOWER,
      ISLOWER, ISLOWER, ISLOWER, ISLOWER,
      ISLOWER, ISLOWER, ISLOWER, ISLOWER,
      ISLOWER, 0,       0,       0,
      0
};

/* Array indicating which tokens mark the end of a list */
static const char tokendlist[] = {
	1,
	0,
	0,
	0,
	0,
	0,
	0,
	0,
	1,
	1,
	1,
	0,
	0,
	0,
	0,
	0,
	1,
	1,
	1,
	1,
	1,
	1,
	0,
	0,
	0,
	1,
	0,
	0,
	0,
	1,
};

static const char *const tokname[] = {
	"end of file",
	"newline",
	"\";\"",
	"\"&\"",
	"\"&&\"",
	"\"||\"",
	"\"|\"",
	"\"(\"",
	"\")\"",
	"\";;\"",
	"\"`\"",
	"redirection",
	"word",
	"assignment",
	"\"!\"",
	"\"case\"",
	"\"do\"",
	"\"done\"",
	"\"elif\"",
	"\"else\"",
	"\"esac\"",
	"\"fi\"",
	"\"for\"",
	"\"if\"",
	"\"in\"",
	"\"then\"",
	"\"until\"",
	"\"while\"",
	"\"{\"",
	"\"}\"",
};

#define KWDOFFSET 14

static const char *const parsekwd[] = {
	"!",
	"case",
	"do",
	"done",
	"elif",
	"else",
	"esac",
	"fi",
	"for",
	"if",
	"in",
	"then",
	"until",
	"while",
	"{",
	"}"
};


static int plinno = 1;          /* input line number */

static int parselleft;          /* copy of parsefile->lleft */

static struct parsefile basepf; /* top level input file */
static char basebuf[BUFSIZ];    /* buffer for top level input file */
static struct parsefile *parsefile = &basepf;  /* current input file */

/*
 * NEOF is returned by parsecmd when it encounters an end of file.  It
 * must be distinct from NULL, so we use the address of a variable that
 * happens to be handy.
 */

static int tokpushback;         /* last token pushed back */
#define NEOF ((union node *)&tokpushback)
static int checkkwd;            /* 1 == check for kwds, 2 == also eat newlines */


static void error (const char *, ...) __attribute__((__noreturn__));
static void exerror (int, const char *, ...) __attribute__((__noreturn__));
static void shellexec (char **, char **, const char *, int)
    __attribute__((noreturn));
static void exitshell (int) __attribute__((noreturn));

static int  goodname(const char *);
static void ignoresig (int);
static void onsig (int);
static void dotrap (void);
static int  decode_signal (const char *, int);

static void shprocvar(void);
static void deletefuncs(void);
static void setparam (char **);
static void freeparam (volatile struct shparam *);

/* reasons for skipping commands (see comment on breakcmd routine) */
#define SKIPBREAK       1
#define SKIPCONT        2
#define SKIPFUNC        3
#define SKIPFILE        4

/* values of cmdtype */
#define CMDUNKNOWN -1           /* no entry in table for command */
#define CMDNORMAL 0             /* command is an executable program */
#define CMDBUILTIN 1            /* command is a shell builtin */
#define CMDFUNCTION 2           /* command is a shell function */

#define DO_ERR  1               /* find_command prints errors */
#define DO_ABS  2               /* find_command checks absolute paths */
#define DO_NOFUN        4       /* find_command ignores functions */
#define DO_BRUTE        8       /* find_command ignores hash table */

/*
 * Shell variables.
 */

/* flags */
#define VEXPORT         0x01    /* variable is exported */
#define VREADONLY       0x02    /* variable cannot be modified */
#define VSTRFIXED       0x04    /* variable struct is staticly allocated */
#define VTEXTFIXED      0x08    /* text is staticly allocated */
#define VSTACK          0x10    /* text is allocated on the stack */
#define VUNSET          0x20    /* the variable is not set */
#define VNOFUNC         0x40    /* don't call the callback function */


struct var {
	struct var *next;               /* next entry in hash list */
	int flags;                      /* flags are defined above */
	char *text;                     /* name=value */
	void (*func) (const char *);
					/* function to be called when  */
					/* the variable gets set/unset */
};

struct localvar {
	struct localvar *next;          /* next local variable in list */
	struct var *vp;                 /* the variable that was made local */
	int flags;                      /* saved flags */
	char *text;                     /* saved text */
};


#if defined(__GLIBC__) && !defined(FNMATCH_BROKEN)
#define rmescapes(p) _rmescapes((p), 0)
static char *_rmescapes (char *, int);
#else
static void rmescapes (char *);
#endif

static int  casematch (union node *, const char *);
static void clearredir(void);
static void popstring(void);
static void readcmdfile (const char *);

static int number (const char *);
static int is_number (const char *, int *num);
static char *single_quote (const char *);
static int nextopt (const char *);

static void redirect (union node *, int);
static void popredir (void);
static int dup_as_newfd (int, int);

static void changepath(const char *newval);
static void getoptsreset(const char *value);


static int parsenleft;                  /* copy of parsefile->nleft */
static char *parsenextc;                /* copy of parsefile->nextc */
static int rootpid;     /* pid of main shell */
static int rootshell;   /* true if we aren't a child of the main shell */

static const char spcstr[] = " ";
static const char snlfmt[] = "%s\n";

static int sstrnleft;
static int herefd = -1;

static struct localvar *localvars;

static struct var vifs;
static struct var vmail;
static struct var vmpath;
static struct var vpath;
static struct var vps1;
static struct var vps2;
static struct var voptind;
#ifdef BB_LOCALE_SUPPORT
static struct var vlc_all;
static struct var vlc_ctype;
#endif

struct varinit {
	struct var *var;
	int flags;
	const char *text;
	void (*func) (const char *);
};

static const char defpathvar[] =
	"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin";
#define defpath (defpathvar + 5)

#ifdef IFS_BROKEN
static const char defifsvar[] = "IFS= \t\n";
#define defifs (defifsvar + 4)
#else
static const char defifs[] = " \t\n";
#endif

static const struct varinit varinit[] = {
#ifdef IFS_BROKEN
	{ &vifs,        VSTRFIXED|VTEXTFIXED,           defifsvar,
#else
	{ &vifs,        VSTRFIXED|VTEXTFIXED|VUNSET,    "IFS=",
#endif
	  NULL },
	{ &vmail,       VSTRFIXED|VTEXTFIXED|VUNSET,    "MAIL=",
	  NULL },
	{ &vmpath,      VSTRFIXED|VTEXTFIXED|VUNSET,    "MAILPATH=",
	  NULL },
	{ &vpath,       VSTRFIXED|VTEXTFIXED,           defpathvar,
	  changepath },
	/*
	 * vps1 depends on uid
	 */
	{ &vps2,        VSTRFIXED|VTEXTFIXED,           "PS2=> ",
	  NULL },
	{ &voptind,     VSTRFIXED|VTEXTFIXED,           "OPTIND=1",
	  getoptsreset },
#ifdef BB_LOCALE_SUPPORT
	{ &vlc_all,     VSTRFIXED|VTEXTFIXED|VUNSET,    "LC_ALL=",
	  change_lc_all },
	{ &vlc_ctype,   VSTRFIXED|VTEXTFIXED|VUNSET,    "LC_CTYPE=",
	  change_lc_ctype },
#endif
	{ NULL, 0,                              NULL,
	  NULL }
};

#define VTABSIZE 39

static struct var *vartab[VTABSIZE];

/*
 * The following macros access the values of the above variables.
 * They have to skip over the name.  They return the null string
 * for unset variables.
 */

#define ifsval()        (vifs.text + 4)
#define ifsset()        ((vifs.flags & VUNSET) == 0)
#define mailval()       (vmail.text + 5)
#define mpathval()      (vmpath.text + 9)
#define pathval()       (vpath.text + 5)
#define ps1val()        (vps1.text + 4)
#define ps2val()        (vps2.text + 4)
#define optindval()     (voptind.text + 7)

#define mpathset()      ((vmpath.flags & VUNSET) == 0)

static void initvar (void);
static void setvar (const char *, const char *, int);
static void setvareq (char *, int);
static void listsetvar (struct strlist *);
static char *lookupvar (const char *);
static char *bltinlookup (const char *);
static char **environment (void);
static int showvarscmd (int, char **);
static void mklocal (char *);
static void poplocalvars (void);
static int unsetvar (const char *);
static int varequal (const char *, const char *);


static char *arg0;                      /* value of $0 */
static struct shparam shellparam;       /* current positional parameters */
static char **argptr;                   /* argument list for builtin commands */
static char *optionarg;                 /* set by nextopt (like getopt) */
static char *optptr;                    /* used by nextopt */
static char *minusc;                    /* argument to -c option */


#ifdef ASH_ALIAS

#define ALIASINUSE      1
#define ALIASDEAD       2

struct alias {
	struct alias *next;
	char *name;
	char *val;
	int flag;
};

static struct alias *atab[ATABSIZE];

static void setalias (char *, char *);
static struct alias **hashalias (const char *);
static struct alias *freealias (struct alias *);
static struct alias **__lookupalias (const char *);

static void
setalias(name, val)
	char *name, *val;
{
	struct alias *ap, **app;

	app = __lookupalias(name);
	ap = *app;
	INTOFF;
	if (ap) {
		if (!(ap->flag & ALIASINUSE)) {
			ckfree(ap->val);
		}
		ap->val = savestr(val);
		ap->flag &= ~ALIASDEAD;
	} else {
		/* not found */
		ap = ckmalloc(sizeof (struct alias));
		ap->name = savestr(name);
		ap->val = savestr(val);
		ap->flag = 0;
		ap->next = 0;
		*app = ap;
	}
	INTON;
}

static int
unalias(char *name)
{
	struct alias **app;

	app = __lookupalias(name);

	if (*app) {
		INTOFF;
		*app = freealias(*app);
		INTON;
		return (0);
	}

	return (1);
}

static void
rmaliases(void)
{
	struct alias *ap, **app;
	int i;

	INTOFF;
	for (i = 0; i < ATABSIZE; i++) {
		app = &atab[i];
		for (ap = *app; ap; ap = *app) {
			*app = freealias(*app);
			if (ap == *app) {
				app = &ap->next;
			}
		}
	}
	INTON;
}

static struct alias *
lookupalias(const char *name, int check)
{
	struct alias *ap = *__lookupalias(name);

	if (check && ap && (ap->flag & ALIASINUSE))
		return (NULL);
	return (ap);
}

static void
printalias(const struct alias *ap) {
	char *p;

	p = single_quote(ap->val);
	out1fmt("alias %s=%s\n", ap->name, p);
	stunalloc(p);
}


/*
 * TODO - sort output
 */
static int
aliascmd(int argc, char **argv)
{
	char *n, *v;
	int ret = 0;
	struct alias *ap;

	if (argc == 1) {
		int i;

		for (i = 0; i < ATABSIZE; i++)
			for (ap = atab[i]; ap; ap = ap->next) {
				printalias(ap);
			}
		return (0);
	}
	while ((n = *++argv) != NULL) {
		if ((v = strchr(n+1, '=')) == NULL) { /* n+1: funny ksh stuff */
			if ((ap = *__lookupalias(n)) == NULL) {
				outfmt(out2, "%s: %s not found\n", "alias", n);
				ret = 1;
			} else
				printalias(ap);
		}
		else {
			*v++ = '\0';
			setalias(n, v);
		}
	}

	return (ret);
}

static int
unaliascmd(int argc, char **argv)
{
	int i;

	while ((i = nextopt("a")) != '\0') {
		if (i == 'a') {
			rmaliases();
			return (0);
		}
	}
	for (i = 0; *argptr; argptr++) {
		if (unalias(*argptr)) {
			outfmt(out2, "%s: %s not found\n", "unalias", *argptr);
			i = 1;
		}
	}

	return (i);
}

static struct alias **
hashalias(p)
	const char *p;
	{
	unsigned int hashval;

	hashval = *p << 4;
	while (*p)
		hashval+= *p++;
	return &atab[hashval % ATABSIZE];
}

static struct alias *
freealias(struct alias *ap) {
	struct alias *next;

	if (ap->flag & ALIASINUSE) {
		ap->flag |= ALIASDEAD;
		return ap;
	}

	next = ap->next;
	ckfree(ap->name);
	ckfree(ap->val);
	ckfree(ap);
	return next;
}


static struct alias **
__lookupalias(const char *name) {
	struct alias **app = hashalias(name);

	for (; *app; app = &(*app)->next) {
		if (equal(name, (*app)->name)) {
			break;
		}
	}

	return app;
}
#endif

#ifdef ASH_MATH_SUPPORT
/* The generated file arith.c has been snipped.  If you want this
 * stuff back in, feel free to add it to your own copy.  */
#define ARITH_NUM 257
#define ARITH_LPAREN 258
#define ARITH_RPAREN 259
#define ARITH_OR 260
#define ARITH_AND 261
#define ARITH_BOR 262
#define ARITH_BXOR 263
#define ARITH_BAND 264
#define ARITH_EQ 265
#define ARITH_NE 266
#define ARITH_LT 267
#define ARITH_GT 268
#define ARITH_GE 269
#define ARITH_LE 270
#define ARITH_LSHIFT 271
#define ARITH_RSHIFT 272
#define ARITH_ADD 273
#define ARITH_SUB 274
#define ARITH_MUL 275
#define ARITH_DIV 276
#define ARITH_REM 277
#define ARITH_UNARYMINUS 278
#define ARITH_UNARYPLUS 279
#define ARITH_NOT 280
#define ARITH_BNOT 281

static void expari (int);
/* From arith.y */
static int arith (const char *);
static int expcmd (int , char **);
static void arith_lex_reset (void);
static int yylex (void);

#endif

static char *trap[NSIG];                /* trap handler commands */
static char sigmode[NSIG - 1];  /* current value of signal */
static char gotsig[NSIG - 1];           /* indicates specified signal received */
static int pendingsigs;                 /* indicates some signal received */

/*
 * This file was generated by the mkbuiltins program.
 */

#ifdef JOBS
static int bgcmd (int, char **);
static int fgcmd (int, char **);
static int killcmd (int, char **);
#endif
#ifdef ASH_BBAPPS_AS_BUILTINS
static int bltincmd (int, char **);
#endif
static int cdcmd (int, char **);
static int breakcmd (int, char **);
#ifdef ASH_CMDCMD
static int commandcmd (int, char **);
#endif
static int dotcmd (int, char **);
static int evalcmd (int, char **);
static int execcmd (int, char **);
static int exitcmd (int, char **);
static int exportcmd (int, char **);
static int histcmd (int, char **);
static int hashcmd (int, char **);
static int jobscmd (int, char **);
static int localcmd (int, char **);
#ifdef ASH_PWD
static int pwdcmd (int, char **);
#endif
static int readcmd (int, char **);
static int returncmd (int, char **);
static int setcmd (int, char **);
static int setvarcmd (int, char **);
static int shiftcmd (int, char **);
static int trapcmd (int, char **);
static int umaskcmd (int, char **);
#ifdef ASH_ALIAS
static int aliascmd (int, char **);
static int unaliascmd (int, char **);
#endif
static int unsetcmd (int, char **);
static int waitcmd (int, char **);
static int ulimitcmd (int, char **);
static int timescmd (int, char **);
#ifdef ASH_MATH_SUPPORT
static int expcmd (int, char **);
#endif
#ifdef ASH_TYPE
static int typecmd (int, char **);
#endif
#ifdef ASH_GETOPTS
static int getoptscmd (int, char **);
#endif

#ifndef BB_TRUE_FALSE
# ifdef ASH_BBAPPS_AS_BUILTINS
static int true_main (int, char **);
static int false_main (int, char **);
# endif
#endif

static void     setpwd (const char *, int);


#define BUILTIN_NOSPEC  "0"
#define BUILTIN_SPECIAL "1"
#define BUILTIN_REGULAR "2"
#define BUILTIN_ASSIGN  "4"
#define BUILTIN_SPEC_ASSG  "5"
#define BUILTIN_REG_ASSG   "6"

#define IS_BUILTIN_SPECIAL(builtincmd) ((builtincmd)->name[0] & 1)
#define IS_BUILTIN_REGULAR(builtincmd) ((builtincmd)->name[0] & 2)
#define IS_BUILTIN_ASSIGN(builtincmd) ((builtincmd)->name[0] & 4)

struct builtincmd {
	const char *name;
	int (*const builtinfunc) (int, char **);
	//unsigned flags;
};


/* It is CRUCIAL that this listing be kept in ascii order, otherwise
 * the binary search in find_builtin() will stop working. If you value
 * your kneecaps, you'll be sure to *make sure* that any changes made
 * to this array result in the listing remaining in ascii order. You
 * have been warned.
 */
static const struct builtincmd builtincmds[] = {
	{ BUILTIN_SPECIAL   ".", dotcmd },
	{ BUILTIN_SPECIAL   ":", true_main },
#ifdef ASH_ALIAS
	{ BUILTIN_REG_ASSG  "alias", aliascmd },
#endif
#ifdef JOBS
	{ BUILTIN_REGULAR   "bg", bgcmd },
#endif
	{ BUILTIN_SPECIAL   "break", breakcmd },
#ifdef ASH_BBAPPS_AS_BUILTINS
	{ BUILTIN_SPECIAL   "builtin", bltincmd },
#endif
	{ BUILTIN_REGULAR   "cd", cdcmd },
#ifdef ASH_BBAPPS_AS_BUILTINS
	{ BUILTIN_NOSPEC    "chdir", cdcmd },
#endif
#ifdef ASH_CMDCMD
	{ BUILTIN_REGULAR   "command", commandcmd },
#endif
	{ BUILTIN_SPECIAL   "continue", breakcmd },
	{ BUILTIN_SPECIAL   "eval", evalcmd },
	{ BUILTIN_SPECIAL   "exec", execcmd },
	{ BUILTIN_SPECIAL   "exit", exitcmd },
#ifdef ASH_MATH_SUPPORT
	{ BUILTIN_NOSPEC    "exp", expcmd },
#endif
	{ BUILTIN_SPEC_ASSG "export", exportcmd },
#ifdef ASH_BBAPPS_AS_BUILTINS
	{ BUILTIN_REGULAR   "false", false_main },
#endif
	{ BUILTIN_REGULAR   "fc", histcmd },
#ifdef JOBS
	{ BUILTIN_REGULAR   "fg", fgcmd },
#endif
#ifdef ASH_GETOPTS
	{ BUILTIN_REGULAR   "getopts", getoptscmd },
#endif
	{ BUILTIN_NOSPEC    "hash", hashcmd },
	{ BUILTIN_REGULAR   "jobs", jobscmd },
#ifdef JOBS
	{ BUILTIN_REGULAR   "kill", killcmd },
#endif
#ifdef ASH_MATH_SUPPORT
	{ BUILTIN_NOSPEC    "let", expcmd },
#endif
	{ BUILTIN_ASSIGN    "local", localcmd },
#ifdef ASH_PWD
	{ BUILTIN_NOSPEC    "pwd", pwdcmd },
#endif
	{ BUILTIN_REGULAR   "read", readcmd },
	{ BUILTIN_SPEC_ASSG "readonly", exportcmd },
	{ BUILTIN_SPECIAL   "return", returncmd },
	{ BUILTIN_SPECIAL   "set", setcmd },
	{ BUILTIN_NOSPEC    "setvar", setvarcmd },
	{ BUILTIN_SPECIAL   "shift", shiftcmd },
	{ BUILTIN_SPECIAL   "times", timescmd },
	{ BUILTIN_SPECIAL   "trap", trapcmd },
#ifdef ASH_BBAPPS_AS_BUILTINS
	{ BUILTIN_REGULAR   "true", true_main },
#endif
#ifdef ASH_TYPE
	{ BUILTIN_NOSPEC    "type", typecmd },
#endif
	{ BUILTIN_NOSPEC    "ulimit", ulimitcmd },
	{ BUILTIN_REGULAR   "umask", umaskcmd },
#ifdef ASH_ALIAS
	{ BUILTIN_REGULAR   "unalias", unaliascmd },
#endif
	{ BUILTIN_SPECIAL   "unset", unsetcmd },
	{ BUILTIN_REGULAR   "wait", waitcmd },
};
#define NUMBUILTINS  (sizeof (builtincmds) / sizeof (struct builtincmd) )

static const struct builtincmd *DOTCMD = &builtincmds[0];
static struct builtincmd *BLTINCMD;
static struct builtincmd *EXECCMD;
static struct builtincmd *EVALCMD;

/* states */
#define JOBSTOPPED 1            /* all procs are stopped */
#define JOBDONE 2               /* all procs are completed */

/*
 * A job structure contains information about a job.  A job is either a
 * single process or a set of processes contained in a pipeline.  In the
 * latter case, pidlist will be non-NULL, and will point to a -1 terminated
 * array of pids.
 */

struct procstat {
	pid_t pid;              /* process id */
	int status;             /* status flags (defined above) */
	char *cmd;              /* text of command being run */
};


static int job_warning;         /* user was warned about stopped jobs */

#ifdef JOBS
static void setjobctl(int enable);
#else
#define setjobctl(on)   /* do nothing */
#endif


struct job {
	struct procstat ps0;    /* status of process */
	struct procstat *ps;    /* status or processes when more than one */
	short nprocs;           /* number of processes */
	short pgrp;             /* process group of this job */
	char state;             /* true if job is finished */
	char used;              /* true if this entry is in used */
	char changed;           /* true if status has changed */
#ifdef JOBS
	char jobctl;            /* job running under job control */
#endif
};

static struct job *jobtab;      /* array of jobs */
static int njobs;               /* size of array */
static int backgndpid = -1;     /* pid of last background process */
#ifdef JOBS
static int initialpgrp;         /* pgrp of shell on invocation */
static int curjob;              /* current job */
static int jobctl;
#endif
static int intreceived;

static struct job *makejob (union node *, int);
static int forkshell (struct job *, union node *, int);
static int waitforjob (struct job *);

static int docd (char *, int);
static char *getcomponent (void);
static void updatepwd (const char *);
static void getpwd (void);

static char *padvance (const char **, const char *);

static char nullstr[1];         /* zero length string */
static char *curdir = nullstr;          /* current working directory */
static char *cdcomppath;

static int
cdcmd(argc, argv)
	int argc;
	char **argv;
{
	const char *dest;
	const char *path;
	char *p;
	struct stat statb;
	int print = 0;

	nextopt(nullstr);
	if ((dest = *argptr) == NULL && (dest = bltinlookup("HOME")) == NULL)
		error("HOME not set");
	if (*dest == '\0')
		dest = ".";
	if (dest[0] == '-' && dest[1] == '\0') {
		dest = bltinlookup("OLDPWD");
		if (!dest || !*dest) {
			dest = curdir;
		}
		print = 1;
		if (dest)
			print = 1;
		else
			dest = ".";
	}
	if (*dest == '/' || (path = bltinlookup("CDPATH")) == NULL)
		path = nullstr;
	while ((p = padvance(&path, dest)) != NULL) {
		if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) {
			if (!print) {
				/*
				 * XXX - rethink
				 */
				if (p[0] == '.' && p[1] == '/' && p[2] != '\0')
					p += 2;
				print = strcmp(p, dest);
			}
			if (docd(p, print) >= 0)
				return 0;

		}
	}
	error("can't cd to %s", dest);
	/* NOTREACHED */
}


/*
 * Actually do the chdir.  In an interactive shell, print the
 * directory name if "print" is nonzero.
 */

static int
docd(dest, print)
	char *dest;
	int print;
{
	char *p;
	char *q;
	char *component;
	struct stat statb;
	int first;
	int badstat;

	TRACE(("docd(\"%s\", %d) called\n", dest, print));

	/*
	 *  Check each component of the path. If we find a symlink or
	 *  something we can't stat, clear curdir to force a getcwd()
	 *  next time we get the value of the current directory.
	 */
	badstat = 0;
	cdcomppath = sstrdup(dest);
	STARTSTACKSTR(p);
	if (*dest == '/') {
		STPUTC('/', p);
		cdcomppath++;
	}
	first = 1;
	while ((q = getcomponent()) != NULL) {
		if (q[0] == '\0' || (q[0] == '.' && q[1] == '\0'))
			continue;
		if (! first)
			STPUTC('/', p);
		first = 0;
		component = q;
		while (*q)
			STPUTC(*q++, p);
		if (equal(component, ".."))
			continue;
		STACKSTRNUL(p);
		if ((lstat(stackblock(), &statb) < 0)
		    || (S_ISLNK(statb.st_mode)))  {
			/* print = 1; */
			badstat = 1;
			break;
		}
	}

	INTOFF;
	if (chdir(dest) < 0) {
		INTON;
		return -1;
	}
	updatepwd(badstat ? NULL : dest);
	INTON;
	if (print && iflag)
		out1fmt(snlfmt, curdir);
	return 0;
}


/*
 * Get the next component of the path name pointed to by cdcomppath.
 * This routine overwrites the string pointed to by cdcomppath.
 */

static char *
getcomponent() {
	char *p;
	char *start;

	if ((p = cdcomppath) == NULL)
		return NULL;
	start = cdcomppath;
	while (*p != '/' && *p != '\0')
		p++;
	if (*p == '\0') {
		cdcomppath = NULL;
	} else {
		*p++ = '\0';
		cdcomppath = p;
	}
	return start;
}



/*
 * Update curdir (the name of the current directory) in response to a
 * cd command.  We also call hashcd to let the routines in exec.c know
 * that the current directory has changed.
 */

static void hashcd (void);

static void
updatepwd(const char *dir)
{
	char *new;
	char *p;
	size_t len;

	hashcd();                               /* update command hash table */

	/*
	 * If our argument is NULL, we don't know the current directory
	 * any more because we traversed a symbolic link or something
	 * we couldn't stat().
	 */
	if (dir == NULL || curdir == nullstr)  {
		setpwd(0, 1);
		return;
	}
	len = strlen(dir);
	cdcomppath = sstrdup(dir);
	STARTSTACKSTR(new);
	if (*dir != '/') {
		p = curdir;
		while (*p)
			STPUTC(*p++, new);
		if (p[-1] == '/')
			STUNPUTC(new);
	}
	while ((p = getcomponent()) != NULL) {
		if (equal(p, "..")) {
			while (new > stackblock() && (STUNPUTC(new), *new) != '/');
		} else if (*p != '\0' && ! equal(p, ".")) {
			STPUTC('/', new);
			while (*p)
				STPUTC(*p++, new);
		}
	}
	if (new == stackblock())
		STPUTC('/', new);
	STACKSTRNUL(new);
	setpwd(stackblock(), 1);
}


#ifdef ASH_PWD
static int
pwdcmd(argc, argv)
	int argc;
	char **argv;
{
	out1fmt(snlfmt, curdir);
	return 0;
}
#endif

/*
 * Find out what the current directory is. If we already know the current
 * directory, this routine returns immediately.
 */
static void
getpwd(void)
{
	curdir = xgetcwd(0);
	if(curdir==0)
		curdir = nullstr;
}

static void
setpwd(const char *val, int setold)
{
	if (setold) {
		setvar("OLDPWD", curdir, VEXPORT);
	}
	INTOFF;
	if (curdir != nullstr) {
		free(curdir);
		curdir = nullstr;
	}
	if (!val) {
		getpwd();
	} else {
		curdir = savestr(val);
	}
	INTON;
	setvar("PWD", curdir, VEXPORT);
}

/*
 * Errors and exceptions.
 */

/*
 * Code to handle exceptions in C.
 */

/*
 * We enclose jmp_buf in a structure so that we can declare pointers to
 * jump locations.  The global variable handler contains the location to
 * jump to when an exception occurs, and the global variable exception
 * contains a code identifying the exeception.  To implement nested
 * exception handlers, the user should save the value of handler on entry
 * to an inner scope, set handler to point to a jmploc structure for the
 * inner scope, and restore handler on exit from the scope.
 */

struct jmploc {
	jmp_buf loc;
};

/* exceptions */
#define EXINT 0         /* SIGINT received */
#define EXERROR 1       /* a generic error */
#define EXSHELLPROC 2   /* execute a shell procedure */
#define EXEXEC 3        /* command execution failed */

static struct jmploc *handler;
static int exception;

static void exverror (int, const char *, va_list)
    __attribute__((__noreturn__));

/*
 * Called to raise an exception.  Since C doesn't include exceptions, we
 * just do a longjmp to the exception handler.  The type of exception is
 * stored in the global variable "exception".
 */

static void exraise (int) __attribute__((__noreturn__));

static void
exraise(int e)
{
#ifdef DEBUG
	if (handler == NULL)
		abort();
#endif
	exception = e;
	longjmp(handler->loc, 1);
}


/*
 * Called from trap.c when a SIGINT is received.  (If the user specifies
 * that SIGINT is to be trapped or ignored using the trap builtin, then
 * this routine is not called.)  Suppressint is nonzero when interrupts
 * are held using the INTOFF macro.  The call to _exit is necessary because
 * there is a short period after a fork before the signal handlers are
 * set to the appropriate value for the child.  (The test for iflag is
 * just defensive programming.)
 */

static void
onint(void) {
	sigset_t mysigset;

	if (suppressint) {
		intpending++;
		return;
	}
	intpending = 0;
	sigemptyset(&mysigset);
	sigprocmask(SIG_SETMASK, &mysigset, NULL);
	if (rootshell && iflag)
		exraise(EXINT);
	else {
		signal(SIGINT, SIG_DFL);
		raise(SIGINT);
	}
	/* NOTREACHED */
}


static char *commandname;       /* currently executing command */

/*
 * Exverror is called to raise the error exception.  If the first argument
 * is not NULL then error prints an error message using printf style
 * formatting.  It then raises the error exception.
 */
static void
exverror(int cond, const char *msg, va_list ap)
{
	CLEAR_PENDING_INT;
	INTOFF;

#ifdef DEBUG
	if (msg)
		TRACE(("exverror(%d, \"%s\") pid=%d\n", cond, msg, getpid()));
	else
		TRACE(("exverror(%d, NULL) pid=%d\n", cond, getpid()));
#endif
	if (msg) {
		if (commandname)
			outfmt(&errout, "%s: ", commandname);
		doformat(&errout, msg, ap);
#if FLUSHERR
		outc('\n', &errout);
#else
		outcslow('\n', &errout);
#endif
	}
	flushall();
	exraise(cond);
	/* NOTREACHED */
}


#ifdef __STDC__
static void
error(const char *msg, ...)
#else
static void
error(va_alist)
	va_dcl
#endif
{
#ifndef __STDC__
	const char *msg;
#endif
	va_list ap;
#ifdef __STDC__
	va_start(ap, msg);
#else
	va_start(ap);
	msg = va_arg(ap, const char *);
#endif
	exverror(EXERROR, msg, ap);
	/* NOTREACHED */
	va_end(ap);
}


#ifdef __STDC__
static void
exerror(int cond, const char *msg, ...)
#else
static void
exerror(va_alist)
	va_dcl
#endif
{
#ifndef __STDC__
	int cond;
	const char *msg;
#endif
	va_list ap;
#ifdef __STDC__
	va_start(ap, msg);
#else
	va_start(ap);
	cond = va_arg(ap, int);
	msg = va_arg(ap, const char *);
#endif
	exverror(cond, msg, ap);
	/* NOTREACHED */
	va_end(ap);
}



/*
 * Table of error messages.
 */

struct errname {
	short errcode;          /* error number */
	short action;           /* operation which encountered the error */
};

/*
 * Types of operations (passed to the errmsg routine).
 */

#define E_OPEN 01       /* opening a file */
#define E_CREAT 02      /* creating a file */
#define E_EXEC 04       /* executing a program */

#define ALL (E_OPEN|E_CREAT|E_EXEC)

static const struct errname errormsg[] = {
	{ EINTR,        ALL     },
	{ EACCES,       ALL     },
	{ EIO,          ALL     },
	{ ENOENT,       E_OPEN  },
	{ ENOENT,       E_CREAT },
	{ ENOENT,       E_EXEC  },
	{ ENOTDIR,      E_OPEN  },
	{ ENOTDIR,      E_CREAT },
	{ ENOTDIR,      E_EXEC  },
	{ EISDIR,       ALL     },
	{ EEXIST,       E_CREAT },
#ifdef EMFILE
	{ EMFILE,       ALL     },
#endif
	{ ENFILE,       ALL     },
	{ ENOSPC,       ALL     },
#ifdef EDQUOT
	{ EDQUOT,       ALL     },
#endif
#ifdef ENOSR
	{ ENOSR,        ALL     },
#endif
	{ ENXIO,        ALL     },
	{ EROFS,        ALL     },
	{ ETXTBSY,      ALL     },
#ifdef EAGAIN
	{ EAGAIN,       E_EXEC  },
#endif
	{ ENOMEM,       ALL     },
#ifdef ENOLINK
	{ ENOLINK,      ALL     },
#endif
#ifdef EMULTIHOP
	{ EMULTIHOP,    ALL     },
#endif
#ifdef ECOMM
	{ ECOMM,        ALL     },
#endif
#ifdef ESTALE
	{ ESTALE,       ALL     },
#endif
#ifdef ETIMEDOUT
	{ ETIMEDOUT,    ALL     },
#endif
#ifdef ELOOP
	{ ELOOP,        ALL     },
#endif
	{ E2BIG,        E_EXEC  },
#ifdef ELIBACC
	{ ELIBACC,      E_EXEC  },
#endif
};

#define ERRNAME_SIZE (sizeof(errormsg)/sizeof(struct errname))

/*
 * Return a string describing an error.  The returned string may be a
 * pointer to a static buffer that will be overwritten on the next call.
 * Action describes the operation that got the error.
 */

static const char *
errmsg(int e, int action)
{
	struct errname const *ep;
	static char buf[12];

	for (ep = errormsg ; ep < errormsg+ERRNAME_SIZE; ep++) {
		if (ep->errcode == e && (ep->action & action) != 0)
			return strerror(e);
	}

	fmtstr(buf, sizeof buf, "error %d", e);
	return buf;
}


#ifndef ASH_BBAPPS_AS_BUILTINS
static void
__inton() {
	if (--suppressint == 0 && intpending) {
		onint();
	}
}
#endif

/* flags in argument to evaltree */
#define EV_EXIT 01              /* exit after evaluating tree */
#define EV_TESTED 02            /* exit status is checked; ignore -e flag */
#define EV_BACKCMD 04           /* command executing within back quotes */

static int evalskip;                    /* set if we are skipping commands */
static int skipcount;           /* number of levels to skip */
static int loopnest;            /* current loop nesting level */
static int funcnest;                    /* depth of function calls */



static struct strlist *cmdenviron;      /* environment for builtin command */
static int exitstatus;                  /* exit status of last command */
static int oexitstatus;         /* saved exit status */


static void evalloop (union node *, int);
static void evalfor (union node *, int);
static void evalcase (union node *, int);
static void evalsubshell (union node *, int);
static void expredir (union node *);
static void evalpipe (union node *);
#ifdef notyet
static void evalcommand (union node *, int, struct backcmd *);
#else
static void evalcommand (union node *, int);
#endif
static void prehash (union node *);
static void eprintlist (struct strlist *);

static union node *parsecmd(int);
/*
 * Called to reset things after an exception.
 */

/*
 * The eval commmand.
 */
static void evalstring (char *, int);

static int
evalcmd(argc, argv)
	int argc;
	char **argv;
{
	char *p;
	char *concat;
	char **ap;

	if (argc > 1) {
		p = argv[1];
		if (argc > 2) {
			STARTSTACKSTR(concat);
			ap = argv + 2;
			for (;;) {
				while (*p)
					STPUTC(*p++, concat);
				if ((p = *ap++) == NULL)
					break;
				STPUTC(' ', concat);
			}
			STPUTC('\0', concat);
			p = grabstackstr(concat);
		}
		evalstring(p, EV_TESTED);
	}
	return exitstatus;
}

/*
 * Execute a command or commands contained in a string.
 */

static void evaltree (union node *, int);
static void setinputstring (char *);
static void popfile (void);
static void setstackmark(struct stackmark *mark);
static void popstackmark(struct stackmark *mark);


static void
evalstring(char *s, int flag)
{
	union node *n;
	struct stackmark smark;

	setstackmark(&smark);
	setinputstring(s);
	while ((n = parsecmd(0)) != NEOF) {
		evaltree(n, flag);
		popstackmark(&smark);
	}
	popfile();
	popstackmark(&smark);
}

/*
 * Evaluate a parse tree.  The value is left in the global variable
 * exitstatus.
 */
static struct builtincmd *find_builtin (const char *);
static void defun (char *, union node *);

static void
evaltree(n, flags)
	union node *n;
	int flags;
{
	int checkexit = 0;
	if (n == NULL) {
		TRACE(("evaltree(NULL) called\n"));
		goto out;
	}
	TRACE(("evaltree(0x%lx: %d) called\n", (long)n, n->type));
	switch (n->type) {
	case NSEMI:
		evaltree(n->nbinary.ch1, flags & EV_TESTED);
		if (evalskip)
			goto out;
		evaltree(n->nbinary.ch2, flags);
		break;
	case NAND:
		evaltree(n->nbinary.ch1, EV_TESTED);
		if (evalskip || exitstatus != 0)
			goto out;
		evaltree(n->nbinary.ch2, flags);
		break;
	case NOR:
		evaltree(n->nbinary.ch1, EV_TESTED);
		if (evalskip || exitstatus == 0)
			goto out;
		evaltree(n->nbinary.ch2, flags);
		break;
	case NREDIR:
		expredir(n->nredir.redirect);
		redirect(n->nredir.redirect, REDIR_PUSH);
		evaltree(n->nredir.n, flags);
		popredir();
		break;
	case NSUBSHELL:
		evalsubshell(n, flags);
		break;
	case NBACKGND:
		evalsubshell(n, flags);
		break;
	case NIF: {
		evaltree(n->nif.test, EV_TESTED);
		if (evalskip)
			goto out;
		if (exitstatus == 0)
			evaltree(n->nif.ifpart, flags);
		else if (n->nif.elsepart)
			evaltree(n->nif.elsepart, flags);
		else
			exitstatus = 0;
		break;
	}
	case NWHILE:
	case NUNTIL:
		evalloop(n, flags);
		break;
	case NFOR:
		evalfor(n, flags);
		break;
	case NCASE:
		evalcase(n, flags);
		break;
	case NDEFUN: {
		struct builtincmd *bcmd;
		if (
			(bcmd = find_builtin(n->narg.text)) &&
			IS_BUILTIN_SPECIAL(bcmd)
		) {
			outfmt(out2, "%s is a special built-in\n", n->narg.text);
			exitstatus = 1;
			break;
		}
		defun(n->narg.text, n->narg.next);
		exitstatus = 0;
		break;
	}
	case NNOT:
		evaltree(n->nnot.com, EV_TESTED);
		exitstatus = !exitstatus;
		break;

	case NPIPE:
		evalpipe(n);
		checkexit = 1;
		break;
	case NCMD:
#ifdef notyet
		evalcommand(n, flags, (struct backcmd *)NULL);
#else
		evalcommand(n, flags);
#endif
		checkexit = 1;
		break;
#ifdef DEBUG
	default:
		out1fmt("Node type = %d\n", n->type);
#ifndef USE_GLIBC_STDIO
		flushout(out1);
#endif
		break;
#endif
	}
out:
	if (pendingsigs)
		dotrap();
	if (
		flags & EV_EXIT ||
		(checkexit && eflag && exitstatus && !(flags & EV_TESTED))
	)
		exitshell(exitstatus);
}


static void
evalloop(n, flags)
	union node *n;
	int flags;
{
	int status;

	loopnest++;
	status = 0;
	for (;;) {
		evaltree(n->nbinary.ch1, EV_TESTED);
		if (evalskip) {
skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
				evalskip = 0;
				continue;
			}
			if (evalskip == SKIPBREAK && --skipcount <= 0)
				evalskip = 0;
			break;
		}
		if (n->type == NWHILE) {
			if (exitstatus != 0)
				break;
		} else {
			if (exitstatus == 0)
				break;
		}
		evaltree(n->nbinary.ch2, flags & EV_TESTED);
		status = exitstatus;
		if (evalskip)
			goto skipping;
	}
	loopnest--;
	exitstatus = status;
}

static void expandarg (union node *, struct arglist *, int);
static void fixredir(union node *n, const char *text, int err);

static void
evalfor(n, flags)
    union node *n;
    int flags;
{
	struct arglist arglist;
	union node *argp;
	struct strlist *sp;
	struct stackmark smark;

	setstackmark(&smark);
	arglist.lastp = &arglist.list;
	for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
		oexitstatus = exitstatus;
		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE | EXP_RECORD);
		if (evalskip)
			goto out;
	}
	*arglist.lastp = NULL;

	exitstatus = 0;
	loopnest++;
	for (sp = arglist.list ; sp ; sp = sp->next) {
		setvar(n->nfor.var, sp->text, 0);
		evaltree(n->nfor.body, flags & EV_TESTED);
		if (evalskip) {
			if (evalskip == SKIPCONT && --skipcount <= 0) {
				evalskip = 0;
				continue;
			}
			if (evalskip == SKIPBREAK && --skipcount <= 0)
				evalskip = 0;
			break;
		}
	}
	loopnest--;
out:
	popstackmark(&smark);
}


static void
evalcase(n, flags)
	union node *n;
	int flags;
{
	union node *cp;
	union node *patp;
	struct arglist arglist;
	struct stackmark smark;

	setstackmark(&smark);
	arglist.lastp = &arglist.list;
	oexitstatus = exitstatus;
	expandarg(n->ncase.expr, &arglist, EXP_TILDE);
	for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
		for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
			if (casematch(patp, arglist.list->text)) {
				if (evalskip == 0) {
					evaltree(cp->nclist.body, flags);
				}
				goto out;
			}
		}
	}
out:
	popstackmark(&smark);
}

/*
 * Kick off a subshell to evaluate a tree.
 */

static void
evalsubshell(n, flags)
	union node *n;
	int flags;
{
	struct job *jp;
	int backgnd = (n->type == NBACKGND);

	expredir(n->nredir.redirect);
	jp = makejob(n, 1);
	if (forkshell(jp, n, backgnd) == 0) {
		if (backgnd)
			flags &=~ EV_TESTED;
		redirect(n->nredir.redirect, 0);
		evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
	}
	if (! backgnd) {
		INTOFF;
		exitstatus = waitforjob(jp);
		INTON;
	}
}



/*
 * Compute the names of the files in a redirection list.
 */

static void
expredir(n)
	union node *n;
{
	union node *redir;

	for (redir = n ; redir ; redir = redir->nfile.next) {
		struct arglist fn;
		fn.lastp = &fn.list;
		oexitstatus = exitstatus;
		switch (redir->type) {
		case NFROMTO:
		case NFROM:
		case NTO:
		case NAPPEND:
		case NTOOV:
			expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
			redir->nfile.expfname = fn.list->text;
			break;
		case NFROMFD:
		case NTOFD:
			if (redir->ndup.vname) {
				expandarg(redir->ndup.vname, &fn, EXP_FULL | EXP_TILDE);
				fixredir(redir, fn.list->text, 1);
			}
			break;
		}
	}
}

/*
 * Evaluate a pipeline.  All the processes in the pipeline are children
 * of the process creating the pipeline.  (This differs from some versions
 * of the shell, which make the last process in a pipeline the parent
 * of all the rest.)
 */

static void
evalpipe(n)
	union node *n;
{
	struct job *jp;
	struct nodelist *lp;
	int pipelen;
	int prevfd;
	int pip[2];

	TRACE(("evalpipe(0x%lx) called\n", (long)n));
	pipelen = 0;
	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
		pipelen++;
	INTOFF;
	jp = makejob(n, pipelen);
	prevfd = -1;
	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
		prehash(lp->n);
		pip[1] = -1;
		if (lp->next) {
			if (pipe(pip) < 0) {
				close(prevfd);
				error("Pipe call failed");
			}
		}
		if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
			INTON;
			if (prevfd > 0) {
				close(0);
				dup_as_newfd(prevfd, 0);
				close(prevfd);
				if (pip[0] == 0) {
					pip[0] = -1;
				}
			}
			if (pip[1] >= 0) {
				if (pip[0] >= 0) {
					close(pip[0]);
				}
				if (pip[1] != 1) {
					close(1);
					dup_as_newfd(pip[1], 1);
					close(pip[1]);
				}
			}
			evaltree(lp->n, EV_EXIT);
		}
		if (prevfd >= 0)
			close(prevfd);
		prevfd = pip[0];
		close(pip[1]);
	}
	INTON;
	if (n->npipe.backgnd == 0) {
		INTOFF;
		exitstatus = waitforjob(jp);
		TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
		INTON;
	}
}



/*
 * Execute a command inside back quotes.  If it's a builtin command, we
 * want to save its output in a block obtained from malloc.  Otherwise
 * we fork off a subprocess and get the output of the command via a pipe.
 * Should be called with interrupts off.
 */

static void
evalbackcmd(union node *n, struct backcmd *result)
{
	int pip[2];
	struct job *jp;
	struct stackmark smark;         /* unnecessary */

	setstackmark(&smark);
	result->fd = -1;
	result->buf = NULL;
	result->nleft = 0;
	result->jp = NULL;
	if (n == NULL) {
		exitstatus = 0;
		goto out;
	}
#ifdef notyet
	/*
	 * For now we disable executing builtins in the same
	 * context as the shell, because we are not keeping
	 * enough state to recover from changes that are
	 * supposed only to affect subshells. eg. echo "`cd /`"
	 */
	if (n->type == NCMD) {
		exitstatus = oexitstatus;
		evalcommand(n, EV_BACKCMD, result);
	} else
#endif
	{
		exitstatus = 0;
		if (pipe(pip) < 0)
			error("Pipe call failed");
		jp = makejob(n, 1);
		if (forkshell(jp, n, FORK_NOJOB) == 0) {
			FORCEINTON;
			close(pip[0]);
			if (pip[1] != 1) {
				close(1);
				dup_as_newfd(pip[1], 1);
				close(pip[1]);
			}
			eflag = 0;
			evaltree(n, EV_EXIT);
		}
		close(pip[1]);
		result->fd = pip[0];
		result->jp = jp;
	}
out:
	popstackmark(&smark);
	TRACE(("evalbackcmd done: fd=%d buf=0x%x nleft=%d jp=0x%x\n",
		result->fd, result->buf, result->nleft, result->jp));
}



/*
 * Execute a simple command.
 */

static void find_command (const char *, struct cmdentry *, int, const char *);

static int
isassignment(const char *word) {
	if (!is_name(*word)) {
		return 0;
	}
	do {
		word++;
	} while (is_in_name(*word));
	return *word == '=';
}

static void
#ifdef notyet
evalcommand(cmd, flags, backcmd)
	union node *cmd;
	int flags;
	struct backcmd *backcmd;
#else
evalcommand(cmd, flags)
	union node *cmd;
	int flags;
#endif
{
	struct stackmark smark;
	union node *argp;
	struct arglist arglist;
	struct arglist varlist;
	char **argv;
	int argc;
	char **envp;
	struct strlist *sp;
	int mode;
#ifdef notyet
	int pip[2];
#endif
	struct cmdentry cmdentry;
	struct job *jp;
	char *volatile savecmdname;
	volatile struct shparam saveparam;
	struct localvar *volatile savelocalvars;
	volatile int e;
	char *lastarg;
	const char *path;
	const struct builtincmd *firstbltin;
	struct jmploc *volatile savehandler;
	struct jmploc jmploc;
#if __GNUC__
	/* Avoid longjmp clobbering */
	(void) &argv;
	(void) &argc;
	(void) &lastarg;
	(void) &flags;
#endif

	/* First expand the arguments. */
	TRACE(("evalcommand(0x%lx, %d) called\n", (long)cmd, flags));
	setstackmark(&smark);
	arglist.lastp = &arglist.list;
	varlist.lastp = &varlist.list;
	arglist.list = 0;
	oexitstatus = exitstatus;
	exitstatus = 0;
	path = pathval();
	for (argp = cmd->ncmd.assign; argp; argp = argp->narg.next) {
		expandarg(argp, &varlist, EXP_VARTILDE);
	}
	for (
		argp = cmd->ncmd.args; argp && !arglist.list;
		argp = argp->narg.next
	) {
		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
	}
	if (argp) {
		struct builtincmd *bcmd;
		bool pseudovarflag;
		bcmd = find_builtin(arglist.list->text);
		pseudovarflag = bcmd && IS_BUILTIN_ASSIGN(bcmd);
		for (; argp; argp = argp->narg.next) {
			if (pseudovarflag && isassignment(argp->narg.text)) {
				expandarg(argp, &arglist, EXP_VARTILDE);
				continue;
			}
			expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
		}
	}
	*arglist.lastp = NULL;
	*varlist.lastp = NULL;
	expredir(cmd->ncmd.redirect);
	argc = 0;
	for (sp = arglist.list ; sp ; sp = sp->next)
		argc++;
	argv = stalloc(sizeof (char *) * (argc + 1));

	for (sp = arglist.list ; sp ; sp = sp->next) {
		TRACE(("evalcommand arg: %s\n", sp->text));
		*argv++ = sp->text;
	}
	*argv = NULL;
	lastarg = NULL;
	if (iflag && funcnest == 0 && argc > 0)
		lastarg = argv[-1];
	argv -= argc;

	/* Print the command if xflag is set. */
	if (xflag) {
#ifdef FLUSHERR
		outc('+', &errout);
#else
		outcslow('+', &errout);
#endif
		eprintlist(varlist.list);
		eprintlist(arglist.list);
#ifdef FLUSHERR
		outc('\n', &errout);
		flushout(&errout);
#else
		outcslow('\n', &errout);
#endif
	}

	/* Now locate the command. */
	if (argc == 0) {
		cmdentry.cmdtype = CMDBUILTIN;
		firstbltin = cmdentry.u.cmd = BLTINCMD;
	} else {
		const char *oldpath;
		int findflag = DO_ERR;
		int oldfindflag;

		/*
		 * Modify the command lookup path, if a PATH= assignment
		 * is present
		 */
		for (sp = varlist.list ; sp ; sp = sp->next)
			if (varequal(sp->text, defpathvar)) {
				path = sp->text + 5;
				findflag |= DO_BRUTE;
			}
		oldpath = path;
		oldfindflag = findflag;
		firstbltin = 0;
		for(;;) {
			find_command(argv[0], &cmdentry, findflag, path);
			if (cmdentry.cmdtype == CMDUNKNOWN) {   /* command not found */
				exitstatus = 127;
#ifdef FLUSHERR
				flushout(&errout);
#endif
				goto out;
			}
			/* implement bltin and command here */
			if (cmdentry.cmdtype != CMDBUILTIN) {
				break;
			}
			if (!firstbltin) {
				firstbltin = cmdentry.u.cmd;
			}
			if (cmdentry.u.cmd == BLTINCMD) {
				for(;;) {
					struct builtincmd *bcmd;

					argv++;
					if (--argc == 0)
						goto found;
					if (!(bcmd = find_builtin(*argv))) {
						outfmt(&errout, "%s: not found\n", *argv);
						exitstatus = 127;
#ifdef FLUSHERR
						flushout(&errout);
#endif
						goto out;
					}
					cmdentry.u.cmd = bcmd;
					if (bcmd != BLTINCMD)
						break;
				}
			}
			if (cmdentry.u.cmd == find_builtin("command")) {
				argv++;
				if (--argc == 0) {
					goto found;
				}
				if (*argv[0] == '-') {
					if (!equal(argv[0], "-p")) {
						argv--;
						argc++;
						break;
					}
					argv++;
					if (--argc == 0) {
						goto found;
					}
					path = defpath;
					findflag |= DO_BRUTE;
				} else {
					path = oldpath;
					findflag = oldfindflag;
				}
				findflag |= DO_NOFUN;
				continue;
			}
found:
			break;
		}
	}

	/* Fork off a child process if necessary. */
	if (cmd->ncmd.backgnd
	 || (cmdentry.cmdtype == CMDNORMAL && (flags & EV_EXIT) == 0)
#ifdef notyet
	 || ((flags & EV_BACKCMD) != 0
	    && (cmdentry.cmdtype != CMDBUILTIN
		 || cmdentry.u.bcmd == DOTCMD
		 || cmdentry.u.bcmd == EVALCMD))
#endif
	) {
		jp = makejob(cmd, 1);
		mode = cmd->ncmd.backgnd;
#ifdef notyet
		if (flags & EV_BACKCMD) {
			mode = FORK_NOJOB;
			if (pipe(pip) < 0)
				error("Pipe call failed");
		}
#endif
		if (forkshell(jp, cmd, mode) != 0)
			goto parent;    /* at end of routine */
#ifdef notyet
		if (flags & EV_BACKCMD) {
			FORCEINTON;
			close(pip[0]);
			if (pip[1] != 1) {
				close(1);
				dup_as_newfd(pip[1], 1);
				close(pip[1]);
			}
		}
#endif
		flags |= EV_EXIT;
	}

	/* This is the child process if a fork occurred. */
	/* Execute the command. */
	if (cmdentry.cmdtype == CMDFUNCTION) {
#ifdef DEBUG
		trputs("Shell function:  ");  trargs(argv);
#endif
		exitstatus = oexitstatus;
		redirect(cmd->ncmd.redirect, REDIR_PUSH);
		saveparam = shellparam;
		shellparam.malloc = 0;
		shellparam.nparam = argc - 1;
		shellparam.p = argv + 1;
		INTOFF;
		savelocalvars = localvars;
		localvars = NULL;
		INTON;
		if (setjmp(jmploc.loc)) {
			if (exception == EXSHELLPROC) {
				freeparam((volatile struct shparam *)
				    &saveparam);
			} else {
				saveparam.optind = shellparam.optind;
				saveparam.optoff = shellparam.optoff;
				freeparam(&shellparam);
				shellparam = saveparam;
			}
			poplocalvars();
			localvars = savelocalvars;
			handler = savehandler;
			longjmp(handler->loc, 1);
		}
		savehandler = handler;
		handler = &jmploc;
		for (sp = varlist.list ; sp ; sp = sp->next)
			mklocal(sp->text);
		funcnest++;
		evaltree(cmdentry.u.func, flags & EV_TESTED);
		funcnest--;
		INTOFF;
		poplocalvars();
		localvars = savelocalvars;
		saveparam.optind = shellparam.optind;
		saveparam.optoff = shellparam.optoff;
		freeparam(&shellparam);
		shellparam = saveparam;
		handler = savehandler;
		popredir();
		INTON;
		if (evalskip == SKIPFUNC) {
			evalskip = 0;
			skipcount = 0;
		}
		if (flags & EV_EXIT)
			exitshell(exitstatus);
	} else if (cmdentry.cmdtype == CMDBUILTIN) {
#ifdef DEBUG
		trputs("builtin command:  ");  trargs(argv);
#endif
		mode = (cmdentry.u.cmd == EXECCMD)? 0 : REDIR_PUSH;
#ifdef notyet
		if (flags == EV_BACKCMD) {
#ifdef USE_GLIBC_STDIO
			openmemout();
#else
			memout.nleft = 0;
			memout.nextc = memout.buf;
			memout.bufsize = 64;
#endif
			mode |= REDIR_BACKQ;
		}
#endif
		redirect(cmd->ncmd.redirect, mode);
		savecmdname = commandname;
		if (IS_BUILTIN_SPECIAL(firstbltin)) {
			listsetvar(varlist.list);
		} else {
			cmdenviron = varlist.list;
		}
		e = -1;
		if (setjmp(jmploc.loc)) {
			e = exception;
			exitstatus = (e == EXINT)? SIGINT+128 : 2;
			goto cmddone;
		}
		savehandler = handler;
		handler = &jmploc;
		commandname = argv[0];
		argptr = argv + 1;
		optptr = NULL;                  /* initialize nextopt */
		exitstatus = (*cmdentry.u.cmd->builtinfunc)(argc, argv);
		flushall();
cmddone:
		exitstatus |= outerr(out1);
		out1 = &output;
		out2 = &errout;
		freestdout();
		cmdenviron = NULL;
		if (e != EXSHELLPROC) {
			commandname = savecmdname;
			if (flags & EV_EXIT)
				exitshell(exitstatus);
		}
		handler = savehandler;
		if (e != -1) {
			if ((e != EXERROR && e != EXEXEC)
			   || cmdentry.u.cmd == BLTINCMD
			   || cmdentry.u.cmd == DOTCMD
			   || cmdentry.u.cmd == EVALCMD
			   || cmdentry.u.cmd == EXECCMD)
				exraise(e);
			FORCEINTON;
		}
		if (cmdentry.u.cmd != EXECCMD)
			popredir();
#ifdef notyet
		if (flags == EV_BACKCMD) {
			INTOFF;
#ifdef USE_GLIBC_STDIO
			if (__closememout())
				error("__closememout() failed: %m");
#endif
			backcmd->buf = memout.buf;
#ifdef USE_GLIBC_STDIO
			backcmd->nleft = memout.bufsize;
#else
			backcmd->nleft = memout.nextc - memout.buf;
#endif
			memout.buf = NULL;
			INTON;
		}
#endif
	} else {
#ifdef DEBUG
		trputs("normal command:  ");  trargs(argv);
#endif
		redirect(cmd->ncmd.redirect, 0);
		clearredir();
		for (sp = varlist.list ; sp ; sp = sp->next)
			setvareq(sp->text, VEXPORT|VSTACK);
		envp = environment();
		shellexec(argv, envp, path, cmdentry.u.index);
	}
	goto out;

parent: /* parent process gets here (if we forked) */
	if (mode == 0) {        /* argument to fork */
		INTOFF;
		exitstatus = waitforjob(jp);
		INTON;
#ifdef notyet
	} else if (mode == 2) {
		backcmd->fd = pip[0];
		close(pip[1]);
		backcmd->jp = jp;
#endif
	}

out:
	if (lastarg)
		setvar("_", lastarg, 0);
	popstackmark(&smark);
}



/*
 * Search for a command.  This is called before we fork so that the
 * location of the command will be available in the parent as well as
 * the child.  The check for "goodname" is an overly conservative
 * check that the name will not be subject to expansion.
 */

static void
prehash(n)
	union node *n;
{
	struct cmdentry entry;

	if (n->type == NCMD && n->ncmd.args)
		if (goodname(n->ncmd.args->narg.text))
			find_command(n->ncmd.args->narg.text, &entry, 0,
				     pathval());
}



/*
 * Builtin commands.  Builtin commands whose functions are closely
 * tied to evaluation are implemented here.
 */

/*
 * No command given, or a bltin command with no arguments.  Set the
 * specified variables.
 */

int
bltincmd(argc, argv)
	int argc;
	char **argv;
{
	/*
	 * Preserve exitstatus of a previous possible redirection
	 * as POSIX mandates
	 */
	return exitstatus;
}


/*
 * Handle break and continue commands.  Break, continue, and return are
 * all handled by setting the evalskip flag.  The evaluation routines
 * above all check this flag, and if it is set they start skipping
 * commands rather than executing them.  The variable skipcount is
 * the number of loops to break/continue, or the number of function
 * levels to return.  (The latter is always 1.)  It should probably
 * be an error to break out of more loops than exist, but it isn't
 * in the standard shell so we don't make it one here.
 */

static int
breakcmd(argc, argv)
	int argc;
	char **argv;
{
	int n = argc > 1 ? number(argv[1]) : 1;

	if (n > loopnest)
		n = loopnest;
	if (n > 0) {
		evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
		skipcount = n;
	}
	return 0;
}


/*
 * The return command.
 */

static int
returncmd(argc, argv)
	int argc;
	char **argv;
{
	int ret = argc > 1 ? number(argv[1]) : oexitstatus;

	if (funcnest) {
		evalskip = SKIPFUNC;
		skipcount = 1;
		return ret;
	}
	else {
		/* Do what ksh does; skip the rest of the file */
		evalskip = SKIPFILE;
		skipcount = 1;
		return ret;
	}
}


#ifndef BB_TRUE_FALSE
#ifdef ASH_BBAPPS_AS_BUILTINS
static int
false_main(argc, argv)
	int argc;
	char **argv;
{
	return 1;
}


static int
true_main(argc, argv)
	int argc;
	char **argv;
{
	return 0;
}
#endif
#endif

/*
 * Controls whether the shell is interactive or not.
 */

static void setsignal(int signo);
static void chkmail(int silent);


static void
setinteractive(int on)
{
	static int is_interactive;

	if (on == is_interactive)
		return;
	setsignal(SIGINT);
	setsignal(SIGQUIT);
	setsignal(SIGTERM);
	chkmail(1);
	is_interactive = on;
}

static void
optschanged(void)
{
	setinteractive(iflag);
	setjobctl(mflag);
}


static int
execcmd(argc, argv)
	int argc;
	char **argv;
{
	if (argc > 1) {
		struct strlist *sp;

		iflag = 0;              /* exit on error */
		mflag = 0;
		optschanged();
		for (sp = cmdenviron; sp ; sp = sp->next)
			setvareq(sp->text, VEXPORT|VSTACK);
		shellexec(argv + 1, environment(), pathval(), 0);
	}
	return 0;
}

static void
eprintlist(struct strlist *sp)
{
	for (; sp; sp = sp->next) {
		outfmt(&errout, " %s",sp->text);
	}
}
/*
 * When commands are first encountered, they are entered in a hash table.
 * This ensures that a full path search will not have to be done for them
 * on each invocation.
 *
 * We should investigate converting to a linear search, even though that
 * would make the command name "hash" a misnomer.
 */
#define CMDTABLESIZE 31         /* should be prime */
#define ARB 1                   /* actual size determined at run time */



struct tblentry {
	struct tblentry *next;  /* next entry in hash chain */
	union param param;      /* definition of builtin function */
	short cmdtype;          /* index identifying command */
	char rehash;            /* if set, cd done since entry created */
	char cmdname[ARB];      /* name of command */
};


static struct tblentry *cmdtable[CMDTABLESIZE];
static int builtinloc = -1;             /* index in path of %builtin, or -1 */
static int exerrno = 0;                 /* Last exec error */


static void tryexec (char *, char **, char **);
static void printentry (struct tblentry *, int);
static void clearcmdentry (int);
static struct tblentry *cmdlookup (const char *, int);
static void delete_cmd_entry (void);
#ifdef ASH_TYPE
static int describe_command (char *, int);
#endif
static int path_change (const char *, int *);


/*
 * Exec a program.  Never returns.  If you change this routine, you may
 * have to change the find_command routine as well.
 */

static const char *pathopt;     /* set by padvance */

static void
shellexec(argv, envp, path, idx)
	char **argv, **envp;
	const char *path;
	int idx;
{
	char *cmdname;
	int e;

	if (strchr(argv[0], '/') != NULL) {
		tryexec(argv[0], argv, envp);
		e = errno;
	} else {
		e = ENOENT;
		while ((cmdname = padvance(&path, argv[0])) != NULL) {
			if (--idx < 0 && pathopt == NULL) {
				tryexec(cmdname, argv, envp);
				if (errno != ENOENT && errno != ENOTDIR)
					e = errno;
			}
			stunalloc(cmdname);
		}
	}

	/* Map to POSIX errors */
	switch (e) {
	case EACCES:
		exerrno = 126;
		break;
	case ENOENT:
		exerrno = 127;
		break;
	default:
		exerrno = 2;
		break;
	}
	exerror(EXEXEC, "%s: %s", argv[0], errmsg(e, E_EXEC));
	/* NOTREACHED */
}

/*
 * Clear traps on a fork.
 */
static void
clear_traps(void) {
	char **tp;

	for (tp = trap ; tp < &trap[NSIG] ; tp++) {
		if (*tp && **tp) {      /* trap not NULL or SIG_IGN */
			INTOFF;
			ckfree(*tp);
			*tp = NULL;
			if (tp != &trap[0])
				setsignal(tp - trap);
			INTON;
		}
	}
}


static void
initshellproc(void) {

#ifdef ASH_ALIAS
      /* from alias.c: */
      {
	      rmaliases();
      }
#endif
      /* from eval.c: */
      {
	      exitstatus = 0;
      }

      /* from exec.c: */
      {
	      deletefuncs();
      }

      /* from jobs.c: */
      {
	      backgndpid = -1;
#ifdef JOBS
	      jobctl = 0;
#endif
      }

      /* from options.c: */
      {
	      int i;

	      for (i = 0; i < NOPTS; i++)
		      optent_val(i) = 0;
	      optschanged();

      }

      /* from redir.c: */
      {
	      clearredir();
      }

      /* from trap.c: */
      {
	      char *sm;

	      clear_traps();
	      for (sm = sigmode ; sm < sigmode + NSIG - 1; sm++) {
		      if (*sm == S_IGN)
			      *sm = S_HARD_IGN;
	      }
      }

      /* from var.c: */
      {
	      shprocvar();
      }
}

static int preadbuffer(void);
static void pushfile (void);
static int preadfd (void);

/*
 * Read a character from the script, returning PEOF on end of file.
 * Nul characters in the input are silently discarded.
 */

#ifdef ASH_BBAPPS_AS_BUILTINS
#define pgetc_macro()   (--parsenleft >= 0? *parsenextc++ : preadbuffer())
static int
pgetc(void)
{
	return pgetc_macro();
}
#else
static int
pgetc_macro(void)
{
	return --parsenleft >= 0? *parsenextc++ : preadbuffer();
}

static inline int
pgetc(void)
{
	return pgetc_macro();
}
#endif


/*
 * Undo the last call to pgetc.  Only one character may be pushed back.
 * PEOF may be pushed back.
 */

static void
pungetc() {
	parsenleft++;
	parsenextc--;
}


static void
popfile(void) {
	struct parsefile *pf = parsefile;

	INTOFF;
	if (pf->fd >= 0)
		close(pf->fd);
	if (pf->buf)
		ckfree(pf->buf);
	while (pf->strpush)
		popstring();
	parsefile = pf->prev;
	ckfree(pf);
	parsenleft = parsefile->nleft;
	parselleft = parsefile->lleft;
	parsenextc = parsefile->nextc;
	plinno = parsefile->linno;
	INTON;
}


/*
 * Return to top level.
 */

static void
popallfiles(void) {
	while (parsefile != &basepf)
		popfile();
}

/*
 * Close the file(s) that the shell is reading commands from.  Called
 * after a fork is done.
 */

static void
closescript() {
	popallfiles();
	if (parsefile->fd > 0) {
		close(parsefile->fd);
		parsefile->fd = 0;
	}
}


/*
 * Like setinputfile, but takes an open file descriptor.  Call this with
 * interrupts off.
 */

static void
setinputfd(fd, push)
	int fd, push;
{
	(void) fcntl(fd, F_SETFD, FD_CLOEXEC);
	if (push) {
		pushfile();
		parsefile->buf = 0;
	} else {
		closescript();
		while (parsefile->strpush)
			popstring();
	}
	parsefile->fd = fd;
	if (parsefile->buf == NULL)
		parsefile->buf = ckmalloc(BUFSIZ);
	parselleft = parsenleft = 0;
	plinno = 1;
}


/*
 * Set the input to take input from a file.  If push is set, push the
 * old input onto the stack first.
 */

static void
setinputfile(const char *fname, int push)
{
	int fd;
	int myfileno2;

	INTOFF;
	if ((fd = open(fname, O_RDONLY)) < 0)
		error("Can't open %s", fname);
	if (fd < 10) {
		myfileno2 = dup_as_newfd(fd, 10);
		close(fd);
		if (myfileno2 < 0)
			error("Out of file descriptors");
		fd = myfileno2;
	}
	setinputfd(fd, push);
	INTON;
}


static void
tryexec(cmd, argv, envp)
	char *cmd;
	char **argv;
	char **envp;
	{
	int e;

	execve(cmd, argv, envp);
	e = errno;
	if (e == ENOEXEC) {
		INTOFF;
		initshellproc();
		setinputfile(cmd, 0);
		commandname = arg0 = savestr(argv[0]);
		setparam(argv + 1);
		exraise(EXSHELLPROC);
	}
	errno = e;
}

static char *commandtext (const union node *);

/*
 * Do a path search.  The variable path (passed by reference) should be
 * set to the start of the path before the first call; padvance will update
 * this value as it proceeds.  Successive calls to padvance will return
 * the possible path expansions in sequence.  If an option (indicated by
 * a percent sign) appears in the path entry then the global variable
 * pathopt will be set to point to it; otherwise pathopt will be set to
 * NULL.
 */

static const char *pathopt;

static void growstackblock(void);


static char *
padvance(const char **path, const char *name)
{
	const char *p;
	char *q;
	const char *start;
	int len;

	if (*path == NULL)
		return NULL;
	start = *path;
	for (p = start ; *p && *p != ':' && *p != '%' ; p++);
	len = p - start + strlen(name) + 2;     /* "2" is for '/' and '\0' */
	while (stackblocksize() < len)
		growstackblock();
	q = stackblock();
	if (p != start) {
		memcpy(q, start, p - start);
		q += p - start;
		*q++ = '/';
	}
	strcpy(q, name);
	pathopt = NULL;
	if (*p == '%') {
		pathopt = ++p;
		while (*p && *p != ':')  p++;
	}
	if (*p == ':')
		*path = p + 1;
	else
		*path = NULL;
	return stalloc(len);
}



/*** Command hashing code ***/


static int
hashcmd(argc, argv)
	int argc;
	char **argv;
{
	struct tblentry **pp;
	struct tblentry *cmdp;
	int c;
	int verbose;
	struct cmdentry entry;
	char *name;

	verbose = 0;
	while ((c = nextopt("rv")) != '\0') {
		if (c == 'r') {
			clearcmdentry(0);
			return 0;
		} else if (c == 'v') {
			verbose++;
		}
	}
	if (*argptr == NULL) {
		for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
			for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
				if (cmdp->cmdtype != CMDBUILTIN) {
					printentry(cmdp, verbose);
				}
			}
		}
		return 0;
	}
	c = 0;
	while ((name = *argptr) != NULL) {
		if ((cmdp = cmdlookup(name, 0)) != NULL
		 && (cmdp->cmdtype == CMDNORMAL
		     || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)))
			delete_cmd_entry();
		find_command(name, &entry, DO_ERR, pathval());
		if (entry.cmdtype == CMDUNKNOWN) c = 1;
		else if (verbose) {
			cmdp = cmdlookup(name, 0);
			if (cmdp) printentry(cmdp, verbose);
			flushall();
		}
		argptr++;
	}
	return c;
}


static void
printentry(cmdp, verbose)
	struct tblentry *cmdp;
	int verbose;
	{
	int idx;
	const char *path;
	char *name;

	if (cmdp->cmdtype == CMDNORMAL) {
		idx = cmdp->param.index;
		path = pathval();
		do {
			name = padvance(&path, cmdp->cmdname);
			stunalloc(name);
		} while (--idx >= 0);
		out1str(name);
	} else if (cmdp->cmdtype == CMDBUILTIN) {
		out1fmt("builtin %s", cmdp->cmdname);
	} else if (cmdp->cmdtype == CMDFUNCTION) {
		out1fmt("function %s", cmdp->cmdname);
		if (verbose) {
			INTOFF;
			name = commandtext(cmdp->param.func);
			out1fmt(" %s", name);
			ckfree(name);
			INTON;
		}
#ifdef DEBUG
	} else {
		error("internal error: cmdtype %d", cmdp->cmdtype);
#endif
	}
	out1fmt(snlfmt, cmdp->rehash ? "*" : nullstr);
}



/*
 * Resolve a command name.  If you change this routine, you may have to
 * change the shellexec routine as well.
 */

static int prefix (const char *, const char *);

static void
find_command(const char *name, struct cmdentry *entry, int act, const char *path)
{
	struct tblentry *cmdp;
	int idx;
	int prev;
	char *fullname;
	struct stat statb;
	int e;
	int bltin;
	int firstchange;
	int updatetbl;
	bool regular;
	struct builtincmd *bcmd;

	/* If name contains a slash, don't use the hash table */
	if (strchr(name, '/') != NULL) {
		if (act & DO_ABS) {
			while (stat(name, &statb) < 0) {
				if (errno != ENOENT && errno != ENOTDIR)
					e = errno;
				entry->cmdtype = CMDUNKNOWN;
				entry->u.index = -1;
				return;
			}
			entry->cmdtype = CMDNORMAL;
			entry->u.index = -1;
			return;
		}
		entry->cmdtype = CMDNORMAL;
		entry->u.index = 0;
		return;
	}

	updatetbl = 1;
	if (act & DO_BRUTE) {
		firstchange = path_change(path, &bltin);
	} else {
		bltin = builtinloc;
		firstchange = 9999;
	}

	/* If name is in the table, and not invalidated by cd, we're done */
	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0) {
		if (cmdp->cmdtype == CMDFUNCTION) {
			if (act & DO_NOFUN) {
				updatetbl = 0;
			} else {
				goto success;
			}
		} else if (act & DO_BRUTE) {
			if ((cmdp->cmdtype == CMDNORMAL &&
			     cmdp->param.index >= firstchange) ||
			    (cmdp->cmdtype == CMDBUILTIN &&
			     ((builtinloc < 0 && bltin >= 0) ?
			      bltin : builtinloc) >= firstchange)) {
				/* need to recompute the entry */
			} else {
				goto success;
			}
		} else {
			goto success;
		}
	}

	bcmd = find_builtin(name);
	regular = bcmd && IS_BUILTIN_REGULAR(bcmd);

	if (regular) {
		if (cmdp && (cmdp->cmdtype == CMDBUILTIN)) {
			goto success;
		}
	} else if (act & DO_BRUTE) {
		if (firstchange == 0) {
			updatetbl = 0;
		}
	}

	/* If %builtin not in path, check for builtin next */
	if (regular || (bltin < 0 && bcmd)) {
builtin:
		if (!updatetbl) {
			entry->cmdtype = CMDBUILTIN;
			entry->u.cmd = bcmd;
			return;
		}
		INTOFF;
		cmdp = cmdlookup(name, 1);
		cmdp->cmdtype = CMDBUILTIN;
		cmdp->param.cmd = bcmd;
		INTON;
		goto success;
	}

	/* We have to search path. */
	prev = -1;              /* where to start */
	if (cmdp && cmdp->rehash) {     /* doing a rehash */
		if (cmdp->cmdtype == CMDBUILTIN)
			prev = builtinloc;
		else
			prev = cmdp->param.index;
	}

	e = ENOENT;
	idx = -1;
loop:
	while ((fullname = padvance(&path, name)) != NULL) {
		stunalloc(fullname);
		idx++;
		if (idx >= firstchange) {
			updatetbl = 0;
		}
		if (pathopt) {
			if (prefix("builtin", pathopt)) {
				if ((bcmd = find_builtin(name))) {
					goto builtin;
				}
				continue;
			} else if (!(act & DO_NOFUN) &&
				   prefix("func", pathopt)) {
				/* handled below */
			} else {
				continue;       /* ignore unimplemented options */
			}
		}
		/* if rehash, don't redo absolute path names */
		if (fullname[0] == '/' && idx <= prev &&
		    idx < firstchange) {
			if (idx < prev)
				continue;
			TRACE(("searchexec \"%s\": no change\n", name));
			goto success;
		}
		while (stat(fullname, &statb) < 0) {
			if (errno != ENOENT && errno != ENOTDIR)
				e = errno;
			goto loop;
		}
		e = EACCES;     /* if we fail, this will be the error */
		if (!S_ISREG(statb.st_mode))
			continue;
		if (pathopt) {          /* this is a %func directory */
			stalloc(strlen(fullname) + 1);
			readcmdfile(fullname);
			if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
				error("%s not defined in %s", name, fullname);
			stunalloc(fullname);
			goto success;
		}
		TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
		/* If we aren't called with DO_BRUTE and cmdp is set, it must
		   be a function and we're being called with DO_NOFUN */
		if (!updatetbl) {
			entry->cmdtype = CMDNORMAL;
			entry->u.index = idx;
			return;
		}
		INTOFF;
		cmdp = cmdlookup(name, 1);
		cmdp->cmdtype = CMDNORMAL;
		cmdp->param.index = idx;
		INTON;
		goto success;
	}

	/* We failed.  If there was an entry for this command, delete it */
	if (cmdp && updatetbl)
		delete_cmd_entry();
	if (act & DO_ERR)
		outfmt(out2, "%s: %s\n", name, errmsg(e, E_EXEC));
	entry->cmdtype = CMDUNKNOWN;
	return;

success:
	cmdp->rehash = 0;
	entry->cmdtype = cmdp->cmdtype;
	entry->u = cmdp->param;
}



/*
 * Search the table of builtin commands.
 */

static int
bstrcmp(const void *name, const void *b)
{
	return strcmp((const char *)name, (*(const char *const *) b)+1);
}

static struct builtincmd *
find_builtin(const char *name)
{
	struct builtincmd *bp;

	bp = bsearch(name, builtincmds, NUMBUILTINS, sizeof(struct builtincmd),
		bstrcmp
	);
	return bp;
}


/*
 * Called when a cd is done.  Marks all commands so the next time they
 * are executed they will be rehashed.
 */

static void
hashcd(void) {
	struct tblentry **pp;
	struct tblentry *cmdp;

	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
		for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
			if (cmdp->cmdtype == CMDNORMAL
			 || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))
				cmdp->rehash = 1;
		}
	}
}



/*
 * Called before PATH is changed.  The argument is the new value of PATH;
 * pathval() still returns the old value at this point.  Called with
 * interrupts off.
 */

static void
changepath(const char *newval)
{
	int firstchange;
	int bltin;

	firstchange = path_change(newval, &bltin);
	if (builtinloc < 0 && bltin >= 0)
		builtinloc = bltin;             /* zap builtins */
	clearcmdentry(firstchange);
	builtinloc = bltin;
}


/*
 * Clear out command entries.  The argument specifies the first entry in
 * PATH which has changed.
 */

static void
clearcmdentry(firstchange)
	int firstchange;
{
	struct tblentry **tblp;
	struct tblentry **pp;
	struct tblentry *cmdp;

	INTOFF;
	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
		pp = tblp;
		while ((cmdp = *pp) != NULL) {
			if ((cmdp->cmdtype == CMDNORMAL &&
			     cmdp->param.index >= firstchange)
			 || (cmdp->cmdtype == CMDBUILTIN &&
			     builtinloc >= firstchange)) {
				*pp = cmdp->next;
				ckfree(cmdp);
			} else {
				pp = &cmdp->next;
			}
		}
	}
	INTON;
}

/*
 * Free a parse tree.
 */

static void
freefunc(union node *n)
{
	if (n)
		ckfree(n);
}


/*
 * Delete all functions.
 */

static void
deletefuncs(void) {
	struct tblentry **tblp;
	struct tblentry **pp;
	struct tblentry *cmdp;

	INTOFF;
	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
		pp = tblp;
		while ((cmdp = *pp) != NULL) {
			if (cmdp->cmdtype == CMDFUNCTION) {
				*pp = cmdp->next;
				freefunc(cmdp->param.func);
				ckfree(cmdp);
			} else {
				pp = &cmdp->next;
			}
		}
	}
	INTON;
}



/*
 * Locate a command in the command hash table.  If "add" is nonzero,
 * add the command to the table if it is not already present.  The
 * variable "lastcmdentry" is set to point to the address of the link
 * pointing to the entry, so that delete_cmd_entry can delete the
 * entry.
 */

static struct tblentry **lastcmdentry;

static struct tblentry *
cmdlookup(const char *name, int add)
{
	int hashval;
	const char *p;
	struct tblentry *cmdp;
	struct tblentry **pp;

	p = name;
	hashval = *p << 4;
	while (*p)
		hashval += *p++;
	hashval &= 0x7FFF;
	pp = &cmdtable[hashval % CMDTABLESIZE];
	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
		if (equal(cmdp->cmdname, name))
			break;
		pp = &cmdp->next;
	}
	if (add && cmdp == NULL) {
		INTOFF;
		cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB
					+ strlen(name) + 1);
		cmdp->next = NULL;
		cmdp->cmdtype = CMDUNKNOWN;
		cmdp->rehash = 0;
		strcpy(cmdp->cmdname, name);
		INTON;
	}
	lastcmdentry = pp;
	return cmdp;
}

/*
 * Delete the command entry returned on the last lookup.
 */

static void
delete_cmd_entry() {
	struct tblentry *cmdp;

	INTOFF;
	cmdp = *lastcmdentry;
	*lastcmdentry = cmdp->next;
	ckfree(cmdp);
	INTON;
}



/*
 * Add a new command entry, replacing any existing command entry for
 * the same name.
 */

static void
addcmdentry(char *name, struct cmdentry *entry)
{
	struct tblentry *cmdp;

	INTOFF;
	cmdp = cmdlookup(name, 1);
	if (cmdp->cmdtype == CMDFUNCTION) {
		freefunc(cmdp->param.func);
	}
	cmdp->cmdtype = entry->cmdtype;
	cmdp->param = entry->u;
	INTON;
}


/*
 * Define a shell function.
 */

static union node *copyfunc(union node *);

static void
defun(char *name, union node *func)
{
	struct cmdentry entry;

	entry.cmdtype = CMDFUNCTION;
	entry.u.func = copyfunc(func);
	addcmdentry(name, &entry);
}


/*
 * Delete a function if it exists.
 */

static void
unsetfunc(char *name)
{
	struct tblentry *cmdp;

	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
		freefunc(cmdp->param.func);
		delete_cmd_entry();
	}
}

/*
 * Wrapper around strcmp for qsort/bsearch/...
 */
static int
pstrcmp(const void *a, const void *b)
{
	return strcmp((const char *) a, *(const char *const *) b);
}

/*
 * Find a keyword is in a sorted array.
 */

static const char *const *
findkwd(const char *s)
{
	return  bsearch(s, parsekwd, sizeof(parsekwd) / sizeof(const char *),
			sizeof(const char *), pstrcmp);
}

#ifdef ASH_TYPE
/*
 * Locate and print what a word is...
 */

static int
typecmd(argc, argv)
	int argc;
	char **argv;
{
	int i;
	int err = 0;

	for (i = 1; i < argc; i++) {
		err |= describe_command(argv[i], 1);
	}
	return err;
}

static int
describe_command(char *command, int verbose)
{
	struct cmdentry entry;
	struct tblentry *cmdp;
#ifdef ASH_ALIAS
	const struct alias *ap;
#endif
	const char *path = pathval();

	if (verbose) {
		out1str(command);
	}

	/* First look at the keywords */
	if (findkwd(command)) {
		out1str(verbose ? " is a shell keyword" : command);
		goto out;
	}

#ifdef ASH_ALIAS
	/* Then look at the aliases */
	if ((ap = lookupalias(command, 0)) != NULL) {
		if (verbose) {
			out1fmt(" is an alias for %s", ap->val);
		} else {
			printalias(ap);
		}
		goto out;
	}
#endif
	/* Then check if it is a tracked alias */
	if ((cmdp = cmdlookup(command, 0)) != NULL) {
		entry.cmdtype = cmdp->cmdtype;
		entry.u = cmdp->param;
	} else {
		/* Finally use brute force */
		find_command(command, &entry, DO_ABS, path);
	}

	switch (entry.cmdtype) {
	case CMDNORMAL: {
		int j = entry.u.index;
		char *p;
		if (j == -1) {
			p = command;
		} else {
			do {
				p = padvance(&path, command);
				stunalloc(p);
			} while (--j >= 0);
		}
		if (verbose) {
			out1fmt(
				" is%s %s",
				cmdp ? " a tracked alias for" : nullstr, p
			);
		} else {
			out1str(p);
		}
		break;
	}

	case CMDFUNCTION:
		if (verbose) {
			out1str(" is a shell function");
		} else {
			out1str(command);
		}
		break;

	case CMDBUILTIN:
		if (verbose) {
			out1fmt(
				" is a %sshell builtin",
				IS_BUILTIN_SPECIAL(entry.u.cmd) ?
					"special " : nullstr
			);
		} else {
			out1str(command);
		}
		break;

	default:
		if (verbose) {
			out1str(": not found\n");
		}
		return 127;
	}

out:
	out1c('\n');
	return 0;
}
#endif

#ifdef ASH_CMDCMD
static int
commandcmd(argc, argv)
	int argc;
	char **argv;
{
	int c;
	int default_path = 0;
	int verify_only = 0;
	int verbose_verify_only = 0;

	while ((c = nextopt("pvV")) != '\0')
		switch (c) {
		case 'p':
			default_path = 1;
			break;
		case 'v':
			verify_only = 1;
			break;
		case 'V':
			verbose_verify_only = 1;
			break;
		default:
			outfmt(out2,
"command: nextopt returned character code 0%o\n", c);
			return EX_SOFTWARE;
		}

	if (default_path + verify_only + verbose_verify_only > 1 ||
	    !*argptr) {
			outfmt(out2,
"command [-p] command [arg ...]\n");
			outfmt(out2,
"command {-v|-V} command\n");
			return EX_USAGE;
	}

#ifdef ASH_TYPE
	if (verify_only || verbose_verify_only) {
		return describe_command(*argptr, verbose_verify_only);
	}
#endif

	return 0;
}
#endif

static int
path_change(newval, bltin)
	const char *newval;
	int *bltin;
{
	const char *old, *new;
	int idx;
	int firstchange;

	old = pathval();
	new = newval;
	firstchange = 9999;     /* assume no change */
	idx = 0;
	*bltin = -1;
	for (;;) {
		if (*old != *new) {
			firstchange = idx;
			if ((*old == '\0' && *new == ':')
			 || (*old == ':' && *new == '\0'))
				firstchange++;
			old = new;      /* ignore subsequent differences */
		}
		if (*new == '\0')
			break;
		if (*new == '%' && *bltin < 0 && prefix("builtin", new + 1))
			*bltin = idx;
		if (*new == ':') {
			idx++;
		}
		new++, old++;
	}
	if (builtinloc >= 0 && *bltin < 0)
		firstchange = 0;
	return firstchange;
}
/*
 * Routines to expand arguments to commands.  We have to deal with
 * backquotes, shell variables, and file metacharacters.
 */
/*
 * _rmescape() flags
 */
#define RMESCAPE_ALLOC  0x1     /* Allocate a new string */
#define RMESCAPE_GLOB   0x2     /* Add backslashes for glob */

/*
 * Structure specifying which parts of the string should be searched
 * for IFS characters.
 */

struct ifsregion {
	struct ifsregion *next; /* next region in list */
	int begoff;             /* offset of start of region */
	int endoff;             /* offset of end of region */
	int nulonly;            /* search for nul bytes only */
};


static char *expdest;                   /* output of current string */
static struct nodelist *argbackq;      /* list of back quote expressions */
static struct ifsregion ifsfirst;      /* first struct in list of ifs regions */
static struct ifsregion *ifslastp;     /* last struct in list */
static struct arglist exparg;          /* holds expanded arg list */

static void argstr (char *, int);
static char *exptilde (char *, int);
static void expbackq (union node *, int, int);
static int subevalvar (char *, char *, int, int, int, int, int);
static char *evalvar (char *, int);
static int varisset (char *, int);
static void strtodest (const char *, const char *, int);
static void varvalue (char *, int, int);
static void recordregion (int, int, int);
static void removerecordregions (int);
static void ifsbreakup (char *, struct arglist *);
static void ifsfree (void);
static void expandmeta (struct strlist *, int);
#if defined(__GLIBC__) && !defined(FNMATCH_BROKEN)
#define preglob(p) _rmescapes((p), RMESCAPE_ALLOC | RMESCAPE_GLOB)
#if !defined(GLOB_BROKEN)
static void addglob (const glob_t *);
#endif
#endif
#if !(defined(__GLIBC__) && !defined(FNMATCH_BROKEN) && !defined(GLOB_BROKEN))
static void expmeta (char *, char *);
#endif
#if !(defined(__GLIBC__) && !defined(FNMATCH_BROKEN) && !defined(GLOB_BROKEN))
static struct strlist *expsort (struct strlist *);
static struct strlist *msort (struct strlist *, int);
#endif
#if defined(__GLIBC__) && !defined(FNMATCH_BROKEN)
static int patmatch (char *, char *, int);
static int patmatch2 (char *, char *, int);
#else
static int pmatch (char *, char *, int);
#define patmatch2 patmatch
#endif
static char *cvtnum (int, char *);

/*
 * Expand shell variables and backquotes inside a here document.
 */

/* arg: the document, fd: where to write the expanded version */
static void
expandhere(union node *arg, int fd)
{
	herefd = fd;
	expandarg(arg, (struct arglist *)NULL, 0);
	xwrite(fd, stackblock(), expdest - stackblock());
}


/*
 * Perform variable substitution and command substitution on an argument,
 * placing the resulting list of arguments in arglist.  If EXP_FULL is true,
 * perform splitting and file name expansion.  When arglist is NULL, perform
 * here document expansion.
 */

static void
expandarg(arg, arglist, flag)
	union node *arg;
	struct arglist *arglist;
	int flag;
{
	struct strlist *sp;
	char *p;

	argbackq = arg->narg.backquote;
	STARTSTACKSTR(expdest);
	ifsfirst.next = NULL;
	ifslastp = NULL;
	argstr(arg->narg.text, flag);
	if (arglist == NULL) {
		return;                 /* here document expanded */
	}
	STPUTC('\0', expdest);
	p = grabstackstr(expdest);
	exparg.lastp = &exparg.list;
	/*
	 * TODO - EXP_REDIR
	 */
	if (flag & EXP_FULL) {
		ifsbreakup(p, &exparg);
		*exparg.lastp = NULL;
		exparg.lastp = &exparg.list;
		expandmeta(exparg.list, flag);
	} else {
		if (flag & EXP_REDIR) /*XXX - for now, just remove escapes */
			rmescapes(p);
		sp = (struct strlist *)stalloc(sizeof (struct strlist));
		sp->text = p;
		*exparg.lastp = sp;
		exparg.lastp = &sp->next;
	}
	ifsfree();
	*exparg.lastp = NULL;
	if (exparg.list) {
		*arglist->lastp = exparg.list;
		arglist->lastp = exparg.lastp;
	}
}



/*
 * Perform variable and command substitution.  If EXP_FULL is set, output CTLESC
 * characters to allow for further processing.  Otherwise treat
 * $@ like $* since no splitting will be performed.
 */

static void
argstr(p, flag)
	char *p;
	int flag;
{
	char c;
	int quotes = flag & (EXP_FULL | EXP_CASE);      /* do CTLESC */
	int firsteq = 1;

	if (*p == '~' && (flag & (EXP_TILDE | EXP_VARTILDE)))
		p = exptilde(p, flag);
	for (;;) {
		switch (c = *p++) {
		case '\0':
		case CTLENDVAR: /* ??? */
			goto breakloop;
		case CTLQUOTEMARK:
			/* "$@" syntax adherence hack */
			if (p[0] == CTLVAR && p[2] == '@' && p[3] == '=')
				break;
			if ((flag & EXP_FULL) != 0)
				STPUTC(c, expdest);
			break;
		case CTLESC:
			if (quotes)
				STPUTC(c, expdest);
			c = *p++;
			STPUTC(c, expdest);
			break;
		case CTLVAR:
			p = evalvar(p, flag);
			break;
		case CTLBACKQ:
		case CTLBACKQ|CTLQUOTE:
			expbackq(argbackq->n, c & CTLQUOTE, flag);
			argbackq = argbackq->next;
			break;
#ifdef ASH_MATH_SUPPORT
		case CTLENDARI:
			expari(flag);
			break;
#endif
		case ':':
		case '=':
			/*
			 * sort of a hack - expand tildes in variable
			 * assignments (after the first '=' and after ':'s).
			 */
			STPUTC(c, expdest);
			if (flag & EXP_VARTILDE && *p == '~') {
				if (c == '=') {
					if (firsteq)
						firsteq = 0;
					else
						break;
				}
				p = exptilde(p, flag);
			}
			break;
		default:
			STPUTC(c, expdest);
		}
	}
breakloop:;
	return;
}

static char *
exptilde(p, flag)
	char *p;
	int flag;
{
	char c, *startp = p;
	struct passwd *pw;
	const char *home;
	int quotes = flag & (EXP_FULL | EXP_CASE);

	while ((c = *p) != '\0') {
		switch(c) {
		case CTLESC:
			return (startp);
		case CTLQUOTEMARK:
			return (startp);
		case ':':
			if (flag & EXP_VARTILDE)
				goto done;
			break;
		case '/':
			goto done;
		}
		p++;
	}
done:
	*p = '\0';
	if (*(startp+1) == '\0') {
		if ((home = lookupvar("HOME")) == NULL)
			goto lose;
	} else {
		if ((pw = getpwnam(startp+1)) == NULL)
			goto lose;
		home = pw->pw_dir;
	}
	if (*home == '\0')
		goto lose;
	*p = c;
	strtodest(home, SQSYNTAX, quotes);
	return (p);
lose:
	*p = c;
	return (startp);
}


static void
removerecordregions(int endoff)
{
	if (ifslastp == NULL)
		return;

	if (ifsfirst.endoff > endoff) {
		while (ifsfirst.next != NULL) {
			struct ifsregion *ifsp;
			INTOFF;
			ifsp = ifsfirst.next->next;
			ckfree(ifsfirst.next);
			ifsfirst.next = ifsp;
			INTON;
		}
		if (ifsfirst.begoff > endoff)
			ifslastp = NULL;
		else {
			ifslastp = &ifsfirst;
			ifsfirst.endoff = endoff;
		}
		return;
	}

	ifslastp = &ifsfirst;
	while (ifslastp->next && ifslastp->next->begoff < endoff)
		ifslastp=ifslastp->next;
	while (ifslastp->next != NULL) {
		struct ifsregion *ifsp;
		INTOFF;
		ifsp = ifslastp->next->next;
		ckfree(ifslastp->next);
		ifslastp->next = ifsp;
		INTON;
	}
	if (ifslastp->endoff > endoff)
		ifslastp->endoff = endoff;
}


#ifdef ASH_MATH_SUPPORT
/*
 * Expand arithmetic expression.  Backup to start of expression,
 * evaluate, place result in (backed up) result, adjust string position.
 */
static void
expari(int flag)
{
	char *p, *start;
	int result;
	int begoff;
	int quotes = flag & (EXP_FULL | EXP_CASE);
	int quoted;

	/*      ifsfree(); */

	/*
	 * This routine is slightly over-complicated for
	 * efficiency.  First we make sure there is
	 * enough space for the result, which may be bigger
	 * than the expression if we add exponentation.  Next we
	 * scan backwards looking for the start of arithmetic.  If the
	 * next previous character is a CTLESC character, then we
	 * have to rescan starting from the beginning since CTLESC
	 * characters have to be processed left to right.
	 */
	CHECKSTRSPACE(10, expdest);
	USTPUTC('\0', expdest);
	start = stackblock();
	p = expdest - 1;
	while (*p != CTLARI && p >= start)
		--p;
	if (*p != CTLARI)
		error("missing CTLARI (shouldn't happen)");
	if (p > start && *(p-1) == CTLESC)
		for (p = start; *p != CTLARI; p++)
			if (*p == CTLESC)
				p++;

	if (p[1] == '"')
		quoted=1;
	else
		quoted=0;
	begoff = p - start;
	removerecordregions(begoff);
	if (quotes)
		rmescapes(p+2);
	result = arith(p+2);
	fmtstr(p, 12, "%d", result);

	while (*p++)
		;

	if (quoted == 0)
		recordregion(begoff, p - 1 - start, 0);
	result = expdest - p + 1;
	STADJUST(-result, expdest);
}
#endif

/*
 * Expand stuff in backwards quotes.
 */

static void
expbackq(cmd, quoted, flag)
	union node *cmd;
	int quoted;
	int flag;
{
	volatile struct backcmd in;
	int i;
	char buf[128];
	char *p;
	char *dest = expdest;
	volatile struct ifsregion saveifs;
	struct ifsregion *volatile savelastp;
	struct nodelist *volatile saveargbackq;
	char lastc;
	int startloc = dest - stackblock();
	char const *syntax = quoted? DQSYNTAX : BASESYNTAX;
	volatile int saveherefd;
	int quotes = flag & (EXP_FULL | EXP_CASE);
	struct jmploc jmploc;
	struct jmploc *volatile savehandler;
	int ex;

#if __GNUC__
	/* Avoid longjmp clobbering */
	(void) &dest;
	(void) &syntax;
#endif

	in.fd = -1;
	in.buf = 0;
	in.jp = 0;

	INTOFF;
	saveifs = ifsfirst;
	savelastp = ifslastp;
	saveargbackq = argbackq;
	saveherefd = herefd;
	herefd = -1;
	if ((ex = setjmp(jmploc.loc))) {
		goto err1;
	}
	savehandler = handler;
	handler = &jmploc;
	INTON;
	p = grabstackstr(dest);
	evalbackcmd(cmd, (struct backcmd *) &in);
	ungrabstackstr(p, dest);
err1:
	INTOFF;
	ifsfirst = saveifs;
	ifslastp = savelastp;
	argbackq = saveargbackq;
	herefd = saveherefd;
	if (ex) {
		goto err2;
	}

	p = in.buf;
	lastc = '\0';
	for (;;) {
		if (--in.nleft < 0) {
			if (in.fd < 0)
				break;
			while ((i = read(in.fd, buf, sizeof buf)) < 0 && errno == EINTR);
			TRACE(("expbackq: read returns %d\n", i));
			if (i <= 0)
				break;
			p = buf;
			in.nleft = i - 1;
		}
		lastc = *p++;
		if (lastc != '\0') {
			if (quotes && syntax[(int)lastc] == CCTL)
				STPUTC(CTLESC, dest);
			STPUTC(lastc, dest);
		}
	}

	/* Eat all trailing newlines */
	for (; dest > stackblock() && dest[-1] == '\n';)
		STUNPUTC(dest);

err2:
	if (in.fd >= 0)
		close(in.fd);
	if (in.buf)
		ckfree(in.buf);
	if (in.jp)
		exitstatus = waitforjob(in.jp);
	handler = savehandler;
	if (ex) {
		longjmp(handler->loc, 1);
	}
	if (quoted == 0)
		recordregion(startloc, dest - stackblock(), 0);
	TRACE(("evalbackq: size=%d: \"%.*s\"\n",
		(dest - stackblock()) - startloc,
		(dest - stackblock()) - startloc,
		stackblock() + startloc));
	expdest = dest;
	INTON;
}

static int
subevalvar(p, str, strloc, subtype, startloc, varflags, quotes)
	char *p;
	char *str;
	int strloc;
	int subtype;
	int startloc;
	int varflags;
	int quotes;
{
	char *startp;
	char *loc = NULL;
	char *q;
	int c = 0;
	int saveherefd = herefd;
	struct nodelist *saveargbackq = argbackq;
	int amount;

	herefd = -1;
	argstr(p, subtype != VSASSIGN && subtype != VSQUESTION ? EXP_CASE : 0);
	STACKSTRNUL(expdest);
	herefd = saveherefd;
	argbackq = saveargbackq;
	startp = stackblock() + startloc;
	if (str == NULL)
	    str = stackblock() + strloc;

	switch (subtype) {
	case VSASSIGN:
		setvar(str, startp, 0);
		amount = startp - expdest;
		STADJUST(amount, expdest);
		varflags &= ~VSNUL;
		if (c != 0)
			*loc = c;
		return 1;

	case VSQUESTION:
		if (*p != CTLENDVAR) {
			outfmt(&errout, snlfmt, startp);
			error((char *)NULL);
		}
		error("%.*s: parameter %snot set", p - str - 1,
		      str, (varflags & VSNUL) ? "null or "
					      : nullstr);
		/* NOTREACHED */

	case VSTRIMLEFT:
		for (loc = startp; loc < str; loc++) {
			c = *loc;
			*loc = '\0';
			if (patmatch2(str, startp, quotes))
				goto recordleft;
			*loc = c;
			if (quotes && *loc == CTLESC)
				loc++;
		}
		return 0;

	case VSTRIMLEFTMAX:
		for (loc = str - 1; loc >= startp;) {
			c = *loc;
			*loc = '\0';
			if (patmatch2(str, startp, quotes))
				goto recordleft;
			*loc = c;
			loc--;
			if (quotes && loc > startp && *(loc - 1) == CTLESC) {
				for (q = startp; q < loc; q++)
					if (*q == CTLESC)
						q++;
				if (q > loc)
					loc--;
			}
		}
		return 0;

	case VSTRIMRIGHT:
		for (loc = str - 1; loc >= startp;) {
			if (patmatch2(str, loc, quotes))
				goto recordright;
			loc--;
			if (quotes && loc > startp && *(loc - 1) == CTLESC) {
				for (q = startp; q < loc; q++)
					if (*q == CTLESC)
						q++;
				if (q > loc)
					loc--;
			}
		}
		return 0;

	case VSTRIMRIGHTMAX:
		for (loc = startp; loc < str - 1; loc++) {
			if (patmatch2(str, loc, quotes))
				goto recordright;
			if (quotes && *loc == CTLESC)
				loc++;
		}
		return 0;

#ifdef DEBUG
	default:
		abort();
#endif
	}

recordleft:
	*loc = c;
	amount = ((str - 1) - (loc - startp)) - expdest;
	STADJUST(amount, expdest);
	while (loc != str - 1)
		*startp++ = *loc++;
	return 1;

recordright:
	amount = loc - expdest;
	STADJUST(amount, expdest);
	STPUTC('\0', expdest);
	STADJUST(-1, expdest);
	return 1;
}


/*
 * Expand a variable, and return a pointer to the next character in the
 * input string.
 */

static char *
evalvar(p, flag)
	char *p;
	int flag;
{
	int subtype;
	int varflags;
	char *var;
	char *val;
	int patloc;
	int c;
	int set;
	int special;
	int startloc;
	int varlen;
	int easy;
	int quotes = flag & (EXP_FULL | EXP_CASE);

	varflags = *p++;
	subtype = varflags & VSTYPE;
	var = p;
	special = 0;
	if (! is_name(*p))
		special = 1;
	p = strchr(p, '=') + 1;
again: /* jump here after setting a variable with ${var=text} */
	if (special) {
		set = varisset(var, varflags & VSNUL);
		val = NULL;
	} else {
		val = lookupvar(var);
		if (val == NULL || ((varflags & VSNUL) && val[0] == '\0')) {
			val = NULL;
			set = 0;
		} else
			set = 1;
	}
	varlen = 0;
	startloc = expdest - stackblock();
	if (set && subtype != VSPLUS) {
		/* insert the value of the variable */
		if (special) {
			varvalue(var, varflags & VSQUOTE, flag);
			if (subtype == VSLENGTH) {
				varlen = expdest - stackblock() - startloc;
				STADJUST(-varlen, expdest);
			}
		} else {
			if (subtype == VSLENGTH) {
				varlen = strlen(val);
			} else {
				strtodest(
					val,
					varflags & VSQUOTE ?
						DQSYNTAX : BASESYNTAX,
					quotes
				);
			}
		}
	}

	if (subtype == VSPLUS)
		set = ! set;

	easy = ((varflags & VSQUOTE) == 0 ||
		(*var == '@' && shellparam.nparam != 1));


	switch (subtype) {
	case VSLENGTH:
		expdest = cvtnum(varlen, expdest);
		goto record;

	case VSNORMAL:
		if (!easy)
			break;
record:
		recordregion(startloc, expdest - stackblock(),
			     varflags & VSQUOTE);
		break;

	case VSPLUS:
	case VSMINUS:
		if (!set) {
			argstr(p, flag);
			break;
		}
		if (easy)
			goto record;
		break;

	case VSTRIMLEFT:
	case VSTRIMLEFTMAX:
	case VSTRIMRIGHT:
	case VSTRIMRIGHTMAX:
		if (!set)
			break;
		/*
		 * Terminate the string and start recording the pattern
		 * right after it
		 */
		STPUTC('\0', expdest);
		patloc = expdest - stackblock();
		if (subevalvar(p, NULL, patloc, subtype,
			       startloc, varflags, quotes) == 0) {
			int amount = (expdest - stackblock() - patloc) + 1;
			STADJUST(-amount, expdest);
		}
		/* Remove any recorded regions beyond start of variable */
		removerecordregions(startloc);
		goto record;

	case VSASSIGN:
	case VSQUESTION:
		if (!set) {
			if (subevalvar(p, var, 0, subtype, startloc,
				       varflags, quotes)) {
				varflags &= ~VSNUL;
				/*
				 * Remove any recorded regions beyond
				 * start of variable
				 */
				removerecordregions(startloc);
				goto again;
			}
			break;
		}
		if (easy)
			goto record;
		break;

#ifdef DEBUG
	default:
		abort();
#endif
	}

	if (subtype != VSNORMAL) {      /* skip to end of alternative */
		int nesting = 1;
		for (;;) {
			if ((c = *p++) == CTLESC)
				p++;
			else if (c == CTLBACKQ || c == (CTLBACKQ|CTLQUOTE)) {
				if (set)
					argbackq = argbackq->next;
			} else if (c == CTLVAR) {
				if ((*p++ & VSTYPE) != VSNORMAL)
					nesting++;
			} else if (c == CTLENDVAR) {
				if (--nesting == 0)
					break;
			}
		}
	}
	return p;
}

/*
 * Test whether a specialized variable is set.
 */

static int
varisset(name, nulok)
	char *name;
	int nulok;
{
	if (*name == '!')
		return backgndpid != -1;
	else if (*name == '@' || *name == '*') {
		if (*shellparam.p == NULL)
			return 0;

		if (nulok) {
			char **av;

			for (av = shellparam.p; *av; av++)
				if (**av != '\0')
					return 1;
			return 0;
		}
	} else if (is_digit(*name)) {
		char *ap;
		int num = atoi(name);

		if (num > shellparam.nparam)
			return 0;

		if (num == 0)
			ap = arg0;
		else
			ap = shellparam.p[num - 1];

		if (nulok && (ap == NULL || *ap == '\0'))
			return 0;
	}
	return 1;
}

/*
 * Put a string on the stack.
 */

static void
strtodest(p, syntax, quotes)
	const char *p;
	const char *syntax;
	int quotes;
{
	while (*p) {
		if (quotes && syntax[(int) *p] == CCTL)
			STPUTC(CTLESC, expdest);
		STPUTC(*p++, expdest);
	}
}

/*
 * Add the value of a specialized variable to the stack string.
 */

static void
varvalue(name, quoted, flags)
	char *name;
	int quoted;
	int flags;
{
	int num;
	char *p;
	int i;
	int sep;
	int sepq = 0;
	char **ap;
	char const *syntax;
	int allow_split = flags & EXP_FULL;
	int quotes = flags & (EXP_FULL | EXP_CASE);

	syntax = quoted ? DQSYNTAX : BASESYNTAX;
	switch (*name) {
	case '$':
		num = rootpid;
		goto numvar;
	case '?':
		num = oexitstatus;
		goto numvar;
	case '#':
		num = shellparam.nparam;
		goto numvar;
	case '!':
		num = backgndpid;
numvar:
		expdest = cvtnum(num, expdest);
		break;
	case '-':
		for (i = 0 ; i < NOPTS ; i++) {
			if (optent_val(i))
				STPUTC(optent_letter(optlist[i]), expdest);
		}
		break;
	case '@':
		if (allow_split && quoted) {
			sep = 1 << CHAR_BIT;
			goto param;
		}
		/* fall through */
	case '*':
		sep = ifsset() ? ifsval()[0] : ' ';
		if (quotes) {
			sepq = syntax[(int) sep] == CCTL;
		}
param:
		for (ap = shellparam.p ; (p = *ap++) != NULL ; ) {
			strtodest(p, syntax, quotes);
			if (*ap && sep) {
				if (sepq)
					STPUTC(CTLESC, expdest);
				STPUTC(sep, expdest);
			}
		}
		break;
	case '0':
		strtodest(arg0, syntax, quotes);
		break;
	default:
		num = atoi(name);
		if (num > 0 && num <= shellparam.nparam) {
			strtodest(shellparam.p[num - 1], syntax, quotes);
		}
		break;
	}
}


/*
 * Record the fact that we have to scan this region of the
 * string for IFS characters.
 */

static void
recordregion(start, end, nulonly)
	int start;
	int end;
	int nulonly;
{
	struct ifsregion *ifsp;

	if (ifslastp == NULL) {
		ifsp = &ifsfirst;
	} else {
		INTOFF;
		ifsp = (struct ifsregion *)ckmalloc(sizeof (struct ifsregion));
		ifsp->next = NULL;
		ifslastp->next = ifsp;
		INTON;
	}
	ifslastp = ifsp;
	ifslastp->begoff = start;
	ifslastp->endoff = end;
	ifslastp->nulonly = nulonly;
}



/*
 * Break the argument string into pieces based upon IFS and add the
 * strings to the argument list.  The regions of the string to be
 * searched for IFS characters have been stored by recordregion.
 */
static void
ifsbreakup(string, arglist)
	char *string;
	struct arglist *arglist;
	{
	struct ifsregion *ifsp;
	struct strlist *sp;
	char *start;
	char *p;
	char *q;
	const char *ifs, *realifs;
	int ifsspc;
	int nulonly;


	start = string;
	ifsspc = 0;
	nulonly = 0;
	realifs = ifsset() ? ifsval() : defifs;
	if (ifslastp != NULL) {
		ifsp = &ifsfirst;
		do {
			p = string + ifsp->begoff;
			nulonly = ifsp->nulonly;
			ifs = nulonly ? nullstr : realifs;
			ifsspc = 0;
			while (p < string + ifsp->endoff) {
				q = p;
				if (*p == CTLESC)
					p++;
				if (strchr(ifs, *p)) {
					if (!nulonly)
						ifsspc = (strchr(defifs, *p) != NULL);
					/* Ignore IFS whitespace at start */
					if (q == start && ifsspc) {
						p++;
						start = p;
						continue;
					}
					*q = '\0';
					sp = (struct strlist *)stalloc(sizeof *sp);
					sp->text = start;
					*arglist->lastp = sp;
					arglist->lastp = &sp->next;
					p++;
					if (!nulonly) {
						for (;;) {
							if (p >= string + ifsp->endoff) {
								break;
							}
							q = p;
							if (*p == CTLESC)
								p++;
							if (strchr(ifs, *p) == NULL ) {
								p = q;
								break;
							} else if (strchr(defifs, *p) == NULL) {
								if (ifsspc) {
									p++;
									ifsspc = 0;
								} else {
									p = q;
									break;
								}
							} else
								p++;
						}
					}
					start = p;
				} else
					p++;
			}
		} while ((ifsp = ifsp->next) != NULL);
		if (!(*start || (!ifsspc && start > string && nulonly))) {
			return;
		}
	}

	sp = (struct strlist *)stalloc(sizeof *sp);
	sp->text = start;
	*arglist->lastp = sp;
	arglist->lastp = &sp->next;
}

static void
ifsfree()
{
	while (ifsfirst.next != NULL) {
		struct ifsregion *ifsp;
		INTOFF;
		ifsp = ifsfirst.next->next;
		ckfree(ifsfirst.next);
		ifsfirst.next = ifsp;
		INTON;
	}
	ifslastp = NULL;
	ifsfirst.next = NULL;
}

/*
 * Add a file name to the list.
 */

static void
addfname(const char *name)
{
	char *p;
	struct strlist *sp;

	p = sstrdup(name);
	sp = (struct strlist *)stalloc(sizeof *sp);
	sp->text = p;
	*exparg.lastp = sp;
	exparg.lastp = &sp->next;
}

/*
 * Expand shell metacharacters.  At this point, the only control characters
 * should be escapes.  The results are stored in the list exparg.
 */

#if defined(__GLIBC__) && !defined(FNMATCH_BROKEN) && !defined(GLOB_BROKEN)
static void
expandmeta(str, flag)
	struct strlist *str;
	int flag;
{
	const char *p;
	glob_t pglob;
	/* TODO - EXP_REDIR */

	while (str) {
		if (fflag)
			goto nometa;
		p = preglob(str->text);
		INTOFF;
		switch (glob(p, GLOB_NOMAGIC, 0, &pglob)) {
		case 0:
			if (!(pglob.gl_flags & GLOB_MAGCHAR))
				goto nometa2;
			addglob(&pglob);
			globfree(&pglob);
			INTON;
			break;
		case GLOB_NOMATCH:
nometa2:
			globfree(&pglob);
			INTON;
nometa:
			*exparg.lastp = str;
			rmescapes(str->text);
			exparg.lastp = &str->next;
			break;
		default:        /* GLOB_NOSPACE */
			error("Out of space");
		}
		str = str->next;
	}
}


/*
 * Add the result of glob(3) to the list.
 */

static void
addglob(pglob)
	const glob_t *pglob;
{
	char **p = pglob->gl_pathv;

	do {
		addfname(*p);
	} while (*++p);
}


#else   /* defined(__GLIBC__) && !defined(FNMATCH_BROKEN) && !defined(GLOB_BROKEN) */
static char *expdir;


static void
expandmeta(str, flag)
	struct strlist *str;
	int flag;
{
	char *p;
	struct strlist **savelastp;
	struct strlist *sp;
	char c;
	/* TODO - EXP_REDIR */

	while (str) {
		if (fflag)
			goto nometa;
		p = str->text;
		for (;;) {                      /* fast check for meta chars */
			if ((c = *p++) == '\0')
				goto nometa;
			if (c == '*' || c == '?' || c == '[' || c == '!')
				break;
		}
		savelastp = exparg.lastp;
		INTOFF;
		if (expdir == NULL) {
			int i = strlen(str->text);
			expdir = ckmalloc(i < 2048 ? 2048 : i); /* XXX */
		}

		expmeta(expdir, str->text);
		ckfree(expdir);
		expdir = NULL;
		INTON;
		if (exparg.lastp == savelastp) {
			/*
			 * no matches
			 */
nometa:
			*exparg.lastp = str;
			rmescapes(str->text);
			exparg.lastp = &str->next;
		} else {
			*exparg.lastp = NULL;
			*savelastp = sp = expsort(*savelastp);
			while (sp->next != NULL)
				sp = sp->next;
			exparg.lastp = &sp->next;
		}
		str = str->next;
	}
}


/*
 * Do metacharacter (i.e. *, ?, [...]) expansion.
 */

static void
expmeta(enddir, name)
	char *enddir;
	char *name;
	{
	char *p;
	const char *cp;
	char *q;
	char *start;
	char *endname;
	int metaflag;
	struct stat statb;
	DIR *dirp;
	struct dirent *dp;
	int atend;
	int matchdot;

	metaflag = 0;
	start = name;
	for (p = name ; ; p++) {
		if (*p == '*' || *p == '?')
			metaflag = 1;
		else if (*p == '[') {
			q = p + 1;
			if (*q == '!')
				q++;
			for (;;) {
				while (*q == CTLQUOTEMARK)
					q++;
				if (*q == CTLESC)
					q++;
				if (*q == '/' || *q == '\0')
					break;
				if (*++q == ']') {
					metaflag = 1;
					break;
				}
			}
		} else if (*p == '!' && p[1] == '!'     && (p == name || p[-1] == '/')) {
			metaflag = 1;
		} else if (*p == '\0')
			break;
		else if (*p == CTLQUOTEMARK)
			continue;
		else if (*p == CTLESC)
			p++;
		if (*p == '/') {
			if (metaflag)
				break;
			start = p + 1;
		}
	}
	if (metaflag == 0) {    /* we've reached the end of the file name */
		if (enddir != expdir)
			metaflag++;
		for (p = name ; ; p++) {
			if (*p == CTLQUOTEMARK)
				continue;
			if (*p == CTLESC)
				p++;
			*enddir++ = *p;
			if (*p == '\0')
				break;
		}
		if (metaflag == 0 || lstat(expdir, &statb) >= 0)
			addfname(expdir);
		return;
	}
	endname = p;
	if (start != name) {
		p = name;
		while (p < start) {
			while (*p == CTLQUOTEMARK)
				p++;
			if (*p == CTLESC)
				p++;
			*enddir++ = *p++;
		}
	}
	if (enddir == expdir) {
		cp = ".";
	} else if (enddir == expdir + 1 && *expdir == '/') {
		cp = "/";
	} else {
		cp = expdir;
		enddir[-1] = '\0';
	}
	if ((dirp = opendir(cp)) == NULL)
		return;
	if (enddir != expdir)
		enddir[-1] = '/';
	if (*endname == 0) {
		atend = 1;
	} else {
		atend = 0;
		*endname++ = '\0';
	}
	matchdot = 0;
	p = start;
	while (*p == CTLQUOTEMARK)
		p++;
	if (*p == CTLESC)
		p++;
	if (*p == '.')
		matchdot++;
	while (! int_pending() && (dp = readdir(dirp)) != NULL) {
		if (dp->d_name[0] == '.' && ! matchdot)
			continue;
		if (patmatch(start, dp->d_name, 0)) {
			if (atend) {
				strcpy(enddir, dp->d_name);
				addfname(expdir);
			} else {
				for (p = enddir, cp = dp->d_name;
				     (*p++ = *cp++) != '\0';)
					continue;
				p[-1] = '/';
				expmeta(p, endname);
			}
		}
	}
	closedir(dirp);
	if (! atend)
		endname[-1] = '/';
}
#endif  /* defined(__GLIBC__) && !defined(FNMATCH_BROKEN) && !defined(GLOB_BROKEN) */



#if !(defined(__GLIBC__) && !defined(FNMATCH_BROKEN) && !defined(GLOB_BROKEN))
/*
 * Sort the results of file name expansion.  It calculates the number of
 * strings to sort and then calls msort (short for merge sort) to do the
 * work.
 */

static struct strlist *
expsort(str)
	struct strlist *str;
	{
	int len;
	struct strlist *sp;

	len = 0;
	for (sp = str ; sp ; sp = sp->next)
		len++;
	return msort(str, len);
}


static struct strlist *
msort(list, len)
	struct strlist *list;
	int len;
{
	struct strlist *p, *q = NULL;
	struct strlist **lpp;
	int half;
	int n;

	if (len <= 1)
		return list;
	half = len >> 1;
	p = list;
	for (n = half ; --n >= 0 ; ) {
		q = p;
		p = p->next;
	}
	q->next = NULL;                 /* terminate first half of list */
	q = msort(list, half);          /* sort first half of list */
	p = msort(p, len - half);               /* sort second half */
	lpp = &list;
	for (;;) {
		if (strcmp(p->text, q->text) < 0) {
			*lpp = p;
			lpp = &p->next;
			if ((p = *lpp) == NULL) {
				*lpp = q;
				break;
			}
		} else {
			*lpp = q;
			lpp = &q->next;
			if ((q = *lpp) == NULL) {
				*lpp = p;
				break;
			}
		}
	}
	return list;
}
#endif



/*
 * Returns true if the pattern matches the string.
 */

#if defined(__GLIBC__) && !defined(FNMATCH_BROKEN)
/* squoted: string might have quote chars */
static int
patmatch(char *pattern, char *string, int squoted)
{
	const char *p;
	char *q;

	p = preglob(pattern);
	q = squoted ? _rmescapes(string, RMESCAPE_ALLOC) : string;

	return !fnmatch(p, q, 0);
}


static int
patmatch2(char *pattern, char *string, int squoted)
{
	char *p;
	int res;

	sstrnleft--;
	p = grabstackstr(expdest);
	res = patmatch(pattern, string, squoted);
	ungrabstackstr(p, expdest);
	return res;
}
#else
static int
patmatch(char *pattern, char *string, int squoted) {
	return pmatch(pattern, string, squoted);
}


static int
pmatch(char *pattern, char *string, int squoted)
{
	char *p, *q;
	char c;

	p = pattern;
	q = string;
	for (;;) {
		switch (c = *p++) {
		case '\0':
			goto breakloop;
		case CTLESC:
			if (squoted && *q == CTLESC)
				q++;
			if (*q++ != *p++)
				return 0;
			break;
		case CTLQUOTEMARK:
			continue;
		case '?':
			if (squoted && *q == CTLESC)
				q++;
			if (*q++ == '\0')
				return 0;
			break;
		case '*':
			c = *p;
			while (c == CTLQUOTEMARK || c == '*')
				c = *++p;
			if (c != CTLESC &&  c != CTLQUOTEMARK &&
			    c != '?' && c != '*' && c != '[') {
				while (*q != c) {
					if (squoted && *q == CTLESC &&
					    q[1] == c)
						break;
					if (*q == '\0')
						return 0;
					if (squoted && *q == CTLESC)
						q++;
					q++;
				}
			}
			do {
				if (pmatch(p, q, squoted))
					return 1;
				if (squoted && *q == CTLESC)
					q++;
			} while (*q++ != '\0');
			return 0;
		case '[': {
			char *endp;
			int invert, found;
			char chr;

			endp = p;
			if (*endp == '!')
				endp++;
			for (;;) {
				while (*endp == CTLQUOTEMARK)
					endp++;
				if (*endp == '\0')
					goto dft;               /* no matching ] */
				if (*endp == CTLESC)
					endp++;
				if (*++endp == ']')
					break;
			}
			invert = 0;
			if (*p == '!') {
				invert++;
				p++;
			}
			found = 0;
			chr = *q++;
			if (squoted && chr == CTLESC)
				chr = *q++;
			if (chr == '\0')
				return 0;
			c = *p++;
			do {
				if (c == CTLQUOTEMARK)
					continue;
				if (c == CTLESC)
					c = *p++;
				if (*p == '-' && p[1] != ']') {
					p++;
					while (*p == CTLQUOTEMARK)
						p++;
					if (*p == CTLESC)
						p++;
					if (chr >= c && chr <= *p)
						found = 1;
					p++;
				} else {
					if (chr == c)
						found = 1;
				}
			} while ((c = *p++) != ']');
			if (found == invert)
				return 0;
			break;
		}
dft:            default:
			if (squoted && *q == CTLESC)
				q++;
			if (*q++ != c)
				return 0;
			break;
		}
	}
breakloop:
	if (*q != '\0')
		return 0;
	return 1;
}
#endif



/*
 * Remove any CTLESC characters from a string.
 */

#if defined(__GLIBC__) && !defined(FNMATCH_BROKEN)
static char *
_rmescapes(char *str, int flag)
{
	char *p, *q, *r;
	static const char qchars[] = { CTLESC, CTLQUOTEMARK, 0 };

	p = strpbrk(str, qchars);
	if (!p) {
		return str;
	}
	q = p;
	r = str;
	if (flag & RMESCAPE_ALLOC) {
		size_t len = p - str;
		q = r = stalloc(strlen(p) + len + 1);
		if (len > 0) {
#ifdef _GNU_SOURCE
			q = mempcpy(q, str, len);
#else
			memcpy(q, str, len);
			q += len;
#endif
		}
	}
	while (*p) {
		if (*p == CTLQUOTEMARK) {
			p++;
			continue;
		}
		if (*p == CTLESC) {
			p++;
			if (flag & RMESCAPE_GLOB && *p != '/') {
				*q++ = '\\';
			}
		}
		*q++ = *p++;
	}
	*q = '\0';
	return r;
}
#else
static void
rmescapes(str)
	char *str;
{
	char *p, *q;

	p = str;
	while (*p != CTLESC && *p != CTLQUOTEMARK) {
		if (*p++ == '\0')
			return;
	}
	q = p;
	while (*p) {
		if (*p == CTLQUOTEMARK) {
			p++;
			continue;
		}
		if (*p == CTLESC)
			p++;
		*q++ = *p++;
	}
	*q = '\0';
}
#endif



/*
 * See if a pattern matches in a case statement.
 */

static int
casematch(union node *pattern, const char *val)
{
	struct stackmark smark;
	int result;
	char *p;

	setstackmark(&smark);
	argbackq = pattern->narg.backquote;
	STARTSTACKSTR(expdest);
	ifslastp = NULL;
	argstr(pattern->narg.text, EXP_TILDE | EXP_CASE);
	STPUTC('\0', expdest);
	p = grabstackstr(expdest);
	result = patmatch(p, (char *)val, 0);
	popstackmark(&smark);
	return result;
}

/*
 * Our own itoa().
 */

static char *
cvtnum(num, buf)
	int num;
	char *buf;
	{
	int len;

	CHECKSTRSPACE(32, buf);
	len = sprintf(buf, "%d", num);
	STADJUST(len, buf);
	return buf;
}
/*
 * Editline and history functions (and glue).
 */
static int histcmd(argc, argv)
	int argc;
	char **argv;
{
	error("not compiled with history support");
	/* NOTREACHED */
}


static int whichprompt;         /* 1 == PS1, 2 == PS2 */


struct redirtab {
	struct redirtab *next;
	short renamed[10];
};

static struct redirtab *redirlist;

extern char **environ;



/*
 * Initialization code.
 */

static void
init(void) {

      /* from cd.c: */
      {
	      setpwd(0, 0);
      }

      /* from input.c: */
      {
	      basepf.nextc = basepf.buf = basebuf;
      }

      /* from output.c: */
      {
#ifdef USE_GLIBC_STDIO
	      initstreams();
#endif
      }

      /* from var.c: */
      {
	      char **envp;
	      char ppid[32];

	      initvar();
	      for (envp = environ ; *envp ; envp++) {
		      if (strchr(*envp, '=')) {
			      setvareq(*envp, VEXPORT|VTEXTFIXED);
		      }
	      }

	      fmtstr(ppid, sizeof(ppid), "%d", (int) getppid());
	      setvar("PPID", ppid, 0);
      }
}



/*
 * This routine is called when an error or an interrupt occurs in an
 * interactive shell and control is returned to the main command loop.
 */

#ifdef ASH_ALIAS
/* 1 == check for aliases, 2 == also check for assignments */
static int checkalias;
#endif

static void
reset(void) {

      /* from eval.c: */
      {
	      evalskip = 0;
	      loopnest = 0;
	      funcnest = 0;
      }

      /* from input.c: */
      {
	      if (exception != EXSHELLPROC)
		      parselleft = parsenleft = 0;      /* clear input buffer */
	      popallfiles();
      }

      /* from parser.c: */
      {
	      tokpushback = 0;
	      checkkwd = 0;
#ifdef ASH_ALIAS
	      checkalias = 0;
#endif
      }

      /* from redir.c: */
      {
	      while (redirlist)
		      popredir();
      }

      /* from output.c: */
      {
	      out1 = &output;
	      out2 = &errout;
#ifdef USE_GLIBC_STDIO
	      if (memout.stream != NULL)
		      __closememout();
#endif
	      if (memout.buf != NULL) {
		      ckfree(memout.buf);
		      memout.buf = NULL;
	      }
      }
}



/*
 * This file implements the input routines used by the parser.
 */

#ifdef BB_FEATURE_COMMAND_EDITING
unsigned int shell_context;
static const char * cmdedit_prompt;
static inline void putprompt(const char *s) {
    cmdedit_prompt = s;
}
#else
static inline void putprompt(const char *s) {
    out2str(s);
}
#endif

#define EOF_NLEFT -99           /* value of parsenleft when EOF pushed back */



/*
 * Same as pgetc(), but ignores PEOA.
 */

#ifdef ASH_ALIAS
static int
pgetc2()
{
	int c;
	do {
		c = pgetc_macro();
	} while (c == PEOA);
	return c;
}
#else
static inline int pgetc2() { return pgetc_macro(); }
#endif

/*
 * Read a line from the script.
 */

static char *
pfgets(char *line, int len)
{
	char *p = line;
	int nleft = len;
	int c;

	while (--nleft > 0) {
		c = pgetc2();
		if (c == PEOF) {
			if (p == line)
				return NULL;
			break;
		}
		*p++ = c;
		if (c == '\n')
			break;
	}
	*p = '\0';
	return line;
}

static int
preadfd(void)
{
    int nr;
    char *buf =  parsefile->buf;
    parsenextc = buf;

retry:
#ifdef BB_FEATURE_COMMAND_EDITING
	{
	    if (parsefile->fd)
		nr = read(parsefile->fd, buf, BUFSIZ - 1);
	    else {
		do {
		    cmdedit_read_input((char*)cmdedit_prompt, buf);
		    nr = strlen(buf);
		} while (nr <=0 || shell_context);
		cmdedit_terminate();
	    }
	}
#else
	nr = read(parsefile->fd, buf, BUFSIZ - 1);
#endif

	if (nr < 0) {
		if (errno == EINTR)
			goto retry;
		if (parsefile->fd == 0 && errno == EWOULDBLOCK) {
			int flags = fcntl(0, F_GETFL, 0);
			if (flags >= 0 && flags & O_NONBLOCK) {
				flags &=~ O_NONBLOCK;
				if (fcntl(0, F_SETFL, flags) >= 0) {
					out2str("sh: turning off NDELAY mode\n");
					goto retry;
				}
			}
		}
	}
	return nr;
}

static void
popstring(void)
{
	struct strpush *sp = parsefile->strpush;

	INTOFF;
#ifdef ASH_ALIAS
	if (sp->ap) {
		if (parsenextc[-1] == ' ' || parsenextc[-1] == '\t') {
			if (!checkalias) {
				checkalias = 1;
			}
		}
		if (sp->string != sp->ap->val) {
			ckfree(sp->string);
		}

		sp->ap->flag &= ~ALIASINUSE;
		if (sp->ap->flag & ALIASDEAD) {
			unalias(sp->ap->name);
		}
	}
#endif
	parsenextc = sp->prevstring;
	parsenleft = sp->prevnleft;
/*dprintf("*** calling popstring: restoring to '%s'\n", parsenextc);*/
	parsefile->strpush = sp->prev;
	if (sp != &(parsefile->basestrpush))
		ckfree(sp);
	INTON;
}


/*
 * Refill the input buffer and return the next input character:
 *
 * 1) If a string was pushed back on the input, pop it;
 * 2) If an EOF was pushed back (parsenleft == EOF_NLEFT) or we are reading
 *    from a string so we can't refill the buffer, return EOF.
 * 3) If the is more stuff in this buffer, use it else call read to fill it.
 * 4) Process input up to the next newline, deleting nul characters.
 */

static int
preadbuffer(void)
{
	char *p, *q;
	int more;
	char savec;

	while (parsefile->strpush) {
#ifdef ASH_ALIAS
		if (parsenleft == -1 && parsefile->strpush->ap &&
			parsenextc[-1] != ' ' && parsenextc[-1] != '\t') {
			return PEOA;
		}
#endif
		popstring();
		if (--parsenleft >= 0)
			return (*parsenextc++);
	}
	if (parsenleft == EOF_NLEFT || parsefile->buf == NULL)
		return PEOF;
	flushout(&output);
#ifdef FLUSHERR
	flushout(&errout);
#endif

again:
	if (parselleft <= 0) {
		if ((parselleft = preadfd()) <= 0) {
			parselleft = parsenleft = EOF_NLEFT;
			return PEOF;
		}
	}

	q = p = parsenextc;

	/* delete nul characters */
	for (more = 1; more;) {
		switch (*p) {
		case '\0':
			p++;    /* Skip nul */
			goto check;


		case '\n':
			parsenleft = q - parsenextc;
			more = 0; /* Stop processing here */
			break;
		}

		*q++ = *p++;
check:
		if (--parselleft <= 0 && more) {
			parsenleft = q - parsenextc - 1;
			if (parsenleft < 0)
				goto again;
			more = 0;
		}
	}

	savec = *q;
	*q = '\0';

	if (vflag) {
		out2str(parsenextc);
#ifdef FLUSHERR
		flushout(out2);
#endif
	}

	*q = savec;

	return *parsenextc++;
}


/*
 * Push a string back onto the input at this current parsefile level.
 * We handle aliases this way.
 */
static void
pushstring(char *s, int len, void *ap)
{
	struct strpush *sp;

	INTOFF;
/*dprintf("*** calling pushstring: %s, %d\n", s, len);*/
	if (parsefile->strpush) {
		sp = ckmalloc(sizeof (struct strpush));
		sp->prev = parsefile->strpush;
		parsefile->strpush = sp;
	} else
		sp = parsefile->strpush = &(parsefile->basestrpush);
	sp->prevstring = parsenextc;
	sp->prevnleft = parsenleft;
#ifdef ASH_ALIAS
	sp->ap = (struct alias *)ap;
	if (ap) {
		((struct alias *)ap)->flag |= ALIASINUSE;
		sp->string = s;
	}
#endif
	parsenextc = s;
	parsenleft = len;
	INTON;
}




/*
 * Like setinputfile, but takes input from a string.
 */

static void
setinputstring(string)
	char *string;
	{
	INTOFF;
	pushfile();
	parsenextc = string;
	parsenleft = strlen(string);
	parsefile->buf = NULL;
	plinno = 1;
	INTON;
}



/*
 * To handle the "." command, a stack of input files is used.  Pushfile
 * adds a new entry to the stack and popfile restores the previous level.
 */

static void
pushfile(void) {
	struct parsefile *pf;

	parsefile->nleft = parsenleft;
	parsefile->lleft = parselleft;
	parsefile->nextc = parsenextc;
	parsefile->linno = plinno;
	pf = (struct parsefile *)ckmalloc(sizeof (struct parsefile));
	pf->prev = parsefile;
	pf->fd = -1;
	pf->strpush = NULL;
	pf->basestrpush.prev = NULL;
	parsefile = pf;
}

#ifdef JOBS
static void restartjob (struct job *);
#endif
static void freejob (struct job *);
static struct job *getjob (const char *);
static int dowait (int, struct job *);
static int waitproc (int, int *);
static void waitonint(int);


/*
 * We keep track of whether or not fd0 has been redirected.  This is for
 * background commands, where we want to redirect fd0 to /dev/null only
 * if it hasn't already been redirected.
*/
static int fd0_redirected = 0;

/* Return true if fd 0 has already been redirected at least once.  */
static inline int
fd0_redirected_p () {
	return fd0_redirected != 0;
}

/*
 * We also keep track of where fileno2 goes.
 */
static int fileno2 = 2;

static int openredirect (union node *);
static void dupredirect (union node *, int, char[10 ]);
static int openhere (union node *);
static int noclobberopen (const char *);



#ifdef JOBS
/*
 * Turn job control on and off.
 *
 * Note:  This code assumes that the third arg to ioctl is a character
 * pointer, which is true on Berkeley systems but not System V.  Since
 * System V doesn't have job control yet, this isn't a problem now.
 */



static void setjobctl(int enable)
{
#ifdef OLD_TTY_DRIVER
	int ldisc;
#endif

	if (enable == jobctl || rootshell == 0)
		return;
	if (enable) {
		do { /* while we are in the background */
#ifdef OLD_TTY_DRIVER
			if (ioctl(fileno2, TIOCGPGRP, (char *)&initialpgrp) < 0) {
#else
			initialpgrp = tcgetpgrp(fileno2);
			if (initialpgrp < 0) {
#endif
				out2str("sh: can't access tty; job cenabletrol turned off\n");
				mflag = 0;
				return;
			}
			if (initialpgrp == -1)
				initialpgrp = getpgrp();
			else if (initialpgrp != getpgrp()) {
				killpg(initialpgrp, SIGTTIN);
				continue;
			}
		} while (0);
#ifdef OLD_TTY_DRIVER
		if (ioctl(fileno2, TIOCGETD, (char *)&ldisc) < 0 || ldisc != NTTYDISC) {
			out2str("sh: need new tty driver to run job cenabletrol; job cenabletrol turned off\n");
			mflag = 0;
			return;
		}
#endif
		setsignal(SIGTSTP);
		setsignal(SIGTTOU);
		setsignal(SIGTTIN);
		setpgid(0, rootpid);
#ifdef OLD_TTY_DRIVER
		ioctl(fileno2, TIOCSPGRP, (char *)&rootpid);
#else
		tcsetpgrp(fileno2, rootpid);
#endif
	} else { /* turning job cenabletrol off */
		setpgid(0, initialpgrp);
#ifdef OLD_TTY_DRIVER
		ioctl(fileno2, TIOCSPGRP, (char *)&initialpgrp);
#else
		tcsetpgrp(fileno2, initialpgrp);
#endif
		setsignal(SIGTSTP);
		setsignal(SIGTTOU);
		setsignal(SIGTTIN);
	}
	jobctl = enable;
}
#endif


/* A translation list so we can be polite to our users. */
static char *signal_names[NSIG + 2] = {
    "EXIT",
    "SIGHUP",
    "SIGINT",
    "SIGQUIT",
    "SIGILL",
    "SIGTRAP",
    "SIGABRT",
    "SIGBUS",
    "SIGFPE",
    "SIGKILL",
    "SIGUSR1",
    "SIGSEGV",
    "SIGUSR2",
    "SIGPIPE",
    "SIGALRM",
    "SIGTERM",
    "SIGJUNK(16)",
    "SIGCHLD",
    "SIGCONT",
    "SIGSTOP",
    "SIGTSTP",
    "SIGTTIN",
    "SIGTTOU",
    "SIGURG",
    "SIGXCPU",
    "SIGXFSZ",
    "SIGVTALRM",
    "SIGPROF",
    "SIGWINCH",
    "SIGIO",
    "SIGPWR",
    "SIGSYS",
    "SIGRTMIN",
    "SIGRTMIN+1",
    "SIGRTMIN+2",
    "SIGRTMIN+3",
    "SIGRTMIN+4",
    "SIGRTMIN+5",
    "SIGRTMIN+6",
    "SIGRTMIN+7",
    "SIGRTMIN+8",
    "SIGRTMIN+9",
    "SIGRTMIN+10",
    "SIGRTMIN+11",
    "SIGRTMIN+12",
    "SIGRTMIN+13",
    "SIGRTMIN+14",
    "SIGRTMIN+15",
    "SIGRTMAX-15",
    "SIGRTMAX-14",
    "SIGRTMAX-13",
    "SIGRTMAX-12",
    "SIGRTMAX-11",
    "SIGRTMAX-10",
    "SIGRTMAX-9",
    "SIGRTMAX-8",
    "SIGRTMAX-7",
    "SIGRTMAX-6",
    "SIGRTMAX-5",
    "SIGRTMAX-4",
    "SIGRTMAX-3",
    "SIGRTMAX-2",
    "SIGRTMAX-1",
    "SIGRTMAX",
    "DEBUG",
    (char *)0x0,
};



#ifdef JOBS
static int
killcmd(argc, argv)
	int argc;
	char **argv;
{
	int signo = -1;
	int list = 0;
	int i;
	pid_t pid;
	struct job *jp;

	if (argc <= 1) {
usage:
		error(
"Usage: kill [-s sigspec | -signum | -sigspec] [pid | job]... or\n"
"kill -l [exitstatus]"
		);
	}

	if (*argv[1] == '-') {
		signo = decode_signal(argv[1] + 1, 1);
		if (signo < 0) {
			int c;

			while ((c = nextopt("ls:")) != '\0')
				switch (c) {
				case 'l':
					list = 1;
					break;
				case 's':
					signo = decode_signal(optionarg, 1);
					if (signo < 0) {
						error(
							"invalid signal number or name: %s",
							optionarg
						);
					}
					break;
#ifdef DEBUG
				default:
					error(
	"nextopt returned character code 0%o", c);
#endif
			}
		} else
			argptr++;
	}

	if (!list && signo < 0)
		signo = SIGTERM;

	if ((signo < 0 || !*argptr) ^ list) {
		goto usage;
	}

	if (list) {
		if (!*argptr) {
			out1str("0\n");
			for (i = 1; i < NSIG; i++) {
				out1fmt(snlfmt, signal_names[i] + 3);
			}
			return 0;
		}
		signo = atoi(*argptr);
		if (signo > 128)
			signo -= 128;
		if (0 < signo && signo < NSIG)
				out1fmt(snlfmt, signal_names[signo] + 3);
		else
			error("invalid signal number or exit status: %s",
			      *argptr);
		return 0;
	}

	do {
		if (**argptr == '%') {
			jp = getjob(*argptr);
			if (jp->jobctl == 0)
				error("job %s not created under job control",
				      *argptr);
			pid = -jp->ps[0].pid;
		} else
			pid = atoi(*argptr);
		if (kill(pid, signo) != 0)
			error("%s: %m", *argptr);
	} while (*++argptr);

	return 0;
}

static int
fgcmd(argc, argv)
	int argc;
	char **argv;
{
	struct job *jp;
	int pgrp;
	int status;

	jp = getjob(argv[1]);
	if (jp->jobctl == 0)
		error("job not created under job control");
	pgrp = jp->ps[0].pid;
#ifdef OLD_TTY_DRIVER
	ioctl(fileno2, TIOCSPGRP, (char *)&pgrp);
#else
	tcsetpgrp(fileno2, pgrp);
#endif
	restartjob(jp);
	INTOFF;
	status = waitforjob(jp);
	INTON;
	return status;
}


static int
bgcmd(argc, argv)
	int argc;
	char **argv;
{
	struct job *jp;

	do {
		jp = getjob(*++argv);
		if (jp->jobctl == 0)
			error("job not created under job control");
		restartjob(jp);
	} while (--argc > 1);
	return 0;
}


static void
restartjob(jp)
	struct job *jp;
{
	struct procstat *ps;
	int i;

	if (jp->state == JOBDONE)
		return;
	INTOFF;
	killpg(jp->ps[0].pid, SIGCONT);
	for (ps = jp->ps, i = jp->nprocs ; --i >= 0 ; ps++) {
		if (WIFSTOPPED(ps->status)) {
			ps->status = -1;
			jp->state = 0;
		}
	}
	INTON;
}
#endif

static void showjobs(int change);


static int
jobscmd(argc, argv)
	int argc;
	char **argv;
{
	showjobs(0);
	return 0;
}


/*
 * Print a list of jobs.  If "change" is nonzero, only print jobs whose
 * statuses have changed since the last call to showjobs.
 *
 * If the shell is interrupted in the process of creating a job, the
 * result may be a job structure containing zero processes.  Such structures
 * will be freed here.
 */

static void
showjobs(change)
	int change;
{
	int jobno;
	int procno;
	int i;
	struct job *jp;
	struct procstat *ps;
	int col;
	char s[64];

	TRACE(("showjobs(%d) called\n", change));
	while (dowait(0, (struct job *)NULL) > 0);
	for (jobno = 1, jp = jobtab ; jobno <= njobs ; jobno++, jp++) {
		if (! jp->used)
			continue;
		if (jp->nprocs == 0) {
			freejob(jp);
			continue;
		}
		if (change && ! jp->changed)
			continue;
		procno = jp->nprocs;
		for (ps = jp->ps ; ; ps++) {    /* for each process */
			if (ps == jp->ps)
				fmtstr(s, 64, "[%d] %ld ", jobno,
				    (long)ps->pid);
			else
				fmtstr(s, 64, "    %ld ",
				    (long)ps->pid);
			out1str(s);
			col = strlen(s);
			s[0] = '\0';
			if (ps->status == -1) {
				/* don't print anything */
			} else if (WIFEXITED(ps->status)) {
				fmtstr(s, 64, "Exit %d",
				       WEXITSTATUS(ps->status));
			} else {
#ifdef JOBS
				if (WIFSTOPPED(ps->status))
					i = WSTOPSIG(ps->status);
				else /* WIFSIGNALED(ps->status) */
#endif
					i = WTERMSIG(ps->status);
				if ((i & 0x7F) < NSIG && sys_siglist[i & 0x7F])
					strcpy(s, sys_siglist[i & 0x7F]);
				else
					fmtstr(s, 64, "Signal %d", i & 0x7F);
				if (WCOREDUMP(ps->status))
					strcat(s, " (core dumped)");
			}
			out1str(s);
			col += strlen(s);
			out1fmt(
				"%*c%s\n", 30 - col >= 0 ? 30 - col : 0, ' ',
				ps->cmd
			);
			if (--procno <= 0)
				break;
		}
		jp->changed = 0;
		if (jp->state == JOBDONE) {
			freejob(jp);
		}
	}
}


/*
 * Mark a job structure as unused.
 */

static void
freejob(jp)
	struct job *jp;
	{
	struct procstat *ps;
	int i;

	INTOFF;
	for (i = jp->nprocs, ps = jp->ps ; --i >= 0 ; ps++) {
		if (ps->cmd != nullstr)
			ckfree(ps->cmd);
	}
	if (jp->ps != &jp->ps0)
		ckfree(jp->ps);
	jp->used = 0;
#ifdef JOBS
	if (curjob == jp - jobtab + 1)
		curjob = 0;
#endif
	INTON;
}



static int
waitcmd(argc, argv)
	int argc;
	char **argv;
{
	struct job *job;
	int status, retval;
	struct job *jp;

	if (--argc > 0) {
start:
		job = getjob(*++argv);
	} else {
		job = NULL;
	}
	for (;;) {      /* loop until process terminated or stopped */
		if (job != NULL) {
			if (job->state) {
				status = job->ps[job->nprocs - 1].status;
				if (! iflag)
					freejob(job);
				if (--argc) {
					goto start;
				}
				if (WIFEXITED(status))
					retval = WEXITSTATUS(status);
#ifdef JOBS
				else if (WIFSTOPPED(status))
					retval = WSTOPSIG(status) + 128;
#endif
				else {
					/* XXX: limits number of signals */
					retval = WTERMSIG(status) + 128;
				}
				return retval;
			}
		} else {
			for (jp = jobtab ; ; jp++) {
				if (jp >= jobtab + njobs) {     /* no running procs */
					return 0;
				}
				if (jp->used && jp->state == 0)
					break;
			}
		}
		if (dowait(2, 0) < 0 && errno == EINTR) {
			return 129;
		}
	}
}



/*
 * Convert a job name to a job structure.
 */

static struct job *
getjob(const char *name)
{
	int jobno;
	struct job *jp;
	int pid;
	int i;

	if (name == NULL) {
#ifdef JOBS
currentjob:
		if ((jobno = curjob) == 0 || jobtab[jobno - 1].used == 0)
			error("No current job");
		return &jobtab[jobno - 1];
#else
		error("No current job");
#endif
	} else if (name[0] == '%') {
		if (is_digit(name[1])) {
			jobno = number(name + 1);
			if (jobno > 0 && jobno <= njobs
			 && jobtab[jobno - 1].used != 0)
				return &jobtab[jobno - 1];
#ifdef JOBS
		} else if (name[1] == '%' && name[2] == '\0') {
			goto currentjob;
#endif
		} else {
			struct job *found = NULL;
			for (jp = jobtab, i = njobs ; --i >= 0 ; jp++) {
				if (jp->used && jp->nprocs > 0
				 && prefix(name + 1, jp->ps[0].cmd)) {
					if (found)
						error("%s: ambiguous", name);
					found = jp;
				}
			}
			if (found)
				return found;
		}
	} else if (is_number(name, &pid)) {
		for (jp = jobtab, i = njobs ; --i >= 0 ; jp++) {
			if (jp->used && jp->nprocs > 0
			 && jp->ps[jp->nprocs - 1].pid == pid)
				return jp;
		}
	}
	error("No such job: %s", name);
	/* NOTREACHED */
}



/*
 * Return a new job structure,
 */

static struct job *
makejob(node, nprocs)
	union node *node;
	int nprocs;
{
	int i;
	struct job *jp;

	for (i = njobs, jp = jobtab ; ; jp++) {
		if (--i < 0) {
			INTOFF;
			if (njobs == 0) {
				jobtab = ckmalloc(4 * sizeof jobtab[0]);
			} else {
				jp = ckmalloc((njobs + 4) * sizeof jobtab[0]);
				memcpy(jp, jobtab, njobs * sizeof jp[0]);
				/* Relocate `ps' pointers */
				for (i = 0; i < njobs; i++)
					if (jp[i].ps == &jobtab[i].ps0)
						jp[i].ps = &jp[i].ps0;
				ckfree(jobtab);
				jobtab = jp;
			}
			jp = jobtab + njobs;
			for (i = 4 ; --i >= 0 ; jobtab[njobs++].used = 0);
			INTON;
			break;
		}
		if (jp->used == 0)
			break;
	}
	INTOFF;
	jp->state = 0;
	jp->used = 1;
	jp->changed = 0;
	jp->nprocs = 0;
#ifdef JOBS
	jp->jobctl = jobctl;
#endif
	if (nprocs > 1) {
		jp->ps = ckmalloc(nprocs * sizeof (struct procstat));
	} else {
		jp->ps = &jp->ps0;
	}
	INTON;
	TRACE(("makejob(0x%lx, %d) returns %%%d\n", (long)node, nprocs,
	    jp - jobtab + 1));
	return jp;
}


/*
 * Fork of a subshell.  If we are doing job control, give the subshell its
 * own process group.  Jp is a job structure that the job is to be added to.
 * N is the command that will be evaluated by the child.  Both jp and n may
 * be NULL.  The mode parameter can be one of the following:
 *      FORK_FG - Fork off a foreground process.
 *      FORK_BG - Fork off a background process.
 *      FORK_NOJOB - Like FORK_FG, but don't give the process its own
 *                   process group even if job control is on.
 *
 * When job control is turned off, background processes have their standard
 * input redirected to /dev/null (except for the second and later processes
 * in a pipeline).
 */



static int
forkshell(struct job *jp, union node *n, int mode)
{
	int pid;
	int pgrp;
	const char *devnull = _PATH_DEVNULL;
	const char *nullerr = "Can't open %s";

	TRACE(("forkshell(%%%d, 0x%lx, %d) called\n", jp - jobtab, (long)n,
	    mode));
	INTOFF;
	pid = fork();
	if (pid == -1) {
		TRACE(("Fork failed, errno=%d\n", errno));
		INTON;
		error("Cannot fork");
	}
	if (pid == 0) {
		struct job *p;
		int wasroot;
		int i;

		TRACE(("Child shell %d\n", getpid()));
		wasroot = rootshell;
		rootshell = 0;
		closescript();
		INTON;
		clear_traps();
#ifdef JOBS
		jobctl = 0;             /* do job control only in root shell */
		if (wasroot && mode != FORK_NOJOB && mflag) {
			if (jp == NULL || jp->nprocs == 0)
				pgrp = getpid();
			else
				pgrp = jp->ps[0].pid;
			setpgid(0, pgrp);
			if (mode == FORK_FG) {
				/*** this causes superfluous TIOCSPGRPS ***/
#ifdef OLD_TTY_DRIVER
				if (ioctl(fileno2, TIOCSPGRP, (char *)&pgrp) < 0)
					error("TIOCSPGRP failed, errno=%d", errno);
#else
				if (tcsetpgrp(fileno2, pgrp) < 0)
					error("tcsetpgrp failed, errno=%d", errno);
#endif
			}
			setsignal(SIGTSTP);
			setsignal(SIGTTOU);
		} else if (mode == FORK_BG) {
			ignoresig(SIGINT);
			ignoresig(SIGQUIT);
			if ((jp == NULL || jp->nprocs == 0) &&
			    ! fd0_redirected_p ()) {
				close(0);
				if (open(devnull, O_RDONLY) != 0)
					error(nullerr, devnull);
			}
		}
#else
		if (mode == FORK_BG) {
			ignoresig(SIGINT);
			ignoresig(SIGQUIT);
			if ((jp == NULL || jp->nprocs == 0) &&
			    ! fd0_redirected_p ()) {
				close(0);
				if (open(devnull, O_RDONLY) != 0)
					error(nullerr, devnull);
			}
		}
#endif
		for (i = njobs, p = jobtab ; --i >= 0 ; p++)
			if (p->used)
				freejob(p);
		if (wasroot && iflag) {
			setsignal(SIGINT);
			setsignal(SIGQUIT);
			setsignal(SIGTERM);
		}
		return pid;
	}
	if (rootshell && mode != FORK_NOJOB && mflag) {
		if (jp == NULL || jp->nprocs == 0)
			pgrp = pid;
		else
			pgrp = jp->ps[0].pid;
		setpgid(pid, pgrp);
	}
	if (mode == FORK_BG)
		backgndpid = pid;               /* set $! */
	if (jp) {
		struct procstat *ps = &jp->ps[jp->nprocs++];
		ps->pid = pid;
		ps->status = -1;
		ps->cmd = nullstr;
		if (iflag && rootshell && n)
			ps->cmd = commandtext(n);
	}
	INTON;
	TRACE(("In parent shell:  child = %d\n", pid));
	return pid;
}



/*
 * Wait for job to finish.
 *
 * Under job control we have the problem that while a child process is
 * running interrupts generated by the user are sent to the child but not
 * to the shell.  This means that an infinite loop started by an inter-
 * active user may be hard to kill.  With job control turned off, an
 * interactive user may place an interactive program inside a loop.  If
 * the interactive program catches interrupts, the user doesn't want
 * these interrupts to also abort the loop.  The approach we take here
 * is to have the shell ignore interrupt signals while waiting for a
 * forground process to terminate, and then send itself an interrupt
 * signal if the child process was terminated by an interrupt signal.
 * Unfortunately, some programs want to do a bit of cleanup and then
 * exit on interrupt; unless these processes terminate themselves by
 * sending a signal to themselves (instead of calling exit) they will
 * confuse this approach.
 */

static int
waitforjob(jp)
	struct job *jp;
	{
#ifdef JOBS
	int mypgrp = getpgrp();
#endif
	int status;
	int st;
	struct sigaction act, oact;

	INTOFF;
	intreceived = 0;
#ifdef JOBS
	if (!jobctl) {
#else
	if (!iflag) {
#endif
		sigaction(SIGINT, 0, &act);
		act.sa_handler = waitonint;
		sigaction(SIGINT, &act, &oact);
	}
	TRACE(("waitforjob(%%%d) called\n", jp - jobtab + 1));
	while (jp->state == 0) {
		dowait(1, jp);
	}
#ifdef JOBS
	if (!jobctl) {
#else
	if (!iflag) {
#endif
		sigaction(SIGINT, &oact, 0);
		if (intreceived && trap[SIGINT]) kill(getpid(), SIGINT);
	}
#ifdef JOBS
	if (jp->jobctl) {
#ifdef OLD_TTY_DRIVER
		if (ioctl(fileno2, TIOCSPGRP, (char *)&mypgrp) < 0)
			error("TIOCSPGRP failed, errno=%d\n", errno);
#else
		if (tcsetpgrp(fileno2, mypgrp) < 0)
			error("tcsetpgrp failed, errno=%d\n", errno);
#endif
	}
	if (jp->state == JOBSTOPPED)
		curjob = jp - jobtab + 1;
#endif
	status = jp->ps[jp->nprocs - 1].status;
	/* convert to 8 bits */
	if (WIFEXITED(status))
		st = WEXITSTATUS(status);
#ifdef JOBS
	else if (WIFSTOPPED(status))
		st = WSTOPSIG(status) + 128;
#endif
	else
		st = WTERMSIG(status) + 128;
#ifdef JOBS
	if (jp->jobctl) {
		/*
		 * This is truly gross.
		 * If we're doing job control, then we did a TIOCSPGRP which
		 * caused us (the shell) to no longer be in the controlling
		 * session -- so we wouldn't have seen any ^C/SIGINT.  So, we
		 * intuit from the subprocess exit status whether a SIGINT
		 * occured, and if so interrupt ourselves.  Yuck.  - mycroft
		 */
		if (WIFSIGNALED(status) && WTERMSIG(status) == SIGINT)
			raise(SIGINT);
	}
	if (jp->state == JOBDONE)

#endif
		freejob(jp);
	INTON;
	return st;
}



/*
 * Wait for a process to terminate.
 */

static int
dowait(block, job)
	int block;
	struct job *job;
{
	int pid;
	int status;
	struct procstat *sp;
	struct job *jp;
	struct job *thisjob;
	int done;
	int stopped;
	int core;
	int sig;

	TRACE(("dowait(%d) called\n", block));
	do {
		pid = waitproc(block, &status);
		TRACE(("wait returns %d, status=%d\n", pid, status));
	} while (!(block & 2) && pid == -1 && errno == EINTR);
	if (pid <= 0)
		return pid;
	INTOFF;
	thisjob = NULL;
	for (jp = jobtab ; jp < jobtab + njobs ; jp++) {
		if (jp->used) {
			done = 1;
			stopped = 1;
			for (sp = jp->ps ; sp < jp->ps + jp->nprocs ; sp++) {
				if (sp->pid == -1)
					continue;
				if (sp->pid == pid) {
					TRACE(("Changing status of proc %d from 0x%x to 0x%x\n", pid, sp->status, status));
					sp->status = status;
					thisjob = jp;
				}
				if (sp->status == -1)
					stopped = 0;
				else if (WIFSTOPPED(sp->status))
					done = 0;
			}
			if (stopped) {          /* stopped or done */
				int state = done? JOBDONE : JOBSTOPPED;
				if (jp->state != state) {
					TRACE(("Job %d: changing state from %d to %d\n", jp - jobtab + 1, jp->state, state));
					jp->state = state;
#ifdef JOBS
					if (done && curjob == jp - jobtab + 1)
						curjob = 0;             /* no current job */
#endif
				}
			}
		}
	}
	INTON;
	if (! rootshell || ! iflag || (job && thisjob == job)) {
		core = WCOREDUMP(status);
#ifdef JOBS
		if (WIFSTOPPED(status)) sig = WSTOPSIG(status);
		else
#endif
		if (WIFEXITED(status)) sig = 0;
		else sig = WTERMSIG(status);

		if (sig != 0 && sig != SIGINT && sig != SIGPIPE) {
			if (thisjob != job)
				outfmt(out2, "%d: ", pid);
#ifdef JOBS
			if (sig == SIGTSTP && rootshell && iflag)
				outfmt(out2, "%%%ld ",
				    (long)(job - jobtab + 1));
#endif
			if (sig < NSIG && sys_siglist[sig])
				out2str(sys_siglist[sig]);
			else
				outfmt(out2, "Signal %d", sig);
			if (core)
				out2str(" - core dumped");
			out2c('\n');
#ifdef FLUSHERR
			flushout(&errout);
#endif
		} else {
			TRACE(("Not printing status: status=%d, sig=%d\n",
			       status, sig));
		}
	} else {
		TRACE(("Not printing status, rootshell=%d, job=0x%x\n", rootshell, job));
		if (thisjob)
			thisjob->changed = 1;
	}
	return pid;
}



/*
 * Do a wait system call.  If job control is compiled in, we accept
 * stopped processes.  If block is zero, we return a value of zero
 * rather than blocking.
 *
 * System V doesn't have a non-blocking wait system call.  It does
 * have a SIGCLD signal that is sent to a process when one of it's
 * children dies.  The obvious way to use SIGCLD would be to install
 * a handler for SIGCLD which simply bumped a counter when a SIGCLD
 * was received, and have waitproc bump another counter when it got
 * the status of a process.  Waitproc would then know that a wait
 * system call would not block if the two counters were different.
 * This approach doesn't work because if a process has children that
 * have not been waited for, System V will send it a SIGCLD when it
 * installs a signal handler for SIGCLD.  What this means is that when
 * a child exits, the shell will be sent SIGCLD signals continuously
 * until is runs out of stack space, unless it does a wait call before
 * restoring the signal handler.  The code below takes advantage of
 * this (mis)feature by installing a signal handler for SIGCLD and
 * then checking to see whether it was called.  If there are any
 * children to be waited for, it will be.
 *
 */

static int
waitproc(block, status)
	int block;
	int *status;
{
	int flags;

	flags = 0;
#ifdef JOBS
	if (jobctl)
		flags |= WUNTRACED;
#endif
	if (block == 0)
		flags |= WNOHANG;
	return wait3(status, flags, (struct rusage *)NULL);
}

/*
 * return 1 if there are stopped jobs, otherwise 0
 */
static int
stoppedjobs(void)
{
	int jobno;
	struct job *jp;

	if (job_warning)
		return (0);
	for (jobno = 1, jp = jobtab; jobno <= njobs; jobno++, jp++) {
		if (jp->used == 0)
			continue;
		if (jp->state == JOBSTOPPED) {
			out2str("You have stopped jobs.\n");
			job_warning = 2;
			return (1);
		}
	}

	return (0);
}

/*
 * Return a string identifying a command (to be printed by the
 * jobs command.
 */

static char *cmdnextc;
static int cmdnleft;
#define MAXCMDTEXT      200

static void
cmdputs(const char *s)
{
	const char *p;
	char *q;
	char c;
	int subtype = 0;

	if (cmdnleft <= 0)
		return;
	p = s;
	q = cmdnextc;
	while ((c = *p++) != '\0') {
		if (c == CTLESC)
			*q++ = *p++;
		else if (c == CTLVAR) {
			*q++ = '$';
			if (--cmdnleft > 0)
				*q++ = '{';
			subtype = *p++;
		} else if (c == '=' && subtype != 0) {
			*q++ = "}-+?="[(subtype & VSTYPE) - VSNORMAL];
			subtype = 0;
		} else if (c == CTLENDVAR) {
			*q++ = '}';
		} else if (c == CTLBACKQ || c == CTLBACKQ+CTLQUOTE)
			cmdnleft++;             /* ignore it */
		else
			*q++ = c;
		if (--cmdnleft <= 0) {
			*q++ = '.';
			*q++ = '.';
			*q++ = '.';
			break;
		}
	}
	cmdnextc = q;
}


static void
cmdtxt(const union node *n)
{
	union node *np;
	struct nodelist *lp;
	const char *p;
	int i;
	char s[2];

	if (n == NULL)
		return;
	switch (n->type) {
	case NSEMI:
		cmdtxt(n->nbinary.ch1);
		cmdputs("; ");
		cmdtxt(n->nbinary.ch2);
		break;
	case NAND:
		cmdtxt(n->nbinary.ch1);
		cmdputs(" && ");
		cmdtxt(n->nbinary.ch2);
		break;
	case NOR:
		cmdtxt(n->nbinary.ch1);
		cmdputs(" || ");
		cmdtxt(n->nbinary.ch2);
		break;
	case NPIPE:
		for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
			cmdtxt(lp->n);
			if (lp->next)
				cmdputs(" | ");
		}
		break;
	case NSUBSHELL:
		cmdputs("(");
		cmdtxt(n->nredir.n);
		cmdputs(")");
		break;
	case NREDIR:
	case NBACKGND:
		cmdtxt(n->nredir.n);
		break;
	case NIF:
		cmdputs("if ");
		cmdtxt(n->nif.test);
		cmdputs("; then ");
		cmdtxt(n->nif.ifpart);
		cmdputs("...");
		break;
	case NWHILE:
		cmdputs("while ");
		goto until;
	case NUNTIL:
		cmdputs("until ");
until:
		cmdtxt(n->nbinary.ch1);
		cmdputs("; do ");
		cmdtxt(n->nbinary.ch2);
		cmdputs("; done");
		break;
	case NFOR:
		cmdputs("for ");
		cmdputs(n->nfor.var);
		cmdputs(" in ...");
		break;
	case NCASE:
		cmdputs("case ");
		cmdputs(n->ncase.expr->narg.text);
		cmdputs(" in ...");
		break;
	case NDEFUN:
		cmdputs(n->narg.text);
		cmdputs("() ...");
		break;
	case NCMD:
		for (np = n->ncmd.args ; np ; np = np->narg.next) {
			cmdtxt(np);
			if (np->narg.next)
				cmdputs(spcstr);
		}
		for (np = n->ncmd.redirect ; np ; np = np->nfile.next) {
			cmdputs(spcstr);
			cmdtxt(np);
		}
		break;
	case NARG:
		cmdputs(n->narg.text);
		break;
	case NTO:
		p = ">";  i = 1;  goto redir;
	case NAPPEND:
		p = ">>";  i = 1;  goto redir;
	case NTOFD:
		p = ">&";  i = 1;  goto redir;
	case NTOOV:
		p = ">|";  i = 1;  goto redir;
	case NFROM:
		p = "<";  i = 0;  goto redir;
	case NFROMFD:
		p = "<&";  i = 0;  goto redir;
	case NFROMTO:
		p = "<>";  i = 0;  goto redir;
redir:
		if (n->nfile.fd != i) {
			s[0] = n->nfile.fd + '0';
			s[1] = '\0';
			cmdputs(s);
		}
		cmdputs(p);
		if (n->type == NTOFD || n->type == NFROMFD) {
			s[0] = n->ndup.dupfd + '0';
			s[1] = '\0';
			cmdputs(s);
		} else {
			cmdtxt(n->nfile.fname);
		}
		break;
	case NHERE:
	case NXHERE:
		cmdputs("<<...");
		break;
	default:
		cmdputs("???");
		break;
	}
}


static char *
commandtext(const union node *n)
{
	char *name;

	cmdnextc = name = ckmalloc(MAXCMDTEXT);
	cmdnleft = MAXCMDTEXT - 4;
	cmdtxt(n);
	*cmdnextc = '\0';
	return name;
}


static void waitonint(int sig) {
	intreceived = 1;
	return;
}
/*
 * Routines to check for mail.  (Perhaps make part of main.c?)
 */


#define MAXMBOXES 10


static int nmboxes;                     /* number of mailboxes */
static time_t mailtime[MAXMBOXES];      /* times of mailboxes */



/*
 * Print appropriate message(s) if mail has arrived.  If the argument is
 * nozero, then the value of MAIL has changed, so we just update the
 * values.
 */

static void
chkmail(int silent)
{
	int i;
	const char *mpath;
	char *p;
	char *q;
	struct stackmark smark;
	struct stat statb;

	if (silent)
		nmboxes = 10;
	if (nmboxes == 0)
		return;
	setstackmark(&smark);
	mpath = mpathset()? mpathval() : mailval();
	for (i = 0 ; i < nmboxes ; i++) {
		p = padvance(&mpath, nullstr);
		if (p == NULL)
			break;
		if (*p == '\0')
			continue;
		for (q = p ; *q ; q++);
#ifdef DEBUG
		if (q[-1] != '/')
			abort();
#endif
		q[-1] = '\0';                   /* delete trailing '/' */
		if (stat(p, &statb) < 0)
			statb.st_size = 0;
		if (statb.st_size > mailtime[i] && ! silent) {
			outfmt(
				&errout, snlfmt,
				pathopt? pathopt : "you have mail"
			);
		}
		mailtime[i] = statb.st_size;
	}
	nmboxes = i;
	popstackmark(&smark);
}

#define PROFILE 0

#if PROFILE
static short profile_buf[16384];
extern int etext();
#endif

static void read_profile (const char *);
static char *find_dot_file (char *);
static void cmdloop (int);
static void options (int);
static void minus_o (char *, int);
static void setoption (int, int);
static void procargs (int, char **);


/*
 * Main routine.  We initialize things, parse the arguments, execute
 * profiles if we're a login shell, and then call cmdloop to execute
 * commands.  The setjmp call sets up the location to jump to when an
 * exception occurs.  When an exception occurs the variable "state"
 * is used to figure out how far we had gotten.
 */

int
shell_main(argc, argv)
	int argc;
	char **argv;
{
	struct jmploc jmploc;
	struct stackmark smark;
	volatile int state;
	char *shinit;

	DOTCMD = find_builtin(".");
	BLTINCMD = find_builtin("builtin");
	EXECCMD = find_builtin("exec");
	EVALCMD = find_builtin("eval");

#if PROFILE
	monitor(4, etext, profile_buf, sizeof profile_buf, 50);
#endif
#if defined(linux) || defined(__GNU__)
	signal(SIGCHLD, SIG_DFL);
#endif
	state = 0;
	if (setjmp(jmploc.loc)) {
		INTOFF;
		/*
		 * When a shell procedure is executed, we raise the
		 * exception EXSHELLPROC to clean up before executing
		 * the shell procedure.
		 */
		switch (exception) {
		case EXSHELLPROC:
			rootpid = getpid();
			rootshell = 1;
			minusc = NULL;
			state = 3;
			break;

		case EXEXEC:
			exitstatus = exerrno;
			break;

		case EXERROR:
			exitstatus = 2;
			break;

		default:
			break;
		}

		if (exception != EXSHELLPROC) {
		    if (state == 0 || iflag == 0 || ! rootshell)
			    exitshell(exitstatus);
		}
		reset();
		if (exception == EXINT) {
			out2c('\n');
#ifdef FLUSHERR
			flushout(out2);
#endif
		}
		popstackmark(&smark);
		FORCEINTON;                             /* enable interrupts */
		if (state == 1)
			goto state1;
		else if (state == 2)
			goto state2;
		else if (state == 3)
			goto state3;
		else
			goto state4;
	}
	handler = &jmploc;
#ifdef DEBUG
	opentrace();
	trputs("Shell args:  ");  trargs(argv);
#endif
	rootpid = getpid();
	rootshell = 1;
	init();
	setstackmark(&smark);
	procargs(argc, argv);
	if (argv[0] && argv[0][0] == '-') {
		state = 1;
		read_profile("/etc/profile");
state1:
		state = 2;
		read_profile(".profile");
	}
state2:
	state = 3;
#ifndef linux
	if (getuid() == geteuid() && getgid() == getegid()) {
#endif
		if ((shinit = lookupvar("ENV")) != NULL && *shinit != '\0') {
			state = 3;
			read_profile(shinit);
		}
#ifndef linux
	}
#endif
state3:
	state = 4;
	if (sflag == 0 || minusc) {
		static int sigs[] =  {
		    SIGINT, SIGQUIT, SIGHUP,
#ifdef SIGTSTP
		    SIGTSTP,
#endif
		    SIGPIPE
		};
#define SIGSSIZE (sizeof(sigs)/sizeof(sigs[0]))
		int i;

		for (i = 0; i < SIGSSIZE; i++)
		    setsignal(sigs[i]);
	}

	if (minusc)
		evalstring(minusc, 0);

	if (sflag || minusc == NULL) {
state4: /* XXX ??? - why isn't this before the "if" statement */
		cmdloop(1);
	}
#if PROFILE
	monitor(0);
#endif
	exitshell(exitstatus);
	/* NOTREACHED */
}


/*
 * Read and execute commands.  "Top" is nonzero for the top level command
 * loop; it turns on prompting if the shell is interactive.
 */

static void
cmdloop(int top)
{
	union node *n;
	struct stackmark smark;
	int inter;
	int numeof = 0;

	TRACE(("cmdloop(%d) called\n", top));
	setstackmark(&smark);
	for (;;) {
		if (pendingsigs)
			dotrap();
		inter = 0;
		if (iflag && top) {
			inter++;
			showjobs(1);
			chkmail(0);
			flushout(&output);
		}
		n = parsecmd(inter);
		/* showtree(n); DEBUG */
		if (n == NEOF) {
			if (!top || numeof >= 50)
				break;
			if (!stoppedjobs()) {
				if (!Iflag)
					break;
				out2str("\nUse \"exit\" to leave shell.\n");
			}
			numeof++;
		} else if (n != NULL && nflag == 0) {
			job_warning = (job_warning == 2) ? 1 : 0;
			numeof = 0;
			evaltree(n, 0);
		}
		popstackmark(&smark);
		setstackmark(&smark);
		if (evalskip == SKIPFILE) {
			evalskip = 0;
			break;
		}
	}
	popstackmark(&smark);
}



/*
 * Read /etc/profile or .profile.  Return on error.
 */

static void
read_profile(name)
	const char *name;
{
	int fd;
	int xflag_set = 0;
	int vflag_set = 0;

	INTOFF;
	if ((fd = open(name, O_RDONLY)) >= 0)
		setinputfd(fd, 1);
	INTON;
	if (fd < 0)
		return;
	/* -q turns off -x and -v just when executing init files */
	if (qflag)  {
	    if (xflag)
		    xflag = 0, xflag_set = 1;
	    if (vflag)
		    vflag = 0, vflag_set = 1;
	}
	cmdloop(0);
	if (qflag)  {
	    if (xflag_set)
		    xflag = 1;
	    if (vflag_set)
		    vflag = 1;
	}
	popfile();
}



/*
 * Read a file containing shell functions.
 */

static void
readcmdfile(const char *name)
{
	int fd;

	INTOFF;
	if ((fd = open(name, O_RDONLY)) >= 0)
		setinputfd(fd, 1);
	else
		error("Can't open %s", name);
	INTON;
	cmdloop(0);
	popfile();
}



/*
 * Take commands from a file.  To be compatable we should do a path
 * search for the file, which is necessary to find sub-commands.
 */


static char *
find_dot_file(mybasename)
	char *mybasename;
{
	char *fullname;
	const char *path = pathval();
	struct stat statb;

	/* don't try this for absolute or relative paths */
	if (strchr(mybasename, '/'))
		return mybasename;

	while ((fullname = padvance(&path, mybasename)) != NULL) {
		if ((stat(fullname, &statb) == 0) && S_ISREG(statb.st_mode)) {
			/*
			 * Don't bother freeing here, since it will
			 * be freed by the caller.
			 */
			return fullname;
		}
		stunalloc(fullname);
	}

	/* not found in the PATH */
	error("%s: not found", mybasename);
	/* NOTREACHED */
}

static int
dotcmd(argc, argv)
	int argc;
	char **argv;
{
	struct strlist *sp;
	exitstatus = 0;

	for (sp = cmdenviron; sp ; sp = sp->next)
		setvareq(savestr(sp->text), VSTRFIXED|VTEXTFIXED);

	if (argc >= 2) {                /* That's what SVR2 does */
		char *fullname;
		struct stackmark smark;

		setstackmark(&smark);
		fullname = find_dot_file(argv[1]);
		setinputfile(fullname, 1);
		commandname = fullname;
		cmdloop(0);
		popfile();
		popstackmark(&smark);
	}
	return exitstatus;
}


static int
exitcmd(argc, argv)
	int argc;
	char **argv;
{
	if (stoppedjobs())
		return 0;
	if (argc > 1)
		exitstatus = number(argv[1]);
	else
		exitstatus = oexitstatus;
	exitshell(exitstatus);
	/* NOTREACHED */
}
static pointer
stalloc(int nbytes)
{
	char *p;

	nbytes = ALIGN(nbytes);
	if (nbytes > stacknleft) {
		int blocksize;
		struct stack_block *sp;

		blocksize = nbytes;
		if (blocksize < MINSIZE)
			blocksize = MINSIZE;
		INTOFF;
		sp = ckmalloc(sizeof(struct stack_block) - MINSIZE + blocksize);
		sp->prev = stackp;
		stacknxt = sp->space;
		stacknleft = blocksize;
		stackp = sp;
		INTON;
	}
	p = stacknxt;
	stacknxt += nbytes;
	stacknleft -= nbytes;
	return p;
}


static void
stunalloc(pointer p)
{
#ifdef DEBUG
	if (p == NULL) {                /*DEBUG */
		write(2, "stunalloc\n", 10);
		abort();
	}
#endif
	if (!(stacknxt >= (char *)p && (char *)p >= stackp->space)) {
		p = stackp->space;
	}
	stacknleft += stacknxt - (char *)p;
	stacknxt = p;
}


static void
setstackmark(struct stackmark *mark)
{
	mark->stackp = stackp;
	mark->stacknxt = stacknxt;
	mark->stacknleft = stacknleft;
	mark->marknext = markp;
	markp = mark;
}


static void
popstackmark(struct stackmark *mark)
{
	struct stack_block *sp;

	INTOFF;
	markp = mark->marknext;
	while (stackp != mark->stackp) {
		sp = stackp;
		stackp = sp->prev;
		ckfree(sp);
	}
	stacknxt = mark->stacknxt;
	stacknleft = mark->stacknleft;
	INTON;
}


/*
 * When the parser reads in a string, it wants to stick the string on the
 * stack and only adjust the stack pointer when it knows how big the
 * string is.  Stackblock (defined in stack.h) returns a pointer to a block
 * of space on top of the stack and stackblocklen returns the length of
 * this block.  Growstackblock will grow this space by at least one byte,
 * possibly moving it (like realloc).  Grabstackblock actually allocates the
 * part of the block that has been used.
 */

static void
growstackblock(void) {
	char *p;
	int newlen = ALIGN(stacknleft * 2 + 100);
	char *oldspace = stacknxt;
	int oldlen = stacknleft;
	struct stack_block *sp;
	struct stack_block *oldstackp;

	if (stacknxt == stackp->space && stackp != &stackbase) {
		INTOFF;
		oldstackp = stackp;
		sp = stackp;
		stackp = sp->prev;
		sp = ckrealloc((pointer)sp, sizeof(struct stack_block) - MINSIZE + newlen);
		sp->prev = stackp;
		stackp = sp;
		stacknxt = sp->space;
		stacknleft = newlen;
		{
		  /* Stack marks pointing to the start of the old block
		   * must be relocated to point to the new block
		   */
		  struct stackmark *xmark;
		  xmark = markp;
		  while (xmark != NULL && xmark->stackp == oldstackp) {
		    xmark->stackp = stackp;
		    xmark->stacknxt = stacknxt;
		    xmark->stacknleft = stacknleft;
		    xmark = xmark->marknext;
		  }
		}
		INTON;
	} else {
		p = stalloc(newlen);
		memcpy(p, oldspace, oldlen);
		stacknxt = p;                   /* free the space */
		stacknleft += newlen;           /* we just allocated */
	}
}



static inline void
grabstackblock(int len)
{
	len = ALIGN(len);
	stacknxt += len;
	stacknleft -= len;
}



/*
 * The following routines are somewhat easier to use that the above.
 * The user declares a variable of type STACKSTR, which may be declared
 * to be a register.  The macro STARTSTACKSTR initializes things.  Then
 * the user uses the macro STPUTC to add characters to the string.  In
 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
 * grown as necessary.  When the user is done, she can just leave the
 * string there and refer to it using stackblock().  Or she can allocate
 * the space for it using grabstackstr().  If it is necessary to allow
 * someone else to use the stack temporarily and then continue to grow
 * the string, the user should use grabstack to allocate the space, and
 * then call ungrabstr(p) to return to the previous mode of operation.
 *
 * USTPUTC is like STPUTC except that it doesn't check for overflow.
 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
 * is space for at least one character.
 */


static char *
growstackstr(void) {
	int len = stackblocksize();
	if (herefd >= 0 && len >= 1024) {
		xwrite(herefd, stackblock(), len);
		sstrnleft = len - 1;
		return stackblock();
	}
	growstackblock();
	sstrnleft = stackblocksize() - len - 1;
	return stackblock() + len;
}


/*
 * Called from CHECKSTRSPACE.
 */

static char *
makestrspace(size_t newlen) {
	int len = stackblocksize() - sstrnleft;
	do {
		growstackblock();
		sstrnleft = stackblocksize() - len;
	} while (sstrnleft < newlen);
	return stackblock() + len;
}



static void
ungrabstackstr(char *s, char *p)
{
	stacknleft += stacknxt - s;
	stacknxt = s;
	sstrnleft = stacknleft - (p - s);
}
/*
 * Miscelaneous builtins.
 */


#undef rflag

#ifdef __GLIBC__
static mode_t getmode(const void *, mode_t);
static void *setmode(const char *);

#if !defined(__GLIBC__) || __GLIBC__ == 2 && __GLIBC_MINOR__ < 1
typedef enum __rlimit_resource rlim_t;
#endif
#endif



/*
 * The read builtin.  The -e option causes backslashes to escape the
 * following character.
 *
 * This uses unbuffered input, which may be avoidable in some cases.
 */

static int
readcmd(argc, argv)
	int argc;
	char **argv;
{
	char **ap;
	int backslash;
	char c;
	int rflag;
	char *prompt;
	const char *ifs;
	char *p;
	int startword;
	int status;
	int i;

	rflag = 0;
	prompt = NULL;
	while ((i = nextopt("p:r")) != '\0') {
		if (i == 'p')
			prompt = optionarg;
		else
			rflag = 1;
	}
	if (prompt && isatty(0)) {
		putprompt(prompt);
		flushall();
	}
	if (*(ap = argptr) == NULL)
		error("arg count");
	if ((ifs = bltinlookup("IFS")) == NULL)
		ifs = defifs;
	status = 0;
	startword = 1;
	backslash = 0;
	STARTSTACKSTR(p);
	for (;;) {
		if (read(0, &c, 1) != 1) {
			status = 1;
			break;
		}
		if (c == '\0')
			continue;
		if (backslash) {
			backslash = 0;
			if (c != '\n')
				STPUTC(c, p);
			continue;
		}
		if (!rflag && c == '\\') {
			backslash++;
			continue;
		}
		if (c == '\n')
			break;
		if (startword && *ifs == ' ' && strchr(ifs, c)) {
			continue;
		}
		startword = 0;
		if (backslash && c == '\\') {
			if (read(0, &c, 1) != 1) {
				status = 1;
				break;
			}
			STPUTC(c, p);
		} else if (ap[1] != NULL && strchr(ifs, c) != NULL) {
			STACKSTRNUL(p);
			setvar(*ap, stackblock(), 0);
			ap++;
			startword = 1;
			STARTSTACKSTR(p);
		} else {
			STPUTC(c, p);
		}
	}
	STACKSTRNUL(p);
	/* Remove trailing blanks */
	while (stackblock() <= --p && strchr(ifs, *p) != NULL)
		*p = '\0';
	setvar(*ap, stackblock(), 0);
	while (*++ap != NULL)
		setvar(*ap, nullstr, 0);
	return status;
}



static int
umaskcmd(argc, argv)
	int argc;
	char **argv;
{
	char *ap;
	int mask;
	int i;
	int symbolic_mode = 0;

	while ((i = nextopt("S")) != '\0') {
		symbolic_mode = 1;
	}

	INTOFF;
	mask = umask(0);
	umask(mask);
	INTON;

	if ((ap = *argptr) == NULL) {
		if (symbolic_mode) {
			char u[4], g[4], o[4];

			i = 0;
			if ((mask & S_IRUSR) == 0)
				u[i++] = 'r';
			if ((mask & S_IWUSR) == 0)
				u[i++] = 'w';
			if ((mask & S_IXUSR) == 0)
				u[i++] = 'x';
			u[i] = '\0';

			i = 0;
			if ((mask & S_IRGRP) == 0)
				g[i++] = 'r';
			if ((mask & S_IWGRP) == 0)
				g[i++] = 'w';
			if ((mask & S_IXGRP) == 0)
				g[i++] = 'x';
			g[i] = '\0';

			i = 0;
			if ((mask & S_IROTH) == 0)
				o[i++] = 'r';
			if ((mask & S_IWOTH) == 0)
				o[i++] = 'w';
			if ((mask & S_IXOTH) == 0)
				o[i++] = 'x';
			o[i] = '\0';

			out1fmt("u=%s,g=%s,o=%s\n", u, g, o);
		} else {
			out1fmt("%.4o\n", mask);
		}
	} else {
		if (isdigit((unsigned char)*ap)) {
			mask = 0;
			do {
				if (*ap >= '8' || *ap < '0')
					error("Illegal number: %s", argv[1]);
				mask = (mask << 3) + (*ap - '0');
			} while (*++ap != '\0');
			umask(mask);
		} else {
			void *set;

			INTOFF;
			if ((set = setmode(ap)) != 0) {
				mask = getmode(set, ~mask & 0777);
				ckfree(set);
			}
			INTON;
			if (!set)
				error("Illegal mode: %s", ap);

			umask(~mask & 0777);
		}
	}
	return 0;
}

/*
 * ulimit builtin
 *
 * This code, originally by Doug Gwyn, Doug Kingston, Eric Gisin, and
 * Michael Rendell was ripped from pdksh 5.0.8 and hacked for use with
 * ash by J.T. Conklin.
 *
 * Public domain.
 */

struct limits {
	const char *name;
	int     cmd;
	int     factor; /* multiply by to get rlim_{cur,max} values */
	char    option;
};

static const struct limits limits[] = {
#ifdef RLIMIT_CPU
	{ "time(seconds)",              RLIMIT_CPU,        1, 't' },
#endif
#ifdef RLIMIT_FSIZE
	{ "file(blocks)",               RLIMIT_FSIZE,    512, 'f' },
#endif
#ifdef RLIMIT_DATA
	{ "data(kbytes)",               RLIMIT_DATA,    1024, 'd' },
#endif
#ifdef RLIMIT_STACK
	{ "stack(kbytes)",              RLIMIT_STACK,   1024, 's' },
#endif
#ifdef  RLIMIT_CORE
	{ "coredump(blocks)",           RLIMIT_CORE,     512, 'c' },
#endif
#ifdef RLIMIT_RSS
	{ "memory(kbytes)",             RLIMIT_RSS,     1024, 'm' },
#endif
#ifdef RLIMIT_MEMLOCK
	{ "locked memory(kbytes)",      RLIMIT_MEMLOCK, 1024, 'l' },
#endif
#ifdef RLIMIT_NPROC
	{ "process(processes)",         RLIMIT_NPROC,      1, 'p' },
#endif
#ifdef RLIMIT_NOFILE
	{ "nofiles(descriptors)",       RLIMIT_NOFILE,     1, 'n' },
#endif
#ifdef RLIMIT_VMEM
	{ "vmemory(kbytes)",            RLIMIT_VMEM,    1024, 'v' },
#endif
#ifdef RLIMIT_SWAP
	{ "swap(kbytes)",               RLIMIT_SWAP,    1024, 'w' },
#endif
	{ (char *) 0,                   0,                 0,  '\0' }
};

static int
ulimitcmd(argc, argv)
	int argc;
	char **argv;
{
	int     c;
	rlim_t val = 0;
	enum { SOFT = 0x1, HARD = 0x2 }
			how = SOFT | HARD;
	const struct limits     *l;
	int             set, all = 0;
	int             optc, what;
	struct rlimit   limit;

	what = 'f';
	while ((optc = nextopt("HSatfdsmcnpl")) != '\0')
		switch (optc) {
		case 'H':
			how = HARD;
			break;
		case 'S':
			how = SOFT;
			break;
		case 'a':
			all = 1;
			break;
		default:
			what = optc;
		}

	for (l = limits; l->name && l->option != what; l++)
		;
	if (!l->name)
		error("internal error (%c)", what);

	set = *argptr ? 1 : 0;
	if (set) {
		char *p = *argptr;

		if (all || argptr[1])
			error("too many arguments");
		if (strcmp(p, "unlimited") == 0)
			val = RLIM_INFINITY;
		else {
			val = (rlim_t) 0;

			while ((c = *p++) >= '0' && c <= '9')
			{
				val = (val * 10) + (long)(c - '0');
				if (val < (rlim_t) 0)
					break;
			}
			if (c)
				error("bad number");
			val *= l->factor;
		}
	}
	if (all) {
		for (l = limits; l->name; l++) {
			getrlimit(l->cmd, &limit);
			if (how & SOFT)
				val = limit.rlim_cur;
			else if (how & HARD)
				val = limit.rlim_max;

			out1fmt("%-20s ", l->name);
			if (val == RLIM_INFINITY)
				out1fmt("unlimited\n");
			else
			{
				val /= l->factor;
				out1fmt("%lld\n", (long long) val);
			}
		}
		return 0;
	}

	getrlimit(l->cmd, &limit);
	if (set) {
		if (how & HARD)
			limit.rlim_max = val;
		if (how & SOFT)
			limit.rlim_cur = val;
		if (setrlimit(l->cmd, &limit) < 0)
			error("error setting limit (%m)");
	} else {
		if (how & SOFT)
			val = limit.rlim_cur;
		else if (how & HARD)
			val = limit.rlim_max;

		if (val == RLIM_INFINITY)
			out1fmt("unlimited\n");
		else
		{
			val /= l->factor;
			out1fmt("%lld\n", (long long) val);
		}
	}
	return 0;
}
/*
 * prefix -- see if pfx is a prefix of string.
 */

static int
prefix(pfx, string)
	char const *pfx;
	char const *string;
	{
	while (*pfx) {
		if (*pfx++ != *string++)
			return 0;
	}
	return 1;
}

/*
 * Return true if s is a string of digits, and save munber in intptr
 * nagative is bad
 */

static int
is_number(const char *p, int *intptr)
{
	int ret = 0;

	do {
		if (! is_digit(*p))
			return 0;
		ret *= 10;
		ret += digit_val(*p);
		p++;
	} while (*p != '\0');

	*intptr = ret;
	return 1;
}

/*
 * Convert a string of digits to an integer, printing an error message on
 * failure.
 */

static int
number(const char *s)
{
	int i;
	if (! is_number(s, &i))
		error("Illegal number: %s", s);
	return i;
}

/*
 * Produce a possibly single quoted string suitable as input to the shell.
 * The return string is allocated on the stack.
 */

static char *
single_quote(const char *s) {
	char *p;

	STARTSTACKSTR(p);

	do {
		char *q = p;
		size_t len1, len1p, len2, len2p;

		len1 = strcspn(s, "'");
		len2 = strspn(s + len1, "'");

		len1p = len1 ? len1 + 2 : len1;
		switch (len2) {
		case 0:
			len2p = 0;
			break;
		case 1:
			len2p = 2;
			break;
		default:
			len2p = len2 + 2;
		}

		CHECKSTRSPACE(len1p + len2p + 1, p);

		if (len1) {
			*p = '\'';
#ifdef _GNU_SOURCE
			q = mempcpy(p + 1, s, len1);
#else
			q = p + 1 + len1;
			memcpy(p + 1, s, len1);
#endif
			*q++ = '\'';
			s += len1;
		}

		switch (len2) {
		case 0:
			break;
		case 1:
			*q++ = '\\';
			*q = '\'';
			s++;
			break;
		default:
			*q = '"';
#ifdef _GNU_SOURCE
			*(char *) mempcpy(q + 1, s, len2) = '"';
#else
			q += 1 + len2;
			memcpy(q + 1, s, len2);
			*q = '"';
#endif
			s += len2;
		}

		STADJUST(len1p + len2p, p);
	} while (*s);

	USTPUTC(0, p);

	return grabstackstr(p);
}

/*
 * Like strdup but works with the ash stack.
 */

static char *
sstrdup(const char *p)
{
	size_t len = strlen(p) + 1;
	return memcpy(stalloc(len), p, len);
}


/*
 * This file was generated by the mknodes program.
 */

/*
 * Routine for dealing with parsed shell commands.
 */


static int     funcblocksize;           /* size of structures in function */
static int     funcstringsize;          /* size of strings in node */
static pointer funcblock;              /* block to allocate function from */
static char   *funcstring;              /* block to allocate strings from */

static const short nodesize[26] = {
      ALIGN(sizeof (struct nbinary)),
      ALIGN(sizeof (struct ncmd)),
      ALIGN(sizeof (struct npipe)),
      ALIGN(sizeof (struct nredir)),
      ALIGN(sizeof (struct nredir)),
      ALIGN(sizeof (struct nredir)),
      ALIGN(sizeof (struct nbinary)),
      ALIGN(sizeof (struct nbinary)),
      ALIGN(sizeof (struct nif)),
      ALIGN(sizeof (struct nbinary)),
      ALIGN(sizeof (struct nbinary)),
      ALIGN(sizeof (struct nfor)),
      ALIGN(sizeof (struct ncase)),
      ALIGN(sizeof (struct nclist)),
      ALIGN(sizeof (struct narg)),
      ALIGN(sizeof (struct narg)),
      ALIGN(sizeof (struct nfile)),
      ALIGN(sizeof (struct nfile)),
      ALIGN(sizeof (struct nfile)),
      ALIGN(sizeof (struct nfile)),
      ALIGN(sizeof (struct nfile)),
      ALIGN(sizeof (struct ndup)),
      ALIGN(sizeof (struct ndup)),
      ALIGN(sizeof (struct nhere)),
      ALIGN(sizeof (struct nhere)),
      ALIGN(sizeof (struct nnot)),
};


static void calcsize (union node *);
static void sizenodelist (struct nodelist *);
static union node *copynode (union node *);
static struct nodelist *copynodelist (struct nodelist *);
static char *nodesavestr (char *);



/*
 * Make a copy of a parse tree.
 */

static union node *
copyfunc(union node *n)
{
	if (n == NULL)
		return NULL;
	funcblocksize = 0;
	funcstringsize = 0;
	calcsize(n);
	funcblock = ckmalloc(funcblocksize + funcstringsize);
	funcstring = (char *) funcblock + funcblocksize;
	return copynode(n);
}



static void
calcsize(n)
	union node *n;
{
      if (n == NULL)
	    return;
      funcblocksize += nodesize[n->type];
      switch (n->type) {
      case NSEMI:
      case NAND:
      case NOR:
      case NWHILE:
      case NUNTIL:
	    calcsize(n->nbinary.ch2);
	    calcsize(n->nbinary.ch1);
	    break;
      case NCMD:
	    calcsize(n->ncmd.redirect);
	    calcsize(n->ncmd.args);
	    calcsize(n->ncmd.assign);
	    break;
      case NPIPE:
	    sizenodelist(n->npipe.cmdlist);
	    break;
      case NREDIR:
      case NBACKGND:
      case NSUBSHELL:
	    calcsize(n->nredir.redirect);
	    calcsize(n->nredir.n);
	    break;
      case NIF:
	    calcsize(n->nif.elsepart);
	    calcsize(n->nif.ifpart);
	    calcsize(n->nif.test);
	    break;
      case NFOR:
	    funcstringsize += strlen(n->nfor.var) + 1;
	    calcsize(n->nfor.body);
	    calcsize(n->nfor.args);
	    break;
      case NCASE:
	    calcsize(n->ncase.cases);
	    calcsize(n->ncase.expr);
	    break;
      case NCLIST:
	    calcsize(n->nclist.body);
	    calcsize(n->nclist.pattern);
	    calcsize(n->nclist.next);
	    break;
      case NDEFUN:
      case NARG:
	    sizenodelist(n->narg.backquote);
	    funcstringsize += strlen(n->narg.text) + 1;
	    calcsize(n->narg.next);
	    break;
      case NTO:
      case NFROM:
      case NFROMTO:
      case NAPPEND:
      case NTOOV:
	    calcsize(n->nfile.fname);
	    calcsize(n->nfile.next);
	    break;
      case NTOFD:
      case NFROMFD:
	    calcsize(n->ndup.vname);
	    calcsize(n->ndup.next);
	    break;
      case NHERE:
      case NXHERE:
	    calcsize(n->nhere.doc);
	    calcsize(n->nhere.next);
	    break;
      case NNOT:
	    calcsize(n->nnot.com);
	    break;
      };
}



static void
sizenodelist(lp)
	struct nodelist *lp;
{
	while (lp) {
		funcblocksize += ALIGN(sizeof(struct nodelist));
		calcsize(lp->n);
		lp = lp->next;
	}
}



static union node *
copynode(n)
	union node *n;
{
	union node *new;

      if (n == NULL)
	    return NULL;
      new = funcblock;
      funcblock = (char *) funcblock + nodesize[n->type];
      switch (n->type) {
      case NSEMI:
      case NAND:
      case NOR:
      case NWHILE:
      case NUNTIL:
	    new->nbinary.ch2 = copynode(n->nbinary.ch2);
	    new->nbinary.ch1 = copynode(n->nbinary.ch1);
	    break;
      case NCMD:
	    new->ncmd.redirect = copynode(n->ncmd.redirect);
	    new->ncmd.args = copynode(n->ncmd.args);
	    new->ncmd.assign = copynode(n->ncmd.assign);
	    new->ncmd.backgnd = n->ncmd.backgnd;
	    break;
      case NPIPE:
	    new->npipe.cmdlist = copynodelist(n->npipe.cmdlist);
	    new->npipe.backgnd = n->npipe.backgnd;
	    break;
      case NREDIR:
      case NBACKGND:
      case NSUBSHELL:
	    new->nredir.redirect = copynode(n->nredir.redirect);
	    new->nredir.n = copynode(n->nredir.n);
	    break;
      case NIF:
	    new->nif.elsepart = copynode(n->nif.elsepart);
	    new->nif.ifpart = copynode(n->nif.ifpart);
	    new->nif.test = copynode(n->nif.test);
	    break;
      case NFOR:
	    new->nfor.var = nodesavestr(n->nfor.var);
	    new->nfor.body = copynode(n->nfor.body);
	    new->nfor.args = copynode(n->nfor.args);
	    break;
      case NCASE:
	    new->ncase.cases = copynode(n->ncase.cases);
	    new->ncase.expr = copynode(n->ncase.expr);
	    break;
      case NCLIST:
	    new->nclist.body = copynode(n->nclist.body);
	    new->nclist.pattern = copynode(n->nclist.pattern);
	    new->nclist.next = copynode(n->nclist.next);
	    break;
      case NDEFUN:
      case NARG:
	    new->narg.backquote = copynodelist(n->narg.backquote);
	    new->narg.text = nodesavestr(n->narg.text);
	    new->narg.next = copynode(n->narg.next);
	    break;
      case NTO:
      case NFROM:
      case NFROMTO:
      case NAPPEND:
      case NTOOV:
	    new->nfile.fname = copynode(n->nfile.fname);
	    new->nfile.fd = n->nfile.fd;
	    new->nfile.next = copynode(n->nfile.next);
	    break;
      case NTOFD:
      case NFROMFD:
	    new->ndup.vname = copynode(n->ndup.vname);
	    new->ndup.dupfd = n->ndup.dupfd;
	    new->ndup.fd = n->ndup.fd;
	    new->ndup.next = copynode(n->ndup.next);
	    break;
      case NHERE:
      case NXHERE:
	    new->nhere.doc = copynode(n->nhere.doc);
	    new->nhere.fd = n->nhere.fd;
	    new->nhere.next = copynode(n->nhere.next);
	    break;
      case NNOT:
	    new->nnot.com = copynode(n->nnot.com);
	    break;
      };
      new->type = n->type;
	return new;
}


static struct nodelist *
copynodelist(lp)
	struct nodelist *lp;
{
	struct nodelist *start;
	struct nodelist **lpp;

	lpp = &start;
	while (lp) {
		*lpp = funcblock;
		funcblock = (char *) funcblock + ALIGN(sizeof(struct nodelist));
		(*lpp)->n = copynode(lp->n);
		lp = lp->next;
		lpp = &(*lpp)->next;
	}
	*lpp = NULL;
	return start;
}



static char *
nodesavestr(s)
	char   *s;
{
#ifdef _GNU_SOURCE
	char   *rtn = funcstring;

	funcstring = stpcpy(funcstring, s) + 1;
	return rtn;
#else
	register char *p = s;
	register char *q = funcstring;
	char   *rtn = funcstring;

	while ((*q++ = *p++) != '\0')
		continue;
	funcstring = q;
	return rtn;
#endif
}

#ifdef ASH_GETOPTS
static int getopts (char *, char *, char **, int *, int *);
#endif


/*
 * Process the shell command line arguments.
 */

static void
procargs(argc, argv)
	int argc;
	char **argv;
{
	int i;

	argptr = argv;
	if (argc > 0)
		argptr++;
	for (i = 0; i < NOPTS; i++)
		optent_val(i) = 2;
	options(1);
	if (*argptr == NULL && minusc == NULL)
		sflag = 1;
	if (iflag == 2 && sflag == 1 && isatty(0) && isatty(1))
		iflag = 1;
	if (mflag == 2)
		mflag = iflag;
	for (i = 0; i < NOPTS; i++)
		if (optent_val(i) == 2)
			optent_val(i) = 0;
	arg0 = argv[0];
	if (sflag == 0 && minusc == NULL) {
		commandname = argv[0];
		arg0 = *argptr++;
		setinputfile(arg0, 0);
		commandname = arg0;
	}
	/* POSIX 1003.2: first arg after -c cmd is $0, remainder $1... */
	if (argptr && minusc && *argptr)
		arg0 = *argptr++;

	shellparam.p = argptr;
	shellparam.optind = 1;
	shellparam.optoff = -1;
	/* assert(shellparam.malloc == 0 && shellparam.nparam == 0); */
	while (*argptr) {
		shellparam.nparam++;
		argptr++;
	}
	optschanged();
}



/*
 * Process shell options.  The global variable argptr contains a pointer
 * to the argument list; we advance it past the options.
 */

static void
options(cmdline)
	int cmdline;
{
	char *p;
	int val;
	int c;

	if (cmdline)
		minusc = NULL;
	while ((p = *argptr) != NULL) {
		argptr++;
		if ((c = *p++) == '-') {
			val = 1;
			if (p[0] == '\0' || (p[0] == '-' && p[1] == '\0')) {
				if (!cmdline) {
					/* "-" means turn off -x and -v */
					if (p[0] == '\0')
						xflag = vflag = 0;
					/* "--" means reset params */
					else if (*argptr == NULL)
						setparam(argptr);
				}
				break;    /* "-" or  "--" terminates options */
			}
		} else if (c == '+') {
			val = 0;
		} else {
			argptr--;
			break;
		}
		while ((c = *p++) != '\0') {
			if (c == 'c' && cmdline) {
				char *q;
#ifdef NOHACK   /* removing this code allows sh -ce 'foo' for compat */
				if (*p == '\0')
#endif
					q = *argptr++;
				if (q == NULL || minusc != NULL)
					error("Bad -c option");
				minusc = q;
#ifdef NOHACK
				break;
#endif
			} else if (c == 'o') {
				minus_o(*argptr, val);
				if (*argptr)
					argptr++;
			} else {
				setoption(c, val);
			}
		}
	}
}

static void
minus_o(name, val)
	char *name;
	int val;
{
	int i;

	if (name == NULL) {
		out1str("Current option settings\n");
		for (i = 0; i < NOPTS; i++)
			out1fmt("%-16s%s\n", optent_name(optlist[i]),
				optent_val(i) ? "on" : "off");
	} else {
		for (i = 0; i < NOPTS; i++)
			if (equal(name, optent_name(optlist[i]))) {
				setoption(optent_letter(optlist[i]), val);
				return;
			}
		error("Illegal option -o %s", name);
	}
}


static void
setoption(int flag, int val)
{
	int i;

	for (i = 0; i < NOPTS; i++)
		if (optent_letter(optlist[i]) == flag) {
			optent_val(i) = val;
			if (val) {
				/* #%$ hack for ksh semantics */
				if (flag == 'V')
					Eflag = 0;
				else if (flag == 'E')
					Vflag = 0;
			}
			return;
		}
	error("Illegal option -%c", flag);
	/* NOTREACHED */
}



/*
 * Set the shell parameters.
 */

static void
setparam(char **argv)
{
	char **newparam;
	char **ap;
	int nparam;

	for (nparam = 0 ; argv[nparam] ; nparam++);
	ap = newparam = ckmalloc((nparam + 1) * sizeof *ap);
	while (*argv) {
		*ap++ = savestr(*argv++);
	}
	*ap = NULL;
	freeparam(&shellparam);
	shellparam.malloc = 1;
	shellparam.nparam = nparam;
	shellparam.p = newparam;
	shellparam.optind = 1;
	shellparam.optoff = -1;
}


/*
 * Free the list of positional parameters.
 */

static void
freeparam(volatile struct shparam *param)
{
	char **ap;

	if (param->malloc) {
		for (ap = param->p ; *ap ; ap++)
			ckfree(*ap);
		ckfree(param->p);
	}
}



/*
 * The shift builtin command.
 */

static int
shiftcmd(argc, argv)
	int argc;
	char **argv;
{
	int n;
	char **ap1, **ap2;

	n = 1;
	if (argc > 1)
		n = number(argv[1]);
	if (n > shellparam.nparam)
		error("can't shift that many");
	INTOFF;
	shellparam.nparam -= n;
	for (ap1 = shellparam.p ; --n >= 0 ; ap1++) {
		if (shellparam.malloc)
			ckfree(*ap1);
	}
	ap2 = shellparam.p;
	while ((*ap2++ = *ap1++) != NULL);
	shellparam.optind = 1;
	shellparam.optoff = -1;
	INTON;
	return 0;
}



/*
 * The set command builtin.
 */

static int
setcmd(argc, argv)
	int argc;
	char **argv;
{
	if (argc == 1)
		return showvarscmd(argc, argv);
	INTOFF;
	options(0);
	optschanged();
	if (*argptr != NULL) {
		setparam(argptr);
	}
	INTON;
	return 0;
}


static void
getoptsreset(const char *value)
{
	shellparam.optind = number(value);
	shellparam.optoff = -1;
}

#ifdef BB_LOCALE_SUPPORT
static void change_lc_all(const char *value)
{
	if(value != 0 && *value != 0)
		setlocale(LC_ALL, value);
}

static void change_lc_ctype(const char *value)
{
	if(value != 0 && *value != 0)
		setlocale(LC_CTYPE, value);
}

#endif

#ifdef ASH_GETOPTS
/*
 * The getopts builtin.  Shellparam.optnext points to the next argument
 * to be processed.  Shellparam.optptr points to the next character to
 * be processed in the current argument.  If shellparam.optnext is NULL,
 * then it's the first time getopts has been called.
 */

static int
getoptscmd(argc, argv)
	int argc;
	char **argv;
{
	char **optbase;

	if (argc < 3)
		error("Usage: getopts optstring var [arg]");
	else if (argc == 3) {
		optbase = shellparam.p;
		if (shellparam.optind > shellparam.nparam + 1) {
			shellparam.optind = 1;
			shellparam.optoff = -1;
		}
	}
	else {
		optbase = &argv[3];
		if (shellparam.optind > argc - 2) {
			shellparam.optind = 1;
			shellparam.optoff = -1;
		}
	}

	return getopts(argv[1], argv[2], optbase, &shellparam.optind,
		       &shellparam.optoff);
}

/*
 * Safe version of setvar, returns 1 on success 0 on failure.
 */

static int
setvarsafe(name, val, flags)
	const char *name, *val;
	int flags;
{
	struct jmploc jmploc;
	struct jmploc *volatile savehandler = handler;
	int err = 0;
#ifdef __GNUC__
	(void) &err;
#endif

	if (setjmp(jmploc.loc))
		err = 1;
	else {
		handler = &jmploc;
		setvar(name, val, flags);
	}
	handler = savehandler;
	return err;
}

static int
getopts(optstr, optvar, optfirst, myoptind, optoff)
	char *optstr;
	char *optvar;
	char **optfirst;
	int *myoptind;
	int *optoff;
{
	char *p, *q;
	char c = '?';
	int done = 0;
	int err = 0;
	char s[10];
	char **optnext = optfirst + *myoptind - 1;

	if (*myoptind <= 1 || *optoff < 0 || !(*(optnext - 1)) ||
	    strlen(*(optnext - 1)) < *optoff)
		p = NULL;
	else
		p = *(optnext - 1) + *optoff;
	if (p == NULL || *p == '\0') {
		/* Current word is done, advance */
		if (optnext == NULL)
			return 1;
		p = *optnext;
		if (p == NULL || *p != '-' || *++p == '\0') {
atend:
			*myoptind = optnext - optfirst + 1;
			p = NULL;
			done = 1;
			goto out;
		}
		optnext++;
		if (p[0] == '-' && p[1] == '\0')        /* check for "--" */
			goto atend;
	}

	c = *p++;
	for (q = optstr; *q != c; ) {
		if (*q == '\0') {
			if (optstr[0] == ':') {
				s[0] = c;
				s[1] = '\0';
				err |= setvarsafe("OPTARG", s, 0);
			}
			else {
				outfmt(&errout, "Illegal option -%c\n", c);
				(void) unsetvar("OPTARG");
			}
			c = '?';
			goto bad;
		}
		if (*++q == ':')
			q++;
	}

	if (*++q == ':') {
		if (*p == '\0' && (p = *optnext) == NULL) {
			if (optstr[0] == ':') {
				s[0] = c;
				s[1] = '\0';
				err |= setvarsafe("OPTARG", s, 0);
				c = ':';
			}
			else {
				outfmt(&errout, "No arg for -%c option\n", c);
				(void) unsetvar("OPTARG");
				c = '?';
			}
			goto bad;
		}

		if (p == *optnext)
			optnext++;
		setvarsafe("OPTARG", p, 0);
		p = NULL;
	}
	else
		setvarsafe("OPTARG", "", 0);
	*myoptind = optnext - optfirst + 1;
	goto out;

bad:
	*myoptind = 1;
	p = NULL;
out:
	*optoff = p ? p - *(optnext - 1) : -1;
	fmtstr(s, sizeof(s), "%d", *myoptind);
	err |= setvarsafe("OPTIND", s, VNOFUNC);
	s[0] = c;
	s[1] = '\0';
	err |= setvarsafe(optvar, s, 0);
	if (err) {
		*myoptind = 1;
		*optoff = -1;
		flushall();
		exraise(EXERROR);
	}
	return done;
}
#endif

/*
 * XXX - should get rid of.  have all builtins use getopt(3).  the
 * library getopt must have the BSD extension static variable "optreset"
 * otherwise it can't be used within the shell safely.
 *
 * Standard option processing (a la getopt) for builtin routines.  The
 * only argument that is passed to nextopt is the option string; the
 * other arguments are unnecessary.  It return the character, or '\0' on
 * end of input.
 */

static int
nextopt(optstring)
	const char *optstring;
	{
	char *p;
	const char *q;
	char c;

	if ((p = optptr) == NULL || *p == '\0') {
		p = *argptr;
		if (p == NULL || *p != '-' || *++p == '\0')
			return '\0';
		argptr++;
		if (p[0] == '-' && p[1] == '\0')        /* check for "--" */
			return '\0';
	}
	c = *p++;
	for (q = optstring ; *q != c ; ) {
		if (*q == '\0')
			error("Illegal option -%c", c);
		if (*++q == ':')
			q++;
	}
	if (*++q == ':') {
		if (*p == '\0' && (p = *argptr++) == NULL)
			error("No arg for -%c option", c);
		optionarg = p;
		p = NULL;
	}
	optptr = p;
	return c;
}


/*
 * Shell output routines.  We use our own output routines because:
 *      When a builtin command is interrupted we have to discard
 *              any pending output.
 *      When a builtin command appears in back quotes, we want to
 *              save the output of the command in a region obtained
 *              via malloc, rather than doing a fork and reading the
 *              output of the command via a pipe.
 *      Our output routines may be smaller than the stdio routines.
 */



#ifndef USE_GLIBC_STDIO
static void __outstr (const char *, size_t, struct output*);
#endif


#ifndef USE_GLIBC_STDIO
static void
__outstr(const char *p, size_t len, struct output *dest) {
	if (!dest->bufsize) {
		dest->nleft = 0;
	} else if (dest->buf == NULL) {
		if (len > dest->bufsize && dest->fd == MEM_OUT) {
			dest->bufsize = len;
		}
		INTOFF;
		dest->buf = ckmalloc(dest->bufsize);
		dest->nextc = dest->buf;
		dest->nleft = dest->bufsize;
		INTON;
	} else if (dest->fd == MEM_OUT) {
		int offset;

		offset = dest->bufsize;
		INTOFF;
		if (dest->bufsize >= len) {
			dest->bufsize <<= 1;
		} else {
			dest->bufsize += len;
		}
		dest->buf = ckrealloc(dest->buf, dest->bufsize);
		dest->nleft = dest->bufsize - offset;
		dest->nextc = dest->buf + offset;
		INTON;
	} else {
		flushout(dest);
	}

	if (len < dest->nleft) {
		dest->nleft -= len;
		memcpy(dest->nextc, p, len);
		dest->nextc += len;
		return;
	}

	if (xwrite(dest->fd, p, len) < len)
		dest->flags |= OUTPUT_ERR;
}
#endif


static void
outstr(const char *p, struct output *file)
{
#ifdef USE_GLIBC_STDIO
	INTOFF;
	fputs(p, file->stream);
	INTON;
#else
	size_t len;

	if (!*p) {
		return;
	}
	len = strlen(p);
	if ((file->nleft -= len) > 0) {
		memcpy(file->nextc, p, len);
		file->nextc += len;
		return;
	}
	__outstr(p, len, file);
#endif
}


#ifndef USE_GLIBC_STDIO


static void
outcslow(c, dest)
	char c;
	struct output *dest;
	{
	__outstr(&c, 1, dest);
}
#endif


static void
flushall() {
	flushout(&output);
#ifdef FLUSHERR
	flushout(&errout);
#endif
}


static void
flushout(dest)
	struct output *dest;
	{
#ifdef USE_GLIBC_STDIO
	INTOFF;
	fflush(dest->stream);
	INTON;
#else
	size_t len;

	len = dest->nextc - dest->buf;
	if (dest->buf == NULL || !len || dest->fd < 0)
		return;
	dest->nextc = dest->buf;
	dest->nleft = dest->bufsize;
	if (xwrite(dest->fd, dest->buf, len) < len)
		dest->flags |= OUTPUT_ERR;
#endif
}


static void
freestdout() {
	if (output.buf) {
		INTOFF;
		ckfree(output.buf);
		output.buf = NULL;
		output.nleft = 0;
		INTON;
	}
	output.flags = 0;
}


static void
#ifdef __STDC__
outfmt(struct output *file, const char *fmt, ...)
#else
static void
outfmt(va_alist)
	va_dcl
#endif
{
	va_list ap;
#ifndef __STDC__
	struct output *file;
	const char *fmt;

	va_start(ap);
	file = va_arg(ap, struct output *);
	fmt = va_arg(ap, const char *);
#else
	va_start(ap, fmt);
#endif
	doformat(file, fmt, ap);
	va_end(ap);
}


static void
#ifdef __STDC__
out1fmt(const char *fmt, ...)
#else
out1fmt(va_alist)
	va_dcl
#endif
{
	va_list ap;
#ifndef __STDC__
	const char *fmt;

	va_start(ap);
	fmt = va_arg(ap, const char *);
#else
	va_start(ap, fmt);
#endif
	doformat(out1, fmt, ap);
	va_end(ap);
}

static void
#ifdef __STDC__
fmtstr(char *outbuf, size_t length, const char *fmt, ...)
#else
fmtstr(va_alist)
	va_dcl
#endif
{
	va_list ap;
#ifndef __STDC__
	char *outbuf;
	size_t length;
	const char *fmt;

	va_start(ap);
	outbuf = va_arg(ap, char *);
	length = va_arg(ap, size_t);
	fmt = va_arg(ap, const char *);
#else
	va_start(ap, fmt);
#endif
	INTOFF;
	vsnprintf(outbuf, length, fmt, ap);
	INTON;
}

#ifndef USE_GLIBC_STDIO

static void
doformat(struct output *dest, const char *f, va_list ap)
{
	char *pm;
	int size = BUFSIZ;

	while(size) {
		int nchars;

		pm = xmalloc(size);
		nchars = vsnprintf(pm, size, f, ap);
		if(nchars > -1) {
			outstr(pm, dest);
			size = 0;
			}
		else
			size *= 2;
		free(pm);
	}
}
#endif



/*
 * Version of write which resumes after a signal is caught.
 */

static int
xwrite(int fd, const char *buf, int nbytes)
{
	int ntry;
	int i;
	int n;

	n = nbytes;
	ntry = 0;
	for (;;) {
		i = write(fd, buf, n);
		if (i > 0) {
			if ((n -= i) <= 0)
				return nbytes;
			buf += i;
			ntry = 0;
		} else if (i == 0) {
			if (++ntry > 10)
				return nbytes - n;
		} else if (errno != EINTR) {
			return -1;
		}
	}
}


#ifdef USE_GLIBC_STDIO
static void initstreams() {
	output.stream = stdout;
	errout.stream = stderr;
}


static void
openmemout() {
	INTOFF;
	memout.stream = open_memstream(&memout.buf, &memout.bufsize);
	INTON;
}


static int
__closememout() {
	int error;
	error = fclose(memout.stream);
	memout.stream = NULL;
	return error;
}
#endif
/*
 * Shell command parser.
 */

#define EOFMARKLEN 79



struct heredoc {
	struct heredoc *next;   /* next here document in list */
	union node *here;               /* redirection node */
	char *eofmark;          /* string indicating end of input */
	int striptabs;          /* if set, strip leading tabs */
};

static struct heredoc *heredoclist;     /* list of here documents to read */
static int parsebackquote;              /* nonzero if we are inside backquotes */
static int doprompt;                    /* if set, prompt the user */
static int needprompt;                  /* true if interactive and at start of line */
static int lasttoken;                   /* last token read */

static char *wordtext;                  /* text of last word returned by readtoken */

static struct nodelist *backquotelist;
static union node *redirnode;
struct heredoc *heredoc;
static int quoteflag;                   /* set if (part of) last token was quoted */
static int startlinno;                  /* line # where last token started */


static union node *list (int);
static union node *andor (void);
static union node *pipeline (void);
static union node *command (void);
static union node *simplecmd (void);
static void parsefname (void);
static void parseheredoc (void);
static int peektoken (void);
static int readtoken (void);
static int xxreadtoken (void);
static int readtoken1 (int, char const *, char *, int);
static int noexpand (char *);
static void synexpect (int) __attribute__((noreturn));
static void synerror (const char *) __attribute__((noreturn));
static void setprompt (int);


/*
 * Read and parse a command.  Returns NEOF on end of file.  (NULL is a
 * valid parse tree indicating a blank line.)
 */

static union node *
parsecmd(int interact)
{
	int t;

	tokpushback = 0;
	doprompt = interact;
	if (doprompt)
		setprompt(1);
	else
		setprompt(0);
	needprompt = 0;
	t = readtoken();
	if (t == TEOF)
		return NEOF;
	if (t == TNL)
		return NULL;
	tokpushback++;
	return list(1);
}


static union node *
list(nlflag)
	int nlflag;
{
	union node *n1, *n2, *n3;
	int tok;

	checkkwd = 2;
	if (nlflag == 0 && tokendlist[peektoken()])
		return NULL;
	n1 = NULL;
	for (;;) {
		n2 = andor();
		tok = readtoken();
		if (tok == TBACKGND) {
			if (n2->type == NCMD || n2->type == NPIPE) {
				n2->ncmd.backgnd = 1;
			} else if (n2->type == NREDIR) {
				n2->type = NBACKGND;
			} else {
				n3 = (union node *)stalloc(sizeof (struct nredir));
				n3->type = NBACKGND;
				n3->nredir.n = n2;
				n3->nredir.redirect = NULL;
				n2 = n3;
			}
		}
		if (n1 == NULL) {
			n1 = n2;
		}
		else {
			n3 = (union node *)stalloc(sizeof (struct nbinary));
			n3->type = NSEMI;
			n3->nbinary.ch1 = n1;
			n3->nbinary.ch2 = n2;
			n1 = n3;
		}
		switch (tok) {
		case TBACKGND:
		case TSEMI:
			tok = readtoken();
			/* fall through */
		case TNL:
			if (tok == TNL) {
				parseheredoc();
				if (nlflag)
					return n1;
			} else {
				tokpushback++;
			}
			checkkwd = 2;
			if (tokendlist[peektoken()])
				return n1;
			break;
		case TEOF:
			if (heredoclist)
				parseheredoc();
			else
				pungetc();              /* push back EOF on input */
			return n1;
		default:
			if (nlflag)
				synexpect(-1);
			tokpushback++;
			return n1;
		}
	}
}



static union node *
andor() {
	union node *n1, *n2, *n3;
	int t;

	checkkwd = 1;
	n1 = pipeline();
	for (;;) {
		if ((t = readtoken()) == TAND) {
			t = NAND;
		} else if (t == TOR) {
			t = NOR;
		} else {
			tokpushback++;
			return n1;
		}
		checkkwd = 2;
		n2 = pipeline();
		n3 = (union node *)stalloc(sizeof (struct nbinary));
		n3->type = t;
		n3->nbinary.ch1 = n1;
		n3->nbinary.ch2 = n2;
		n1 = n3;
	}
}



static union node *
pipeline() {
	union node *n1, *n2, *pipenode;
	struct nodelist *lp, *prev;
	int negate;

	negate = 0;
	TRACE(("pipeline: entered\n"));
	if (readtoken() == TNOT) {
		negate = !negate;
		checkkwd = 1;
	} else
		tokpushback++;
	n1 = command();
	if (readtoken() == TPIPE) {
		pipenode = (union node *)stalloc(sizeof (struct npipe));
		pipenode->type = NPIPE;
		pipenode->npipe.backgnd = 0;
		lp = (struct nodelist *)stalloc(sizeof (struct nodelist));
		pipenode->npipe.cmdlist = lp;
		lp->n = n1;
		do {
			prev = lp;
			lp = (struct nodelist *)stalloc(sizeof (struct nodelist));
			checkkwd = 2;
			lp->n = command();
			prev->next = lp;
		} while (readtoken() == TPIPE);
		lp->next = NULL;
		n1 = pipenode;
	}
	tokpushback++;
	if (negate) {
		n2 = (union node *)stalloc(sizeof (struct nnot));
		n2->type = NNOT;
		n2->nnot.com = n1;
		return n2;
	} else
		return n1;
}



static union node *
command() {
	union node *n1, *n2;
	union node *ap, **app;
	union node *cp, **cpp;
	union node *redir, **rpp;
	int t;

	redir = NULL;
	n1 = NULL;
	rpp = &redir;

	switch (readtoken()) {
	case TIF:
		n1 = (union node *)stalloc(sizeof (struct nif));
		n1->type = NIF;
		n1->nif.test = list(0);
		if (readtoken() != TTHEN)
			synexpect(TTHEN);
		n1->nif.ifpart = list(0);
		n2 = n1;
		while (readtoken() == TELIF) {
			n2->nif.elsepart = (union node *)stalloc(sizeof (struct nif));
			n2 = n2->nif.elsepart;
			n2->type = NIF;
			n2->nif.test = list(0);
			if (readtoken() != TTHEN)
				synexpect(TTHEN);
			n2->nif.ifpart = list(0);
		}
		if (lasttoken == TELSE)
			n2->nif.elsepart = list(0);
		else {
			n2->nif.elsepart = NULL;
			tokpushback++;
		}
		if (readtoken() != TFI)
			synexpect(TFI);
		checkkwd = 1;
		break;
	case TWHILE:
	case TUNTIL: {
		int got;
		n1 = (union node *)stalloc(sizeof (struct nbinary));
		n1->type = (lasttoken == TWHILE)? NWHILE : NUNTIL;
		n1->nbinary.ch1 = list(0);
		if ((got=readtoken()) != TDO) {
TRACE(("expecting DO got %s %s\n", tokname[got], got == TWORD ? wordtext : ""));
			synexpect(TDO);
		}
		n1->nbinary.ch2 = list(0);
		if (readtoken() != TDONE)
			synexpect(TDONE);
		checkkwd = 1;
		break;
	}
	case TFOR:
		if (readtoken() != TWORD || quoteflag || ! goodname(wordtext))
			synerror("Bad for loop variable");
		n1 = (union node *)stalloc(sizeof (struct nfor));
		n1->type = NFOR;
		n1->nfor.var = wordtext;
		checkkwd = 1;
		if (readtoken() == TIN) {
			app = &ap;
			while (readtoken() == TWORD) {
				n2 = (union node *)stalloc(sizeof (struct narg));
				n2->type = NARG;
				n2->narg.text = wordtext;
				n2->narg.backquote = backquotelist;
				*app = n2;
				app = &n2->narg.next;
			}
			*app = NULL;
			n1->nfor.args = ap;
			if (lasttoken != TNL && lasttoken != TSEMI)
				synexpect(-1);
		} else {
			static char argvars[5] = {CTLVAR, VSNORMAL|VSQUOTE,
								   '@', '=', '\0'};
			n2 = (union node *)stalloc(sizeof (struct narg));
			n2->type = NARG;
			n2->narg.text = argvars;
			n2->narg.backquote = NULL;
			n2->narg.next = NULL;
			n1->nfor.args = n2;
			/*
			 * Newline or semicolon here is optional (but note
			 * that the original Bourne shell only allowed NL).
			 */
			if (lasttoken != TNL && lasttoken != TSEMI)
				tokpushback++;
		}
		checkkwd = 2;
		if (readtoken() != TDO)
			synexpect(TDO);
		n1->nfor.body = list(0);
		if (readtoken() != TDONE)
			synexpect(TDONE);
		checkkwd = 1;
		break;
	case TCASE:
		n1 = (union node *)stalloc(sizeof (struct ncase));
		n1->type = NCASE;
		if (readtoken() != TWORD)
			synexpect(TWORD);
		n1->ncase.expr = n2 = (union node *)stalloc(sizeof (struct narg));
		n2->type = NARG;
		n2->narg.text = wordtext;
		n2->narg.backquote = backquotelist;
		n2->narg.next = NULL;
		do {
			checkkwd = 1;
		} while (readtoken() == TNL);
		if (lasttoken != TIN)
			synerror("expecting \"in\"");
		cpp = &n1->ncase.cases;
		checkkwd = 2, readtoken();
		do {
			if (lasttoken == TLP)
				readtoken();
			*cpp = cp = (union node *)stalloc(sizeof (struct nclist));
			cp->type = NCLIST;
			app = &cp->nclist.pattern;
			for (;;) {
				*app = ap = (union node *)stalloc(sizeof (struct narg));
				ap->type = NARG;
				ap->narg.text = wordtext;
				ap->narg.backquote = backquotelist;
				if (checkkwd = 2, readtoken() != TPIPE)
					break;
				app = &ap->narg.next;
				readtoken();
			}
			ap->narg.next = NULL;
			if (lasttoken != TRP)
				synexpect(TRP);
			cp->nclist.body = list(0);

			checkkwd = 2;
			if ((t = readtoken()) != TESAC) {
				if (t != TENDCASE)
					synexpect(TENDCASE);
				else
					checkkwd = 2, readtoken();
			}
			cpp = &cp->nclist.next;
		} while(lasttoken != TESAC);
		*cpp = NULL;
		checkkwd = 1;
		break;
	case TLP:
		n1 = (union node *)stalloc(sizeof (struct nredir));
		n1->type = NSUBSHELL;
		n1->nredir.n = list(0);
		n1->nredir.redirect = NULL;
		if (readtoken() != TRP)
			synexpect(TRP);
		checkkwd = 1;
		break;
	case TBEGIN:
		n1 = list(0);
		if (readtoken() != TEND)
			synexpect(TEND);
		checkkwd = 1;
		break;
	/* Handle an empty command like other simple commands.  */
	case TSEMI:
	case TAND:
	case TOR:
	case TNL:
	case TEOF:
	case TRP:
	case TBACKGND:
		/*
		 * An empty command before a ; doesn't make much sense, and
		 * should certainly be disallowed in the case of `if ;'.
		 */
		if (!redir)
			synexpect(-1);
	case TWORD:
	case TREDIR:
		tokpushback++;
		n1 = simplecmd();
		return n1;
	default:
		synexpect(-1);
		/* NOTREACHED */
	}

	/* Now check for redirection which may follow command */
	while (readtoken() == TREDIR) {
		*rpp = n2 = redirnode;
		rpp = &n2->nfile.next;
		parsefname();
	}
	tokpushback++;
	*rpp = NULL;
	if (redir) {
		if (n1->type != NSUBSHELL) {
			n2 = (union node *)stalloc(sizeof (struct nredir));
			n2->type = NREDIR;
			n2->nredir.n = n1;
			n1 = n2;
		}
		n1->nredir.redirect = redir;
	}

	return n1;
}


static union node *
simplecmd() {
	union node *args, **app;
	union node *n = NULL;
	union node *vars, **vpp;
	union node **rpp, *redir;

	args = NULL;
	app = &args;
	vars = NULL;
	vpp = &vars;
	redir = NULL;
	rpp = &redir;

#ifdef ASH_ALIAS
	checkalias = 2;
#endif
	for (;;) {
		switch (readtoken()) {
		case TWORD:
		case TASSIGN:
			n = (union node *)stalloc(sizeof (struct narg));
			n->type = NARG;
			n->narg.text = wordtext;
			n->narg.backquote = backquotelist;
			if (lasttoken == TWORD) {
				*app = n;
				app = &n->narg.next;
			} else {
				*vpp = n;
				vpp = &n->narg.next;
			}
			break;
		case TREDIR:
			*rpp = n = redirnode;
			rpp = &n->nfile.next;
			parsefname();   /* read name of redirection file */
			break;
		case TLP:
			if (
				args && app == &args->narg.next &&
				!vars && !redir
			) {
				/* We have a function */
				if (readtoken() != TRP)
					synexpect(TRP);
				n->type = NDEFUN;
				checkkwd = 2;
				n->narg.next = command();
				return n;
			}
			/* fall through */
		default:
			tokpushback++;
			goto out;
		}
	}
out:
	*app = NULL;
	*vpp = NULL;
	*rpp = NULL;
	n = (union node *)stalloc(sizeof (struct ncmd));
	n->type = NCMD;
	n->ncmd.backgnd = 0;
	n->ncmd.args = args;
	n->ncmd.assign = vars;
	n->ncmd.redirect = redir;
	return n;
}

static union node *
makename(void) {
	union node *n;

	n = (union node *)stalloc(sizeof (struct narg));
	n->type = NARG;
	n->narg.next = NULL;
	n->narg.text = wordtext;
	n->narg.backquote = backquotelist;
	return n;
}

static void fixredir(union node *n, const char *text, int err)
{
	TRACE(("Fix redir %s %d\n", text, err));
	if (!err)
		n->ndup.vname = NULL;

	if (is_digit(text[0]) && text[1] == '\0')
		n->ndup.dupfd = digit_val(text[0]);
	else if (text[0] == '-' && text[1] == '\0')
		n->ndup.dupfd = -1;
	else {

		if (err)
			synerror("Bad fd number");
		else
			n->ndup.vname = makename();
	}
}


static void
parsefname(void) {
	union node *n = redirnode;

	if (readtoken() != TWORD)
		synexpect(-1);
	if (n->type == NHERE) {
		struct heredoc *here = heredoc;
		struct heredoc *p;
		int i;

		if (quoteflag == 0)
			n->type = NXHERE;
		TRACE(("Here document %d\n", n->type));
		if (here->striptabs) {
			while (*wordtext == '\t')
				wordtext++;
		}
		if (! noexpand(wordtext) || (i = strlen(wordtext)) == 0 || i > EOFMARKLEN)
			synerror("Illegal eof marker for << redirection");
		rmescapes(wordtext);
		here->eofmark = wordtext;
		here->next = NULL;
		if (heredoclist == NULL)
			heredoclist = here;
		else {
			for (p = heredoclist ; p->next ; p = p->next);
			p->next = here;
		}
	} else if (n->type == NTOFD || n->type == NFROMFD) {
		fixredir(n, wordtext, 0);
	} else {
		n->nfile.fname = makename();
	}
}


/*
 * Input any here documents.
 */

static void
parseheredoc() {
	struct heredoc *here;
	union node *n;

	while (heredoclist) {
		here = heredoclist;
		heredoclist = here->next;
		if (needprompt) {
			setprompt(2);
			needprompt = 0;
		}
		readtoken1(pgetc(), here->here->type == NHERE? SQSYNTAX : DQSYNTAX,
				here->eofmark, here->striptabs);
		n = (union node *)stalloc(sizeof (struct narg));
		n->narg.type = NARG;
		n->narg.next = NULL;
		n->narg.text = wordtext;
		n->narg.backquote = backquotelist;
		here->here->nhere.doc = n;
	}
}

static int
peektoken() {
	int t;

	t = readtoken();
	tokpushback++;
	return (t);
}

static int
readtoken() {
	int t;
#ifdef ASH_ALIAS
	int savecheckkwd = checkkwd;
	int savecheckalias = checkalias;
	struct alias *ap;
#endif

#ifdef DEBUG
	int alreadyseen = tokpushback;
#endif

#ifdef ASH_ALIAS
top:
#endif

	t = xxreadtoken();

#ifdef ASH_ALIAS
	checkalias = savecheckalias;
#endif

	if (checkkwd) {
		/*
		 * eat newlines
		 */
		if (checkkwd == 2) {
			checkkwd = 0;
			while (t == TNL) {
				parseheredoc();
				t = xxreadtoken();
			}
		}
		checkkwd = 0;
		/*
		 * check for keywords
		 */
		if (t == TWORD && !quoteflag)
		{
			const char *const *pp;

			if ((pp = findkwd(wordtext))) {
				lasttoken = t = pp - parsekwd + KWDOFFSET;
				TRACE(("keyword %s recognized\n", tokname[t]));
				goto out;
			}
		}
	}

#ifdef ASH_ALIAS
	if (t != TWORD) {
		if (t != TREDIR) {
			checkalias = 0;
		}
	} else if (checkalias == 2 && isassignment(wordtext)) {
		lasttoken = t = TASSIGN;
	} else if (checkalias) {
		if (!quoteflag && (ap = lookupalias(wordtext, 1)) != NULL) {
			if (*ap->val) {
				pushstring(ap->val, strlen(ap->val), ap);
			}
			checkkwd = savecheckkwd;
			goto top;
		}
		checkalias = 0;
	}
#endif
out:
#ifdef DEBUG
	if (!alreadyseen)
	    TRACE(("token %s %s\n", tokname[t], t == TWORD || t == TASSIGN ? wordtext : ""));
	else
	    TRACE(("reread token %s %s\n", tokname[t], t == TWORD || t == TASSIGN ? wordtext : ""));
#endif
	return (t);
}


/*
 * Read the next input token.
 * If the token is a word, we set backquotelist to the list of cmds in
 *      backquotes.  We set quoteflag to true if any part of the word was
 *      quoted.
 * If the token is TREDIR, then we set redirnode to a structure containing
 *      the redirection.
 * In all cases, the variable startlinno is set to the number of the line
 *      on which the token starts.
 *
 * [Change comment:  here documents and internal procedures]
 * [Readtoken shouldn't have any arguments.  Perhaps we should make the
 *  word parsing code into a separate routine.  In this case, readtoken
 *  doesn't need to have any internal procedures, but parseword does.
 *  We could also make parseoperator in essence the main routine, and
 *  have parseword (readtoken1?) handle both words and redirection.]
 */

#define RETURN(token)   return lasttoken = token

static int
xxreadtoken() {
	int c;

	if (tokpushback) {
		tokpushback = 0;
		return lasttoken;
	}
	if (needprompt) {
		setprompt(2);
		needprompt = 0;
	}
	startlinno = plinno;
	for (;;) {      /* until token or start of word found */
		c = pgetc_macro();
		switch (c) {
		case ' ': case '\t':
		case PEOA:
			continue;
		case '#':
			while ((c = pgetc()) != '\n' && c != PEOF);
			pungetc();
			continue;
		case '\\':
			if (pgetc() == '\n') {
				startlinno = ++plinno;
				if (doprompt)
					setprompt(2);
				else
					setprompt(0);
				continue;
			}
			pungetc();
			goto breakloop;
		case '\n':
			plinno++;
			needprompt = doprompt;
			RETURN(TNL);
		case PEOF:
			RETURN(TEOF);
		case '&':
			if (pgetc() == '&')
				RETURN(TAND);
			pungetc();
			RETURN(TBACKGND);
		case '|':
			if (pgetc() == '|')
				RETURN(TOR);
			pungetc();
			RETURN(TPIPE);
		case ';':
			if (pgetc() == ';')
				RETURN(TENDCASE);
			pungetc();
			RETURN(TSEMI);
		case '(':
			RETURN(TLP);
		case ')':
			RETURN(TRP);
		default:
			goto breakloop;
		}
	}
breakloop:
	return readtoken1(c, BASESYNTAX, (char *)NULL, 0);
#undef RETURN
}



/*
 * If eofmark is NULL, read a word or a redirection symbol.  If eofmark
 * is not NULL, read a here document.  In the latter case, eofmark is the
 * word which marks the end of the document and striptabs is true if
 * leading tabs should be stripped from the document.  The argument firstc
 * is the first character of the input token or document.
 *
 * Because C does not have internal subroutines, I have simulated them
 * using goto's to implement the subroutine linkage.  The following macros
 * will run code that appears at the end of readtoken1.
 */

#define CHECKEND()      {goto checkend; checkend_return:;}
#define PARSEREDIR()    {goto parseredir; parseredir_return:;}
#define PARSESUB()      {goto parsesub; parsesub_return:;}
#define PARSEBACKQOLD() {oldstyle = 1; goto parsebackq; parsebackq_oldreturn:;}
#define PARSEBACKQNEW() {oldstyle = 0; goto parsebackq; parsebackq_newreturn:;}
#define PARSEARITH()    {goto parsearith; parsearith_return:;}

static int
readtoken1(firstc, syntax, eofmark, striptabs)
	int firstc;
	char const *syntax;
	char *eofmark;
	int striptabs;
	{
	int c = firstc;
	char *out;
	int len;
	char line[EOFMARKLEN + 1];
	struct nodelist *bqlist;
	int quotef;
	int dblquote;
	int varnest;    /* levels of variables expansion */
	int arinest;    /* levels of arithmetic expansion */
	int parenlevel; /* levels of parens in arithmetic */
	int dqvarnest;  /* levels of variables expansion within double quotes */
	int oldstyle;
	char const *prevsyntax; /* syntax before arithmetic */
#if __GNUC__
	/* Avoid longjmp clobbering */
	(void) &out;
	(void) &quotef;
	(void) &dblquote;
	(void) &varnest;
	(void) &arinest;
	(void) &parenlevel;
	(void) &dqvarnest;
	(void) &oldstyle;
	(void) &prevsyntax;
	(void) &syntax;
#endif

	startlinno = plinno;
	dblquote = 0;
	if (syntax == DQSYNTAX)
		dblquote = 1;
	quotef = 0;
	bqlist = NULL;
	varnest = 0;
	arinest = 0;
	parenlevel = 0;
	dqvarnest = 0;

	STARTSTACKSTR(out);
	loop: { /* for each line, until end of word */
		CHECKEND();     /* set c to PEOF if at end of here document */
		for (;;) {      /* until end of line or end of word */
			CHECKSTRSPACE(3, out);  /* permit 3 calls to USTPUTC */
			switch(syntax[c]) {
			case CNL:       /* '\n' */
				if (syntax == BASESYNTAX)
					goto endword;   /* exit outer loop */
				USTPUTC(c, out);
				plinno++;
				if (doprompt)
					setprompt(2);
				else
					setprompt(0);
				c = pgetc();
				goto loop;              /* continue outer loop */
			case CWORD:
				USTPUTC(c, out);
				break;
			case CCTL:
				if ((eofmark == NULL || dblquote) &&
				    dqvarnest == 0)
					USTPUTC(CTLESC, out);
				USTPUTC(c, out);
				break;
			case CBACK:     /* backslash */
				c = pgetc2();
				if (c == PEOF) {
					USTPUTC('\\', out);
					pungetc();
				} else if (c == '\n') {
					if (doprompt)
						setprompt(2);
					else
						setprompt(0);
				} else {
					if (dblquote && c != '\\' && c != '`' && c != '$'
							 && (c != '"' || eofmark != NULL))
						USTPUTC('\\', out);
					if (SQSYNTAX[c] == CCTL)
						USTPUTC(CTLESC, out);
					else if (eofmark == NULL)
						USTPUTC(CTLQUOTEMARK, out);
					USTPUTC(c, out);
					quotef++;
				}
				break;
			case CSQUOTE:
				if (eofmark == NULL)
					USTPUTC(CTLQUOTEMARK, out);
				syntax = SQSYNTAX;
				break;
			case CDQUOTE:
				if (eofmark == NULL)
					USTPUTC(CTLQUOTEMARK, out);
				syntax = DQSYNTAX;
				dblquote = 1;
				break;
			case CENDQUOTE:
				if (eofmark != NULL && arinest == 0 &&
				    varnest == 0) {
					USTPUTC(c, out);
				} else {
					if (arinest) {
						syntax = ARISYNTAX;
						dblquote = 0;
					} else if (eofmark == NULL &&
						   dqvarnest == 0) {
						syntax = BASESYNTAX;
						dblquote = 0;
					}
					quotef++;
				}
				break;
			case CVAR:      /* '$' */
				PARSESUB();             /* parse substitution */
				break;
			case CENDVAR:   /* '}' */
				if (varnest > 0) {
					varnest--;
					if (dqvarnest > 0) {
						dqvarnest--;
					}
					USTPUTC(CTLENDVAR, out);
				} else {
					USTPUTC(c, out);
				}
				break;
#ifdef ASH_MATH_SUPPORT
			case CLP:       /* '(' in arithmetic */
				parenlevel++;
				USTPUTC(c, out);
				break;
			case CRP:       /* ')' in arithmetic */
				if (parenlevel > 0) {
					USTPUTC(c, out);
					--parenlevel;
				} else {
					if (pgetc() == ')') {
						if (--arinest == 0) {
							USTPUTC(CTLENDARI, out);
							syntax = prevsyntax;
							if (syntax == DQSYNTAX)
								dblquote = 1;
							else
								dblquote = 0;
						} else
							USTPUTC(')', out);
					} else {
						/*
						 * unbalanced parens
						 *  (don't 2nd guess - no error)
						 */
						pungetc();
						USTPUTC(')', out);
					}
				}
				break;
#endif
			case CBQUOTE:   /* '`' */
				PARSEBACKQOLD();
				break;
			case CENDFILE:
				goto endword;           /* exit outer loop */
			case CIGN:
				break;
			default:
				if (varnest == 0)
					goto endword;   /* exit outer loop */
				if (c != PEOA) {
					USTPUTC(c, out);
				}
			}
			c = pgetc_macro();
		}
	}
endword:
	if (syntax == ARISYNTAX)
		synerror("Missing '))'");
	if (syntax != BASESYNTAX && ! parsebackquote && eofmark == NULL)
		synerror("Unterminated quoted string");
	if (varnest != 0) {
		startlinno = plinno;
		synerror("Missing '}'");
	}
	USTPUTC('\0', out);
	len = out - stackblock();
	out = stackblock();
	if (eofmark == NULL) {
		if ((c == '>' || c == '<')
		 && quotef == 0
		 && len <= 2
		 && (*out == '\0' || is_digit(*out))) {
			PARSEREDIR();
			return lasttoken = TREDIR;
		} else {
			pungetc();
		}
	}
	quoteflag = quotef;
	backquotelist = bqlist;
	grabstackblock(len);
	wordtext = out;
	return lasttoken = TWORD;
/* end of readtoken routine */



/*
 * Check to see whether we are at the end of the here document.  When this
 * is called, c is set to the first character of the next input line.  If
 * we are at the end of the here document, this routine sets the c to PEOF.
 */

checkend: {
	if (eofmark) {
#ifdef ASH_ALIAS
		if (c == PEOA) {
			c = pgetc2();
		}
#endif
		if (striptabs) {
			while (c == '\t') {
				c = pgetc2();
			}
		}
		if (c == *eofmark) {
			if (pfgets(line, sizeof line) != NULL) {
				char *p, *q;

				p = line;
				for (q = eofmark + 1 ; *q && *p == *q ; p++, q++);
				if (*p == '\n' && *q == '\0') {
					c = PEOF;
					plinno++;
					needprompt = doprompt;
				} else {
					pushstring(line, strlen(line), NULL);
				}
			}
		}
	}
	goto checkend_return;
}


/*
 * Parse a redirection operator.  The variable "out" points to a string
 * specifying the fd to be redirected.  The variable "c" contains the
 * first character of the redirection operator.
 */

parseredir: {
	char fd = *out;
	union node *np;

	np = (union node *)stalloc(sizeof (struct nfile));
	if (c == '>') {
		np->nfile.fd = 1;
		c = pgetc();
		if (c == '>')
			np->type = NAPPEND;
		else if (c == '&')
			np->type = NTOFD;
		else if (c == '|')
			np->type = NTOOV;
		else {
			np->type = NTO;
			pungetc();
		}
	} else {        /* c == '<' */
		np->nfile.fd = 0;
		switch (c = pgetc()) {
		case '<':
			if (sizeof (struct nfile) != sizeof (struct nhere)) {
				np = (union node *)stalloc(sizeof (struct nhere));
				np->nfile.fd = 0;
			}
			np->type = NHERE;
			heredoc = (struct heredoc *)stalloc(sizeof (struct heredoc));
			heredoc->here = np;
			if ((c = pgetc()) == '-') {
				heredoc->striptabs = 1;
			} else {
				heredoc->striptabs = 0;
				pungetc();
			}
			break;

		case '&':
			np->type = NFROMFD;
			break;

		case '>':
			np->type = NFROMTO;
			break;

		default:
			np->type = NFROM;
			pungetc();
			break;
		}
	}
	if (fd != '\0')
		np->nfile.fd = digit_val(fd);
	redirnode = np;
	goto parseredir_return;
}


/*
 * Parse a substitution.  At this point, we have read the dollar sign
 * and nothing else.
 */

parsesub: {
	int subtype;
	int typeloc;
	int flags;
	char *p;
	static const char types[] = "}-+?=";

	c = pgetc();
	if (
		c <= PEOA  ||
		(c != '(' && c != '{' && !is_name(c) && !is_special(c))
	) {
		USTPUTC('$', out);
		pungetc();
	} else if (c == '(') {  /* $(command) or $((arith)) */
		if (pgetc() == '(') {
			PARSEARITH();
		} else {
			pungetc();
			PARSEBACKQNEW();
		}
	} else {
		USTPUTC(CTLVAR, out);
		typeloc = out - stackblock();
		USTPUTC(VSNORMAL, out);
		subtype = VSNORMAL;
		if (c == '{') {
			c = pgetc();
			if (c == '#') {
				if ((c = pgetc()) == '}')
					c = '#';
				else
					subtype = VSLENGTH;
			}
			else
				subtype = 0;
		}
		if (c > PEOA && is_name(c)) {
			do {
				STPUTC(c, out);
				c = pgetc();
			} while (c > PEOA && is_in_name(c));
		} else if (is_digit(c)) {
			do {
				USTPUTC(c, out);
				c = pgetc();
			} while (is_digit(c));
		}
		else if (is_special(c)) {
			USTPUTC(c, out);
			c = pgetc();
		}
		else
badsub:                 synerror("Bad substitution");

		STPUTC('=', out);
		flags = 0;
		if (subtype == 0) {
			switch (c) {
			case ':':
				flags = VSNUL;
				c = pgetc();
				/*FALLTHROUGH*/
			default:
				p = strchr(types, c);
				if (p == NULL)
					goto badsub;
				subtype = p - types + VSNORMAL;
				break;
			case '%':
			case '#':
				{
					int cc = c;
					subtype = c == '#' ? VSTRIMLEFT :
							     VSTRIMRIGHT;
					c = pgetc();
					if (c == cc)
						subtype++;
					else
						pungetc();
					break;
				}
			}
		} else {
			pungetc();
		}
		if (dblquote || arinest)
			flags |= VSQUOTE;
		*(stackblock() + typeloc) = subtype | flags;
		if (subtype != VSNORMAL) {
			varnest++;
			if (dblquote) {
				dqvarnest++;
			}
		}
	}
	goto parsesub_return;
}


/*
 * Called to parse command substitutions.  Newstyle is set if the command
 * is enclosed inside $(...); nlpp is a pointer to the head of the linked
 * list of commands (passed by reference), and savelen is the number of
 * characters on the top of the stack which must be preserved.
 */

parsebackq: {
	struct nodelist **nlpp;
	int savepbq;
	union node *n;
	char *volatile str;
	struct jmploc jmploc;
	struct jmploc *volatile savehandler;
	int savelen;
	int saveprompt;
#ifdef __GNUC__
	(void) &saveprompt;
#endif

	savepbq = parsebackquote;
	if (setjmp(jmploc.loc)) {
		if (str)
			ckfree(str);
		parsebackquote = 0;
		handler = savehandler;
		longjmp(handler->loc, 1);
	}
	INTOFF;
	str = NULL;
	savelen = out - stackblock();
	if (savelen > 0) {
		str = ckmalloc(savelen);
		memcpy(str, stackblock(), savelen);
	}
	savehandler = handler;
	handler = &jmploc;
	INTON;
	if (oldstyle) {
		/* We must read until the closing backquote, giving special
		   treatment to some slashes, and then push the string and
		   reread it as input, interpreting it normally.  */
		char *pout;
		int pc;
		int psavelen;
		char *pstr;


		STARTSTACKSTR(pout);
		for (;;) {
			if (needprompt) {
				setprompt(2);
				needprompt = 0;
			}
			switch (pc = pgetc()) {
			case '`':
				goto done;

			case '\\':
				if ((pc = pgetc()) == '\n') {
					plinno++;
					if (doprompt)
						setprompt(2);
					else
						setprompt(0);
					/*
					 * If eating a newline, avoid putting
					 * the newline into the new character
					 * stream (via the STPUTC after the
					 * switch).
					 */
					continue;
				}
				if (pc != '\\' && pc != '`' && pc != '$'
				    && (!dblquote || pc != '"'))
					STPUTC('\\', pout);
				if (pc > PEOA) {
					break;
				}
				/* fall through */

			case PEOF:
#ifdef ASH_ALIAS
			case PEOA:
#endif
				startlinno = plinno;
				synerror("EOF in backquote substitution");

			case '\n':
				plinno++;
				needprompt = doprompt;
				break;

			default:
				break;
			}
			STPUTC(pc, pout);
		}
done:
		STPUTC('\0', pout);
		psavelen = pout - stackblock();
		if (psavelen > 0) {
			pstr = grabstackstr(pout);
			setinputstring(pstr);
		}
	}
	nlpp = &bqlist;
	while (*nlpp)
		nlpp = &(*nlpp)->next;
	*nlpp = (struct nodelist *)stalloc(sizeof (struct nodelist));
	(*nlpp)->next = NULL;
	parsebackquote = oldstyle;

	if (oldstyle) {
		saveprompt = doprompt;
		doprompt = 0;
	}

	n = list(0);

	if (oldstyle)
		doprompt = saveprompt;
	else {
		if (readtoken() != TRP)
			synexpect(TRP);
	}

	(*nlpp)->n = n;
	if (oldstyle) {
		/*
		 * Start reading from old file again, ignoring any pushed back
		 * tokens left from the backquote parsing
		 */
		popfile();
		tokpushback = 0;
	}
	while (stackblocksize() <= savelen)
		growstackblock();
	STARTSTACKSTR(out);
	if (str) {
		memcpy(out, str, savelen);
		STADJUST(savelen, out);
		INTOFF;
		ckfree(str);
		str = NULL;
		INTON;
	}
	parsebackquote = savepbq;
	handler = savehandler;
	if (arinest || dblquote)
		USTPUTC(CTLBACKQ | CTLQUOTE, out);
	else
		USTPUTC(CTLBACKQ, out);
	if (oldstyle)
		goto parsebackq_oldreturn;
	else
		goto parsebackq_newreturn;
}

/*
 * Parse an arithmetic expansion (indicate start of one and set state)
 */
parsearith: {

	if (++arinest == 1) {
		prevsyntax = syntax;
		syntax = ARISYNTAX;
		USTPUTC(CTLARI, out);
		if (dblquote)
			USTPUTC('"',out);
		else
			USTPUTC(' ',out);
	} else {
		/*
		 * we collapse embedded arithmetic expansion to
		 * parenthesis, which should be equivalent
		 */
		USTPUTC('(', out);
	}
	goto parsearith_return;
}

} /* end of readtoken */


/*
 * Returns true if the text contains nothing to expand (no dollar signs
 * or backquotes).
 */

static int
noexpand(text)
	char *text;
	{
	char *p;
	char c;

	p = text;
	while ((c = *p++) != '\0') {
		if (c == CTLQUOTEMARK)
			continue;
		if (c == CTLESC)
			p++;
		else if (BASESYNTAX[(int)c] == CCTL)
			return 0;
	}
	return 1;
}


/*
 * Return true if the argument is a legal variable name (a letter or
 * underscore followed by zero or more letters, underscores, and digits).
 */

static int
goodname(const char *name)
{
	const char *p;

	p = name;
	if (! is_name(*p))
		return 0;
	while (*++p) {
		if (! is_in_name(*p))
			return 0;
	}
	return 1;
}


/*
 * Called when an unexpected token is read during the parse.  The argument
 * is the token that is expected, or -1 if more than one type of token can
 * occur at this point.
 */

static void
synexpect(token)
	int token;
{
	char msg[64];

	if (token >= 0) {
		fmtstr(msg, 64, "%s unexpected (expecting %s)",
			tokname[lasttoken], tokname[token]);
	} else {
		fmtstr(msg, 64, "%s unexpected", tokname[lasttoken]);
	}
	synerror(msg);
	/* NOTREACHED */
}


static void
synerror(const char *msg)
{
	if (commandname)
		outfmt(&errout, "%s: %d: ", commandname, startlinno);
	outfmt(&errout, "Syntax error: %s\n", msg);
	error((char *)NULL);
	/* NOTREACHED */
}


/*
 * called by editline -- any expansions to the prompt
 *    should be added here.
 */
static const char *
getprompt(void *unused)
{
	switch (whichprompt) {
	case 0:
		return "";
	case 1:
		return ps1val();
	case 2:
		return ps2val();
	default:
		return "<internal prompt error>";
	}
}

static void
setprompt(int which)
{
    whichprompt = which;
    putprompt(getprompt(NULL));
}


/*
 * Code for dealing with input/output redirection.
 */

#define EMPTY -2                /* marks an unused slot in redirtab */
#ifndef PIPE_BUF
# define PIPESIZE 4096          /* amount of buffering in a pipe */
#else
# define PIPESIZE PIPE_BUF
#endif



/*
 * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
 * old file descriptors are stashed away so that the redirection can be
 * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
 * standard output, and the standard error if it becomes a duplicate of
 * stdout, is saved in memory.
 */

static void
redirect(redir, flags)
	union node *redir;
	int flags;
	{
	union node *n;
	struct redirtab *sv = NULL;
	int i;
	int fd;
	int newfd;
	int try;
	char memory[10];        /* file descriptors to write to memory */

	for (i = 10 ; --i >= 0 ; )
		memory[i] = 0;
	memory[1] = flags & REDIR_BACKQ;
	if (flags & REDIR_PUSH) {
		sv = ckmalloc(sizeof (struct redirtab));
		for (i = 0 ; i < 10 ; i++)
			sv->renamed[i] = EMPTY;
		sv->next = redirlist;
		redirlist = sv;
	}
	for (n = redir ; n ; n = n->nfile.next) {
		fd = n->nfile.fd;
		try = 0;
		if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
		    n->ndup.dupfd == fd)
			continue; /* redirect from/to same file descriptor */

		INTOFF;
		newfd = openredirect(n);
		if (((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) ||
		    (fd == fileno2)) {
			if (newfd == fd) {
				try++;
			} else if ((i = fcntl(fd, F_DUPFD, 10)) == -1) {
				switch (errno) {
				case EBADF:
					if (!try) {
						dupredirect(n, newfd, memory);
						try++;
						break;
					}
					/* FALLTHROUGH*/
				default:
					if (newfd >= 0) {
						close(newfd);
					}
					INTON;
					error("%d: %m", fd);
					/* NOTREACHED */
				}
			}
			if (!try) {
				close(fd);
				if (flags & REDIR_PUSH) {
					sv->renamed[fd] = i;
				}
				if (fd == fileno2) {
					fileno2 = i;
				}
			}
		} else if (fd != newfd) {
			close(fd);
		}
		if (fd == 0)
			fd0_redirected++;
		if (!try)
			dupredirect(n, newfd, memory);
		INTON;
	}
	if (memory[1])
		out1 = &memout;
	if (memory[2])
		out2 = &memout;
}


static int
openredirect(redir)
	union node *redir;
	{
	char *fname;
	int f;

	switch (redir->nfile.type) {
	case NFROM:
		fname = redir->nfile.expfname;
		if ((f = open(fname, O_RDONLY)) < 0)
			goto eopen;
		break;
	case NFROMTO:
		fname = redir->nfile.expfname;
		if ((f = open(fname, O_RDWR|O_CREAT|O_TRUNC, 0666)) < 0)
			goto ecreate;
		break;
	case NTO:
		/* Take care of noclobber mode. */
		if (Cflag) {
			fname = redir->nfile.expfname;
			if ((f = noclobberopen(fname)) < 0)
				goto ecreate;
			break;
		}
	case NTOOV:
		fname = redir->nfile.expfname;
#ifdef O_CREAT
		if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
			goto ecreate;
#else
		if ((f = creat(fname, 0666)) < 0)
			goto ecreate;
#endif
		break;
	case NAPPEND:
		fname = redir->nfile.expfname;
#ifdef O_APPEND
		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
			goto ecreate;
#else
		if ((f = open(fname, O_WRONLY)) < 0
		 && (f = creat(fname, 0666)) < 0)
			goto ecreate;
		lseek(f, (off_t)0, 2);
#endif
		break;
	default:
#ifdef DEBUG
		abort();
#endif
		/* Fall through to eliminate warning. */
	case NTOFD:
	case NFROMFD:
		f = -1;
		break;
	case NHERE:
	case NXHERE:
		f = openhere(redir);
		break;
	}

	return f;
ecreate:
	error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
eopen:
	error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
}


static void
dupredirect(union node *redir, int f, char memory[10])
{
	int fd = redir->nfile.fd;

	memory[fd] = 0;
	if (redir->nfile.type == NTOFD || redir->nfile.type == NFROMFD) {
		if (redir->ndup.dupfd >= 0) {   /* if not ">&-" */
			if (memory[redir->ndup.dupfd])
				memory[fd] = 1;
			else
				dup_as_newfd(redir->ndup.dupfd, fd);
		}
		return;
	}

	if (f != fd) {
		dup_as_newfd(f, fd);
		close(f);
	}
	return;
}


/*
 * Handle here documents.  Normally we fork off a process to write the
 * data to a pipe.  If the document is short, we can stuff the data in
 * the pipe without forking.
 */

static int
openhere(redir)
	union node *redir;
	{
	int pip[2];
	int len = 0;

	if (pipe(pip) < 0)
		error("Pipe call failed");
	if (redir->type == NHERE) {
		len = strlen(redir->nhere.doc->narg.text);
		if (len <= PIPESIZE) {
			xwrite(pip[1], redir->nhere.doc->narg.text, len);
			goto out;
		}
	}
	if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
		close(pip[0]);
		signal(SIGINT, SIG_IGN);
		signal(SIGQUIT, SIG_IGN);
		signal(SIGHUP, SIG_IGN);
#ifdef SIGTSTP
		signal(SIGTSTP, SIG_IGN);
#endif
		signal(SIGPIPE, SIG_DFL);
		if (redir->type == NHERE)
			xwrite(pip[1], redir->nhere.doc->narg.text, len);
		else
			expandhere(redir->nhere.doc, pip[1]);
		_exit(0);
	}
out:
	close(pip[1]);
	return pip[0];
}


/*
 * Undo the effects of the last redirection.
 */

static void
popredir(void)
{
	struct redirtab *rp = redirlist;
	int i;

	INTOFF;
	for (i = 0 ; i < 10 ; i++) {
		if (rp->renamed[i] != EMPTY) {
			if (i == 0)
				fd0_redirected--;
			close(i);
			if (rp->renamed[i] >= 0) {
				dup_as_newfd(rp->renamed[i], i);
				close(rp->renamed[i]);
			}
			if (rp->renamed[i] == fileno2) {
				fileno2 = i;
			}
		}
	}
	redirlist = rp->next;
	ckfree(rp);
	INTON;
}

/*
 * Discard all saved file descriptors.
 */

static void
clearredir(void) {
	struct redirtab *rp;
	int i;

	for (rp = redirlist ; rp ; rp = rp->next) {
		for (i = 0 ; i < 10 ; i++) {
			if (rp->renamed[i] >= 0) {
				close(rp->renamed[i]);
				if (rp->renamed[i] == fileno2) {
					fileno2 = -1;
				}
			}
			rp->renamed[i] = EMPTY;
		}
	}
	if (fileno2 != 2 && fileno2 >= 0) {
		close(fileno2);
		fileno2 = -1;
	}
}


/*
 * Copy a file descriptor to be >= to.  Returns -1
 * if the source file descriptor is closed, EMPTY if there are no unused
 * file descriptors left.
 */

static int
dup_as_newfd(from, to)
	int from;
	int to;
{
	int newfd;

	newfd = fcntl(from, F_DUPFD, to);
	if (newfd < 0) {
		if (errno == EMFILE)
			return EMPTY;
		else
			error("%d: %m", from);
	}
	return newfd;
}

/*
 * Open a file in noclobber mode.
 * The code was copied from bash.
 */
static int
noclobberopen(const char *fname)
{
	int r, fd;
	struct stat finfo, finfo2;

	/*
	 * If the file exists and is a regular file, return an error
	 * immediately.
	 */
	r = stat(fname, &finfo);
	if (r == 0 && S_ISREG(finfo.st_mode)) {
		errno = EEXIST;
		return -1;
	}

	/*
	 * If the file was not present (r != 0), make sure we open it
	 * exclusively so that if it is created before we open it, our open
	 * will fail.  Make sure that we do not truncate an existing file.
	 * Note that we don't turn on O_EXCL unless the stat failed -- if the
	 * file was not a regular file, we leave O_EXCL off.
	 */
	if (r != 0)
		return open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666);
	fd = open(fname, O_WRONLY|O_CREAT, 0666);

	/* If the open failed, return the file descriptor right away. */
	if (fd < 0)
		return fd;

	/*
	 * OK, the open succeeded, but the file may have been changed from a
	 * non-regular file to a regular file between the stat and the open.
	 * We are assuming that the O_EXCL open handles the case where FILENAME
	 * did not exist and is symlinked to an existing file between the stat
	 * and open.
	 */

	/*
	 * If we can open it and fstat the file descriptor, and neither check
	 * revealed that it was a regular file, and the file has not been
	 * replaced, return the file descriptor.
	 */
	 if (fstat(fd, &finfo2) == 0 && !S_ISREG(finfo2.st_mode) &&
	     finfo.st_dev == finfo2.st_dev && finfo.st_ino == finfo2.st_ino)
		return fd;

	/* The file has been replaced.  badness. */
	close(fd);
	errno = EEXIST;
	return -1;
}
/*#ifdef __weak_alias
__weak_alias(getmode,_getmode)
__weak_alias(setmode,_setmode)
#endif*/

#ifdef __GLIBC__
#define S_ISTXT __S_ISVTX
#endif

#define SET_LEN 6               /* initial # of bitcmd struct to malloc */
#define SET_LEN_INCR 4          /* # of bitcmd structs to add as needed */

typedef struct bitcmd {
	char    cmd;
	char    cmd2;
	mode_t  bits;
} BITCMD;

#define CMD2_CLR        0x01
#define CMD2_SET        0x02
#define CMD2_GBITS      0x04
#define CMD2_OBITS      0x08
#define CMD2_UBITS      0x10

static BITCMD   *addcmd (BITCMD *, int, int, int, u_int);
static void      compress_mode (BITCMD *);
#ifdef SETMODE_DEBUG
static void      dumpmode (BITCMD *);
#endif

/*
 * Given the old mode and an array of bitcmd structures, apply the operations
 * described in the bitcmd structures to the old mode, and return the new mode.
 * Note that there is no '=' command; a strict assignment is just a '-' (clear
 * bits) followed by a '+' (set bits).
 */
static mode_t
getmode(bbox, omode)
	const void *bbox;
	mode_t omode;
{
	const BITCMD *set;
	mode_t clrval, newmode, value;

	_DIAGASSERT(bbox != NULL);

	set = (const BITCMD *)bbox;
	newmode = omode;
	for (value = 0;; set++)
		switch(set->cmd) {
		/*
		 * When copying the user, group or other bits around, we "know"
		 * where the bits are in the mode so that we can do shifts to
		 * copy them around.  If we don't use shifts, it gets real
		 * grundgy with lots of single bit checks and bit sets.
		 */
		case 'u':
			value = (newmode & S_IRWXU) >> 6;
			goto common;

		case 'g':
			value = (newmode & S_IRWXG) >> 3;
			goto common;

		case 'o':
			value = newmode & S_IRWXO;
common:                 if (set->cmd2 & CMD2_CLR) {
				clrval =
				    (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
				if (set->cmd2 & CMD2_UBITS)
					newmode &= ~((clrval<<6) & set->bits);
				if (set->cmd2 & CMD2_GBITS)
					newmode &= ~((clrval<<3) & set->bits);
				if (set->cmd2 & CMD2_OBITS)
					newmode &= ~(clrval & set->bits);
			}
			if (set->cmd2 & CMD2_SET) {
				if (set->cmd2 & CMD2_UBITS)
					newmode |= (value<<6) & set->bits;
				if (set->cmd2 & CMD2_GBITS)
					newmode |= (value<<3) & set->bits;
				if (set->cmd2 & CMD2_OBITS)
					newmode |= value & set->bits;
			}
			break;

		case '+':
			newmode |= set->bits;
			break;

		case '-':
			newmode &= ~set->bits;
			break;

		case 'X':
			if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
				newmode |= set->bits;
			break;

		case '\0':
		default:
#ifdef SETMODE_DEBUG
			(void)printf("getmode:%04o -> %04o\n", omode, newmode);
#endif
			return (newmode);
		}
}

#define ADDCMD(a, b, c, d) do {                                         \
	if (set >= endset) {                                            \
		BITCMD *newset;                                         \
		setlen += SET_LEN_INCR;                                 \
		newset = realloc(saveset, sizeof(BITCMD) * setlen);     \
		if (newset == NULL) {                                   \
			free(saveset);                                  \
			return (NULL);                                  \
		}                                                       \
		set = newset + (set - saveset);                         \
		saveset = newset;                                       \
		endset = newset + (setlen - 2);                         \
	}                                                               \
	set = addcmd(set, (a), (b), (c), (d));                          \
} while (/*CONSTCOND*/0)

#define STANDARD_BITS   (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)

static void *
setmode(p)
	const char *p;
{
	int perm, who;
	char op, *ep;
	BITCMD *set, *saveset, *endset;
	sigset_t mysigset, sigoset;
	mode_t mask;
	int equalopdone = 0;    /* pacify gcc */
	int permXbits, setlen;

	if (!*p)
		return (NULL);

	/*
	 * Get a copy of the mask for the permissions that are mask relative.
	 * Flip the bits, we want what's not set.  Since it's possible that
	 * the caller is opening files inside a signal handler, protect them
	 * as best we can.
	 */
	sigfillset(&mysigset);
	(void)sigprocmask(SIG_BLOCK, &mysigset, &sigoset);
	(void)umask(mask = umask(0));
	mask = ~mask;
	(void)sigprocmask(SIG_SETMASK, &sigoset, NULL);

	setlen = SET_LEN + 2;

	if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
		return (NULL);
	saveset = set;
	endset = set + (setlen - 2);

	/*
	 * If an absolute number, get it and return; disallow non-octal digits
	 * or illegal bits.
	 */
	if (isdigit((unsigned char)*p)) {
		perm = (mode_t)strtol(p, &ep, 8);
		if (*ep || perm & ~(STANDARD_BITS|S_ISTXT)) {
			free(saveset);
			return (NULL);
		}
		ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
		set->cmd = 0;
		return (saveset);
	}

	/*
	 * Build list of structures to set/clear/copy bits as described by
	 * each clause of the symbolic mode.
	 */
	for (;;) {
		/* First, find out which bits might be modified. */
		for (who = 0;; ++p) {
			switch (*p) {
			case 'a':
				who |= STANDARD_BITS;
				break;
			case 'u':
				who |= S_ISUID|S_IRWXU;
				break;
			case 'g':
				who |= S_ISGID|S_IRWXG;
				break;
			case 'o':
				who |= S_IRWXO;
				break;
			default:
				goto getop;
			}
		}

getop:          if ((op = *p++) != '+' && op != '-' && op != '=') {
			free(saveset);
			return (NULL);
		}
		if (op == '=')
			equalopdone = 0;

		who &= ~S_ISTXT;
		for (perm = 0, permXbits = 0;; ++p) {
			switch (*p) {
			case 'r':
				perm |= S_IRUSR|S_IRGRP|S_IROTH;
				break;
			case 's':
				/*
				 * If specific bits where requested and
				 * only "other" bits ignore set-id.
				 */
				if (who == 0 || (who & ~S_IRWXO))
					perm |= S_ISUID|S_ISGID;
				break;
			case 't':
				/*
				 * If specific bits where requested and
				 * only "other" bits ignore set-id.
				 */
				if (who == 0 || (who & ~S_IRWXO)) {
					who |= S_ISTXT;
					perm |= S_ISTXT;
				}
				break;
			case 'w':
				perm |= S_IWUSR|S_IWGRP|S_IWOTH;
				break;
			case 'X':
				permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
				break;
			case 'x':
				perm |= S_IXUSR|S_IXGRP|S_IXOTH;
				break;
			case 'u':
			case 'g':
			case 'o':
				/*
				 * When ever we hit 'u', 'g', or 'o', we have
				 * to flush out any partial mode that we have,
				 * and then do the copying of the mode bits.
				 */
				if (perm) {
					ADDCMD(op, who, perm, mask);
					perm = 0;
				}
				if (op == '=')
					equalopdone = 1;
				if (op == '+' && permXbits) {
					ADDCMD('X', who, permXbits, mask);
					permXbits = 0;
				}
				ADDCMD(*p, who, op, mask);
				break;

			default:
				/*
				 * Add any permissions that we haven't already
				 * done.
				 */
				if (perm || (op == '=' && !equalopdone)) {
					if (op == '=')
						equalopdone = 1;
					ADDCMD(op, who, perm, mask);
					perm = 0;
				}
				if (permXbits) {
					ADDCMD('X', who, permXbits, mask);
					permXbits = 0;
				}
				goto apply;
			}
		}

apply:          if (!*p)
			break;
		if (*p != ',')
			goto getop;
		++p;
	}
	set->cmd = 0;
#ifdef SETMODE_DEBUG
	(void)printf("Before compress_mode()\n");
	dumpmode(saveset);
#endif
	compress_mode(saveset);
#ifdef SETMODE_DEBUG
	(void)printf("After compress_mode()\n");
	dumpmode(saveset);
#endif
	return (saveset);
}

static BITCMD *
addcmd(set, op, who, oparg, mask)
	BITCMD *set;
	int oparg, who;
	int op;
	u_int mask;
{

	_DIAGASSERT(set != NULL);

	switch (op) {
	case '=':
		set->cmd = '-';
		set->bits = who ? who : STANDARD_BITS;
		set++;

		op = '+';
		/* FALLTHROUGH */
	case '+':
	case '-':
	case 'X':
		set->cmd = op;
		set->bits = (who ? who : mask) & oparg;
		break;

	case 'u':
	case 'g':
	case 'o':
		set->cmd = op;
		if (who) {
			set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
				    ((who & S_IRGRP) ? CMD2_GBITS : 0) |
				    ((who & S_IROTH) ? CMD2_OBITS : 0);
			set->bits = (mode_t)~0;
		} else {
			set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
			set->bits = mask;
		}

		if (oparg == '+')
			set->cmd2 |= CMD2_SET;
		else if (oparg == '-')
			set->cmd2 |= CMD2_CLR;
		else if (oparg == '=')
			set->cmd2 |= CMD2_SET|CMD2_CLR;
		break;
	}
	return (set + 1);
}

#ifdef SETMODE_DEBUG
static void
dumpmode(set)
	BITCMD *set;
{

	_DIAGASSERT(set != NULL);

	for (; set->cmd; ++set)
		(void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
		    set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
		    set->cmd2 & CMD2_CLR ? " CLR" : "",
		    set->cmd2 & CMD2_SET ? " SET" : "",
		    set->cmd2 & CMD2_UBITS ? " UBITS" : "",
		    set->cmd2 & CMD2_GBITS ? " GBITS" : "",
		    set->cmd2 & CMD2_OBITS ? " OBITS" : "");
}
#endif

/*
 * Given an array of bitcmd structures, compress by compacting consecutive
 * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
 * 'g' and 'o' commands continue to be separate.  They could probably be
 * compacted, but it's not worth the effort.
 */
static void
compress_mode(set)
	BITCMD *set;
{
	BITCMD *nset;
	int setbits, clrbits, Xbits, op;

	_DIAGASSERT(set != NULL);

	for (nset = set;;) {
		/* Copy over any 'u', 'g' and 'o' commands. */
		while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
			*set++ = *nset++;
			if (!op)
				return;
		}

		for (setbits = clrbits = Xbits = 0;; nset++) {
			if ((op = nset->cmd) == '-') {
				clrbits |= nset->bits;
				setbits &= ~nset->bits;
				Xbits &= ~nset->bits;
			} else if (op == '+') {
				setbits |= nset->bits;
				clrbits &= ~nset->bits;
				Xbits &= ~nset->bits;
			} else if (op == 'X')
				Xbits |= nset->bits & ~setbits;
			else
				break;
		}
		if (clrbits) {
			set->cmd = '-';
			set->cmd2 = 0;
			set->bits = clrbits;
			set++;
		}
		if (setbits) {
			set->cmd = '+';
			set->cmd2 = 0;
			set->bits = setbits;
			set++;
		}
		if (Xbits) {
			set->cmd = 'X';
			set->cmd2 = 0;
			set->bits = Xbits;
			set++;
		}
	}
}
#ifdef DEBUG
static void shtree (union node *, int, char *, FILE*);
static void shcmd (union node *, FILE *);
static void sharg (union node *, FILE *);
static void indent (int, char *, FILE *);
static void trstring (char *);


static void
showtree(n)
	union node *n;
{
	trputs("showtree called\n");
	shtree(n, 1, NULL, stdout);
}


static void
shtree(n, ind, pfx, fp)
	union node *n;
	int ind;
	char *pfx;
	FILE *fp;
{
	struct nodelist *lp;
	const char *s;

	if (n == NULL)
		return;

	indent(ind, pfx, fp);
	switch(n->type) {
	case NSEMI:
		s = "; ";
		goto binop;
	case NAND:
		s = " && ";
		goto binop;
	case NOR:
		s = " || ";
binop:
		shtree(n->nbinary.ch1, ind, NULL, fp);
	   /*    if (ind < 0) */
			fputs(s, fp);
		shtree(n->nbinary.ch2, ind, NULL, fp);
		break;
	case NCMD:
		shcmd(n, fp);
		if (ind >= 0)
			putc('\n', fp);
		break;
	case NPIPE:
		for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
			shcmd(lp->n, fp);
			if (lp->next)
				fputs(" | ", fp);
		}
		if (n->npipe.backgnd)
			fputs(" &", fp);
		if (ind >= 0)
			putc('\n', fp);
		break;
	default:
		fprintf(fp, "<node type %d>", n->type);
		if (ind >= 0)
			putc('\n', fp);
		break;
	}
}



static void
shcmd(cmd, fp)
	union node *cmd;
	FILE *fp;
{
	union node *np;
	int first;
	const char *s;
	int dftfd;

	first = 1;
	for (np = cmd->ncmd.args ; np ; np = np->narg.next) {
		if (! first)
			putchar(' ');
		sharg(np, fp);
		first = 0;
	}
	for (np = cmd->ncmd.redirect ; np ; np = np->nfile.next) {
		if (! first)
			putchar(' ');
		switch (np->nfile.type) {
			case NTO:       s = ">";  dftfd = 1; break;
			case NAPPEND:   s = ">>"; dftfd = 1; break;
			case NTOFD:     s = ">&"; dftfd = 1; break;
			case NTOOV:     s = ">|"; dftfd = 1; break;
			case NFROM:     s = "<";  dftfd = 0; break;
			case NFROMFD:   s = "<&"; dftfd = 0; break;
			case NFROMTO:   s = "<>"; dftfd = 0; break;
			default:        s = "*error*"; dftfd = 0; break;
		}
		if (np->nfile.fd != dftfd)
			fprintf(fp, "%d", np->nfile.fd);
		fputs(s, fp);
		if (np->nfile.type == NTOFD || np->nfile.type == NFROMFD) {
			fprintf(fp, "%d", np->ndup.dupfd);
		} else {
			sharg(np->nfile.fname, fp);
		}
		first = 0;
	}
}



static void
sharg(arg, fp)
	union node *arg;
	FILE *fp;
	{
	char *p;
	struct nodelist *bqlist;
	int subtype;

	if (arg->type != NARG) {
		printf("<node type %d>\n", arg->type);
		fflush(stdout);
		abort();
	}
	bqlist = arg->narg.backquote;
	for (p = arg->narg.text ; *p ; p++) {
		switch (*p) {
		case CTLESC:
			putc(*++p, fp);
			break;
		case CTLVAR:
			putc('$', fp);
			putc('{', fp);
			subtype = *++p;
			if (subtype == VSLENGTH)
				putc('#', fp);

			while (*p != '=')
				putc(*p++, fp);

			if (subtype & VSNUL)
				putc(':', fp);

			switch (subtype & VSTYPE) {
			case VSNORMAL:
				putc('}', fp);
				break;
			case VSMINUS:
				putc('-', fp);
				break;
			case VSPLUS:
				putc('+', fp);
				break;
			case VSQUESTION:
				putc('?', fp);
				break;
			case VSASSIGN:
				putc('=', fp);
				break;
			case VSTRIMLEFT:
				putc('#', fp);
				break;
			case VSTRIMLEFTMAX:
				putc('#', fp);
				putc('#', fp);
				break;
			case VSTRIMRIGHT:
				putc('%', fp);
				break;
			case VSTRIMRIGHTMAX:
				putc('%', fp);
				putc('%', fp);
				break;
			case VSLENGTH:
				break;
			default:
				printf("<subtype %d>", subtype);
			}
			break;
		case CTLENDVAR:
		     putc('}', fp);
		     break;
		case CTLBACKQ:
		case CTLBACKQ|CTLQUOTE:
			putc('$', fp);
			putc('(', fp);
			shtree(bqlist->n, -1, NULL, fp);
			putc(')', fp);
			break;
		default:
			putc(*p, fp);
			break;
		}
	}
}


static void
indent(amount, pfx, fp)
	int amount;
	char *pfx;
	FILE *fp;
{
	int i;

	for (i = 0 ; i < amount ; i++) {
		if (pfx && i == amount - 1)
			fputs(pfx, fp);
		putc('\t', fp);
	}
}
#endif



/*
 * Debugging stuff.
 */


#ifdef DEBUG
FILE *tracefile;

#if DEBUG == 2
static int debug = 1;
#else
static int debug = 0;
#endif


static void
trputc(c)
	int c;
{
	if (tracefile == NULL)
		return;
	putc(c, tracefile);
	if (c == '\n')
		fflush(tracefile);
}

static void
trace(const char *fmt, ...)
{
	va_list va;
#ifdef __STDC__
	va_start(va, fmt);
#else
	char *fmt;
	va_start(va);
	fmt = va_arg(va, char *);
#endif
	if (tracefile != NULL) {
		(void) vfprintf(tracefile, fmt, va);
		if (strchr(fmt, '\n'))
			(void) fflush(tracefile);
	}
	va_end(va);
}


static void
trputs(s)
	const char *s;
{
	if (tracefile == NULL)
		return;
	fputs(s, tracefile);
	if (strchr(s, '\n'))
		fflush(tracefile);
}


static void
trstring(s)
	char *s;
{
	char *p;
	char c;

	if (tracefile == NULL)
		return;
	putc('"', tracefile);
	for (p = s ; *p ; p++) {
		switch (*p) {
		case '\n':  c = 'n';  goto backslash;
		case '\t':  c = 't';  goto backslash;
		case '\r':  c = 'r';  goto backslash;
		case '"':  c = '"';  goto backslash;
		case '\\':  c = '\\';  goto backslash;
		case CTLESC:  c = 'e';  goto backslash;
		case CTLVAR:  c = 'v';  goto backslash;
		case CTLVAR+CTLQUOTE:  c = 'V';  goto backslash;
		case CTLBACKQ:  c = 'q';  goto backslash;
		case CTLBACKQ+CTLQUOTE:  c = 'Q';  goto backslash;
backslash:        putc('\\', tracefile);
			putc(c, tracefile);
			break;
		default:
			if (*p >= ' ' && *p <= '~')
				putc(*p, tracefile);
			else {
				putc('\\', tracefile);
				putc(*p >> 6 & 03, tracefile);
				putc(*p >> 3 & 07, tracefile);
				putc(*p & 07, tracefile);
			}
			break;
		}
	}
	putc('"', tracefile);
}


static void
trargs(ap)
	char **ap;
{
	if (tracefile == NULL)
		return;
	while (*ap) {
		trstring(*ap++);
		if (*ap)
			putc(' ', tracefile);
		else
			putc('\n', tracefile);
	}
	fflush(tracefile);
}


static void
opentrace() {
	char s[100];
#ifdef O_APPEND
	int flags;
#endif

	if (!debug)
		return;
#ifdef not_this_way
	{
		char *p;
		if ((p = getenv("HOME")) == NULL) {
			if (geteuid() == 0)
				p = "/";
			else
				p = "/tmp";
		}
		strcpy(s, p);
		strcat(s, "/trace");
	}
#else
	strcpy(s, "./trace");
#endif /* not_this_way */
	if ((tracefile = fopen(s, "a")) == NULL) {
		fprintf(stderr, "Can't open %s\n", s);
		return;
	}
#ifdef O_APPEND
	if ((flags = fcntl(fileno(tracefile), F_GETFL, 0)) >= 0)
		fcntl(fileno(tracefile), F_SETFL, flags | O_APPEND);
#endif
	fputs("\nTracing started.\n", tracefile);
	fflush(tracefile);
}
#endif /* DEBUG */


/*
 * The trap builtin.
 */

static int
trapcmd(argc, argv)
	int argc;
	char **argv;
{
	char *action;
	char **ap;
	int signo;

	if (argc <= 1) {
		for (signo = 0 ; signo < NSIG ; signo++) {
			if (trap[signo] != NULL) {
				char *p;

				p = single_quote(trap[signo]);
				out1fmt("trap -- %s %s\n", p,
					signal_names[signo] + (signo ? 3 : 0)
				);
				stunalloc(p);
			}
		}
		return 0;
	}
	ap = argv + 1;
	if (argc == 2)
		action = NULL;
	else
		action = *ap++;
	while (*ap) {
		if ((signo = decode_signal(*ap, 0)) < 0)
			error("%s: bad trap", *ap);
		INTOFF;
		if (action) {
			if (action[0] == '-' && action[1] == '\0')
				action = NULL;
			else
				action = savestr(action);
		}
		if (trap[signo])
			ckfree(trap[signo]);
		trap[signo] = action;
		if (signo != 0)
			setsignal(signo);
		INTON;
		ap++;
	}
	return 0;
}






/*
 * Set the signal handler for the specified signal.  The routine figures
 * out what it should be set to.
 */

static void
setsignal(int signo)
{
	int action;
	char *t;
	struct sigaction act;

	if ((t = trap[signo]) == NULL)
		action = S_DFL;
	else if (*t != '\0')
		action = S_CATCH;
	else
		action = S_IGN;
	if (rootshell && action == S_DFL) {
		switch (signo) {
		case SIGINT:
			if (iflag || minusc || sflag == 0)
				action = S_CATCH;
			break;
		case SIGQUIT:
#ifdef DEBUG
			{

			if (debug)
				break;
			}
#endif
			/* FALLTHROUGH */
		case SIGTERM:
			if (iflag)
				action = S_IGN;
			break;
#ifdef JOBS
		case SIGTSTP:
		case SIGTTOU:
			if (mflag)
				action = S_IGN;
			break;
#endif
		}
	}

	t = &sigmode[signo - 1];
	if (*t == 0) {
		/*
		 * current setting unknown
		 */
		if (sigaction(signo, 0, &act) == -1) {
			/*
			 * Pretend it worked; maybe we should give a warning
			 * here, but other shells don't. We don't alter
			 * sigmode, so that we retry every time.
			 */
			return;
		}
		if (act.sa_handler == SIG_IGN) {
			if (mflag && (signo == SIGTSTP ||
			     signo == SIGTTIN || signo == SIGTTOU)) {
				*t = S_IGN;     /* don't hard ignore these */
			} else
				*t = S_HARD_IGN;
		} else {
			*t = S_RESET;   /* force to be set */
		}
	}
	if (*t == S_HARD_IGN || *t == action)
		return;
	switch (action) {
	case S_CATCH:
		act.sa_handler = onsig;
		break;
	case S_IGN:
		act.sa_handler = SIG_IGN;
		break;
	default:
		act.sa_handler = SIG_DFL;
	}
	*t = action;
	act.sa_flags = 0;
	sigemptyset(&act.sa_mask);
	sigaction(signo, &act, 0);
}

/*
 * Ignore a signal.
 */

static void
ignoresig(signo)
	int signo;
{
	if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) {
		signal(signo, SIG_IGN);
	}
	sigmode[signo - 1] = S_HARD_IGN;
}


/*
 * Signal handler.
 */

static void
onsig(int signo)
{
	if (signo == SIGINT && trap[SIGINT] == NULL) {
		onint();
		return;
	}
	gotsig[signo - 1] = 1;
	pendingsigs++;
}


/*
 * Called to execute a trap.  Perhaps we should avoid entering new trap
 * handlers while we are executing a trap handler.
 */

static void
dotrap(void)
{
	int i;
	int savestatus;

	for (;;) {
		for (i = 1 ; ; i++) {
			if (gotsig[i - 1])
				break;
			if (i >= NSIG - 1)
				goto done;
		}
		gotsig[i - 1] = 0;
		savestatus=exitstatus;
		evalstring(trap[i], 0);
		exitstatus=savestatus;
	}
done:
	pendingsigs = 0;
}

/*
 * Called to exit the shell.
 */

static void
exitshell(int status)
{
	struct jmploc loc1, loc2;
	char *p;

	TRACE(("exitshell(%d) pid=%d\n", status, getpid()));
	if (setjmp(loc1.loc)) {
		goto l1;
	}
	if (setjmp(loc2.loc)) {
		goto l2;
	}
	handler = &loc1;
	if ((p = trap[0]) != NULL && *p != '\0') {
		trap[0] = NULL;
		evalstring(p, 0);
	}
l1:   handler = &loc2;                  /* probably unnecessary */
	flushall();
#ifdef JOBS
	setjobctl(0);
#endif
l2:   _exit(status);
	/* NOTREACHED */
}

static int decode_signal(const char *string, int minsig)
{
	int signo;

	if (is_number(string, &signo)) {
		if (signo >= NSIG) {
			return -1;
		}
		return signo;
	}

	signo = minsig;
	if (!signo) {
		goto zero;
	}
	for (; signo < NSIG; signo++) {
		if (!strcasecmp(string, &(signal_names[signo])[3])) {
			return signo;
		}
zero:
		if (!strcasecmp(string, signal_names[signo])) {
			return signo;
		}
	}

	return -1;
}
static struct var **hashvar (const char *);
static void showvars (const char *, int, int);
static struct var **findvar (struct var **, const char *);

/*
 * Initialize the varable symbol tables and import the environment
 */

/*
 * This routine initializes the builtin variables.  It is called when the
 * shell is initialized and again when a shell procedure is spawned.
 */

static void
initvar() {
	const struct varinit *ip;
	struct var *vp;
	struct var **vpp;

	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
		if ((vp->flags & VEXPORT) == 0) {
			vpp = hashvar(ip->text);
			vp->next = *vpp;
			*vpp = vp;
			vp->text = strdup(ip->text);
			vp->flags = ip->flags;
			vp->func = ip->func;
		}
	}
	/*
	 * PS1 depends on uid
	 */
	if ((vps1.flags & VEXPORT) == 0) {
		vpp = hashvar("PS1=");
		vps1.next = *vpp;
		*vpp = &vps1;
		vps1.text = strdup(geteuid() ? "PS1=$ " : "PS1=# ");
		vps1.flags = VSTRFIXED|VTEXTFIXED;
	}
}

/*
 * Set the value of a variable.  The flags argument is ored with the
 * flags of the variable.  If val is NULL, the variable is unset.
 */

static void
setvar(name, val, flags)
	const char *name, *val;
	int flags;
{
	const char *p;
	int len;
	int namelen;
	char *nameeq;
	int isbad;
	int vallen = 0;

	isbad = 0;
	p = name;
	if (! is_name(*p))
		isbad = 1;
	p++;
	for (;;) {
		if (! is_in_name(*p)) {
			if (*p == '\0' || *p == '=')
				break;
			isbad = 1;
		}
		p++;
	}
	namelen = p - name;
	if (isbad)
		error("%.*s: bad variable name", namelen, name);
	len = namelen + 2;              /* 2 is space for '=' and '\0' */
	if (val == NULL) {
		flags |= VUNSET;
	} else {
		len += vallen = strlen(val);
	}
	INTOFF;
	nameeq = ckmalloc(len);
	memcpy(nameeq, name, namelen);
	nameeq[namelen] = '=';
	if (val) {
		memcpy(nameeq + namelen + 1, val, vallen + 1);
	} else {
		nameeq[namelen + 1] = '\0';
	}
	setvareq(nameeq, flags);
	INTON;
}



/*
 * Same as setvar except that the variable and value are passed in
 * the first argument as name=value.  Since the first argument will
 * be actually stored in the table, it should not be a string that
 * will go away.
 */

static void
setvareq(s, flags)
	char *s;
	int flags;
{
	struct var *vp, **vpp;

	vpp = hashvar(s);
	flags |= (VEXPORT & (((unsigned) (1 - aflag)) - 1));
	if ((vp = *findvar(vpp, s))) {
		if (vp->flags & VREADONLY) {
			size_t len = strchr(s, '=') - s;
			error("%.*s: is read only", len, s);
		}
		INTOFF;

		if (vp->func && (flags & VNOFUNC) == 0)
			(*vp->func)(strchr(s, '=') + 1);

		if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
			ckfree(vp->text);

		vp->flags &= ~(VTEXTFIXED|VSTACK|VUNSET);
		vp->flags |= flags;
		vp->text = s;

		/*
		 * We could roll this to a function, to handle it as
		 * a regular variable function callback, but why bother?
		 */
		if (iflag && (vp == &vmpath || (vp == &vmail && !mpathset())))
			chkmail(1);
		INTON;
		return;
	}
	/* not found */
	vp = ckmalloc(sizeof (*vp));
	vp->flags = flags;
	vp->text = s;
	vp->next = *vpp;
	vp->func = NULL;
	*vpp = vp;
}



/*
 * Process a linked list of variable assignments.
 */

static void
listsetvar(mylist)
	struct strlist *mylist;
	{
	struct strlist *lp;

	INTOFF;
	for (lp = mylist ; lp ; lp = lp->next) {
		setvareq(savestr(lp->text), 0);
	}
	INTON;
}



/*
 * Find the value of a variable.  Returns NULL if not set.
 */

static char *
lookupvar(name)
	const char *name;
	{
	struct var *v;

	if ((v = *findvar(hashvar(name), name)) && !(v->flags & VUNSET)) {
		return strchr(v->text, '=') + 1;
	}
	return NULL;
}



/*
 * Search the environment of a builtin command.
 */

static char *
bltinlookup(name)
	const char *name;
{
	struct strlist *sp;

	for (sp = cmdenviron ; sp ; sp = sp->next) {
		if (varequal(sp->text, name))
			return strchr(sp->text, '=') + 1;
	}
	return lookupvar(name);
}



/*
 * Generate a list of exported variables.  This routine is used to construct
 * the third argument to execve when executing a program.
 */

static char **
environment() {
	int nenv;
	struct var **vpp;
	struct var *vp;
	char **env;
	char **ep;

	nenv = 0;
	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
		for (vp = *vpp ; vp ; vp = vp->next)
			if (vp->flags & VEXPORT)
				nenv++;
	}
	ep = env = stalloc((nenv + 1) * sizeof *env);
	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
		for (vp = *vpp ; vp ; vp = vp->next)
			if (vp->flags & VEXPORT)
				*ep++ = vp->text;
	}
	*ep = NULL;
	return env;
}


/*
 * Called when a shell procedure is invoked to clear out nonexported
 * variables.  It is also necessary to reallocate variables of with
 * VSTACK set since these are currently allocated on the stack.
 */

static void
shprocvar(void) {
	struct var **vpp;
	struct var *vp, **prev;

	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
		for (prev = vpp ; (vp = *prev) != NULL ; ) {
			if ((vp->flags & VEXPORT) == 0) {
				*prev = vp->next;
				if ((vp->flags & VTEXTFIXED) == 0)
					ckfree(vp->text);
				if ((vp->flags & VSTRFIXED) == 0)
					ckfree(vp);
			} else {
				if (vp->flags & VSTACK) {
					vp->text = savestr(vp->text);
					vp->flags &=~ VSTACK;
				}
				prev = &vp->next;
			}
		}
	}
	initvar();
}



/*
 * Command to list all variables which are set.  Currently this command
 * is invoked from the set command when the set command is called without
 * any variables.
 */

static int
showvarscmd(argc, argv)
	int argc;
	char **argv;
{
	showvars(nullstr, VUNSET, VUNSET);
	return 0;
}



/*
 * The export and readonly commands.
 */

static int
exportcmd(argc, argv)
	int argc;
	char **argv;
{
	struct var *vp;
	char *name;
	const char *p;
	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
	int pflag;

	listsetvar(cmdenviron);
	pflag = (nextopt("p") == 'p');
	if (argc > 1 && !pflag) {
		while ((name = *argptr++) != NULL) {
			if ((p = strchr(name, '=')) != NULL) {
				p++;
			} else {
				if ((vp = *findvar(hashvar(name), name))) {
					vp->flags |= flag;
					goto found;
				}
			}
			setvar(name, p, flag);
found:;
		}
	} else {
		showvars(argv[0], flag, 0);
	}
	return 0;
}


/*
 * The "local" command.
 */

/* funcnest nonzero if we are currently evaluating a function */

static int
localcmd(argc, argv)
	int argc;
	char **argv;
{
	char *name;

	if (! funcnest)
		error("Not in a function");
	while ((name = *argptr++) != NULL) {
		mklocal(name);
	}
	return 0;
}


/*
 * Make a variable a local variable.  When a variable is made local, it's
 * value and flags are saved in a localvar structure.  The saved values
 * will be restored when the shell function returns.  We handle the name
 * "-" as a special case.
 */

static void
mklocal(name)
	char *name;
	{
	struct localvar *lvp;
	struct var **vpp;
	struct var *vp;

	INTOFF;
	lvp = ckmalloc(sizeof (struct localvar));
	if (name[0] == '-' && name[1] == '\0') {
		char *p;
		p = ckmalloc(sizeof optet_vals);
		lvp->text = memcpy(p, optet_vals, sizeof optet_vals);
		vp = NULL;
	} else {
		vpp = hashvar(name);
		vp = *findvar(vpp, name);
		if (vp == NULL) {
			if (strchr(name, '='))
				setvareq(savestr(name), VSTRFIXED);
			else
				setvar(name, NULL, VSTRFIXED);
			vp = *vpp;      /* the new variable */
			lvp->text = NULL;
			lvp->flags = VUNSET;
		} else {
			lvp->text = vp->text;
			lvp->flags = vp->flags;
			vp->flags |= VSTRFIXED|VTEXTFIXED;
			if (strchr(name, '='))
				setvareq(savestr(name), 0);
		}
	}
	lvp->vp = vp;
	lvp->next = localvars;
	localvars = lvp;
	INTON;
}


/*
 * Called after a function returns.
 */

static void
poplocalvars() {
	struct localvar *lvp;
	struct var *vp;

	while ((lvp = localvars) != NULL) {
		localvars = lvp->next;
		vp = lvp->vp;
		if (vp == NULL) {       /* $- saved */
			memcpy(optet_vals, lvp->text, sizeof optet_vals);
			ckfree(lvp->text);
		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
			(void)unsetvar(vp->text);
		} else {
			if ((vp->flags & VTEXTFIXED) == 0)
				ckfree(vp->text);
			vp->flags = lvp->flags;
			vp->text = lvp->text;
		}
		ckfree(lvp);
	}
}


static int
setvarcmd(argc, argv)
	int argc;
	char **argv;
{
	if (argc <= 2)
		return unsetcmd(argc, argv);
	else if (argc == 3)
		setvar(argv[1], argv[2], 0);
	else
		error("List assignment not implemented");
	return 0;
}


/*
 * The unset builtin command.  We unset the function before we unset the
 * variable to allow a function to be unset when there is a readonly variable
 * with the same name.
 */

static int
unsetcmd(argc, argv)
	int argc;
	char **argv;
{
	char **ap;
	int i;
	int flg_func = 0;
	int flg_var = 0;
	int ret = 0;

	while ((i = nextopt("vf")) != '\0') {
		if (i == 'f')
			flg_func = 1;
		else
			flg_var = 1;
	}
	if (flg_func == 0 && flg_var == 0)
		flg_var = 1;

	for (ap = argptr; *ap ; ap++) {
		if (flg_func)
			unsetfunc(*ap);
		if (flg_var)
			ret |= unsetvar(*ap);
	}
	return ret;
}


/*
 * Unset the specified variable.
 */

static int
unsetvar(s)
	const char *s;
	{
	struct var **vpp;
	struct var *vp;

	vpp = findvar(hashvar(s), s);
	vp = *vpp;
	if (vp) {
		if (vp->flags & VREADONLY)
			return (1);
		INTOFF;
		if (*(strchr(vp->text, '=') + 1) != '\0')
			setvar(s, nullstr, 0);
		vp->flags &= ~VEXPORT;
		vp->flags |= VUNSET;
		if ((vp->flags & VSTRFIXED) == 0) {
			if ((vp->flags & VTEXTFIXED) == 0)
				ckfree(vp->text);
			*vpp = vp->next;
			ckfree(vp);
		}
		INTON;
		return (0);
	}

	return (0);
}



/*
 * Find the appropriate entry in the hash table from the name.
 */

static struct var **
hashvar(p)
	const char *p;
	{
	unsigned int hashval;

	hashval = ((unsigned char) *p) << 4;
	while (*p && *p != '=')
		hashval += (unsigned char) *p++;
	return &vartab[hashval % VTABSIZE];
}



/*
 * Returns true if the two strings specify the same varable.  The first
 * variable name is terminated by '='; the second may be terminated by
 * either '=' or '\0'.
 */

static int
varequal(p, q)
	const char *p, *q;
	{
	while (*p == *q++) {
		if (*p++ == '=')
			return 1;
	}
	if (*p == '=' && *(q - 1) == '\0')
		return 1;
	return 0;
}

static void
showvars(const char *myprefix, int mask, int xor)
{
	struct var **vpp;
	struct var *vp;
	const char *sep = myprefix == nullstr ? myprefix : spcstr;

	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
		for (vp = *vpp ; vp ; vp = vp->next) {
			if ((vp->flags & mask) ^ xor) {
				char *p;
				int len;

				p = strchr(vp->text, '=') + 1;
				len = p - vp->text;
				p = single_quote(p);

				out1fmt(
					"%s%s%.*s%s\n", myprefix, sep, len,
					vp->text, p
				);
				stunalloc(p);
			}
		}
	}
}

static struct var **
findvar(struct var **vpp, const char *name)
{
	for (; *vpp; vpp = &(*vpp)->next) {
		if (varequal((*vpp)->text, name)) {
			break;
		}
	}
	return vpp;
}

/*
 * Copyright (c) 1999 Herbert Xu <herbert@debian.org>
 * This file contains code for the times builtin.
 * $Id: ash.c,v 1.4 2001/07/02 17:27:21 andersen Exp $
 */
static int timescmd (int argc, char **argv)
{
	struct tms buf;
	long int clk_tck = sysconf(_SC_CLK_TCK);

	times(&buf);
	printf("%dm%fs %dm%fs\n%dm%fs %dm%fs\n",
	       (int) (buf.tms_utime / clk_tck / 60),
	       ((double) buf.tms_utime) / clk_tck,
	       (int) (buf.tms_stime / clk_tck / 60),
	       ((double) buf.tms_stime) / clk_tck,
	       (int) (buf.tms_cutime / clk_tck / 60),
	       ((double) buf.tms_cutime) / clk_tck,
	       (int) (buf.tms_cstime / clk_tck / 60),
	       ((double) buf.tms_cstime) / clk_tck);
	return 0;
}


/*-
 * Copyright (c) 1989, 1991, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. <BSD Advertising Clause omitted per the July 22, 1999 licensing change
 *              ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change>
 *
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */