/* vi: set sw=4 ts=4: */
/*
 * awk implementation for busybox
 *
 * Copyright (C) 2002 by Dmitry Zakharov <dmit@crp.bank.gov.ua>
 *
 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
 */

#include "libbb.h"
#include "xregex.h"
#include <math.h>

/* This is a NOEXEC applet. Be very careful! */


#define	MAXVARFMT       240
#define	MINNVBLOCK      64

/* variable flags */
#define	VF_NUMBER       0x0001	/* 1 = primary type is number */
#define	VF_ARRAY        0x0002	/* 1 = it's an array */

#define	VF_CACHED       0x0100	/* 1 = num/str value has cached str/num eq */
#define	VF_USER         0x0200	/* 1 = user input (may be numeric string) */
#define	VF_SPECIAL      0x0400	/* 1 = requires extra handling when changed */
#define	VF_WALK         0x0800	/* 1 = variable has alloc'd x.walker list */
#define	VF_FSTR         0x1000	/* 1 = var::string points to fstring buffer */
#define	VF_CHILD        0x2000	/* 1 = function arg; x.parent points to source */
#define	VF_DIRTY        0x4000	/* 1 = variable was set explicitly */

/* these flags are static, don't change them when value is changed */
#define	VF_DONTTOUCH    (VF_ARRAY | VF_SPECIAL | VF_WALK | VF_CHILD | VF_DIRTY)

/* Variable */
typedef struct var_s {
	unsigned type;            /* flags */
	double number;
	char *string;
	union {
		int aidx;               /* func arg idx (for compilation stage) */
		struct xhash_s *array;  /* array ptr */
		struct var_s *parent;   /* for func args, ptr to actual parameter */
		char **walker;          /* list of array elements (for..in) */
	} x;
} var;

/* Node chain (pattern-action chain, BEGIN, END, function bodies) */
typedef struct chain_s {
	struct node_s *first;
	struct node_s *last;
	const char *programname;
} chain;

/* Function */
typedef struct func_s {
	unsigned nargs;
	struct chain_s body;
} func;

/* I/O stream */
typedef struct rstream_s {
	FILE *F;
	char *buffer;
	int adv;
	int size;
	int pos;
	smallint is_pipe;
} rstream;

typedef struct hash_item_s {
	union {
		struct var_s v;         /* variable/array hash */
		struct rstream_s rs;    /* redirect streams hash */
		struct func_s f;        /* functions hash */
	} data;
	struct hash_item_s *next;       /* next in chain */
	char name[1];                   /* really it's longer */
} hash_item;

typedef struct xhash_s {
	unsigned nel;           /* num of elements */
	unsigned csize;         /* current hash size */
	unsigned nprime;        /* next hash size in PRIMES[] */
	unsigned glen;          /* summary length of item names */
	struct hash_item_s **items;
} xhash;

/* Tree node */
typedef struct node_s {
	uint32_t info;
	unsigned lineno;
	union {
		struct node_s *n;
		var *v;
		int i;
		char *s;
		regex_t *re;
	} l;
	union {
		struct node_s *n;
		regex_t *ire;
		func *f;
		int argno;
	} r;
	union {
		struct node_s *n;
	} a;
} node;

/* Block of temporary variables */
typedef struct nvblock_s {
	int size;
	var *pos;
	struct nvblock_s *prev;
	struct nvblock_s *next;
	var nv[];
} nvblock;

typedef struct tsplitter_s {
	node n;
	regex_t re[2];
} tsplitter;

/* simple token classes */
/* Order and hex values are very important!!!  See next_token() */
#define	TC_SEQSTART	 1				/* ( */
#define	TC_SEQTERM	(1 << 1)		/* ) */
#define	TC_REGEXP	(1 << 2)		/* /.../ */
#define	TC_OUTRDR	(1 << 3)		/* | > >> */
#define	TC_UOPPOST	(1 << 4)		/* unary postfix operator */
#define	TC_UOPPRE1	(1 << 5)		/* unary prefix operator */
#define	TC_BINOPX	(1 << 6)		/* two-opnd operator */
#define	TC_IN		(1 << 7)
#define	TC_COMMA	(1 << 8)
#define	TC_PIPE		(1 << 9)		/* input redirection pipe */
#define	TC_UOPPRE2	(1 << 10)		/* unary prefix operator */
#define	TC_ARRTERM	(1 << 11)		/* ] */
#define	TC_GRPSTART	(1 << 12)		/* { */
#define	TC_GRPTERM	(1 << 13)		/* } */
#define	TC_SEMICOL	(1 << 14)
#define	TC_NEWLINE	(1 << 15)
#define	TC_STATX	(1 << 16)		/* ctl statement (for, next...) */
#define	TC_WHILE	(1 << 17)
#define	TC_ELSE		(1 << 18)
#define	TC_BUILTIN	(1 << 19)
#define	TC_GETLINE	(1 << 20)
#define	TC_FUNCDECL	(1 << 21)		/* `function' `func' */
#define	TC_BEGIN	(1 << 22)
#define	TC_END		(1 << 23)
#define	TC_EOF		(1 << 24)
#define	TC_VARIABLE	(1 << 25)
#define	TC_ARRAY	(1 << 26)
#define	TC_FUNCTION	(1 << 27)
#define	TC_STRING	(1 << 28)
#define	TC_NUMBER	(1 << 29)

#define	TC_UOPPRE  (TC_UOPPRE1 | TC_UOPPRE2)

/* combined token classes */
#define	TC_BINOP   (TC_BINOPX | TC_COMMA | TC_PIPE | TC_IN)
#define	TC_UNARYOP (TC_UOPPRE | TC_UOPPOST)
#define	TC_OPERAND (TC_VARIABLE | TC_ARRAY | TC_FUNCTION \
                   | TC_BUILTIN | TC_GETLINE | TC_SEQSTART | TC_STRING | TC_NUMBER)

#define	TC_STATEMNT (TC_STATX | TC_WHILE)
#define	TC_OPTERM  (TC_SEMICOL | TC_NEWLINE)

/* word tokens, cannot mean something else if not expected */
#define	TC_WORD    (TC_IN | TC_STATEMNT | TC_ELSE | TC_BUILTIN \
                   | TC_GETLINE | TC_FUNCDECL | TC_BEGIN | TC_END)

/* discard newlines after these */
#define	TC_NOTERM  (TC_COMMA | TC_GRPSTART | TC_GRPTERM \
                   | TC_BINOP | TC_OPTERM)

/* what can expression begin with */
#define	TC_OPSEQ   (TC_OPERAND | TC_UOPPRE | TC_REGEXP)
/* what can group begin with */
#define	TC_GRPSEQ  (TC_OPSEQ | TC_OPTERM | TC_STATEMNT | TC_GRPSTART)

/* if previous token class is CONCAT1 and next is CONCAT2, concatenation */
/* operator is inserted between them */
#define	TC_CONCAT1 (TC_VARIABLE | TC_ARRTERM | TC_SEQTERM \
                   | TC_STRING | TC_NUMBER | TC_UOPPOST)
#define	TC_CONCAT2 (TC_OPERAND | TC_UOPPRE)

#define	OF_RES1    0x010000
#define	OF_RES2    0x020000
#define	OF_STR1    0x040000
#define	OF_STR2    0x080000
#define	OF_NUM1    0x100000
#define	OF_CHECKED 0x200000

/* combined operator flags */
#define	xx	0
#define	xV	OF_RES2
#define	xS	(OF_RES2 | OF_STR2)
#define	Vx	OF_RES1
#define	VV	(OF_RES1 | OF_RES2)
#define	Nx	(OF_RES1 | OF_NUM1)
#define	NV	(OF_RES1 | OF_NUM1 | OF_RES2)
#define	Sx	(OF_RES1 | OF_STR1)
#define	SV	(OF_RES1 | OF_STR1 | OF_RES2)
#define	SS	(OF_RES1 | OF_STR1 | OF_RES2 | OF_STR2)

#define	OPCLSMASK 0xFF00
#define	OPNMASK   0x007F

/* operator priority is a highest byte (even: r->l, odd: l->r grouping)
 * For builtins it has different meaning: n n s3 s2 s1 v3 v2 v1,
 * n - min. number of args, vN - resolve Nth arg to var, sN - resolve to string
 */
#define P(x)      (x << 24)
#define PRIMASK   0x7F000000
#define PRIMASK2  0x7E000000

/* Operation classes */

#define	SHIFT_TIL_THIS	0x0600
#define	RECUR_FROM_THIS	0x1000

enum {
	OC_DELETE = 0x0100,     OC_EXEC = 0x0200,       OC_NEWSOURCE = 0x0300,
	OC_PRINT = 0x0400,      OC_PRINTF = 0x0500,     OC_WALKINIT = 0x0600,

	OC_BR = 0x0700,         OC_BREAK = 0x0800,      OC_CONTINUE = 0x0900,
	OC_EXIT = 0x0a00,       OC_NEXT = 0x0b00,       OC_NEXTFILE = 0x0c00,
	OC_TEST = 0x0d00,       OC_WALKNEXT = 0x0e00,

	OC_BINARY = 0x1000,     OC_BUILTIN = 0x1100,    OC_COLON = 0x1200,
	OC_COMMA = 0x1300,      OC_COMPARE = 0x1400,    OC_CONCAT = 0x1500,
	OC_FBLTIN = 0x1600,     OC_FIELD = 0x1700,      OC_FNARG = 0x1800,
	OC_FUNC = 0x1900,       OC_GETLINE = 0x1a00,    OC_IN = 0x1b00,
	OC_LAND = 0x1c00,       OC_LOR = 0x1d00,        OC_MATCH = 0x1e00,
	OC_MOVE = 0x1f00,       OC_PGETLINE = 0x2000,   OC_REGEXP = 0x2100,
	OC_REPLACE = 0x2200,    OC_RETURN = 0x2300,     OC_SPRINTF = 0x2400,
	OC_TERNARY = 0x2500,    OC_UNARY = 0x2600,      OC_VAR = 0x2700,
	OC_DONE = 0x2800,

	ST_IF = 0x3000,         ST_DO = 0x3100,         ST_FOR = 0x3200,
	ST_WHILE = 0x3300
};

/* simple builtins */
enum {
	F_in,	F_rn,	F_co,	F_ex,	F_lg,	F_si,	F_sq,	F_sr,
	F_ti,	F_le,	F_sy,	F_ff,	F_cl
};

/* builtins */
enum {
	B_a2,	B_ix,	B_ma,	B_sp,	B_ss,	B_ti,   B_mt,	B_lo,	B_up,
	B_ge,	B_gs,	B_su,
	B_an,	B_co,	B_ls,	B_or,	B_rs,	B_xo,
};

/* tokens and their corresponding info values */

#define	NTC     "\377"  /* switch to next token class (tc<<1) */
#define	NTCC    '\377'

#define	OC_B	OC_BUILTIN

static const char tokenlist[] ALIGN1 =
	"\1("       NTC
	"\1)"       NTC
	"\1/"       NTC                                 /* REGEXP */
	"\2>>"      "\1>"       "\1|"       NTC         /* OUTRDR */
	"\2++"      "\2--"      NTC                     /* UOPPOST */
	"\2++"      "\2--"      "\1$"       NTC         /* UOPPRE1 */
	"\2=="      "\1="       "\2+="      "\2-="      /* BINOPX */
	"\2*="      "\2/="      "\2%="      "\2^="
	"\1+"       "\1-"       "\3**="     "\2**"
	"\1/"       "\1%"       "\1^"       "\1*"
	"\2!="      "\2>="      "\2<="      "\1>"
	"\1<"       "\2!~"      "\1~"       "\2&&"
	"\2||"      "\1?"       "\1:"       NTC
	"\2in"      NTC
	"\1,"       NTC
	"\1|"       NTC
	"\1+"       "\1-"       "\1!"       NTC         /* UOPPRE2 */
	"\1]"       NTC
	"\1{"       NTC
	"\1}"       NTC
	"\1;"       NTC
	"\1\n"      NTC
	"\2if"      "\2do"      "\3for"     "\5break"   /* STATX */
	"\10continue"           "\6delete"  "\5print"
	"\6printf"  "\4next"    "\10nextfile"
	"\6return"  "\4exit"    NTC
	"\5while"   NTC
	"\4else"    NTC

	"\3and"     "\5compl"   "\6lshift"  "\2or"
	"\6rshift"  "\3xor"
	"\5close"   "\6system"  "\6fflush"  "\5atan2"   /* BUILTIN */
	"\3cos"     "\3exp"     "\3int"     "\3log"
	"\4rand"    "\3sin"     "\4sqrt"    "\5srand"
	"\6gensub"  "\4gsub"    "\5index"   "\6length"
	"\5match"   "\5split"   "\7sprintf" "\3sub"
	"\6substr"  "\7systime" "\10strftime" "\6mktime"
	"\7tolower" "\7toupper" NTC
	"\7getline" NTC
	"\4func"    "\10function"   NTC
	"\5BEGIN"   NTC
	"\3END"     "\0"
	;

static const uint32_t tokeninfo[] = {
	0,
	0,
	OC_REGEXP,
	xS|'a',     xS|'w',     xS|'|',
	OC_UNARY|xV|P(9)|'p',       OC_UNARY|xV|P(9)|'m',
	OC_UNARY|xV|P(9)|'P',       OC_UNARY|xV|P(9)|'M',
	    OC_FIELD|xV|P(5),
	OC_COMPARE|VV|P(39)|5,      OC_MOVE|VV|P(74),
	    OC_REPLACE|NV|P(74)|'+',    OC_REPLACE|NV|P(74)|'-',
	OC_REPLACE|NV|P(74)|'*',    OC_REPLACE|NV|P(74)|'/',
	    OC_REPLACE|NV|P(74)|'%',    OC_REPLACE|NV|P(74)|'&',
	OC_BINARY|NV|P(29)|'+',     OC_BINARY|NV|P(29)|'-',
	    OC_REPLACE|NV|P(74)|'&',    OC_BINARY|NV|P(15)|'&',
	OC_BINARY|NV|P(25)|'/',     OC_BINARY|NV|P(25)|'%',
	    OC_BINARY|NV|P(15)|'&',     OC_BINARY|NV|P(25)|'*',
	OC_COMPARE|VV|P(39)|4,      OC_COMPARE|VV|P(39)|3,
	    OC_COMPARE|VV|P(39)|0,      OC_COMPARE|VV|P(39)|1,
	OC_COMPARE|VV|P(39)|2,      OC_MATCH|Sx|P(45)|'!',
	    OC_MATCH|Sx|P(45)|'~',      OC_LAND|Vx|P(55),
	OC_LOR|Vx|P(59),            OC_TERNARY|Vx|P(64)|'?',
	    OC_COLON|xx|P(67)|':',
	OC_IN|SV|P(49),
	OC_COMMA|SS|P(80),
	OC_PGETLINE|SV|P(37),
	OC_UNARY|xV|P(19)|'+',      OC_UNARY|xV|P(19)|'-',
	    OC_UNARY|xV|P(19)|'!',
	0,
	0,
	0,
	0,
	0,
	ST_IF,          ST_DO,          ST_FOR,         OC_BREAK,
	OC_CONTINUE,                    OC_DELETE|Vx,   OC_PRINT,
	OC_PRINTF,      OC_NEXT,        OC_NEXTFILE,
	OC_RETURN|Vx,   OC_EXIT|Nx,
	ST_WHILE,
	0,

	OC_B|B_an|P(0x83), OC_B|B_co|P(0x41), OC_B|B_ls|P(0x83), OC_B|B_or|P(0x83),
	OC_B|B_rs|P(0x83), OC_B|B_xo|P(0x83),
	OC_FBLTIN|Sx|F_cl, OC_FBLTIN|Sx|F_sy, OC_FBLTIN|Sx|F_ff, OC_B|B_a2|P(0x83),
	OC_FBLTIN|Nx|F_co, OC_FBLTIN|Nx|F_ex, OC_FBLTIN|Nx|F_in, OC_FBLTIN|Nx|F_lg,
	OC_FBLTIN|F_rn,    OC_FBLTIN|Nx|F_si, OC_FBLTIN|Nx|F_sq, OC_FBLTIN|Nx|F_sr,
	OC_B|B_ge|P(0xd6), OC_B|B_gs|P(0xb6), OC_B|B_ix|P(0x9b), OC_FBLTIN|Sx|F_le,
	OC_B|B_ma|P(0x89), OC_B|B_sp|P(0x8b), OC_SPRINTF,        OC_B|B_su|P(0xb6),
	OC_B|B_ss|P(0x8f), OC_FBLTIN|F_ti,    OC_B|B_ti|P(0x0b), OC_B|B_mt|P(0x0b),
	OC_B|B_lo|P(0x49), OC_B|B_up|P(0x49),
	OC_GETLINE|SV|P(0),
	0,	0,
	0,
	0
};

/* internal variable names and their initial values       */
/* asterisk marks SPECIAL vars; $ is just no-named Field0 */
enum {
	CONVFMT,    OFMT,       FS,         OFS,
	ORS,        RS,         RT,         FILENAME,
	SUBSEP,     F0,         ARGIND,     ARGC,
	ARGV,       ERRNO,      FNR,        NR,
	NF,         IGNORECASE,	ENVIRON,    NUM_INTERNAL_VARS
};

static const char vNames[] ALIGN1 =
	"CONVFMT\0" "OFMT\0"    "FS\0*"     "OFS\0"
	"ORS\0"     "RS\0*"     "RT\0"      "FILENAME\0"
	"SUBSEP\0"  "$\0*"      "ARGIND\0"  "ARGC\0"
	"ARGV\0"    "ERRNO\0"   "FNR\0"     "NR\0"
	"NF\0*"     "IGNORECASE\0*" "ENVIRON\0" "\0";

static const char vValues[] ALIGN1 =
	"%.6g\0"    "%.6g\0"    " \0"       " \0"
	"\n\0"      "\n\0"      "\0"        "\0"
	"\034\0"    "\0"        "\377";

/* hash size may grow to these values */
#define FIRST_PRIME 61
static const uint16_t PRIMES[] ALIGN2 = { 251, 1021, 4093, 16381, 65521 };


/* Globals. Split in two parts so that first one is addressed
 * with (mostly short) negative offsets.
 * NB: it's unsafe to put members of type "double"
 * into globals2 (gcc may fail to align them).
 */
struct globals {
	double t_double;
	chain beginseq, mainseq, endseq;
	chain *seq;
	node *break_ptr, *continue_ptr;
	rstream *iF;
	xhash *vhash, *ahash, *fdhash, *fnhash;
	const char *g_progname;
	int g_lineno;
	int nfields;
	int maxfields; /* used in fsrealloc() only */
	var *Fields;
	nvblock *g_cb;
	char *g_pos;
	char *g_buf;
	smallint icase;
	smallint exiting;
	smallint nextrec;
	smallint nextfile;
	smallint is_f0_split;
};
struct globals2 {
	uint32_t t_info; /* often used */
	uint32_t t_tclass;
	char *t_string;
	int t_lineno;
	int t_rollback;

	var *intvar[NUM_INTERNAL_VARS]; /* often used */

	/* former statics from various functions */
	char *split_f0__fstrings;

	uint32_t next_token__save_tclass;
	uint32_t next_token__save_info;
	uint32_t next_token__ltclass;
	smallint next_token__concat_inserted;

	smallint next_input_file__files_happen;
	rstream next_input_file__rsm;

	var *evaluate__fnargs;
	unsigned evaluate__seed;
	regex_t evaluate__sreg;

	var ptest__v;

	tsplitter exec_builtin__tspl;

	/* biggest and least used members go last */
	tsplitter fsplitter, rsplitter;
};
#define G1 (ptr_to_globals[-1])
#define G (*(struct globals2 *)ptr_to_globals)
/* For debug. nm --size-sort awk.o | grep -vi ' [tr] ' */
/*char G1size[sizeof(G1)]; - 0x74 */
/*char Gsize[sizeof(G)]; - 0x1c4 */
/* Trying to keep most of members accessible with short offsets: */
/*char Gofs_seed[offsetof(struct globals2, evaluate__seed)]; - 0x90 */
#define t_double     (G1.t_double    )
#define beginseq     (G1.beginseq    )
#define mainseq      (G1.mainseq     )
#define endseq       (G1.endseq      )
#define seq          (G1.seq         )
#define break_ptr    (G1.break_ptr   )
#define continue_ptr (G1.continue_ptr)
#define iF           (G1.iF          )
#define vhash        (G1.vhash       )
#define ahash        (G1.ahash       )
#define fdhash       (G1.fdhash      )
#define fnhash       (G1.fnhash      )
#define g_progname   (G1.g_progname  )
#define g_lineno     (G1.g_lineno    )
#define nfields      (G1.nfields     )
#define maxfields    (G1.maxfields   )
#define Fields       (G1.Fields      )
#define g_cb         (G1.g_cb        )
#define g_pos        (G1.g_pos       )
#define g_buf        (G1.g_buf       )
#define icase        (G1.icase       )
#define exiting      (G1.exiting     )
#define nextrec      (G1.nextrec     )
#define nextfile     (G1.nextfile    )
#define is_f0_split  (G1.is_f0_split )
#define t_info       (G.t_info      )
#define t_tclass     (G.t_tclass    )
#define t_string     (G.t_string    )
#define t_lineno     (G.t_lineno    )
#define t_rollback   (G.t_rollback  )
#define intvar       (G.intvar      )
#define fsplitter    (G.fsplitter   )
#define rsplitter    (G.rsplitter   )
#define INIT_G() do { \
	SET_PTR_TO_GLOBALS((char*)xzalloc(sizeof(G1)+sizeof(G)) + sizeof(G1)); \
	G.next_token__ltclass = TC_OPTERM; \
	G.evaluate__seed = 1; \
} while (0)


/* function prototypes */
static void handle_special(var *);
static node *parse_expr(uint32_t);
static void chain_group(void);
static var *evaluate(node *, var *);
static rstream *next_input_file(void);
static int fmt_num(char *, int, const char *, double, int);
static int awk_exit(int) NORETURN;

/* ---- error handling ---- */

static const char EMSG_INTERNAL_ERROR[] ALIGN1 = "Internal error";
static const char EMSG_UNEXP_EOS[] ALIGN1 = "Unexpected end of string";
static const char EMSG_UNEXP_TOKEN[] ALIGN1 = "Unexpected token";
static const char EMSG_DIV_BY_ZERO[] ALIGN1 = "Division by zero";
static const char EMSG_INV_FMT[] ALIGN1 = "Invalid format specifier";
static const char EMSG_TOO_FEW_ARGS[] ALIGN1 = "Too few arguments for builtin";
static const char EMSG_NOT_ARRAY[] ALIGN1 = "Not an array";
static const char EMSG_POSSIBLE_ERROR[] ALIGN1 = "Possible syntax error";
static const char EMSG_UNDEF_FUNC[] ALIGN1 = "Call to undefined function";
#if !ENABLE_FEATURE_AWK_LIBM
static const char EMSG_NO_MATH[] ALIGN1 = "Math support is not compiled in";
#endif

static void zero_out_var(var * vp)
{
	memset(vp, 0, sizeof(*vp));
}

static void syntax_error(const char *message) NORETURN;
static void syntax_error(const char *message)
{
	bb_error_msg_and_die("%s:%i: %s", g_progname, g_lineno, message);
}

/* ---- hash stuff ---- */

static unsigned hashidx(const char *name)
{
	unsigned idx = 0;

	while (*name) idx = *name++ + (idx << 6) - idx;
	return idx;
}

/* create new hash */
static xhash *hash_init(void)
{
	xhash *newhash;

	newhash = xzalloc(sizeof(xhash));
	newhash->csize = FIRST_PRIME;
	newhash->items = xzalloc(newhash->csize * sizeof(hash_item *));

	return newhash;
}

/* find item in hash, return ptr to data, NULL if not found */
static void *hash_search(xhash *hash, const char *name)
{
	hash_item *hi;

	hi = hash->items [ hashidx(name) % hash->csize ];
	while (hi) {
		if (strcmp(hi->name, name) == 0)
			return &(hi->data);
		hi = hi->next;
	}
	return NULL;
}

/* grow hash if it becomes too big */
static void hash_rebuild(xhash *hash)
{
	unsigned newsize, i, idx;
	hash_item **newitems, *hi, *thi;

	if (hash->nprime == ARRAY_SIZE(PRIMES))
		return;

	newsize = PRIMES[hash->nprime++];
	newitems = xzalloc(newsize * sizeof(hash_item *));

	for (i = 0; i < hash->csize; i++) {
		hi = hash->items[i];
		while (hi) {
			thi = hi;
			hi = thi->next;
			idx = hashidx(thi->name) % newsize;
			thi->next = newitems[idx];
			newitems[idx] = thi;
		}
	}

	free(hash->items);
	hash->csize = newsize;
	hash->items = newitems;
}

/* find item in hash, add it if necessary. Return ptr to data */
static void *hash_find(xhash *hash, const char *name)
{
	hash_item *hi;
	unsigned idx;
	int l;

	hi = hash_search(hash, name);
	if (!hi) {
		if (++hash->nel / hash->csize > 10)
			hash_rebuild(hash);

		l = strlen(name) + 1;
		hi = xzalloc(sizeof(*hi) + l);
		strcpy(hi->name, name);

		idx = hashidx(name) % hash->csize;
		hi->next = hash->items[idx];
		hash->items[idx] = hi;
		hash->glen += l;
	}
	return &(hi->data);
}

#define findvar(hash, name) ((var*)    hash_find((hash), (name)))
#define newvar(name)        ((var*)    hash_find(vhash, (name)))
#define newfile(name)       ((rstream*)hash_find(fdhash, (name)))
#define newfunc(name)       ((func*)   hash_find(fnhash, (name)))

static void hash_remove(xhash *hash, const char *name)
{
	hash_item *hi, **phi;

	phi = &(hash->items[hashidx(name) % hash->csize]);
	while (*phi) {
		hi = *phi;
		if (strcmp(hi->name, name) == 0) {
			hash->glen -= (strlen(name) + 1);
			hash->nel--;
			*phi = hi->next;
			free(hi);
			break;
		}
		phi = &(hi->next);
	}
}

/* ------ some useful functions ------ */

static void skip_spaces(char **s)
{
	char *p = *s;

	while (1) {
		if (*p == '\\' && p[1] == '\n') {
			p++;
			t_lineno++;
		} else if (*p != ' ' && *p != '\t') {
			break;
		}
		p++;
	}
	*s = p;
}

static char *nextword(char **s)
{
	char *p = *s;

	while (*(*s)++) /* */;

	return p;
}

static char nextchar(char **s)
{
	char c, *pps;

	c = *((*s)++);
	pps = *s;
	if (c == '\\') c = bb_process_escape_sequence((const char**)s);
	if (c == '\\' && *s == pps) c = *((*s)++);
	return c;
}

static ALWAYS_INLINE int isalnum_(int c)
{
	return (isalnum(c) || c == '_');
}

static double my_strtod(char **pp)
{
#if ENABLE_DESKTOP
	if ((*pp)[0] == '0'
	 && ((((*pp)[1] | 0x20) == 'x') || isdigit((*pp)[1]))
	) {
		return strtoull(*pp, pp, 0);
	}
#endif
	return strtod(*pp, pp);
}

/* -------- working with variables (set/get/copy/etc) -------- */

static xhash *iamarray(var *v)
{
	var *a = v;

	while (a->type & VF_CHILD)
		a = a->x.parent;

	if (!(a->type & VF_ARRAY)) {
		a->type |= VF_ARRAY;
		a->x.array = hash_init();
	}
	return a->x.array;
}

static void clear_array(xhash *array)
{
	unsigned i;
	hash_item *hi, *thi;

	for (i = 0; i < array->csize; i++) {
		hi = array->items[i];
		while (hi) {
			thi = hi;
			hi = hi->next;
			free(thi->data.v.string);
			free(thi);
		}
		array->items[i] = NULL;
	}
	array->glen = array->nel = 0;
}

/* clear a variable */
static var *clrvar(var *v)
{
	if (!(v->type & VF_FSTR))
		free(v->string);

	v->type &= VF_DONTTOUCH;
	v->type |= VF_DIRTY;
	v->string = NULL;
	return v;
}

/* assign string value to variable */
static var *setvar_p(var *v, char *value)
{
	clrvar(v);
	v->string = value;
	handle_special(v);
	return v;
}

/* same as setvar_p but make a copy of string */
static var *setvar_s(var *v, const char *value)
{
	return setvar_p(v, (value && *value) ? xstrdup(value) : NULL);
}

/* same as setvar_s but set USER flag */
static var *setvar_u(var *v, const char *value)
{
	setvar_s(v, value);
	v->type |= VF_USER;
	return v;
}

/* set array element to user string */
static void setari_u(var *a, int idx, const char *s)
{
	var *v;

	v = findvar(iamarray(a), itoa(idx));
	setvar_u(v, s);
}

/* assign numeric value to variable */
static var *setvar_i(var *v, double value)
{
	clrvar(v);
	v->type |= VF_NUMBER;
	v->number = value;
	handle_special(v);
	return v;
}

static const char *getvar_s(var *v)
{
	/* if v is numeric and has no cached string, convert it to string */
	if ((v->type & (VF_NUMBER | VF_CACHED)) == VF_NUMBER) {
		fmt_num(g_buf, MAXVARFMT, getvar_s(intvar[CONVFMT]), v->number, TRUE);
		v->string = xstrdup(g_buf);
		v->type |= VF_CACHED;
	}
	return (v->string == NULL) ? "" : v->string;
}

static double getvar_i(var *v)
{
	char *s;

	if ((v->type & (VF_NUMBER | VF_CACHED)) == 0) {
		v->number = 0;
		s = v->string;
		if (s && *s) {
			v->number = my_strtod(&s);
			if (v->type & VF_USER) {
				skip_spaces(&s);
				if (*s != '\0')
					v->type &= ~VF_USER;
			}
		} else {
			v->type &= ~VF_USER;
		}
		v->type |= VF_CACHED;
	}
	return v->number;
}

/* Used for operands of bitwise ops */
static unsigned long getvar_i_int(var *v)
{
	double d = getvar_i(v);

	/* Casting doubles to longs is undefined for values outside
	 * of target type range. Try to widen it as much as possible */
	if (d >= 0)
		return (unsigned long)d;
	/* Why? Think about d == -4294967295.0 (assuming 32bit longs) */
	return - (long) (unsigned long) (-d);
}

static var *copyvar(var *dest, const var *src)
{
	if (dest != src) {
		clrvar(dest);
		dest->type |= (src->type & ~(VF_DONTTOUCH | VF_FSTR));
		dest->number = src->number;
		if (src->string)
			dest->string = xstrdup(src->string);
	}
	handle_special(dest);
	return dest;
}

static var *incvar(var *v)
{
	return setvar_i(v, getvar_i(v) + 1.);
}

/* return true if v is number or numeric string */
static int is_numeric(var *v)
{
	getvar_i(v);
	return ((v->type ^ VF_DIRTY) & (VF_NUMBER | VF_USER | VF_DIRTY));
}

/* return 1 when value of v corresponds to true, 0 otherwise */
static int istrue(var *v)
{
	if (is_numeric(v))
		return (v->number == 0) ? 0 : 1;
	return (v->string && *(v->string)) ? 1 : 0;
}

/* temporary variables allocator. Last allocated should be first freed */
static var *nvalloc(int n)
{
	nvblock *pb = NULL;
	var *v, *r;
	int size;

	while (g_cb) {
		pb = g_cb;
		if ((g_cb->pos - g_cb->nv) + n <= g_cb->size) break;
		g_cb = g_cb->next;
	}

	if (!g_cb) {
		size = (n <= MINNVBLOCK) ? MINNVBLOCK : n;
		g_cb = xzalloc(sizeof(nvblock) + size * sizeof(var));
		g_cb->size = size;
		g_cb->pos = g_cb->nv;
		g_cb->prev = pb;
		/*g_cb->next = NULL; - xzalloc did it */
		if (pb) pb->next = g_cb;
	}

	v = r = g_cb->pos;
	g_cb->pos += n;

	while (v < g_cb->pos) {
		v->type = 0;
		v->string = NULL;
		v++;
	}

	return r;
}

static void nvfree(var *v)
{
	var *p;

	if (v < g_cb->nv || v >= g_cb->pos)
		syntax_error(EMSG_INTERNAL_ERROR);

	for (p = v; p < g_cb->pos; p++) {
		if ((p->type & (VF_ARRAY | VF_CHILD)) == VF_ARRAY) {
			clear_array(iamarray(p));
			free(p->x.array->items);
			free(p->x.array);
		}
		if (p->type & VF_WALK)
			free(p->x.walker);

		clrvar(p);
	}

	g_cb->pos = v;
	while (g_cb->prev && g_cb->pos == g_cb->nv) {
		g_cb = g_cb->prev;
	}
}

/* ------- awk program text parsing ------- */

/* Parse next token pointed by global pos, place results into global ttt.
 * If token isn't expected, give away. Return token class
 */
static uint32_t next_token(uint32_t expected)
{
#define concat_inserted (G.next_token__concat_inserted)
#define save_tclass     (G.next_token__save_tclass)
#define save_info       (G.next_token__save_info)
/* Initialized to TC_OPTERM: */
#define ltclass         (G.next_token__ltclass)

	char *p, *pp, *s;
	const char *tl;
	uint32_t tc;
	const uint32_t *ti;
	int l;

	if (t_rollback) {
		t_rollback = FALSE;

	} else if (concat_inserted) {
		concat_inserted = FALSE;
		t_tclass = save_tclass;
		t_info = save_info;

	} else {
		p = g_pos;
 readnext:
		skip_spaces(&p);
		g_lineno = t_lineno;
		if (*p == '#')
			while (*p != '\n' && *p != '\0')
				p++;

		if (*p == '\n')
			t_lineno++;

		if (*p == '\0') {
			tc = TC_EOF;

		} else if (*p == '\"') {
			/* it's a string */
			t_string = s = ++p;
			while (*p != '\"') {
				if (*p == '\0' || *p == '\n')
					syntax_error(EMSG_UNEXP_EOS);
				*(s++) = nextchar(&p);
			}
			p++;
			*s = '\0';
			tc = TC_STRING;

		} else if ((expected & TC_REGEXP) && *p == '/') {
			/* it's regexp */
			t_string = s = ++p;
			while (*p != '/') {
				if (*p == '\0' || *p == '\n')
					syntax_error(EMSG_UNEXP_EOS);
				*s = *p++;
				if (*s++ == '\\') {
					pp = p;
					*(s-1) = bb_process_escape_sequence((const char **)&p);
					if (*pp == '\\')
						*s++ = '\\';
					if (p == pp)
						*s++ = *p++;
				}
			}
			p++;
			*s = '\0';
			tc = TC_REGEXP;

		} else if (*p == '.' || isdigit(*p)) {
			/* it's a number */
			t_double = my_strtod(&p);
			if (*p == '.')
				syntax_error(EMSG_UNEXP_TOKEN);
			tc = TC_NUMBER;

		} else {
			/* search for something known */
			tl = tokenlist;
			tc = 0x00000001;
			ti = tokeninfo;
			while (*tl) {
				l = *(tl++);
				if (l == NTCC) {
					tc <<= 1;
					continue;
				}
				/* if token class is expected, token
				 * matches and it's not a longer word,
				 * then this is what we are looking for
				 */
				if ((tc & (expected | TC_WORD | TC_NEWLINE))
				 && *tl == *p && strncmp(p, tl, l) == 0
				 && !((tc & TC_WORD) && isalnum_(p[l]))
				) {
					t_info = *ti;
					p += l;
					break;
				}
				ti++;
				tl += l;
			}

			if (!*tl) {
				/* it's a name (var/array/function),
				 * otherwise it's something wrong
				 */
				if (!isalnum_(*p))
					syntax_error(EMSG_UNEXP_TOKEN);

				t_string = --p;
				while (isalnum_(*(++p))) {
					*(p-1) = *p;
				}
				*(p-1) = '\0';
				tc = TC_VARIABLE;
				/* also consume whitespace between functionname and bracket */
				if (!(expected & TC_VARIABLE))
					skip_spaces(&p);
				if (*p == '(') {
					tc = TC_FUNCTION;
				} else {
					if (*p == '[') {
						p++;
						tc = TC_ARRAY;
					}
				}
			}
		}
		g_pos = p;

		/* skipping newlines in some cases */
		if ((ltclass & TC_NOTERM) && (tc & TC_NEWLINE))
			goto readnext;

		/* insert concatenation operator when needed */
		if ((ltclass & TC_CONCAT1) && (tc & TC_CONCAT2) && (expected & TC_BINOP)) {
			concat_inserted = TRUE;
			save_tclass = tc;
			save_info = t_info;
			tc = TC_BINOP;
			t_info = OC_CONCAT | SS | P(35);
		}

		t_tclass = tc;
	}
	ltclass = t_tclass;

	/* Are we ready for this? */
	if (!(ltclass & expected))
		syntax_error((ltclass & (TC_NEWLINE | TC_EOF)) ?
				EMSG_UNEXP_EOS : EMSG_UNEXP_TOKEN);

	return ltclass;
#undef concat_inserted
#undef save_tclass
#undef save_info
#undef ltclass
}

static void rollback_token(void)
{
	t_rollback = TRUE;
}

static node *new_node(uint32_t info)
{
	node *n;

	n = xzalloc(sizeof(node));
	n->info = info;
	n->lineno = g_lineno;
	return n;
}

static node *mk_re_node(const char *s, node *n, regex_t *re)
{
	n->info = OC_REGEXP;
	n->l.re = re;
	n->r.ire = re + 1;
	xregcomp(re, s, REG_EXTENDED);
	xregcomp(re + 1, s, REG_EXTENDED | REG_ICASE);

	return n;
}

static node *condition(void)
{
	next_token(TC_SEQSTART);
	return parse_expr(TC_SEQTERM);
}

/* parse expression terminated by given argument, return ptr
 * to built subtree. Terminator is eaten by parse_expr */
static node *parse_expr(uint32_t iexp)
{
	node sn;
	node *cn = &sn;
	node *vn, *glptr;
	uint32_t tc, xtc;
	var *v;

	sn.info = PRIMASK;
	sn.r.n = glptr = NULL;
	xtc = TC_OPERAND | TC_UOPPRE | TC_REGEXP | iexp;

	while (!((tc = next_token(xtc)) & iexp)) {
		if (glptr && (t_info == (OC_COMPARE | VV | P(39) | 2))) {
			/* input redirection (<) attached to glptr node */
			cn = glptr->l.n = new_node(OC_CONCAT | SS | P(37));
			cn->a.n = glptr;
			xtc = TC_OPERAND | TC_UOPPRE;
			glptr = NULL;

		} else if (tc & (TC_BINOP | TC_UOPPOST)) {
			/* for binary and postfix-unary operators, jump back over
			 * previous operators with higher priority */
			vn = cn;
			while ( ((t_info & PRIMASK) > (vn->a.n->info & PRIMASK2))
			 || ((t_info == vn->info) && ((t_info & OPCLSMASK) == OC_COLON)) )
				vn = vn->a.n;
			if ((t_info & OPCLSMASK) == OC_TERNARY)
				t_info += P(6);
			cn = vn->a.n->r.n = new_node(t_info);
			cn->a.n = vn->a.n;
			if (tc & TC_BINOP) {
				cn->l.n = vn;
				xtc = TC_OPERAND | TC_UOPPRE | TC_REGEXP;
				if ((t_info & OPCLSMASK) == OC_PGETLINE) {
					/* it's a pipe */
					next_token(TC_GETLINE);
					/* give maximum priority to this pipe */
					cn->info &= ~PRIMASK;
					xtc = TC_OPERAND | TC_UOPPRE | TC_BINOP | iexp;
				}
			} else {
				cn->r.n = vn;
				xtc = TC_OPERAND | TC_UOPPRE | TC_BINOP | iexp;
			}
			vn->a.n = cn;

		} else {
			/* for operands and prefix-unary operators, attach them
			 * to last node */
			vn = cn;
			cn = vn->r.n = new_node(t_info);
			cn->a.n = vn;
			xtc = TC_OPERAND | TC_UOPPRE | TC_REGEXP;
			if (tc & (TC_OPERAND | TC_REGEXP)) {
				xtc = TC_UOPPRE | TC_UOPPOST | TC_BINOP | TC_OPERAND | iexp;
				/* one should be very careful with switch on tclass -
				 * only simple tclasses should be used! */
				switch (tc) {
				case TC_VARIABLE:
				case TC_ARRAY:
					cn->info = OC_VAR;
					v = hash_search(ahash, t_string);
					if (v != NULL) {
						cn->info = OC_FNARG;
						cn->l.i = v->x.aidx;
					} else {
						cn->l.v = newvar(t_string);
					}
					if (tc & TC_ARRAY) {
						cn->info |= xS;
						cn->r.n = parse_expr(TC_ARRTERM);
					}
					break;

				case TC_NUMBER:
				case TC_STRING:
					cn->info = OC_VAR;
					v = cn->l.v = xzalloc(sizeof(var));
					if (tc & TC_NUMBER)
						setvar_i(v, t_double);
					else
						setvar_s(v, t_string);
					break;

				case TC_REGEXP:
					mk_re_node(t_string, cn, xzalloc(sizeof(regex_t)*2));
					break;

				case TC_FUNCTION:
					cn->info = OC_FUNC;
					cn->r.f = newfunc(t_string);
					cn->l.n = condition();
					break;

				case TC_SEQSTART:
					cn = vn->r.n = parse_expr(TC_SEQTERM);
					cn->a.n = vn;
					break;

				case TC_GETLINE:
					glptr = cn;
					xtc = TC_OPERAND | TC_UOPPRE | TC_BINOP | iexp;
					break;

				case TC_BUILTIN:
					cn->l.n = condition();
					break;
				}
			}
		}
	}
	return sn.r.n;
}

/* add node to chain. Return ptr to alloc'd node */
static node *chain_node(uint32_t info)
{
	node *n;

	if (!seq->first)
		seq->first = seq->last = new_node(0);

	if (seq->programname != g_progname) {
		seq->programname = g_progname;
		n = chain_node(OC_NEWSOURCE);
		n->l.s = xstrdup(g_progname);
	}

	n = seq->last;
	n->info = info;
	seq->last = n->a.n = new_node(OC_DONE);

	return n;
}

static void chain_expr(uint32_t info)
{
	node *n;

	n = chain_node(info);
	n->l.n = parse_expr(TC_OPTERM | TC_GRPTERM);
	if (t_tclass & TC_GRPTERM)
		rollback_token();
}

static node *chain_loop(node *nn)
{
	node *n, *n2, *save_brk, *save_cont;

	save_brk = break_ptr;
	save_cont = continue_ptr;

	n = chain_node(OC_BR | Vx);
	continue_ptr = new_node(OC_EXEC);
	break_ptr = new_node(OC_EXEC);
	chain_group();
	n2 = chain_node(OC_EXEC | Vx);
	n2->l.n = nn;
	n2->a.n = n;
	continue_ptr->a.n = n2;
	break_ptr->a.n = n->r.n = seq->last;

	continue_ptr = save_cont;
	break_ptr = save_brk;

	return n;
}

/* parse group and attach it to chain */
static void chain_group(void)
{
	uint32_t c;
	node *n, *n2, *n3;

	do {
		c = next_token(TC_GRPSEQ);
	} while (c & TC_NEWLINE);

	if (c & TC_GRPSTART) {
		while (next_token(TC_GRPSEQ | TC_GRPTERM) != TC_GRPTERM) {
			if (t_tclass & TC_NEWLINE) continue;
			rollback_token();
			chain_group();
		}
	} else if (c & (TC_OPSEQ | TC_OPTERM)) {
		rollback_token();
		chain_expr(OC_EXEC | Vx);
	} else {						/* TC_STATEMNT */
		switch (t_info & OPCLSMASK) {
		case ST_IF:
			n = chain_node(OC_BR | Vx);
			n->l.n = condition();
			chain_group();
			n2 = chain_node(OC_EXEC);
			n->r.n = seq->last;
			if (next_token(TC_GRPSEQ | TC_GRPTERM | TC_ELSE) == TC_ELSE) {
				chain_group();
				n2->a.n = seq->last;
			} else {
				rollback_token();
			}
			break;

		case ST_WHILE:
			n2 = condition();
			n = chain_loop(NULL);
			n->l.n = n2;
			break;

		case ST_DO:
			n2 = chain_node(OC_EXEC);
			n = chain_loop(NULL);
			n2->a.n = n->a.n;
			next_token(TC_WHILE);
			n->l.n = condition();
			break;

		case ST_FOR:
			next_token(TC_SEQSTART);
			n2 = parse_expr(TC_SEMICOL | TC_SEQTERM);
			if (t_tclass & TC_SEQTERM) {	/* for-in */
				if ((n2->info & OPCLSMASK) != OC_IN)
					syntax_error(EMSG_UNEXP_TOKEN);
				n = chain_node(OC_WALKINIT | VV);
				n->l.n = n2->l.n;
				n->r.n = n2->r.n;
				n = chain_loop(NULL);
				n->info = OC_WALKNEXT | Vx;
				n->l.n = n2->l.n;
			} else {			/* for (;;) */
				n = chain_node(OC_EXEC | Vx);
				n->l.n = n2;
				n2 = parse_expr(TC_SEMICOL);
				n3 = parse_expr(TC_SEQTERM);
				n = chain_loop(n3);
				n->l.n = n2;
				if (!n2)
					n->info = OC_EXEC;
			}
			break;

		case OC_PRINT:
		case OC_PRINTF:
			n = chain_node(t_info);
			n->l.n = parse_expr(TC_OPTERM | TC_OUTRDR | TC_GRPTERM);
			if (t_tclass & TC_OUTRDR) {
				n->info |= t_info;
				n->r.n = parse_expr(TC_OPTERM | TC_GRPTERM);
			}
			if (t_tclass & TC_GRPTERM)
				rollback_token();
			break;

		case OC_BREAK:
			n = chain_node(OC_EXEC);
			n->a.n = break_ptr;
			break;

		case OC_CONTINUE:
			n = chain_node(OC_EXEC);
			n->a.n = continue_ptr;
			break;

		/* delete, next, nextfile, return, exit */
		default:
			chain_expr(t_info);
		}
	}
}

static void parse_program(char *p)
{
	uint32_t tclass;
	node *cn;
	func *f;
	var *v;

	g_pos = p;
	t_lineno = 1;
	while ((tclass = next_token(TC_EOF | TC_OPSEQ | TC_GRPSTART |
			TC_OPTERM | TC_BEGIN | TC_END | TC_FUNCDECL)) != TC_EOF) {

		if (tclass & TC_OPTERM)
			continue;

		seq = &mainseq;
		if (tclass & TC_BEGIN) {
			seq = &beginseq;
			chain_group();

		} else if (tclass & TC_END) {
			seq = &endseq;
			chain_group();

		} else if (tclass & TC_FUNCDECL) {
			next_token(TC_FUNCTION);
			g_pos++;
			f = newfunc(t_string);
			f->body.first = NULL;
			f->nargs = 0;
			while (next_token(TC_VARIABLE | TC_SEQTERM) & TC_VARIABLE) {
				v = findvar(ahash, t_string);
				v->x.aidx = (f->nargs)++;

				if (next_token(TC_COMMA | TC_SEQTERM) & TC_SEQTERM)
					break;
			}
			seq = &(f->body);
			chain_group();
			clear_array(ahash);

		} else if (tclass & TC_OPSEQ) {
			rollback_token();
			cn = chain_node(OC_TEST);
			cn->l.n = parse_expr(TC_OPTERM | TC_EOF | TC_GRPSTART);
			if (t_tclass & TC_GRPSTART) {
				rollback_token();
				chain_group();
			} else {
				chain_node(OC_PRINT);
			}
			cn->r.n = mainseq.last;

		} else /* if (tclass & TC_GRPSTART) */ {
			rollback_token();
			chain_group();
		}
	}
}


/* -------- program execution part -------- */

static node *mk_splitter(const char *s, tsplitter *spl)
{
	regex_t *re, *ire;
	node *n;

	re = &spl->re[0];
	ire = &spl->re[1];
	n = &spl->n;
	if ((n->info & OPCLSMASK) == OC_REGEXP) {
		regfree(re);
		regfree(ire); // TODO: nuke ire, use re+1?
	}
	if (strlen(s) > 1) {
		mk_re_node(s, n, re);
	} else {
		n->info = (uint32_t) *s;
	}

	return n;
}

/* use node as a regular expression. Supplied with node ptr and regex_t
 * storage space. Return ptr to regex (if result points to preg, it should
 * be later regfree'd manually
 */
static regex_t *as_regex(node *op, regex_t *preg)
{
	int cflags;
	var *v;
	const char *s;

	if ((op->info & OPCLSMASK) == OC_REGEXP) {
		return icase ? op->r.ire : op->l.re;
	}
	v = nvalloc(1);
	s = getvar_s(evaluate(op, v));

	cflags = icase ? REG_EXTENDED | REG_ICASE : REG_EXTENDED;
	/* Testcase where REG_EXTENDED fails (unpaired '{'):
	 * echo Hi | awk 'gsub("@(samp|code|file)\{","");'
	 * gawk 3.1.5 eats this. We revert to ~REG_EXTENDED
	 * (maybe gsub is not supposed to use REG_EXTENDED?).
	 */
	if (regcomp(preg, s, cflags)) {
		cflags &= ~REG_EXTENDED;
		xregcomp(preg, s, cflags);
	}
	nvfree(v);
	return preg;
}

/* gradually increasing buffer */
static void qrealloc(char **b, int n, int *size)
{
	if (!*b || n >= *size) {
		*size = n + (n>>1) + 80;
		*b = xrealloc(*b, *size);
	}
}

/* resize field storage space */
static void fsrealloc(int size)
{
	int i;

	if (size >= maxfields) {
		i = maxfields;
		maxfields = size + 16;
		Fields = xrealloc(Fields, maxfields * sizeof(var));
		for (; i < maxfields; i++) {
			Fields[i].type = VF_SPECIAL;
			Fields[i].string = NULL;
		}
	}

	if (size < nfields) {
		for (i = size; i < nfields; i++) {
			clrvar(Fields + i);
		}
	}
	nfields = size;
}

static int awk_split(const char *s, node *spl, char **slist)
{
	int l, n = 0;
	char c[4];
	char *s1;
	regmatch_t pmatch[2]; // TODO: why [2]? [1] is enough...

	/* in worst case, each char would be a separate field */
	*slist = s1 = xzalloc(strlen(s) * 2 + 3);
	strcpy(s1, s);

	c[0] = c[1] = (char)spl->info;
	c[2] = c[3] = '\0';
	if (*getvar_s(intvar[RS]) == '\0')
		c[2] = '\n';

	if ((spl->info & OPCLSMASK) == OC_REGEXP) {  /* regex split */
		if (!*s)
			return n; /* "": zero fields */
		n++; /* at least one field will be there */
		do {
			l = strcspn(s, c+2); /* len till next NUL or \n */
			if (regexec(icase ? spl->r.ire : spl->l.re, s, 1, pmatch, 0) == 0
			 && pmatch[0].rm_so <= l
			) {
				l = pmatch[0].rm_so;
				if (pmatch[0].rm_eo == 0) {
					l++;
					pmatch[0].rm_eo++;
				}
				n++; /* we saw yet another delimiter */
			} else {
				pmatch[0].rm_eo = l;
				if (s[l])
					pmatch[0].rm_eo++;
			}
			memcpy(s1, s, l);
			/* make sure we remove *all* of the separator chars */
			do {
				s1[l] = '\0';
			} while (++l < pmatch[0].rm_eo);
			nextword(&s1);
			s += pmatch[0].rm_eo;
		} while (*s);
		return n;
	}
	if (c[0] == '\0') {  /* null split */
		while (*s) {
			*s1++ = *s++;
			*s1++ = '\0';
			n++;
		}
		return n;
	}
	if (c[0] != ' ') {  /* single-character split */
		if (icase) {
			c[0] = toupper(c[0]);
			c[1] = tolower(c[1]);
		}
		if (*s1) n++;
		while ((s1 = strpbrk(s1, c))) {
			*s1++ = '\0';
			n++;
		}
		return n;
	}
	/* space split */
	while (*s) {
		s = skip_whitespace(s);
		if (!*s) break;
		n++;
		while (*s && !isspace(*s))
			*s1++ = *s++;
		*s1++ = '\0';
	}
	return n;
}

static void split_f0(void)
{
/* static char *fstrings; */
#define fstrings (G.split_f0__fstrings)

	int i, n;
	char *s;

	if (is_f0_split)
		return;

	is_f0_split = TRUE;
	free(fstrings);
	fsrealloc(0);
	n = awk_split(getvar_s(intvar[F0]), &fsplitter.n, &fstrings);
	fsrealloc(n);
	s = fstrings;
	for (i = 0; i < n; i++) {
		Fields[i].string = nextword(&s);
		Fields[i].type |= (VF_FSTR | VF_USER | VF_DIRTY);
	}

	/* set NF manually to avoid side effects */
	clrvar(intvar[NF]);
	intvar[NF]->type = VF_NUMBER | VF_SPECIAL;
	intvar[NF]->number = nfields;
#undef fstrings
}

/* perform additional actions when some internal variables changed */
static void handle_special(var *v)
{
	int n;
	char *b;
	const char *sep, *s;
	int sl, l, len, i, bsize;

	if (!(v->type & VF_SPECIAL))
		return;

	if (v == intvar[NF]) {
		n = (int)getvar_i(v);
		fsrealloc(n);

		/* recalculate $0 */
		sep = getvar_s(intvar[OFS]);
		sl = strlen(sep);
		b = NULL;
		len = 0;
		for (i = 0; i < n; i++) {
			s = getvar_s(&Fields[i]);
			l = strlen(s);
			if (b) {
				memcpy(b+len, sep, sl);
				len += sl;
			}
			qrealloc(&b, len+l+sl, &bsize);
			memcpy(b+len, s, l);
			len += l;
		}
		if (b)
			b[len] = '\0';
		setvar_p(intvar[F0], b);
		is_f0_split = TRUE;

	} else if (v == intvar[F0]) {
		is_f0_split = FALSE;

	} else if (v == intvar[FS]) {
		mk_splitter(getvar_s(v), &fsplitter);

	} else if (v == intvar[RS]) {
		mk_splitter(getvar_s(v), &rsplitter);

	} else if (v == intvar[IGNORECASE]) {
		icase = istrue(v);

	} else {				/* $n */
		n = getvar_i(intvar[NF]);
		setvar_i(intvar[NF], n > v-Fields ? n : v-Fields+1);
		/* right here v is invalid. Just to note... */
	}
}

/* step through func/builtin/etc arguments */
static node *nextarg(node **pn)
{
	node *n;

	n = *pn;
	if (n && (n->info & OPCLSMASK) == OC_COMMA) {
		*pn = n->r.n;
		n = n->l.n;
	} else {
		*pn = NULL;
	}
	return n;
}

static void hashwalk_init(var *v, xhash *array)
{
	char **w;
	hash_item *hi;
	unsigned i;

	if (v->type & VF_WALK)
		free(v->x.walker);

	v->type |= VF_WALK;
	w = v->x.walker = xzalloc(2 + 2*sizeof(char *) + array->glen);
	w[0] = w[1] = (char *)(w + 2);
	for (i = 0; i < array->csize; i++) {
		hi = array->items[i];
		while (hi) {
			strcpy(*w, hi->name);
			nextword(w);
			hi = hi->next;
		}
	}
}

static int hashwalk_next(var *v)
{
	char **w;

	w = v->x.walker;
	if (w[1] == w[0])
		return FALSE;

	setvar_s(v, nextword(w+1));
	return TRUE;
}

/* evaluate node, return 1 when result is true, 0 otherwise */
static int ptest(node *pattern)
{
	/* ptest__v is "static": to save stack space? */
	return istrue(evaluate(pattern, &G.ptest__v));
}

/* read next record from stream rsm into a variable v */
static int awk_getline(rstream *rsm, var *v)
{
	char *b;
	regmatch_t pmatch[2];
	int a, p, pp=0, size;
	int fd, so, eo, r, rp;
	char c, *m, *s;

	/* we're using our own buffer since we need access to accumulating
	 * characters
	 */
	fd = fileno(rsm->F);
	m = rsm->buffer;
	a = rsm->adv;
	p = rsm->pos;
	size = rsm->size;
	c = (char) rsplitter.n.info;
	rp = 0;

	if (!m) qrealloc(&m, 256, &size);
	do {
		b = m + a;
		so = eo = p;
		r = 1;
		if (p > 0) {
			if ((rsplitter.n.info & OPCLSMASK) == OC_REGEXP) {
				if (regexec(icase ? rsplitter.n.r.ire : rsplitter.n.l.re,
							b, 1, pmatch, 0) == 0) {
					so = pmatch[0].rm_so;
					eo = pmatch[0].rm_eo;
					if (b[eo] != '\0')
						break;
				}
			} else if (c != '\0') {
				s = strchr(b+pp, c);
				if (!s) s = memchr(b+pp, '\0', p - pp);
				if (s) {
					so = eo = s-b;
					eo++;
					break;
				}
			} else {
				while (b[rp] == '\n')
					rp++;
				s = strstr(b+rp, "\n\n");
				if (s) {
					so = eo = s-b;
					while (b[eo] == '\n') eo++;
					if (b[eo] != '\0')
						break;
				}
			}
		}

		if (a > 0) {
			memmove(m, (const void *)(m+a), p+1);
			b = m;
			a = 0;
		}

		qrealloc(&m, a+p+128, &size);
		b = m + a;
		pp = p;
		p += safe_read(fd, b+p, size-p-1);
		if (p < pp) {
			p = 0;
			r = 0;
			setvar_i(intvar[ERRNO], errno);
		}
		b[p] = '\0';

	} while (p > pp);

	if (p == 0) {
		r--;
	} else {
		c = b[so]; b[so] = '\0';
		setvar_s(v, b+rp);
		v->type |= VF_USER;
		b[so] = c;
		c = b[eo]; b[eo] = '\0';
		setvar_s(intvar[RT], b+so);
		b[eo] = c;
	}

	rsm->buffer = m;
	rsm->adv = a + eo;
	rsm->pos = p - eo;
	rsm->size = size;

	return r;
}

static int fmt_num(char *b, int size, const char *format, double n, int int_as_int)
{
	int r = 0;
	char c;
	const char *s = format;

	if (int_as_int && n == (int)n) {
		r = snprintf(b, size, "%d", (int)n);
	} else {
		do { c = *s; } while (c && *++s);
		if (strchr("diouxX", c)) {
			r = snprintf(b, size, format, (int)n);
		} else if (strchr("eEfgG", c)) {
			r = snprintf(b, size, format, n);
		} else {
			syntax_error(EMSG_INV_FMT);
		}
	}
	return r;
}

/* formatted output into an allocated buffer, return ptr to buffer */
static char *awk_printf(node *n)
{
	char *b = NULL;
	char *fmt, *s, *f;
	const char *s1;
	int i, j, incr, bsize;
	char c, c1;
	var *v, *arg;

	v = nvalloc(1);
	fmt = f = xstrdup(getvar_s(evaluate(nextarg(&n), v)));

	i = 0;
	while (*f) {
		s = f;
		while (*f && (*f != '%' || *(++f) == '%'))
			f++;
		while (*f && !isalpha(*f)) {
			if (*f == '*')
				syntax_error("%*x formats are not supported");
			f++;
		}

		incr = (f - s) + MAXVARFMT;
		qrealloc(&b, incr + i, &bsize);
		c = *f;
		if (c != '\0') f++;
		c1 = *f;
		*f = '\0';
		arg = evaluate(nextarg(&n), v);

		j = i;
		if (c == 'c' || !c) {
			i += sprintf(b+i, s, is_numeric(arg) ?
					(char)getvar_i(arg) : *getvar_s(arg));
		} else if (c == 's') {
			s1 = getvar_s(arg);
			qrealloc(&b, incr+i+strlen(s1), &bsize);
			i += sprintf(b+i, s, s1);
		} else {
			i += fmt_num(b+i, incr, s, getvar_i(arg), FALSE);
		}
		*f = c1;

		/* if there was an error while sprintf, return value is negative */
		if (i < j) i = j;
	}

	b = xrealloc(b, i + 1);
	free(fmt);
	nvfree(v);
	b[i] = '\0';
	return b;
}

/* common substitution routine
 * replace (nm) substring of (src) that match (n) with (repl), store
 * result into (dest), return number of substitutions. If nm=0, replace
 * all matches. If src or dst is NULL, use $0. If ex=TRUE, enable
 * subexpression matching (\1-\9)
 */
static int awk_sub(node *rn, const char *repl, int nm, var *src, var *dest, int ex)
{
	char *ds = NULL;
	const char *s;
	const char *sp;
	int c, i, j, di, rl, so, eo, nbs, n, dssize;
	regmatch_t pmatch[10];
	regex_t sreg, *re;

	re = as_regex(rn, &sreg);
	if (!src) src = intvar[F0];
	if (!dest) dest = intvar[F0];

	i = di = 0;
	sp = getvar_s(src);
	rl = strlen(repl);
	while (regexec(re, sp, 10, pmatch, sp==getvar_s(src) ? 0 : REG_NOTBOL) == 0) {
		so = pmatch[0].rm_so;
		eo = pmatch[0].rm_eo;

		qrealloc(&ds, di + eo + rl, &dssize);
		memcpy(ds + di, sp, eo);
		di += eo;
		if (++i >= nm) {
			/* replace */
			di -= (eo - so);
			nbs = 0;
			for (s = repl; *s; s++) {
				ds[di++] = c = *s;
				if (c == '\\') {
					nbs++;
					continue;
				}
				if (c == '&' || (ex && c >= '0' && c <= '9')) {
					di -= ((nbs + 3) >> 1);
					j = 0;
					if (c != '&') {
						j = c - '0';
						nbs++;
					}
					if (nbs % 2) {
						ds[di++] = c;
					} else {
						n = pmatch[j].rm_eo - pmatch[j].rm_so;
						qrealloc(&ds, di + rl + n, &dssize);
						memcpy(ds + di, sp + pmatch[j].rm_so, n);
						di += n;
					}
				}
				nbs = 0;
			}
		}

		sp += eo;
		if (i == nm) break;
		if (eo == so) {
			ds[di] = *sp++;
			if (!ds[di++]) break;
		}
	}

	qrealloc(&ds, di + strlen(sp), &dssize);
	strcpy(ds + di, sp);
	setvar_p(dest, ds);
	if (re == &sreg) regfree(re);
	return i;
}

static NOINLINE int do_mktime(const char *ds)
{
	struct tm then;
	int count;

	/*memset(&then, 0, sizeof(then)); - not needed */
	then.tm_isdst = -1; /* default is unknown */

	/* manpage of mktime says these fields are ints,
	 * so we can sscanf stuff directly into them */
	count = sscanf(ds, "%u %u %u %u %u %u %d",
		&then.tm_year, &then.tm_mon, &then.tm_mday,
		&then.tm_hour, &then.tm_min, &then.tm_sec,
		&then.tm_isdst);

	if (count < 6
	 || (unsigned)then.tm_mon < 1
	 || (unsigned)then.tm_year < 1900
	) {
		return -1;
	}

	then.tm_mon -= 1;
	then.tm_year -= 1900;

	return mktime(&then);
}

static NOINLINE var *exec_builtin(node *op, var *res)
{
#define tspl (G.exec_builtin__tspl)

	int (*to_xxx)(int);
	var *tv;
	node *an[4];
	var *av[4];
	const char *as[4];
	regmatch_t pmatch[2];
	regex_t sreg, *re;
	node *spl;
	uint32_t isr, info;
	int nargs;
	time_t tt;
	char *s, *s1;
	int i, l, ll, n;

	tv = nvalloc(4);
	isr = info = op->info;
	op = op->l.n;

	av[2] = av[3] = NULL;
	for (i = 0; i < 4 && op; i++) {
		an[i] = nextarg(&op);
		if (isr & 0x09000000) av[i] = evaluate(an[i], &tv[i]);
		if (isr & 0x08000000) as[i] = getvar_s(av[i]);
		isr >>= 1;
	}

	nargs = i;
	if ((uint32_t)nargs < (info >> 30))
		syntax_error(EMSG_TOO_FEW_ARGS);

	switch (info & OPNMASK) {

	case B_a2:
#if ENABLE_FEATURE_AWK_LIBM
		setvar_i(res, atan2(getvar_i(av[0]), getvar_i(av[1])));
#else
		syntax_error(EMSG_NO_MATH);
#endif
		break;

	case B_sp:
		if (nargs > 2) {
			spl = (an[2]->info & OPCLSMASK) == OC_REGEXP ?
				an[2] : mk_splitter(getvar_s(evaluate(an[2], &tv[2])), &tspl);
		} else {
			spl = &fsplitter.n;
		}

		n = awk_split(as[0], spl, &s);
		s1 = s;
		clear_array(iamarray(av[1]));
		for (i = 1; i <= n; i++)
			setari_u(av[1], i, nextword(&s1));
		free(s);
		setvar_i(res, n);
		break;

	case B_ss:
		l = strlen(as[0]);
		i = getvar_i(av[1]) - 1;
		if (i > l) i = l;
		if (i < 0) i = 0;
		n = (nargs > 2) ? getvar_i(av[2]) : l-i;
		if (n < 0) n = 0;
		s = xstrndup(as[0]+i, n);
		setvar_p(res, s);
		break;

	/* Bitwise ops must assume that operands are unsigned. GNU Awk 3.1.5:
	 * awk '{ print or(-1,1) }' gives "4.29497e+09", not "-2.xxxe+09" */
	case B_an:
		setvar_i(res, getvar_i_int(av[0]) & getvar_i_int(av[1]));
		break;

	case B_co:
		setvar_i(res, ~getvar_i_int(av[0]));
		break;

	case B_ls:
		setvar_i(res, getvar_i_int(av[0]) << getvar_i_int(av[1]));
		break;

	case B_or:
		setvar_i(res, getvar_i_int(av[0]) | getvar_i_int(av[1]));
		break;

	case B_rs:
		setvar_i(res, getvar_i_int(av[0]) >> getvar_i_int(av[1]));
		break;

	case B_xo:
		setvar_i(res, getvar_i_int(av[0]) ^ getvar_i_int(av[1]));
		break;

	case B_lo:
		to_xxx = tolower;
		goto lo_cont;

	case B_up:
		to_xxx = toupper;
 lo_cont:
		s1 = s = xstrdup(as[0]);
		while (*s1) {
			*s1 = (*to_xxx)(*s1);
			s1++;
		}
		setvar_p(res, s);
		break;

	case B_ix:
		n = 0;
		ll = strlen(as[1]);
		l = strlen(as[0]) - ll;
		if (ll > 0 && l >= 0) {
			if (!icase) {
				s = strstr(as[0], as[1]);
				if (s) n = (s - as[0]) + 1;
			} else {
				/* this piece of code is terribly slow and
				 * really should be rewritten
				 */
				for (i=0; i<=l; i++) {
					if (strncasecmp(as[0]+i, as[1], ll) == 0) {
						n = i+1;
						break;
					}
				}
			}
		}
		setvar_i(res, n);
		break;

	case B_ti:
		if (nargs > 1)
			tt = getvar_i(av[1]);
		else
			time(&tt);
		//s = (nargs > 0) ? as[0] : "%a %b %d %H:%M:%S %Z %Y";
		i = strftime(g_buf, MAXVARFMT,
			((nargs > 0) ? as[0] : "%a %b %d %H:%M:%S %Z %Y"),
			localtime(&tt));
		g_buf[i] = '\0';
		setvar_s(res, g_buf);
		break;

	case B_mt:
		setvar_i(res, do_mktime(as[0]));
		break;

	case B_ma:
		re = as_regex(an[1], &sreg);
		n = regexec(re, as[0], 1, pmatch, 0);
		if (n == 0) {
			pmatch[0].rm_so++;
			pmatch[0].rm_eo++;
		} else {
			pmatch[0].rm_so = 0;
			pmatch[0].rm_eo = -1;
		}
		setvar_i(newvar("RSTART"), pmatch[0].rm_so);
		setvar_i(newvar("RLENGTH"), pmatch[0].rm_eo - pmatch[0].rm_so);
		setvar_i(res, pmatch[0].rm_so);
		if (re == &sreg) regfree(re);
		break;

	case B_ge:
		awk_sub(an[0], as[1], getvar_i(av[2]), av[3], res, TRUE);
		break;

	case B_gs:
		setvar_i(res, awk_sub(an[0], as[1], 0, av[2], av[2], FALSE));
		break;

	case B_su:
		setvar_i(res, awk_sub(an[0], as[1], 1, av[2], av[2], FALSE));
		break;
	}

	nvfree(tv);
	return res;
#undef tspl
}

/*
 * Evaluate node - the heart of the program. Supplied with subtree
 * and place where to store result. returns ptr to result.
 */
#define XC(n) ((n) >> 8)

static var *evaluate(node *op, var *res)
{
/* This procedure is recursive so we should count every byte */
#define fnargs (G.evaluate__fnargs)
/* seed is initialized to 1 */
#define seed   (G.evaluate__seed)
#define	sreg   (G.evaluate__sreg)

	node *op1;
	var *v1;
	union {
		var *v;
		const char *s;
		double d;
		int i;
	} L, R;
	uint32_t opinfo;
	int opn;
	union {
		char *s;
		rstream *rsm;
		FILE *F;
		var *v;
		regex_t *re;
		uint32_t info;
	} X;

	if (!op)
		return setvar_s(res, NULL);

	v1 = nvalloc(2);

	while (op) {
		opinfo = op->info;
		opn = (opinfo & OPNMASK);
		g_lineno = op->lineno;

		/* execute inevitable things */
		op1 = op->l.n;
		if (opinfo & OF_RES1) X.v = L.v = evaluate(op1, v1);
		if (opinfo & OF_RES2) R.v = evaluate(op->r.n, v1+1);
		if (opinfo & OF_STR1) L.s = getvar_s(L.v);
		if (opinfo & OF_STR2) R.s = getvar_s(R.v);
		if (opinfo & OF_NUM1) L.d = getvar_i(L.v);

		switch (XC(opinfo & OPCLSMASK)) {

		/* -- iterative node type -- */

		/* test pattern */
		case XC( OC_TEST ):
			if ((op1->info & OPCLSMASK) == OC_COMMA) {
				/* it's range pattern */
				if ((opinfo & OF_CHECKED) || ptest(op1->l.n)) {
					op->info |= OF_CHECKED;
					if (ptest(op1->r.n))
						op->info &= ~OF_CHECKED;

					op = op->a.n;
				} else {
					op = op->r.n;
				}
			} else {
				op = (ptest(op1)) ? op->a.n : op->r.n;
			}
			break;

		/* just evaluate an expression, also used as unconditional jump */
		case XC( OC_EXEC ):
			break;

		/* branch, used in if-else and various loops */
		case XC( OC_BR ):
			op = istrue(L.v) ? op->a.n : op->r.n;
			break;

		/* initialize for-in loop */
		case XC( OC_WALKINIT ):
			hashwalk_init(L.v, iamarray(R.v));
			break;

		/* get next array item */
		case XC( OC_WALKNEXT ):
			op = hashwalk_next(L.v) ? op->a.n : op->r.n;
			break;

		case XC( OC_PRINT ):
		case XC( OC_PRINTF ):
			X.F = stdout;
			if (op->r.n) {
				X.rsm = newfile(R.s);
				if (!X.rsm->F) {
					if (opn == '|') {
						X.rsm->F = popen(R.s, "w");
						if (X.rsm->F == NULL)
							bb_perror_msg_and_die("popen");
						X.rsm->is_pipe = 1;
					} else {
						X.rsm->F = xfopen(R.s, opn=='w' ? "w" : "a");
					}
				}
				X.F = X.rsm->F;
			}

			if ((opinfo & OPCLSMASK) == OC_PRINT) {
				if (!op1) {
					fputs(getvar_s(intvar[F0]), X.F);
				} else {
					while (op1) {
						L.v = evaluate(nextarg(&op1), v1);
						if (L.v->type & VF_NUMBER) {
							fmt_num(g_buf, MAXVARFMT, getvar_s(intvar[OFMT]),
									getvar_i(L.v), TRUE);
							fputs(g_buf, X.F);
						} else {
							fputs(getvar_s(L.v), X.F);
						}

						if (op1) fputs(getvar_s(intvar[OFS]), X.F);
					}
				}
				fputs(getvar_s(intvar[ORS]), X.F);

			} else {	/* OC_PRINTF */
				L.s = awk_printf(op1);
				fputs(L.s, X.F);
				free((char*)L.s);
			}
			fflush(X.F);
			break;

		case XC( OC_DELETE ):
			X.info = op1->info & OPCLSMASK;
			if (X.info == OC_VAR) {
				R.v = op1->l.v;
			} else if (X.info == OC_FNARG) {
				R.v = &fnargs[op1->l.i];
			} else {
				syntax_error(EMSG_NOT_ARRAY);
			}

			if (op1->r.n) {
				clrvar(L.v);
				L.s = getvar_s(evaluate(op1->r.n, v1));
				hash_remove(iamarray(R.v), L.s);
			} else {
				clear_array(iamarray(R.v));
			}
			break;

		case XC( OC_NEWSOURCE ):
			g_progname = op->l.s;
			break;

		case XC( OC_RETURN ):
			copyvar(res, L.v);
			break;

		case XC( OC_NEXTFILE ):
			nextfile = TRUE;
		case XC( OC_NEXT ):
			nextrec = TRUE;
		case XC( OC_DONE ):
			clrvar(res);
			break;

		case XC( OC_EXIT ):
			awk_exit(L.d);

		/* -- recursive node type -- */

		case XC( OC_VAR ):
			L.v = op->l.v;
			if (L.v == intvar[NF])
				split_f0();
			goto v_cont;

		case XC( OC_FNARG ):
			L.v = &fnargs[op->l.i];
 v_cont:
			res = op->r.n ? findvar(iamarray(L.v), R.s) : L.v;
			break;

		case XC( OC_IN ):
			setvar_i(res, hash_search(iamarray(R.v), L.s) ? 1 : 0);
			break;

		case XC( OC_REGEXP ):
			op1 = op;
			L.s = getvar_s(intvar[F0]);
			goto re_cont;

		case XC( OC_MATCH ):
			op1 = op->r.n;
 re_cont:
			X.re = as_regex(op1, &sreg);
			R.i = regexec(X.re, L.s, 0, NULL, 0);
			if (X.re == &sreg) regfree(X.re);
			setvar_i(res, (R.i == 0 ? 1 : 0) ^ (opn == '!' ? 1 : 0));
			break;

		case XC( OC_MOVE ):
			/* if source is a temporary string, jusk relink it to dest */
			if (R.v == v1+1 && R.v->string) {
				res = setvar_p(L.v, R.v->string);
				R.v->string = NULL;
			} else {
				res = copyvar(L.v, R.v);
			}
			break;

		case XC( OC_TERNARY ):
			if ((op->r.n->info & OPCLSMASK) != OC_COLON)
				syntax_error(EMSG_POSSIBLE_ERROR);
			res = evaluate(istrue(L.v) ? op->r.n->l.n : op->r.n->r.n, res);
			break;

		case XC( OC_FUNC ):
			if (!op->r.f->body.first)
				syntax_error(EMSG_UNDEF_FUNC);

			X.v = R.v = nvalloc(op->r.f->nargs+1);
			while (op1) {
				L.v = evaluate(nextarg(&op1), v1);
				copyvar(R.v, L.v);
				R.v->type |= VF_CHILD;
				R.v->x.parent = L.v;
				if (++R.v - X.v >= op->r.f->nargs)
					break;
			}

			R.v = fnargs;
			fnargs = X.v;

			L.s = g_progname;
			res = evaluate(op->r.f->body.first, res);
			g_progname = L.s;

			nvfree(fnargs);
			fnargs = R.v;
			break;

		case XC( OC_GETLINE ):
		case XC( OC_PGETLINE ):
			if (op1) {
				X.rsm = newfile(L.s);
				if (!X.rsm->F) {
					if ((opinfo & OPCLSMASK) == OC_PGETLINE) {
						X.rsm->F = popen(L.s, "r");
						X.rsm->is_pipe = TRUE;
					} else {
						X.rsm->F = fopen_for_read(L.s);		/* not xfopen! */
					}
				}
			} else {
				if (!iF) iF = next_input_file();
				X.rsm = iF;
			}

			if (!X.rsm->F) {
				setvar_i(intvar[ERRNO], errno);
				setvar_i(res, -1);
				break;
			}

			if (!op->r.n)
				R.v = intvar[F0];

			L.i = awk_getline(X.rsm, R.v);
			if (L.i > 0) {
				if (!op1) {
					incvar(intvar[FNR]);
					incvar(intvar[NR]);
				}
			}
			setvar_i(res, L.i);
			break;

		/* simple builtins */
		case XC( OC_FBLTIN ):
			switch (opn) {

			case F_in:
				R.d = (int)L.d;
				break;

			case F_rn:
				R.d = (double)rand() / (double)RAND_MAX;
				break;
#if ENABLE_FEATURE_AWK_LIBM
			case F_co:
				R.d = cos(L.d);
				break;

			case F_ex:
				R.d = exp(L.d);
				break;

			case F_lg:
				R.d = log(L.d);
				break;

			case F_si:
				R.d = sin(L.d);
				break;

			case F_sq:
				R.d = sqrt(L.d);
				break;
#else
			case F_co:
			case F_ex:
			case F_lg:
			case F_si:
			case F_sq:
				syntax_error(EMSG_NO_MATH);
				break;
#endif
			case F_sr:
				R.d = (double)seed;
				seed = op1 ? (unsigned)L.d : (unsigned)time(NULL);
				srand(seed);
				break;

			case F_ti:
				R.d = time(NULL);
				break;

			case F_le:
				if (!op1)
					L.s = getvar_s(intvar[F0]);
				R.d = strlen(L.s);
				break;

			case F_sy:
				fflush(NULL);
				R.d = (ENABLE_FEATURE_ALLOW_EXEC && L.s && *L.s)
						? (system(L.s) >> 8) : 0;
				break;

			case F_ff:
				if (!op1)
					fflush(stdout);
				else {
					if (L.s && *L.s) {
						X.rsm = newfile(L.s);
						fflush(X.rsm->F);
					} else {
						fflush(NULL);
					}
				}
				break;

			case F_cl:
				X.rsm = (rstream *)hash_search(fdhash, L.s);
				if (X.rsm) {
					R.i = X.rsm->is_pipe ? pclose(X.rsm->F) : fclose(X.rsm->F);
					free(X.rsm->buffer);
					hash_remove(fdhash, L.s);
				}
				if (R.i != 0)
					setvar_i(intvar[ERRNO], errno);
				R.d = (double)R.i;
				break;
			}
			setvar_i(res, R.d);
			break;

		case XC( OC_BUILTIN ):
			res = exec_builtin(op, res);
			break;

		case XC( OC_SPRINTF ):
			setvar_p(res, awk_printf(op1));
			break;

		case XC( OC_UNARY ):
			X.v = R.v;
			L.d = R.d = getvar_i(R.v);
			switch (opn) {
			case 'P':
				L.d = ++R.d;
				goto r_op_change;
			case 'p':
				R.d++;
				goto r_op_change;
			case 'M':
				L.d = --R.d;
				goto r_op_change;
			case 'm':
				R.d--;
				goto r_op_change;
			case '!':
				L.d = istrue(X.v) ? 0 : 1;
				break;
			case '-':
				L.d = -R.d;
				break;
 r_op_change:
				setvar_i(X.v, R.d);
			}
			setvar_i(res, L.d);
			break;

		case XC( OC_FIELD ):
			R.i = (int)getvar_i(R.v);
			if (R.i == 0) {
				res = intvar[F0];
			} else {
				split_f0();
				if (R.i > nfields)
					fsrealloc(R.i);
				res = &Fields[R.i - 1];
			}
			break;

		/* concatenation (" ") and index joining (",") */
		case XC( OC_CONCAT ):
		case XC( OC_COMMA ):
			opn = strlen(L.s) + strlen(R.s) + 2;
			X.s = xmalloc(opn);
			strcpy(X.s, L.s);
			if ((opinfo & OPCLSMASK) == OC_COMMA) {
				L.s = getvar_s(intvar[SUBSEP]);
				X.s = xrealloc(X.s, opn + strlen(L.s));
				strcat(X.s, L.s);
			}
			strcat(X.s, R.s);
			setvar_p(res, X.s);
			break;

		case XC( OC_LAND ):
			setvar_i(res, istrue(L.v) ? ptest(op->r.n) : 0);
			break;

		case XC( OC_LOR ):
			setvar_i(res, istrue(L.v) ? 1 : ptest(op->r.n));
			break;

		case XC( OC_BINARY ):
		case XC( OC_REPLACE ):
			R.d = getvar_i(R.v);
			switch (opn) {
			case '+':
				L.d += R.d;
				break;
			case '-':
				L.d -= R.d;
				break;
			case '*':
				L.d *= R.d;
				break;
			case '/':
				if (R.d == 0) syntax_error(EMSG_DIV_BY_ZERO);
				L.d /= R.d;
				break;
			case '&':
#if ENABLE_FEATURE_AWK_LIBM
				L.d = pow(L.d, R.d);
#else
				syntax_error(EMSG_NO_MATH);
#endif
				break;
			case '%':
				if (R.d == 0) syntax_error(EMSG_DIV_BY_ZERO);
				L.d -= (int)(L.d / R.d) * R.d;
				break;
			}
			res = setvar_i(((opinfo & OPCLSMASK) == OC_BINARY) ? res : X.v, L.d);
			break;

		case XC( OC_COMPARE ):
			if (is_numeric(L.v) && is_numeric(R.v)) {
				L.d = getvar_i(L.v) - getvar_i(R.v);
			} else {
				L.s = getvar_s(L.v);
				R.s = getvar_s(R.v);
				L.d = icase ? strcasecmp(L.s, R.s) : strcmp(L.s, R.s);
			}
			switch (opn & 0xfe) {
			case 0:
				R.i = (L.d > 0);
				break;
			case 2:
				R.i = (L.d >= 0);
				break;
			case 4:
				R.i = (L.d == 0);
				break;
			}
			setvar_i(res, (opn & 0x1 ? R.i : !R.i) ? 1 : 0);
			break;

		default:
			syntax_error(EMSG_POSSIBLE_ERROR);
		}
		if ((opinfo & OPCLSMASK) <= SHIFT_TIL_THIS)
			op = op->a.n;
		if ((opinfo & OPCLSMASK) >= RECUR_FROM_THIS)
			break;
		if (nextrec)
			break;
	}
	nvfree(v1);
	return res;
#undef fnargs
#undef seed
#undef sreg
}


/* -------- main & co. -------- */

static int awk_exit(int r)
{
	var tv;
	unsigned i;
	hash_item *hi;

	zero_out_var(&tv);

	if (!exiting) {
		exiting = TRUE;
		nextrec = FALSE;
		evaluate(endseq.first, &tv);
	}

	/* waiting for children */
	for (i = 0; i < fdhash->csize; i++) {
		hi = fdhash->items[i];
		while (hi) {
			if (hi->data.rs.F && hi->data.rs.is_pipe)
				pclose(hi->data.rs.F);
			hi = hi->next;
		}
	}

	exit(r);
}

/* if expr looks like "var=value", perform assignment and return 1,
 * otherwise return 0 */
static int is_assignment(const char *expr)
{
	char *exprc, *s, *s0, *s1;

	exprc = xstrdup(expr);
	if (!isalnum_(*exprc) || (s = strchr(exprc, '=')) == NULL) {
		free(exprc);
		return FALSE;
	}

	*(s++) = '\0';
	s0 = s1 = s;
	while (*s)
		*(s1++) = nextchar(&s);

	*s1 = '\0';
	setvar_u(newvar(exprc), s0);
	free(exprc);
	return TRUE;
}

/* switch to next input file */
static rstream *next_input_file(void)
{
#define rsm          (G.next_input_file__rsm)
#define files_happen (G.next_input_file__files_happen)

	FILE *F = NULL;
	const char *fname, *ind;

	if (rsm.F) fclose(rsm.F);
	rsm.F = NULL;
	rsm.pos = rsm.adv = 0;

	do {
		if (getvar_i(intvar[ARGIND])+1 >= getvar_i(intvar[ARGC])) {
			if (files_happen)
				return NULL;
			fname = "-";
			F = stdin;
		} else {
			ind = getvar_s(incvar(intvar[ARGIND]));
			fname = getvar_s(findvar(iamarray(intvar[ARGV]), ind));
			if (fname && *fname && !is_assignment(fname))
				F = xfopen_stdin(fname);
		}
	} while (!F);

	files_happen = TRUE;
	setvar_s(intvar[FILENAME], fname);
	rsm.F = F;
	return &rsm;
#undef rsm
#undef files_happen
}

int awk_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int awk_main(int argc, char **argv)
{
	unsigned opt;
	char *opt_F, *opt_W;
	llist_t *list_v = NULL;
	llist_t *list_f = NULL;
	int i, j;
	var *v;
	var tv;
	char **envp;
	char *vnames = (char *)vNames; /* cheat */
	char *vvalues = (char *)vValues;

	INIT_G();

	/* Undo busybox.c, or else strtod may eat ','! This breaks parsing:
	 * $1,$2 == '$1,' '$2', NOT '$1' ',' '$2' */
	if (ENABLE_LOCALE_SUPPORT)
		setlocale(LC_NUMERIC, "C");

	zero_out_var(&tv);

	/* allocate global buffer */
	g_buf = xmalloc(MAXVARFMT + 1);

	vhash = hash_init();
	ahash = hash_init();
	fdhash = hash_init();
	fnhash = hash_init();

	/* initialize variables */
	for (i = 0; *vnames; i++) {
		intvar[i] = v = newvar(nextword(&vnames));
		if (*vvalues != '\377')
			setvar_s(v, nextword(&vvalues));
		else
			setvar_i(v, 0);

		if (*vnames == '*') {
			v->type |= VF_SPECIAL;
			vnames++;
		}
	}

	handle_special(intvar[FS]);
	handle_special(intvar[RS]);

	newfile("/dev/stdin")->F = stdin;
	newfile("/dev/stdout")->F = stdout;
	newfile("/dev/stderr")->F = stderr;

	/* Huh, people report that sometimes environ is NULL. Oh well. */
	if (environ) for (envp = environ; *envp; envp++) {
		/* environ is writable, thus we don't strdup it needlessly */
		char *s = *envp;
		char *s1 = strchr(s, '=');
		if (s1) {
			*s1 = '\0';
			/* Both findvar and setvar_u take const char*
			 * as 2nd arg -> environment is not trashed */
			setvar_u(findvar(iamarray(intvar[ENVIRON]), s), s1 + 1);
			*s1 = '=';
		}
	}
	opt_complementary = "v::f::"; /* -v and -f can occur multiple times */
	opt = getopt32(argv, "F:v:f:W:", &opt_F, &list_v, &list_f, &opt_W);
	argv += optind;
	argc -= optind;
	if (opt & 0x1)
		setvar_s(intvar[FS], opt_F); // -F
	while (list_v) { /* -v */
		if (!is_assignment(llist_pop(&list_v)))
			bb_show_usage();
	}
	if (list_f) { /* -f */
		do {
			char *s = NULL;
			FILE *from_file;

			g_progname = llist_pop(&list_f);
			from_file = xfopen_stdin(g_progname);
			/* one byte is reserved for some trick in next_token */
			for (i = j = 1; j > 0; i += j) {
				s = xrealloc(s, i + 4096);
				j = fread(s + i, 1, 4094, from_file);
			}
			s[i] = '\0';
			fclose(from_file);
			parse_program(s + 1);
			free(s);
		} while (list_f);
		argc++;
	} else { // no -f: take program from 1st parameter
		if (!argc)
			bb_show_usage();
		g_progname = "cmd. line";
		parse_program(*argv++);
	}
	if (opt & 0x8) // -W
		bb_error_msg("warning: unrecognized option '-W %s' ignored", opt_W);

	/* fill in ARGV array */
	setvar_i(intvar[ARGC], argc);
	setari_u(intvar[ARGV], 0, "awk");
	i = 0;
	while (*argv)
		setari_u(intvar[ARGV], ++i, *argv++);

	evaluate(beginseq.first, &tv);
	if (!mainseq.first && !endseq.first)
		awk_exit(EXIT_SUCCESS);

	/* input file could already be opened in BEGIN block */
	if (!iF) iF = next_input_file();

	/* passing through input files */
	while (iF) {
		nextfile = FALSE;
		setvar_i(intvar[FNR], 0);

		while ((i = awk_getline(iF, intvar[F0])) > 0) {
			nextrec = FALSE;
			incvar(intvar[NR]);
			incvar(intvar[FNR]);
			evaluate(mainseq.first, &tv);

			if (nextfile)
				break;
		}

		if (i < 0)
			syntax_error(strerror(errno));

		iF = next_input_file();
	}

	awk_exit(EXIT_SUCCESS);
	/*return 0;*/
}