xref: /freebsd/bin/sh/expand.c (revision c39d3320ab681401a3644401928e8be40f13afd9)

/*-
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1997-2005
 *	Herbert Xu <herbert@gondor.apana.org.au>.  All rights reserved.
 * Copyright (c) 2010-2015
 *	Jilles Tjoelker <jilles@stack.nl>.  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. 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.
 */

#ifndef lint
#if 0
static char sccsid[] = "@(#)expand.c	8.5 (Berkeley) 5/15/95";
#endif
#endif /* not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/types.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <dirent.h>
#include <errno.h>
#include <inttypes.h>
#include <limits.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <wchar.h>
#include <wctype.h>

/*
 * Routines to expand arguments to commands.  We have to deal with
 * backquotes, shell variables, and file metacharacters.
 */

#include "shell.h"
#include "main.h"
#include "nodes.h"
#include "eval.h"
#include "expand.h"
#include "syntax.h"
#include "parser.h"
#include "jobs.h"
#include "options.h"
#include "var.h"
#include "input.h"
#include "output.h"
#include "memalloc.h"
#include "error.h"
#include "mystring.h"
#include "arith.h"
#include "show.h"
#include "builtins.h"

enum wordstate { WORD_IDLE, WORD_WS_DELIMITED, WORD_QUOTEMARK };

struct worddest {
	struct arglist *list;
	enum wordstate state;
};

static char *expdest;			/* output of current string */

static const char *argstr(const char *, struct nodelist **restrict, int,
    struct worddest *);
static const char *exptilde(const char *, int);
static const char *expari(const char *, struct nodelist **restrict, int,
    struct worddest *);
static void expbackq(union node *, int, int, struct worddest *);
static const char *subevalvar_trim(const char *, struct nodelist **restrict,
    int, int, int);
static const char *subevalvar_misc(const char *, struct nodelist **restrict,
    const char *, int, int, int);
static const char *evalvar(const char *, struct nodelist **restrict, int,
    struct worddest *);
static int varisset(const char *, int);
static void strtodest(const char *, int, int, int, struct worddest *);
static void reprocess(int, int, int, int, struct worddest *);
static void varvalue(const char *, int, int, int, struct worddest *);
static void expandmeta(char *, struct arglist *);
static void expmeta(char *, char *, struct arglist *);
static int expsortcmp(const void *, const void *);
static int patmatch(const char *, const char *);
static void cvtnum(int, char *);
static int collate_range_cmp(wchar_t, wchar_t);

void
emptyarglist(struct arglist *list)
{

	list->args = list->smallarg;
	list->count = 0;
	list->capacity = sizeof(list->smallarg) / sizeof(list->smallarg[0]);
}

void
appendarglist(struct arglist *list, char *str)
{
	char **newargs;
	int newcapacity;

	if (list->count >= list->capacity) {
		newcapacity = list->capacity * 2;
		if (newcapacity < 16)
			newcapacity = 16;
		if (newcapacity > INT_MAX / (int)sizeof(newargs[0]))
			error("Too many entries in arglist");
		newargs = stalloc(newcapacity * sizeof(newargs[0]));
		memcpy(newargs, list->args, list->count * sizeof(newargs[0]));
		list->args = newargs;
		list->capacity = newcapacity;
	}
	list->args[list->count++] = str;
}

static int
collate_range_cmp(wchar_t c1, wchar_t c2)
{
	wchar_t s1[2], s2[2];

	s1[0] = c1;
	s1[1] = L'\0';
	s2[0] = c2;
	s2[1] = L'\0';
	return (wcscoll(s1, s2));
}

static char *
stputs_quotes(const char *data, const char *syntax, char *p)
{
	while (*data) {
		CHECKSTRSPACE(2, p);
		if (syntax[(int)*data] == CCTL)
			USTPUTC(CTLESC, p);
		USTPUTC(*data++, p);
	}
	return (p);
}
#define STPUTS_QUOTES(data, syntax, p) p = stputs_quotes((data), syntax, p)

static char *
nextword(char c, int flag, char *p, struct worddest *dst)
{
	int is_ws;

	is_ws = c == '\t' || c == '\n' || c == ' ';
	if (p != stackblock() || (is_ws ? dst->state == WORD_QUOTEMARK :
	    dst->state != WORD_WS_DELIMITED) || c == '\0') {
		STPUTC('\0', p);
		if (flag & EXP_GLOB)
			expandmeta(grabstackstr(p), dst->list);
		else
			appendarglist(dst->list, grabstackstr(p));
		dst->state = is_ws ? WORD_WS_DELIMITED : WORD_IDLE;
	} else if (!is_ws && dst->state == WORD_WS_DELIMITED)
		dst->state = WORD_IDLE;
	/* Reserve space while the stack string is empty. */
	appendarglist(dst->list, NULL);
	dst->list->count--;
	STARTSTACKSTR(p);
	return p;
}
#define NEXTWORD(c, flag, p, dstlist) p = nextword(c, flag, p, dstlist)

static char *
stputs_split(const char *data, const char *syntax, int flag, char *p,
    struct worddest *dst)
{
	const char *ifs;
	char c;

	ifs = ifsset() ? ifsval() : " \t\n";
	while (*data) {
		CHECKSTRSPACE(2, p);
		c = *data++;
		if (strchr(ifs, c) != NULL) {
			NEXTWORD(c, flag, p, dst);
			continue;
		}
		if (flag & EXP_GLOB && syntax[(int)c] == CCTL)
			USTPUTC(CTLESC, p);
		USTPUTC(c, p);
	}
	return (p);
}
#define STPUTS_SPLIT(data, syntax, flag, p, dst) p = stputs_split((data), syntax, flag, p, dst)

/*
 * Perform expansions on an argument, placing the resulting list of arguments
 * in arglist.  Parameter expansion, command substitution and arithmetic
 * expansion are always performed; additional expansions can be requested
 * via flag (EXP_*).
 * The result is left in the stack string.
 * When arglist is NULL, perform here document expansion.
 *
 * Caution: this function uses global state and is not reentrant.
 * However, a new invocation after an interrupted invocation is safe
 * and will reset the global state for the new call.
 */
void
expandarg(union node *arg, struct arglist *arglist, int flag)
{
	struct worddest exparg;
	struct nodelist *argbackq;

	if (fflag)
		flag &= ~EXP_GLOB;
	argbackq = arg->narg.backquote;
	exparg.list = arglist;
	exparg.state = WORD_IDLE;
	STARTSTACKSTR(expdest);
	argstr(arg->narg.text, &argbackq, flag, &exparg);
	if (arglist == NULL) {
		STACKSTRNUL(expdest);
		return;			/* here document expanded */
	}
	if ((flag & EXP_SPLIT) == 0 || expdest != stackblock() ||
	    exparg.state == WORD_QUOTEMARK) {
		STPUTC('\0', expdest);
		if (flag & EXP_SPLIT) {
			if (flag & EXP_GLOB)
				expandmeta(grabstackstr(expdest), exparg.list);
			else
				appendarglist(exparg.list, grabstackstr(expdest));
		}
	}
	if ((flag & EXP_SPLIT) == 0)
		appendarglist(arglist, grabstackstr(expdest));
}



/*
 * Perform parameter expansion, command substitution and arithmetic
 * expansion, and tilde expansion if requested via EXP_TILDE/EXP_VARTILDE.
 * Processing ends at a CTLENDVAR or CTLENDARI character as well as '\0'.
 * This is used to expand word in ${var+word} etc.
 * If EXP_GLOB or EXP_CASE are set, keep and/or generate CTLESC
 * characters to allow for further processing.
 *
 * If EXP_SPLIT is set, dst receives any complete words produced.
 */
static const char *
argstr(const char *p, struct nodelist **restrict argbackq, int flag,
    struct worddest *dst)
{
	char c;
	int quotes = flag & (EXP_GLOB | EXP_CASE);	/* do CTLESC */
	int firsteq = 1;
	int split_lit;
	int lit_quoted;

	split_lit = flag & EXP_SPLIT_LIT;
	lit_quoted = flag & EXP_LIT_QUOTED;
	flag &= ~(EXP_SPLIT_LIT | EXP_LIT_QUOTED);
	if (*p == '~' && (flag & (EXP_TILDE | EXP_VARTILDE)))
		p = exptilde(p, flag);
	for (;;) {
		CHECKSTRSPACE(2, expdest);
		switch (c = *p++) {
		case '\0':
			return (p - 1);
		case CTLENDVAR:
		case CTLENDARI:
			return (p);
		case CTLQUOTEMARK:
			lit_quoted = 1;
			/* "$@" syntax adherence hack */
			if (p[0] == CTLVAR && (p[1] & VSQUOTE) != 0 &&
			    p[2] == '@' && p[3] == '=')
				break;
			if ((flag & EXP_SPLIT) != 0 && expdest == stackblock())
				dst->state = WORD_QUOTEMARK;
			break;
		case CTLQUOTEEND:
			lit_quoted = 0;
			break;
		case CTLESC:
			c = *p++;
			if (split_lit && !lit_quoted &&
			    strchr(ifsset() ? ifsval() : " \t\n", c) != NULL) {
				NEXTWORD(c, flag, expdest, dst);
				break;
			}
			if (quotes)
				USTPUTC(CTLESC, expdest);
			USTPUTC(c, expdest);
			break;
		case CTLVAR:
			p = evalvar(p, argbackq, flag, dst);
			break;
		case CTLBACKQ:
		case CTLBACKQ|CTLQUOTE:
			expbackq((*argbackq)->n, c & CTLQUOTE, flag, dst);
			*argbackq = (*argbackq)->next;
			break;
		case CTLARI:
			p = expari(p, argbackq, flag, dst);
			break;
		case ':':
		case '=':
			/*
			 * sort of a hack - expand tildes in variable
			 * assignments (after the first '=' and after ':'s).
			 */
			if (split_lit && !lit_quoted &&
			    strchr(ifsset() ? ifsval() : " \t\n", c) != NULL) {
				NEXTWORD(c, flag, expdest, dst);
				break;
			}
			USTPUTC(c, expdest);
			if (flag & EXP_VARTILDE && *p == '~' &&
			    (c != '=' || firsteq)) {
				if (c == '=')
					firsteq = 0;
				p = exptilde(p, flag);
			}
			break;
		default:
			if (split_lit && !lit_quoted &&
			    strchr(ifsset() ? ifsval() : " \t\n", c) != NULL) {
				NEXTWORD(c, flag, expdest, dst);
				break;
			}
			USTPUTC(c, expdest);
		}
	}
}

/*
 * Perform tilde expansion, placing the result in the stack string and
 * returning the next position in the input string to process.
 */
static const char *
exptilde(const char *p, int flag)
{
	char c;
	const char *startp = p;
	const char *user;
	struct passwd *pw;
	char *home;
	int len;

	for (;;) {
		c = *p;
		switch(c) {
		case CTLESC: /* This means CTL* are always considered quoted. */
		case CTLVAR:
		case CTLBACKQ:
		case CTLBACKQ | CTLQUOTE:
		case CTLARI:
		case CTLENDARI:
		case CTLQUOTEMARK:
			return (startp);
		case ':':
			if ((flag & EXP_VARTILDE) == 0)
				break;
			/* FALLTHROUGH */
		case '\0':
		case '/':
		case CTLENDVAR:
			len = p - startp - 1;
			STPUTBIN(startp + 1, len, expdest);
			STACKSTRNUL(expdest);
			user = expdest - len;
			if (*user == '\0') {
				home = lookupvar("HOME");
			} else {
				pw = getpwnam(user);
				home = pw != NULL ? pw->pw_dir : NULL;
			}
			STADJUST(-len, expdest);
			if (home == NULL || *home == '\0')
				return (startp);
			strtodest(home, flag, VSNORMAL, 1, NULL);
			return (p);
		}
		p++;
	}
}


/*
 * Expand arithmetic expression.
 */
static const char *
expari(const char *p, struct nodelist **restrict argbackq, int flag,
    struct worddest *dst)
{
	char *q, *start;
	arith_t result;
	int begoff;
	int quoted;
	int adj;

	quoted = *p++ == '"';
	begoff = expdest - stackblock();
	p = argstr(p, argbackq, 0, NULL);
	STPUTC('\0', expdest);
	start = stackblock() + begoff;

	q = grabstackstr(expdest);
	result = arith(start);
	ungrabstackstr(q, expdest);

	start = stackblock() + begoff;
	adj = start - expdest;
	STADJUST(adj, expdest);

	CHECKSTRSPACE((int)(DIGITS(result) + 1), expdest);
	fmtstr(expdest, DIGITS(result), ARITH_FORMAT_STR, result);
	adj = strlen(expdest);
	STADJUST(adj, expdest);
	if (!quoted)
		reprocess(expdest - adj - stackblock(), flag, VSNORMAL, 0, dst);
	return p;
}


/*
 * Perform command substitution.
 */
static void
expbackq(union node *cmd, int quoted, int flag, struct worddest *dst)
{
	struct backcmd in;
	int i;
	char buf[128];
	char *p;
	char *dest = expdest;
	char lastc;
	char const *syntax = quoted? DQSYNTAX : BASESYNTAX;
	int quotes = flag & (EXP_GLOB | EXP_CASE);
	size_t nnl;
	const char *ifs;

	INTOFF;
	p = grabstackstr(dest);
	evalbackcmd(cmd, &in);
	ungrabstackstr(p, dest);

	p = in.buf;
	nnl = 0;
	if (!quoted && flag & EXP_SPLIT)
		ifs = ifsset() ? ifsval() : " \t\n";
	else
		ifs = "";
	/* Don't copy trailing newlines */
	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')
			continue;
		if (lastc == '\n') {
			nnl++;
		} else {
			if (nnl > 0) {
				if (strchr(ifs, '\n') != NULL) {
					NEXTWORD('\n', flag, dest, dst);
					nnl = 0;
				} else {
					CHECKSTRSPACE(nnl + 2, dest);
					while (nnl > 0) {
						nnl--;
						USTPUTC('\n', dest);
					}
				}
			}
			if (strchr(ifs, lastc) != NULL)
				NEXTWORD(lastc, flag, dest, dst);
			else {
				CHECKSTRSPACE(2, dest);
				if (quotes && syntax[(int)lastc] == CCTL)
					USTPUTC(CTLESC, dest);
				USTPUTC(lastc, dest);
			}
		}
	}

	if (in.fd >= 0)
		close(in.fd);
	if (in.buf)
		ckfree(in.buf);
	if (in.jp) {
		p = grabstackstr(dest);
		exitstatus = waitforjob(in.jp, (int *)NULL);
		ungrabstackstr(p, dest);
	}
	TRACE(("expbackq: done\n"));
	expdest = dest;
	INTON;
}



static void
recordleft(const char *str, const char *loc, char *startp)
{
	int amount;

	amount = ((str - 1) - (loc - startp)) - expdest;
	STADJUST(amount, expdest);
	while (loc != str - 1)
		*startp++ = *loc++;
}

static const char *
subevalvar_trim(const char *p, struct nodelist **restrict argbackq, int strloc,
    int subtype, int startloc)
{
	char *startp;
	char *loc = NULL;
	char *str;
	int c = 0;
	int amount;

	p = argstr(p, argbackq, EXP_CASE | EXP_TILDE, NULL);
	STACKSTRNUL(expdest);
	startp = stackblock() + startloc;
	str = stackblock() + strloc;

	switch (subtype) {
	case VSTRIMLEFT:
		for (loc = startp; loc < str; loc++) {
			c = *loc;
			*loc = '\0';
			if (patmatch(str, startp)) {
				*loc = c;
				recordleft(str, loc, startp);
				return p;
			}
			*loc = c;
		}
		break;

	case VSTRIMLEFTMAX:
		for (loc = str - 1; loc >= startp;) {
			c = *loc;
			*loc = '\0';
			if (patmatch(str, startp)) {
				*loc = c;
				recordleft(str, loc, startp);
				return p;
			}
			*loc = c;
			loc--;
		}
		break;

	case VSTRIMRIGHT:
		for (loc = str - 1; loc >= startp;) {
			if (patmatch(str, loc)) {
				amount = loc - expdest;
				STADJUST(amount, expdest);
				return p;
			}
			loc--;
		}
		break;

	case VSTRIMRIGHTMAX:
		for (loc = startp; loc < str - 1; loc++) {
			if (patmatch(str, loc)) {
				amount = loc - expdest;
				STADJUST(amount, expdest);
				return p;
			}
		}
		break;


	default:
		abort();
	}
	amount = (expdest - stackblock() - strloc) + 1;
	STADJUST(-amount, expdest);
	return p;
}


static const char *
subevalvar_misc(const char *p, struct nodelist **restrict argbackq,
    const char *var, int subtype, int startloc, int varflags)
{
	char *startp;
	int amount;

	p = argstr(p, argbackq, EXP_TILDE, NULL);
	STACKSTRNUL(expdest);
	startp = stackblock() + startloc;

	switch (subtype) {
	case VSASSIGN:
		setvar(var, startp, 0);
		amount = startp - expdest;
		STADJUST(amount, expdest);
		return p;

	case VSQUESTION:
		if (*p != CTLENDVAR) {
			outfmt(out2, "%s\n", startp);
			error((char *)NULL);
		}
		error("%.*s: parameter %snot set", (int)(p - var - 1),
		      var, (varflags & VSNUL) ? "null or " : "");

	default:
		abort();
	}
}


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

static const char *
evalvar(const char *p, struct nodelist **restrict argbackq, int flag,
    struct worddest *dst)
{
	int subtype;
	int varflags;
	const char *var;
	const char *val;
	int patloc;
	int c;
	int set;
	int special;
	int startloc;
	int varlen;
	int varlenb;
	char buf[21];

	varflags = (unsigned char)*p++;
	subtype = varflags & VSTYPE;
	var = p;
	special = 0;
	if (! is_name(*p))
		special = 1;
	p = strchr(p, '=') + 1;
	if (varflags & VSLINENO) {
		set = 1;
		special = 1;
		val = NULL;
	} else if (special) {
		set = varisset(var, varflags & VSNUL);
		val = NULL;
	} else {
		val = bltinlookup(var, 1);
		if (val == NULL || ((varflags & VSNUL) && val[0] == '\0')) {
			val = NULL;
			set = 0;
		} else
			set = 1;
	}
	varlen = 0;
	startloc = expdest - stackblock();
	if (!set && uflag && *var != '@' && *var != '*') {
		switch (subtype) {
		case VSNORMAL:
		case VSTRIMLEFT:
		case VSTRIMLEFTMAX:
		case VSTRIMRIGHT:
		case VSTRIMRIGHTMAX:
		case VSLENGTH:
			error("%.*s: parameter not set", (int)(p - var - 1),
			    var);
		}
	}
	if (set && subtype != VSPLUS) {
		/* insert the value of the variable */
		if (special) {
			if (varflags & VSLINENO) {
				if (p - var > (ptrdiff_t)sizeof(buf))
					abort();
				memcpy(buf, var, p - var - 1);
				buf[p - var - 1] = '\0';
				strtodest(buf, flag, subtype,
				    varflags & VSQUOTE, dst);
			} else
				varvalue(var, varflags & VSQUOTE, subtype, flag,
				    dst);
			if (subtype == VSLENGTH) {
				varlenb = expdest - stackblock() - startloc;
				varlen = varlenb;
				if (localeisutf8) {
					val = stackblock() + startloc;
					for (;val != expdest; val++)
						if ((*val & 0xC0) == 0x80)
							varlen--;
				}
				STADJUST(-varlenb, expdest);
			}
		} else {
			if (subtype == VSLENGTH) {
				for (;*val; val++)
					if (!localeisutf8 ||
					    (*val & 0xC0) != 0x80)
						varlen++;
			}
			else
				strtodest(val, flag, subtype,
				    varflags & VSQUOTE, dst);
		}
	}

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

	switch (subtype) {
	case VSLENGTH:
		cvtnum(varlen, buf);
		strtodest(buf, flag, VSNORMAL, varflags & VSQUOTE, dst);
		break;

	case VSNORMAL:
		return p;

	case VSPLUS:
	case VSMINUS:
		if (!set) {
			return argstr(p, argbackq,
			    flag | (flag & EXP_SPLIT ? EXP_SPLIT_LIT : 0) |
			    (varflags & VSQUOTE ? EXP_LIT_QUOTED : 0), dst);
		}
		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();
		p = subevalvar_trim(p, argbackq, patloc, subtype, startloc);
		reprocess(startloc, flag, VSNORMAL, varflags & VSQUOTE, dst);
		if (flag & EXP_SPLIT && *var == '@' && varflags & VSQUOTE)
			dst->state = WORD_QUOTEMARK;
		return p;

	case VSASSIGN:
	case VSQUESTION:
		if (!set) {
			p = subevalvar_misc(p, argbackq, var, subtype,
			    startloc, varflags);
			/* assert(subtype == VSASSIGN); */
			val = lookupvar(var);
			strtodest(val, flag, subtype, varflags & VSQUOTE, dst);
			return p;
		}
		break;

	case VSERROR:
		c = p - var - 1;
		error("${%.*s%s}: Bad substitution", c, var,
		    (c > 0 && *p != CTLENDVAR) ? "..." : "");

	default:
		abort();
	}

	{	/* skip to end of alternative */
		int nesting = 1;
		for (;;) {
			if ((c = *p++) == CTLESC)
				p++;
			else if (c == CTLBACKQ || c == (CTLBACKQ|CTLQUOTE))
				*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(const char *name, int nulok)
{

	if (*name == '!')
		return backgndpidset();
	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;
		long num;

		errno = 0;
		num = strtol(name, NULL, 10);
		if (errno != 0 || 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;
}

static void
strtodest(const char *p, int flag, int subtype, int quoted,
    struct worddest *dst)
{
	if (subtype == VSLENGTH || subtype == VSTRIMLEFT ||
	    subtype == VSTRIMLEFTMAX || subtype == VSTRIMRIGHT ||
	    subtype == VSTRIMRIGHTMAX)
		STPUTS(p, expdest);
	else if (flag & EXP_SPLIT && !quoted && dst != NULL)
		STPUTS_SPLIT(p, BASESYNTAX, flag, expdest, dst);
	else if (flag & (EXP_GLOB | EXP_CASE))
		STPUTS_QUOTES(p, quoted ? DQSYNTAX : BASESYNTAX, expdest);
	else
		STPUTS(p, expdest);
}

static void
reprocess(int startloc, int flag, int subtype, int quoted,
    struct worddest *dst)
{
	static char *buf = NULL;
	static size_t buflen = 0;
	char *startp;
	size_t len, zpos, zlen;

	startp = stackblock() + startloc;
	len = expdest - startp;
	if (len >= SIZE_MAX / 2)
		abort();
	INTOFF;
	if (len >= buflen) {
		ckfree(buf);
		buf = NULL;
	}
	if (buflen < 128)
		buflen = 128;
	while (len >= buflen)
		buflen <<= 1;
	if (buf == NULL)
		buf = ckmalloc(buflen);
	INTON;
	memcpy(buf, startp, len);
	buf[len] = '\0';
	STADJUST(-len, expdest);
	for (zpos = 0;;) {
		zlen = strlen(buf + zpos);
		strtodest(buf + zpos, flag, subtype, quoted, dst);
		zpos += zlen + 1;
		if (zpos == len + 1)
			break;
		if (flag & EXP_SPLIT && (quoted || (zlen > 0 && zpos < len)))
			NEXTWORD('\0', flag, expdest, dst);
	}
}

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

static void
varvalue(const char *name, int quoted, int subtype, int flag,
    struct worddest *dst)
{
	int num;
	char *p;
	int i;
	int splitlater;
	char sep[2];
	char **ap;
	char buf[(NSHORTOPTS > 10 ? NSHORTOPTS : 10) + 1];

	if (subtype == VSLENGTH)
		flag &= ~EXP_FULL;
	splitlater = subtype == VSTRIMLEFT || subtype == VSTRIMLEFTMAX ||
		subtype == VSTRIMRIGHT || subtype == VSTRIMRIGHTMAX;

	switch (*name) {
	case '$':
		num = rootpid;
		break;
	case '?':
		num = oexitstatus;
		break;
	case '#':
		num = shellparam.nparam;
		break;
	case '!':
		num = backgndpidval();
		break;
	case '-':
		p = buf;
		for (i = 0 ; i < NSHORTOPTS ; i++) {
			if (optval[i])
				*p++ = optletter[i];
		}
		*p = '\0';
		strtodest(buf, flag, subtype, quoted, dst);
		return;
	case '@':
		if (flag & EXP_SPLIT && quoted) {
			for (ap = shellparam.p ; (p = *ap++) != NULL ; ) {
				strtodest(p, flag, subtype, quoted, dst);
				if (*ap) {
					if (splitlater)
						STPUTC('\0', expdest);
					else
						NEXTWORD('\0', flag, expdest,
						    dst);
				}
			}
			if (shellparam.nparam > 0)
				dst->state = WORD_QUOTEMARK;
			return;
		}
		/* FALLTHROUGH */
	case '*':
		if (ifsset())
			sep[0] = ifsval()[0];
		else
			sep[0] = ' ';
		sep[1] = '\0';
		for (ap = shellparam.p ; (p = *ap++) != NULL ; ) {
			strtodest(p, flag, subtype, quoted, dst);
			if (!*ap)
				break;
			if (sep[0])
				strtodest(sep, flag, subtype, quoted, dst);
			else if (flag & EXP_SPLIT && !quoted && **ap != '\0') {
				if (splitlater)
					STPUTC('\0', expdest);
				else
					NEXTWORD('\0', flag, expdest, dst);
			}
		}
		return;
	default:
		if (is_digit(*name)) {
			num = atoi(name);
			if (num == 0)
				p = arg0;
			else if (num > 0 && num <= shellparam.nparam)
				p = shellparam.p[num - 1];
			else
				return;
			strtodest(p, flag, subtype, quoted, dst);
		}
		return;
	}
	cvtnum(num, buf);
	strtodest(buf, flag, subtype, quoted, dst);
}



static char expdir[PATH_MAX];
#define expdir_end (expdir + sizeof(expdir))

/*
 * Perform pathname generation and remove control characters.
 * At this point, the only control characters should be CTLESC.
 * The results are stored in the list dstlist.
 */
static void
expandmeta(char *pattern, struct arglist *dstlist)
{
	char *p;
	int firstmatch;
	char c;

	firstmatch = dstlist->count;
	p = pattern;
	for (; (c = *p) != '\0'; p++) {
		/* fast check for meta chars */
		if (c == '*' || c == '?' || c == '[') {
			INTOFF;
			expmeta(expdir, pattern, dstlist);
			INTON;
			break;
		}
	}
	if (dstlist->count == firstmatch) {
		/*
		 * no matches
		 */
		rmescapes(pattern);
		appendarglist(dstlist, pattern);
	} else {
		qsort(&dstlist->args[firstmatch],
		    dstlist->count - firstmatch,
		    sizeof(dstlist->args[0]), expsortcmp);
	}
}


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

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

	metaflag = 0;
	start = name;
	for (p = name; esc = 0, *p; p += esc + 1) {
		if (*p == '*' || *p == '?')
			metaflag = 1;
		else if (*p == '[') {
			q = p + 1;
			if (*q == '!' || *q == '^')
				q++;
			for (;;) {
				if (*q == CTLESC)
					q++;
				if (*q == '/' || *q == '\0')
					break;
				if (*++q == ']') {
					metaflag = 1;
					break;
				}
			}
		} else if (*p == '\0')
			break;
		else {
			if (*p == CTLESC)
				esc++;
			if (p[esc] == '/') {
				if (metaflag)
					break;
				start = p + esc + 1;
			}
		}
	}
	if (metaflag == 0) {	/* we've reached the end of the file name */
		if (enddir != expdir)
			metaflag++;
		for (p = name ; ; p++) {
			if (*p == CTLESC)
				p++;
			*enddir++ = *p;
			if (*p == '\0')
				break;
			if (enddir == expdir_end)
				return;
		}
		if (metaflag == 0 || lstat(expdir, &statb) >= 0)
			appendarglist(arglist, stsavestr(expdir));
		return;
	}
	endname = name + (p - name);
	if (start != name) {
		p = name;
		while (p < start) {
			if (*p == CTLESC)
				p++;
			*enddir++ = *p++;
			if (enddir == expdir_end)
				return;
		}
	}
	if (enddir == expdir) {
		p = ".";
	} else if (enddir == expdir + 1 && *expdir == '/') {
		p = "/";
	} else {
		p = expdir;
		enddir[-1] = '\0';
	}
	if ((dirp = opendir(p)) == NULL)
		return;
	if (enddir != expdir)
		enddir[-1] = '/';
	if (*endname == 0) {
		atend = 1;
	} else {
		atend = 0;
		*endname = '\0';
		endname += esc + 1;
	}
	matchdot = 0;
	p = start;
	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)) {
			namlen = dp->d_namlen;
			if (enddir + namlen + 1 > expdir_end)
				continue;
			memcpy(enddir, dp->d_name, namlen + 1);
			if (atend)
				appendarglist(arglist, stsavestr(expdir));
			else {
				if (dp->d_type != DT_UNKNOWN &&
				    dp->d_type != DT_DIR &&
				    dp->d_type != DT_LNK)
					continue;
				if (enddir + namlen + 2 > expdir_end)
					continue;
				enddir[namlen] = '/';
				enddir[namlen + 1] = '\0';
				expmeta(enddir + namlen + 1, endname, arglist);
			}
		}
	}
	closedir(dirp);
	if (! atend)
		endname[-esc - 1] = esc ? CTLESC : '/';
}


static int
expsortcmp(const void *p1, const void *p2)
{
	const char *s1 = *(const char * const *)p1;
	const char *s2 = *(const char * const *)p2;

	return (strcoll(s1, s2));
}



static wchar_t
get_wc(const char **p)
{
	wchar_t c;
	int chrlen;

	chrlen = mbtowc(&c, *p, 4);
	if (chrlen == 0)
		return 0;
	else if (chrlen == -1)
		c = 0;
	else
		*p += chrlen;
	return c;
}


/*
 * See if a character matches a character class, starting at the first colon
 * of "[:class:]".
 * If a valid character class is recognized, a pointer to the next character
 * after the final closing bracket is stored into *end, otherwise a null
 * pointer is stored into *end.
 */
static int
match_charclass(const char *p, wchar_t chr, const char **end)
{
	char name[20];
	const char *nameend;
	wctype_t cclass;

	*end = NULL;
	p++;
	nameend = strstr(p, ":]");
	if (nameend == NULL || (size_t)(nameend - p) >= sizeof(name) ||
	    nameend == p)
		return 0;
	memcpy(name, p, nameend - p);
	name[nameend - p] = '\0';
	*end = nameend + 2;
	cclass = wctype(name);
	/* An unknown class matches nothing but is valid nevertheless. */
	if (cclass == 0)
		return 0;
	return iswctype(chr, cclass);
}


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

static int
patmatch(const char *pattern, const char *string)
{
	const char *p, *q, *end;
	const char *bt_p, *bt_q;
	char c;
	wchar_t wc, wc2;

	p = pattern;
	q = string;
	bt_p = NULL;
	bt_q = NULL;
	for (;;) {
		switch (c = *p++) {
		case '\0':
			if (*q != '\0')
				goto backtrack;
			return 1;
		case CTLESC:
			if (*q++ != *p++)
				goto backtrack;
			break;
		case '?':
			if (*q == '\0')
				return 0;
			if (localeisutf8) {
				wc = get_wc(&q);
				/*
				 * A '?' does not match invalid UTF-8 but a
				 * '*' does, so backtrack.
				 */
				if (wc == 0)
					goto backtrack;
			} else
				q++;
			break;
		case '*':
			c = *p;
			while (c == '*')
				c = *++p;
			/*
			 * If the pattern ends here, we know the string
			 * matches without needing to look at the rest of it.
			 */
			if (c == '\0')
				return 1;
			/*
			 * First try the shortest match for the '*' that
			 * could work. We can forget any earlier '*' since
			 * there is no way having it match more characters
			 * can help us, given that we are already here.
			 */
			bt_p = p;
			bt_q = q;
			break;
		case '[': {
			const char *savep, *saveq;
			int invert, found;
			wchar_t chr;

			savep = p, saveq = q;
			invert = 0;
			if (*p == '!' || *p == '^') {
				invert++;
				p++;
			}
			found = 0;
			if (*q == '\0')
				return 0;
			if (localeisutf8) {
				chr = get_wc(&q);
				if (chr == 0)
					goto backtrack;
			} else
				chr = (unsigned char)*q++;
			c = *p++;
			do {
				if (c == '\0') {
					p = savep, q = saveq;
					c = '[';
					goto dft;
				}
				if (c == '[' && *p == ':') {
					found |= match_charclass(p, chr, &end);
					if (end != NULL)
						p = end;
				}
				if (c == CTLESC)
					c = *p++;
				if (localeisutf8 && c & 0x80) {
					p--;
					wc = get_wc(&p);
					if (wc == 0) /* bad utf-8 */
						return 0;
				} else
					wc = (unsigned char)c;
				if (*p == '-' && p[1] != ']') {
					p++;
					if (*p == CTLESC)
						p++;
					if (localeisutf8) {
						wc2 = get_wc(&p);
						if (wc2 == 0) /* bad utf-8 */
							return 0;
					} else
						wc2 = (unsigned char)*p++;
					if (   collate_range_cmp(chr, wc) >= 0
					    && collate_range_cmp(chr, wc2) <= 0
					   )
						found = 1;
				} else {
					if (chr == wc)
						found = 1;
				}
			} while ((c = *p++) != ']');
			if (found == invert)
				goto backtrack;
			break;
		}
dft:	        default:
			if (*q == '\0')
				return 0;
			if (*q++ == c)
				break;
backtrack:
			/*
			 * If we have a mismatch (other than hitting the end
			 * of the string), go back to the last '*' seen and
			 * have it match one additional character.
			 */
			if (bt_p == NULL)
				return 0;
			if (*bt_q == '\0')
				return 0;
			bt_q++;
			p = bt_p;
			q = bt_q;
			break;
		}
	}
}



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

void
rmescapes(char *str)
{
	char *p, *q;

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



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

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

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

/*
 * Our own itoa().
 */

static void
cvtnum(int num, char *buf)
{
	char temp[32];
	int neg = num < 0;
	char *p = temp + 31;

	temp[31] = '\0';

	do {
		*--p = num % 10 + '0';
	} while ((num /= 10) != 0);

	if (neg)
		*--p = '-';

	memcpy(buf, p, temp + 32 - p);
}

/*
 * Do most of the work for wordexp(3).
 */

int
wordexpcmd(int argc, char **argv)
{
	size_t len;
	int i;

	out1fmt("%08x", argc - 1);
	for (i = 1, len = 0; i < argc; i++)
		len += strlen(argv[i]);
	out1fmt("%08x", (int)len);
	for (i = 1; i < argc; i++)
		outbin(argv[i], strlen(argv[i]) + 1, out1);
        return (0);
}

/*
 * Do most of the work for wordexp(3), new version.
 */

int
freebsd_wordexpcmd(int argc __unused, char **argv __unused)
{
	struct arglist arglist;
	union node *args, *n;
	size_t len;
	int ch;
	int protected = 0;
	int fd = -1;
	int i;

	while ((ch = nextopt("f:p")) != '\0') {
		switch (ch) {
		case 'f':
			fd = number(shoptarg);
			break;
		case 'p':
			protected = 1;
			break;
		}
	}
	if (*argptr != NULL)
		error("wrong number of arguments");
	if (fd < 0)
		error("missing fd");
	INTOFF;
	setinputfd(fd, 1);
	INTON;
	args = parsewordexp();
	popfile(); /* will also close fd */
	if (protected)
		for (n = args; n != NULL; n = n->narg.next) {
			if (n->narg.backquote != NULL) {
				outcslow('C', out1);
				error("command substitution disabled");
			}
		}
	outcslow(' ', out1);
	emptyarglist(&arglist);
	for (n = args; n != NULL; n = n->narg.next)
		expandarg(n, &arglist, EXP_FULL | EXP_TILDE);
	for (i = 0, len = 0; i < arglist.count; i++)
		len += strlen(arglist.args[i]);
	out1fmt("%016x %016zx", arglist.count, len);
	for (i = 0; i < arglist.count; i++)
		outbin(arglist.args[i], strlen(arglist.args[i]) + 1, out1);
	return (0);
}