xref: /freebsd/bin/sh/expand.c (revision 952d112864d8008aa87278a30a539d888a8493cd)
1 /*-
2  * Copyright (c) 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Kenneth Almquist.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. All advertising materials mentioning features or use of this software
17  *    must display the following acknowledgement:
18  *	This product includes software developed by the University of
19  *	California, Berkeley and its contributors.
20  * 4. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  *
36  *	$Id$
37  */
38 
39 #ifndef lint
40 static char const sccsid[] = "@(#)expand.c	8.5 (Berkeley) 5/15/95";
41 #endif /* not lint */
42 
43 #include <sys/types.h>
44 #include <sys/time.h>
45 #include <sys/stat.h>
46 #include <errno.h>
47 #include <dirent.h>
48 #include <unistd.h>
49 #include <pwd.h>
50 #include <stdlib.h>
51 #include <limits.h>
52 
53 /*
54  * Routines to expand arguments to commands.  We have to deal with
55  * backquotes, shell variables, and file metacharacters.
56  */
57 
58 #include "shell.h"
59 #include "main.h"
60 #include "nodes.h"
61 #include "eval.h"
62 #include "expand.h"
63 #include "syntax.h"
64 #include "parser.h"
65 #include "jobs.h"
66 #include "options.h"
67 #include "var.h"
68 #include "input.h"
69 #include "output.h"
70 #include "memalloc.h"
71 #include "error.h"
72 #include "mystring.h"
73 #include "arith.h"
74 #include "show.h"
75 
76 /*
77  * Structure specifying which parts of the string should be searched
78  * for IFS characters.
79  */
80 
81 struct ifsregion {
82 	struct ifsregion *next;	/* next region in list */
83 	int begoff;		/* offset of start of region */
84 	int endoff;		/* offset of end of region */
85 	int nulonly;		/* search for nul bytes only */
86 };
87 
88 
89 char *expdest;			/* output of current string */
90 struct nodelist *argbackq;	/* list of back quote expressions */
91 struct ifsregion ifsfirst;	/* first struct in list of ifs regions */
92 struct ifsregion *ifslastp;	/* last struct in list */
93 struct arglist exparg;		/* holds expanded arg list */
94 
95 STATIC void argstr __P((char *, int));
96 STATIC char *exptilde __P((char *, int));
97 STATIC void expbackq __P((union node *, int, int));
98 STATIC int subevalvar __P((char *, char *, int, int, int, int));
99 STATIC char *evalvar __P((char *, int));
100 STATIC int varisset __P((char *));
101 STATIC void varvalue __P((char *, int, int));
102 STATIC void recordregion __P((int, int, int));
103 STATIC void ifsbreakup __P((char *, struct arglist *));
104 STATIC void expandmeta __P((struct strlist *, int));
105 STATIC void expmeta __P((char *, char *));
106 STATIC void addfname __P((char *));
107 STATIC struct strlist *expsort __P((struct strlist *));
108 STATIC struct strlist *msort __P((struct strlist *, int));
109 STATIC int pmatch __P((char *, char *));
110 STATIC char *cvtnum __P((int, char *));
111 STATIC int collate_range_cmp __P((int, int));
112 
113 STATIC int collate_range_cmp (c1, c2)
114 	int c1, c2;
115 {
116 	static char s1[2], s2[2];
117 	int ret;
118 
119 	c1 &= UCHAR_MAX;
120 	c2 &= UCHAR_MAX;
121 	if (c1 == c2)
122 		return (0);
123 	s1[0] = c1;
124 	s2[0] = c2;
125 	if ((ret = strcoll(s1, s2)) != 0)
126 		return (ret);
127 	return (c1 - c2);
128 }
129 
130 /*
131  * Expand shell variables and backquotes inside a here document.
132  */
133 
134 void
135 expandhere(arg, fd)
136 	union node *arg;	/* the document */
137 	int fd;			/* where to write the expanded version */
138 	{
139 	herefd = fd;
140 	expandarg(arg, (struct arglist *)NULL, 0);
141 	xwrite(fd, stackblock(), expdest - stackblock());
142 }
143 
144 
145 /*
146  * Perform variable substitution and command substitution on an argument,
147  * placing the resulting list of arguments in arglist.  If EXP_FULL is true,
148  * perform splitting and file name expansion.  When arglist is NULL, perform
149  * here document expansion.
150  */
151 
152 void
153 expandarg(arg, arglist, flag)
154 	union node *arg;
155 	struct arglist *arglist;
156 	int flag;
157 {
158 	struct strlist *sp;
159 	char *p;
160 
161 	argbackq = arg->narg.backquote;
162 	STARTSTACKSTR(expdest);
163 	ifsfirst.next = NULL;
164 	ifslastp = NULL;
165 	argstr(arg->narg.text, flag);
166 	if (arglist == NULL) {
167 		return;			/* here document expanded */
168 	}
169 	STPUTC('\0', expdest);
170 	p = grabstackstr(expdest);
171 	exparg.lastp = &exparg.list;
172 	/*
173 	 * TODO - EXP_REDIR
174 	 */
175 	if (flag & EXP_FULL) {
176 		ifsbreakup(p, &exparg);
177 		*exparg.lastp = NULL;
178 		exparg.lastp = &exparg.list;
179 		expandmeta(exparg.list, flag);
180 	} else {
181 		if (flag & EXP_REDIR) /*XXX - for now, just remove escapes */
182 			rmescapes(p);
183 		sp = (struct strlist *)stalloc(sizeof (struct strlist));
184 		sp->text = p;
185 		*exparg.lastp = sp;
186 		exparg.lastp = &sp->next;
187 	}
188 	while (ifsfirst.next != NULL) {
189 		struct ifsregion *ifsp;
190 		INTOFF;
191 		ifsp = ifsfirst.next->next;
192 		ckfree(ifsfirst.next);
193 		ifsfirst.next = ifsp;
194 		INTON;
195 	}
196 	*exparg.lastp = NULL;
197 	if (exparg.list) {
198 		*arglist->lastp = exparg.list;
199 		arglist->lastp = exparg.lastp;
200 	}
201 }
202 
203 
204 
205 /*
206  * Perform variable and command substitution.  If EXP_FULL is set, output CTLESC
207  * characters to allow for further processing.  Otherwise treat
208  * $@ like $* since no splitting will be performed.
209  */
210 
211 STATIC void
212 argstr(p, flag)
213 	register char *p;
214 	int flag;
215 {
216 	register char c;
217 	int quotes = flag & (EXP_FULL | EXP_CASE);	/* do CTLESC */
218 	int firsteq = 1;
219 
220 	if (*p == '~' && (flag & (EXP_TILDE | EXP_VARTILDE)))
221 		p = exptilde(p, flag);
222 	for (;;) {
223 		switch (c = *p++) {
224 		case '\0':
225 		case CTLENDVAR: /* ??? */
226 			goto breakloop;
227 		case CTLESC:
228 			if (quotes)
229 				STPUTC(c, expdest);
230 			c = *p++;
231 			STPUTC(c, expdest);
232 			break;
233 		case CTLVAR:
234 			p = evalvar(p, flag);
235 			break;
236 		case CTLBACKQ:
237 		case CTLBACKQ|CTLQUOTE:
238 			expbackq(argbackq->n, c & CTLQUOTE, flag);
239 			argbackq = argbackq->next;
240 			break;
241 		case CTLENDARI:
242 			expari(flag);
243 			break;
244 		case ':':
245 		case '=':
246 			/*
247 			 * sort of a hack - expand tildes in variable
248 			 * assignments (after the first '=' and after ':'s).
249 			 */
250 			STPUTC(c, expdest);
251 			if (flag & EXP_VARTILDE && *p == '~') {
252 				if (c == '=') {
253 					if (firsteq)
254 						firsteq = 0;
255 					else
256 						break;
257 				}
258 				p = exptilde(p, flag);
259 			}
260 			break;
261 		default:
262 			STPUTC(c, expdest);
263 		}
264 	}
265 breakloop:;
266 }
267 
268 STATIC char *
269 exptilde(p, flag)
270 	char *p;
271 	int flag;
272 {
273 	char c, *startp = p;
274 	struct passwd *pw;
275 	char *home;
276 	int quotes = flag & (EXP_FULL | EXP_CASE);
277 
278 	while ((c = *p) != '\0') {
279 		switch(c) {
280 		case CTLESC:
281 			return (startp);
282 		case ':':
283 			if (flag & EXP_VARTILDE)
284 				goto done;
285 			break;
286 		case '/':
287 			goto done;
288 		}
289 		p++;
290 	}
291 done:
292 	*p = '\0';
293 	if (*(startp+1) == '\0') {
294 		if ((home = lookupvar("HOME")) == NULL)
295 			goto lose;
296 	} else {
297 		if ((pw = getpwnam(startp+1)) == NULL)
298 			goto lose;
299 		home = pw->pw_dir;
300 	}
301 	if (*home == '\0')
302 		goto lose;
303 	*p = c;
304 	while ((c = *home++) != '\0') {
305 		if (quotes && SQSYNTAX[c] == CCTL)
306 			STPUTC(CTLESC, expdest);
307 		STPUTC(c, expdest);
308 	}
309 	return (p);
310 lose:
311 	*p = c;
312 	return (startp);
313 }
314 
315 
316 /*
317  * Expand arithmetic expression.  Backup to start of expression,
318  * evaluate, place result in (backed up) result, adjust string position.
319  */
320 void
321 expari(flag)
322 	int flag;
323 {
324 	char *p, *start;
325 	int result;
326 	int quotes = flag & (EXP_FULL | EXP_CASE);
327 
328 	/*
329 	 * This routine is slightly over-compilcated for
330 	 * efficiency.  First we make sure there is
331 	 * enough space for the result, which may be bigger
332 	 * than the expression if we add exponentation.  Next we
333 	 * scan backwards looking for the start of arithmetic.  If the
334 	 * next previous character is a CTLESC character, then we
335 	 * have to rescan starting from the beginning since CTLESC
336 	 * characters have to be processed left to right.
337 	 */
338 #if INT_MAX / 1000000000 >= 10 || INT_MIN / 1000000000 <= -10
339 #error "integers with more than 10 digits are not supported"
340 #endif
341 	CHECKSTRSPACE(12 - 2, expdest);
342 	USTPUTC('\0', expdest);
343 	start = stackblock();
344 	p = expdest;
345 	while (*p != CTLARI && p >= start)
346 		--p;
347 	if (*p != CTLARI)
348 		error("missing CTLARI (shouldn't happen)");
349 	if (p > start && *(p-1) == CTLESC)
350 		for (p = start; *p != CTLARI; p++)
351 			if (*p == CTLESC)
352 				p++;
353 	if (quotes)
354 		rmescapes(p+1);
355 	result = arith(p+1);
356 	fmtstr(p, 12, "%d", result);
357 	while (*p++)
358 		;
359 	result = expdest - p + 1;
360 	STADJUST(-result, expdest);
361 }
362 
363 
364 /*
365  * Expand stuff in backwards quotes.
366  */
367 
368 STATIC void
369 expbackq(cmd, quoted, flag)
370 	union node *cmd;
371 	int quoted;
372 	int flag;
373 {
374 	struct backcmd in;
375 	int i;
376 	char buf[128];
377 	char *p;
378 	char *dest = expdest;
379 	struct ifsregion saveifs, *savelastp;
380 	struct nodelist *saveargbackq;
381 	char lastc;
382 	int startloc = dest - stackblock();
383 	char const *syntax = quoted? DQSYNTAX : BASESYNTAX;
384 	int saveherefd;
385 	int quotes = flag & (EXP_FULL | EXP_CASE);
386 
387 	INTOFF;
388 	saveifs = ifsfirst;
389 	savelastp = ifslastp;
390 	saveargbackq = argbackq;
391 	saveherefd = herefd;
392 	herefd = -1;
393 	p = grabstackstr(dest);
394 	evalbackcmd(cmd, &in);
395 	ungrabstackstr(p, dest);
396 	ifsfirst = saveifs;
397 	ifslastp = savelastp;
398 	argbackq = saveargbackq;
399 	herefd = saveherefd;
400 
401 	p = in.buf;
402 	lastc = '\0';
403 	for (;;) {
404 		if (--in.nleft < 0) {
405 			if (in.fd < 0)
406 				break;
407 			while ((i = read(in.fd, buf, sizeof buf)) < 0 && errno == EINTR);
408 			TRACE(("expbackq: read returns %d\n", i));
409 			if (i <= 0)
410 				break;
411 			p = buf;
412 			in.nleft = i - 1;
413 		}
414 		lastc = *p++;
415 		if (lastc != '\0') {
416 			if (quotes && syntax[lastc] == CCTL)
417 				STPUTC(CTLESC, dest);
418 			STPUTC(lastc, dest);
419 		}
420 	}
421 
422 	/* Eat all trailing newlines */
423 	for (p--; lastc == '\n'; lastc = *--p)
424 		STUNPUTC(dest);
425 
426 	if (in.fd >= 0)
427 		close(in.fd);
428 	if (in.buf)
429 		ckfree(in.buf);
430 	if (in.jp)
431 		exitstatus = waitforjob(in.jp);
432 	if (quoted == 0)
433 		recordregion(startloc, dest - stackblock(), 0);
434 	TRACE(("evalbackq: size=%d: \"%.*s\"\n",
435 		(dest - stackblock()) - startloc,
436 		(dest - stackblock()) - startloc,
437 		stackblock() + startloc));
438 	expdest = dest;
439 	INTON;
440 }
441 
442 
443 
444 STATIC int
445 subevalvar(p, str, strloc, subtype, startloc, varflags)
446 	char *p;
447 	char *str;
448 	int strloc;
449 	int subtype;
450 	int startloc;
451 	int varflags;
452 {
453 	char *startp;
454 	char *loc = NULL;
455 	int c = 0;
456 	int saveherefd = herefd;
457 	struct nodelist *saveargbackq = argbackq;
458 	int amount;
459 
460 	herefd = -1;
461 	argstr(p, 0);
462 	STACKSTRNUL(expdest);
463 	herefd = saveherefd;
464 	argbackq = saveargbackq;
465 	startp = stackblock() + startloc;
466 	if (str == NULL)
467 	    str = stackblock() + strloc;
468 
469 	switch (subtype) {
470 	case VSASSIGN:
471 		setvar(str, startp, 0);
472 		amount = startp - expdest;
473 		STADJUST(amount, expdest);
474 		varflags &= ~VSNUL;
475 		if (c != 0)
476 			*loc = c;
477 		return 1;
478 
479 	case VSQUESTION:
480 		if (*p != CTLENDVAR) {
481 			outfmt(&errout, "%s\n", startp);
482 			error((char *)NULL);
483 		}
484 		error("%.*s: parameter %snot set", p - str - 1,
485 		      str, (varflags & VSNUL) ? "null or "
486 					      : nullstr);
487 		return 0;
488 
489 	case VSTRIMLEFT:
490 		for (loc = startp; loc < str - 1; loc++) {
491 			c = *loc;
492 			*loc = '\0';
493 			if (patmatch(str, startp)) {
494 				*loc = c;
495 				goto recordleft;
496 			}
497 			*loc = c;
498 		}
499 		return 0;
500 
501 	case VSTRIMLEFTMAX:
502 		for (loc = str - 1; loc >= startp; loc--) {
503 			c = *loc;
504 			*loc = '\0';
505 			if (patmatch(str, startp)) {
506 				*loc = c;
507 				goto recordleft;
508 			}
509 			*loc = c;
510 		}
511 		return 0;
512 
513 	case VSTRIMRIGHT:
514 		for (loc = str - 1; loc >= startp; loc--) {
515 			if (patmatch(str, loc)) {
516 				amount = loc - expdest;
517 				STADJUST(amount, expdest);
518 				return 1;
519 			}
520 		}
521 		return 0;
522 
523 	case VSTRIMRIGHTMAX:
524 		for (loc = startp; loc < str - 1; loc++) {
525 			if (patmatch(str, loc)) {
526 				amount = loc - expdest;
527 				STADJUST(amount, expdest);
528 				return 1;
529 			}
530 		}
531 		return 0;
532 
533 
534 	default:
535 		abort();
536 	}
537 
538 recordleft:
539 	amount = ((str - 1) - (loc - startp)) - expdest;
540 	STADJUST(amount, expdest);
541 	while (loc != str - 1)
542 		*startp++ = *loc++;
543 	return 1;
544 }
545 
546 
547 /*
548  * Expand a variable, and return a pointer to the next character in the
549  * input string.
550  */
551 
552 STATIC char *
553 evalvar(p, flag)
554 	char *p;
555 	int flag;
556 {
557 	int subtype;
558 	int varflags;
559 	char *var;
560 	char *val;
561 	char *pat;
562 	int c;
563 	int set;
564 	int special;
565 	int startloc;
566 	int varlen;
567 	int easy;
568 	int quotes = flag & (EXP_FULL | EXP_CASE);
569 
570 	varflags = *p++;
571 	subtype = varflags & VSTYPE;
572 	var = p;
573 	special = 0;
574 	if (! is_name(*p))
575 		special = 1;
576 	p = strchr(p, '=') + 1;
577 again: /* jump here after setting a variable with ${var=text} */
578 	if (special) {
579 		set = varisset(var);
580 		val = NULL;
581 	} else {
582 		val = lookupvar(var);
583 		if (val == NULL || ((varflags & VSNUL) && val[0] == '\0')) {
584 			val = NULL;
585 			set = 0;
586 		} else
587 			set = 1;
588 	}
589 	varlen = 0;
590 	startloc = expdest - stackblock();
591 	if (set && subtype != VSPLUS) {
592 		/* insert the value of the variable */
593 		if (special) {
594 			char *exp, *oexpdest = expdest;
595 			varvalue(var, varflags & VSQUOTE, flag & EXP_FULL);
596 			if (subtype == VSLENGTH) {
597 				for (exp = oexpdest;exp != expdest; exp++)
598 					varlen++;
599 				expdest = oexpdest;
600 			}
601 		} else {
602 			char const *syntax = (varflags & VSQUOTE) ? DQSYNTAX
603 								  : BASESYNTAX;
604 
605 			if (subtype == VSLENGTH) {
606 				for (;*val; val++)
607 					varlen++;
608 			}
609 			else {
610 				while (*val) {
611 					if (quotes && syntax[*val] == CCTL)
612 						STPUTC(CTLESC, expdest);
613 					STPUTC(*val++, expdest);
614 				}
615 
616 			}
617 		}
618 	}
619 
620 	if (subtype == VSPLUS)
621 		set = ! set;
622 
623 	easy = ((varflags & VSQUOTE) == 0 ||
624 		(*var == '@' && shellparam.nparam != 1));
625 
626 
627 	switch (subtype) {
628 	case VSLENGTH:
629 		expdest = cvtnum(varlen, expdest);
630 		goto record;
631 
632 	case VSNORMAL:
633 		if (!easy)
634 			break;
635 record:
636 		recordregion(startloc, expdest - stackblock(),
637 			     varflags & VSQUOTE);
638 		break;
639 
640 	case VSPLUS:
641 	case VSMINUS:
642 		if (!set) {
643 			argstr(p, flag);
644 			break;
645 		}
646 		if (easy)
647 			goto record;
648 		break;
649 
650 	case VSTRIMLEFT:
651 	case VSTRIMLEFTMAX:
652 	case VSTRIMRIGHT:
653 	case VSTRIMRIGHTMAX:
654 		if (!set)
655 			break;
656 		/*
657 		 * Terminate the string and start recording the pattern
658 		 * right after it
659 		 */
660 		STPUTC('\0', expdest);
661 		pat = expdest;
662 		if (subevalvar(p, NULL, expdest - stackblock(), subtype,
663 			       startloc, varflags))
664 			goto record;
665 		break;
666 
667 	case VSASSIGN:
668 	case VSQUESTION:
669 		if (!set) {
670 			if (subevalvar(p, var, 0, subtype, startloc, varflags)) {
671 				varflags &= ~VSNUL;
672 				goto again;
673 			}
674 			break;
675 		}
676 		if (easy)
677 			goto record;
678 		break;
679 
680 	default:
681 		abort();
682 	}
683 
684 	if (subtype != VSNORMAL) {	/* skip to end of alternative */
685 		int nesting = 1;
686 		for (;;) {
687 			if ((c = *p++) == CTLESC)
688 				p++;
689 			else if (c == CTLBACKQ || c == (CTLBACKQ|CTLQUOTE)) {
690 				if (set)
691 					argbackq = argbackq->next;
692 			} else if (c == CTLVAR) {
693 				if ((*p++ & VSTYPE) != VSNORMAL)
694 					nesting++;
695 			} else if (c == CTLENDVAR) {
696 				if (--nesting == 0)
697 					break;
698 			}
699 		}
700 	}
701 	return p;
702 }
703 
704 
705 
706 /*
707  * Test whether a specialized variable is set.
708  */
709 
710 STATIC int
711 varisset(name)
712 	char *name;
713 	{
714 	char **ap;
715 
716 	if (*name == '!') {
717 		if (backgndpid == -1)
718 			return 0;
719 	} else if (*name == '@' || *name == '*') {
720 		if (*shellparam.p == NULL)
721 			return 0;
722 	} else if (is_digit(*name)) {
723 		int num = atoi(name);
724 		ap = shellparam.p;
725 		while (--num >= 0)
726 			if (*ap++ == NULL)
727 				return 0;
728 	}
729 	return 1;
730 }
731 
732 
733 
734 /*
735  * Add the value of a specialized variable to the stack string.
736  */
737 
738 STATIC void
739 varvalue(name, quoted, allow_split)
740 	char *name;
741 	int quoted;
742 	int allow_split;
743 {
744 	int num;
745 	char *p;
746 	int i;
747 	extern int oexitstatus;
748 	char sep;
749 	char **ap;
750 	char const *syntax;
751 
752 #define STRTODEST(p) \
753 	do {\
754 	if (allow_split) { \
755 		syntax = quoted? DQSYNTAX : BASESYNTAX; \
756 		while (*p) { \
757 			if (syntax[*p] == CCTL) \
758 				STPUTC(CTLESC, expdest); \
759 			STPUTC(*p++, expdest); \
760 		} \
761 	} else \
762 		while (*p) \
763 			STPUTC(*p++, expdest); \
764 	} while (0)
765 
766 
767 	switch (*name) {
768 	case '$':
769 		num = rootpid;
770 		goto numvar;
771 	case '?':
772 		num = oexitstatus;
773 		goto numvar;
774 	case '#':
775 		num = shellparam.nparam;
776 		goto numvar;
777 	case '!':
778 		num = backgndpid;
779 numvar:
780 		expdest = cvtnum(num, expdest);
781 		break;
782 	case '-':
783 		for (i = 0 ; i < NOPTS ; i++) {
784 			if (optlist[i].val)
785 				STPUTC(optlist[i].letter, expdest);
786 		}
787 		break;
788 	case '@':
789 		if (allow_split) {
790 			sep = '\0';
791 			goto allargs;
792 		}
793 		/* fall through */
794 	case '*':
795 		sep = ' ';
796 allargs:
797 		for (ap = shellparam.p ; (p = *ap++) != NULL ; ) {
798 			STRTODEST(p);
799 			if (*ap)
800 				STPUTC(sep, expdest);
801 		}
802 		break;
803 	case '0':
804 		p = arg0;
805 		STRTODEST(p);
806 		break;
807 	default:
808 		if (is_digit(*name)) {
809 			num = atoi(name);
810 			if (num > 0 && num <= shellparam.nparam) {
811 				p = shellparam.p[num - 1];
812 				STRTODEST(p);
813 			}
814 		}
815 		break;
816 	}
817 }
818 
819 
820 
821 /*
822  * Record the the fact that we have to scan this region of the
823  * string for IFS characters.
824  */
825 
826 STATIC void
827 recordregion(start, end, nulonly)
828 	int start;
829 	int end;
830 	int nulonly;
831 {
832 	register struct ifsregion *ifsp;
833 
834 	if (ifslastp == NULL) {
835 		ifsp = &ifsfirst;
836 	} else {
837 		ifsp = (struct ifsregion *)ckmalloc(sizeof (struct ifsregion));
838 		ifslastp->next = ifsp;
839 	}
840 	ifslastp = ifsp;
841 	ifslastp->next = NULL;
842 	ifslastp->begoff = start;
843 	ifslastp->endoff = end;
844 	ifslastp->nulonly = nulonly;
845 }
846 
847 
848 
849 /*
850  * Break the argument string into pieces based upon IFS and add the
851  * strings to the argument list.  The regions of the string to be
852  * searched for IFS characters have been stored by recordregion.
853  */
854 STATIC void
855 ifsbreakup(string, arglist)
856 	char *string;
857 	struct arglist *arglist;
858 	{
859 	struct ifsregion *ifsp;
860 	struct strlist *sp;
861 	char *start;
862 	register char *p;
863 	char *q;
864 	char *ifs;
865 	int ifsspc;
866 
867 
868 	start = string;
869 	if (ifslastp != NULL) {
870 		ifsp = &ifsfirst;
871 		do {
872 			p = string + ifsp->begoff;
873 			ifs = ifsp->nulonly? nullstr : ifsval();
874 			ifsspc = strchr(ifs, ' ') != NULL;
875 			while (p < string + ifsp->endoff) {
876 				q = p;
877 				if (*p == CTLESC)
878 					p++;
879 				if (strchr(ifs, *p++)) {
880 					if (q > start || !ifsspc) {
881 						*q = '\0';
882 						sp = (struct strlist *)stalloc(sizeof *sp);
883 						sp->text = start;
884 						*arglist->lastp = sp;
885 						arglist->lastp = &sp->next;
886 					}
887 					if (ifsspc) {
888 						for (;;) {
889 							if (p >= string + ifsp->endoff)
890 								break;
891 							q = p;
892 							if (*p == CTLESC)
893 								p++;
894 							if (strchr(ifs, *p++) == NULL) {
895 								p = q;
896 								break;
897 							}
898 						}
899 					}
900 					start = p;
901 				}
902 			}
903 		} while ((ifsp = ifsp->next) != NULL);
904 		if (*start || (!ifsspc && start > string)) {
905 			sp = (struct strlist *)stalloc(sizeof *sp);
906 			sp->text = start;
907 			*arglist->lastp = sp;
908 			arglist->lastp = &sp->next;
909 		}
910 	} else {
911 		sp = (struct strlist *)stalloc(sizeof *sp);
912 		sp->text = start;
913 		*arglist->lastp = sp;
914 		arglist->lastp = &sp->next;
915 	}
916 }
917 
918 
919 
920 /*
921  * Expand shell metacharacters.  At this point, the only control characters
922  * should be escapes.  The results are stored in the list exparg.
923  */
924 
925 char *expdir;
926 
927 
928 STATIC void
929 expandmeta(str, flag)
930 	struct strlist *str;
931 	int flag;
932 {
933 	char *p;
934 	struct strlist **savelastp;
935 	struct strlist *sp;
936 	char c;
937 	/* TODO - EXP_REDIR */
938 
939 	while (str) {
940 		if (fflag)
941 			goto nometa;
942 		p = str->text;
943 		for (;;) {			/* fast check for meta chars */
944 			if ((c = *p++) == '\0')
945 				goto nometa;
946 			if (c == '*' || c == '?' || c == '[' || c == '!')
947 				break;
948 		}
949 		savelastp = exparg.lastp;
950 		INTOFF;
951 		if (expdir == NULL) {
952 			int i = strlen(str->text);
953 			expdir = ckmalloc(i < 2048 ? 2048 : i); /* XXX */
954 		}
955 
956 		expmeta(expdir, str->text);
957 		ckfree(expdir);
958 		expdir = NULL;
959 		INTON;
960 		if (exparg.lastp == savelastp) {
961 			/*
962 			 * no matches
963 			 */
964 nometa:
965 			*exparg.lastp = str;
966 			rmescapes(str->text);
967 			exparg.lastp = &str->next;
968 		} else {
969 			*exparg.lastp = NULL;
970 			*savelastp = sp = expsort(*savelastp);
971 			while (sp->next != NULL)
972 				sp = sp->next;
973 			exparg.lastp = &sp->next;
974 		}
975 		str = str->next;
976 	}
977 }
978 
979 
980 /*
981  * Do metacharacter (i.e. *, ?, [...]) expansion.
982  */
983 
984 STATIC void
985 expmeta(enddir, name)
986 	char *enddir;
987 	char *name;
988 	{
989 	register char *p;
990 	char *q;
991 	char *start;
992 	char *endname;
993 	int metaflag;
994 	struct stat statb;
995 	DIR *dirp;
996 	struct dirent *dp;
997 	int atend;
998 	int matchdot;
999 
1000 	metaflag = 0;
1001 	start = name;
1002 	for (p = name ; ; p++) {
1003 		if (*p == '*' || *p == '?')
1004 			metaflag = 1;
1005 		else if (*p == '[') {
1006 			q = p + 1;
1007 			if (*q == '!')
1008 				q++;
1009 			for (;;) {
1010 				if (*q == CTLESC)
1011 					q++;
1012 				if (*q == '/' || *q == '\0')
1013 					break;
1014 				if (*++q == ']') {
1015 					metaflag = 1;
1016 					break;
1017 				}
1018 			}
1019 		} else if (*p == '!' && p[1] == '!'	&& (p == name || p[-1] == '/')) {
1020 			metaflag = 1;
1021 		} else if (*p == '\0')
1022 			break;
1023 		else if (*p == CTLESC)
1024 			p++;
1025 		if (*p == '/') {
1026 			if (metaflag)
1027 				break;
1028 			start = p + 1;
1029 		}
1030 	}
1031 	if (metaflag == 0) {	/* we've reached the end of the file name */
1032 		if (enddir != expdir)
1033 			metaflag++;
1034 		for (p = name ; ; p++) {
1035 			if (*p == CTLESC)
1036 				p++;
1037 			*enddir++ = *p;
1038 			if (*p == '\0')
1039 				break;
1040 		}
1041 		if (metaflag == 0 || stat(expdir, &statb) >= 0)
1042 			addfname(expdir);
1043 		return;
1044 	}
1045 	endname = p;
1046 	if (start != name) {
1047 		p = name;
1048 		while (p < start) {
1049 			if (*p == CTLESC)
1050 				p++;
1051 			*enddir++ = *p++;
1052 		}
1053 	}
1054 	if (enddir == expdir) {
1055 		p = ".";
1056 	} else if (enddir == expdir + 1 && *expdir == '/') {
1057 		p = "/";
1058 	} else {
1059 		p = expdir;
1060 		enddir[-1] = '\0';
1061 	}
1062 	if ((dirp = opendir(p)) == NULL)
1063 		return;
1064 	if (enddir != expdir)
1065 		enddir[-1] = '/';
1066 	if (*endname == 0) {
1067 		atend = 1;
1068 	} else {
1069 		atend = 0;
1070 		*endname++ = '\0';
1071 	}
1072 	matchdot = 0;
1073 	if (start[0] == '.' || (start[0] == CTLESC && start[1] == '.'))
1074 		matchdot++;
1075 	while (! int_pending() && (dp = readdir(dirp)) != NULL) {
1076 		if (dp->d_name[0] == '.' && ! matchdot)
1077 			continue;
1078 		if (patmatch(start, dp->d_name)) {
1079 			if (atend) {
1080 				scopy(dp->d_name, enddir);
1081 				addfname(expdir);
1082 			} else {
1083 				char *q;
1084 				for (p = enddir, q = dp->d_name;
1085 				     (*p++ = *q++) != '\0';)
1086 					continue;
1087 				p[-1] = '/';
1088 				expmeta(p, endname);
1089 			}
1090 		}
1091 	}
1092 	closedir(dirp);
1093 	if (! atend)
1094 		endname[-1] = '/';
1095 }
1096 
1097 
1098 /*
1099  * Add a file name to the list.
1100  */
1101 
1102 STATIC void
1103 addfname(name)
1104 	char *name;
1105 	{
1106 	char *p;
1107 	struct strlist *sp;
1108 
1109 	p = stalloc(strlen(name) + 1);
1110 	scopy(name, p);
1111 	sp = (struct strlist *)stalloc(sizeof *sp);
1112 	sp->text = p;
1113 	*exparg.lastp = sp;
1114 	exparg.lastp = &sp->next;
1115 }
1116 
1117 
1118 /*
1119  * Sort the results of file name expansion.  It calculates the number of
1120  * strings to sort and then calls msort (short for merge sort) to do the
1121  * work.
1122  */
1123 
1124 STATIC struct strlist *
1125 expsort(str)
1126 	struct strlist *str;
1127 	{
1128 	int len;
1129 	struct strlist *sp;
1130 
1131 	len = 0;
1132 	for (sp = str ; sp ; sp = sp->next)
1133 		len++;
1134 	return msort(str, len);
1135 }
1136 
1137 
1138 STATIC struct strlist *
1139 msort(list, len)
1140 	struct strlist *list;
1141 	int len;
1142 {
1143 	struct strlist *p, *q = NULL;
1144 	struct strlist **lpp;
1145 	int half;
1146 	int n;
1147 
1148 	if (len <= 1)
1149 		return list;
1150 	half = len >> 1;
1151 	p = list;
1152 	for (n = half ; --n >= 0 ; ) {
1153 		q = p;
1154 		p = p->next;
1155 	}
1156 	q->next = NULL;			/* terminate first half of list */
1157 	q = msort(list, half);		/* sort first half of list */
1158 	p = msort(p, len - half);		/* sort second half */
1159 	lpp = &list;
1160 	for (;;) {
1161 		if (strcmp(p->text, q->text) < 0) {
1162 			*lpp = p;
1163 			lpp = &p->next;
1164 			if ((p = *lpp) == NULL) {
1165 				*lpp = q;
1166 				break;
1167 			}
1168 		} else {
1169 			*lpp = q;
1170 			lpp = &q->next;
1171 			if ((q = *lpp) == NULL) {
1172 				*lpp = p;
1173 				break;
1174 			}
1175 		}
1176 	}
1177 	return list;
1178 }
1179 
1180 
1181 
1182 /*
1183  * Returns true if the pattern matches the string.
1184  */
1185 
1186 int
1187 patmatch(pattern, string)
1188 	char *pattern;
1189 	char *string;
1190 	{
1191 #ifdef notdef
1192 	if (pattern[0] == '!' && pattern[1] == '!')
1193 		return 1 - pmatch(pattern + 2, string);
1194 	else
1195 #endif
1196 		return pmatch(pattern, string);
1197 }
1198 
1199 
1200 STATIC int
1201 pmatch(pattern, string)
1202 	char *pattern;
1203 	char *string;
1204 	{
1205 	register char *p, *q;
1206 	register char c;
1207 
1208 	p = pattern;
1209 	q = string;
1210 	for (;;) {
1211 		switch (c = *p++) {
1212 		case '\0':
1213 			goto breakloop;
1214 		case CTLESC:
1215 			if (*q++ != *p++)
1216 				return 0;
1217 			break;
1218 		case '?':
1219 			if (*q++ == '\0')
1220 				return 0;
1221 			break;
1222 		case '*':
1223 			c = *p;
1224 			if (c != CTLESC && c != '?' && c != '*' && c != '[') {
1225 				while (*q != c) {
1226 					if (*q == '\0')
1227 						return 0;
1228 					q++;
1229 				}
1230 			}
1231 			do {
1232 				if (pmatch(p, q))
1233 					return 1;
1234 			} while (*q++ != '\0');
1235 			return 0;
1236 		case '[': {
1237 			char *endp;
1238 			int invert, found;
1239 			char chr;
1240 
1241 			endp = p;
1242 			if (*endp == '!')
1243 				endp++;
1244 			for (;;) {
1245 				if (*endp == '\0')
1246 					goto dft;		/* no matching ] */
1247 				if (*endp == CTLESC)
1248 					endp++;
1249 				if (*++endp == ']')
1250 					break;
1251 			}
1252 			invert = 0;
1253 			if (*p == '!') {
1254 				invert++;
1255 				p++;
1256 			}
1257 			found = 0;
1258 			chr = *q++;
1259 			if (chr == '\0')
1260 				return 0;
1261 			c = *p++;
1262 			do {
1263 				if (c == CTLESC)
1264 					c = *p++;
1265 				if (*p == '-' && p[1] != ']') {
1266 					p++;
1267 					if (*p == CTLESC)
1268 						p++;
1269 					if (   collate_range_cmp(chr, c) >= 0
1270 					    && collate_range_cmp(chr, *p) <= 0
1271 					   )
1272 						found = 1;
1273 					p++;
1274 				} else {
1275 					if (chr == c)
1276 						found = 1;
1277 				}
1278 			} while ((c = *p++) != ']');
1279 			if (found == invert)
1280 				return 0;
1281 			break;
1282 		}
1283 dft:	        default:
1284 			if (*q++ != c)
1285 				return 0;
1286 			break;
1287 		}
1288 	}
1289 breakloop:
1290 	if (*q != '\0')
1291 		return 0;
1292 	return 1;
1293 }
1294 
1295 
1296 
1297 /*
1298  * Remove any CTLESC characters from a string.
1299  */
1300 
1301 void
1302 rmescapes(str)
1303 	char *str;
1304 	{
1305 	register char *p, *q;
1306 
1307 	p = str;
1308 	while (*p != CTLESC) {
1309 		if (*p++ == '\0')
1310 			return;
1311 	}
1312 	q = p;
1313 	while (*p) {
1314 		if (*p == CTLESC)
1315 			p++;
1316 		*q++ = *p++;
1317 	}
1318 	*q = '\0';
1319 }
1320 
1321 
1322 
1323 /*
1324  * See if a pattern matches in a case statement.
1325  */
1326 
1327 int
1328 casematch(pattern, val)
1329 	union node *pattern;
1330 	char *val;
1331 	{
1332 	struct stackmark smark;
1333 	int result;
1334 	char *p;
1335 
1336 	setstackmark(&smark);
1337 	argbackq = pattern->narg.backquote;
1338 	STARTSTACKSTR(expdest);
1339 	ifslastp = NULL;
1340 	argstr(pattern->narg.text, EXP_TILDE | EXP_CASE);
1341 	STPUTC('\0', expdest);
1342 	p = grabstackstr(expdest);
1343 	result = patmatch(p, val);
1344 	popstackmark(&smark);
1345 	return result;
1346 }
1347 
1348 /*
1349  * Our own itoa().
1350  */
1351 
1352 STATIC char *
1353 cvtnum(num, buf)
1354 	int num;
1355 	char *buf;
1356 	{
1357 	char temp[32];
1358 	int neg = num < 0;
1359 	char *p = temp + 31;
1360 
1361 	temp[31] = '\0';
1362 
1363 	do {
1364 		*--p = num % 10 + '0';
1365 	} while ((num /= 10) != 0);
1366 
1367 	if (neg)
1368 		*--p = '-';
1369 
1370 	while (*p)
1371 		STPUTC(*p++, buf);
1372 	return buf;
1373 }
1374