var.c revision 262951 
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 * 4. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#ifndef lint
34#if 0
35static char sccsid[] = "@(#)var.c	8.3 (Berkeley) 5/4/95";
36#endif
37#endif /* not lint */
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD: stable/10/bin/sh/var.c 262951 2014-03-09 17:04:31Z jmmv $");
40
41#include <unistd.h>
42#include <stdlib.h>
43#include <paths.h>
44
45/*
46 * Shell variables.
47 */
48
49#include <locale.h>
50#include <langinfo.h>
51
52#include "shell.h"
53#include "output.h"
54#include "expand.h"
55#include "nodes.h"	/* for other headers */
56#include "eval.h"	/* defines cmdenviron */
57#include "exec.h"
58#include "syntax.h"
59#include "options.h"
60#include "mail.h"
61#include "var.h"
62#include "memalloc.h"
63#include "error.h"
64#include "mystring.h"
65#include "parser.h"
66#include "builtins.h"
67#ifndef NO_HISTORY
68#include "myhistedit.h"
69#endif
70
71
72#define VTABSIZE 39
73
74
75struct varinit {
76	struct var *var;
77	int flags;
78	const char *text;
79	void (*func)(const char *);
80};
81
82
83#ifndef NO_HISTORY
84struct var vhistsize;
85struct var vterm;
86#endif
87struct var vifs;
88struct var vmail;
89struct var vmpath;
90struct var vpath;
91struct var vps1;
92struct var vps2;
93struct var vps4;
94static struct var voptind;
95struct var vdisvfork;
96
97int forcelocal;
98
99static const struct varinit varinit[] = {
100#ifndef NO_HISTORY
101	{ &vhistsize,	VUNSET,				"HISTSIZE=",
102	  sethistsize },
103#endif
104	{ &vifs,	0,				"IFS= \t\n",
105	  NULL },
106	{ &vmail,	VUNSET,				"MAIL=",
107	  NULL },
108	{ &vmpath,	VUNSET,				"MAILPATH=",
109	  NULL },
110	{ &vpath,	0,				"PATH=" _PATH_DEFPATH,
111	  changepath },
112	/*
113	 * vps1 depends on uid
114	 */
115	{ &vps2,	0,				"PS2=> ",
116	  NULL },
117	{ &vps4,	0,				"PS4=+ ",
118	  NULL },
119#ifndef NO_HISTORY
120	{ &vterm,	VUNSET,				"TERM=",
121	  setterm },
122#endif
123	{ &voptind,	0,				"OPTIND=1",
124	  getoptsreset },
125	{ &vdisvfork,	VUNSET,				"SH_DISABLE_VFORK=",
126	  NULL },
127	{ NULL,	0,				NULL,
128	  NULL }
129};
130
131static struct var *vartab[VTABSIZE];
132
133static const char *const locale_names[7] = {
134	"LC_COLLATE", "LC_CTYPE", "LC_MONETARY",
135	"LC_NUMERIC", "LC_TIME", "LC_MESSAGES", NULL
136};
137static const int locale_categories[7] = {
138	LC_COLLATE, LC_CTYPE, LC_MONETARY, LC_NUMERIC, LC_TIME, LC_MESSAGES, 0
139};
140
141static int varequal(const char *, const char *);
142static struct var *find_var(const char *, struct var ***, int *);
143static int localevar(const char *);
144
145extern char **environ;
146
147/*
148 * This routine initializes the builtin variables and imports the environment.
149 * It is called when the shell is initialized.
150 */
151
152void
153initvar(void)
154{
155	char ppid[20];
156	const struct varinit *ip;
157	struct var *vp;
158	struct var **vpp;
159	char **envp;
160
161	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
162		if (find_var(ip->text, &vpp, &vp->name_len) != NULL)
163			continue;
164		vp->next = *vpp;
165		*vpp = vp;
166		vp->text = __DECONST(char *, ip->text);
167		vp->flags = ip->flags | VSTRFIXED | VTEXTFIXED;
168		vp->func = ip->func;
169	}
170	/*
171	 * PS1 depends on uid
172	 */
173	if (find_var("PS1", &vpp, &vps1.name_len) == NULL) {
174		vps1.next = *vpp;
175		*vpp = &vps1;
176		vps1.text = __DECONST(char *, geteuid() ? "PS1=$ " : "PS1=# ");
177		vps1.flags = VSTRFIXED|VTEXTFIXED;
178	}
179	fmtstr(ppid, sizeof(ppid), "%d", (int)getppid());
180	setvarsafe("PPID", ppid, 0);
181	for (envp = environ ; *envp ; envp++) {
182		if (strchr(*envp, '=')) {
183			setvareq(*envp, VEXPORT|VTEXTFIXED);
184		}
185	}
186	setvareq("OPTIND=1", VTEXTFIXED);
187}
188
189/*
190 * Safe version of setvar, returns 1 on success 0 on failure.
191 */
192
193int
194setvarsafe(const char *name, const char *val, int flags)
195{
196	struct jmploc jmploc;
197	struct jmploc *const savehandler = handler;
198	int err = 0;
199	int inton;
200
201	inton = is_int_on();
202	if (setjmp(jmploc.loc))
203		err = 1;
204	else {
205		handler = &jmploc;
206		setvar(name, val, flags);
207	}
208	handler = savehandler;
209	SETINTON(inton);
210	return err;
211}
212
213/*
214 * Set the value of a variable.  The flags argument is stored with the
215 * flags of the variable.  If val is NULL, the variable is unset.
216 */
217
218void
219setvar(const char *name, const char *val, int flags)
220{
221	const char *p;
222	size_t len;
223	size_t namelen;
224	size_t vallen;
225	char *nameeq;
226	int isbad;
227
228	isbad = 0;
229	p = name;
230	if (! is_name(*p))
231		isbad = 1;
232	p++;
233	for (;;) {
234		if (! is_in_name(*p)) {
235			if (*p == '\0' || *p == '=')
236				break;
237			isbad = 1;
238		}
239		p++;
240	}
241	namelen = p - name;
242	if (isbad)
243		error("%.*s: bad variable name", (int)namelen, name);
244	len = namelen + 2;		/* 2 is space for '=' and '\0' */
245	if (val == NULL) {
246		flags |= VUNSET;
247		vallen = 0;
248	} else {
249		vallen = strlen(val);
250		len += vallen;
251	}
252	nameeq = ckmalloc(len);
253	memcpy(nameeq, name, namelen);
254	nameeq[namelen] = '=';
255	if (val)
256		memcpy(nameeq + namelen + 1, val, vallen + 1);
257	else
258		nameeq[namelen + 1] = '\0';
259	setvareq(nameeq, flags);
260}
261
262static int
263localevar(const char *s)
264{
265	const char *const *ss;
266
267	if (*s != 'L')
268		return 0;
269	if (varequal(s + 1, "ANG"))
270		return 1;
271	if (strncmp(s + 1, "C_", 2) != 0)
272		return 0;
273	if (varequal(s + 3, "ALL"))
274		return 1;
275	for (ss = locale_names; *ss ; ss++)
276		if (varequal(s + 3, *ss + 3))
277			return 1;
278	return 0;
279}
280
281
282/*
283 * Sets/unsets an environment variable from a pointer that may actually be a
284 * pointer into environ where the string should not be manipulated.
285 */
286static void
287change_env(const char *s, int set)
288{
289	char *eqp;
290	char *ss;
291
292	ss = savestr(s);
293	if ((eqp = strchr(ss, '=')) != NULL)
294		*eqp = '\0';
295	if (set && eqp != NULL)
296		(void) setenv(ss, eqp + 1, 1);
297	else
298		(void) unsetenv(ss);
299	ckfree(ss);
300
301	return;
302}
303
304
305/*
306 * Same as setvar except that the variable and value are passed in
307 * the first argument as name=value.  Since the first argument will
308 * be actually stored in the table, it should not be a string that
309 * will go away.
310 */
311
312void
313setvareq(char *s, int flags)
314{
315	struct var *vp, **vpp;
316	int nlen;
317
318	if (aflag)
319		flags |= VEXPORT;
320	if (forcelocal && !(flags & (VNOSET | VNOLOCAL)))
321		mklocal(s);
322	vp = find_var(s, &vpp, &nlen);
323	if (vp != NULL) {
324		if (vp->flags & VREADONLY)
325			error("%.*s: is read only", vp->name_len, s);
326		if (flags & VNOSET)
327			return;
328		INTOFF;
329
330		if (vp->func && (flags & VNOFUNC) == 0)
331			(*vp->func)(s + vp->name_len + 1);
332
333		if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
334			ckfree(vp->text);
335
336		vp->flags &= ~(VTEXTFIXED|VSTACK|VUNSET);
337		vp->flags |= flags;
338		vp->text = s;
339
340		/*
341		 * We could roll this to a function, to handle it as
342		 * a regular variable function callback, but why bother?
343		 *
344		 * Note: this assumes iflag is not set to 1 initially.
345		 * As part of initvar(), this is called before arguments
346		 * are looked at.
347		 */
348		if ((vp == &vmpath || (vp == &vmail && ! mpathset())) &&
349		    iflag == 1)
350			chkmail(1);
351		if ((vp->flags & VEXPORT) && localevar(s)) {
352			change_env(s, 1);
353			(void) setlocale(LC_ALL, "");
354			updatecharset();
355		}
356		INTON;
357		return;
358	}
359	/* not found */
360	if (flags & VNOSET)
361		return;
362	vp = ckmalloc(sizeof (*vp));
363	vp->flags = flags;
364	vp->text = s;
365	vp->name_len = nlen;
366	vp->next = *vpp;
367	vp->func = NULL;
368	INTOFF;
369	*vpp = vp;
370	if ((vp->flags & VEXPORT) && localevar(s)) {
371		change_env(s, 1);
372		(void) setlocale(LC_ALL, "");
373		updatecharset();
374	}
375	INTON;
376}
377
378
379
380/*
381 * Process a linked list of variable assignments.
382 */
383
384void
385listsetvar(struct strlist *list, int flags)
386{
387	struct strlist *lp;
388
389	INTOFF;
390	for (lp = list ; lp ; lp = lp->next) {
391		setvareq(savestr(lp->text), flags);
392	}
393	INTON;
394}
395
396
397
398/*
399 * Find the value of a variable.  Returns NULL if not set.
400 */
401
402char *
403lookupvar(const char *name)
404{
405	struct var *v;
406
407	v = find_var(name, NULL, NULL);
408	if (v == NULL || v->flags & VUNSET)
409		return NULL;
410	return v->text + v->name_len + 1;
411}
412
413
414
415/*
416 * Search the environment of a builtin command.  If the second argument
417 * is nonzero, return the value of a variable even if it hasn't been
418 * exported.
419 */
420
421char *
422bltinlookup(const char *name, int doall)
423{
424	struct strlist *sp;
425	struct var *v;
426	char *result;
427
428	result = NULL;
429	for (sp = cmdenviron ; sp ; sp = sp->next) {
430		if (varequal(sp->text, name))
431			result = strchr(sp->text, '=') + 1;
432	}
433	if (result != NULL)
434		return result;
435
436	v = find_var(name, NULL, NULL);
437	if (v == NULL || v->flags & VUNSET ||
438	    (!doall && (v->flags & VEXPORT) == 0))
439		return NULL;
440	return v->text + v->name_len + 1;
441}
442
443
444/*
445 * Set up locale for a builtin (LANG/LC_* assignments).
446 */
447void
448bltinsetlocale(void)
449{
450	struct strlist *lp;
451	int act = 0;
452	char *loc, *locdef;
453	int i;
454
455	for (lp = cmdenviron ; lp ; lp = lp->next) {
456		if (localevar(lp->text)) {
457			act = 1;
458			break;
459		}
460	}
461	if (!act)
462		return;
463	loc = bltinlookup("LC_ALL", 0);
464	INTOFF;
465	if (loc != NULL) {
466		setlocale(LC_ALL, loc);
467		INTON;
468		updatecharset();
469		return;
470	}
471	locdef = bltinlookup("LANG", 0);
472	for (i = 0; locale_names[i] != NULL; i++) {
473		loc = bltinlookup(locale_names[i], 0);
474		if (loc == NULL)
475			loc = locdef;
476		if (loc != NULL)
477			setlocale(locale_categories[i], loc);
478	}
479	INTON;
480	updatecharset();
481}
482
483/*
484 * Undo the effect of bltinlocaleset().
485 */
486void
487bltinunsetlocale(void)
488{
489	struct strlist *lp;
490
491	INTOFF;
492	for (lp = cmdenviron ; lp ; lp = lp->next) {
493		if (localevar(lp->text)) {
494			setlocale(LC_ALL, "");
495			updatecharset();
496			return;
497		}
498	}
499	INTON;
500}
501
502/*
503 * Update the localeisutf8 flag.
504 */
505void
506updatecharset(void)
507{
508	char *charset;
509
510	charset = nl_langinfo(CODESET);
511	localeisutf8 = !strcmp(charset, "UTF-8");
512}
513
514void
515initcharset(void)
516{
517	updatecharset();
518	initial_localeisutf8 = localeisutf8;
519}
520
521/*
522 * Generate a list of exported variables.  This routine is used to construct
523 * the third argument to execve when executing a program.
524 */
525
526char **
527environment(void)
528{
529	int nenv;
530	struct var **vpp;
531	struct var *vp;
532	char **env, **ep;
533
534	nenv = 0;
535	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
536		for (vp = *vpp ; vp ; vp = vp->next)
537			if (vp->flags & VEXPORT)
538				nenv++;
539	}
540	ep = env = stalloc((nenv + 1) * sizeof *env);
541	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
542		for (vp = *vpp ; vp ; vp = vp->next)
543			if (vp->flags & VEXPORT)
544				*ep++ = vp->text;
545	}
546	*ep = NULL;
547	return env;
548}
549
550
551static int
552var_compare(const void *a, const void *b)
553{
554	const char *const *sa, *const *sb;
555
556	sa = a;
557	sb = b;
558	/*
559	 * This compares two var=value strings which creates a different
560	 * order from what you would probably expect.  POSIX is somewhat
561	 * ambiguous on what should be sorted exactly.
562	 */
563	return strcoll(*sa, *sb);
564}
565
566
567/*
568 * Command to list all variables which are set.  This is invoked from the
569 * set command when it is called without any options or operands.
570 */
571
572int
573showvarscmd(int argc __unused, char **argv __unused)
574{
575	struct var **vpp;
576	struct var *vp;
577	const char *s;
578	const char **vars;
579	int i, n;
580
581	/*
582	 * POSIX requires us to sort the variables.
583	 */
584	n = 0;
585	for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) {
586		for (vp = *vpp; vp; vp = vp->next) {
587			if (!(vp->flags & VUNSET))
588				n++;
589		}
590	}
591
592	INTOFF;
593	vars = ckmalloc(n * sizeof(*vars));
594	i = 0;
595	for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) {
596		for (vp = *vpp; vp; vp = vp->next) {
597			if (!(vp->flags & VUNSET))
598				vars[i++] = vp->text;
599		}
600	}
601
602	qsort(vars, n, sizeof(*vars), var_compare);
603	for (i = 0; i < n; i++) {
604		/*
605		 * Skip improper variable names so the output remains usable as
606		 * shell input.
607		 */
608		if (!isassignment(vars[i]))
609			continue;
610		s = strchr(vars[i], '=');
611		s++;
612		outbin(vars[i], s - vars[i], out1);
613		out1qstr(s);
614		out1c('\n');
615	}
616	ckfree(vars);
617	INTON;
618
619	return 0;
620}
621
622
623
624/*
625 * The export and readonly commands.
626 */
627
628int
629exportcmd(int argc __unused, char **argv)
630{
631	struct var **vpp;
632	struct var *vp;
633	char **ap;
634	char *name;
635	char *p;
636	char *cmdname;
637	int ch, values;
638	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
639
640	cmdname = argv[0];
641	values = 0;
642	while ((ch = nextopt("p")) != '\0') {
643		switch (ch) {
644		case 'p':
645			values = 1;
646			break;
647		}
648	}
649
650	if (values && *argptr != NULL)
651		error("-p requires no arguments");
652	if (*argptr != NULL) {
653		for (ap = argptr; (name = *ap) != NULL; ap++) {
654			if ((p = strchr(name, '=')) != NULL) {
655				p++;
656			} else {
657				vp = find_var(name, NULL, NULL);
658				if (vp != NULL) {
659					vp->flags |= flag;
660					if ((vp->flags & VEXPORT) && localevar(vp->text)) {
661						change_env(vp->text, 1);
662						(void) setlocale(LC_ALL, "");
663						updatecharset();
664					}
665					continue;
666				}
667			}
668			setvar(name, p, flag);
669		}
670	} else {
671		for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
672			for (vp = *vpp ; vp ; vp = vp->next) {
673				if (vp->flags & flag) {
674					if (values) {
675						/*
676						 * Skip improper variable names
677						 * so the output remains usable
678						 * as shell input.
679						 */
680						if (!isassignment(vp->text))
681							continue;
682						out1str(cmdname);
683						out1c(' ');
684					}
685					if (values && !(vp->flags & VUNSET)) {
686						outbin(vp->text,
687						    vp->name_len + 1, out1);
688						out1qstr(vp->text +
689						    vp->name_len + 1);
690					} else
691						outbin(vp->text, vp->name_len,
692						    out1);
693					out1c('\n');
694				}
695			}
696		}
697	}
698	return 0;
699}
700
701
702/*
703 * The "local" command.
704 */
705
706int
707localcmd(int argc __unused, char **argv __unused)
708{
709	char *name;
710
711	nextopt("");
712	if (! in_function())
713		error("Not in a function");
714	while ((name = *argptr++) != NULL) {
715		mklocal(name);
716	}
717	return 0;
718}
719
720
721/*
722 * Make a variable a local variable.  When a variable is made local, it's
723 * value and flags are saved in a localvar structure.  The saved values
724 * will be restored when the shell function returns.  We handle the name
725 * "-" as a special case.
726 */
727
728void
729mklocal(char *name)
730{
731	struct localvar *lvp;
732	struct var **vpp;
733	struct var *vp;
734
735	INTOFF;
736	lvp = ckmalloc(sizeof (struct localvar));
737	if (name[0] == '-' && name[1] == '\0') {
738		lvp->text = ckmalloc(sizeof optlist);
739		memcpy(lvp->text, optlist, sizeof optlist);
740		vp = NULL;
741	} else {
742		vp = find_var(name, &vpp, NULL);
743		if (vp == NULL) {
744			if (strchr(name, '='))
745				setvareq(savestr(name), VSTRFIXED | VNOLOCAL);
746			else
747				setvar(name, NULL, VSTRFIXED | VNOLOCAL);
748			vp = *vpp;	/* the new variable */
749			lvp->text = NULL;
750			lvp->flags = VUNSET;
751		} else {
752			lvp->text = vp->text;
753			lvp->flags = vp->flags;
754			vp->flags |= VSTRFIXED|VTEXTFIXED;
755			if (name[vp->name_len] == '=')
756				setvareq(savestr(name), VNOLOCAL);
757		}
758	}
759	lvp->vp = vp;
760	lvp->next = localvars;
761	localvars = lvp;
762	INTON;
763}
764
765
766/*
767 * Called after a function returns.
768 */
769
770void
771poplocalvars(void)
772{
773	struct localvar *lvp;
774	struct var *vp;
775
776	while ((lvp = localvars) != NULL) {
777		localvars = lvp->next;
778		vp = lvp->vp;
779		if (vp == NULL) {	/* $- saved */
780			memcpy(optlist, lvp->text, sizeof optlist);
781			ckfree(lvp->text);
782			optschanged();
783		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
784			(void)unsetvar(vp->text);
785		} else {
786			if ((vp->flags & VTEXTFIXED) == 0)
787				ckfree(vp->text);
788			vp->flags = lvp->flags;
789			vp->text = lvp->text;
790		}
791		ckfree(lvp);
792	}
793}
794
795
796int
797setvarcmd(int argc, char **argv)
798{
799	if (argc <= 2)
800		return unsetcmd(argc, argv);
801	else if (argc == 3)
802		setvar(argv[1], argv[2], 0);
803	else
804		error("too many arguments");
805	return 0;
806}
807
808
809/*
810 * The unset builtin command.
811 */
812
813int
814unsetcmd(int argc __unused, char **argv __unused)
815{
816	char **ap;
817	int i;
818	int flg_func = 0;
819	int flg_var = 0;
820	int ret = 0;
821
822	while ((i = nextopt("vf")) != '\0') {
823		if (i == 'f')
824			flg_func = 1;
825		else
826			flg_var = 1;
827	}
828	if (flg_func == 0 && flg_var == 0)
829		flg_var = 1;
830
831	for (ap = argptr; *ap ; ap++) {
832		if (flg_func)
833			ret |= unsetfunc(*ap);
834		if (flg_var)
835			ret |= unsetvar(*ap);
836	}
837	return ret;
838}
839
840
841/*
842 * Unset the specified variable.
843 */
844
845int
846unsetvar(const char *s)
847{
848	struct var **vpp;
849	struct var *vp;
850
851	vp = find_var(s, &vpp, NULL);
852	if (vp == NULL)
853		return (0);
854	if (vp->flags & VREADONLY)
855		return (1);
856	INTOFF;
857	if (vp->text[vp->name_len + 1] != '\0')
858		setvar(s, nullstr, 0);
859	if ((vp->flags & VEXPORT) && localevar(vp->text)) {
860		change_env(s, 0);
861		setlocale(LC_ALL, "");
862		updatecharset();
863	}
864	vp->flags &= ~VEXPORT;
865	vp->flags |= VUNSET;
866	if ((vp->flags & VSTRFIXED) == 0) {
867		if ((vp->flags & VTEXTFIXED) == 0)
868			ckfree(vp->text);
869		*vpp = vp->next;
870		ckfree(vp);
871	}
872	INTON;
873	return (0);
874}
875
876
877
878/*
879 * Returns true if the two strings specify the same variable.  The first
880 * variable name is terminated by '='; the second may be terminated by
881 * either '=' or '\0'.
882 */
883
884static int
885varequal(const char *p, const char *q)
886{
887	while (*p == *q++) {
888		if (*p++ == '=')
889			return 1;
890	}
891	if (*p == '=' && *(q - 1) == '\0')
892		return 1;
893	return 0;
894}
895
896/*
897 * Search for a variable.
898 * 'name' may be terminated by '=' or a NUL.
899 * vppp is set to the pointer to vp, or the list head if vp isn't found
900 * lenp is set to the number of characters in 'name'
901 */
902
903static struct var *
904find_var(const char *name, struct var ***vppp, int *lenp)
905{
906	unsigned int hashval;
907	int len;
908	struct var *vp, **vpp;
909	const char *p = name;
910
911	hashval = 0;
912	while (*p && *p != '=')
913		hashval = 2 * hashval + (unsigned char)*p++;
914	len = p - name;
915
916	if (lenp)
917		*lenp = len;
918	vpp = &vartab[hashval % VTABSIZE];
919	if (vppp)
920		*vppp = vpp;
921
922	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
923		if (vp->name_len != len)
924			continue;
925		if (memcmp(vp->text, name, len) != 0)
926			continue;
927		if (vppp)
928			*vppp = vpp;
929		return vp;
930	}
931	return NULL;
932}
933