var.c revision 254339 
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: head/bin/sh/var.c 254339 2013-08-14 21:59:48Z jilles $");
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 vppid;
92struct var vps1;
93struct var vps2;
94struct var vps4;
95struct var vvers;
96static struct var voptind;
97struct var vdisvfork;
98
99int forcelocal;
100
101static const struct varinit varinit[] = {
102#ifndef NO_HISTORY
103	{ &vhistsize,	VUNSET,				"HISTSIZE=",
104	  sethistsize },
105#endif
106	{ &vifs,	0,				"IFS= \t\n",
107	  NULL },
108	{ &vmail,	VUNSET,				"MAIL=",
109	  NULL },
110	{ &vmpath,	VUNSET,				"MAILPATH=",
111	  NULL },
112	{ &vpath,	0,				"PATH=" _PATH_DEFPATH,
113	  changepath },
114	{ &vppid,	VUNSET,				"PPID=",
115	  NULL },
116	/*
117	 * vps1 depends on uid
118	 */
119	{ &vps2,	0,				"PS2=> ",
120	  NULL },
121	{ &vps4,	0,				"PS4=+ ",
122	  NULL },
123#ifndef NO_HISTORY
124	{ &vterm,	VUNSET,				"TERM=",
125	  setterm },
126#endif
127	{ &voptind,	0,				"OPTIND=1",
128	  getoptsreset },
129	{ &vdisvfork,	VUNSET,				"SH_DISABLE_VFORK=",
130	  NULL },
131	{ NULL,	0,				NULL,
132	  NULL }
133};
134
135static struct var *vartab[VTABSIZE];
136
137static const char *const locale_names[7] = {
138	"LC_COLLATE", "LC_CTYPE", "LC_MONETARY",
139	"LC_NUMERIC", "LC_TIME", "LC_MESSAGES", NULL
140};
141static const int locale_categories[7] = {
142	LC_COLLATE, LC_CTYPE, LC_MONETARY, LC_NUMERIC, LC_TIME, LC_MESSAGES, 0
143};
144
145static int varequal(const char *, const char *);
146static struct var *find_var(const char *, struct var ***, int *);
147static int localevar(const char *);
148
149extern char **environ;
150
151/*
152 * This routine initializes the builtin variables and imports the environment.
153 * It is called when the shell is initialized.
154 */
155
156void
157initvar(void)
158{
159	char ppid[20];
160	const struct varinit *ip;
161	struct var *vp;
162	struct var **vpp;
163	char **envp;
164
165	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
166		if (find_var(ip->text, &vpp, &vp->name_len) != NULL)
167			continue;
168		vp->next = *vpp;
169		*vpp = vp;
170		vp->text = __DECONST(char *, ip->text);
171		vp->flags = ip->flags | VSTRFIXED | VTEXTFIXED;
172		vp->func = ip->func;
173	}
174	/*
175	 * PS1 depends on uid
176	 */
177	if (find_var("PS1", &vpp, &vps1.name_len) == NULL) {
178		vps1.next = *vpp;
179		*vpp = &vps1;
180		vps1.text = __DECONST(char *, geteuid() ? "PS1=$ " : "PS1=# ");
181		vps1.flags = VSTRFIXED|VTEXTFIXED;
182	}
183	if ((vppid.flags & VEXPORT) == 0) {
184		fmtstr(ppid, sizeof(ppid), "%d", (int)getppid());
185		setvarsafe("PPID", ppid, 0);
186	}
187	for (envp = environ ; *envp ; envp++) {
188		if (strchr(*envp, '=')) {
189			setvareq(*envp, VEXPORT|VTEXTFIXED);
190		}
191	}
192}
193
194/*
195 * Safe version of setvar, returns 1 on success 0 on failure.
196 */
197
198int
199setvarsafe(const char *name, const char *val, int flags)
200{
201	struct jmploc jmploc;
202	struct jmploc *const savehandler = handler;
203	int err = 0;
204	int inton;
205
206	inton = is_int_on();
207	if (setjmp(jmploc.loc))
208		err = 1;
209	else {
210		handler = &jmploc;
211		setvar(name, val, flags);
212	}
213	handler = savehandler;
214	SETINTON(inton);
215	return err;
216}
217
218/*
219 * Set the value of a variable.  The flags argument is stored with the
220 * flags of the variable.  If val is NULL, the variable is unset.
221 */
222
223void
224setvar(const char *name, const char *val, int flags)
225{
226	const char *p;
227	int len;
228	int namelen;
229	char *nameeq;
230	int isbad;
231
232	isbad = 0;
233	p = name;
234	if (! is_name(*p))
235		isbad = 1;
236	p++;
237	for (;;) {
238		if (! is_in_name(*p)) {
239			if (*p == '\0' || *p == '=')
240				break;
241			isbad = 1;
242		}
243		p++;
244	}
245	namelen = p - name;
246	if (isbad)
247		error("%.*s: bad variable name", namelen, name);
248	len = namelen + 2;		/* 2 is space for '=' and '\0' */
249	if (val == NULL) {
250		flags |= VUNSET;
251	} else {
252		len += strlen(val);
253	}
254	nameeq = ckmalloc(len);
255	memcpy(nameeq, name, namelen);
256	nameeq[namelen] = '=';
257	if (val)
258		scopy(val, nameeq + namelen + 1);
259	else
260		nameeq[namelen + 1] = '\0';
261	setvareq(nameeq, flags);
262}
263
264static int
265localevar(const char *s)
266{
267	const char *const *ss;
268
269	if (*s != 'L')
270		return 0;
271	if (varequal(s + 1, "ANG"))
272		return 1;
273	if (strncmp(s + 1, "C_", 2) != 0)
274		return 0;
275	if (varequal(s + 3, "ALL"))
276		return 1;
277	for (ss = locale_names; *ss ; ss++)
278		if (varequal(s + 3, *ss + 3))
279			return 1;
280	return 0;
281}
282
283
284/*
285 * Sets/unsets an environment variable from a pointer that may actually be a
286 * pointer into environ where the string should not be manipulated.
287 */
288static void
289change_env(const char *s, int set)
290{
291	char *eqp;
292	char *ss;
293
294	ss = savestr(s);
295	if ((eqp = strchr(ss, '=')) != NULL)
296		*eqp = '\0';
297	if (set && eqp != NULL)
298		(void) setenv(ss, eqp + 1, 1);
299	else
300		(void) unsetenv(ss);
301	ckfree(ss);
302
303	return;
304}
305
306
307/*
308 * Same as setvar except that the variable and value are passed in
309 * the first argument as name=value.  Since the first argument will
310 * be actually stored in the table, it should not be a string that
311 * will go away.
312 */
313
314void
315setvareq(char *s, int flags)
316{
317	struct var *vp, **vpp;
318	int nlen;
319
320	if (aflag)
321		flags |= VEXPORT;
322	if (forcelocal && !(flags & (VNOSET | VNOLOCAL)))
323		mklocal(s);
324	vp = find_var(s, &vpp, &nlen);
325	if (vp != NULL) {
326		if (vp->flags & VREADONLY)
327			error("%.*s: is read only", vp->name_len, s);
328		if (flags & VNOSET)
329			return;
330		INTOFF;
331
332		if (vp->func && (flags & VNOFUNC) == 0)
333			(*vp->func)(s + vp->name_len + 1);
334
335		if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
336			ckfree(vp->text);
337
338		vp->flags &= ~(VTEXTFIXED|VSTACK|VUNSET);
339		vp->flags |= flags;
340		vp->text = s;
341
342		/*
343		 * We could roll this to a function, to handle it as
344		 * a regular variable function callback, but why bother?
345		 *
346		 * Note: this assumes iflag is not set to 1 initially.
347		 * As part of initvar(), this is called before arguments
348		 * are looked at.
349		 */
350		if ((vp == &vmpath || (vp == &vmail && ! mpathset())) &&
351		    iflag == 1)
352			chkmail(1);
353		if ((vp->flags & VEXPORT) && localevar(s)) {
354			change_env(s, 1);
355			(void) setlocale(LC_ALL, "");
356			updatecharset();
357		}
358		INTON;
359		return;
360	}
361	/* not found */
362	if (flags & VNOSET)
363		return;
364	vp = ckmalloc(sizeof (*vp));
365	vp->flags = flags;
366	vp->text = s;
367	vp->name_len = nlen;
368	vp->next = *vpp;
369	vp->func = NULL;
370	INTOFF;
371	*vpp = vp;
372	if ((vp->flags & VEXPORT) && localevar(s)) {
373		change_env(s, 1);
374		(void) setlocale(LC_ALL, "");
375		updatecharset();
376	}
377	INTON;
378}
379
380
381
382/*
383 * Process a linked list of variable assignments.
384 */
385
386void
387listsetvar(struct strlist *list, int flags)
388{
389	struct strlist *lp;
390
391	INTOFF;
392	for (lp = list ; lp ; lp = lp->next) {
393		setvareq(savestr(lp->text), flags);
394	}
395	INTON;
396}
397
398
399
400/*
401 * Find the value of a variable.  Returns NULL if not set.
402 */
403
404char *
405lookupvar(const char *name)
406{
407	struct var *v;
408
409	v = find_var(name, NULL, NULL);
410	if (v == NULL || v->flags & VUNSET)
411		return NULL;
412	return v->text + v->name_len + 1;
413}
414
415
416
417/*
418 * Search the environment of a builtin command.  If the second argument
419 * is nonzero, return the value of a variable even if it hasn't been
420 * exported.
421 */
422
423char *
424bltinlookup(const char *name, int doall)
425{
426	struct strlist *sp;
427	struct var *v;
428	char *result;
429
430	result = NULL;
431	for (sp = cmdenviron ; sp ; sp = sp->next) {
432		if (varequal(sp->text, name))
433			result = strchr(sp->text, '=') + 1;
434	}
435	if (result != NULL)
436		return result;
437
438	v = find_var(name, NULL, NULL);
439	if (v == NULL || v->flags & VUNSET ||
440	    (!doall && (v->flags & VEXPORT) == 0))
441		return NULL;
442	return v->text + v->name_len + 1;
443}
444
445
446/*
447 * Set up locale for a builtin (LANG/LC_* assignments).
448 */
449void
450bltinsetlocale(void)
451{
452	struct strlist *lp;
453	int act = 0;
454	char *loc, *locdef;
455	int i;
456
457	for (lp = cmdenviron ; lp ; lp = lp->next) {
458		if (localevar(lp->text)) {
459			act = 1;
460			break;
461		}
462	}
463	if (!act)
464		return;
465	loc = bltinlookup("LC_ALL", 0);
466	INTOFF;
467	if (loc != NULL) {
468		setlocale(LC_ALL, loc);
469		INTON;
470		updatecharset();
471		return;
472	}
473	locdef = bltinlookup("LANG", 0);
474	for (i = 0; locale_names[i] != NULL; i++) {
475		loc = bltinlookup(locale_names[i], 0);
476		if (loc == NULL)
477			loc = locdef;
478		if (loc != NULL)
479			setlocale(locale_categories[i], loc);
480	}
481	INTON;
482	updatecharset();
483}
484
485/*
486 * Undo the effect of bltinlocaleset().
487 */
488void
489bltinunsetlocale(void)
490{
491	struct strlist *lp;
492
493	INTOFF;
494	for (lp = cmdenviron ; lp ; lp = lp->next) {
495		if (localevar(lp->text)) {
496			setlocale(LC_ALL, "");
497			updatecharset();
498			return;
499		}
500	}
501	INTON;
502}
503
504/*
505 * Update the localeisutf8 flag.
506 */
507void
508updatecharset(void)
509{
510	char *charset;
511
512	charset = nl_langinfo(CODESET);
513	localeisutf8 = !strcmp(charset, "UTF-8");
514}
515
516void
517initcharset(void)
518{
519	updatecharset();
520	initial_localeisutf8 = localeisutf8;
521}
522
523/*
524 * Generate a list of exported variables.  This routine is used to construct
525 * the third argument to execve when executing a program.
526 */
527
528char **
529environment(void)
530{
531	int nenv;
532	struct var **vpp;
533	struct var *vp;
534	char **env, **ep;
535
536	nenv = 0;
537	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
538		for (vp = *vpp ; vp ; vp = vp->next)
539			if (vp->flags & VEXPORT)
540				nenv++;
541	}
542	ep = env = stalloc((nenv + 1) * sizeof *env);
543	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
544		for (vp = *vpp ; vp ; vp = vp->next)
545			if (vp->flags & VEXPORT)
546				*ep++ = vp->text;
547	}
548	*ep = NULL;
549	return env;
550}
551
552
553static int
554var_compare(const void *a, const void *b)
555{
556	const char *const *sa, *const *sb;
557
558	sa = a;
559	sb = b;
560	/*
561	 * This compares two var=value strings which creates a different
562	 * order from what you would probably expect.  POSIX is somewhat
563	 * ambiguous on what should be sorted exactly.
564	 */
565	return strcoll(*sa, *sb);
566}
567
568
569/*
570 * Command to list all variables which are set.  This is invoked from the
571 * set command when it is called without any options or operands.
572 */
573
574int
575showvarscmd(int argc __unused, char **argv __unused)
576{
577	struct var **vpp;
578	struct var *vp;
579	const char *s;
580	const char **vars;
581	int i, n;
582
583	/*
584	 * POSIX requires us to sort the variables.
585	 */
586	n = 0;
587	for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) {
588		for (vp = *vpp; vp; vp = vp->next) {
589			if (!(vp->flags & VUNSET))
590				n++;
591		}
592	}
593
594	INTOFF;
595	vars = ckmalloc(n * sizeof(*vars));
596	i = 0;
597	for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) {
598		for (vp = *vpp; vp; vp = vp->next) {
599			if (!(vp->flags & VUNSET))
600				vars[i++] = vp->text;
601		}
602	}
603
604	qsort(vars, n, sizeof(*vars), var_compare);
605	for (i = 0; i < n; i++) {
606		/*
607		 * Skip improper variable names so the output remains usable as
608		 * shell input.
609		 */
610		if (!isassignment(vars[i]))
611			continue;
612		s = strchr(vars[i], '=');
613		s++;
614		outbin(vars[i], s - vars[i], out1);
615		out1qstr(s);
616		out1c('\n');
617	}
618	ckfree(vars);
619	INTON;
620
621	return 0;
622}
623
624
625
626/*
627 * The export and readonly commands.
628 */
629
630int
631exportcmd(int argc __unused, char **argv)
632{
633	struct var **vpp;
634	struct var *vp;
635	char **ap;
636	char *name;
637	char *p;
638	char *cmdname;
639	int ch, values;
640	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
641
642	cmdname = argv[0];
643	values = 0;
644	while ((ch = nextopt("p")) != '\0') {
645		switch (ch) {
646		case 'p':
647			values = 1;
648			break;
649		}
650	}
651
652	if (values && *argptr != NULL)
653		error("-p requires no arguments");
654	if (*argptr != NULL) {
655		for (ap = argptr; (name = *ap) != NULL; ap++) {
656			if ((p = strchr(name, '=')) != NULL) {
657				p++;
658			} else {
659				vp = find_var(name, NULL, NULL);
660				if (vp != NULL) {
661					vp->flags |= flag;
662					if ((vp->flags & VEXPORT) && localevar(vp->text)) {
663						change_env(vp->text, 1);
664						(void) setlocale(LC_ALL, "");
665						updatecharset();
666					}
667					continue;
668				}
669			}
670			setvar(name, p, flag);
671		}
672	} else {
673		for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
674			for (vp = *vpp ; vp ; vp = vp->next) {
675				if (vp->flags & flag) {
676					if (values) {
677						/*
678						 * Skip improper variable names
679						 * so the output remains usable
680						 * as shell input.
681						 */
682						if (!isassignment(vp->text))
683							continue;
684						out1str(cmdname);
685						out1c(' ');
686					}
687					if (values && !(vp->flags & VUNSET)) {
688						outbin(vp->text,
689						    vp->name_len + 1, out1);
690						out1qstr(vp->text +
691						    vp->name_len + 1);
692					} else
693						outbin(vp->text, vp->name_len,
694						    out1);
695					out1c('\n');
696				}
697			}
698		}
699	}
700	return 0;
701}
702
703
704/*
705 * The "local" command.
706 */
707
708int
709localcmd(int argc __unused, char **argv __unused)
710{
711	char *name;
712
713	nextopt("");
714	if (! in_function())
715		error("Not in a function");
716	while ((name = *argptr++) != NULL) {
717		mklocal(name);
718	}
719	return 0;
720}
721
722
723/*
724 * Make a variable a local variable.  When a variable is made local, it's
725 * value and flags are saved in a localvar structure.  The saved values
726 * will be restored when the shell function returns.  We handle the name
727 * "-" as a special case.
728 */
729
730void
731mklocal(char *name)
732{
733	struct localvar *lvp;
734	struct var **vpp;
735	struct var *vp;
736
737	INTOFF;
738	lvp = ckmalloc(sizeof (struct localvar));
739	if (name[0] == '-' && name[1] == '\0') {
740		lvp->text = ckmalloc(sizeof optlist);
741		memcpy(lvp->text, optlist, sizeof optlist);
742		vp = NULL;
743	} else {
744		vp = find_var(name, &vpp, NULL);
745		if (vp == NULL) {
746			if (strchr(name, '='))
747				setvareq(savestr(name), VSTRFIXED | VNOLOCAL);
748			else
749				setvar(name, NULL, VSTRFIXED | VNOLOCAL);
750			vp = *vpp;	/* the new variable */
751			lvp->text = NULL;
752			lvp->flags = VUNSET;
753		} else {
754			lvp->text = vp->text;
755			lvp->flags = vp->flags;
756			vp->flags |= VSTRFIXED|VTEXTFIXED;
757			if (name[vp->name_len] == '=')
758				setvareq(savestr(name), VNOLOCAL);
759		}
760	}
761	lvp->vp = vp;
762	lvp->next = localvars;
763	localvars = lvp;
764	INTON;
765}
766
767
768/*
769 * Called after a function returns.
770 */
771
772void
773poplocalvars(void)
774{
775	struct localvar *lvp;
776	struct var *vp;
777
778	while ((lvp = localvars) != NULL) {
779		localvars = lvp->next;
780		vp = lvp->vp;
781		if (vp == NULL) {	/* $- saved */
782			memcpy(optlist, lvp->text, sizeof optlist);
783			ckfree(lvp->text);
784			optschanged();
785		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
786			(void)unsetvar(vp->text);
787		} else {
788			if ((vp->flags & VTEXTFIXED) == 0)
789				ckfree(vp->text);
790			vp->flags = lvp->flags;
791			vp->text = lvp->text;
792		}
793		ckfree(lvp);
794	}
795}
796
797
798int
799setvarcmd(int argc, char **argv)
800{
801	if (argc <= 2)
802		return unsetcmd(argc, argv);
803	else if (argc == 3)
804		setvar(argv[1], argv[2], 0);
805	else
806		error("too many arguments");
807	return 0;
808}
809
810
811/*
812 * The unset builtin command.
813 */
814
815int
816unsetcmd(int argc __unused, char **argv __unused)
817{
818	char **ap;
819	int i;
820	int flg_func = 0;
821	int flg_var = 0;
822	int ret = 0;
823
824	while ((i = nextopt("vf")) != '\0') {
825		if (i == 'f')
826			flg_func = 1;
827		else
828			flg_var = 1;
829	}
830	if (flg_func == 0 && flg_var == 0)
831		flg_var = 1;
832
833	for (ap = argptr; *ap ; ap++) {
834		if (flg_func)
835			ret |= unsetfunc(*ap);
836		if (flg_var)
837			ret |= unsetvar(*ap);
838	}
839	return ret;
840}
841
842
843/*
844 * Unset the specified variable.
845 */
846
847int
848unsetvar(const char *s)
849{
850	struct var **vpp;
851	struct var *vp;
852
853	vp = find_var(s, &vpp, NULL);
854	if (vp == NULL)
855		return (0);
856	if (vp->flags & VREADONLY)
857		return (1);
858	INTOFF;
859	if (vp->text[vp->name_len + 1] != '\0')
860		setvar(s, nullstr, 0);
861	if ((vp->flags & VEXPORT) && localevar(vp->text)) {
862		change_env(s, 0);
863		setlocale(LC_ALL, "");
864		updatecharset();
865	}
866	vp->flags &= ~VEXPORT;
867	vp->flags |= VUNSET;
868	if ((vp->flags & VSTRFIXED) == 0) {
869		if ((vp->flags & VTEXTFIXED) == 0)
870			ckfree(vp->text);
871		*vpp = vp->next;
872		ckfree(vp);
873	}
874	INTON;
875	return (0);
876}
877
878
879
880/*
881 * Returns true if the two strings specify the same variable.  The first
882 * variable name is terminated by '='; the second may be terminated by
883 * either '=' or '\0'.
884 */
885
886static int
887varequal(const char *p, const char *q)
888{
889	while (*p == *q++) {
890		if (*p++ == '=')
891			return 1;
892	}
893	if (*p == '=' && *(q - 1) == '\0')
894		return 1;
895	return 0;
896}
897
898/*
899 * Search for a variable.
900 * 'name' may be terminated by '=' or a NUL.
901 * vppp is set to the pointer to vp, or the list head if vp isn't found
902 * lenp is set to the number of characters in 'name'
903 */
904
905static struct var *
906find_var(const char *name, struct var ***vppp, int *lenp)
907{
908	unsigned int hashval;
909	int len;
910	struct var *vp, **vpp;
911	const char *p = name;
912
913	hashval = 0;
914	while (*p && *p != '=')
915		hashval = 2 * hashval + (unsigned char)*p++;
916	len = p - name;
917
918	if (lenp)
919		*lenp = len;
920	vpp = &vartab[hashval % VTABSIZE];
921	if (vppp)
922		*vppp = vpp;
923
924	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
925		if (vp->name_len != len)
926			continue;
927		if (memcmp(vp->text, name, len) != 0)
928			continue;
929		if (vppp)
930			*vppp = vpp;
931		return vp;
932	}
933	return NULL;
934}
935