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Last change on this file since 2515 was 2463, checked in by bird, 20 years ago
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1	/* $NetBSD: var.c,v 1.36 2004/10/06 10:23:43 enami Exp $ */
2
3	/*-
4	* Copyright (c) 1991, 1993
5	* The Regents of the University of California. All rights reserved.
6	*
7	* This code is derived from software contributed to Berkeley by
8	* Kenneth Almquist.
9	*
10	* Redistribution and use in source and binary forms, with or without
11	* modification, are permitted provided that the following conditions
12	* are met:
13	* 1. Redistributions of source code must retain the above copyright
14	* notice, this list of conditions and the following disclaimer.
15	* 2. Redistributions in binary form must reproduce the above copyright
16	* notice, this list of conditions and the following disclaimer in the
17	* documentation and/or other materials provided with the distribution.
18	* 3. Neither the name of the University nor the names of its contributors
19	* may be used to endorse or promote products derived from this software
20	* without specific prior written permission.
21	*
22	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32	* SUCH DAMAGE.
33	*/
34
35	#include <sys/cdefs.h>
36	#ifndef lint
37	#if 0
38	static char sccsid[] = "@(#)var.c 8.3 (Berkeley) 5/4/95";
39	#else
40	__RCSID("$NetBSD: var.c,v 1.36 2004/10/06 10:23:43 enami Exp $");
41	#endif
42	#endif /* not lint */
43
44	#include <unistd.h>
45	#include <stdlib.h>
46	#include <strings.h>
47	#include <paths.h>
48
49	#ifdef PC_OS2_LIBPATHS
50	#define INCL_BASE
51	#include <os2.h>
52
53	#ifndef LIBPATHSTRICT
54	#define LIBPATHSTRICT 3
55	#endif
56
57	extern APIRET
58	#ifdef APIENTRY
59	APIENTRY
60	#endif
61	DosQueryHeaderInfo(HMODULE hmod, ULONG ulIndex, PVOID pvBuffer, ULONG cbBuffer, ULONG ulSubFunction);
62	#define QHINF_EXEINFO 1 /* NE exeinfo. */
63	#define QHINF_READRSRCTBL 2 /* Reads from the resource table. */
64	#define QHINF_READFILE 3 /* Reads from the executable file. */
65	#define QHINF_LIBPATHLENGTH 4 /* Gets the libpath length. */
66	#define QHINF_LIBPATH 5 /* Gets the entire libpath. */
67	#define QHINF_FIXENTRY 6 /* NE only */
68	#define QHINF_STE 7 /* NE only */
69	#define QHINF_MAPSEL 8 /* NE only */
70
71	#endif
72
73
74	/*
75	* Shell variables.
76	*/
77
78	#include "shell.h"
79	#include "output.h"
80	#include "expand.h"
81	#include "nodes.h" /* for other headers */
82	#include "eval.h" /* defines cmdenviron */
83	#include "exec.h"
84	#include "syntax.h"
85	#include "options.h"
86	#include "mail.h"
87	#include "var.h"
88	#include "memalloc.h"
89	#include "error.h"
90	#include "mystring.h"
91	#include "parser.h"
92	#include "show.h"
93	#ifndef SMALL
94	#include "myhistedit.h"
95	#endif
96
97	#ifdef SMALL
98	#define VTABSIZE 39
99	#else
100	#define VTABSIZE 517
101	#endif
102
103
104	struct varinit {
105	struct var *var;
106	int flags;
107	const char *text;
108	void (func)(const char );
109	};
110
111
112	#if ATTY
113	struct var vatty;
114	#endif
115	#ifndef SMALL
116	struct var vhistsize;
117	struct var vterm;
118	#endif
119	struct var vifs;
120	struct var vmail;
121	struct var vmpath;
122	struct var vpath;
123	struct var vps1;
124	struct var vps2;
125	struct var vps4;
126	struct var vvers;
127	struct var voptind;
128
129	#ifdef PC_OS2_LIBPATHS
130	static struct var libpath_vars[4];
131	static const char *libpath_envs[4] = {"LIBPATH=", "BEGINLIBPATH=", "ENDLIBPATH=", "LIBPATHSTRICT="};
132	#endif
133
134	const struct varinit varinit[] = {
135	#if ATTY
136	{ &vatty, VSTRFIXED\|VTEXTFIXED\|VUNSET, "ATTY=",
137	NULL },
138	#endif
139	#ifndef SMALL
140	{ &vhistsize, VSTRFIXED\|VTEXTFIXED\|VUNSET, "HISTSIZE=",
141	sethistsize },
142	#endif
143	{ &vifs, VSTRFIXED\|VTEXTFIXED, "IFS= \t\n",
144	NULL },
145	{ &vmail, VSTRFIXED\|VTEXTFIXED\|VUNSET, "MAIL=",
146	NULL },
147	{ &vmpath, VSTRFIXED\|VTEXTFIXED\|VUNSET, "MAILPATH=",
148	NULL },
149	{ &vpath, VSTRFIXED\|VTEXTFIXED, "PATH=" _PATH_DEFPATH,
150	changepath },
151	/*
152	* vps1 depends on uid
153	*/
154	{ &vps2, VSTRFIXED\|VTEXTFIXED, "PS2=> ",
155	NULL },
156	{ &vps4, VSTRFIXED\|VTEXTFIXED, "PS4=+ ",
157	NULL },
158	#ifndef SMALL
159	{ &vterm, VSTRFIXED\|VTEXTFIXED\|VUNSET, "TERM=",
160	setterm },
161	#endif
162	{ &voptind, VSTRFIXED\|VTEXTFIXED\|VNOFUNC, "OPTIND=1",
163	getoptsreset },
164	{ NULL, 0, NULL,
165	NULL }
166	};
167
168	struct var *vartab[VTABSIZE];
169
170	STATIC int strequal(const char , const char );
171	STATIC struct var find_var(const char , struct var **, int );
172
173	/*
174	* Initialize the varable symbol tables and import the environment
175	*/
176
177	#ifdef mkinit
178	INCLUDE "var.h"
179	MKINIT char **environ;
180	INIT {
181	char **envp;
182
183	initvar();
184	for (envp = environ ; *envp ; envp++) {
185	if (strchr(*envp, '=')) {
186	setvareq(*envp, VEXPORT\|VTEXTFIXED);
187	}
188	}
189	}
190	#endif
191
192
193	/*
194	* This routine initializes the builtin variables. It is called when the
195	* shell is initialized and again when a shell procedure is spawned.
196	*/
197
198	void
199	initvar(void)
200	{
201	const struct varinit *ip;
202	struct var *vp;
203	struct var **vpp;
204
205	#ifdef PC_OS2_LIBPATHS
206	char *psz = ckmalloc(2048);
207	int rc;
208	int i;
209	for (i = 0; i < 4; i++)
210	{
211	libpath_vars[i].flags = VSTRFIXED \| VOS2LIBPATH;
212	libpath_vars[i].func = NULL;
213
214	if (i > 0)
215	rc = DosQueryExtLIBPATH(psz, i);
216	else
217	{
218	rc = DosQueryHeaderInfo(NULLHANDLE, 0, psz, 2048, QHINF_LIBPATH);
219	libpath_vars[i].flags \|= VREADONLY;
220	}
221	if (!rc && *psz)
222	{
223	int cch1 = strlen(libpath_envs[i]);
224	int cch2 = strlen(psz) + 1;
225	libpath_vars[i].text = ckmalloc(cch1 + cch2);
226	memcpy(libpath_vars[i].text, libpath_envs[i], cch1);
227	memcpy(libpath_vars[i].text + cch1, psz, cch2);
228	}
229	else
230	{
231	libpath_vars[i].flags \|= VUNSET \| VTEXTFIXED;
232	libpath_vars[i].text = (char*)libpath_envs[i];
233	}
234	if (find_var(libpath_vars[i].text, &vpp, &libpath_vars[i].name_len) != NULL)
235	continue;
236	libpath_vars[i].next = *vpp;
237	*vpp = &libpath_vars[i];
238	}
239	free(psz);
240	#endif
241
242	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
243	if (find_var(ip->text, &vpp, &vp->name_len) != NULL)
244	continue;
245	vp->next = *vpp;
246	*vpp = vp;
247	vp->text = strdup(ip->text);
248	vp->flags = ip->flags;
249	vp->func = ip->func;
250	}
251	/*
252	* PS1 depends on uid
253	*/
254	if (find_var("PS1", &vpp, &vps1.name_len) == NULL) {
255	vps1.next = *vpp;
256	*vpp = &vps1;
257	vps1.text = strdup(geteuid() ? "PS1=$ " : "PS1=# ");
258	vps1.flags = VSTRFIXED\|VTEXTFIXED;
259	}
260	}
261
262	/*
263	* Safe version of setvar, returns 1 on success 0 on failure.
264	*/
265
266	int
267	setvarsafe(const char name, const char val, int flags)
268	{
269	struct jmploc jmploc;
270	struct jmploc *volatile savehandler = handler;
271	int err = 0;
272	#ifdef __GNUC__
273	(void) &err;
274	#endif
275
276	if (setjmp(jmploc.loc))
277	err = 1;
278	else {
279	handler = &jmploc;
280	setvar(name, val, flags);
281	}
282	handler = savehandler;
283	return err;
284	}
285
286	/*
287	* Set the value of a variable. The flags argument is ored with the
288	* flags of the variable. If val is NULL, the variable is unset.
289	*/
290
291	void
292	setvar(const char name, const char val, int flags)
293	{
294	const char *p;
295	const char *q;
296	char *d;
297	int len;
298	int namelen;
299	char *nameeq;
300	int isbad;
301
302	isbad = 0;
303	p = name;
304	if (! is_name(*p))
305	isbad = 1;
306	p++;
307	for (;;) {
308	if (! is_in_name(*p)) {
309	if (p == '\0' \|\| p == '=')
310	break;
311	isbad = 1;
312	}
313	p++;
314	}
315	namelen = p - name;
316	if (isbad)
317	error("%.*s: bad variable name", namelen, name);
318	len = namelen + 2; /* 2 is space for '=' and '\0' */
319	if (val == NULL) {
320	flags \|= VUNSET;
321	} else {
322	len += strlen(val);
323	}
324	d = nameeq = ckmalloc(len);
325	q = name;
326	while (--namelen >= 0)
327	d++ = q++;
328	*d++ = '=';
329	*d = '\0';
330	if (val)
331	scopy(val, d);
332	setvareq(nameeq, flags);
333	}
334
335
336
337	/*
338	* Same as setvar except that the variable and value are passed in
339	* the first argument as name=value. Since the first argument will
340	* be actually stored in the table, it should not be a string that
341	* will go away.
342	*/
343
344	void
345	setvareq(char *s, int flags)
346	{
347	struct var vp, *vpp;
348	int nlen;
349
350	if (aflag)
351	flags \|= VEXPORT;
352	vp = find_var(s, &vpp, &nlen);
353	if (vp != NULL) {
354	if (vp->flags & VREADONLY)
355	error("%.*s: is read only", vp->name_len, s);
356	if (flags & VNOSET)
357	return;
358	INTOFF;
359
360	if (vp->func && (flags & VNOFUNC) == 0)
361	(*vp->func)(s + vp->name_len + 1);
362
363	if ((vp->flags & (VTEXTFIXED\|VSTACK)) == 0)
364	ckfree(vp->text);
365
366	vp->flags &= ~(VTEXTFIXED\|VSTACK\|VUNSET);
367	vp->flags \|= flags & ~VNOFUNC;
368	vp->text = s;
369	#ifdef PC_OS2_LIBPATHS
370	if ((vp->flags & VOS2LIBPATH) && (vp->flags & VEXPORT))
371	vp->flags &= ~VEXPORT;
372	#endif
373
374	/*
375	* We could roll this to a function, to handle it as
376	* a regular variable function callback, but why bother?
377	*/
378	if (vp == &vmpath \|\| (vp == &vmail && ! mpathset()))
379	chkmail(1);
380	INTON;
381	return;
382	}
383	/* not found */
384	if (flags & VNOSET)
385	return;
386	vp = ckmalloc(sizeof (*vp));
387	vp->flags = flags & ~VNOFUNC;
388	vp->text = s;
389	vp->name_len = nlen;
390	vp->next = *vpp;
391	vp->func = NULL;
392	*vpp = vp;
393	}
394
395
396
397	/*
398	* Process a linked list of variable assignments.
399	*/
400
401	void
402	listsetvar(struct strlist *list, int flags)
403	{
404	struct strlist *lp;
405
406	INTOFF;
407	for (lp = list ; lp ; lp = lp->next) {
408	setvareq(savestr(lp->text), flags);
409	}
410	INTON;
411	}
412
413	void
414	listmklocal(struct strlist *list, int flags)
415	{
416	struct strlist *lp;
417
418	for (lp = list ; lp ; lp = lp->next)
419	mklocal(lp->text, flags);
420	}
421
422
423	/*
424	* Find the value of a variable. Returns NULL if not set.
425	*/
426
427	char *
428	lookupvar(const char *name)
429	{
430	struct var *v;
431
432	v = find_var(name, NULL, NULL);
433	if (v == NULL \|\| v->flags & VUNSET)
434	return NULL;
435	return v->text + v->name_len + 1;
436	}
437
438
439
440	/*
441	* Search the environment of a builtin command. If the second argument
442	* is nonzero, return the value of a variable even if it hasn't been
443	* exported.
444	*/
445
446	char *
447	bltinlookup(const char *name, int doall)
448	{
449	struct strlist *sp;
450	struct var *v;
451
452	for (sp = cmdenviron ; sp ; sp = sp->next) {
453	if (strequal(sp->text, name))
454	return strchr(sp->text, '=') + 1;
455	}
456
457	v = find_var(name, NULL, NULL);
458
459	if (v == NULL \|\| v->flags & VUNSET \|\| (!doall && !(v->flags & VEXPORT)))
460	return NULL;
461	return v->text + v->name_len + 1;
462	}
463
464
465
466	/*
467	* Generate a list of exported variables. This routine is used to construct
468	* the third argument to execve when executing a program.
469	*/
470
471	char **
472	environment(void)
473	{
474	int nenv;
475	struct var **vpp;
476	struct var *vp;
477	char **env;
478	char **ep;
479
480	nenv = 0;
481	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
482	for (vp = *vpp ; vp ; vp = vp->next)
483	if (vp->flags & VEXPORT)
484	nenv++;
485	}
486	ep = env = stalloc((nenv + 1) * sizeof *env);
487	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
488	for (vp = *vpp ; vp ; vp = vp->next)
489	if (vp->flags & VEXPORT)
490	*ep++ = vp->text;
491	}
492	*ep = NULL;
493
494	#ifdef PC_OS2_LIBPATHS
495	/*
496	* Set the libpaths now as this is exec() time.
497	*/
498	for (nenv = 0; nenv < 3; nenv++)
499	DosSetExtLIBPATH(strchr(libpath_vars[nenv].text, '=') + 1, nenv);
500	#endif
501
502	return env;
503	}
504
505
506	/*
507	* Called when a shell procedure is invoked to clear out nonexported
508	* variables. It is also necessary to reallocate variables of with
509	* VSTACK set since these are currently allocated on the stack.
510	*/
511
512	#ifdef mkinit
513	void shprocvar(void);
514
515	SHELLPROC {
516	shprocvar();
517	}
518	#endif
519
520	void
521	shprocvar(void)
522	{
523	struct var **vpp;
524	struct var vp, *prev;
525
526	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
527	for (prev = vpp ; (vp = *prev) != NULL ; ) {
528	if ((vp->flags & VEXPORT) == 0) {
529	*prev = vp->next;
530	if ((vp->flags & VTEXTFIXED) == 0)
531	ckfree(vp->text);
532	if ((vp->flags & VSTRFIXED) == 0)
533	ckfree(vp);
534	} else {
535	if (vp->flags & VSTACK) {
536	vp->text = savestr(vp->text);
537	vp->flags &=~ VSTACK;
538	}
539	prev = &vp->next;
540	}
541	}
542	}
543	initvar();
544	}
545
546
547
548	/*
549	* Command to list all variables which are set. Currently this command
550	* is invoked from the set command when the set command is called without
551	* any variables.
552	*/
553
554	void
555	print_quoted(const char *p)
556	{
557	const char *q;
558
559	if (strcspn(p, "\|&;<>()$`\\\"' \t\n*?[]#~=%") == strlen(p)) {
560	out1fmt("%s", p);
561	return;
562	}
563	while (*p) {
564	if (*p == '\'') {
565	out1fmt("\\'");
566	p++;
567	continue;
568	}
569	q = index(p, '\'');
570	if (!q) {
571	out1fmt("'%s'", p );
572	return;
573	}
574	out1fmt("'%.*s'", (int)(q - p), p );
575	p = q;
576	}
577	}
578
579	static int
580	sort_var(const void v_v1, const void v_v2)
581	{
582	const struct var * const *v1 = v_v1;
583	const struct var * const *v2 = v_v2;
584
585	/* XXX Will anyone notice we include the '=' of the shorter name? */
586	return strcoll((v1)->text, (v2)->text);
587	}
588
589	/*
590	* POSIX requires that 'set' (but not export or readonly) output the
591	* variables in lexicographic order - by the locale's collating order (sigh).
592	* Maybe we could keep them in an ordered balanced binary tree
593	* instead of hashed lists.
594	* For now just roll 'em through qsort for printing...
595	*/
596
597	int
598	showvars(const char *name, int flag, int show_value)
599	{
600	struct var **vpp;
601	struct var *vp;
602	const char *p;
603
604	static struct var *list; / static in case we are interrupted */
605	static int list_len;
606	int count = 0;
607
608	if (!list) {
609	list_len = 32;
610	list = ckmalloc(list_len * sizeof *list);
611	}
612
613	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
614	for (vp = *vpp ; vp ; vp = vp->next) {
615	if (flag && !(vp->flags & flag))
616	continue;
617	if (vp->flags & VUNSET && !(show_value & 2))
618	continue;
619	if (count >= list_len) {
620	list = ckrealloc(list,
621	(list_len << 1) * sizeof *list);
622	list_len <<= 1;
623	}
624	list[count++] = vp;
625	}
626	}
627
628	qsort(list, count, sizeof *list, sort_var);
629
630	for (vpp = list; count--; vpp++) {
631	vp = *vpp;
632	if (name)
633	out1fmt("%s ", name);
634	for (p = vp->text ; *p != '=' ; p++)
635	out1c(*p);
636	if (!(vp->flags & VUNSET) && show_value) {
637	out1fmt("=");
638	print_quoted(++p);
639	}
640	out1c('\n');
641	}
642	return 0;
643	}
644
645
646
647	/*
648	* The export and readonly commands.
649	*/
650
651	int
652	exportcmd(int argc, char **argv)
653	{
654	struct var *vp;
655	char *name;
656	const char *p;
657	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
658	int pflag;
659
660	pflag = nextopt("p") == 'p' ? 3 : 0;
661	if (argc <= 1 \|\| pflag) {
662	showvars( pflag ? argv[0] : 0, flag, pflag );
663	return 0;
664	}
665
666	while ((name = *argptr++) != NULL) {
667	if ((p = strchr(name, '=')) != NULL) {
668	p++;
669	} else {
670	vp = find_var(name, NULL, NULL);
671	if (vp != NULL) {
672	vp->flags \|= flag;
673	continue;
674	}
675	}
676	setvar(name, p, flag);
677	}
678	return 0;
679	}
680
681
682	/*
683	* The "local" command.
684	*/
685
686	int
687	localcmd(int argc, char **argv)
688	{
689	char *name;
690
691	if (! in_function())
692	error("Not in a function");
693	while ((name = *argptr++) != NULL) {
694	mklocal(name, 0);
695	}
696	return 0;
697	}
698
699
700	/*
701	* Make a variable a local variable. When a variable is made local, it's
702	* value and flags are saved in a localvar structure. The saved values
703	* will be restored when the shell function returns. We handle the name
704	* "-" as a special case.
705	*/
706
707	void
708	mklocal(const char *name, int flags)
709	{
710	struct localvar *lvp;
711	struct var **vpp;
712	struct var *vp;
713
714	INTOFF;
715	lvp = ckmalloc(sizeof (struct localvar));
716	if (name[0] == '-' && name[1] == '\0') {
717	char *p;
718	p = ckmalloc(sizeof_optlist);
719	lvp->text = memcpy(p, optlist, sizeof_optlist);
720	vp = NULL;
721	} else {
722	vp = find_var(name, &vpp, NULL);
723	if (vp == NULL) {
724	if (strchr(name, '='))
725	setvareq(savestr(name), VSTRFIXED\|flags);
726	else
727	setvar(name, NULL, VSTRFIXED\|flags);
728	vp = vpp; / the new variable */
729	lvp->text = NULL;
730	lvp->flags = VUNSET;
731	} else {
732	lvp->text = vp->text;
733	lvp->flags = vp->flags;
734	vp->flags \|= VSTRFIXED\|VTEXTFIXED;
735	if (name[vp->name_len] == '=')
736	setvareq(savestr(name), flags);
737	}
738	}
739	lvp->vp = vp;
740	lvp->next = localvars;
741	localvars = lvp;
742	INTON;
743	}
744
745
746	/*
747	* Called after a function returns.
748	*/
749
750	void
751	poplocalvars(void)
752	{
753	struct localvar *lvp;
754	struct var *vp;
755
756	while ((lvp = localvars) != NULL) {
757	localvars = lvp->next;
758	vp = lvp->vp;
759	TRACE(("poplocalvar %s", vp ? vp->text : "-"));
760	if (vp == NULL) { /* $- saved */
761	memcpy(optlist, lvp->text, sizeof_optlist);
762	ckfree(lvp->text);
763	} else if ((lvp->flags & (VUNSET\|VSTRFIXED)) == VUNSET) {
764	(void)unsetvar(vp->text, 0);
765	} else {
766	if (vp->func && (vp->flags & VNOFUNC) == 0)
767	(*vp->func)(lvp->text + vp->name_len + 1);
768	if ((vp->flags & VTEXTFIXED) == 0)
769	ckfree(vp->text);
770	vp->flags = lvp->flags;
771	vp->text = lvp->text;
772	}
773	ckfree(lvp);
774	}
775	}
776
777
778	int
779	setvarcmd(int argc, char **argv)
780	{
781	if (argc <= 2)
782	return unsetcmd(argc, argv);
783	else if (argc == 3)
784	setvar(argv[1], argv[2], 0);
785	else
786	error("List assignment not implemented");
787	return 0;
788	}
789
790
791	/*
792	* The unset builtin command. We unset the function before we unset the
793	* variable to allow a function to be unset when there is a readonly variable
794	* with the same name.
795	*/
796
797	int
798	unsetcmd(int argc, char **argv)
799	{
800	char **ap;
801	int i;
802	int flg_func = 0;
803	int flg_var = 0;
804	int ret = 0;
805
806	while ((i = nextopt("evf")) != '\0') {
807	if (i == 'f')
808	flg_func = 1;
809	else
810	flg_var = i;
811	}
812	if (flg_func == 0 && flg_var == 0)
813	flg_var = 1;
814
815	for (ap = argptr; *ap ; ap++) {
816	if (flg_func)
817	ret \|= unsetfunc(*ap);
818	if (flg_var)
819	ret \|= unsetvar(*ap, flg_var == 'e');
820	}
821	return ret;
822	}
823
824
825	/*
826	* Unset the specified variable.
827	*/
828
829	int
830	unsetvar(const char *s, int unexport)
831	{
832	struct var **vpp;
833	struct var *vp;
834
835	vp = find_var(s, &vpp, NULL);
836	if (vp == NULL)
837	return 1;
838
839	if (vp->flags & VREADONLY)
840	return (1);
841
842	INTOFF;
843	if (unexport) {
844	vp->flags &= ~VEXPORT;
845	} else {
846	if (vp->text[vp->name_len + 1] != '\0')
847	setvar(s, nullstr, 0);
848	vp->flags &= ~VEXPORT;
849	vp->flags \|= VUNSET;
850	if ((vp->flags & VSTRFIXED) == 0) {
851	if ((vp->flags & VTEXTFIXED) == 0)
852	ckfree(vp->text);
853	*vpp = vp->next;
854	ckfree(vp);
855	}
856	}
857	INTON;
858	return 0;
859	}
860
861
862	/*
863	* Returns true if the two strings specify the same varable. The first
864	* variable name is terminated by '='; the second may be terminated by
865	* either '=' or '\0'.
866	*/
867
868	STATIC int
869	strequal(const char p, const char q)
870	{
871	while (p == q++) {
872	if (*p++ == '=')
873	return 1;
874	}
875	if (p == '=' && (q - 1) == '\0')
876	return 1;
877	return 0;
878	}
879
880	/*
881	* Search for a variable.
882	* 'name' may be terminated by '=' or a NUL.
883	* vppp is set to the pointer to vp, or the list head if vp isn't found
884	* lenp is set to the number of charactets in 'name'
885	*/
886
887	STATIC struct var *
888	find_var(const char name, struct var *vppp, int lenp)
889	{
890	unsigned int hashval;
891	int len;
892	struct var vp, *vpp;
893	const char *p = name;
894
895	hashval = 0;
896	while (p && p != '=')
897	hashval = 2 * hashval + (unsigned char)*p++;
898	len = p - name;
899
900	if (lenp)
901	*lenp = len;
902	vpp = &vartab[hashval % VTABSIZE];
903	if (vppp)
904	*vppp = vpp;
905
906	for (vp = vpp ; vp ; vpp = &vp->next, vp = vpp) {
907	if (vp->name_len != len)
908	continue;
909	if (memcmp(vp->text, name, len) != 0)
910	continue;
911	if (vppp)
912	*vppp = vpp;
913	return vp;
914	}
915	return NULL;
916	}

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