xref: /freebsd/bin/sh/var.c (revision 38f0b757fd84d17d0fc24739a7cda160c4516d81) 
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
35 static char sccsid[] = "@(#)var.c	8.3 (Berkeley) 5/4/95";
36 #endif
37 #endif /* not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
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 
75 struct varinit {
76 	struct var *var;
77 	int flags;
78 	const char *text;
79 	void (*func)(const char *);
80 };
81 
82 
83 #ifndef NO_HISTORY
84 struct var vhistsize;
85 struct var vterm;
86 #endif
87 struct var vifs;
88 struct var vmail;
89 struct var vmpath;
90 struct var vpath;
91 struct var vps1;
92 struct var vps2;
93 struct var vps4;
94 static struct var voptind;
95 struct var vdisvfork;
96 
97 int forcelocal;
98 
99 static 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 
131 static struct var *vartab[VTABSIZE];
132 
133 static const char *const locale_names[7] = {
134 	"LC_COLLATE", "LC_CTYPE", "LC_MONETARY",
135 	"LC_NUMERIC", "LC_TIME", "LC_MESSAGES", NULL
136 };
137 static const int locale_categories[7] = {
138 	LC_COLLATE, LC_CTYPE, LC_MONETARY, LC_NUMERIC, LC_TIME, LC_MESSAGES, 0
139 };
140 
141 static int varequal(const char *, const char *);
142 static struct var *find_var(const char *, struct var ***, int *);
143 static int localevar(const char *);
144 
145 extern 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 
152 void
153 initvar(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 
193 int
194 setvarsafe(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 
218 void
219 setvar(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 	INTOFF;
253 	nameeq = ckmalloc(len);
254 	memcpy(nameeq, name, namelen);
255 	nameeq[namelen] = '=';
256 	if (val)
257 		memcpy(nameeq + namelen + 1, val, vallen + 1);
258 	else
259 		nameeq[namelen + 1] = '\0';
260 	setvareq(nameeq, flags);
261 	INTON;
262 }
263 
264 static int
265 localevar(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  */
288 static void
289 change_env(const char *s, int set)
290 {
291 	char *eqp;
292 	char *ss;
293 
294 	INTOFF;
295 	ss = savestr(s);
296 	if ((eqp = strchr(ss, '=')) != NULL)
297 		*eqp = '\0';
298 	if (set && eqp != NULL)
299 		(void) setenv(ss, eqp + 1, 1);
300 	else
301 		(void) unsetenv(ss);
302 	ckfree(ss);
303 	INTON;
304 
305 	return;
306 }
307 
308 
309 /*
310  * Same as setvar except that the variable and value are passed in
311  * the first argument as name=value.  Since the first argument will
312  * be actually stored in the table, it should not be a string that
313  * will go away.
314  */
315 
316 void
317 setvareq(char *s, int flags)
318 {
319 	struct var *vp, **vpp;
320 	int nlen;
321 
322 	if (aflag)
323 		flags |= VEXPORT;
324 	if (forcelocal && !(flags & (VNOSET | VNOLOCAL)))
325 		mklocal(s);
326 	vp = find_var(s, &vpp, &nlen);
327 	if (vp != NULL) {
328 		if (vp->flags & VREADONLY) {
329 			if ((flags & (VTEXTFIXED|VSTACK)) == 0)
330 				ckfree(s);
331 			error("%.*s: is read only", vp->name_len, s);
332 		}
333 		if (flags & VNOSET) {
334 			if ((flags & (VTEXTFIXED|VSTACK)) == 0)
335 				ckfree(s);
336 			return;
337 		}
338 		INTOFF;
339 
340 		if (vp->func && (flags & VNOFUNC) == 0)
341 			(*vp->func)(s + vp->name_len + 1);
342 
343 		if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
344 			ckfree(vp->text);
345 
346 		vp->flags &= ~(VTEXTFIXED|VSTACK|VUNSET);
347 		vp->flags |= flags;
348 		vp->text = s;
349 
350 		/*
351 		 * We could roll this to a function, to handle it as
352 		 * a regular variable function callback, but why bother?
353 		 *
354 		 * Note: this assumes iflag is not set to 1 initially.
355 		 * As part of initvar(), this is called before arguments
356 		 * are looked at.
357 		 */
358 		if ((vp == &vmpath || (vp == &vmail && ! mpathset())) &&
359 		    iflag == 1)
360 			chkmail(1);
361 		if ((vp->flags & VEXPORT) && localevar(s)) {
362 			change_env(s, 1);
363 			(void) setlocale(LC_ALL, "");
364 			updatecharset();
365 		}
366 		INTON;
367 		return;
368 	}
369 	/* not found */
370 	if (flags & VNOSET) {
371 		if ((flags & (VTEXTFIXED|VSTACK)) == 0)
372 			ckfree(s);
373 		return;
374 	}
375 	INTOFF;
376 	vp = ckmalloc(sizeof (*vp));
377 	vp->flags = flags;
378 	vp->text = s;
379 	vp->name_len = nlen;
380 	vp->next = *vpp;
381 	vp->func = NULL;
382 	*vpp = vp;
383 	if ((vp->flags & VEXPORT) && localevar(s)) {
384 		change_env(s, 1);
385 		(void) setlocale(LC_ALL, "");
386 		updatecharset();
387 	}
388 	INTON;
389 }
390 
391 
392 
393 /*
394  * Process a linked list of variable assignments.
395  */
396 
397 void
398 listsetvar(struct strlist *list, int flags)
399 {
400 	struct strlist *lp;
401 
402 	INTOFF;
403 	for (lp = list ; lp ; lp = lp->next) {
404 		setvareq(savestr(lp->text), flags);
405 	}
406 	INTON;
407 }
408 
409 
410 
411 /*
412  * Find the value of a variable.  Returns NULL if not set.
413  */
414 
415 char *
416 lookupvar(const char *name)
417 {
418 	struct var *v;
419 
420 	v = find_var(name, NULL, NULL);
421 	if (v == NULL || v->flags & VUNSET)
422 		return NULL;
423 	return v->text + v->name_len + 1;
424 }
425 
426 
427 
428 /*
429  * Search the environment of a builtin command.  If the second argument
430  * is nonzero, return the value of a variable even if it hasn't been
431  * exported.
432  */
433 
434 char *
435 bltinlookup(const char *name, int doall)
436 {
437 	struct strlist *sp;
438 	struct var *v;
439 	char *result;
440 
441 	result = NULL;
442 	for (sp = cmdenviron ; sp ; sp = sp->next) {
443 		if (varequal(sp->text, name))
444 			result = strchr(sp->text, '=') + 1;
445 	}
446 	if (result != NULL)
447 		return result;
448 
449 	v = find_var(name, NULL, NULL);
450 	if (v == NULL || v->flags & VUNSET ||
451 	    (!doall && (v->flags & VEXPORT) == 0))
452 		return NULL;
453 	return v->text + v->name_len + 1;
454 }
455 
456 
457 /*
458  * Set up locale for a builtin (LANG/LC_* assignments).
459  */
460 void
461 bltinsetlocale(void)
462 {
463 	struct strlist *lp;
464 	int act = 0;
465 	char *loc, *locdef;
466 	int i;
467 
468 	for (lp = cmdenviron ; lp ; lp = lp->next) {
469 		if (localevar(lp->text)) {
470 			act = 1;
471 			break;
472 		}
473 	}
474 	if (!act)
475 		return;
476 	loc = bltinlookup("LC_ALL", 0);
477 	INTOFF;
478 	if (loc != NULL) {
479 		setlocale(LC_ALL, loc);
480 		INTON;
481 		updatecharset();
482 		return;
483 	}
484 	locdef = bltinlookup("LANG", 0);
485 	for (i = 0; locale_names[i] != NULL; i++) {
486 		loc = bltinlookup(locale_names[i], 0);
487 		if (loc == NULL)
488 			loc = locdef;
489 		if (loc != NULL)
490 			setlocale(locale_categories[i], loc);
491 	}
492 	INTON;
493 	updatecharset();
494 }
495 
496 /*
497  * Undo the effect of bltinlocaleset().
498  */
499 void
500 bltinunsetlocale(void)
501 {
502 	struct strlist *lp;
503 
504 	INTOFF;
505 	for (lp = cmdenviron ; lp ; lp = lp->next) {
506 		if (localevar(lp->text)) {
507 			setlocale(LC_ALL, "");
508 			updatecharset();
509 			return;
510 		}
511 	}
512 	INTON;
513 }
514 
515 /*
516  * Update the localeisutf8 flag.
517  */
518 void
519 updatecharset(void)
520 {
521 	char *charset;
522 
523 	charset = nl_langinfo(CODESET);
524 	localeisutf8 = !strcmp(charset, "UTF-8");
525 }
526 
527 void
528 initcharset(void)
529 {
530 	updatecharset();
531 	initial_localeisutf8 = localeisutf8;
532 }
533 
534 /*
535  * Generate a list of exported variables.  This routine is used to construct
536  * the third argument to execve when executing a program.
537  */
538 
539 char **
540 environment(void)
541 {
542 	int nenv;
543 	struct var **vpp;
544 	struct var *vp;
545 	char **env, **ep;
546 
547 	nenv = 0;
548 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
549 		for (vp = *vpp ; vp ; vp = vp->next)
550 			if (vp->flags & VEXPORT)
551 				nenv++;
552 	}
553 	ep = env = stalloc((nenv + 1) * sizeof *env);
554 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
555 		for (vp = *vpp ; vp ; vp = vp->next)
556 			if (vp->flags & VEXPORT)
557 				*ep++ = vp->text;
558 	}
559 	*ep = NULL;
560 	return env;
561 }
562 
563 
564 static int
565 var_compare(const void *a, const void *b)
566 {
567 	const char *const *sa, *const *sb;
568 
569 	sa = a;
570 	sb = b;
571 	/*
572 	 * This compares two var=value strings which creates a different
573 	 * order from what you would probably expect.  POSIX is somewhat
574 	 * ambiguous on what should be sorted exactly.
575 	 */
576 	return strcoll(*sa, *sb);
577 }
578 
579 
580 /*
581  * Command to list all variables which are set.  This is invoked from the
582  * set command when it is called without any options or operands.
583  */
584 
585 int
586 showvarscmd(int argc __unused, char **argv __unused)
587 {
588 	struct var **vpp;
589 	struct var *vp;
590 	const char *s;
591 	const char **vars;
592 	int i, n;
593 
594 	/*
595 	 * POSIX requires us to sort the variables.
596 	 */
597 	n = 0;
598 	for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) {
599 		for (vp = *vpp; vp; vp = vp->next) {
600 			if (!(vp->flags & VUNSET))
601 				n++;
602 		}
603 	}
604 
605 	INTOFF;
606 	vars = ckmalloc(n * sizeof(*vars));
607 	i = 0;
608 	for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) {
609 		for (vp = *vpp; vp; vp = vp->next) {
610 			if (!(vp->flags & VUNSET))
611 				vars[i++] = vp->text;
612 		}
613 	}
614 
615 	qsort(vars, n, sizeof(*vars), var_compare);
616 	for (i = 0; i < n; i++) {
617 		/*
618 		 * Skip improper variable names so the output remains usable as
619 		 * shell input.
620 		 */
621 		if (!isassignment(vars[i]))
622 			continue;
623 		s = strchr(vars[i], '=');
624 		s++;
625 		outbin(vars[i], s - vars[i], out1);
626 		out1qstr(s);
627 		out1c('\n');
628 	}
629 	ckfree(vars);
630 	INTON;
631 
632 	return 0;
633 }
634 
635 
636 
637 /*
638  * The export and readonly commands.
639  */
640 
641 int
642 exportcmd(int argc __unused, char **argv)
643 {
644 	struct var **vpp;
645 	struct var *vp;
646 	char **ap;
647 	char *name;
648 	char *p;
649 	char *cmdname;
650 	int ch, values;
651 	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
652 
653 	cmdname = argv[0];
654 	values = 0;
655 	while ((ch = nextopt("p")) != '\0') {
656 		switch (ch) {
657 		case 'p':
658 			values = 1;
659 			break;
660 		}
661 	}
662 
663 	if (values && *argptr != NULL)
664 		error("-p requires no arguments");
665 	if (*argptr != NULL) {
666 		for (ap = argptr; (name = *ap) != NULL; ap++) {
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 					if ((vp->flags & VEXPORT) && localevar(vp->text)) {
674 						change_env(vp->text, 1);
675 						(void) setlocale(LC_ALL, "");
676 						updatecharset();
677 					}
678 					continue;
679 				}
680 			}
681 			setvar(name, p, flag);
682 		}
683 	} else {
684 		for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
685 			for (vp = *vpp ; vp ; vp = vp->next) {
686 				if (vp->flags & flag) {
687 					if (values) {
688 						/*
689 						 * Skip improper variable names
690 						 * so the output remains usable
691 						 * as shell input.
692 						 */
693 						if (!isassignment(vp->text))
694 							continue;
695 						out1str(cmdname);
696 						out1c(' ');
697 					}
698 					if (values && !(vp->flags & VUNSET)) {
699 						outbin(vp->text,
700 						    vp->name_len + 1, out1);
701 						out1qstr(vp->text +
702 						    vp->name_len + 1);
703 					} else
704 						outbin(vp->text, vp->name_len,
705 						    out1);
706 					out1c('\n');
707 				}
708 			}
709 		}
710 	}
711 	return 0;
712 }
713 
714 
715 /*
716  * The "local" command.
717  */
718 
719 int
720 localcmd(int argc __unused, char **argv __unused)
721 {
722 	char *name;
723 
724 	nextopt("");
725 	if (! in_function())
726 		error("Not in a function");
727 	while ((name = *argptr++) != NULL) {
728 		mklocal(name);
729 	}
730 	return 0;
731 }
732 
733 
734 /*
735  * Make a variable a local variable.  When a variable is made local, it's
736  * value and flags are saved in a localvar structure.  The saved values
737  * will be restored when the shell function returns.  We handle the name
738  * "-" as a special case.
739  */
740 
741 void
742 mklocal(char *name)
743 {
744 	struct localvar *lvp;
745 	struct var **vpp;
746 	struct var *vp;
747 
748 	INTOFF;
749 	lvp = ckmalloc(sizeof (struct localvar));
750 	if (name[0] == '-' && name[1] == '\0') {
751 		lvp->text = ckmalloc(sizeof optlist);
752 		memcpy(lvp->text, optlist, sizeof optlist);
753 		vp = NULL;
754 	} else {
755 		vp = find_var(name, &vpp, NULL);
756 		if (vp == NULL) {
757 			if (strchr(name, '='))
758 				setvareq(savestr(name), VSTRFIXED | VNOLOCAL);
759 			else
760 				setvar(name, NULL, VSTRFIXED | VNOLOCAL);
761 			vp = *vpp;	/* the new variable */
762 			lvp->text = NULL;
763 			lvp->flags = VUNSET;
764 		} else {
765 			lvp->text = vp->text;
766 			lvp->flags = vp->flags;
767 			vp->flags |= VSTRFIXED|VTEXTFIXED;
768 			if (name[vp->name_len] == '=')
769 				setvareq(savestr(name), VNOLOCAL);
770 		}
771 	}
772 	lvp->vp = vp;
773 	lvp->next = localvars;
774 	localvars = lvp;
775 	INTON;
776 }
777 
778 
779 /*
780  * Called after a function returns.
781  */
782 
783 void
784 poplocalvars(void)
785 {
786 	struct localvar *lvp;
787 	struct var *vp;
788 
789 	INTOFF;
790 	while ((lvp = localvars) != NULL) {
791 		localvars = lvp->next;
792 		vp = lvp->vp;
793 		if (vp == NULL) {	/* $- saved */
794 			memcpy(optlist, lvp->text, sizeof optlist);
795 			ckfree(lvp->text);
796 			optschanged();
797 		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
798 			(void)unsetvar(vp->text);
799 		} else {
800 			if ((vp->flags & VTEXTFIXED) == 0)
801 				ckfree(vp->text);
802 			vp->flags = lvp->flags;
803 			vp->text = lvp->text;
804 		}
805 		ckfree(lvp);
806 	}
807 	INTON;
808 }
809 
810 
811 int
812 setvarcmd(int argc, char **argv)
813 {
814 	if (argc <= 2)
815 		return unsetcmd(argc, argv);
816 	else if (argc == 3)
817 		setvar(argv[1], argv[2], 0);
818 	else
819 		error("too many arguments");
820 	return 0;
821 }
822 
823 
824 /*
825  * The unset builtin command.
826  */
827 
828 int
829 unsetcmd(int argc __unused, char **argv __unused)
830 {
831 	char **ap;
832 	int i;
833 	int flg_func = 0;
834 	int flg_var = 0;
835 	int ret = 0;
836 
837 	while ((i = nextopt("vf")) != '\0') {
838 		if (i == 'f')
839 			flg_func = 1;
840 		else
841 			flg_var = 1;
842 	}
843 	if (flg_func == 0 && flg_var == 0)
844 		flg_var = 1;
845 
846 	INTOFF;
847 	for (ap = argptr; *ap ; ap++) {
848 		if (flg_func)
849 			ret |= unsetfunc(*ap);
850 		if (flg_var)
851 			ret |= unsetvar(*ap);
852 	}
853 	INTON;
854 	return ret;
855 }
856 
857 
858 /*
859  * Unset the specified variable.
860  * Called with interrupts off.
861  */
862 
863 int
864 unsetvar(const char *s)
865 {
866 	struct var **vpp;
867 	struct var *vp;
868 
869 	vp = find_var(s, &vpp, NULL);
870 	if (vp == NULL)
871 		return (0);
872 	if (vp->flags & VREADONLY)
873 		return (1);
874 	if (vp->text[vp->name_len + 1] != '\0')
875 		setvar(s, nullstr, 0);
876 	if ((vp->flags & VEXPORT) && localevar(vp->text)) {
877 		change_env(s, 0);
878 		setlocale(LC_ALL, "");
879 		updatecharset();
880 	}
881 	vp->flags &= ~VEXPORT;
882 	vp->flags |= VUNSET;
883 	if ((vp->flags & VSTRFIXED) == 0) {
884 		if ((vp->flags & VTEXTFIXED) == 0)
885 			ckfree(vp->text);
886 		*vpp = vp->next;
887 		ckfree(vp);
888 	}
889 	return (0);
890 }
891 
892 
893 
894 /*
895  * Returns true if the two strings specify the same variable.  The first
896  * variable name is terminated by '='; the second may be terminated by
897  * either '=' or '\0'.
898  */
899 
900 static int
901 varequal(const char *p, const char *q)
902 {
903 	while (*p == *q++) {
904 		if (*p++ == '=')
905 			return 1;
906 	}
907 	if (*p == '=' && *(q - 1) == '\0')
908 		return 1;
909 	return 0;
910 }
911 
912 /*
913  * Search for a variable.
914  * 'name' may be terminated by '=' or a NUL.
915  * vppp is set to the pointer to vp, or the list head if vp isn't found
916  * lenp is set to the number of characters in 'name'
917  */
918 
919 static struct var *
920 find_var(const char *name, struct var ***vppp, int *lenp)
921 {
922 	unsigned int hashval;
923 	int len;
924 	struct var *vp, **vpp;
925 	const char *p = name;
926 
927 	hashval = 0;
928 	while (*p && *p != '=')
929 		hashval = 2 * hashval + (unsigned char)*p++;
930 	len = p - name;
931 
932 	if (lenp)
933 		*lenp = len;
934 	vpp = &vartab[hashval % VTABSIZE];
935 	if (vppp)
936 		*vppp = vpp;
937 
938 	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
939 		if (vp->name_len != len)
940 			continue;
941 		if (memcmp(vp->text, name, len) != 0)
942 			continue;
943 		if (vppp)
944 			*vppp = vpp;
945 		return vp;
946 	}
947 	return NULL;
948 }
949