xref: /freebsd/bin/sh/var.c (revision d0b2dbfa0ecf2bbc9709efc5e20baf8e4b44bbbf) 
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
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 #ifndef lint
36 #if 0
37 static char sccsid[] = "@(#)var.c	8.3 (Berkeley) 5/4/95";
38 #endif
39 #endif /* not lint */
40 #include <sys/cdefs.h>
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 #ifndef VTABSIZE
73 #define VTABSIZE 39
74 #endif
75 
76 
77 struct varinit {
78 	struct var *var;
79 	int flags;
80 	const char *text;
81 	void (*func)(const char *);
82 };
83 
84 
85 #ifndef NO_HISTORY
86 struct var vhistsize;
87 struct var vterm;
88 #endif
89 struct var vifs;
90 struct var vmail;
91 struct var vmpath;
92 struct var vpath;
93 struct var vps1;
94 struct var vps2;
95 struct var vps4;
96 static struct var voptind;
97 struct var vdisvfork;
98 
99 struct localvar *localvars;
100 int forcelocal;
101 
102 static const struct varinit varinit[] = {
103 #ifndef NO_HISTORY
104 	{ &vhistsize,	VUNSET,				"HISTSIZE=",
105 	  sethistsize },
106 #endif
107 	{ &vifs,	0,				"IFS= \t\n",
108 	  NULL },
109 	{ &vmail,	VUNSET,				"MAIL=",
110 	  NULL },
111 	{ &vmpath,	VUNSET,				"MAILPATH=",
112 	  NULL },
113 	{ &vpath,	0,				"PATH=" _PATH_DEFPATH,
114 	  changepath },
115 	/*
116 	 * vps1 depends on uid
117 	 */
118 	{ &vps2,	0,				"PS2=> ",
119 	  NULL },
120 	{ &vps4,	0,				"PS4=+ ",
121 	  NULL },
122 #ifndef NO_HISTORY
123 	{ &vterm,	VUNSET,				"TERM=",
124 	  setterm },
125 #endif
126 	{ &voptind,	0,				"OPTIND=1",
127 	  getoptsreset },
128 	{ &vdisvfork,	VUNSET,				"SH_DISABLE_VFORK=",
129 	  NULL },
130 	{ NULL,	0,				NULL,
131 	  NULL }
132 };
133 
134 static struct var *vartab[VTABSIZE];
135 
136 static const char *const locale_names[7] = {
137 	"LC_COLLATE", "LC_CTYPE", "LC_MONETARY",
138 	"LC_NUMERIC", "LC_TIME", "LC_MESSAGES", NULL
139 };
140 static const int locale_categories[7] = {
141 	LC_COLLATE, LC_CTYPE, LC_MONETARY, LC_NUMERIC, LC_TIME, LC_MESSAGES, 0
142 };
143 
144 static int varequal(const char *, const char *);
145 static struct var *find_var(const char *, struct var ***, int *);
146 static int localevar(const char *);
147 static void setvareq_const(const char *s, int flags);
148 
149 extern 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 
156 void
157 initvar(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 	fmtstr(ppid, sizeof(ppid), "%d", (int)getppid());
184 	setvarsafe("PPID", ppid, 0);
185 	for (envp = environ ; *envp ; envp++) {
186 		if (strchr(*envp, '=')) {
187 			setvareq(*envp, VEXPORT|VTEXTFIXED);
188 		}
189 	}
190 	setvareq_const("OPTIND=1", 0);
191 	setvareq_const("IFS= \t\n", 0);
192 }
193 
194 /*
195  * Safe version of setvar, returns 1 on success 0 on failure.
196  */
197 
198 int
199 setvarsafe(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 
223 void
224 setvar(const char *name, const char *val, int flags)
225 {
226 	const char *p;
227 	size_t len;
228 	size_t namelen;
229 	size_t vallen;
230 	char *nameeq;
231 	int isbad;
232 
233 	isbad = 0;
234 	p = name;
235 	if (! is_name(*p))
236 		isbad = 1;
237 	p++;
238 	for (;;) {
239 		if (! is_in_name(*p)) {
240 			if (*p == '\0' || *p == '=')
241 				break;
242 			isbad = 1;
243 		}
244 		p++;
245 	}
246 	namelen = p - name;
247 	if (isbad)
248 		error("%.*s: bad variable name", (int)namelen, name);
249 	len = namelen + 2;		/* 2 is space for '=' and '\0' */
250 	if (val == NULL) {
251 		flags |= VUNSET;
252 		vallen = 0;
253 	} else {
254 		vallen = strlen(val);
255 		len += vallen;
256 	}
257 	INTOFF;
258 	nameeq = ckmalloc(len);
259 	memcpy(nameeq, name, namelen);
260 	nameeq[namelen] = '=';
261 	if (val)
262 		memcpy(nameeq + namelen + 1, val, vallen + 1);
263 	else
264 		nameeq[namelen + 1] = '\0';
265 	setvareq(nameeq, flags);
266 	INTON;
267 }
268 
269 static int
270 localevar(const char *s)
271 {
272 	const char *const *ss;
273 
274 	if (*s != 'L')
275 		return 0;
276 	if (varequal(s + 1, "ANG"))
277 		return 1;
278 	if (strncmp(s + 1, "C_", 2) != 0)
279 		return 0;
280 	if (varequal(s + 3, "ALL"))
281 		return 1;
282 	for (ss = locale_names; *ss ; ss++)
283 		if (varequal(s + 3, *ss + 3))
284 			return 1;
285 	return 0;
286 }
287 
288 
289 /*
290  * Sets/unsets an environment variable from a pointer that may actually be a
291  * pointer into environ where the string should not be manipulated.
292  */
293 static void
294 change_env(const char *s, int set)
295 {
296 	char *eqp;
297 	char *ss;
298 
299 	INTOFF;
300 	ss = savestr(s);
301 	if ((eqp = strchr(ss, '=')) != NULL)
302 		*eqp = '\0';
303 	if (set && eqp != NULL)
304 		(void) setenv(ss, eqp + 1, 1);
305 	else
306 		(void) unsetenv(ss);
307 	ckfree(ss);
308 	INTON;
309 
310 	return;
311 }
312 
313 
314 /*
315  * Same as setvar except that the variable and value are passed in
316  * the first argument as name=value.  Since the first argument will
317  * be actually stored in the table, it should not be a string that
318  * will go away.
319  */
320 
321 void
322 setvareq(char *s, int flags)
323 {
324 	struct var *vp, **vpp;
325 	int nlen;
326 
327 	if (aflag)
328 		flags |= VEXPORT;
329 	if (forcelocal && !(flags & (VNOSET | VNOLOCAL)))
330 		mklocal(s);
331 	vp = find_var(s, &vpp, &nlen);
332 	if (vp != NULL) {
333 		if (vp->flags & VREADONLY) {
334 			if ((flags & (VTEXTFIXED|VSTACK)) == 0)
335 				ckfree(s);
336 			error("%.*s: is read only", vp->name_len, vp->text);
337 		}
338 		if (flags & VNOSET) {
339 			if ((flags & (VTEXTFIXED|VSTACK)) == 0)
340 				ckfree(s);
341 			return;
342 		}
343 		INTOFF;
344 
345 		if (vp->func && (flags & VNOFUNC) == 0)
346 			(*vp->func)(s + vp->name_len + 1);
347 
348 		if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
349 			ckfree(vp->text);
350 
351 		vp->flags &= ~(VTEXTFIXED|VSTACK|VUNSET);
352 		vp->flags |= flags;
353 		vp->text = s;
354 
355 		/*
356 		 * We could roll this to a function, to handle it as
357 		 * a regular variable function callback, but why bother?
358 		 *
359 		 * Note: this assumes iflag is not set to 1 initially.
360 		 * As part of initvar(), this is called before arguments
361 		 * are looked at.
362 		 */
363 		if ((vp == &vmpath || (vp == &vmail && ! mpathset())) &&
364 		    iflag == 1)
365 			chkmail(1);
366 		if ((vp->flags & VEXPORT) && localevar(s)) {
367 			change_env(s, 1);
368 			(void) setlocale(LC_ALL, "");
369 			updatecharset();
370 		}
371 		INTON;
372 		return;
373 	}
374 	/* not found */
375 	if (flags & VNOSET) {
376 		if ((flags & (VTEXTFIXED|VSTACK)) == 0)
377 			ckfree(s);
378 		return;
379 	}
380 	INTOFF;
381 	vp = ckmalloc(sizeof (*vp));
382 	vp->flags = flags;
383 	vp->text = s;
384 	vp->name_len = nlen;
385 	vp->next = *vpp;
386 	vp->func = NULL;
387 	*vpp = vp;
388 	if ((vp->flags & VEXPORT) && localevar(s)) {
389 		change_env(s, 1);
390 		(void) setlocale(LC_ALL, "");
391 		updatecharset();
392 	}
393 	INTON;
394 }
395 
396 
397 static void
398 setvareq_const(const char *s, int flags)
399 {
400 	setvareq(__DECONST(char *, s), flags | VTEXTFIXED);
401 }
402 
403 
404 /*
405  * Process a linked list of variable assignments.
406  */
407 
408 void
409 listsetvar(struct arglist *list, int flags)
410 {
411 	int i;
412 
413 	INTOFF;
414 	for (i = 0; i < list->count; i++)
415 		setvareq(savestr(list->args[i]), flags);
416 	INTON;
417 }
418 
419 
420 
421 /*
422  * Find the value of a variable.  Returns NULL if not set.
423  */
424 
425 char *
426 lookupvar(const char *name)
427 {
428 	struct var *v;
429 
430 	v = find_var(name, NULL, NULL);
431 	if (v == NULL || v->flags & VUNSET)
432 		return NULL;
433 	return v->text + v->name_len + 1;
434 }
435 
436 
437 
438 /*
439  * Search the environment of a builtin command.  If the second argument
440  * is nonzero, return the value of a variable even if it hasn't been
441  * exported.
442  */
443 
444 char *
445 bltinlookup(const char *name, int doall)
446 {
447 	struct var *v;
448 	char *result;
449 	int i;
450 
451 	result = NULL;
452 	if (cmdenviron) for (i = 0; i < cmdenviron->count; i++) {
453 		if (varequal(cmdenviron->args[i], name))
454 			result = strchr(cmdenviron->args[i], '=') + 1;
455 	}
456 	if (result != NULL)
457 		return result;
458 
459 	v = find_var(name, NULL, NULL);
460 	if (v == NULL || v->flags & VUNSET ||
461 	    (!doall && (v->flags & VEXPORT) == 0))
462 		return NULL;
463 	return v->text + v->name_len + 1;
464 }
465 
466 
467 /*
468  * Set up locale for a builtin (LANG/LC_* assignments).
469  */
470 void
471 bltinsetlocale(void)
472 {
473 	int act = 0;
474 	char *loc, *locdef;
475 	int i;
476 
477 	if (cmdenviron) for (i = 0; i < cmdenviron->count; i++) {
478 		if (localevar(cmdenviron->args[i])) {
479 			act = 1;
480 			break;
481 		}
482 	}
483 	if (!act)
484 		return;
485 	loc = bltinlookup("LC_ALL", 0);
486 	INTOFF;
487 	if (loc != NULL) {
488 		setlocale(LC_ALL, loc);
489 		INTON;
490 		updatecharset();
491 		return;
492 	}
493 	locdef = bltinlookup("LANG", 0);
494 	for (i = 0; locale_names[i] != NULL; i++) {
495 		loc = bltinlookup(locale_names[i], 0);
496 		if (loc == NULL)
497 			loc = locdef;
498 		if (loc != NULL)
499 			setlocale(locale_categories[i], loc);
500 	}
501 	INTON;
502 	updatecharset();
503 }
504 
505 /*
506  * Undo the effect of bltinlocaleset().
507  */
508 void
509 bltinunsetlocale(void)
510 {
511 	int i;
512 
513 	INTOFF;
514 	if (cmdenviron) for (i = 0; i < cmdenviron->count; i++) {
515 		if (localevar(cmdenviron->args[i])) {
516 			setlocale(LC_ALL, "");
517 			updatecharset();
518 			break;
519 		}
520 	}
521 	INTON;
522 }
523 
524 /*
525  * Update the localeisutf8 flag.
526  */
527 void
528 updatecharset(void)
529 {
530 	char *charset;
531 
532 	charset = nl_langinfo(CODESET);
533 	localeisutf8 = !strcmp(charset, "UTF-8");
534 }
535 
536 void
537 initcharset(void)
538 {
539 	updatecharset();
540 	initial_localeisutf8 = localeisutf8;
541 }
542 
543 /*
544  * Generate a list of exported variables.  This routine is used to construct
545  * the third argument to execve when executing a program.
546  */
547 
548 char **
549 environment(void)
550 {
551 	int nenv;
552 	struct var **vpp;
553 	struct var *vp;
554 	char **env, **ep;
555 
556 	nenv = 0;
557 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
558 		for (vp = *vpp ; vp ; vp = vp->next)
559 			if ((vp->flags & (VEXPORT|VUNSET)) == VEXPORT)
560 				nenv++;
561 	}
562 	ep = env = stalloc((nenv + 1) * sizeof *env);
563 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
564 		for (vp = *vpp ; vp ; vp = vp->next)
565 			if ((vp->flags & (VEXPORT|VUNSET)) == VEXPORT)
566 				*ep++ = vp->text;
567 	}
568 	*ep = NULL;
569 	return env;
570 }
571 
572 
573 static int
574 var_compare(const void *a, const void *b)
575 {
576 	const char *const *sa, *const *sb;
577 
578 	sa = a;
579 	sb = b;
580 	/*
581 	 * This compares two var=value strings which creates a different
582 	 * order from what you would probably expect.  POSIX is somewhat
583 	 * ambiguous on what should be sorted exactly.
584 	 */
585 	return strcoll(*sa, *sb);
586 }
587 
588 
589 /*
590  * Command to list all variables which are set.  This is invoked from the
591  * set command when it is called without any options or operands.
592  */
593 
594 int
595 showvarscmd(int argc __unused, char **argv __unused)
596 {
597 	struct var **vpp;
598 	struct var *vp;
599 	const char *s;
600 	const char **vars;
601 	int i, n;
602 
603 	/*
604 	 * POSIX requires us to sort the variables.
605 	 */
606 	n = 0;
607 	for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) {
608 		for (vp = *vpp; vp; vp = vp->next) {
609 			if (!(vp->flags & VUNSET))
610 				n++;
611 		}
612 	}
613 
614 	INTOFF;
615 	vars = ckmalloc(n * sizeof(*vars));
616 	i = 0;
617 	for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) {
618 		for (vp = *vpp; vp; vp = vp->next) {
619 			if (!(vp->flags & VUNSET))
620 				vars[i++] = vp->text;
621 		}
622 	}
623 
624 	qsort(vars, n, sizeof(*vars), var_compare);
625 	for (i = 0; i < n; i++) {
626 		/*
627 		 * Skip improper variable names so the output remains usable as
628 		 * shell input.
629 		 */
630 		if (!isassignment(vars[i]))
631 			continue;
632 		s = strchr(vars[i], '=');
633 		s++;
634 		outbin(vars[i], s - vars[i], out1);
635 		out1qstr(s);
636 		out1c('\n');
637 	}
638 	ckfree(vars);
639 	INTON;
640 
641 	return 0;
642 }
643 
644 
645 
646 /*
647  * The export and readonly commands.
648  */
649 
650 int
651 exportcmd(int argc __unused, char **argv)
652 {
653 	struct var **vpp;
654 	struct var *vp;
655 	char **ap;
656 	char *name;
657 	char *p;
658 	char *cmdname;
659 	int ch, values;
660 	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
661 
662 	cmdname = argv[0];
663 	values = 0;
664 	while ((ch = nextopt("p")) != '\0') {
665 		switch (ch) {
666 		case 'p':
667 			values = 1;
668 			break;
669 		}
670 	}
671 
672 	if (values && *argptr != NULL)
673 		error("-p requires no arguments");
674 	if (*argptr != NULL) {
675 		for (ap = argptr; (name = *ap) != NULL; ap++) {
676 			if ((p = strchr(name, '=')) != NULL) {
677 				p++;
678 			} else {
679 				vp = find_var(name, NULL, NULL);
680 				if (vp != NULL) {
681 					vp->flags |= flag;
682 					if ((vp->flags & VEXPORT) && localevar(vp->text)) {
683 						change_env(vp->text, 1);
684 						(void) setlocale(LC_ALL, "");
685 						updatecharset();
686 					}
687 					continue;
688 				}
689 			}
690 			setvar(name, p, flag);
691 		}
692 	} else {
693 		for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
694 			for (vp = *vpp ; vp ; vp = vp->next) {
695 				if (vp->flags & flag) {
696 					if (values) {
697 						/*
698 						 * Skip improper variable names
699 						 * so the output remains usable
700 						 * as shell input.
701 						 */
702 						if (!isassignment(vp->text))
703 							continue;
704 						out1str(cmdname);
705 						out1c(' ');
706 					}
707 					if (values && !(vp->flags & VUNSET)) {
708 						outbin(vp->text,
709 						    vp->name_len + 1, out1);
710 						out1qstr(vp->text +
711 						    vp->name_len + 1);
712 					} else
713 						outbin(vp->text, vp->name_len,
714 						    out1);
715 					out1c('\n');
716 				}
717 			}
718 		}
719 	}
720 	return 0;
721 }
722 
723 
724 /*
725  * The "local" command.
726  */
727 
728 int
729 localcmd(int argc __unused, char **argv __unused)
730 {
731 	char *name;
732 
733 	nextopt("");
734 	if (! in_function())
735 		error("Not in a function");
736 	while ((name = *argptr++) != NULL) {
737 		mklocal(name);
738 	}
739 	return 0;
740 }
741 
742 
743 /*
744  * Make a variable a local variable.  When a variable is made local, it's
745  * value and flags are saved in a localvar structure.  The saved values
746  * will be restored when the shell function returns.  We handle the name
747  * "-" as a special case.
748  */
749 
750 void
751 mklocal(char *name)
752 {
753 	struct localvar *lvp;
754 	struct var **vpp;
755 	struct var *vp;
756 
757 	INTOFF;
758 	lvp = ckmalloc(sizeof (struct localvar));
759 	if (name[0] == '-' && name[1] == '\0') {
760 		lvp->text = ckmalloc(sizeof optval);
761 		memcpy(lvp->text, optval, sizeof optval);
762 		vp = NULL;
763 	} else {
764 		vp = find_var(name, &vpp, NULL);
765 		if (vp == NULL) {
766 			if (strchr(name, '='))
767 				setvareq(savestr(name), VSTRFIXED | VNOLOCAL);
768 			else
769 				setvar(name, NULL, VSTRFIXED | VNOLOCAL);
770 			vp = *vpp;	/* the new variable */
771 			lvp->text = NULL;
772 			lvp->flags = VUNSET;
773 		} else {
774 			lvp->text = vp->text;
775 			lvp->flags = vp->flags;
776 			vp->flags |= VSTRFIXED|VTEXTFIXED;
777 			if (name[vp->name_len] == '=')
778 				setvareq(savestr(name), VNOLOCAL);
779 		}
780 	}
781 	lvp->vp = vp;
782 	lvp->next = localvars;
783 	localvars = lvp;
784 	INTON;
785 }
786 
787 
788 /*
789  * Called after a function returns.
790  */
791 
792 void
793 poplocalvars(void)
794 {
795 	struct localvar *lvp;
796 	struct var *vp;
797 	int islocalevar;
798 
799 	INTOFF;
800 	while ((lvp = localvars) != NULL) {
801 		localvars = lvp->next;
802 		vp = lvp->vp;
803 		if (vp == NULL) {	/* $- saved */
804 			memcpy(optval, lvp->text, sizeof optval);
805 			ckfree(lvp->text);
806 			optschanged();
807 		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
808 			vp->flags &= ~VREADONLY;
809 			(void)unsetvar(vp->text);
810 		} else {
811 			islocalevar = (vp->flags | lvp->flags) & VEXPORT &&
812 			    localevar(lvp->text);
813 			if ((vp->flags & VTEXTFIXED) == 0)
814 				ckfree(vp->text);
815 			vp->flags = lvp->flags;
816 			vp->text = lvp->text;
817 			if (vp->func)
818 				(*vp->func)(vp->text + vp->name_len + 1);
819 			if (islocalevar) {
820 				change_env(vp->text, vp->flags & VEXPORT &&
821 				    (vp->flags & VUNSET) == 0);
822 				setlocale(LC_ALL, "");
823 				updatecharset();
824 			}
825 		}
826 		ckfree(lvp);
827 	}
828 	INTON;
829 }
830 
831 
832 int
833 setvarcmd(int argc, char **argv)
834 {
835 	if (argc <= 2)
836 		return unsetcmd(argc, argv);
837 	else if (argc == 3)
838 		setvar(argv[1], argv[2], 0);
839 	else
840 		error("too many arguments");
841 	return 0;
842 }
843 
844 
845 /*
846  * The unset builtin command.
847  */
848 
849 int
850 unsetcmd(int argc __unused, char **argv __unused)
851 {
852 	char **ap;
853 	int i;
854 	int flg_func = 0;
855 	int flg_var = 0;
856 	int ret = 0;
857 
858 	while ((i = nextopt("vf")) != '\0') {
859 		if (i == 'f')
860 			flg_func = 1;
861 		else
862 			flg_var = 1;
863 	}
864 	if (flg_func == 0 && flg_var == 0)
865 		flg_var = 1;
866 
867 	INTOFF;
868 	for (ap = argptr; *ap ; ap++) {
869 		if (flg_func)
870 			ret |= unsetfunc(*ap);
871 		if (flg_var)
872 			ret |= unsetvar(*ap);
873 	}
874 	INTON;
875 	return ret;
876 }
877 
878 
879 /*
880  * Unset the specified variable.
881  * Called with interrupts off.
882  */
883 
884 int
885 unsetvar(const char *s)
886 {
887 	struct var **vpp;
888 	struct var *vp;
889 
890 	vp = find_var(s, &vpp, NULL);
891 	if (vp == NULL)
892 		return (0);
893 	if (vp->flags & VREADONLY)
894 		return (1);
895 	if (vp->text[vp->name_len + 1] != '\0')
896 		setvar(s, "", 0);
897 	if ((vp->flags & VEXPORT) && localevar(vp->text)) {
898 		change_env(s, 0);
899 		setlocale(LC_ALL, "");
900 		updatecharset();
901 	}
902 	vp->flags &= ~VEXPORT;
903 	vp->flags |= VUNSET;
904 	if ((vp->flags & VSTRFIXED) == 0) {
905 		if ((vp->flags & VTEXTFIXED) == 0)
906 			ckfree(vp->text);
907 		*vpp = vp->next;
908 		ckfree(vp);
909 	}
910 	return (0);
911 }
912 
913 
914 
915 /*
916  * Returns true if the two strings specify the same variable.  The first
917  * variable name is terminated by '='; the second may be terminated by
918  * either '=' or '\0'.
919  */
920 
921 static int
922 varequal(const char *p, const char *q)
923 {
924 	while (*p == *q++) {
925 		if (*p++ == '=')
926 			return 1;
927 	}
928 	if (*p == '=' && *(q - 1) == '\0')
929 		return 1;
930 	return 0;
931 }
932 
933 /*
934  * Search for a variable.
935  * 'name' may be terminated by '=' or a NUL.
936  * vppp is set to the pointer to vp, or the list head if vp isn't found
937  * lenp is set to the number of characters in 'name'
938  */
939 
940 static struct var *
941 find_var(const char *name, struct var ***vppp, int *lenp)
942 {
943 	unsigned int hashval;
944 	int len;
945 	struct var *vp, **vpp;
946 	const char *p = name;
947 
948 	hashval = 0;
949 	while (*p && *p != '=')
950 		hashval = 2 * hashval + (unsigned char)*p++;
951 	len = p - name;
952 
953 	if (lenp)
954 		*lenp = len;
955 	vpp = &vartab[hashval % VTABSIZE];
956 	if (vppp)
957 		*vppp = vpp;
958 
959 	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
960 		if (vp->name_len != len)
961 			continue;
962 		if (memcmp(vp->text, name, len) != 0)
963 			continue;
964 		if (vppp)
965 			*vppp = vpp;
966 		return vp;
967 	}
968 	return NULL;
969 }
970