xref: /freebsd/bin/sh/var.c (revision 3df058ffaf72b8715c9a5a6a4cbaf1eac1910e43) 
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 struct localvar *localvars;
98 int forcelocal;
99 
100 static const struct varinit varinit[] = {
101 #ifndef NO_HISTORY
102 	{ &vhistsize,	VUNSET,				"HISTSIZE=",
103 	  sethistsize },
104 #endif
105 	{ &vifs,	0,				"IFS= \t\n",
106 	  NULL },
107 	{ &vmail,	VUNSET,				"MAIL=",
108 	  NULL },
109 	{ &vmpath,	VUNSET,				"MAILPATH=",
110 	  NULL },
111 	{ &vpath,	0,				"PATH=" _PATH_DEFPATH,
112 	  changepath },
113 	/*
114 	 * vps1 depends on uid
115 	 */
116 	{ &vps2,	0,				"PS2=> ",
117 	  NULL },
118 	{ &vps4,	0,				"PS4=+ ",
119 	  NULL },
120 #ifndef NO_HISTORY
121 	{ &vterm,	VUNSET,				"TERM=",
122 	  setterm },
123 #endif
124 	{ &voptind,	0,				"OPTIND=1",
125 	  getoptsreset },
126 	{ &vdisvfork,	VUNSET,				"SH_DISABLE_VFORK=",
127 	  NULL },
128 	{ NULL,	0,				NULL,
129 	  NULL }
130 };
131 
132 static struct var *vartab[VTABSIZE];
133 
134 static const char *const locale_names[7] = {
135 	"LC_COLLATE", "LC_CTYPE", "LC_MONETARY",
136 	"LC_NUMERIC", "LC_TIME", "LC_MESSAGES", NULL
137 };
138 static const int locale_categories[7] = {
139 	LC_COLLATE, LC_CTYPE, LC_MONETARY, LC_NUMERIC, LC_TIME, LC_MESSAGES, 0
140 };
141 
142 static int varequal(const char *, const char *);
143 static struct var *find_var(const char *, struct var ***, int *);
144 static int localevar(const char *);
145 static void setvareq_const(const char *s, int flags);
146 
147 extern char **environ;
148 
149 /*
150  * This routine initializes the builtin variables and imports the environment.
151  * It is called when the shell is initialized.
152  */
153 
154 void
155 initvar(void)
156 {
157 	char ppid[20];
158 	const struct varinit *ip;
159 	struct var *vp;
160 	struct var **vpp;
161 	char **envp;
162 
163 	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
164 		if (find_var(ip->text, &vpp, &vp->name_len) != NULL)
165 			continue;
166 		vp->next = *vpp;
167 		*vpp = vp;
168 		vp->text = __DECONST(char *, ip->text);
169 		vp->flags = ip->flags | VSTRFIXED | VTEXTFIXED;
170 		vp->func = ip->func;
171 	}
172 	/*
173 	 * PS1 depends on uid
174 	 */
175 	if (find_var("PS1", &vpp, &vps1.name_len) == NULL) {
176 		vps1.next = *vpp;
177 		*vpp = &vps1;
178 		vps1.text = __DECONST(char *, geteuid() ? "PS1=$ " : "PS1=# ");
179 		vps1.flags = VSTRFIXED|VTEXTFIXED;
180 	}
181 	fmtstr(ppid, sizeof(ppid), "%d", (int)getppid());
182 	setvarsafe("PPID", ppid, 0);
183 	for (envp = environ ; *envp ; envp++) {
184 		if (strchr(*envp, '=')) {
185 			setvareq(*envp, VEXPORT|VTEXTFIXED);
186 		}
187 	}
188 	setvareq_const("OPTIND=1", 0);
189 }
190 
191 /*
192  * Safe version of setvar, returns 1 on success 0 on failure.
193  */
194 
195 int
196 setvarsafe(const char *name, const char *val, int flags)
197 {
198 	struct jmploc jmploc;
199 	struct jmploc *const savehandler = handler;
200 	int err = 0;
201 	int inton;
202 
203 	inton = is_int_on();
204 	if (setjmp(jmploc.loc))
205 		err = 1;
206 	else {
207 		handler = &jmploc;
208 		setvar(name, val, flags);
209 	}
210 	handler = savehandler;
211 	SETINTON(inton);
212 	return err;
213 }
214 
215 /*
216  * Set the value of a variable.  The flags argument is stored with the
217  * flags of the variable.  If val is NULL, the variable is unset.
218  */
219 
220 void
221 setvar(const char *name, const char *val, int flags)
222 {
223 	const char *p;
224 	size_t len;
225 	size_t namelen;
226 	size_t vallen;
227 	char *nameeq;
228 	int isbad;
229 
230 	isbad = 0;
231 	p = name;
232 	if (! is_name(*p))
233 		isbad = 1;
234 	p++;
235 	for (;;) {
236 		if (! is_in_name(*p)) {
237 			if (*p == '\0' || *p == '=')
238 				break;
239 			isbad = 1;
240 		}
241 		p++;
242 	}
243 	namelen = p - name;
244 	if (isbad)
245 		error("%.*s: bad variable name", (int)namelen, name);
246 	len = namelen + 2;		/* 2 is space for '=' and '\0' */
247 	if (val == NULL) {
248 		flags |= VUNSET;
249 		vallen = 0;
250 	} else {
251 		vallen = strlen(val);
252 		len += vallen;
253 	}
254 	INTOFF;
255 	nameeq = ckmalloc(len);
256 	memcpy(nameeq, name, namelen);
257 	nameeq[namelen] = '=';
258 	if (val)
259 		memcpy(nameeq + namelen + 1, val, vallen + 1);
260 	else
261 		nameeq[namelen + 1] = '\0';
262 	setvareq(nameeq, flags);
263 	INTON;
264 }
265 
266 static int
267 localevar(const char *s)
268 {
269 	const char *const *ss;
270 
271 	if (*s != 'L')
272 		return 0;
273 	if (varequal(s + 1, "ANG"))
274 		return 1;
275 	if (strncmp(s + 1, "C_", 2) != 0)
276 		return 0;
277 	if (varequal(s + 3, "ALL"))
278 		return 1;
279 	for (ss = locale_names; *ss ; ss++)
280 		if (varequal(s + 3, *ss + 3))
281 			return 1;
282 	return 0;
283 }
284 
285 
286 /*
287  * Sets/unsets an environment variable from a pointer that may actually be a
288  * pointer into environ where the string should not be manipulated.
289  */
290 static void
291 change_env(const char *s, int set)
292 {
293 	char *eqp;
294 	char *ss;
295 
296 	INTOFF;
297 	ss = savestr(s);
298 	if ((eqp = strchr(ss, '=')) != NULL)
299 		*eqp = '\0';
300 	if (set && eqp != NULL)
301 		(void) setenv(ss, eqp + 1, 1);
302 	else
303 		(void) unsetenv(ss);
304 	ckfree(ss);
305 	INTON;
306 
307 	return;
308 }
309 
310 
311 /*
312  * Same as setvar except that the variable and value are passed in
313  * the first argument as name=value.  Since the first argument will
314  * be actually stored in the table, it should not be a string that
315  * will go away.
316  */
317 
318 void
319 setvareq(char *s, int flags)
320 {
321 	struct var *vp, **vpp;
322 	int nlen;
323 
324 	if (aflag)
325 		flags |= VEXPORT;
326 	if (forcelocal && !(flags & (VNOSET | VNOLOCAL)))
327 		mklocal(s);
328 	vp = find_var(s, &vpp, &nlen);
329 	if (vp != NULL) {
330 		if (vp->flags & VREADONLY) {
331 			if ((flags & (VTEXTFIXED|VSTACK)) == 0)
332 				ckfree(s);
333 			error("%.*s: is read only", vp->name_len, s);
334 		}
335 		if (flags & VNOSET) {
336 			if ((flags & (VTEXTFIXED|VSTACK)) == 0)
337 				ckfree(s);
338 			return;
339 		}
340 		INTOFF;
341 
342 		if (vp->func && (flags & VNOFUNC) == 0)
343 			(*vp->func)(s + vp->name_len + 1);
344 
345 		if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
346 			ckfree(vp->text);
347 
348 		vp->flags &= ~(VTEXTFIXED|VSTACK|VUNSET);
349 		vp->flags |= flags;
350 		vp->text = s;
351 
352 		/*
353 		 * We could roll this to a function, to handle it as
354 		 * a regular variable function callback, but why bother?
355 		 *
356 		 * Note: this assumes iflag is not set to 1 initially.
357 		 * As part of initvar(), this is called before arguments
358 		 * are looked at.
359 		 */
360 		if ((vp == &vmpath || (vp == &vmail && ! mpathset())) &&
361 		    iflag == 1)
362 			chkmail(1);
363 		if ((vp->flags & VEXPORT) && localevar(s)) {
364 			change_env(s, 1);
365 			(void) setlocale(LC_ALL, "");
366 			updatecharset();
367 		}
368 		INTON;
369 		return;
370 	}
371 	/* not found */
372 	if (flags & VNOSET) {
373 		if ((flags & (VTEXTFIXED|VSTACK)) == 0)
374 			ckfree(s);
375 		return;
376 	}
377 	INTOFF;
378 	vp = ckmalloc(sizeof (*vp));
379 	vp->flags = flags;
380 	vp->text = s;
381 	vp->name_len = nlen;
382 	vp->next = *vpp;
383 	vp->func = NULL;
384 	*vpp = vp;
385 	if ((vp->flags & VEXPORT) && localevar(s)) {
386 		change_env(s, 1);
387 		(void) setlocale(LC_ALL, "");
388 		updatecharset();
389 	}
390 	INTON;
391 }
392 
393 
394 static void
395 setvareq_const(const char *s, int flags)
396 {
397 	setvareq(__DECONST(char *, s), flags | VTEXTFIXED);
398 }
399 
400 
401 /*
402  * Process a linked list of variable assignments.
403  */
404 
405 void
406 listsetvar(struct strlist *list, int flags)
407 {
408 	struct strlist *lp;
409 
410 	INTOFF;
411 	for (lp = list ; lp ; lp = lp->next) {
412 		setvareq(savestr(lp->text), flags);
413 	}
414 	INTON;
415 }
416 
417 
418 
419 /*
420  * Find the value of a variable.  Returns NULL if not set.
421  */
422 
423 char *
424 lookupvar(const char *name)
425 {
426 	struct var *v;
427 
428 	v = find_var(name, NULL, NULL);
429 	if (v == NULL || v->flags & VUNSET)
430 		return NULL;
431 	return v->text + v->name_len + 1;
432 }
433 
434 
435 
436 /*
437  * Search the environment of a builtin command.  If the second argument
438  * is nonzero, return the value of a variable even if it hasn't been
439  * exported.
440  */
441 
442 char *
443 bltinlookup(const char *name, int doall)
444 {
445 	struct strlist *sp;
446 	struct var *v;
447 	char *result;
448 
449 	result = NULL;
450 	for (sp = cmdenviron ; sp ; sp = sp->next) {
451 		if (varequal(sp->text, name))
452 			result = strchr(sp->text, '=') + 1;
453 	}
454 	if (result != NULL)
455 		return result;
456 
457 	v = find_var(name, NULL, NULL);
458 	if (v == NULL || v->flags & VUNSET ||
459 	    (!doall && (v->flags & VEXPORT) == 0))
460 		return NULL;
461 	return v->text + v->name_len + 1;
462 }
463 
464 
465 /*
466  * Set up locale for a builtin (LANG/LC_* assignments).
467  */
468 void
469 bltinsetlocale(void)
470 {
471 	struct strlist *lp;
472 	int act = 0;
473 	char *loc, *locdef;
474 	int i;
475 
476 	for (lp = cmdenviron ; lp ; lp = lp->next) {
477 		if (localevar(lp->text)) {
478 			act = 1;
479 			break;
480 		}
481 	}
482 	if (!act)
483 		return;
484 	loc = bltinlookup("LC_ALL", 0);
485 	INTOFF;
486 	if (loc != NULL) {
487 		setlocale(LC_ALL, loc);
488 		INTON;
489 		updatecharset();
490 		return;
491 	}
492 	locdef = bltinlookup("LANG", 0);
493 	for (i = 0; locale_names[i] != NULL; i++) {
494 		loc = bltinlookup(locale_names[i], 0);
495 		if (loc == NULL)
496 			loc = locdef;
497 		if (loc != NULL)
498 			setlocale(locale_categories[i], loc);
499 	}
500 	INTON;
501 	updatecharset();
502 }
503 
504 /*
505  * Undo the effect of bltinlocaleset().
506  */
507 void
508 bltinunsetlocale(void)
509 {
510 	struct strlist *lp;
511 
512 	INTOFF;
513 	for (lp = cmdenviron ; lp ; lp = lp->next) {
514 		if (localevar(lp->text)) {
515 			setlocale(LC_ALL, "");
516 			updatecharset();
517 			return;
518 		}
519 	}
520 	INTON;
521 }
522 
523 /*
524  * Update the localeisutf8 flag.
525  */
526 void
527 updatecharset(void)
528 {
529 	char *charset;
530 
531 	charset = nl_langinfo(CODESET);
532 	localeisutf8 = !strcmp(charset, "UTF-8");
533 }
534 
535 void
536 initcharset(void)
537 {
538 	updatecharset();
539 	initial_localeisutf8 = localeisutf8;
540 }
541 
542 /*
543  * Generate a list of exported variables.  This routine is used to construct
544  * the third argument to execve when executing a program.
545  */
546 
547 char **
548 environment(void)
549 {
550 	int nenv;
551 	struct var **vpp;
552 	struct var *vp;
553 	char **env, **ep;
554 
555 	nenv = 0;
556 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
557 		for (vp = *vpp ; vp ; vp = vp->next)
558 			if (vp->flags & VEXPORT)
559 				nenv++;
560 	}
561 	ep = env = stalloc((nenv + 1) * sizeof *env);
562 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
563 		for (vp = *vpp ; vp ; vp = vp->next)
564 			if (vp->flags & VEXPORT)
565 				*ep++ = vp->text;
566 	}
567 	*ep = NULL;
568 	return env;
569 }
570 
571 
572 static int
573 var_compare(const void *a, const void *b)
574 {
575 	const char *const *sa, *const *sb;
576 
577 	sa = a;
578 	sb = b;
579 	/*
580 	 * This compares two var=value strings which creates a different
581 	 * order from what you would probably expect.  POSIX is somewhat
582 	 * ambiguous on what should be sorted exactly.
583 	 */
584 	return strcoll(*sa, *sb);
585 }
586 
587 
588 /*
589  * Command to list all variables which are set.  This is invoked from the
590  * set command when it is called without any options or operands.
591  */
592 
593 int
594 showvarscmd(int argc __unused, char **argv __unused)
595 {
596 	struct var **vpp;
597 	struct var *vp;
598 	const char *s;
599 	const char **vars;
600 	int i, n;
601 
602 	/*
603 	 * POSIX requires us to sort the variables.
604 	 */
605 	n = 0;
606 	for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) {
607 		for (vp = *vpp; vp; vp = vp->next) {
608 			if (!(vp->flags & VUNSET))
609 				n++;
610 		}
611 	}
612 
613 	INTOFF;
614 	vars = ckmalloc(n * sizeof(*vars));
615 	i = 0;
616 	for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) {
617 		for (vp = *vpp; vp; vp = vp->next) {
618 			if (!(vp->flags & VUNSET))
619 				vars[i++] = vp->text;
620 		}
621 	}
622 
623 	qsort(vars, n, sizeof(*vars), var_compare);
624 	for (i = 0; i < n; i++) {
625 		/*
626 		 * Skip improper variable names so the output remains usable as
627 		 * shell input.
628 		 */
629 		if (!isassignment(vars[i]))
630 			continue;
631 		s = strchr(vars[i], '=');
632 		s++;
633 		outbin(vars[i], s - vars[i], out1);
634 		out1qstr(s);
635 		out1c('\n');
636 	}
637 	ckfree(vars);
638 	INTON;
639 
640 	return 0;
641 }
642 
643 
644 
645 /*
646  * The export and readonly commands.
647  */
648 
649 int
650 exportcmd(int argc __unused, char **argv)
651 {
652 	struct var **vpp;
653 	struct var *vp;
654 	char **ap;
655 	char *name;
656 	char *p;
657 	char *cmdname;
658 	int ch, values;
659 	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
660 
661 	cmdname = argv[0];
662 	values = 0;
663 	while ((ch = nextopt("p")) != '\0') {
664 		switch (ch) {
665 		case 'p':
666 			values = 1;
667 			break;
668 		}
669 	}
670 
671 	if (values && *argptr != NULL)
672 		error("-p requires no arguments");
673 	if (*argptr != NULL) {
674 		for (ap = argptr; (name = *ap) != NULL; ap++) {
675 			if ((p = strchr(name, '=')) != NULL) {
676 				p++;
677 			} else {
678 				vp = find_var(name, NULL, NULL);
679 				if (vp != NULL) {
680 					vp->flags |= flag;
681 					if ((vp->flags & VEXPORT) && localevar(vp->text)) {
682 						change_env(vp->text, 1);
683 						(void) setlocale(LC_ALL, "");
684 						updatecharset();
685 					}
686 					continue;
687 				}
688 			}
689 			setvar(name, p, flag);
690 		}
691 	} else {
692 		for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
693 			for (vp = *vpp ; vp ; vp = vp->next) {
694 				if (vp->flags & flag) {
695 					if (values) {
696 						/*
697 						 * Skip improper variable names
698 						 * so the output remains usable
699 						 * as shell input.
700 						 */
701 						if (!isassignment(vp->text))
702 							continue;
703 						out1str(cmdname);
704 						out1c(' ');
705 					}
706 					if (values && !(vp->flags & VUNSET)) {
707 						outbin(vp->text,
708 						    vp->name_len + 1, out1);
709 						out1qstr(vp->text +
710 						    vp->name_len + 1);
711 					} else
712 						outbin(vp->text, vp->name_len,
713 						    out1);
714 					out1c('\n');
715 				}
716 			}
717 		}
718 	}
719 	return 0;
720 }
721 
722 
723 /*
724  * The "local" command.
725  */
726 
727 int
728 localcmd(int argc __unused, char **argv __unused)
729 {
730 	char *name;
731 
732 	nextopt("");
733 	if (! in_function())
734 		error("Not in a function");
735 	while ((name = *argptr++) != NULL) {
736 		mklocal(name);
737 	}
738 	return 0;
739 }
740 
741 
742 /*
743  * Make a variable a local variable.  When a variable is made local, it's
744  * value and flags are saved in a localvar structure.  The saved values
745  * will be restored when the shell function returns.  We handle the name
746  * "-" as a special case.
747  */
748 
749 void
750 mklocal(char *name)
751 {
752 	struct localvar *lvp;
753 	struct var **vpp;
754 	struct var *vp;
755 
756 	INTOFF;
757 	lvp = ckmalloc(sizeof (struct localvar));
758 	if (name[0] == '-' && name[1] == '\0') {
759 		lvp->text = ckmalloc(sizeof optlist);
760 		memcpy(lvp->text, optlist, sizeof optlist);
761 		vp = NULL;
762 	} else {
763 		vp = find_var(name, &vpp, NULL);
764 		if (vp == NULL) {
765 			if (strchr(name, '='))
766 				setvareq(savestr(name), VSTRFIXED | VNOLOCAL);
767 			else
768 				setvar(name, NULL, VSTRFIXED | VNOLOCAL);
769 			vp = *vpp;	/* the new variable */
770 			lvp->text = NULL;
771 			lvp->flags = VUNSET;
772 		} else {
773 			lvp->text = vp->text;
774 			lvp->flags = vp->flags;
775 			vp->flags |= VSTRFIXED|VTEXTFIXED;
776 			if (name[vp->name_len] == '=')
777 				setvareq(savestr(name), VNOLOCAL);
778 		}
779 	}
780 	lvp->vp = vp;
781 	lvp->next = localvars;
782 	localvars = lvp;
783 	INTON;
784 }
785 
786 
787 /*
788  * Called after a function returns.
789  */
790 
791 void
792 poplocalvars(void)
793 {
794 	struct localvar *lvp;
795 	struct var *vp;
796 
797 	INTOFF;
798 	while ((lvp = localvars) != NULL) {
799 		localvars = lvp->next;
800 		vp = lvp->vp;
801 		if (vp == NULL) {	/* $- saved */
802 			memcpy(optlist, lvp->text, sizeof optlist);
803 			ckfree(lvp->text);
804 			optschanged();
805 		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
806 			(void)unsetvar(vp->text);
807 		} else {
808 			if ((vp->flags & VTEXTFIXED) == 0)
809 				ckfree(vp->text);
810 			vp->flags = lvp->flags;
811 			vp->text = lvp->text;
812 		}
813 		ckfree(lvp);
814 	}
815 	INTON;
816 }
817 
818 
819 int
820 setvarcmd(int argc, char **argv)
821 {
822 	if (argc <= 2)
823 		return unsetcmd(argc, argv);
824 	else if (argc == 3)
825 		setvar(argv[1], argv[2], 0);
826 	else
827 		error("too many arguments");
828 	return 0;
829 }
830 
831 
832 /*
833  * The unset builtin command.
834  */
835 
836 int
837 unsetcmd(int argc __unused, char **argv __unused)
838 {
839 	char **ap;
840 	int i;
841 	int flg_func = 0;
842 	int flg_var = 0;
843 	int ret = 0;
844 
845 	while ((i = nextopt("vf")) != '\0') {
846 		if (i == 'f')
847 			flg_func = 1;
848 		else
849 			flg_var = 1;
850 	}
851 	if (flg_func == 0 && flg_var == 0)
852 		flg_var = 1;
853 
854 	INTOFF;
855 	for (ap = argptr; *ap ; ap++) {
856 		if (flg_func)
857 			ret |= unsetfunc(*ap);
858 		if (flg_var)
859 			ret |= unsetvar(*ap);
860 	}
861 	INTON;
862 	return ret;
863 }
864 
865 
866 /*
867  * Unset the specified variable.
868  * Called with interrupts off.
869  */
870 
871 int
872 unsetvar(const char *s)
873 {
874 	struct var **vpp;
875 	struct var *vp;
876 
877 	vp = find_var(s, &vpp, NULL);
878 	if (vp == NULL)
879 		return (0);
880 	if (vp->flags & VREADONLY)
881 		return (1);
882 	if (vp->text[vp->name_len + 1] != '\0')
883 		setvar(s, "", 0);
884 	if ((vp->flags & VEXPORT) && localevar(vp->text)) {
885 		change_env(s, 0);
886 		setlocale(LC_ALL, "");
887 		updatecharset();
888 	}
889 	vp->flags &= ~VEXPORT;
890 	vp->flags |= VUNSET;
891 	if ((vp->flags & VSTRFIXED) == 0) {
892 		if ((vp->flags & VTEXTFIXED) == 0)
893 			ckfree(vp->text);
894 		*vpp = vp->next;
895 		ckfree(vp);
896 	}
897 	return (0);
898 }
899 
900 
901 
902 /*
903  * Returns true if the two strings specify the same variable.  The first
904  * variable name is terminated by '='; the second may be terminated by
905  * either '=' or '\0'.
906  */
907 
908 static int
909 varequal(const char *p, const char *q)
910 {
911 	while (*p == *q++) {
912 		if (*p++ == '=')
913 			return 1;
914 	}
915 	if (*p == '=' && *(q - 1) == '\0')
916 		return 1;
917 	return 0;
918 }
919 
920 /*
921  * Search for a variable.
922  * 'name' may be terminated by '=' or a NUL.
923  * vppp is set to the pointer to vp, or the list head if vp isn't found
924  * lenp is set to the number of characters in 'name'
925  */
926 
927 static struct var *
928 find_var(const char *name, struct var ***vppp, int *lenp)
929 {
930 	unsigned int hashval;
931 	int len;
932 	struct var *vp, **vpp;
933 	const char *p = name;
934 
935 	hashval = 0;
936 	while (*p && *p != '=')
937 		hashval = 2 * hashval + (unsigned char)*p++;
938 	len = p - name;
939 
940 	if (lenp)
941 		*lenp = len;
942 	vpp = &vartab[hashval % VTABSIZE];
943 	if (vppp)
944 		*vppp = vpp;
945 
946 	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
947 		if (vp->name_len != len)
948 			continue;
949 		if (memcmp(vp->text, name, len) != 0)
950 			continue;
951 		if (vppp)
952 			*vppp = vpp;
953 		return vp;
954 	}
955 	return NULL;
956 }
957