xref: /netbsd/bin/sh/var.c (revision bf9ec67e) 
1 /*	$NetBSD: var.c,v 1.28 2002/05/15 19:43:29 bjh21 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. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by the University of
21  *	California, Berkeley and its contributors.
22  * 4. Neither the name of the University nor the names of its contributors
23  *    may be used to endorse or promote products derived from this software
24  *    without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36  * SUCH DAMAGE.
37  */
38 
39 #include <sys/cdefs.h>
40 #ifndef lint
41 #if 0
42 static char sccsid[] = "@(#)var.c	8.3 (Berkeley) 5/4/95";
43 #else
44 __RCSID("$NetBSD: var.c,v 1.28 2002/05/15 19:43:29 bjh21 Exp $");
45 #endif
46 #endif /* not lint */
47 
48 #include <unistd.h>
49 #include <stdlib.h>
50 #include <paths.h>
51 
52 /*
53  * Shell variables.
54  */
55 
56 #include "shell.h"
57 #include "output.h"
58 #include "expand.h"
59 #include "nodes.h"	/* for other headers */
60 #include "eval.h"	/* defines cmdenviron */
61 #include "exec.h"
62 #include "syntax.h"
63 #include "options.h"
64 #include "mail.h"
65 #include "var.h"
66 #include "memalloc.h"
67 #include "error.h"
68 #include "mystring.h"
69 #include "parser.h"
70 #ifndef SMALL
71 #include "myhistedit.h"
72 #endif
73 
74 
75 #define VTABSIZE 39
76 
77 
78 struct varinit {
79 	struct var *var;
80 	int flags;
81 	const char *text;
82 	void (*func) __P((const char *));
83 };
84 
85 
86 #if ATTY
87 struct var vatty;
88 #endif
89 #ifndef SMALL
90 struct var vhistsize;
91 struct var vterm;
92 #endif
93 struct var vifs;
94 struct var vmail;
95 struct var vmpath;
96 struct var vpath;
97 struct var vps1;
98 struct var vps2;
99 struct var vvers;
100 struct var voptind;
101 
102 const struct varinit varinit[] = {
103 #if ATTY
104 	{ &vatty,	VSTRFIXED|VTEXTFIXED|VUNSET,	"ATTY=",
105 	  NULL },
106 #endif
107 #ifndef SMALL
108 	{ &vhistsize,	VSTRFIXED|VTEXTFIXED|VUNSET,	"HISTSIZE=",
109 	  sethistsize },
110 #endif
111 	{ &vifs,	VSTRFIXED|VTEXTFIXED,		"IFS= \t\n",
112 	  NULL },
113 	{ &vmail,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAIL=",
114 	  NULL },
115 	{ &vmpath,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAILPATH=",
116 	  NULL },
117 	{ &vpath,	VSTRFIXED|VTEXTFIXED,		"PATH=" _PATH_DEFPATH,
118 	  changepath },
119 	/*
120 	 * vps1 depends on uid
121 	 */
122 	{ &vps2,	VSTRFIXED|VTEXTFIXED,		"PS2=> ",
123 	  NULL },
124 #ifndef SMALL
125 	{ &vterm,	VSTRFIXED|VTEXTFIXED|VUNSET,	"TERM=",
126 	  setterm },
127 #endif
128 	{ &voptind,	VSTRFIXED|VTEXTFIXED,		"OPTIND=1",
129 	  getoptsreset },
130 	{ NULL,	0,				NULL,
131 	  NULL }
132 };
133 
134 struct var *vartab[VTABSIZE];
135 
136 STATIC struct var **hashvar __P((const char *));
137 STATIC int varequal __P((const char *, const char *));
138 
139 /*
140  * Initialize the varable symbol tables and import the environment
141  */
142 
143 #ifdef mkinit
144 INCLUDE "var.h"
145 MKINIT char **environ;
146 INIT {
147 	char **envp;
148 
149 	initvar();
150 	for (envp = environ ; *envp ; envp++) {
151 		if (strchr(*envp, '=')) {
152 			setvareq(*envp, VEXPORT|VTEXTFIXED);
153 		}
154 	}
155 }
156 #endif
157 
158 
159 /*
160  * This routine initializes the builtin variables.  It is called when the
161  * shell is initialized and again when a shell procedure is spawned.
162  */
163 
164 void
165 initvar() {
166 	const struct varinit *ip;
167 	struct var *vp;
168 	struct var **vpp;
169 
170 	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
171 		if ((vp->flags & VEXPORT) == 0) {
172 			vpp = hashvar(ip->text);
173 			vp->next = *vpp;
174 			*vpp = vp;
175 			vp->text = strdup(ip->text);
176 			vp->flags = ip->flags;
177 			vp->func = ip->func;
178 		}
179 	}
180 	/*
181 	 * PS1 depends on uid
182 	 */
183 	if ((vps1.flags & VEXPORT) == 0) {
184 		vpp = hashvar("PS1=");
185 		vps1.next = *vpp;
186 		*vpp = &vps1;
187 		vps1.text = strdup(geteuid() ? "PS1=$ " : "PS1=# ");
188 		vps1.flags = VSTRFIXED|VTEXTFIXED;
189 	}
190 }
191 
192 /*
193  * Safe version of setvar, returns 1 on success 0 on failure.
194  */
195 
196 int
197 setvarsafe(name, val, flags)
198 	const char *name, *val;
199 	int flags;
200 {
201 	struct jmploc jmploc;
202 	struct jmploc *volatile savehandler = handler;
203 	int err = 0;
204 #ifdef __GNUC__
205 	(void) &err;
206 #endif
207 
208 	if (setjmp(jmploc.loc))
209 		err = 1;
210 	else {
211 		handler = &jmploc;
212 		setvar(name, val, flags);
213 	}
214 	handler = savehandler;
215 	return err;
216 }
217 
218 /*
219  * Set the value of a variable.  The flags argument is ored with the
220  * flags of the variable.  If val is NULL, the variable is unset.
221  */
222 
223 void
224 setvar(name, val, flags)
225 	const char *name, *val;
226 	int flags;
227 {
228 	const char *p;
229 	const char *q;
230 	char *d;
231 	int len;
232 	int namelen;
233 	char *nameeq;
234 	int isbad;
235 
236 	isbad = 0;
237 	p = name;
238 	if (! is_name(*p))
239 		isbad = 1;
240 	p++;
241 	for (;;) {
242 		if (! is_in_name(*p)) {
243 			if (*p == '\0' || *p == '=')
244 				break;
245 			isbad = 1;
246 		}
247 		p++;
248 	}
249 	namelen = p - name;
250 	if (isbad)
251 		error("%.*s: bad variable name", namelen, name);
252 	len = namelen + 2;		/* 2 is space for '=' and '\0' */
253 	if (val == NULL) {
254 		flags |= VUNSET;
255 	} else {
256 		len += strlen(val);
257 	}
258 	d = nameeq = ckmalloc(len);
259 	q = name;
260 	while (--namelen >= 0)
261 		*d++ = *q++;
262 	*d++ = '=';
263 	*d = '\0';
264 	if (val)
265 		scopy(val, d);
266 	setvareq(nameeq, flags);
267 }
268 
269 
270 
271 /*
272  * Same as setvar except that the variable and value are passed in
273  * the first argument as name=value.  Since the first argument will
274  * be actually stored in the table, it should not be a string that
275  * will go away.
276  */
277 
278 void
279 setvareq(s, flags)
280 	char *s;
281 	int flags;
282 {
283 	struct var *vp, **vpp;
284 
285 	if (aflag)
286 		flags |= VEXPORT;
287 	vpp = hashvar(s);
288 	for (vp = *vpp ; vp ; vp = vp->next) {
289 		if (varequal(s, vp->text)) {
290 			if (vp->flags & VREADONLY) {
291 				size_t len = strchr(s, '=') - s;
292 				error("%.*s: is read only", len, s);
293 			}
294 			INTOFF;
295 
296 			if (vp->func && (flags & VNOFUNC) == 0)
297 				(*vp->func)(strchr(s, '=') + 1);
298 
299 			if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
300 				ckfree(vp->text);
301 
302 			vp->flags &= ~(VTEXTFIXED|VSTACK|VUNSET);
303 			vp->flags |= flags;
304 			vp->text = s;
305 
306 			/*
307 			 * We could roll this to a function, to handle it as
308 			 * a regular variable function callback, but why bother?
309 			 */
310 			if (vp == &vmpath || (vp == &vmail && ! mpathset()))
311 				chkmail(1);
312 			INTON;
313 			return;
314 		}
315 	}
316 	/* not found */
317 	vp = ckmalloc(sizeof (*vp));
318 	vp->flags = flags;
319 	vp->text = s;
320 	vp->next = *vpp;
321 	vp->func = NULL;
322 	*vpp = vp;
323 }
324 
325 
326 
327 /*
328  * Process a linked list of variable assignments.
329  */
330 
331 void
332 listsetvar(list)
333 	struct strlist *list;
334 	{
335 	struct strlist *lp;
336 
337 	INTOFF;
338 	for (lp = list ; lp ; lp = lp->next) {
339 		setvareq(savestr(lp->text), 0);
340 	}
341 	INTON;
342 }
343 
344 
345 
346 /*
347  * Find the value of a variable.  Returns NULL if not set.
348  */
349 
350 char *
351 lookupvar(name)
352 	const char *name;
353 	{
354 	struct var *v;
355 
356 	for (v = *hashvar(name) ; v ; v = v->next) {
357 		if (varequal(v->text, name)) {
358 			if (v->flags & VUNSET)
359 				return NULL;
360 			return strchr(v->text, '=') + 1;
361 		}
362 	}
363 	return NULL;
364 }
365 
366 
367 
368 /*
369  * Search the environment of a builtin command.  If the second argument
370  * is nonzero, return the value of a variable even if it hasn't been
371  * exported.
372  */
373 
374 char *
375 bltinlookup(name, doall)
376 	const char *name;
377 	int doall;
378 {
379 	struct strlist *sp;
380 	struct var *v;
381 
382 	for (sp = cmdenviron ; sp ; sp = sp->next) {
383 		if (varequal(sp->text, name))
384 			return strchr(sp->text, '=') + 1;
385 	}
386 	for (v = *hashvar(name) ; v ; v = v->next) {
387 		if (varequal(v->text, name)) {
388 			if ((v->flags & VUNSET)
389 			 || (!doall && (v->flags & VEXPORT) == 0))
390 				return NULL;
391 			return strchr(v->text, '=') + 1;
392 		}
393 	}
394 	return NULL;
395 }
396 
397 
398 
399 /*
400  * Generate a list of exported variables.  This routine is used to construct
401  * the third argument to execve when executing a program.
402  */
403 
404 char **
405 environment() {
406 	int nenv;
407 	struct var **vpp;
408 	struct var *vp;
409 	char **env;
410 	char **ep;
411 
412 	nenv = 0;
413 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
414 		for (vp = *vpp ; vp ; vp = vp->next)
415 			if (vp->flags & VEXPORT)
416 				nenv++;
417 	}
418 	ep = env = stalloc((nenv + 1) * sizeof *env);
419 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
420 		for (vp = *vpp ; vp ; vp = vp->next)
421 			if (vp->flags & VEXPORT)
422 				*ep++ = vp->text;
423 	}
424 	*ep = NULL;
425 	return env;
426 }
427 
428 
429 /*
430  * Called when a shell procedure is invoked to clear out nonexported
431  * variables.  It is also necessary to reallocate variables of with
432  * VSTACK set since these are currently allocated on the stack.
433  */
434 
435 #ifdef mkinit
436 void shprocvar __P((void));
437 
438 SHELLPROC {
439 	shprocvar();
440 }
441 #endif
442 
443 void
444 shprocvar() {
445 	struct var **vpp;
446 	struct var *vp, **prev;
447 
448 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
449 		for (prev = vpp ; (vp = *prev) != NULL ; ) {
450 			if ((vp->flags & VEXPORT) == 0) {
451 				*prev = vp->next;
452 				if ((vp->flags & VTEXTFIXED) == 0)
453 					ckfree(vp->text);
454 				if ((vp->flags & VSTRFIXED) == 0)
455 					ckfree(vp);
456 			} else {
457 				if (vp->flags & VSTACK) {
458 					vp->text = savestr(vp->text);
459 					vp->flags &=~ VSTACK;
460 				}
461 				prev = &vp->next;
462 			}
463 		}
464 	}
465 	initvar();
466 }
467 
468 
469 
470 /*
471  * Command to list all variables which are set.  Currently this command
472  * is invoked from the set command when the set command is called without
473  * any variables.
474  */
475 
476 int
477 showvarscmd(argc, argv)
478 	int argc;
479 	char **argv;
480 {
481 	struct var **vpp;
482 	struct var *vp;
483 
484 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
485 		for (vp = *vpp ; vp ; vp = vp->next) {
486 			if ((vp->flags & VUNSET) == 0)
487 				out1fmt("%s\n", vp->text);
488 		}
489 	}
490 	return 0;
491 }
492 
493 
494 
495 /*
496  * The export and readonly commands.
497  */
498 
499 int
500 exportcmd(argc, argv)
501 	int argc;
502 	char **argv;
503 {
504 	struct var **vpp;
505 	struct var *vp;
506 	char *name;
507 	const char *p;
508 	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
509 	int pflag;
510 
511 	listsetvar(cmdenviron);
512 	pflag = (nextopt("p") == 'p');
513 	if (argc > 1 && !pflag) {
514 		while ((name = *argptr++) != NULL) {
515 			if ((p = strchr(name, '=')) != NULL) {
516 				p++;
517 			} else {
518 				vpp = hashvar(name);
519 				for (vp = *vpp ; vp ; vp = vp->next) {
520 					if (varequal(vp->text, name)) {
521 						vp->flags |= flag;
522 						goto found;
523 					}
524 				}
525 			}
526 			setvar(name, p, flag);
527 found:;
528 		}
529 	} else {
530 		for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
531 			for (vp = *vpp ; vp ; vp = vp->next) {
532 				if ((vp->flags & flag) == 0)
533 					continue;
534 				if (pflag) {
535 					out1fmt("%s %s\n", argv[0], vp->text);
536 				} else {
537 					for (p = vp->text ; *p != '=' ; p++)
538 						out1c(*p);
539 					out1c('\n');
540 				}
541 			}
542 		}
543 	}
544 	return 0;
545 }
546 
547 
548 /*
549  * The "local" command.
550  */
551 
552 int
553 localcmd(argc, argv)
554 	int argc;
555 	char **argv;
556 {
557 	char *name;
558 
559 	if (! in_function())
560 		error("Not in a function");
561 	while ((name = *argptr++) != NULL) {
562 		mklocal(name);
563 	}
564 	return 0;
565 }
566 
567 
568 /*
569  * Make a variable a local variable.  When a variable is made local, it's
570  * value and flags are saved in a localvar structure.  The saved values
571  * will be restored when the shell function returns.  We handle the name
572  * "-" as a special case.
573  */
574 
575 void
576 mklocal(name)
577 	char *name;
578 	{
579 	struct localvar *lvp;
580 	struct var **vpp;
581 	struct var *vp;
582 
583 	INTOFF;
584 	lvp = ckmalloc(sizeof (struct localvar));
585 	if (name[0] == '-' && name[1] == '\0') {
586 		char *p;
587 		p = ckmalloc(sizeof optlist);
588 		lvp->text = memcpy(p, optlist, sizeof optlist);
589 		vp = NULL;
590 	} else {
591 		vpp = hashvar(name);
592 		for (vp = *vpp ; vp && ! varequal(vp->text, name) ; vp = vp->next);
593 		if (vp == NULL) {
594 			if (strchr(name, '='))
595 				setvareq(savestr(name), VSTRFIXED);
596 			else
597 				setvar(name, NULL, VSTRFIXED);
598 			vp = *vpp;	/* the new variable */
599 			lvp->text = NULL;
600 			lvp->flags = VUNSET;
601 		} else {
602 			lvp->text = vp->text;
603 			lvp->flags = vp->flags;
604 			vp->flags |= VSTRFIXED|VTEXTFIXED;
605 			if (strchr(name, '='))
606 				setvareq(savestr(name), 0);
607 		}
608 	}
609 	lvp->vp = vp;
610 	lvp->next = localvars;
611 	localvars = lvp;
612 	INTON;
613 }
614 
615 
616 /*
617  * Called after a function returns.
618  */
619 
620 void
621 poplocalvars() {
622 	struct localvar *lvp;
623 	struct var *vp;
624 
625 	while ((lvp = localvars) != NULL) {
626 		localvars = lvp->next;
627 		vp = lvp->vp;
628 		if (vp == NULL) {	/* $- saved */
629 			memcpy(optlist, lvp->text, sizeof optlist);
630 			ckfree(lvp->text);
631 		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
632 			(void)unsetvar(vp->text);
633 		} else {
634 			if ((vp->flags & VTEXTFIXED) == 0)
635 				ckfree(vp->text);
636 			vp->flags = lvp->flags;
637 			vp->text = lvp->text;
638 		}
639 		ckfree(lvp);
640 	}
641 }
642 
643 
644 int
645 setvarcmd(argc, argv)
646 	int argc;
647 	char **argv;
648 {
649 	if (argc <= 2)
650 		return unsetcmd(argc, argv);
651 	else if (argc == 3)
652 		setvar(argv[1], argv[2], 0);
653 	else
654 		error("List assignment not implemented");
655 	return 0;
656 }
657 
658 
659 /*
660  * The unset builtin command.  We unset the function before we unset the
661  * variable to allow a function to be unset when there is a readonly variable
662  * with the same name.
663  */
664 
665 int
666 unsetcmd(argc, argv)
667 	int argc;
668 	char **argv;
669 {
670 	char **ap;
671 	int i;
672 	int flg_func = 0;
673 	int flg_var = 0;
674 	int ret = 0;
675 
676 	while ((i = nextopt("vf")) != '\0') {
677 		if (i == 'f')
678 			flg_func = 1;
679 		else
680 			flg_var = 1;
681 	}
682 	if (flg_func == 0 && flg_var == 0)
683 		flg_var = 1;
684 
685 	for (ap = argptr; *ap ; ap++) {
686 		if (flg_func)
687 			ret |= unsetfunc(*ap);
688 		if (flg_var)
689 			ret |= unsetvar(*ap);
690 	}
691 	return ret;
692 }
693 
694 
695 /*
696  * Unset the specified variable.
697  */
698 
699 int
700 unsetvar(s)
701 	const char *s;
702 	{
703 	struct var **vpp;
704 	struct var *vp;
705 
706 	vpp = hashvar(s);
707 	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
708 		if (varequal(vp->text, s)) {
709 			if (vp->flags & VREADONLY)
710 				return (1);
711 			INTOFF;
712 			if (*(strchr(vp->text, '=') + 1) != '\0')
713 				setvar(s, nullstr, 0);
714 			vp->flags &= ~VEXPORT;
715 			vp->flags |= VUNSET;
716 			if ((vp->flags & VSTRFIXED) == 0) {
717 				if ((vp->flags & VTEXTFIXED) == 0)
718 					ckfree(vp->text);
719 				*vpp = vp->next;
720 				ckfree(vp);
721 			}
722 			INTON;
723 			return (0);
724 		}
725 	}
726 
727 	return (1);
728 }
729 
730 
731 
732 /*
733  * Find the appropriate entry in the hash table from the name.
734  */
735 
736 STATIC struct var **
737 hashvar(p)
738 	const char *p;
739 	{
740 	unsigned int hashval;
741 
742 	hashval = ((unsigned char) *p) << 4;
743 	while (*p && *p != '=')
744 		hashval += (unsigned char) *p++;
745 	return &vartab[hashval % VTABSIZE];
746 }
747 
748 
749 
750 /*
751  * Returns true if the two strings specify the same varable.  The first
752  * variable name is terminated by '='; the second may be terminated by
753  * either '=' or '\0'.
754  */
755 
756 STATIC int
757 varequal(p, q)
758 	const char *p, *q;
759 	{
760 	while (*p == *q++) {
761 		if (*p++ == '=')
762 			return 1;
763 	}
764 	if (*p == '=' && *(q - 1) == '\0')
765 		return 1;
766 	return 0;
767 }
768