var.c revision 17525 
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 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by the University of
19 *	California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 *
36 *	$Id: var.c,v 1.3 1995/05/30 00:07:24 rgrimes Exp $
37 */
38
39#ifndef lint
40static char sccsid[] = "@(#)var.c	8.1 (Berkeley) 5/31/93";
41#endif /* not lint */
42
43/*
44 * Shell variables.
45 */
46
47#include <locale.h>
48
49#include "shell.h"
50#include "output.h"
51#include "expand.h"
52#include "nodes.h"	/* for other headers */
53#include "eval.h"	/* defines cmdenviron */
54#include "exec.h"
55#include "syntax.h"
56#include "options.h"
57#include "mail.h"
58#include "var.h"
59#include "memalloc.h"
60#include "error.h"
61#include "mystring.h"
62
63
64#define VTABSIZE 39
65
66
67struct varinit {
68	struct var *var;
69	int flags;
70	char *text;
71};
72
73
74#if ATTY
75struct var vatty;
76#endif
77struct var vhistsize;
78struct var vifs;
79struct var vmail;
80struct var vmpath;
81struct var vpath;
82struct var vps1;
83struct var vps2;
84struct var vvers;
85#if ATTY
86struct var vterm;
87#endif
88
89const struct varinit varinit[] = {
90#if ATTY
91	{&vatty,	VSTRFIXED|VTEXTFIXED|VUNSET,	"ATTY="},
92#endif
93	{&vhistsize,	VSTRFIXED|VTEXTFIXED|VUNSET,	"HISTSIZE="},
94	{&vifs,	VSTRFIXED|VTEXTFIXED,		"IFS= \t\n"},
95	{&vmail,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAIL="},
96	{&vmpath,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAILPATH="},
97	{&vpath,	VSTRFIXED|VTEXTFIXED,		"PATH=:/bin:/usr/bin"},
98	/*
99	 * vps1 depends on uid
100	 */
101	{&vps2,	VSTRFIXED|VTEXTFIXED,		"PS2=> "},
102#if ATTY
103	{&vterm,	VSTRFIXED|VTEXTFIXED|VUNSET,	"TERM="},
104#endif
105	{NULL,	0,				NULL}
106};
107
108struct var *vartab[VTABSIZE];
109
110STATIC int unsetvar __P((char *));
111STATIC struct var **hashvar __P((char *));
112STATIC int varequal __P((char *, char *));
113STATIC int localevar __P((char *));
114
115/*
116 * Initialize the varable symbol tables and import the environment
117 */
118
119#ifdef mkinit
120INCLUDE "var.h"
121INIT {
122	char **envp;
123	extern char **environ;
124
125	initvar();
126	for (envp = environ ; *envp ; envp++) {
127		if (strchr(*envp, '=')) {
128			setvareq(*envp, VEXPORT|VTEXTFIXED);
129		}
130	}
131}
132#endif
133
134
135/*
136 * This routine initializes the builtin variables.  It is called when the
137 * shell is initialized and again when a shell procedure is spawned.
138 */
139
140void
141initvar() {
142	const struct varinit *ip;
143	struct var *vp;
144	struct var **vpp;
145
146	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
147		if ((vp->flags & VEXPORT) == 0) {
148			vpp = hashvar(ip->text);
149			vp->next = *vpp;
150			*vpp = vp;
151			vp->text = ip->text;
152			vp->flags = ip->flags;
153		}
154	}
155	/*
156	 * PS1 depends on uid
157	 */
158	if ((vps1.flags & VEXPORT) == 0) {
159		vpp = hashvar("PS1=");
160		vps1.next = *vpp;
161		*vpp = &vps1;
162		vps1.text = geteuid() ? "PS1=$ " : "PS1=# ";
163		vps1.flags = VSTRFIXED|VTEXTFIXED;
164	}
165}
166
167/*
168 * Set the value of a variable.  The flags argument is ored with the
169 * flags of the variable.  If val is NULL, the variable is unset.
170 */
171
172void
173setvar(name, val, flags)
174	char *name, *val;
175	{
176	char *p, *q;
177	int len;
178	int namelen;
179	char *nameeq;
180	int isbad;
181
182	isbad = 0;
183	p = name;
184	if (! is_name(*p))
185		isbad = 1;
186	p++;
187	for (;;) {
188		if (! is_in_name(*p)) {
189			if (*p == '\0' || *p == '=')
190				break;
191			isbad = 1;
192		}
193		p++;
194	}
195	namelen = p - name;
196	if (isbad)
197		error("%.*s: bad variable name", namelen, name);
198	len = namelen + 2;		/* 2 is space for '=' and '\0' */
199	if (val == NULL) {
200		flags |= VUNSET;
201	} else {
202		len += strlen(val);
203	}
204	p = nameeq = ckmalloc(len);
205	q = name;
206	while (--namelen >= 0)
207		*p++ = *q++;
208	*p++ = '=';
209	*p = '\0';
210	if (val)
211		scopy(val, p);
212	setvareq(nameeq, flags);
213}
214
215STATIC int
216localevar(s)
217	char *s;
218	{
219	static char *lnames[7] = {
220		"ALL", "COLLATE", "CTYPE", "MONETARY",
221		"NUMERIC", "TIME", NULL
222	};
223	char **ss;
224
225	if (*s != 'L')
226		return 0;
227	if (varequal(s + 1, "ANG"))
228		return 1;
229	if (strncmp(s + 1, "C_", 2) != 0)
230		return 0;
231	for (ss = lnames; *ss ; ss++)
232		if (varequal(s + 3, *ss))
233			return 1;
234	return 0;
235}
236
237/*
238 * Same as setvar except that the variable and value are passed in
239 * the first argument as name=value.  Since the first argument will
240 * be actually stored in the table, it should not be a string that
241 * will go away.
242 */
243
244void
245setvareq(s, flags)
246	char *s;
247	{
248	struct var *vp, **vpp;
249
250	vpp = hashvar(s);
251	for (vp = *vpp ; vp ; vp = vp->next) {
252		if (varequal(s, vp->text)) {
253			if (vp->flags & VREADONLY) {
254				int len = strchr(s, '=') - s;
255				error("%.*s: is read only", len, s);
256			}
257			INTOFF;
258			if (vp == &vpath)
259				changepath(s + 5);	/* 5 = strlen("PATH=") */
260			if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
261				ckfree(vp->text);
262			vp->flags &=~ (VTEXTFIXED|VSTACK|VUNSET);
263			vp->flags |= flags;
264			vp->text = s;
265			if (vp == &vmpath || (vp == &vmail && ! mpathset()))
266				chkmail(1);
267			if (vp == &vhistsize)
268				sethistsize();
269			if ((vp->flags & VEXPORT) && localevar(s)) {
270				putenv(s);
271				(void) setlocale(LC_ALL, "");
272			}
273			INTON;
274			return;
275		}
276	}
277	/* not found */
278	vp = ckmalloc(sizeof (*vp));
279	vp->flags = flags;
280	vp->text = s;
281	vp->next = *vpp;
282	INTOFF;
283	*vpp = vp;
284	if ((vp->flags & VEXPORT) && localevar(s)) {
285		putenv(s);
286		(void) setlocale(LC_ALL, "");
287	}
288	INTON;
289}
290
291
292
293/*
294 * Process a linked list of variable assignments.
295 */
296
297void
298listsetvar(list)
299	struct strlist *list;
300	{
301	struct strlist *lp;
302
303	INTOFF;
304	for (lp = list ; lp ; lp = lp->next) {
305		setvareq(savestr(lp->text), 0);
306	}
307	INTON;
308}
309
310
311
312/*
313 * Find the value of a variable.  Returns NULL if not set.
314 */
315
316char *
317lookupvar(name)
318	char *name;
319	{
320	struct var *v;
321
322	for (v = *hashvar(name) ; v ; v = v->next) {
323		if (varequal(v->text, name)) {
324			if (v->flags & VUNSET)
325				return NULL;
326			return strchr(v->text, '=') + 1;
327		}
328	}
329	return NULL;
330}
331
332
333
334/*
335 * Search the environment of a builtin command.  If the second argument
336 * is nonzero, return the value of a variable even if it hasn't been
337 * exported.
338 */
339
340char *
341bltinlookup(name, doall)
342	char *name;
343	{
344	struct strlist *sp;
345	struct var *v;
346
347	for (sp = cmdenviron ; sp ; sp = sp->next) {
348		if (varequal(sp->text, name))
349			return strchr(sp->text, '=') + 1;
350	}
351	for (v = *hashvar(name) ; v ; v = v->next) {
352		if (varequal(v->text, name)) {
353			if (v->flags & VUNSET
354			 || ! doall && (v->flags & VEXPORT) == 0)
355				return NULL;
356			return strchr(v->text, '=') + 1;
357		}
358	}
359	return NULL;
360}
361
362
363
364/*
365 * Generate a list of exported variables.  This routine is used to construct
366 * the third argument to execve when executing a program.
367 */
368
369char **
370environment() {
371	int nenv;
372	struct var **vpp;
373	struct var *vp;
374	char **env, **ep;
375
376	nenv = 0;
377	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
378		for (vp = *vpp ; vp ; vp = vp->next)
379			if (vp->flags & VEXPORT)
380				nenv++;
381	}
382	ep = env = stalloc((nenv + 1) * sizeof *env);
383	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
384		for (vp = *vpp ; vp ; vp = vp->next)
385			if (vp->flags & VEXPORT)
386				*ep++ = vp->text;
387	}
388	*ep = NULL;
389	return env;
390}
391
392
393/*
394 * Called when a shell procedure is invoked to clear out nonexported
395 * variables.  It is also necessary to reallocate variables of with
396 * VSTACK set since these are currently allocated on the stack.
397 */
398
399#ifdef mkinit
400MKINIT void shprocvar();
401
402SHELLPROC {
403	shprocvar();
404}
405#endif
406
407void
408shprocvar() {
409	struct var **vpp;
410	struct var *vp, **prev;
411
412	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
413		for (prev = vpp ; (vp = *prev) != NULL ; ) {
414			if ((vp->flags & VEXPORT) == 0) {
415				*prev = vp->next;
416				if ((vp->flags & VTEXTFIXED) == 0)
417					ckfree(vp->text);
418				if ((vp->flags & VSTRFIXED) == 0)
419					ckfree(vp);
420			} else {
421				if (vp->flags & VSTACK) {
422					vp->text = savestr(vp->text);
423					vp->flags &=~ VSTACK;
424				}
425				prev = &vp->next;
426			}
427		}
428	}
429	initvar();
430}
431
432
433
434/*
435 * Command to list all variables which are set.  Currently this command
436 * is invoked from the set command when the set command is called without
437 * any variables.
438 */
439
440int
441showvarscmd(argc, argv)  char **argv; {
442	struct var **vpp;
443	struct var *vp;
444
445	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
446		for (vp = *vpp ; vp ; vp = vp->next) {
447			if ((vp->flags & VUNSET) == 0)
448				out1fmt("%s\n", vp->text);
449		}
450	}
451	return 0;
452}
453
454
455
456/*
457 * The export and readonly commands.
458 */
459
460int
461exportcmd(argc, argv)  char **argv; {
462	struct var **vpp;
463	struct var *vp;
464	char *name;
465	char *p;
466	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
467
468	listsetvar(cmdenviron);
469	if (argc > 1) {
470		while ((name = *argptr++) != NULL) {
471			if ((p = strchr(name, '=')) != NULL) {
472				p++;
473			} else {
474				vpp = hashvar(name);
475				for (vp = *vpp ; vp ; vp = vp->next) {
476					if (varequal(vp->text, name)) {
477						vp->flags |= flag;
478						if ((vp->flags & VEXPORT) && localevar(vp->text)) {
479							putenv(vp->text);
480							(void) setlocale(LC_ALL, "");
481						}
482						goto found;
483					}
484				}
485			}
486			setvar(name, p, flag);
487found:;
488		}
489	} else {
490		for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
491			for (vp = *vpp ; vp ; vp = vp->next) {
492				if (vp->flags & flag) {
493					for (p = vp->text ; *p != '=' ; p++)
494						out1c(*p);
495					out1c('\n');
496				}
497			}
498		}
499	}
500	return 0;
501}
502
503
504/*
505 * The "local" command.
506 */
507
508localcmd(argc, argv)  char **argv; {
509	char *name;
510
511	if (! in_function())
512		error("Not in a function");
513	while ((name = *argptr++) != NULL) {
514		mklocal(name);
515	}
516	return 0;
517}
518
519
520/*
521 * Make a variable a local variable.  When a variable is made local, it's
522 * value and flags are saved in a localvar structure.  The saved values
523 * will be restored when the shell function returns.  We handle the name
524 * "-" as a special case.
525 */
526
527void
528mklocal(name)
529	char *name;
530	{
531	struct localvar *lvp;
532	struct var **vpp;
533	struct var *vp;
534
535	INTOFF;
536	lvp = ckmalloc(sizeof (struct localvar));
537	if (name[0] == '-' && name[1] == '\0') {
538		lvp->text = ckmalloc(sizeof optlist);
539		bcopy(optlist, lvp->text, sizeof optlist);
540		vp = NULL;
541	} else {
542		vpp = hashvar(name);
543		for (vp = *vpp ; vp && ! varequal(vp->text, name) ; vp = vp->next);
544		if (vp == NULL) {
545			if (strchr(name, '='))
546				setvareq(savestr(name), VSTRFIXED);
547			else
548				setvar(name, NULL, VSTRFIXED);
549			vp = *vpp;	/* the new variable */
550			lvp->text = NULL;
551			lvp->flags = VUNSET;
552		} else {
553			lvp->text = vp->text;
554			lvp->flags = vp->flags;
555			vp->flags |= VSTRFIXED|VTEXTFIXED;
556			if (strchr(name, '='))
557				setvareq(savestr(name), 0);
558		}
559	}
560	lvp->vp = vp;
561	lvp->next = localvars;
562	localvars = lvp;
563	INTON;
564}
565
566
567/*
568 * Called after a function returns.
569 */
570
571void
572poplocalvars() {
573	struct localvar *lvp;
574	struct var *vp;
575
576	while ((lvp = localvars) != NULL) {
577		localvars = lvp->next;
578		vp = lvp->vp;
579		if (vp == NULL) {	/* $- saved */
580			bcopy(lvp->text, optlist, sizeof optlist);
581			ckfree(lvp->text);
582		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
583			(void)unsetvar(vp->text);
584		} else {
585			if ((vp->flags & VTEXTFIXED) == 0)
586				ckfree(vp->text);
587			vp->flags = lvp->flags;
588			vp->text = lvp->text;
589		}
590		ckfree(lvp);
591	}
592}
593
594
595setvarcmd(argc, argv)  char **argv; {
596	if (argc <= 2)
597		return unsetcmd(argc, argv);
598	else if (argc == 3)
599		setvar(argv[1], argv[2], 0);
600	else
601		error("List assignment not implemented");
602	return 0;
603}
604
605
606/*
607 * The unset builtin command.  We unset the function before we unset the
608 * variable to allow a function to be unset when there is a readonly variable
609 * with the same name.
610 */
611
612unsetcmd(argc, argv)  char **argv; {
613	char **ap;
614	int i;
615	int flg_func = 0;
616	int flg_var = 0;
617	int ret = 0;
618
619	while ((i = nextopt("vf")) != '\0') {
620		if (i == 'f')
621			flg_func = 1;
622		else
623			flg_var = 1;
624	}
625	if (flg_func == 0 && flg_var == 0)
626		flg_var = 1;
627
628	for (ap = argptr; *ap ; ap++) {
629		if (flg_func)
630			ret |= unsetfunc(*ap);
631		if (flg_var)
632			ret |= unsetvar(*ap);
633	}
634	return ret;
635}
636
637
638/*
639 * Unset the specified variable.
640 */
641
642STATIC int
643unsetvar(s)
644	char *s;
645	{
646	struct var **vpp;
647	struct var *vp;
648
649	vpp = hashvar(s);
650	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
651		if (varequal(vp->text, s)) {
652			if (vp->flags & VREADONLY)
653				return (1);
654			INTOFF;
655			if (*(strchr(vp->text, '=') + 1) != '\0')
656				setvar(s, nullstr, 0);
657			if ((vp->flags & VEXPORT) && localevar(vp->text)) {
658				unsetenv(s);
659				setlocale(LC_ALL, "");
660			}
661			vp->flags &=~ VEXPORT;
662			vp->flags |= VUNSET;
663			if ((vp->flags & VSTRFIXED) == 0) {
664				if ((vp->flags & VTEXTFIXED) == 0)
665					ckfree(vp->text);
666				*vpp = vp->next;
667				ckfree(vp);
668			}
669			INTON;
670			return (0);
671		}
672	}
673
674	return (1);
675}
676
677
678
679/*
680 * Find the appropriate entry in the hash table from the name.
681 */
682
683STATIC struct var **
684hashvar(p)
685	register char *p;
686	{
687	unsigned int hashval;
688
689	hashval = ((unsigned char)*p) << 4;
690	while (*p && *p != '=')
691		hashval += (unsigned char)*p++;
692	return &vartab[hashval % VTABSIZE];
693}
694
695
696
697/*
698 * Returns true if the two strings specify the same varable.  The first
699 * variable name is terminated by '='; the second may be terminated by
700 * either '=' or '\0'.
701 */
702
703STATIC int
704varequal(p, q)
705	register char *p, *q;
706	{
707	while (*p == *q++) {
708		if (*p++ == '=')
709			return 1;
710	}
711	if (*p == '=' && *(q - 1) == '\0')
712		return 1;
713	return 0;
714}
715