var.c revision 1557 
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
37#ifndef lint
38static char sccsid[] = "@(#)var.c	8.1 (Berkeley) 5/31/93";
39#endif /* not lint */
40
41/*
42 * Shell variables.
43 */
44
45#include "shell.h"
46#include "output.h"
47#include "expand.h"
48#include "nodes.h"	/* for other headers */
49#include "eval.h"	/* defines cmdenviron */
50#include "exec.h"
51#include "syntax.h"
52#include "options.h"
53#include "mail.h"
54#include "var.h"
55#include "memalloc.h"
56#include "error.h"
57#include "mystring.h"
58
59
60#define VTABSIZE 39
61
62
63struct varinit {
64	struct var *var;
65	int flags;
66	char *text;
67};
68
69
70#if ATTY
71struct var vatty;
72#endif
73struct var vhistsize;
74struct var vifs;
75struct var vmail;
76struct var vmpath;
77struct var vpath;
78struct var vps1;
79struct var vps2;
80struct var vvers;
81#if ATTY
82struct var vterm;
83#endif
84
85const struct varinit varinit[] = {
86#if ATTY
87	{&vatty,	VSTRFIXED|VTEXTFIXED|VUNSET,	"ATTY="},
88#endif
89	{&vhistsize,	VSTRFIXED|VTEXTFIXED|VUNSET,	"HISTSIZE="},
90	{&vifs,	VSTRFIXED|VTEXTFIXED,		"IFS= \t\n"},
91	{&vmail,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAIL="},
92	{&vmpath,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAILPATH="},
93	{&vpath,	VSTRFIXED|VTEXTFIXED,		"PATH=:/bin:/usr/bin"},
94	/*
95	 * vps1 depends on uid
96	 */
97	{&vps2,	VSTRFIXED|VTEXTFIXED,		"PS2=> "},
98#if ATTY
99	{&vterm,	VSTRFIXED|VTEXTFIXED|VUNSET,	"TERM="},
100#endif
101	{NULL,	0,				NULL}
102};
103
104struct var *vartab[VTABSIZE];
105
106STATIC int unsetvar __P((char *));
107STATIC struct var **hashvar __P((char *));
108STATIC int varequal __P((char *, char *));
109
110/*
111 * Initialize the varable symbol tables and import the environment
112 */
113
114#ifdef mkinit
115INCLUDE "var.h"
116INIT {
117	char **envp;
118	extern char **environ;
119
120	initvar();
121	for (envp = environ ; *envp ; envp++) {
122		if (strchr(*envp, '=')) {
123			setvareq(*envp, VEXPORT|VTEXTFIXED);
124		}
125	}
126}
127#endif
128
129
130/*
131 * This routine initializes the builtin variables.  It is called when the
132 * shell is initialized and again when a shell procedure is spawned.
133 */
134
135void
136initvar() {
137	const struct varinit *ip;
138	struct var *vp;
139	struct var **vpp;
140
141	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
142		if ((vp->flags & VEXPORT) == 0) {
143			vpp = hashvar(ip->text);
144			vp->next = *vpp;
145			*vpp = vp;
146			vp->text = ip->text;
147			vp->flags = ip->flags;
148		}
149	}
150	/*
151	 * PS1 depends on uid
152	 */
153	if ((vps1.flags & VEXPORT) == 0) {
154		vpp = hashvar("PS1=");
155		vps1.next = *vpp;
156		*vpp = &vps1;
157		vps1.text = geteuid() ? "PS1=$ " : "PS1=# ";
158		vps1.flags = VSTRFIXED|VTEXTFIXED;
159	}
160}
161
162/*
163 * Set the value of a variable.  The flags argument is ored with the
164 * flags of the variable.  If val is NULL, the variable is unset.
165 */
166
167void
168setvar(name, val, flags)
169	char *name, *val;
170	{
171	char *p, *q;
172	int len;
173	int namelen;
174	char *nameeq;
175	int isbad;
176
177	isbad = 0;
178	p = name;
179	if (! is_name(*p++))
180		isbad = 1;
181	for (;;) {
182		if (! is_in_name(*p)) {
183			if (*p == '\0' || *p == '=')
184				break;
185			isbad = 1;
186		}
187		p++;
188	}
189	namelen = p - name;
190	if (isbad)
191		error("%.*s: bad variable name", namelen, name);
192	len = namelen + 2;		/* 2 is space for '=' and '\0' */
193	if (val == NULL) {
194		flags |= VUNSET;
195	} else {
196		len += strlen(val);
197	}
198	p = nameeq = ckmalloc(len);
199	q = name;
200	while (--namelen >= 0)
201		*p++ = *q++;
202	*p++ = '=';
203	*p = '\0';
204	if (val)
205		scopy(val, p);
206	setvareq(nameeq, flags);
207}
208
209
210
211/*
212 * Same as setvar except that the variable and value are passed in
213 * the first argument as name=value.  Since the first argument will
214 * be actually stored in the table, it should not be a string that
215 * will go away.
216 */
217
218void
219setvareq(s, flags)
220	char *s;
221	{
222	struct var *vp, **vpp;
223
224	vpp = hashvar(s);
225	for (vp = *vpp ; vp ; vp = vp->next) {
226		if (varequal(s, vp->text)) {
227			if (vp->flags & VREADONLY) {
228				int len = strchr(s, '=') - s;
229				error("%.*s: is read only", len, s);
230			}
231			INTOFF;
232			if (vp == &vpath)
233				changepath(s + 5);	/* 5 = strlen("PATH=") */
234			if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
235				ckfree(vp->text);
236			vp->flags &=~ (VTEXTFIXED|VSTACK|VUNSET);
237			vp->flags |= flags;
238			vp->text = s;
239			if (vp == &vmpath || (vp == &vmail && ! mpathset()))
240				chkmail(1);
241			if (vp == &vhistsize)
242				sethistsize();
243			INTON;
244			return;
245		}
246	}
247	/* not found */
248	vp = ckmalloc(sizeof (*vp));
249	vp->flags = flags;
250	vp->text = s;
251	vp->next = *vpp;
252	*vpp = vp;
253}
254
255
256
257/*
258 * Process a linked list of variable assignments.
259 */
260
261void
262listsetvar(list)
263	struct strlist *list;
264	{
265	struct strlist *lp;
266
267	INTOFF;
268	for (lp = list ; lp ; lp = lp->next) {
269		setvareq(savestr(lp->text), 0);
270	}
271	INTON;
272}
273
274
275
276/*
277 * Find the value of a variable.  Returns NULL if not set.
278 */
279
280char *
281lookupvar(name)
282	char *name;
283	{
284	struct var *v;
285
286	for (v = *hashvar(name) ; v ; v = v->next) {
287		if (varequal(v->text, name)) {
288			if (v->flags & VUNSET)
289				return NULL;
290			return strchr(v->text, '=') + 1;
291		}
292	}
293	return NULL;
294}
295
296
297
298/*
299 * Search the environment of a builtin command.  If the second argument
300 * is nonzero, return the value of a variable even if it hasn't been
301 * exported.
302 */
303
304char *
305bltinlookup(name, doall)
306	char *name;
307	{
308	struct strlist *sp;
309	struct var *v;
310
311	for (sp = cmdenviron ; sp ; sp = sp->next) {
312		if (varequal(sp->text, name))
313			return strchr(sp->text, '=') + 1;
314	}
315	for (v = *hashvar(name) ; v ; v = v->next) {
316		if (varequal(v->text, name)) {
317			if (v->flags & VUNSET
318			 || ! doall && (v->flags & VEXPORT) == 0)
319				return NULL;
320			return strchr(v->text, '=') + 1;
321		}
322	}
323	return NULL;
324}
325
326
327
328/*
329 * Generate a list of exported variables.  This routine is used to construct
330 * the third argument to execve when executing a program.
331 */
332
333char **
334environment() {
335	int nenv;
336	struct var **vpp;
337	struct var *vp;
338	char **env, **ep;
339
340	nenv = 0;
341	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
342		for (vp = *vpp ; vp ; vp = vp->next)
343			if (vp->flags & VEXPORT)
344				nenv++;
345	}
346	ep = env = stalloc((nenv + 1) * sizeof *env);
347	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
348		for (vp = *vpp ; vp ; vp = vp->next)
349			if (vp->flags & VEXPORT)
350				*ep++ = vp->text;
351	}
352	*ep = NULL;
353	return env;
354}
355
356
357/*
358 * Called when a shell procedure is invoked to clear out nonexported
359 * variables.  It is also necessary to reallocate variables of with
360 * VSTACK set since these are currently allocated on the stack.
361 */
362
363#ifdef mkinit
364MKINIT void shprocvar();
365
366SHELLPROC {
367	shprocvar();
368}
369#endif
370
371void
372shprocvar() {
373	struct var **vpp;
374	struct var *vp, **prev;
375
376	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
377		for (prev = vpp ; (vp = *prev) != NULL ; ) {
378			if ((vp->flags & VEXPORT) == 0) {
379				*prev = vp->next;
380				if ((vp->flags & VTEXTFIXED) == 0)
381					ckfree(vp->text);
382				if ((vp->flags & VSTRFIXED) == 0)
383					ckfree(vp);
384			} else {
385				if (vp->flags & VSTACK) {
386					vp->text = savestr(vp->text);
387					vp->flags &=~ VSTACK;
388				}
389				prev = &vp->next;
390			}
391		}
392	}
393	initvar();
394}
395
396
397
398/*
399 * Command to list all variables which are set.  Currently this command
400 * is invoked from the set command when the set command is called without
401 * any variables.
402 */
403
404int
405showvarscmd(argc, argv)  char **argv; {
406	struct var **vpp;
407	struct var *vp;
408
409	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
410		for (vp = *vpp ; vp ; vp = vp->next) {
411			if ((vp->flags & VUNSET) == 0)
412				out1fmt("%s\n", vp->text);
413		}
414	}
415	return 0;
416}
417
418
419
420/*
421 * The export and readonly commands.
422 */
423
424int
425exportcmd(argc, argv)  char **argv; {
426	struct var **vpp;
427	struct var *vp;
428	char *name;
429	char *p;
430	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
431
432	listsetvar(cmdenviron);
433	if (argc > 1) {
434		while ((name = *argptr++) != NULL) {
435			if ((p = strchr(name, '=')) != NULL) {
436				p++;
437			} else {
438				vpp = hashvar(name);
439				for (vp = *vpp ; vp ; vp = vp->next) {
440					if (varequal(vp->text, name)) {
441						vp->flags |= flag;
442						goto found;
443					}
444				}
445			}
446			setvar(name, p, flag);
447found:;
448		}
449	} else {
450		for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
451			for (vp = *vpp ; vp ; vp = vp->next) {
452				if (vp->flags & flag) {
453					for (p = vp->text ; *p != '=' ; p++)
454						out1c(*p);
455					out1c('\n');
456				}
457			}
458		}
459	}
460	return 0;
461}
462
463
464/*
465 * The "local" command.
466 */
467
468localcmd(argc, argv)  char **argv; {
469	char *name;
470
471	if (! in_function())
472		error("Not in a function");
473	while ((name = *argptr++) != NULL) {
474		mklocal(name);
475	}
476	return 0;
477}
478
479
480/*
481 * Make a variable a local variable.  When a variable is made local, it's
482 * value and flags are saved in a localvar structure.  The saved values
483 * will be restored when the shell function returns.  We handle the name
484 * "-" as a special case.
485 */
486
487void
488mklocal(name)
489	char *name;
490	{
491	struct localvar *lvp;
492	struct var **vpp;
493	struct var *vp;
494
495	INTOFF;
496	lvp = ckmalloc(sizeof (struct localvar));
497	if (name[0] == '-' && name[1] == '\0') {
498		lvp->text = ckmalloc(sizeof optlist);
499		bcopy(optlist, lvp->text, sizeof optlist);
500		vp = NULL;
501	} else {
502		vpp = hashvar(name);
503		for (vp = *vpp ; vp && ! varequal(vp->text, name) ; vp = vp->next);
504		if (vp == NULL) {
505			if (strchr(name, '='))
506				setvareq(savestr(name), VSTRFIXED);
507			else
508				setvar(name, NULL, VSTRFIXED);
509			vp = *vpp;	/* the new variable */
510			lvp->text = NULL;
511			lvp->flags = VUNSET;
512		} else {
513			lvp->text = vp->text;
514			lvp->flags = vp->flags;
515			vp->flags |= VSTRFIXED|VTEXTFIXED;
516			if (strchr(name, '='))
517				setvareq(savestr(name), 0);
518		}
519	}
520	lvp->vp = vp;
521	lvp->next = localvars;
522	localvars = lvp;
523	INTON;
524}
525
526
527/*
528 * Called after a function returns.
529 */
530
531void
532poplocalvars() {
533	struct localvar *lvp;
534	struct var *vp;
535
536	while ((lvp = localvars) != NULL) {
537		localvars = lvp->next;
538		vp = lvp->vp;
539		if (vp == NULL) {	/* $- saved */
540			bcopy(lvp->text, optlist, sizeof optlist);
541			ckfree(lvp->text);
542		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
543			(void)unsetvar(vp->text);
544		} else {
545			if ((vp->flags & VTEXTFIXED) == 0)
546				ckfree(vp->text);
547			vp->flags = lvp->flags;
548			vp->text = lvp->text;
549		}
550		ckfree(lvp);
551	}
552}
553
554
555setvarcmd(argc, argv)  char **argv; {
556	if (argc <= 2)
557		return unsetcmd(argc, argv);
558	else if (argc == 3)
559		setvar(argv[1], argv[2], 0);
560	else
561		error("List assignment not implemented");
562	return 0;
563}
564
565
566/*
567 * The unset builtin command.  We unset the function before we unset the
568 * variable to allow a function to be unset when there is a readonly variable
569 * with the same name.
570 */
571
572unsetcmd(argc, argv)  char **argv; {
573	char **ap;
574	int i;
575	int flg_func = 0;
576	int flg_var = 0;
577	int ret = 0;
578
579	while ((i = nextopt("vf")) != '\0') {
580		if (i == 'f')
581			flg_func = 1;
582		else
583			flg_var = 1;
584	}
585	if (flg_func == 0 && flg_var == 0)
586		flg_var = 1;
587
588	for (ap = argptr; *ap ; ap++) {
589		if (flg_func)
590			ret |= unsetfunc(*ap);
591		if (flg_var)
592			ret |= unsetvar(*ap);
593	}
594	return ret;
595}
596
597
598/*
599 * Unset the specified variable.
600 */
601
602STATIC int
603unsetvar(s)
604	char *s;
605	{
606	struct var **vpp;
607	struct var *vp;
608
609	vpp = hashvar(s);
610	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
611		if (varequal(vp->text, s)) {
612			if (vp->flags & VREADONLY)
613				return (1);
614			INTOFF;
615			if (*(strchr(vp->text, '=') + 1) != '\0')
616				setvar(s, nullstr, 0);
617			vp->flags &=~ VEXPORT;
618			vp->flags |= VUNSET;
619			if ((vp->flags & VSTRFIXED) == 0) {
620				if ((vp->flags & VTEXTFIXED) == 0)
621					ckfree(vp->text);
622				*vpp = vp->next;
623				ckfree(vp);
624			}
625			INTON;
626			return (0);
627		}
628	}
629
630	return (1);
631}
632
633
634
635/*
636 * Find the appropriate entry in the hash table from the name.
637 */
638
639STATIC struct var **
640hashvar(p)
641	register char *p;
642	{
643	unsigned int hashval;
644
645	hashval = *p << 4;
646	while (*p && *p != '=')
647		hashval += *p++;
648	return &vartab[hashval % VTABSIZE];
649}
650
651
652
653/*
654 * Returns true if the two strings specify the same varable.  The first
655 * variable name is terminated by '='; the second may be terminated by
656 * either '=' or '\0'.
657 */
658
659STATIC int
660varequal(p, q)
661	register char *p, *q;
662	{
663	while (*p == *q++) {
664		if (*p++ == '=')
665			return 1;
666	}
667	if (*p == '=' && *(q - 1) == '\0')
668		return 1;
669	return 0;
670}
671