var.c revision 221559 
1330569Sgordon/*-
2330569Sgordon * Copyright (c) 1991, 1993
3330569Sgordon *	The Regents of the University of California.  All rights reserved.
4330569Sgordon *
5330569Sgordon * This code is derived from software contributed to Berkeley by
6330569Sgordon * Kenneth Almquist.
7330569Sgordon *
8330569Sgordon * Redistribution and use in source and binary forms, with or without
9330569Sgordon * modification, are permitted provided that the following conditions
10330569Sgordon * 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
35static char sccsid[] = "@(#)var.c	8.3 (Berkeley) 5/4/95";
36#endif
37#endif /* not lint */
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD: head/bin/sh/var.c 221559 2011-05-06 22:31:27Z jilles $");
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#ifndef NO_HISTORY
67#include "myhistedit.h"
68#endif
69
70
71#define VTABSIZE 39
72
73
74struct varinit {
75	struct var *var;
76	int flags;
77	const char *text;
78	void (*func)(const char *);
79};
80
81
82#ifndef NO_HISTORY
83struct var vhistsize;
84struct var vterm;
85#endif
86struct var vifs;
87struct var vmail;
88struct var vmpath;
89struct var vpath;
90struct var vppid;
91struct var vps1;
92struct var vps2;
93struct var vps4;
94struct var vvers;
95static struct var voptind;
96
97static const struct varinit varinit[] = {
98#ifndef NO_HISTORY
99	{ &vhistsize,	VUNSET,				"HISTSIZE=",
100	  sethistsize },
101#endif
102	{ &vifs,	0,				"IFS= \t\n",
103	  NULL },
104	{ &vmail,	VUNSET,				"MAIL=",
105	  NULL },
106	{ &vmpath,	VUNSET,				"MAILPATH=",
107	  NULL },
108	{ &vpath,	0,				"PATH=" _PATH_DEFPATH,
109	  changepath },
110	{ &vppid,	VUNSET,				"PPID=",
111	  NULL },
112	/*
113	 * vps1 depends on uid
114	 */
115	{ &vps2,	0,				"PS2=> ",
116	  NULL },
117	{ &vps4,	0,				"PS4=+ ",
118	  NULL },
119#ifndef NO_HISTORY
120	{ &vterm,	VUNSET,				"TERM=",
121	  setterm },
122#endif
123	{ &voptind,	0,				"OPTIND=1",
124	  getoptsreset },
125	{ NULL,	0,				NULL,
126	  NULL }
127};
128
129static struct var *vartab[VTABSIZE];
130
131static const char *const locale_names[7] = {
132	"LC_COLLATE", "LC_CTYPE", "LC_MONETARY",
133	"LC_NUMERIC", "LC_TIME", "LC_MESSAGES", NULL
134};
135static const int locale_categories[7] = {
136	LC_COLLATE, LC_CTYPE, LC_MONETARY, LC_NUMERIC, LC_TIME, LC_MESSAGES, 0
137};
138
139static struct var **hashvar(const char *);
140static int varequal(const char *, const char *);
141static int localevar(const char *);
142
143/*
144 * Initialize the variable symbol tables and import the environment.
145 */
146
147#ifdef mkinit
148INCLUDE "var.h"
149MKINIT char **environ;
150INIT {
151	char **envp;
152
153	initvar();
154	for (envp = environ ; *envp ; envp++) {
155		if (strchr(*envp, '=')) {
156			setvareq(*envp, VEXPORT|VTEXTFIXED);
157		}
158	}
159}
160#endif
161
162
163/*
164 * This routine initializes the builtin variables.  It is called when the
165 * shell is initialized.
166 */
167
168void
169initvar(void)
170{
171	char ppid[20];
172	const struct varinit *ip;
173	struct var *vp;
174	struct var **vpp;
175
176	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
177		if ((vp->flags & VEXPORT) == 0) {
178			vpp = hashvar(ip->text);
179			vp->next = *vpp;
180			*vpp = vp;
181			vp->text = __DECONST(char *, ip->text);
182			vp->flags = ip->flags | VSTRFIXED | VTEXTFIXED;
183			vp->func = ip->func;
184		}
185	}
186	/*
187	 * PS1 depends on uid
188	 */
189	if ((vps1.flags & VEXPORT) == 0) {
190		vpp = hashvar("PS1=");
191		vps1.next = *vpp;
192		*vpp = &vps1;
193		vps1.text = __DECONST(char *, geteuid() ? "PS1=$ " : "PS1=# ");
194		vps1.flags = VSTRFIXED|VTEXTFIXED;
195	}
196	if ((vppid.flags & VEXPORT) == 0) {
197		fmtstr(ppid, sizeof(ppid), "%d", (int)getppid());
198		setvarsafe("PPID", ppid, 0);
199	}
200}
201
202/*
203 * Safe version of setvar, returns 1 on success 0 on failure.
204 */
205
206int
207setvarsafe(const char *name, const char *val, int flags)
208{
209	struct jmploc jmploc;
210	struct jmploc *const savehandler = handler;
211	int err = 0;
212	int inton;
213
214	inton = is_int_on();
215	if (setjmp(jmploc.loc))
216		err = 1;
217	else {
218		handler = &jmploc;
219		setvar(name, val, flags);
220	}
221	handler = savehandler;
222	SETINTON(inton);
223	return err;
224}
225
226/*
227 * Set the value of a variable.  The flags argument is stored with the
228 * flags of the variable.  If val is NULL, the variable is unset.
229 */
230
231void
232setvar(const char *name, const char *val, int flags)
233{
234	const char *p;
235	int len;
236	int namelen;
237	char *nameeq;
238	int isbad;
239
240	isbad = 0;
241	p = name;
242	if (! is_name(*p))
243		isbad = 1;
244	p++;
245	for (;;) {
246		if (! is_in_name(*p)) {
247			if (*p == '\0' || *p == '=')
248				break;
249			isbad = 1;
250		}
251		p++;
252	}
253	namelen = p - name;
254	if (isbad)
255		error("%.*s: bad variable name", namelen, name);
256	len = namelen + 2;		/* 2 is space for '=' and '\0' */
257	if (val == NULL) {
258		flags |= VUNSET;
259	} else {
260		len += strlen(val);
261	}
262	nameeq = ckmalloc(len);
263	memcpy(nameeq, name, namelen);
264	nameeq[namelen] = '=';
265	if (val)
266		scopy(val, nameeq + namelen + 1);
267	else
268		nameeq[namelen + 1] = '\0';
269	setvareq(nameeq, flags);
270}
271
272static int
273localevar(const char *s)
274{
275	const char *const *ss;
276
277	if (*s != 'L')
278		return 0;
279	if (varequal(s + 1, "ANG"))
280		return 1;
281	if (strncmp(s + 1, "C_", 2) != 0)
282		return 0;
283	if (varequal(s + 3, "ALL"))
284		return 1;
285	for (ss = locale_names; *ss ; ss++)
286		if (varequal(s + 3, *ss + 3))
287			return 1;
288	return 0;
289}
290
291
292/*
293 * Sets/unsets an environment variable from a pointer that may actually be a
294 * pointer into environ where the string should not be manipulated.
295 */
296static void
297change_env(const char *s, int set)
298{
299	char *eqp;
300	char *ss;
301
302	ss = savestr(s);
303	if ((eqp = strchr(ss, '=')) != NULL)
304		*eqp = '\0';
305	if (set && eqp != NULL)
306		(void) setenv(ss, eqp + 1, 1);
307	else
308		(void) unsetenv(ss);
309	ckfree(ss);
310
311	return;
312}
313
314
315/*
316 * Same as setvar except that the variable and value are passed in
317 * the first argument as name=value.  Since the first argument will
318 * be actually stored in the table, it should not be a string that
319 * will go away.
320 */
321
322void
323setvareq(char *s, int flags)
324{
325	struct var *vp, **vpp;
326	int len;
327
328	if (aflag)
329		flags |= VEXPORT;
330	vpp = hashvar(s);
331	for (vp = *vpp ; vp ; vp = vp->next) {
332		if (varequal(s, vp->text)) {
333			if (vp->flags & VREADONLY) {
334				len = strchr(s, '=') - s;
335				error("%.*s: is read only", len, s);
336			}
337			if (flags & VNOSET)
338				return;
339			INTOFF;
340
341			if (vp->func && (flags & VNOFUNC) == 0)
342				(*vp->func)(strchr(s, '=') + 1);
343
344			if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
345				ckfree(vp->text);
346
347			vp->flags &= ~(VTEXTFIXED|VSTACK|VUNSET);
348			vp->flags |= flags;
349			vp->text = s;
350
351			/*
352			 * We could roll this to a function, to handle it as
353			 * a regular variable function callback, but why bother?
354			 *
355			 * Note: this assumes iflag is not set to 1 initially.
356			 * As part of init(), this is called before arguments
357			 * are looked at.
358			 */
359			if ((vp == &vmpath || (vp == &vmail && ! mpathset())) &&
360			    iflag == 1)
361				chkmail(1);
362			if ((vp->flags & VEXPORT) && localevar(s)) {
363				change_env(s, 1);
364				(void) setlocale(LC_ALL, "");
365				updatecharset();
366			}
367			INTON;
368			return;
369		}
370	}
371	/* not found */
372	if (flags & VNOSET)
373		return;
374	vp = ckmalloc(sizeof (*vp));
375	vp->flags = flags;
376	vp->text = s;
377	vp->next = *vpp;
378	vp->func = NULL;
379	INTOFF;
380	*vpp = vp;
381	if ((vp->flags & VEXPORT) && localevar(s)) {
382		change_env(s, 1);
383		(void) setlocale(LC_ALL, "");
384		updatecharset();
385	}
386	INTON;
387}
388
389
390
391/*
392 * Process a linked list of variable assignments.
393 */
394
395void
396listsetvar(struct strlist *list, int flags)
397{
398	struct strlist *lp;
399
400	INTOFF;
401	for (lp = list ; lp ; lp = lp->next) {
402		setvareq(savestr(lp->text), flags);
403	}
404	INTON;
405}
406
407
408
409/*
410 * Find the value of a variable.  Returns NULL if not set.
411 */
412
413char *
414lookupvar(const char *name)
415{
416	struct var *v;
417
418	for (v = *hashvar(name) ; v ; v = v->next) {
419		if (varequal(v->text, name)) {
420			if (v->flags & VUNSET)
421				return NULL;
422			return strchr(v->text, '=') + 1;
423		}
424	}
425	return NULL;
426}
427
428
429
430/*
431 * Search the environment of a builtin command.  If the second argument
432 * is nonzero, return the value of a variable even if it hasn't been
433 * exported.
434 */
435
436char *
437bltinlookup(const char *name, int doall)
438{
439	struct strlist *sp;
440	struct var *v;
441	char *result;
442
443	result = NULL;
444	for (sp = cmdenviron ; sp ; sp = sp->next) {
445		if (varequal(sp->text, name))
446			result = strchr(sp->text, '=') + 1;
447	}
448	if (result != NULL)
449		return result;
450	for (v = *hashvar(name) ; v ; v = v->next) {
451		if (varequal(v->text, name)) {
452			if ((v->flags & VUNSET)
453			 || (!doall && (v->flags & VEXPORT) == 0))
454				return NULL;
455			return strchr(v->text, '=') + 1;
456		}
457	}
458	return NULL;
459}
460
461
462/*
463 * Set up locale for a builtin (LANG/LC_* assignments).
464 */
465void
466bltinsetlocale(void)
467{
468	struct strlist *lp;
469	int act = 0;
470	char *loc, *locdef;
471	int i;
472
473	for (lp = cmdenviron ; lp ; lp = lp->next) {
474		if (localevar(lp->text)) {
475			act = 1;
476			break;
477		}
478	}
479	if (!act)
480		return;
481	loc = bltinlookup("LC_ALL", 0);
482	INTOFF;
483	if (loc != NULL) {
484		setlocale(LC_ALL, loc);
485		INTON;
486		updatecharset();
487		return;
488	}
489	locdef = bltinlookup("LANG", 0);
490	for (i = 0; locale_names[i] != NULL; i++) {
491		loc = bltinlookup(locale_names[i], 0);
492		if (loc == NULL)
493			loc = locdef;
494		if (loc != NULL)
495			setlocale(locale_categories[i], loc);
496	}
497	INTON;
498	updatecharset();
499}
500
501/*
502 * Undo the effect of bltinlocaleset().
503 */
504void
505bltinunsetlocale(void)
506{
507	struct strlist *lp;
508
509	INTOFF;
510	for (lp = cmdenviron ; lp ; lp = lp->next) {
511		if (localevar(lp->text)) {
512			setlocale(LC_ALL, "");
513			updatecharset();
514			return;
515		}
516	}
517	INTON;
518}
519
520/*
521 * Update the localeisutf8 flag.
522 */
523void
524updatecharset(void)
525{
526	char *charset;
527
528	charset = nl_langinfo(CODESET);
529	localeisutf8 = !strcmp(charset, "UTF-8");
530}
531
532/*
533 * Generate a list of exported variables.  This routine is used to construct
534 * the third argument to execve when executing a program.
535 */
536
537char **
538environment(void)
539{
540	int nenv;
541	struct var **vpp;
542	struct var *vp;
543	char **env, **ep;
544
545	nenv = 0;
546	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
547		for (vp = *vpp ; vp ; vp = vp->next)
548			if (vp->flags & VEXPORT)
549				nenv++;
550	}
551	ep = env = stalloc((nenv + 1) * sizeof *env);
552	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
553		for (vp = *vpp ; vp ; vp = vp->next)
554			if (vp->flags & VEXPORT)
555				*ep++ = vp->text;
556	}
557	*ep = NULL;
558	return env;
559}
560
561
562static int
563var_compare(const void *a, const void *b)
564{
565	const char *const *sa, *const *sb;
566
567	sa = a;
568	sb = b;
569	/*
570	 * This compares two var=value strings which creates a different
571	 * order from what you would probably expect.  POSIX is somewhat
572	 * ambiguous on what should be sorted exactly.
573	 */
574	return strcoll(*sa, *sb);
575}
576
577
578/*
579 * Command to list all variables which are set.  This is invoked from the
580 * set command when it is called without any options or operands.
581 */
582
583int
584showvarscmd(int argc __unused, char **argv __unused)
585{
586	struct var **vpp;
587	struct var *vp;
588	const char *s;
589	const char **vars;
590	int i, n;
591
592	/*
593	 * POSIX requires us to sort the variables.
594	 */
595	n = 0;
596	for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) {
597		for (vp = *vpp; vp; vp = vp->next) {
598			if (!(vp->flags & VUNSET))
599				n++;
600		}
601	}
602
603	INTON;
604	vars = ckmalloc(n * sizeof(*vars));
605	i = 0;
606	for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) {
607		for (vp = *vpp; vp; vp = vp->next) {
608			if (!(vp->flags & VUNSET))
609				vars[i++] = vp->text;
610		}
611	}
612
613	qsort(vars, n, sizeof(*vars), var_compare);
614	for (i = 0; i < n; i++) {
615		s = strchr(vars[i], '=');
616		s++;
617		outbin(vars[i], s - vars[i], out1);
618		out1qstr(s);
619		out1c('\n');
620	}
621	ckfree(vars);
622	INTOFF;
623
624	return 0;
625}
626
627
628
629/*
630 * The export and readonly commands.
631 */
632
633int
634exportcmd(int argc, char **argv)
635{
636	struct var **vpp;
637	struct var *vp;
638	char *name;
639	char *p;
640	char *cmdname;
641	int ch, values;
642	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
643
644	cmdname = argv[0];
645	optreset = optind = 1;
646	opterr = 0;
647	values = 0;
648	while ((ch = getopt(argc, argv, "p")) != -1) {
649		switch (ch) {
650		case 'p':
651			values = 1;
652			break;
653		case '?':
654		default:
655			error("unknown option: -%c", optopt);
656		}
657	}
658	argc -= optind;
659	argv += optind;
660
661	if (values && argc != 0)
662		error("-p requires no arguments");
663	if (argc != 0) {
664		while ((name = *argv++) != NULL) {
665			if ((p = strchr(name, '=')) != NULL) {
666				p++;
667			} else {
668				vpp = hashvar(name);
669				for (vp = *vpp ; vp ; vp = vp->next) {
670					if (varequal(vp->text, name)) {
671
672						vp->flags |= flag;
673						if ((vp->flags & VEXPORT) && localevar(vp->text)) {
674							change_env(vp->text, 1);
675							(void) setlocale(LC_ALL, "");
676							updatecharset();
677						}
678						goto found;
679					}
680				}
681			}
682			setvar(name, p, flag);
683found:;
684		}
685	} else {
686		for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
687			for (vp = *vpp ; vp ; vp = vp->next) {
688				if (vp->flags & flag) {
689					if (values) {
690						out1str(cmdname);
691						out1c(' ');
692					}
693					p = strchr(vp->text, '=');
694					if (values && !(vp->flags & VUNSET)) {
695						p++;
696						outbin(vp->text, p - vp->text,
697						    out1);
698						out1qstr(p);
699					} else
700						outbin(vp->text, p - vp->text,
701						    out1);
702					out1c('\n');
703				}
704			}
705		}
706	}
707	return 0;
708}
709
710
711/*
712 * The "local" command.
713 */
714
715int
716localcmd(int argc __unused, char **argv __unused)
717{
718	char *name;
719
720	if (! in_function())
721		error("Not in a function");
722	while ((name = *argptr++) != NULL) {
723		mklocal(name);
724	}
725	return 0;
726}
727
728
729/*
730 * Make a variable a local variable.  When a variable is made local, it's
731 * value and flags are saved in a localvar structure.  The saved values
732 * will be restored when the shell function returns.  We handle the name
733 * "-" as a special case.
734 */
735
736void
737mklocal(char *name)
738{
739	struct localvar *lvp;
740	struct var **vpp;
741	struct var *vp;
742
743	INTOFF;
744	lvp = ckmalloc(sizeof (struct localvar));
745	if (name[0] == '-' && name[1] == '\0') {
746		lvp->text = ckmalloc(sizeof optlist);
747		memcpy(lvp->text, optlist, sizeof optlist);
748		vp = NULL;
749	} else {
750		vpp = hashvar(name);
751		for (vp = *vpp ; vp && ! varequal(vp->text, name) ; vp = vp->next);
752		if (vp == NULL) {
753			if (strchr(name, '='))
754				setvareq(savestr(name), VSTRFIXED);
755			else
756				setvar(name, NULL, VSTRFIXED);
757			vp = *vpp;	/* the new variable */
758			lvp->text = NULL;
759			lvp->flags = VUNSET;
760		} else {
761			lvp->text = vp->text;
762			lvp->flags = vp->flags;
763			vp->flags |= VSTRFIXED|VTEXTFIXED;
764			if (strchr(name, '='))
765				setvareq(savestr(name), 0);
766		}
767	}
768	lvp->vp = vp;
769	lvp->next = localvars;
770	localvars = lvp;
771	INTON;
772}
773
774
775/*
776 * Called after a function returns.
777 */
778
779void
780poplocalvars(void)
781{
782	struct localvar *lvp;
783	struct var *vp;
784
785	while ((lvp = localvars) != NULL) {
786		localvars = lvp->next;
787		vp = lvp->vp;
788		if (vp == NULL) {	/* $- saved */
789			memcpy(optlist, lvp->text, sizeof optlist);
790			ckfree(lvp->text);
791			optschanged();
792		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
793			(void)unsetvar(vp->text);
794		} else {
795			if ((vp->flags & VTEXTFIXED) == 0)
796				ckfree(vp->text);
797			vp->flags = lvp->flags;
798			vp->text = lvp->text;
799		}
800		ckfree(lvp);
801	}
802}
803
804
805int
806setvarcmd(int argc, char **argv)
807{
808	if (argc <= 2)
809		return unsetcmd(argc, argv);
810	else if (argc == 3)
811		setvar(argv[1], argv[2], 0);
812	else
813		error("too many arguments");
814	return 0;
815}
816
817
818/*
819 * The unset builtin command.
820 */
821
822int
823unsetcmd(int argc __unused, char **argv __unused)
824{
825	char **ap;
826	int i;
827	int flg_func = 0;
828	int flg_var = 0;
829	int ret = 0;
830
831	while ((i = nextopt("vf")) != '\0') {
832		if (i == 'f')
833			flg_func = 1;
834		else
835			flg_var = 1;
836	}
837	if (flg_func == 0 && flg_var == 0)
838		flg_var = 1;
839
840	for (ap = argptr; *ap ; ap++) {
841		if (flg_func)
842			ret |= unsetfunc(*ap);
843		if (flg_var)
844			ret |= unsetvar(*ap);
845	}
846	return ret;
847}
848
849
850/*
851 * Unset the specified variable.
852 */
853
854int
855unsetvar(const char *s)
856{
857	struct var **vpp;
858	struct var *vp;
859
860	vpp = hashvar(s);
861	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
862		if (varequal(vp->text, s)) {
863			if (vp->flags & VREADONLY)
864				return (1);
865			INTOFF;
866			if (*(strchr(vp->text, '=') + 1) != '\0')
867				setvar(s, nullstr, 0);
868			if ((vp->flags & VEXPORT) && localevar(vp->text)) {
869				change_env(s, 0);
870				setlocale(LC_ALL, "");
871				updatecharset();
872			}
873			vp->flags &= ~VEXPORT;
874			vp->flags |= VUNSET;
875			if ((vp->flags & VSTRFIXED) == 0) {
876				if ((vp->flags & VTEXTFIXED) == 0)
877					ckfree(vp->text);
878				*vpp = vp->next;
879				ckfree(vp);
880			}
881			INTON;
882			return (0);
883		}
884	}
885
886	return (0);
887}
888
889
890
891/*
892 * Find the appropriate entry in the hash table from the name.
893 */
894
895static struct var **
896hashvar(const char *p)
897{
898	unsigned int hashval;
899
900	hashval = ((unsigned char) *p) << 4;
901	while (*p && *p != '=')
902		hashval += (unsigned char) *p++;
903	return &vartab[hashval % VTABSIZE];
904}
905
906
907
908/*
909 * Returns true if the two strings specify the same varable.  The first
910 * variable name is terminated by '='; the second may be terminated by
911 * either '=' or '\0'.
912 */
913
914static int
915varequal(const char *p, const char *q)
916{
917	while (*p == *q++) {
918		if (*p++ == '=')
919			return 1;
920	}
921	if (*p == '=' && *(q - 1) == '\0')
922		return 1;
923	return 0;
924}
925