xref: /freebsd/bin/sh/var.c (revision 7bd6fde3) 
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 
51 #include "shell.h"
52 #include "output.h"
53 #include "expand.h"
54 #include "nodes.h"	/* for other headers */
55 #include "eval.h"	/* defines cmdenviron */
56 #include "exec.h"
57 #include "syntax.h"
58 #include "options.h"
59 #include "mail.h"
60 #include "var.h"
61 #include "memalloc.h"
62 #include "error.h"
63 #include "mystring.h"
64 #include "parser.h"
65 #ifndef NO_HISTORY
66 #include "myhistedit.h"
67 #endif
68 
69 
70 #define VTABSIZE 39
71 
72 
73 struct varinit {
74 	struct var *var;
75 	int flags;
76 	char *text;
77 	void (*func)(const char *);
78 };
79 
80 
81 #ifndef NO_HISTORY
82 struct var vhistsize;
83 #endif
84 struct var vifs;
85 struct var vmail;
86 struct var vmpath;
87 struct var vpath;
88 struct var vppid;
89 struct var vps1;
90 struct var vps2;
91 struct var vps4;
92 struct var vvers;
93 STATIC struct var voptind;
94 
95 STATIC const struct varinit varinit[] = {
96 #ifndef NO_HISTORY
97 	{ &vhistsize,	VSTRFIXED|VTEXTFIXED|VUNSET,	"HISTSIZE=",
98 	  sethistsize },
99 #endif
100 	{ &vifs,	VSTRFIXED|VTEXTFIXED,		"IFS= \t\n",
101 	  NULL },
102 	{ &vmail,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAIL=",
103 	  NULL },
104 	{ &vmpath,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAILPATH=",
105 	  NULL },
106 	{ &vpath,	VSTRFIXED|VTEXTFIXED,		"PATH=" _PATH_DEFPATH,
107 	  changepath },
108 	{ &vppid,	VSTRFIXED|VTEXTFIXED|VUNSET,	"PPID=",
109 	  NULL },
110 	/*
111 	 * vps1 depends on uid
112 	 */
113 	{ &vps2,	VSTRFIXED|VTEXTFIXED,		"PS2=> ",
114 	  NULL },
115 	{ &vps4,	VSTRFIXED|VTEXTFIXED,		"PS4=+ ",
116 	  NULL },
117 	{ &voptind,	VSTRFIXED|VTEXTFIXED,		"OPTIND=1",
118 	  getoptsreset },
119 	{ NULL,	0,				NULL,
120 	  NULL }
121 };
122 
123 STATIC struct var *vartab[VTABSIZE];
124 
125 STATIC struct var **hashvar(char *);
126 STATIC int varequal(char *, char *);
127 STATIC int localevar(char *);
128 
129 /*
130  * Initialize the variable symbol tables and import the environment.
131  */
132 
133 #ifdef mkinit
134 INCLUDE "var.h"
135 INIT {
136 	char **envp;
137 	extern char **environ;
138 
139 	initvar();
140 	for (envp = environ ; *envp ; envp++) {
141 		if (strchr(*envp, '=')) {
142 			setvareq(*envp, VEXPORT|VTEXTFIXED);
143 		}
144 	}
145 }
146 #endif
147 
148 
149 /*
150  * This routine initializes the builtin variables.  It is called when the
151  * shell is initialized and again when a shell procedure is spawned.
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 
162 	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
163 		if ((vp->flags & VEXPORT) == 0) {
164 			vpp = hashvar(ip->text);
165 			vp->next = *vpp;
166 			*vpp = vp;
167 			vp->text = ip->text;
168 			vp->flags = ip->flags;
169 			vp->func = ip->func;
170 		}
171 	}
172 	/*
173 	 * PS1 depends on uid
174 	 */
175 	if ((vps1.flags & VEXPORT) == 0) {
176 		vpp = hashvar("PS1=");
177 		vps1.next = *vpp;
178 		*vpp = &vps1;
179 		vps1.text = geteuid() ? "PS1=$ " : "PS1=# ";
180 		vps1.flags = VSTRFIXED|VTEXTFIXED;
181 	}
182 	if ((vppid.flags & VEXPORT) == 0) {
183 		fmtstr(ppid, sizeof(ppid), "%d", (int)getppid());
184 		setvarsafe("PPID", ppid, 0);
185 	}
186 }
187 
188 /*
189  * Safe version of setvar, returns 1 on success 0 on failure.
190  */
191 
192 int
193 setvarsafe(char *name, char *val, int flags)
194 {
195 	struct jmploc jmploc;
196 	struct jmploc *volatile savehandler = handler;
197 	int err = 0;
198 #if __GNUC__
199 	/* Avoid longjmp clobbering */
200 	(void) &err;
201 #endif
202 
203 	if (setjmp(jmploc.loc))
204 		err = 1;
205 	else {
206 		handler = &jmploc;
207 		setvar(name, val, flags);
208 	}
209 	handler = savehandler;
210 	return err;
211 }
212 
213 /*
214  * Set the value of a variable.  The flags argument is stored with the
215  * flags of the variable.  If val is NULL, the variable is unset.
216  */
217 
218 void
219 setvar(char *name, char *val, int flags)
220 {
221 	char *p, *q;
222 	int len;
223 	int namelen;
224 	char *nameeq;
225 	int isbad;
226 
227 	isbad = 0;
228 	p = name;
229 	if (! is_name(*p))
230 		isbad = 1;
231 	p++;
232 	for (;;) {
233 		if (! is_in_name(*p)) {
234 			if (*p == '\0' || *p == '=')
235 				break;
236 			isbad = 1;
237 		}
238 		p++;
239 	}
240 	namelen = p - name;
241 	if (isbad)
242 		error("%.*s: bad variable name", namelen, name);
243 	len = namelen + 2;		/* 2 is space for '=' and '\0' */
244 	if (val == NULL) {
245 		flags |= VUNSET;
246 	} else {
247 		len += strlen(val);
248 	}
249 	p = nameeq = ckmalloc(len);
250 	q = name;
251 	while (--namelen >= 0)
252 		*p++ = *q++;
253 	*p++ = '=';
254 	*p = '\0';
255 	if (val)
256 		scopy(val, p);
257 	setvareq(nameeq, flags);
258 }
259 
260 STATIC int
261 localevar(char *s)
262 {
263 	static char *lnames[7] = {
264 		"ALL", "COLLATE", "CTYPE", "MONETARY",
265 		"NUMERIC", "TIME", NULL
266 	};
267 	char **ss;
268 
269 	if (*s != 'L')
270 		return 0;
271 	if (varequal(s + 1, "ANG"))
272 		return 1;
273 	if (strncmp(s + 1, "C_", 2) != 0)
274 		return 0;
275 	for (ss = lnames; *ss ; ss++)
276 		if (varequal(s + 3, *ss))
277 			return 1;
278 	return 0;
279 }
280 
281 /*
282  * Same as setvar except that the variable and value are passed in
283  * the first argument as name=value.  Since the first argument will
284  * be actually stored in the table, it should not be a string that
285  * will go away.
286  */
287 
288 void
289 setvareq(char *s, int flags)
290 {
291 	struct var *vp, **vpp;
292 	int len;
293 
294 	if (aflag)
295 		flags |= VEXPORT;
296 	vpp = hashvar(s);
297 	for (vp = *vpp ; vp ; vp = vp->next) {
298 		if (varequal(s, vp->text)) {
299 			if (vp->flags & VREADONLY) {
300 				len = strchr(s, '=') - s;
301 				error("%.*s: is read only", len, s);
302 			}
303 			INTOFF;
304 
305 			if (vp->func && (flags & VNOFUNC) == 0)
306 				(*vp->func)(strchr(s, '=') + 1);
307 
308 			if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
309 				ckfree(vp->text);
310 
311 			vp->flags &= ~(VTEXTFIXED|VSTACK|VUNSET);
312 			vp->flags |= flags;
313 			vp->text = s;
314 
315 			/*
316 			 * We could roll this to a function, to handle it as
317 			 * a regular variable function callback, but why bother?
318 			 */
319 			if (vp == &vmpath || (vp == &vmail && ! mpathset()))
320 				chkmail(1);
321 			if ((vp->flags & VEXPORT) && localevar(s)) {
322 				putenv(s);
323 				(void) setlocale(LC_ALL, "");
324 			}
325 			INTON;
326 			return;
327 		}
328 	}
329 	/* not found */
330 	vp = ckmalloc(sizeof (*vp));
331 	vp->flags = flags;
332 	vp->text = s;
333 	vp->next = *vpp;
334 	vp->func = NULL;
335 	INTOFF;
336 	*vpp = vp;
337 	if ((vp->flags & VEXPORT) && localevar(s)) {
338 		putenv(s);
339 		(void) setlocale(LC_ALL, "");
340 	}
341 	INTON;
342 }
343 
344 
345 
346 /*
347  * Process a linked list of variable assignments.
348  */
349 
350 void
351 listsetvar(struct strlist *list)
352 {
353 	struct strlist *lp;
354 
355 	INTOFF;
356 	for (lp = list ; lp ; lp = lp->next) {
357 		setvareq(savestr(lp->text), 0);
358 	}
359 	INTON;
360 }
361 
362 
363 
364 /*
365  * Find the value of a variable.  Returns NULL if not set.
366  */
367 
368 char *
369 lookupvar(char *name)
370 {
371 	struct var *v;
372 
373 	for (v = *hashvar(name) ; v ; v = v->next) {
374 		if (varequal(v->text, name)) {
375 			if (v->flags & VUNSET)
376 				return NULL;
377 			return strchr(v->text, '=') + 1;
378 		}
379 	}
380 	return NULL;
381 }
382 
383 
384 
385 /*
386  * Search the environment of a builtin command.  If the second argument
387  * is nonzero, return the value of a variable even if it hasn't been
388  * exported.
389  */
390 
391 char *
392 bltinlookup(char *name, int doall)
393 {
394 	struct strlist *sp;
395 	struct var *v;
396 
397 	for (sp = cmdenviron ; sp ; sp = sp->next) {
398 		if (varequal(sp->text, name))
399 			return strchr(sp->text, '=') + 1;
400 	}
401 	for (v = *hashvar(name) ; v ; v = v->next) {
402 		if (varequal(v->text, name)) {
403 			if ((v->flags & VUNSET)
404 			 || (!doall && (v->flags & VEXPORT) == 0))
405 				return NULL;
406 			return strchr(v->text, '=') + 1;
407 		}
408 	}
409 	return NULL;
410 }
411 
412 
413 
414 /*
415  * Generate a list of exported variables.  This routine is used to construct
416  * the third argument to execve when executing a program.
417  */
418 
419 char **
420 environment(void)
421 {
422 	int nenv;
423 	struct var **vpp;
424 	struct var *vp;
425 	char **env, **ep;
426 
427 	nenv = 0;
428 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
429 		for (vp = *vpp ; vp ; vp = vp->next)
430 			if (vp->flags & VEXPORT)
431 				nenv++;
432 	}
433 	ep = env = stalloc((nenv + 1) * sizeof *env);
434 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
435 		for (vp = *vpp ; vp ; vp = vp->next)
436 			if (vp->flags & VEXPORT)
437 				*ep++ = vp->text;
438 	}
439 	*ep = NULL;
440 	return env;
441 }
442 
443 
444 /*
445  * Called when a shell procedure is invoked to clear out nonexported
446  * variables.  It is also necessary to reallocate variables of with
447  * VSTACK set since these are currently allocated on the stack.
448  */
449 
450 #ifdef mkinit
451 MKINIT void shprocvar(void);
452 
453 SHELLPROC {
454 	shprocvar();
455 }
456 #endif
457 
458 void
459 shprocvar(void)
460 {
461 	struct var **vpp;
462 	struct var *vp, **prev;
463 
464 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
465 		for (prev = vpp ; (vp = *prev) != NULL ; ) {
466 			if ((vp->flags & VEXPORT) == 0) {
467 				*prev = vp->next;
468 				if ((vp->flags & VTEXTFIXED) == 0)
469 					ckfree(vp->text);
470 				if ((vp->flags & VSTRFIXED) == 0)
471 					ckfree(vp);
472 			} else {
473 				if (vp->flags & VSTACK) {
474 					vp->text = savestr(vp->text);
475 					vp->flags &=~ VSTACK;
476 				}
477 				prev = &vp->next;
478 			}
479 		}
480 	}
481 	initvar();
482 }
483 
484 
485 static int
486 var_compare(const void *a, const void *b)
487 {
488 	const char *const *sa, *const *sb;
489 
490 	sa = a;
491 	sb = b;
492 	/*
493 	 * This compares two var=value strings which creates a different
494 	 * order from what you would probably expect.  POSIX is somewhat
495 	 * ambiguous on what should be sorted exactly.
496 	 */
497 	return strcoll(*sa, *sb);
498 }
499 
500 
501 /*
502  * Command to list all variables which are set.  Currently this command
503  * is invoked from the set command when the set command is called without
504  * any variables.
505  */
506 
507 int
508 showvarscmd(int argc __unused, char **argv __unused)
509 {
510 	struct var **vpp;
511 	struct var *vp;
512 	const char *s;
513 	const char **vars;
514 	int i, n;
515 
516 	/*
517 	 * POSIX requires us to sort the variables.
518 	 */
519 	n = 0;
520 	for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) {
521 		for (vp = *vpp; vp; vp = vp->next) {
522 			if (!(vp->flags & VUNSET))
523 				n++;
524 		}
525 	}
526 
527 	INTON;
528 	vars = ckmalloc(n * sizeof(*vars));
529 	i = 0;
530 	for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) {
531 		for (vp = *vpp; vp; vp = vp->next) {
532 			if (!(vp->flags & VUNSET))
533 				vars[i++] = vp->text;
534 		}
535 	}
536 
537 	qsort(vars, n, sizeof(*vars), var_compare);
538 	for (i = 0; i < n; i++) {
539 		for (s = vars[i]; *s != '='; s++)
540 			out1c(*s);
541 		out1c('=');
542 		out1qstr(s + 1);
543 		out1c('\n');
544 	}
545 	ckfree(vars);
546 	INTOFF;
547 
548 	return 0;
549 }
550 
551 
552 
553 /*
554  * The export and readonly commands.
555  */
556 
557 int
558 exportcmd(int argc, char **argv)
559 {
560 	struct var **vpp;
561 	struct var *vp;
562 	char *name;
563 	char *p;
564 	char *cmdname;
565 	int ch, values;
566 	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
567 
568 	cmdname = argv[0];
569 	optreset = optind = 1;
570 	opterr = 0;
571 	values = 0;
572 	while ((ch = getopt(argc, argv, "p")) != -1) {
573 		switch (ch) {
574 		case 'p':
575 			values = 1;
576 			break;
577 		case '?':
578 		default:
579 			error("unknown option: -%c", optopt);
580 		}
581 	}
582 	argc -= optind;
583 	argv += optind;
584 
585 	if (values && argc != 0)
586 		error("-p requires no arguments");
587 	listsetvar(cmdenviron);
588 	if (argc != 0) {
589 		while ((name = *argv++) != NULL) {
590 			if ((p = strchr(name, '=')) != NULL) {
591 				p++;
592 			} else {
593 				vpp = hashvar(name);
594 				for (vp = *vpp ; vp ; vp = vp->next) {
595 					if (varequal(vp->text, name)) {
596 
597 						vp->flags |= flag;
598 						if ((vp->flags & VEXPORT) && localevar(vp->text)) {
599 							putenv(vp->text);
600 							(void) setlocale(LC_ALL, "");
601 						}
602 						goto found;
603 					}
604 				}
605 			}
606 			setvar(name, p, flag);
607 found:;
608 		}
609 	} else {
610 		for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
611 			for (vp = *vpp ; vp ; vp = vp->next) {
612 				if (vp->flags & flag) {
613 					if (values) {
614 						out1str(cmdname);
615 						out1c(' ');
616 					}
617 					for (p = vp->text ; *p != '=' ; p++)
618 						out1c(*p);
619 					if (values && !(vp->flags & VUNSET)) {
620 						out1c('=');
621 						out1qstr(p + 1);
622 					}
623 					out1c('\n');
624 				}
625 			}
626 		}
627 	}
628 	return 0;
629 }
630 
631 
632 /*
633  * The "local" command.
634  */
635 
636 int
637 localcmd(int argc __unused, char **argv __unused)
638 {
639 	char *name;
640 
641 	if (! in_function())
642 		error("Not in a function");
643 	while ((name = *argptr++) != NULL) {
644 		mklocal(name);
645 	}
646 	return 0;
647 }
648 
649 
650 /*
651  * Make a variable a local variable.  When a variable is made local, it's
652  * value and flags are saved in a localvar structure.  The saved values
653  * will be restored when the shell function returns.  We handle the name
654  * "-" as a special case.
655  */
656 
657 void
658 mklocal(char *name)
659 {
660 	struct localvar *lvp;
661 	struct var **vpp;
662 	struct var *vp;
663 
664 	INTOFF;
665 	lvp = ckmalloc(sizeof (struct localvar));
666 	if (name[0] == '-' && name[1] == '\0') {
667 		lvp->text = ckmalloc(sizeof optlist);
668 		memcpy(lvp->text, optlist, sizeof optlist);
669 		vp = NULL;
670 	} else {
671 		vpp = hashvar(name);
672 		for (vp = *vpp ; vp && ! varequal(vp->text, name) ; vp = vp->next);
673 		if (vp == NULL) {
674 			if (strchr(name, '='))
675 				setvareq(savestr(name), VSTRFIXED);
676 			else
677 				setvar(name, NULL, VSTRFIXED);
678 			vp = *vpp;	/* the new variable */
679 			lvp->text = NULL;
680 			lvp->flags = VUNSET;
681 		} else {
682 			lvp->text = vp->text;
683 			lvp->flags = vp->flags;
684 			vp->flags |= VSTRFIXED|VTEXTFIXED;
685 			if (strchr(name, '='))
686 				setvareq(savestr(name), 0);
687 		}
688 	}
689 	lvp->vp = vp;
690 	lvp->next = localvars;
691 	localvars = lvp;
692 	INTON;
693 }
694 
695 
696 /*
697  * Called after a function returns.
698  */
699 
700 void
701 poplocalvars(void)
702 {
703 	struct localvar *lvp;
704 	struct var *vp;
705 
706 	while ((lvp = localvars) != NULL) {
707 		localvars = lvp->next;
708 		vp = lvp->vp;
709 		if (vp == NULL) {	/* $- saved */
710 			memcpy(optlist, lvp->text, sizeof optlist);
711 			ckfree(lvp->text);
712 		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
713 			(void)unsetvar(vp->text);
714 		} else {
715 			if ((vp->flags & VTEXTFIXED) == 0)
716 				ckfree(vp->text);
717 			vp->flags = lvp->flags;
718 			vp->text = lvp->text;
719 		}
720 		ckfree(lvp);
721 	}
722 }
723 
724 
725 int
726 setvarcmd(int argc, char **argv)
727 {
728 	if (argc <= 2)
729 		return unsetcmd(argc, argv);
730 	else if (argc == 3)
731 		setvar(argv[1], argv[2], 0);
732 	else
733 		error("List assignment not implemented");
734 	return 0;
735 }
736 
737 
738 /*
739  * The unset builtin command.  We unset the function before we unset the
740  * variable to allow a function to be unset when there is a readonly variable
741  * with the same name.
742  */
743 
744 int
745 unsetcmd(int argc __unused, char **argv __unused)
746 {
747 	char **ap;
748 	int i;
749 	int flg_func = 0;
750 	int flg_var = 0;
751 	int ret = 0;
752 
753 	while ((i = nextopt("vf")) != '\0') {
754 		if (i == 'f')
755 			flg_func = 1;
756 		else
757 			flg_var = 1;
758 	}
759 	if (flg_func == 0 && flg_var == 0)
760 		flg_var = 1;
761 
762 	for (ap = argptr; *ap ; ap++) {
763 		if (flg_func)
764 			ret |= unsetfunc(*ap);
765 		if (flg_var)
766 			ret |= unsetvar(*ap);
767 	}
768 	return ret;
769 }
770 
771 
772 /*
773  * Unset the specified variable.
774  */
775 
776 int
777 unsetvar(char *s)
778 {
779 	struct var **vpp;
780 	struct var *vp;
781 
782 	vpp = hashvar(s);
783 	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
784 		if (varequal(vp->text, s)) {
785 			if (vp->flags & VREADONLY)
786 				return (1);
787 			INTOFF;
788 			if (*(strchr(vp->text, '=') + 1) != '\0')
789 				setvar(s, nullstr, 0);
790 			if ((vp->flags & VEXPORT) && localevar(vp->text)) {
791 				unsetenv(s);
792 				setlocale(LC_ALL, "");
793 			}
794 			vp->flags &= ~VEXPORT;
795 			vp->flags |= VUNSET;
796 			if ((vp->flags & VSTRFIXED) == 0) {
797 				if ((vp->flags & VTEXTFIXED) == 0)
798 					ckfree(vp->text);
799 				*vpp = vp->next;
800 				ckfree(vp);
801 			}
802 			INTON;
803 			return (0);
804 		}
805 	}
806 
807 	return (0);
808 }
809 
810 
811 
812 /*
813  * Find the appropriate entry in the hash table from the name.
814  */
815 
816 STATIC struct var **
817 hashvar(char *p)
818 {
819 	unsigned int hashval;
820 
821 	hashval = ((unsigned char) *p) << 4;
822 	while (*p && *p != '=')
823 		hashval += (unsigned char) *p++;
824 	return &vartab[hashval % VTABSIZE];
825 }
826 
827 
828 
829 /*
830  * Returns true if the two strings specify the same varable.  The first
831  * variable name is terminated by '='; the second may be terminated by
832  * either '=' or '\0'.
833  */
834 
835 STATIC int
836 varequal(char *p, char *q)
837 {
838 	while (*p == *q++) {
839 		if (*p++ == '=')
840 			return 1;
841 	}
842 	if (*p == '=' && *(q - 1) == '\0')
843 		return 1;
844 	return 0;
845 }
846