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var.c revision 1.31 
      1 /*	$NetBSD: var.c,v 1.31 2002/11/25 12:13:03 agc 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 1.31 2002/11/25 12:13:03 agc 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)(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(const char *);
    137 STATIC int varequal(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(void)
    166 {
    167 	const struct varinit *ip;
    168 	struct var *vp;
    169 	struct var **vpp;
    170 
    171 	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
    172 		if ((vp->flags & VEXPORT) == 0) {
    173 			vpp = hashvar(ip->text);
    174 			vp->next = *vpp;
    175 			*vpp = vp;
    176 			vp->text = strdup(ip->text);
    177 			vp->flags = ip->flags;
    178 			vp->func = ip->func;
    179 		}
    180 	}
    181 	/*
    182 	 * PS1 depends on uid
    183 	 */
    184 	if ((vps1.flags & VEXPORT) == 0) {
    185 		vpp = hashvar("PS1=");
    186 		vps1.next = *vpp;
    187 		*vpp = &vps1;
    188 		vps1.text = strdup(geteuid() ? "PS1=$ " : "PS1=# ");
    189 		vps1.flags = VSTRFIXED|VTEXTFIXED;
    190 	}
    191 }
    192 
    193 /*
    194  * Safe version of setvar, returns 1 on success 0 on failure.
    195  */
    196 
    197 int
    198 setvarsafe(const char *name, const char *val, int flags)
    199 {
    200 	struct jmploc jmploc;
    201 	struct jmploc *volatile savehandler = handler;
    202 	int err = 0;
    203 #ifdef __GNUC__
    204 	(void) &err;
    205 #endif
    206 
    207 	if (setjmp(jmploc.loc))
    208 		err = 1;
    209 	else {
    210 		handler = &jmploc;
    211 		setvar(name, val, flags);
    212 	}
    213 	handler = savehandler;
    214 	return err;
    215 }
    216 
    217 /*
    218  * Set the value of a variable.  The flags argument is ored with the
    219  * flags of the variable.  If val is NULL, the variable is unset.
    220  */
    221 
    222 void
    223 setvar(const char *name, const char *val, int flags)
    224 {
    225 	const char *p;
    226 	const char *q;
    227 	char *d;
    228 	int len;
    229 	int namelen;
    230 	char *nameeq;
    231 	int isbad;
    232 
    233 	isbad = 0;
    234 	p = name;
    235 	if (! is_name(*p))
    236 		isbad = 1;
    237 	p++;
    238 	for (;;) {
    239 		if (! is_in_name(*p)) {
    240 			if (*p == '\0' || *p == '=')
    241 				break;
    242 			isbad = 1;
    243 		}
    244 		p++;
    245 	}
    246 	namelen = p - name;
    247 	if (isbad)
    248 		error("%.*s: bad variable name", namelen, name);
    249 	len = namelen + 2;		/* 2 is space for '=' and '\0' */
    250 	if (val == NULL) {
    251 		flags |= VUNSET;
    252 	} else {
    253 		len += strlen(val);
    254 	}
    255 	d = nameeq = ckmalloc(len);
    256 	q = name;
    257 	while (--namelen >= 0)
    258 		*d++ = *q++;
    259 	*d++ = '=';
    260 	*d = '\0';
    261 	if (val)
    262 		scopy(val, d);
    263 	setvareq(nameeq, flags);
    264 }
    265 
    266 
    267 
    268 /*
    269  * Same as setvar except that the variable and value are passed in
    270  * the first argument as name=value.  Since the first argument will
    271  * be actually stored in the table, it should not be a string that
    272  * will go away.
    273  */
    274 
    275 void
    276 setvareq(char *s, int flags)
    277 {
    278 	struct var *vp, **vpp;
    279 
    280 	if (aflag)
    281 		flags |= VEXPORT;
    282 	vpp = hashvar(s);
    283 	for (vp = *vpp ; vp ; vp = vp->next) {
    284 		if (varequal(s, vp->text)) {
    285 			if (vp->flags & VREADONLY) {
    286 				size_t len = strchr(s, '=') - s;
    287 				error("%.*s: is read only", len, s);
    288 			}
    289 			if (flags & VNOSET)
    290 				return;
    291 			INTOFF;
    292 
    293 			if (vp->func && (flags & VNOFUNC) == 0)
    294 				(*vp->func)(strchr(s, '=') + 1);
    295 
    296 			if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
    297 				ckfree(vp->text);
    298 
    299 			vp->flags &= ~(VTEXTFIXED|VSTACK|VUNSET);
    300 			vp->flags |= flags;
    301 			vp->text = s;
    302 
    303 			/*
    304 			 * We could roll this to a function, to handle it as
    305 			 * a regular variable function callback, but why bother?
    306 			 */
    307 			if (vp == &vmpath || (vp == &vmail && ! mpathset()))
    308 				chkmail(1);
    309 			INTON;
    310 			return;
    311 		}
    312 	}
    313 	/* not found */
    314 	if (flags & VNOSET)
    315 		return;
    316 	vp = ckmalloc(sizeof (*vp));
    317 	vp->flags = flags;
    318 	vp->text = s;
    319 	vp->next = *vpp;
    320 	vp->func = NULL;
    321 	*vpp = vp;
    322 }
    323 
    324 
    325 
    326 /*
    327  * Process a linked list of variable assignments.
    328  */
    329 
    330 void
    331 listsetvar(struct strlist *list, int flags)
    332 {
    333 	struct strlist *lp;
    334 
    335 	INTOFF;
    336 	for (lp = list ; lp ; lp = lp->next) {
    337 		setvareq(savestr(lp->text), flags);
    338 	}
    339 	INTON;
    340 }
    341 
    342 
    343 
    344 /*
    345  * Find the value of a variable.  Returns NULL if not set.
    346  */
    347 
    348 char *
    349 lookupvar(const char *name)
    350 {
    351 	struct var *v;
    352 
    353 	for (v = *hashvar(name) ; v ; v = v->next) {
    354 		if (varequal(v->text, name)) {
    355 			if (v->flags & VUNSET)
    356 				return NULL;
    357 			return strchr(v->text, '=') + 1;
    358 		}
    359 	}
    360 	return NULL;
    361 }
    362 
    363 
    364 
    365 /*
    366  * Search the environment of a builtin command.  If the second argument
    367  * is nonzero, return the value of a variable even if it hasn't been
    368  * exported.
    369  */
    370 
    371 char *
    372 bltinlookup(const char *name, int doall)
    373 {
    374 	struct strlist *sp;
    375 	struct var *v;
    376 
    377 	for (sp = cmdenviron ; sp ; sp = sp->next) {
    378 		if (varequal(sp->text, name))
    379 			return strchr(sp->text, '=') + 1;
    380 	}
    381 	for (v = *hashvar(name) ; v ; v = v->next) {
    382 		if (varequal(v->text, name)) {
    383 			if ((v->flags & VUNSET)
    384 			 || (!doall && (v->flags & VEXPORT) == 0))
    385 				return NULL;
    386 			return strchr(v->text, '=') + 1;
    387 		}
    388 	}
    389 	return NULL;
    390 }
    391 
    392 
    393 
    394 /*
    395  * Generate a list of exported variables.  This routine is used to construct
    396  * the third argument to execve when executing a program.
    397  */
    398 
    399 char **
    400 environment(void)
    401 {
    402 	int nenv;
    403 	struct var **vpp;
    404 	struct var *vp;
    405 	char **env;
    406 	char **ep;
    407 
    408 	nenv = 0;
    409 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    410 		for (vp = *vpp ; vp ; vp = vp->next)
    411 			if (vp->flags & VEXPORT)
    412 				nenv++;
    413 	}
    414 	ep = env = stalloc((nenv + 1) * sizeof *env);
    415 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    416 		for (vp = *vpp ; vp ; vp = vp->next)
    417 			if (vp->flags & VEXPORT)
    418 				*ep++ = vp->text;
    419 	}
    420 	*ep = NULL;
    421 	return env;
    422 }
    423 
    424 
    425 /*
    426  * Called when a shell procedure is invoked to clear out nonexported
    427  * variables.  It is also necessary to reallocate variables of with
    428  * VSTACK set since these are currently allocated on the stack.
    429  */
    430 
    431 #ifdef mkinit
    432 void shprocvar(void);
    433 
    434 SHELLPROC {
    435 	shprocvar();
    436 }
    437 #endif
    438 
    439 void
    440 shprocvar(void)
    441 {
    442 	struct var **vpp;
    443 	struct var *vp, **prev;
    444 
    445 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    446 		for (prev = vpp ; (vp = *prev) != NULL ; ) {
    447 			if ((vp->flags & VEXPORT) == 0) {
    448 				*prev = vp->next;
    449 				if ((vp->flags & VTEXTFIXED) == 0)
    450 					ckfree(vp->text);
    451 				if ((vp->flags & VSTRFIXED) == 0)
    452 					ckfree(vp);
    453 			} else {
    454 				if (vp->flags & VSTACK) {
    455 					vp->text = savestr(vp->text);
    456 					vp->flags &=~ VSTACK;
    457 				}
    458 				prev = &vp->next;
    459 			}
    460 		}
    461 	}
    462 	initvar();
    463 }
    464 
    465 
    466 
    467 /*
    468  * Command to list all variables which are set.  Currently this command
    469  * is invoked from the set command when the set command is called without
    470  * any variables.
    471  */
    472 
    473 void
    474 print_quoted(const char *p)
    475 {
    476 	const char *q;
    477 
    478 	if (strcspn(p, "|&;<>()$`\\\"' \t\n*?[]#~=%") == strlen(p)) {
    479 		out1fmt("%s", p);
    480 		return;
    481 	}
    482 	while (*p) {
    483 		if (*p == '\'') {
    484 			out1fmt("\\'");
    485 			p++;
    486 			continue;
    487 		}
    488 		q = index(p, '\'');
    489 		if (!q) {
    490 			out1fmt("'%s'", p );
    491 			return;
    492 		}
    493 		out1fmt("'%.*s'", (int)(q - p), p );
    494 		p = q;
    495 	}
    496 }
    497 
    498 static int
    499 sort_var(const void *v_v1, const void *v_v2)
    500 {
    501 	const struct var * const *v1 = v_v1;
    502 	const struct var * const *v2 = v_v2;
    503 
    504 	/* XXX Will anyone notice we include the '=' of the shorter name? */
    505 	return strcoll((*v1)->text, (*v2)->text);
    506 }
    507 
    508 /*
    509  * POSIX requires that 'set' (but not export or readonly) output the
    510  * variables in lexicographic order - by the locale's collating order (sigh).
    511  * Maybe we could keep them in an ordered balanced binary tree
    512  * instead of hashed lists.
    513  * For now just roll 'em through qsort for printing...
    514  */
    515 
    516 int
    517 showvars(const char *name, int flag, int show_value)
    518 {
    519 	struct var **vpp;
    520 	struct var *vp;
    521 	const char *p;
    522 
    523 	static struct var **list;	/* static in case we are interrupted */
    524 	static int list_len;
    525 	int count = 0;
    526 
    527 	if (!list) {
    528 		list_len = 32;
    529 		list = ckmalloc(list_len * sizeof *list);
    530 	}
    531 
    532 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    533 		for (vp = *vpp ; vp ; vp = vp->next) {
    534 			if (flag && !(vp->flags & flag))
    535 				continue;
    536 			if (vp->flags & VUNSET && !(show_value & 2))
    537 				continue;
    538 			if (count >= list_len) {
    539 				list = ckrealloc(list,
    540 					(list_len << 1) * sizeof *list);
    541 				list_len <<= 1;
    542 			}
    543 			list[count++] = vp;
    544 		}
    545 	}
    546 
    547 	qsort(list, count, sizeof *list, sort_var);
    548 
    549 	for (vpp = list; count--; vpp++) {
    550 		vp = *vpp;
    551 		if (name)
    552 			out1fmt("%s ", name);
    553 		for (p = vp->text ; *p != '=' ; p++)
    554 			out1c(*p);
    555 		if (!(vp->flags & VUNSET) && show_value) {
    556 			out1fmt("=");
    557 			print_quoted(++p);
    558 		}
    559 		out1c('\n');
    560 	}
    561 	return 0;
    562 }
    563 
    564 
    565 
    566 /*
    567  * The export and readonly commands.
    568  */
    569 
    570 int
    571 exportcmd(int argc, char **argv)
    572 {
    573 	struct var **vpp;
    574 	struct var *vp;
    575 	char *name;
    576 	const char *p;
    577 	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
    578 	int pflag;
    579 
    580 	pflag = nextopt("p") == 'p' ? 3 : 0;
    581 	if (argc <= 1 || pflag) {
    582 		showvars( pflag ? argv[0] : 0, flag, pflag );
    583 		return 0;
    584 	}
    585 
    586 	while ((name = *argptr++) != NULL) {
    587 		if ((p = strchr(name, '=')) != NULL) {
    588 			p++;
    589 		} else {
    590 			vpp = hashvar(name);
    591 			for (vp = *vpp ; vp ; vp = vp->next) {
    592 				if (varequal(vp->text, name)) {
    593 					vp->flags |= flag;
    594 					goto found;
    595 				}
    596 			}
    597 		}
    598 		setvar(name, p, flag);
    599 found:;
    600 	}
    601 	return 0;
    602 }
    603 
    604 
    605 /*
    606  * The "local" command.
    607  */
    608 
    609 int
    610 localcmd(int argc, char **argv)
    611 {
    612 	char *name;
    613 
    614 	if (! in_function())
    615 		error("Not in a function");
    616 	while ((name = *argptr++) != NULL) {
    617 		mklocal(name, 0);
    618 	}
    619 	return 0;
    620 }
    621 
    622 
    623 /*
    624  * Make a variable a local variable.  When a variable is made local, it's
    625  * value and flags are saved in a localvar structure.  The saved values
    626  * will be restored when the shell function returns.  We handle the name
    627  * "-" as a special case.
    628  */
    629 
    630 void
    631 mklocal(char *name, int flags)
    632 {
    633 	struct localvar *lvp;
    634 	struct var **vpp;
    635 	struct var *vp;
    636 
    637 	INTOFF;
    638 	lvp = ckmalloc(sizeof (struct localvar));
    639 	if (name[0] == '-' && name[1] == '\0') {
    640 		char *p;
    641 		p = ckmalloc(sizeof_optlist);
    642 		lvp->text = memcpy(p, optlist, sizeof_optlist);
    643 		vp = NULL;
    644 	} else {
    645 		vpp = hashvar(name);
    646 		for (vp = *vpp ; vp && ! varequal(vp->text, name) ; vp = vp->next);
    647 		if (vp == NULL) {
    648 			if (strchr(name, '='))
    649 				setvareq(savestr(name), VSTRFIXED|flags);
    650 			else
    651 				setvar(name, NULL, VSTRFIXED|flags);
    652 			vp = *vpp;	/* the new variable */
    653 			lvp->text = NULL;
    654 			lvp->flags = VUNSET;
    655 		} else {
    656 			lvp->text = vp->text;
    657 			lvp->flags = vp->flags;
    658 			vp->flags |= VSTRFIXED|VTEXTFIXED;
    659 			if (strchr(name, '='))
    660 				setvareq(savestr(name), flags);
    661 		}
    662 	}
    663 	lvp->vp = vp;
    664 	lvp->next = localvars;
    665 	localvars = lvp;
    666 	INTON;
    667 }
    668 
    669 
    670 /*
    671  * Called after a function returns.
    672  */
    673 
    674 void
    675 poplocalvars(void)
    676 {
    677 	struct localvar *lvp;
    678 	struct var *vp;
    679 
    680 	while ((lvp = localvars) != NULL) {
    681 		localvars = lvp->next;
    682 		vp = lvp->vp;
    683 		if (vp == NULL) {	/* $- saved */
    684 			memcpy(optlist, lvp->text, sizeof_optlist);
    685 			ckfree(lvp->text);
    686 		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
    687 			(void)unsetvar(vp->text, 0);
    688 		} else {
    689 			if ((vp->flags & VTEXTFIXED) == 0)
    690 				ckfree(vp->text);
    691 			vp->flags = lvp->flags;
    692 			vp->text = lvp->text;
    693 		}
    694 		ckfree(lvp);
    695 	}
    696 }
    697 
    698 
    699 int
    700 setvarcmd(int argc, char **argv)
    701 {
    702 	if (argc <= 2)
    703 		return unsetcmd(argc, argv);
    704 	else if (argc == 3)
    705 		setvar(argv[1], argv[2], 0);
    706 	else
    707 		error("List assignment not implemented");
    708 	return 0;
    709 }
    710 
    711 
    712 /*
    713  * The unset builtin command.  We unset the function before we unset the
    714  * variable to allow a function to be unset when there is a readonly variable
    715  * with the same name.
    716  */
    717 
    718 int
    719 unsetcmd(int argc, char **argv)
    720 {
    721 	char **ap;
    722 	int i;
    723 	int flg_func = 0;
    724 	int flg_var = 0;
    725 	int ret = 0;
    726 
    727 	while ((i = nextopt("evf")) != '\0') {
    728 		if (i == 'f')
    729 			flg_func = 1;
    730 		else
    731 			flg_var = i;
    732 	}
    733 	if (flg_func == 0 && flg_var == 0)
    734 		flg_var = 1;
    735 
    736 	for (ap = argptr; *ap ; ap++) {
    737 		if (flg_func)
    738 			ret |= unsetfunc(*ap);
    739 		if (flg_var)
    740 			ret |= unsetvar(*ap, flg_var == 'e');
    741 	}
    742 	return ret;
    743 }
    744 
    745 
    746 /*
    747  * Unset the specified variable.
    748  */
    749 
    750 int
    751 unsetvar(const char *s, int unexport)
    752 {
    753 	struct var **vpp;
    754 	struct var *vp;
    755 
    756 	vpp = hashvar(s);
    757 	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
    758 		if (varequal(vp->text, s)) {
    759 			if (vp->flags & VREADONLY)
    760 				return (1);
    761 			INTOFF;
    762 			if (unexport) {
    763 				vp->flags &= ~VEXPORT;
    764 			} else {
    765 				if (*(strchr(vp->text, '=') + 1) != '\0')
    766 					setvar(s, nullstr, 0);
    767 				vp->flags &= ~VEXPORT;
    768 				vp->flags |= VUNSET;
    769 				if ((vp->flags & VSTRFIXED) == 0) {
    770 					if ((vp->flags & VTEXTFIXED) == 0)
    771 						ckfree(vp->text);
    772 					*vpp = vp->next;
    773 					ckfree(vp);
    774 				}
    775 			}
    776 			INTON;
    777 			return (0);
    778 		}
    779 	}
    780 
    781 	return (1);
    782 }
    783 
    784 
    785 
    786 /*
    787  * Find the appropriate entry in the hash table from the name.
    788  */
    789 
    790 STATIC struct var **
    791 hashvar(const char *p)
    792 {
    793 	unsigned int hashval;
    794 
    795 	hashval = ((unsigned char) *p) << 4;
    796 	while (*p && *p != '=')
    797 		hashval += (unsigned char) *p++;
    798 	return &vartab[hashval % VTABSIZE];
    799 }
    800 
    801 
    802 
    803 /*
    804  * Returns true if the two strings specify the same varable.  The first
    805  * variable name is terminated by '='; the second may be terminated by
    806  * either '=' or '\0'.
    807  */
    808 
    809 STATIC int
    810 varequal(const char *p, const char *q)
    811 {
    812 	while (*p == *q++) {
    813 		if (*p++ == '=')
    814 			return 1;
    815 	}
    816 	if (*p == '=' && *(q - 1) == '\0')
    817 		return 1;
    818 	return 0;
    819 }
    820