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var.c revision 1.10 
      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
     38 /*static char sccsid[] = "from: @(#)var.c	8.1 (Berkeley) 5/31/93";*/
     39 static char *rcsid = "$Id: var.c,v 1.10 1994/12/05 19:07:58 cgd Exp $";
     40 #endif /* not lint */
     41 
     42 /*
     43  * Shell variables.
     44  */
     45 
     46 #include <unistd.h>
     47 
     48 #include "shell.h"
     49 #include "output.h"
     50 #include "expand.h"
     51 #include "nodes.h"	/* for other headers */
     52 #include "eval.h"	/* defines cmdenviron */
     53 #include "exec.h"
     54 #include "syntax.h"
     55 #include "options.h"
     56 #include "mail.h"
     57 #include "var.h"
     58 #include "memalloc.h"
     59 #include "error.h"
     60 #include "mystring.h"
     61 #include "extern.h"
     62 
     63 
     64 #define VTABSIZE 39
     65 
     66 
     67 struct varinit {
     68 	struct var *var;
     69 	int flags;
     70 	char *text;
     71 };
     72 
     73 
     74 #if ATTY
     75 struct var vatty;
     76 #endif
     77 #ifndef NO_HISTORY
     78 struct var vhistsize;
     79 #endif
     80 struct var vifs;
     81 struct var vmail;
     82 struct var vmpath;
     83 struct var vpath;
     84 struct var vps1;
     85 struct var vps2;
     86 struct var vvers;
     87 #if ATTY
     88 struct var vterm;
     89 #endif
     90 
     91 const struct varinit varinit[] = {
     92 #if ATTY
     93 	{&vatty,	VSTRFIXED|VTEXTFIXED|VUNSET,	"ATTY="},
     94 #endif
     95 #ifndef NO_HISTORY
     96 	{&vhistsize,	VSTRFIXED|VTEXTFIXED|VUNSET,	"HISTSIZE="},
     97 #endif
     98 	{&vifs,	VSTRFIXED|VTEXTFIXED,		"IFS= \t\n"},
     99 	{&vmail,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAIL="},
    100 	{&vmpath,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAILPATH="},
    101 	{&vpath,	VSTRFIXED|VTEXTFIXED,		"PATH=:/bin:/usr/bin"},
    102 	/*
    103 	 * vps1 depends on uid
    104 	 */
    105 	{&vps2,	VSTRFIXED|VTEXTFIXED,		"PS2=> "},
    106 #if ATTY
    107 	{&vterm,	VSTRFIXED|VTEXTFIXED|VUNSET,	"TERM="},
    108 #endif
    109 	{NULL,	0,				NULL}
    110 };
    111 
    112 struct var *vartab[VTABSIZE];
    113 
    114 STATIC int unsetvar __P((char *));
    115 STATIC struct var **hashvar __P((char *));
    116 STATIC int varequal __P((char *, char *));
    117 
    118 /*
    119  * Initialize the varable symbol tables and import the environment
    120  */
    121 
    122 #ifdef mkinit
    123 INCLUDE "var.h"
    124 INIT {
    125 	char **envp;
    126 	extern char **environ;
    127 
    128 	initvar();
    129 	for (envp = environ ; *envp ; envp++) {
    130 		if (strchr(*envp, '=')) {
    131 			setvareq(*envp, VEXPORT|VTEXTFIXED);
    132 		}
    133 	}
    134 }
    135 #endif
    136 
    137 
    138 /*
    139  * This routine initializes the builtin variables.  It is called when the
    140  * shell is initialized and again when a shell procedure is spawned.
    141  */
    142 
    143 void
    144 initvar() {
    145 	const struct varinit *ip;
    146 	struct var *vp;
    147 	struct var **vpp;
    148 
    149 	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
    150 		if ((vp->flags & VEXPORT) == 0) {
    151 			vpp = hashvar(ip->text);
    152 			vp->next = *vpp;
    153 			*vpp = vp;
    154 			vp->text = ip->text;
    155 			vp->flags = ip->flags;
    156 		}
    157 	}
    158 	/*
    159 	 * PS1 depends on uid
    160 	 */
    161 	if ((vps1.flags & VEXPORT) == 0) {
    162 		vpp = hashvar("PS1=");
    163 		vps1.next = *vpp;
    164 		*vpp = &vps1;
    165 		vps1.text = geteuid() ? "PS1=$ " : "PS1=# ";
    166 		vps1.flags = VSTRFIXED|VTEXTFIXED;
    167 	}
    168 }
    169 
    170 /*
    171  * Set the value of a variable.  The flags argument is ored with the
    172  * flags of the variable.  If val is NULL, the variable is unset.
    173  */
    174 
    175 void
    176 setvar(name, val, flags)
    177 	char *name, *val;
    178 	int flags;
    179 {
    180 	char *p, *q;
    181 	int len;
    182 	int namelen;
    183 	char *nameeq;
    184 	int isbad;
    185 
    186 	isbad = 0;
    187 	p = name;
    188 	if (! is_name(*p++))
    189 		isbad = 1;
    190 	for (;;) {
    191 		if (! is_in_name(*p)) {
    192 			if (*p == '\0' || *p == '=')
    193 				break;
    194 			isbad = 1;
    195 		}
    196 		p++;
    197 	}
    198 	namelen = p - name;
    199 	if (isbad)
    200 		error("%.*s: bad variable name", namelen, name);
    201 	len = namelen + 2;		/* 2 is space for '=' and '\0' */
    202 	if (val == NULL) {
    203 		flags |= VUNSET;
    204 	} else {
    205 		len += strlen(val);
    206 	}
    207 	p = nameeq = ckmalloc(len);
    208 	q = name;
    209 	while (--namelen >= 0)
    210 		*p++ = *q++;
    211 	*p++ = '=';
    212 	*p = '\0';
    213 	if (val)
    214 		scopy(val, p);
    215 	setvareq(nameeq, flags);
    216 }
    217 
    218 
    219 
    220 /*
    221  * Same as setvar except that the variable and value are passed in
    222  * the first argument as name=value.  Since the first argument will
    223  * be actually stored in the table, it should not be a string that
    224  * will go away.
    225  */
    226 
    227 void
    228 setvareq(s, flags)
    229 	char *s;
    230 	int flags;
    231 {
    232 	struct var *vp, **vpp;
    233 
    234 	vpp = hashvar(s);
    235 	for (vp = *vpp ; vp ; vp = vp->next) {
    236 		if (varequal(s, vp->text)) {
    237 			if (vp->flags & VREADONLY) {
    238 				int len = strchr(s, '=') - s;
    239 				error("%.*s: is read only", len, s);
    240 			}
    241 			INTOFF;
    242 			if (vp == &vpath)
    243 				changepath(s + 5);	/* 5 = strlen("PATH=") */
    244 			if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
    245 				ckfree(vp->text);
    246 			vp->flags &=~ (VTEXTFIXED|VSTACK|VUNSET);
    247 			vp->flags |= flags;
    248 			vp->text = s;
    249 			if (vp == &vmpath || (vp == &vmail && ! mpathset()))
    250 				chkmail(1);
    251 #ifndef NO_HISTORY
    252 			if (vp == &vhistsize)
    253 				sethistsize();
    254 #endif
    255 			INTON;
    256 			return;
    257 		}
    258 	}
    259 	/* not found */
    260 	vp = ckmalloc(sizeof (*vp));
    261 	vp->flags = flags;
    262 	vp->text = s;
    263 	vp->next = *vpp;
    264 	*vpp = vp;
    265 }
    266 
    267 
    268 
    269 /*
    270  * Process a linked list of variable assignments.
    271  */
    272 
    273 void
    274 listsetvar(list)
    275 	struct strlist *list;
    276 	{
    277 	struct strlist *lp;
    278 
    279 	INTOFF;
    280 	for (lp = list ; lp ; lp = lp->next) {
    281 		setvareq(savestr(lp->text), 0);
    282 	}
    283 	INTON;
    284 }
    285 
    286 
    287 
    288 /*
    289  * Find the value of a variable.  Returns NULL if not set.
    290  */
    291 
    292 char *
    293 lookupvar(name)
    294 	char *name;
    295 	{
    296 	struct var *v;
    297 
    298 	for (v = *hashvar(name) ; v ; v = v->next) {
    299 		if (varequal(v->text, name)) {
    300 			if (v->flags & VUNSET)
    301 				return NULL;
    302 			return strchr(v->text, '=') + 1;
    303 		}
    304 	}
    305 	return NULL;
    306 }
    307 
    308 
    309 
    310 /*
    311  * Search the environment of a builtin command.  If the second argument
    312  * is nonzero, return the value of a variable even if it hasn't been
    313  * exported.
    314  */
    315 
    316 char *
    317 bltinlookup(name, doall)
    318 	char *name;
    319 	int doall;
    320 {
    321 	struct strlist *sp;
    322 	struct var *v;
    323 
    324 	for (sp = cmdenviron ; sp ; sp = sp->next) {
    325 		if (varequal(sp->text, name))
    326 			return strchr(sp->text, '=') + 1;
    327 	}
    328 	for (v = *hashvar(name) ; v ; v = v->next) {
    329 		if (varequal(v->text, name)) {
    330 			if (v->flags & VUNSET
    331 			 || ! doall && (v->flags & VEXPORT) == 0)
    332 				return NULL;
    333 			return strchr(v->text, '=') + 1;
    334 		}
    335 	}
    336 	return NULL;
    337 }
    338 
    339 
    340 
    341 /*
    342  * Generate a list of exported variables.  This routine is used to construct
    343  * the third argument to execve when executing a program.
    344  */
    345 
    346 char **
    347 environment() {
    348 	int nenv;
    349 	struct var **vpp;
    350 	struct var *vp;
    351 	char **env, **ep;
    352 
    353 	nenv = 0;
    354 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    355 		for (vp = *vpp ; vp ; vp = vp->next)
    356 			if (vp->flags & VEXPORT)
    357 				nenv++;
    358 	}
    359 	ep = env = stalloc((nenv + 1) * sizeof *env);
    360 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    361 		for (vp = *vpp ; vp ; vp = vp->next)
    362 			if (vp->flags & VEXPORT)
    363 				*ep++ = vp->text;
    364 	}
    365 	*ep = NULL;
    366 	return env;
    367 }
    368 
    369 
    370 /*
    371  * Called when a shell procedure is invoked to clear out nonexported
    372  * variables.  It is also necessary to reallocate variables of with
    373  * VSTACK set since these are currently allocated on the stack.
    374  */
    375 
    376 #ifdef mkinit
    377 MKINIT void shprocvar();
    378 
    379 SHELLPROC {
    380 	shprocvar();
    381 }
    382 #endif
    383 
    384 void
    385 shprocvar() {
    386 	struct var **vpp;
    387 	struct var *vp, **prev;
    388 
    389 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    390 		for (prev = vpp ; (vp = *prev) != NULL ; ) {
    391 			if ((vp->flags & VEXPORT) == 0) {
    392 				*prev = vp->next;
    393 				if ((vp->flags & VTEXTFIXED) == 0)
    394 					ckfree(vp->text);
    395 				if ((vp->flags & VSTRFIXED) == 0)
    396 					ckfree(vp);
    397 			} else {
    398 				if (vp->flags & VSTACK) {
    399 					vp->text = savestr(vp->text);
    400 					vp->flags &=~ VSTACK;
    401 				}
    402 				prev = &vp->next;
    403 			}
    404 		}
    405 	}
    406 	initvar();
    407 }
    408 
    409 
    410 
    411 /*
    412  * Command to list all variables which are set.  Currently this command
    413  * is invoked from the set command when the set command is called without
    414  * any variables.
    415  */
    416 
    417 int
    418 showvarscmd(argc, argv)
    419 	int argc;
    420 	char **argv;
    421 {
    422 	struct var **vpp;
    423 	struct var *vp;
    424 
    425 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    426 		for (vp = *vpp ; vp ; vp = vp->next) {
    427 			if ((vp->flags & VUNSET) == 0)
    428 				out1fmt("%s\n", vp->text);
    429 		}
    430 	}
    431 	return 0;
    432 }
    433 
    434 
    435 
    436 /*
    437  * The export and readonly commands.
    438  */
    439 
    440 int
    441 exportcmd(argc, argv)
    442 	int argc;
    443 	char **argv;
    444 {
    445 	struct var **vpp;
    446 	struct var *vp;
    447 	char *name;
    448 	char *p;
    449 	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
    450 
    451 	listsetvar(cmdenviron);
    452 	if (argc > 1) {
    453 		while ((name = *argptr++) != NULL) {
    454 			if ((p = strchr(name, '=')) != NULL) {
    455 				p++;
    456 			} else {
    457 				vpp = hashvar(name);
    458 				for (vp = *vpp ; vp ; vp = vp->next) {
    459 					if (varequal(vp->text, name)) {
    460 						vp->flags |= flag;
    461 						goto found;
    462 					}
    463 				}
    464 			}
    465 			setvar(name, p, flag);
    466 found:;
    467 		}
    468 	} else {
    469 		for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    470 			for (vp = *vpp ; vp ; vp = vp->next) {
    471 				if (vp->flags & flag) {
    472 					for (p = vp->text ; *p != '=' ; p++)
    473 						out1c(*p);
    474 					out1c('\n');
    475 				}
    476 			}
    477 		}
    478 	}
    479 	return 0;
    480 }
    481 
    482 
    483 /*
    484  * The "local" command.
    485  */
    486 
    487 int
    488 localcmd(argc, argv)
    489 	int argc;
    490 	char **argv;
    491 {
    492 	char *name;
    493 
    494 	if (! in_function())
    495 		error("Not in a function");
    496 	while ((name = *argptr++) != NULL) {
    497 		mklocal(name);
    498 	}
    499 	return 0;
    500 }
    501 
    502 
    503 /*
    504  * Make a variable a local variable.  When a variable is made local, it's
    505  * value and flags are saved in a localvar structure.  The saved values
    506  * will be restored when the shell function returns.  We handle the name
    507  * "-" as a special case.
    508  */
    509 
    510 void
    511 mklocal(name)
    512 	char *name;
    513 	{
    514 	struct localvar *lvp;
    515 	struct var **vpp;
    516 	struct var *vp;
    517 
    518 	INTOFF;
    519 	lvp = ckmalloc(sizeof (struct localvar));
    520 	if (name[0] == '-' && name[1] == '\0') {
    521 		lvp->text = ckmalloc(sizeof optlist);
    522 		memcpy(lvp->text, optlist, sizeof optlist);
    523 		vp = NULL;
    524 	} else {
    525 		vpp = hashvar(name);
    526 		for (vp = *vpp ; vp && ! varequal(vp->text, name) ; vp = vp->next);
    527 		if (vp == NULL) {
    528 			if (strchr(name, '='))
    529 				setvareq(savestr(name), VSTRFIXED);
    530 			else
    531 				setvar(name, NULL, VSTRFIXED);
    532 			vp = *vpp;	/* the new variable */
    533 			lvp->text = NULL;
    534 			lvp->flags = VUNSET;
    535 		} else {
    536 			lvp->text = vp->text;
    537 			lvp->flags = vp->flags;
    538 			vp->flags |= VSTRFIXED|VTEXTFIXED;
    539 			if (strchr(name, '='))
    540 				setvareq(savestr(name), 0);
    541 		}
    542 	}
    543 	lvp->vp = vp;
    544 	lvp->next = localvars;
    545 	localvars = lvp;
    546 	INTON;
    547 }
    548 
    549 
    550 /*
    551  * Called after a function returns.
    552  */
    553 
    554 void
    555 poplocalvars() {
    556 	struct localvar *lvp;
    557 	struct var *vp;
    558 
    559 	while ((lvp = localvars) != NULL) {
    560 		localvars = lvp->next;
    561 		vp = lvp->vp;
    562 		if (vp == NULL) {	/* $- saved */
    563 			memcpy(optlist, lvp->text, sizeof optlist);
    564 			ckfree(lvp->text);
    565 		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
    566 			(void)unsetvar(vp->text);
    567 		} else {
    568 			if ((vp->flags & VTEXTFIXED) == 0)
    569 				ckfree(vp->text);
    570 			vp->flags = lvp->flags;
    571 			vp->text = lvp->text;
    572 		}
    573 		ckfree(lvp);
    574 	}
    575 }
    576 
    577 
    578 int
    579 setvarcmd(argc, argv)
    580 	int argc;
    581 	char **argv;
    582 {
    583 	if (argc <= 2)
    584 		return unsetcmd(argc, argv);
    585 	else if (argc == 3)
    586 		setvar(argv[1], argv[2], 0);
    587 	else
    588 		error("List assignment not implemented");
    589 	return 0;
    590 }
    591 
    592 
    593 /*
    594  * The unset builtin command.  We unset the function before we unset the
    595  * variable to allow a function to be unset when there is a readonly variable
    596  * with the same name.
    597  */
    598 
    599 int
    600 unsetcmd(argc, argv)
    601 	int argc;
    602 	char **argv;
    603 {
    604 	char **ap;
    605 	int i;
    606 	int flg_func = 0;
    607 	int flg_var = 0;
    608 	int ret = 0;
    609 
    610 	while ((i = nextopt("vf")) != '\0') {
    611 		if (i == 'f')
    612 			flg_func = 1;
    613 		else
    614 			flg_var = 1;
    615 	}
    616 	if (flg_func == 0 && flg_var == 0)
    617 		flg_var = 1;
    618 
    619 	for (ap = argptr; *ap ; ap++) {
    620 		if (flg_func)
    621 			ret |= unsetfunc(*ap);
    622 		if (flg_var)
    623 			ret |= unsetvar(*ap);
    624 	}
    625 	return ret;
    626 }
    627 
    628 
    629 /*
    630  * Unset the specified variable.
    631  */
    632 
    633 STATIC int
    634 unsetvar(s)
    635 	char *s;
    636 	{
    637 	struct var **vpp;
    638 	struct var *vp;
    639 
    640 	vpp = hashvar(s);
    641 	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
    642 		if (varequal(vp->text, s)) {
    643 			if (vp->flags & VREADONLY)
    644 				return (1);
    645 			INTOFF;
    646 			if (*(strchr(vp->text, '=') + 1) != '\0')
    647 				setvar(s, nullstr, 0);
    648 			vp->flags &=~ VEXPORT;
    649 			vp->flags |= VUNSET;
    650 			if ((vp->flags & VSTRFIXED) == 0) {
    651 				if ((vp->flags & VTEXTFIXED) == 0)
    652 					ckfree(vp->text);
    653 				*vpp = vp->next;
    654 				ckfree(vp);
    655 			}
    656 			INTON;
    657 			return (0);
    658 		}
    659 	}
    660 
    661 	return (1);
    662 }
    663 
    664 
    665 
    666 /*
    667  * Find the appropriate entry in the hash table from the name.
    668  */
    669 
    670 STATIC struct var **
    671 hashvar(p)
    672 	register char *p;
    673 	{
    674 	unsigned int hashval;
    675 
    676 	hashval = *p << 4;
    677 	while (*p && *p != '=')
    678 		hashval += *p++;
    679 	return &vartab[hashval % VTABSIZE];
    680 }
    681 
    682 
    683 
    684 /*
    685  * Returns true if the two strings specify the same varable.  The first
    686  * variable name is terminated by '='; the second may be terminated by
    687  * either '=' or '\0'.
    688  */
    689 
    690 STATIC int
    691 varequal(p, q)
    692 	register char *p, *q;
    693 	{
    694 	while (*p == *q++) {
    695 		if (*p++ == '=')
    696 			return 1;
    697 	}
    698 	if (*p == '=' && *(q - 1) == '\0')
    699 		return 1;
    700 	return 0;
    701 }
    702