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var.c revision 1.9 
      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 1.9 1994/09/23 11:28:46 mycroft Exp $";
     40 #endif /* not lint */
     41 
     42 /*
     43  * Shell variables.
     44  */
     45 
     46 #include "shell.h"
     47 #include "output.h"
     48 #include "expand.h"
     49 #include "nodes.h"	/* for other headers */
     50 #include "eval.h"	/* defines cmdenviron */
     51 #include "exec.h"
     52 #include "syntax.h"
     53 #include "options.h"
     54 #include "mail.h"
     55 #include "var.h"
     56 #include "memalloc.h"
     57 #include "error.h"
     58 #include "mystring.h"
     59 #include <unistd.h>
     60 
     61 
     62 #define VTABSIZE 39
     63 
     64 
     65 struct varinit {
     66 	struct var *var;
     67 	int flags;
     68 	char *text;
     69 };
     70 
     71 
     72 #if ATTY
     73 struct var vatty;
     74 #endif
     75 #ifndef NO_HISTORY
     76 struct var vhistsize;
     77 #endif
     78 struct var vifs;
     79 struct var vmail;
     80 struct var vmpath;
     81 struct var vpath;
     82 struct var vps1;
     83 struct var vps2;
     84 struct var vvers;
     85 #if ATTY
     86 struct var vterm;
     87 #endif
     88 
     89 const struct varinit varinit[] = {
     90 #if ATTY
     91 	{&vatty,	VSTRFIXED|VTEXTFIXED|VUNSET,	"ATTY="},
     92 #endif
     93 #ifndef NO_HISTORY
     94 	{&vhistsize,	VSTRFIXED|VTEXTFIXED|VUNSET,	"HISTSIZE="},
     95 #endif
     96 	{&vifs,	VSTRFIXED|VTEXTFIXED,		"IFS= \t\n"},
     97 	{&vmail,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAIL="},
     98 	{&vmpath,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAILPATH="},
     99 	{&vpath,	VSTRFIXED|VTEXTFIXED,		"PATH=:/bin:/usr/bin"},
    100 	/*
    101 	 * vps1 depends on uid
    102 	 */
    103 	{&vps2,	VSTRFIXED|VTEXTFIXED,		"PS2=> "},
    104 #if ATTY
    105 	{&vterm,	VSTRFIXED|VTEXTFIXED|VUNSET,	"TERM="},
    106 #endif
    107 	{NULL,	0,				NULL}
    108 };
    109 
    110 struct var *vartab[VTABSIZE];
    111 
    112 STATIC int unsetvar __P((char *));
    113 STATIC struct var **hashvar __P((char *));
    114 STATIC int varequal __P((char *, char *));
    115 
    116 /*
    117  * Initialize the varable symbol tables and import the environment
    118  */
    119 
    120 #ifdef mkinit
    121 INCLUDE "var.h"
    122 INIT {
    123 	char **envp;
    124 	extern char **environ;
    125 
    126 	initvar();
    127 	for (envp = environ ; *envp ; envp++) {
    128 		if (strchr(*envp, '=')) {
    129 			setvareq(*envp, VEXPORT|VTEXTFIXED);
    130 		}
    131 	}
    132 }
    133 #endif
    134 
    135 
    136 /*
    137  * This routine initializes the builtin variables.  It is called when the
    138  * shell is initialized and again when a shell procedure is spawned.
    139  */
    140 
    141 void
    142 initvar() {
    143 	const struct varinit *ip;
    144 	struct var *vp;
    145 	struct var **vpp;
    146 
    147 	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
    148 		if ((vp->flags & VEXPORT) == 0) {
    149 			vpp = hashvar(ip->text);
    150 			vp->next = *vpp;
    151 			*vpp = vp;
    152 			vp->text = ip->text;
    153 			vp->flags = ip->flags;
    154 		}
    155 	}
    156 	/*
    157 	 * PS1 depends on uid
    158 	 */
    159 	if ((vps1.flags & VEXPORT) == 0) {
    160 		vpp = hashvar("PS1=");
    161 		vps1.next = *vpp;
    162 		*vpp = &vps1;
    163 		vps1.text = geteuid() ? "PS1=$ " : "PS1=# ";
    164 		vps1.flags = VSTRFIXED|VTEXTFIXED;
    165 	}
    166 }
    167 
    168 /*
    169  * Set the value of a variable.  The flags argument is ored with the
    170  * flags of the variable.  If val is NULL, the variable is unset.
    171  */
    172 
    173 void
    174 setvar(name, val, flags)
    175 	char *name, *val;
    176 	{
    177 	char *p, *q;
    178 	int len;
    179 	int namelen;
    180 	char *nameeq;
    181 	int isbad;
    182 
    183 	isbad = 0;
    184 	p = name;
    185 	if (! is_name(*p++))
    186 		isbad = 1;
    187 	for (;;) {
    188 		if (! is_in_name(*p)) {
    189 			if (*p == '\0' || *p == '=')
    190 				break;
    191 			isbad = 1;
    192 		}
    193 		p++;
    194 	}
    195 	namelen = p - name;
    196 	if (isbad)
    197 		error("%.*s: bad variable name", namelen, name);
    198 	len = namelen + 2;		/* 2 is space for '=' and '\0' */
    199 	if (val == NULL) {
    200 		flags |= VUNSET;
    201 	} else {
    202 		len += strlen(val);
    203 	}
    204 	p = nameeq = ckmalloc(len);
    205 	q = name;
    206 	while (--namelen >= 0)
    207 		*p++ = *q++;
    208 	*p++ = '=';
    209 	*p = '\0';
    210 	if (val)
    211 		scopy(val, p);
    212 	setvareq(nameeq, flags);
    213 }
    214 
    215 
    216 
    217 /*
    218  * Same as setvar except that the variable and value are passed in
    219  * the first argument as name=value.  Since the first argument will
    220  * be actually stored in the table, it should not be a string that
    221  * will go away.
    222  */
    223 
    224 void
    225 setvareq(s, flags)
    226 	char *s;
    227 	{
    228 	struct var *vp, **vpp;
    229 
    230 	vpp = hashvar(s);
    231 	for (vp = *vpp ; vp ; vp = vp->next) {
    232 		if (varequal(s, vp->text)) {
    233 			if (vp->flags & VREADONLY) {
    234 				int len = strchr(s, '=') - s;
    235 				error("%.*s: is read only", len, s);
    236 			}
    237 			INTOFF;
    238 			if (vp == &vpath)
    239 				changepath(s + 5);	/* 5 = strlen("PATH=") */
    240 			if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
    241 				ckfree(vp->text);
    242 			vp->flags &=~ (VTEXTFIXED|VSTACK|VUNSET);
    243 			vp->flags |= flags;
    244 			vp->text = s;
    245 			if (vp == &vmpath || (vp == &vmail && ! mpathset()))
    246 				chkmail(1);
    247 #ifndef NO_HISTORY
    248 			if (vp == &vhistsize)
    249 				sethistsize();
    250 #endif
    251 			INTON;
    252 			return;
    253 		}
    254 	}
    255 	/* not found */
    256 	vp = ckmalloc(sizeof (*vp));
    257 	vp->flags = flags;
    258 	vp->text = s;
    259 	vp->next = *vpp;
    260 	*vpp = vp;
    261 }
    262 
    263 
    264 
    265 /*
    266  * Process a linked list of variable assignments.
    267  */
    268 
    269 void
    270 listsetvar(list)
    271 	struct strlist *list;
    272 	{
    273 	struct strlist *lp;
    274 
    275 	INTOFF;
    276 	for (lp = list ; lp ; lp = lp->next) {
    277 		setvareq(savestr(lp->text), 0);
    278 	}
    279 	INTON;
    280 }
    281 
    282 
    283 
    284 /*
    285  * Find the value of a variable.  Returns NULL if not set.
    286  */
    287 
    288 char *
    289 lookupvar(name)
    290 	char *name;
    291 	{
    292 	struct var *v;
    293 
    294 	for (v = *hashvar(name) ; v ; v = v->next) {
    295 		if (varequal(v->text, name)) {
    296 			if (v->flags & VUNSET)
    297 				return NULL;
    298 			return strchr(v->text, '=') + 1;
    299 		}
    300 	}
    301 	return NULL;
    302 }
    303 
    304 
    305 
    306 /*
    307  * Search the environment of a builtin command.  If the second argument
    308  * is nonzero, return the value of a variable even if it hasn't been
    309  * exported.
    310  */
    311 
    312 char *
    313 bltinlookup(name, doall)
    314 	char *name;
    315 	{
    316 	struct strlist *sp;
    317 	struct var *v;
    318 
    319 	for (sp = cmdenviron ; sp ; sp = sp->next) {
    320 		if (varequal(sp->text, name))
    321 			return strchr(sp->text, '=') + 1;
    322 	}
    323 	for (v = *hashvar(name) ; v ; v = v->next) {
    324 		if (varequal(v->text, name)) {
    325 			if (v->flags & VUNSET
    326 			 || ! doall && (v->flags & VEXPORT) == 0)
    327 				return NULL;
    328 			return strchr(v->text, '=') + 1;
    329 		}
    330 	}
    331 	return NULL;
    332 }
    333 
    334 
    335 
    336 /*
    337  * Generate a list of exported variables.  This routine is used to construct
    338  * the third argument to execve when executing a program.
    339  */
    340 
    341 char **
    342 environment() {
    343 	int nenv;
    344 	struct var **vpp;
    345 	struct var *vp;
    346 	char **env, **ep;
    347 
    348 	nenv = 0;
    349 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    350 		for (vp = *vpp ; vp ; vp = vp->next)
    351 			if (vp->flags & VEXPORT)
    352 				nenv++;
    353 	}
    354 	ep = env = stalloc((nenv + 1) * sizeof *env);
    355 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    356 		for (vp = *vpp ; vp ; vp = vp->next)
    357 			if (vp->flags & VEXPORT)
    358 				*ep++ = vp->text;
    359 	}
    360 	*ep = NULL;
    361 	return env;
    362 }
    363 
    364 
    365 /*
    366  * Called when a shell procedure is invoked to clear out nonexported
    367  * variables.  It is also necessary to reallocate variables of with
    368  * VSTACK set since these are currently allocated on the stack.
    369  */
    370 
    371 #ifdef mkinit
    372 MKINIT void shprocvar();
    373 
    374 SHELLPROC {
    375 	shprocvar();
    376 }
    377 #endif
    378 
    379 void
    380 shprocvar() {
    381 	struct var **vpp;
    382 	struct var *vp, **prev;
    383 
    384 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    385 		for (prev = vpp ; (vp = *prev) != NULL ; ) {
    386 			if ((vp->flags & VEXPORT) == 0) {
    387 				*prev = vp->next;
    388 				if ((vp->flags & VTEXTFIXED) == 0)
    389 					ckfree(vp->text);
    390 				if ((vp->flags & VSTRFIXED) == 0)
    391 					ckfree(vp);
    392 			} else {
    393 				if (vp->flags & VSTACK) {
    394 					vp->text = savestr(vp->text);
    395 					vp->flags &=~ VSTACK;
    396 				}
    397 				prev = &vp->next;
    398 			}
    399 		}
    400 	}
    401 	initvar();
    402 }
    403 
    404 
    405 
    406 /*
    407  * Command to list all variables which are set.  Currently this command
    408  * is invoked from the set command when the set command is called without
    409  * any variables.
    410  */
    411 
    412 int
    413 showvarscmd(argc, argv)  char **argv; {
    414 	struct var **vpp;
    415 	struct var *vp;
    416 
    417 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    418 		for (vp = *vpp ; vp ; vp = vp->next) {
    419 			if ((vp->flags & VUNSET) == 0)
    420 				out1fmt("%s\n", vp->text);
    421 		}
    422 	}
    423 	return 0;
    424 }
    425 
    426 
    427 
    428 /*
    429  * The export and readonly commands.
    430  */
    431 
    432 int
    433 exportcmd(argc, argv)  char **argv; {
    434 	struct var **vpp;
    435 	struct var *vp;
    436 	char *name;
    437 	char *p;
    438 	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
    439 
    440 	listsetvar(cmdenviron);
    441 	if (argc > 1) {
    442 		while ((name = *argptr++) != NULL) {
    443 			if ((p = strchr(name, '=')) != NULL) {
    444 				p++;
    445 			} else {
    446 				vpp = hashvar(name);
    447 				for (vp = *vpp ; vp ; vp = vp->next) {
    448 					if (varequal(vp->text, name)) {
    449 						vp->flags |= flag;
    450 						goto found;
    451 					}
    452 				}
    453 			}
    454 			setvar(name, p, flag);
    455 found:;
    456 		}
    457 	} else {
    458 		for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    459 			for (vp = *vpp ; vp ; vp = vp->next) {
    460 				if (vp->flags & flag) {
    461 					for (p = vp->text ; *p != '=' ; p++)
    462 						out1c(*p);
    463 					out1c('\n');
    464 				}
    465 			}
    466 		}
    467 	}
    468 	return 0;
    469 }
    470 
    471 
    472 /*
    473  * The "local" command.
    474  */
    475 
    476 localcmd(argc, argv)  char **argv; {
    477 	char *name;
    478 
    479 	if (! in_function())
    480 		error("Not in a function");
    481 	while ((name = *argptr++) != NULL) {
    482 		mklocal(name);
    483 	}
    484 	return 0;
    485 }
    486 
    487 
    488 /*
    489  * Make a variable a local variable.  When a variable is made local, it's
    490  * value and flags are saved in a localvar structure.  The saved values
    491  * will be restored when the shell function returns.  We handle the name
    492  * "-" as a special case.
    493  */
    494 
    495 void
    496 mklocal(name)
    497 	char *name;
    498 	{
    499 	struct localvar *lvp;
    500 	struct var **vpp;
    501 	struct var *vp;
    502 
    503 	INTOFF;
    504 	lvp = ckmalloc(sizeof (struct localvar));
    505 	if (name[0] == '-' && name[1] == '\0') {
    506 		lvp->text = ckmalloc(sizeof optlist);
    507 		memcpy(lvp->text, optlist, sizeof optlist);
    508 		vp = NULL;
    509 	} else {
    510 		vpp = hashvar(name);
    511 		for (vp = *vpp ; vp && ! varequal(vp->text, name) ; vp = vp->next);
    512 		if (vp == NULL) {
    513 			if (strchr(name, '='))
    514 				setvareq(savestr(name), VSTRFIXED);
    515 			else
    516 				setvar(name, NULL, VSTRFIXED);
    517 			vp = *vpp;	/* the new variable */
    518 			lvp->text = NULL;
    519 			lvp->flags = VUNSET;
    520 		} else {
    521 			lvp->text = vp->text;
    522 			lvp->flags = vp->flags;
    523 			vp->flags |= VSTRFIXED|VTEXTFIXED;
    524 			if (strchr(name, '='))
    525 				setvareq(savestr(name), 0);
    526 		}
    527 	}
    528 	lvp->vp = vp;
    529 	lvp->next = localvars;
    530 	localvars = lvp;
    531 	INTON;
    532 }
    533 
    534 
    535 /*
    536  * Called after a function returns.
    537  */
    538 
    539 void
    540 poplocalvars() {
    541 	struct localvar *lvp;
    542 	struct var *vp;
    543 
    544 	while ((lvp = localvars) != NULL) {
    545 		localvars = lvp->next;
    546 		vp = lvp->vp;
    547 		if (vp == NULL) {	/* $- saved */
    548 			memcpy(optlist, lvp->text, sizeof optlist);
    549 			ckfree(lvp->text);
    550 		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
    551 			(void)unsetvar(vp->text);
    552 		} else {
    553 			if ((vp->flags & VTEXTFIXED) == 0)
    554 				ckfree(vp->text);
    555 			vp->flags = lvp->flags;
    556 			vp->text = lvp->text;
    557 		}
    558 		ckfree(lvp);
    559 	}
    560 }
    561 
    562 
    563 setvarcmd(argc, argv)  char **argv; {
    564 	if (argc <= 2)
    565 		return unsetcmd(argc, argv);
    566 	else if (argc == 3)
    567 		setvar(argv[1], argv[2], 0);
    568 	else
    569 		error("List assignment not implemented");
    570 	return 0;
    571 }
    572 
    573 
    574 /*
    575  * The unset builtin command.  We unset the function before we unset the
    576  * variable to allow a function to be unset when there is a readonly variable
    577  * with the same name.
    578  */
    579 
    580 unsetcmd(argc, argv)  char **argv; {
    581 	char **ap;
    582 	int i;
    583 	int flg_func = 0;
    584 	int flg_var = 0;
    585 	int ret = 0;
    586 
    587 	while ((i = nextopt("vf")) != '\0') {
    588 		if (i == 'f')
    589 			flg_func = 1;
    590 		else
    591 			flg_var = 1;
    592 	}
    593 	if (flg_func == 0 && flg_var == 0)
    594 		flg_var = 1;
    595 
    596 	for (ap = argptr; *ap ; ap++) {
    597 		if (flg_func)
    598 			ret |= unsetfunc(*ap);
    599 		if (flg_var)
    600 			ret |= unsetvar(*ap);
    601 	}
    602 	return ret;
    603 }
    604 
    605 
    606 /*
    607  * Unset the specified variable.
    608  */
    609 
    610 STATIC int
    611 unsetvar(s)
    612 	char *s;
    613 	{
    614 	struct var **vpp;
    615 	struct var *vp;
    616 
    617 	vpp = hashvar(s);
    618 	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
    619 		if (varequal(vp->text, s)) {
    620 			if (vp->flags & VREADONLY)
    621 				return (1);
    622 			INTOFF;
    623 			if (*(strchr(vp->text, '=') + 1) != '\0')
    624 				setvar(s, nullstr, 0);
    625 			vp->flags &=~ VEXPORT;
    626 			vp->flags |= VUNSET;
    627 			if ((vp->flags & VSTRFIXED) == 0) {
    628 				if ((vp->flags & VTEXTFIXED) == 0)
    629 					ckfree(vp->text);
    630 				*vpp = vp->next;
    631 				ckfree(vp);
    632 			}
    633 			INTON;
    634 			return (0);
    635 		}
    636 	}
    637 
    638 	return (1);
    639 }
    640 
    641 
    642 
    643 /*
    644  * Find the appropriate entry in the hash table from the name.
    645  */
    646 
    647 STATIC struct var **
    648 hashvar(p)
    649 	register char *p;
    650 	{
    651 	unsigned int hashval;
    652 
    653 	hashval = *p << 4;
    654 	while (*p && *p != '=')
    655 		hashval += *p++;
    656 	return &vartab[hashval % VTABSIZE];
    657 }
    658 
    659 
    660 
    661 /*
    662  * Returns true if the two strings specify the same varable.  The first
    663  * variable name is terminated by '='; the second may be terminated by
    664  * either '=' or '\0'.
    665  */
    666 
    667 STATIC int
    668 varequal(p, q)
    669 	register char *p, *q;
    670 	{
    671 	while (*p == *q++) {
    672 		if (*p++ == '=')
    673 			return 1;
    674 	}
    675 	if (*p == '=' && *(q - 1) == '\0')
    676 		return 1;
    677 	return 0;
    678 }
    679