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var.c revision 1.6 
      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[] = "@(#)var.c	8.1 (Berkeley) 5/31/93";
     39 #endif /* not lint */
     40 
     41 /*
     42  * Shell variables.
     43  */
     44 
     45 #include "shell.h"
     46 #include "output.h"
     47 #include "expand.h"
     48 #include "nodes.h"	/* for other headers */
     49 #include "eval.h"	/* defines cmdenviron */
     50 #include "exec.h"
     51 #include "syntax.h"
     52 #include "options.h"
     53 #include "mail.h"
     54 #include "var.h"
     55 #include "memalloc.h"
     56 #include "error.h"
     57 #include "mystring.h"
     58 #include <unistd.h>
     59 
     60 
     61 #define VTABSIZE 39
     62 
     63 
     64 struct varinit {
     65 	struct var *var;
     66 	int flags;
     67 	char *text;
     68 };
     69 
     70 
     71 #if ATTY
     72 struct var vatty;
     73 #endif
     74 struct var vhistsize;
     75 struct var vifs;
     76 struct var vmail;
     77 struct var vmpath;
     78 struct var vpath;
     79 struct var vps1;
     80 struct var vps2;
     81 struct var vvers;
     82 #if ATTY
     83 struct var vterm;
     84 #endif
     85 
     86 const struct varinit varinit[] = {
     87 #if ATTY
     88 	{&vatty,	VSTRFIXED|VTEXTFIXED|VUNSET,	"ATTY="},
     89 #endif
     90 	{&vhistsize,	VSTRFIXED|VTEXTFIXED|VUNSET,	"HISTSIZE="},
     91 	{&vifs,	VSTRFIXED|VTEXTFIXED,		"IFS= \t\n"},
     92 	{&vmail,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAIL="},
     93 	{&vmpath,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAILPATH="},
     94 	{&vpath,	VSTRFIXED|VTEXTFIXED,		"PATH=:/bin:/usr/bin"},
     95 	/*
     96 	 * vps1 depends on uid
     97 	 */
     98 	{&vps2,	VSTRFIXED|VTEXTFIXED,		"PS2=> "},
     99 #if ATTY
    100 	{&vterm,	VSTRFIXED|VTEXTFIXED|VUNSET,	"TERM="},
    101 #endif
    102 	{NULL,	0,				NULL}
    103 };
    104 
    105 struct var *vartab[VTABSIZE];
    106 
    107 STATIC int unsetvar __P((char *));
    108 STATIC struct var **hashvar __P((char *));
    109 STATIC int varequal __P((char *, char *));
    110 
    111 /*
    112  * Initialize the varable symbol tables and import the environment
    113  */
    114 
    115 #ifdef mkinit
    116 INCLUDE "var.h"
    117 INIT {
    118 	char **envp;
    119 	extern char **environ;
    120 
    121 	initvar();
    122 	for (envp = environ ; *envp ; envp++) {
    123 		if (strchr(*envp, '=')) {
    124 			setvareq(*envp, VEXPORT|VTEXTFIXED);
    125 		}
    126 	}
    127 }
    128 #endif
    129 
    130 
    131 /*
    132  * This routine initializes the builtin variables.  It is called when the
    133  * shell is initialized and again when a shell procedure is spawned.
    134  */
    135 
    136 void
    137 initvar() {
    138 	const struct varinit *ip;
    139 	struct var *vp;
    140 	struct var **vpp;
    141 
    142 	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
    143 		if ((vp->flags & VEXPORT) == 0) {
    144 			vpp = hashvar(ip->text);
    145 			vp->next = *vpp;
    146 			*vpp = vp;
    147 			vp->text = ip->text;
    148 			vp->flags = ip->flags;
    149 		}
    150 	}
    151 	/*
    152 	 * PS1 depends on uid
    153 	 */
    154 	if ((vps1.flags & VEXPORT) == 0) {
    155 		vpp = hashvar("PS1=");
    156 		vps1.next = *vpp;
    157 		*vpp = &vps1;
    158 		vps1.text = geteuid() ? "PS1=$ " : "PS1=# ";
    159 		vps1.flags = VSTRFIXED|VTEXTFIXED;
    160 	}
    161 }
    162 
    163 /*
    164  * Set the value of a variable.  The flags argument is ored with the
    165  * flags of the variable.  If val is NULL, the variable is unset.
    166  */
    167 
    168 void
    169 setvar(name, val, flags)
    170 	char *name, *val;
    171 	{
    172 	char *p, *q;
    173 	int len;
    174 	int namelen;
    175 	char *nameeq;
    176 	int isbad;
    177 
    178 	isbad = 0;
    179 	p = name;
    180 	if (! is_name(*p++))
    181 		isbad = 1;
    182 	for (;;) {
    183 		if (! is_in_name(*p)) {
    184 			if (*p == '\0' || *p == '=')
    185 				break;
    186 			isbad = 1;
    187 		}
    188 		p++;
    189 	}
    190 	namelen = p - name;
    191 	if (isbad)
    192 		error("%.*s: bad variable name", namelen, name);
    193 	len = namelen + 2;		/* 2 is space for '=' and '\0' */
    194 	if (val == NULL) {
    195 		flags |= VUNSET;
    196 	} else {
    197 		len += strlen(val);
    198 	}
    199 	p = nameeq = ckmalloc(len);
    200 	q = name;
    201 	while (--namelen >= 0)
    202 		*p++ = *q++;
    203 	*p++ = '=';
    204 	*p = '\0';
    205 	if (val)
    206 		scopy(val, p);
    207 	setvareq(nameeq, flags);
    208 }
    209 
    210 
    211 
    212 /*
    213  * Same as setvar except that the variable and value are passed in
    214  * the first argument as name=value.  Since the first argument will
    215  * be actually stored in the table, it should not be a string that
    216  * will go away.
    217  */
    218 
    219 void
    220 setvareq(s, flags)
    221 	char *s;
    222 	{
    223 	struct var *vp, **vpp;
    224 
    225 	vpp = hashvar(s);
    226 	for (vp = *vpp ; vp ; vp = vp->next) {
    227 		if (varequal(s, vp->text)) {
    228 			if (vp->flags & VREADONLY) {
    229 				int len = strchr(s, '=') - s;
    230 				error("%.*s: is read only", len, s);
    231 			}
    232 			INTOFF;
    233 			if (vp == &vpath)
    234 				changepath(s + 5);	/* 5 = strlen("PATH=") */
    235 			if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
    236 				ckfree(vp->text);
    237 			vp->flags &=~ (VTEXTFIXED|VSTACK|VUNSET);
    238 			vp->flags |= flags;
    239 			vp->text = s;
    240 			if (vp == &vmpath || (vp == &vmail && ! mpathset()))
    241 				chkmail(1);
    242 			if (vp == &vhistsize)
    243 				sethistsize();
    244 			INTON;
    245 			return;
    246 		}
    247 	}
    248 	/* not found */
    249 	vp = ckmalloc(sizeof (*vp));
    250 	vp->flags = flags;
    251 	vp->text = s;
    252 	vp->next = *vpp;
    253 	*vpp = vp;
    254 }
    255 
    256 
    257 
    258 /*
    259  * Process a linked list of variable assignments.
    260  */
    261 
    262 void
    263 listsetvar(list)
    264 	struct strlist *list;
    265 	{
    266 	struct strlist *lp;
    267 
    268 	INTOFF;
    269 	for (lp = list ; lp ; lp = lp->next) {
    270 		setvareq(savestr(lp->text), 0);
    271 	}
    272 	INTON;
    273 }
    274 
    275 
    276 
    277 /*
    278  * Find the value of a variable.  Returns NULL if not set.
    279  */
    280 
    281 char *
    282 lookupvar(name)
    283 	char *name;
    284 	{
    285 	struct var *v;
    286 
    287 	for (v = *hashvar(name) ; v ; v = v->next) {
    288 		if (varequal(v->text, name)) {
    289 			if (v->flags & VUNSET)
    290 				return NULL;
    291 			return strchr(v->text, '=') + 1;
    292 		}
    293 	}
    294 	return NULL;
    295 }
    296 
    297 
    298 
    299 /*
    300  * Search the environment of a builtin command.  If the second argument
    301  * is nonzero, return the value of a variable even if it hasn't been
    302  * exported.
    303  */
    304 
    305 char *
    306 bltinlookup(name, doall)
    307 	char *name;
    308 	{
    309 	struct strlist *sp;
    310 	struct var *v;
    311 
    312 	for (sp = cmdenviron ; sp ; sp = sp->next) {
    313 		if (varequal(sp->text, name))
    314 			return strchr(sp->text, '=') + 1;
    315 	}
    316 	for (v = *hashvar(name) ; v ; v = v->next) {
    317 		if (varequal(v->text, name)) {
    318 			if (v->flags & VUNSET
    319 			 || ! doall && (v->flags & VEXPORT) == 0)
    320 				return NULL;
    321 			return strchr(v->text, '=') + 1;
    322 		}
    323 	}
    324 	return NULL;
    325 }
    326 
    327 
    328 
    329 /*
    330  * Generate a list of exported variables.  This routine is used to construct
    331  * the third argument to execve when executing a program.
    332  */
    333 
    334 char **
    335 environment() {
    336 	int nenv;
    337 	struct var **vpp;
    338 	struct var *vp;
    339 	char **env, **ep;
    340 
    341 	nenv = 0;
    342 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    343 		for (vp = *vpp ; vp ; vp = vp->next)
    344 			if (vp->flags & VEXPORT)
    345 				nenv++;
    346 	}
    347 	ep = env = stalloc((nenv + 1) * sizeof *env);
    348 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    349 		for (vp = *vpp ; vp ; vp = vp->next)
    350 			if (vp->flags & VEXPORT)
    351 				*ep++ = vp->text;
    352 	}
    353 	*ep = NULL;
    354 	return env;
    355 }
    356 
    357 
    358 /*
    359  * Called when a shell procedure is invoked to clear out nonexported
    360  * variables.  It is also necessary to reallocate variables of with
    361  * VSTACK set since these are currently allocated on the stack.
    362  */
    363 
    364 #ifdef mkinit
    365 MKINIT void shprocvar();
    366 
    367 SHELLPROC {
    368 	shprocvar();
    369 }
    370 #endif
    371 
    372 void
    373 shprocvar() {
    374 	struct var **vpp;
    375 	struct var *vp, **prev;
    376 
    377 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    378 		for (prev = vpp ; (vp = *prev) != NULL ; ) {
    379 			if ((vp->flags & VEXPORT) == 0) {
    380 				*prev = vp->next;
    381 				if ((vp->flags & VTEXTFIXED) == 0)
    382 					ckfree(vp->text);
    383 				if ((vp->flags & VSTRFIXED) == 0)
    384 					ckfree(vp);
    385 			} else {
    386 				if (vp->flags & VSTACK) {
    387 					vp->text = savestr(vp->text);
    388 					vp->flags &=~ VSTACK;
    389 				}
    390 				prev = &vp->next;
    391 			}
    392 		}
    393 	}
    394 	initvar();
    395 }
    396 
    397 
    398 
    399 /*
    400  * Command to list all variables which are set.  Currently this command
    401  * is invoked from the set command when the set command is called without
    402  * any variables.
    403  */
    404 
    405 int
    406 showvarscmd(argc, argv)  char **argv; {
    407 	struct var **vpp;
    408 	struct var *vp;
    409 
    410 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    411 		for (vp = *vpp ; vp ; vp = vp->next) {
    412 			if ((vp->flags & VUNSET) == 0)
    413 				out1fmt("%s\n", vp->text);
    414 		}
    415 	}
    416 	return 0;
    417 }
    418 
    419 
    420 
    421 /*
    422  * The export and readonly commands.
    423  */
    424 
    425 int
    426 exportcmd(argc, argv)  char **argv; {
    427 	struct var **vpp;
    428 	struct var *vp;
    429 	char *name;
    430 	char *p;
    431 	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
    432 
    433 	listsetvar(cmdenviron);
    434 	if (argc > 1) {
    435 		while ((name = *argptr++) != NULL) {
    436 			if ((p = strchr(name, '=')) != NULL) {
    437 				p++;
    438 			} else {
    439 				vpp = hashvar(name);
    440 				for (vp = *vpp ; vp ; vp = vp->next) {
    441 					if (varequal(vp->text, name)) {
    442 						vp->flags |= flag;
    443 						goto found;
    444 					}
    445 				}
    446 			}
    447 			setvar(name, p, flag);
    448 found:;
    449 		}
    450 	} else {
    451 		for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    452 			for (vp = *vpp ; vp ; vp = vp->next) {
    453 				if (vp->flags & flag) {
    454 					for (p = vp->text ; *p != '=' ; p++)
    455 						out1c(*p);
    456 					out1c('\n');
    457 				}
    458 			}
    459 		}
    460 	}
    461 	return 0;
    462 }
    463 
    464 
    465 /*
    466  * The "local" command.
    467  */
    468 
    469 localcmd(argc, argv)  char **argv; {
    470 	char *name;
    471 
    472 	if (! in_function())
    473 		error("Not in a function");
    474 	while ((name = *argptr++) != NULL) {
    475 		mklocal(name);
    476 	}
    477 	return 0;
    478 }
    479 
    480 
    481 /*
    482  * Make a variable a local variable.  When a variable is made local, it's
    483  * value and flags are saved in a localvar structure.  The saved values
    484  * will be restored when the shell function returns.  We handle the name
    485  * "-" as a special case.
    486  */
    487 
    488 void
    489 mklocal(name)
    490 	char *name;
    491 	{
    492 	struct localvar *lvp;
    493 	struct var **vpp;
    494 	struct var *vp;
    495 
    496 	INTOFF;
    497 	lvp = ckmalloc(sizeof (struct localvar));
    498 	if (name[0] == '-' && name[1] == '\0') {
    499 		lvp->text = ckmalloc(sizeof optlist);
    500 		bcopy(optlist, lvp->text, sizeof optlist);
    501 		vp = NULL;
    502 	} else {
    503 		vpp = hashvar(name);
    504 		for (vp = *vpp ; vp && ! varequal(vp->text, name) ; vp = vp->next);
    505 		if (vp == NULL) {
    506 			if (strchr(name, '='))
    507 				setvareq(savestr(name), VSTRFIXED);
    508 			else
    509 				setvar(name, NULL, VSTRFIXED);
    510 			vp = *vpp;	/* the new variable */
    511 			lvp->text = NULL;
    512 			lvp->flags = VUNSET;
    513 		} else {
    514 			lvp->text = vp->text;
    515 			lvp->flags = vp->flags;
    516 			vp->flags |= VSTRFIXED|VTEXTFIXED;
    517 			if (strchr(name, '='))
    518 				setvareq(savestr(name), 0);
    519 		}
    520 	}
    521 	lvp->vp = vp;
    522 	lvp->next = localvars;
    523 	localvars = lvp;
    524 	INTON;
    525 }
    526 
    527 
    528 /*
    529  * Called after a function returns.
    530  */
    531 
    532 void
    533 poplocalvars() {
    534 	struct localvar *lvp;
    535 	struct var *vp;
    536 
    537 	while ((lvp = localvars) != NULL) {
    538 		localvars = lvp->next;
    539 		vp = lvp->vp;
    540 		if (vp == NULL) {	/* $- saved */
    541 			bcopy(lvp->text, optlist, sizeof optlist);
    542 			ckfree(lvp->text);
    543 		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
    544 			(void)unsetvar(vp->text);
    545 		} else {
    546 			if ((vp->flags & VTEXTFIXED) == 0)
    547 				ckfree(vp->text);
    548 			vp->flags = lvp->flags;
    549 			vp->text = lvp->text;
    550 		}
    551 		ckfree(lvp);
    552 	}
    553 }
    554 
    555 
    556 setvarcmd(argc, argv)  char **argv; {
    557 	if (argc <= 2)
    558 		return unsetcmd(argc, argv);
    559 	else if (argc == 3)
    560 		setvar(argv[1], argv[2], 0);
    561 	else
    562 		error("List assignment not implemented");
    563 	return 0;
    564 }
    565 
    566 
    567 /*
    568  * The unset builtin command.  We unset the function before we unset the
    569  * variable to allow a function to be unset when there is a readonly variable
    570  * with the same name.
    571  */
    572 
    573 unsetcmd(argc, argv)  char **argv; {
    574 	char **ap;
    575 	int i;
    576 	int flg_func = 0;
    577 	int flg_var = 0;
    578 	int ret = 0;
    579 
    580 	while ((i = nextopt("vf")) != '\0') {
    581 		if (i == 'f')
    582 			flg_func = 1;
    583 		else
    584 			flg_var = 1;
    585 	}
    586 	if (flg_func == 0 && flg_var == 0)
    587 		flg_var = 1;
    588 
    589 	for (ap = argptr; *ap ; ap++) {
    590 		if (flg_func)
    591 			ret |= unsetfunc(*ap);
    592 		if (flg_var)
    593 			ret |= unsetvar(*ap);
    594 	}
    595 	return ret;
    596 }
    597 
    598 
    599 /*
    600  * Unset the specified variable.
    601  */
    602 
    603 STATIC int
    604 unsetvar(s)
    605 	char *s;
    606 	{
    607 	struct var **vpp;
    608 	struct var *vp;
    609 
    610 	vpp = hashvar(s);
    611 	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
    612 		if (varequal(vp->text, s)) {
    613 			if (vp->flags & VREADONLY)
    614 				return (1);
    615 			INTOFF;
    616 			if (*(strchr(vp->text, '=') + 1) != '\0')
    617 				setvar(s, nullstr, 0);
    618 			vp->flags &=~ VEXPORT;
    619 			vp->flags |= VUNSET;
    620 			if ((vp->flags & VSTRFIXED) == 0) {
    621 				if ((vp->flags & VTEXTFIXED) == 0)
    622 					ckfree(vp->text);
    623 				*vpp = vp->next;
    624 				ckfree(vp);
    625 			}
    626 			INTON;
    627 			return (0);
    628 		}
    629 	}
    630 
    631 	return (1);
    632 }
    633 
    634 
    635 
    636 /*
    637  * Find the appropriate entry in the hash table from the name.
    638  */
    639 
    640 STATIC struct var **
    641 hashvar(p)
    642 	register char *p;
    643 	{
    644 	unsigned int hashval;
    645 
    646 	hashval = *p << 4;
    647 	while (*p && *p != '=')
    648 		hashval += *p++;
    649 	return &vartab[hashval % VTABSIZE];
    650 }
    651 
    652 
    653 
    654 /*
    655  * Returns true if the two strings specify the same varable.  The first
    656  * variable name is terminated by '='; the second may be terminated by
    657  * either '=' or '\0'.
    658  */
    659 
    660 STATIC int
    661 varequal(p, q)
    662 	register char *p, *q;
    663 	{
    664 	while (*p == *q++) {
    665 		if (*p++ == '=')
    666 			return 1;
    667 	}
    668 	if (*p == '=' && *(q - 1) == '\0')
    669 		return 1;
    670 	return 0;
    671 }
    672