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var.c revision 1.5 
      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 
     59 
     60 #define VTABSIZE 39
     61 
     62 
     63 struct varinit {
     64 	struct var *var;
     65 	int flags;
     66 	char *text;
     67 };
     68 
     69 
     70 #if ATTY
     71 struct var vatty;
     72 #endif
     73 struct var vhistsize;
     74 struct var vifs;
     75 struct var vmail;
     76 struct var vmpath;
     77 struct var vpath;
     78 struct var vps1;
     79 struct var vps2;
     80 struct var vvers;
     81 #if ATTY
     82 struct var vterm;
     83 #endif
     84 
     85 const struct varinit varinit[] = {
     86 #if ATTY
     87 	{&vatty,	VSTRFIXED|VTEXTFIXED|VUNSET,	"ATTY="},
     88 #endif
     89 	{&vhistsize,	VSTRFIXED|VTEXTFIXED|VUNSET,	"HISTSIZE="},
     90 	{&vifs,	VSTRFIXED|VTEXTFIXED,		"IFS= \t\n"},
     91 	{&vmail,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAIL="},
     92 	{&vmpath,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAILPATH="},
     93 	{&vpath,	VSTRFIXED|VTEXTFIXED,		"PATH=:/bin:/usr/bin"},
     94 	/*
     95 	 * vps1 depends on uid
     96 	 */
     97 	{&vps2,	VSTRFIXED|VTEXTFIXED,		"PS2=> "},
     98 #if ATTY
     99 	{&vterm,	VSTRFIXED|VTEXTFIXED|VUNSET,	"TERM="},
    100 #endif
    101 	{NULL,	0,				NULL}
    102 };
    103 
    104 struct var *vartab[VTABSIZE];
    105 
    106 STATIC int unsetvar __P((char *));
    107 STATIC struct var **hashvar __P((char *));
    108 STATIC int varequal __P((char *, char *));
    109 
    110 /*
    111  * Initialize the varable symbol tables and import the environment
    112  */
    113 
    114 #ifdef mkinit
    115 INCLUDE "var.h"
    116 INIT {
    117 	char **envp;
    118 	extern char **environ;
    119 
    120 	initvar();
    121 	for (envp = environ ; *envp ; envp++) {
    122 		if (strchr(*envp, '=')) {
    123 			setvareq(*envp, VEXPORT|VTEXTFIXED);
    124 		}
    125 	}
    126 }
    127 #endif
    128 
    129 
    130 /*
    131  * This routine initializes the builtin variables.  It is called when the
    132  * shell is initialized and again when a shell procedure is spawned.
    133  */
    134 
    135 void
    136 initvar() {
    137 	const struct varinit *ip;
    138 	struct var *vp;
    139 	struct var **vpp;
    140 
    141 	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
    142 		if ((vp->flags & VEXPORT) == 0) {
    143 			vpp = hashvar(ip->text);
    144 			vp->next = *vpp;
    145 			*vpp = vp;
    146 			vp->text = ip->text;
    147 			vp->flags = ip->flags;
    148 		}
    149 	}
    150 	/*
    151 	 * PS1 depends on uid
    152 	 */
    153 	if ((vps1.flags & VEXPORT) == 0) {
    154 		vpp = hashvar("PS1=");
    155 		vps1.next = *vpp;
    156 		*vpp = &vps1;
    157 		vps1.text = geteuid() ? "PS1=$ " : "PS1=# ";
    158 		vps1.flags = VSTRFIXED|VTEXTFIXED;
    159 	}
    160 }
    161 
    162 /*
    163  * Set the value of a variable.  The flags argument is ored with the
    164  * flags of the variable.  If val is NULL, the variable is unset.
    165  */
    166 
    167 void
    168 setvar(name, val, flags)
    169 	char *name, *val;
    170 	{
    171 	char *p, *q;
    172 	int len;
    173 	int namelen;
    174 	char *nameeq;
    175 	int isbad;
    176 
    177 	isbad = 0;
    178 	p = name;
    179 	if (! is_name(*p++))
    180 		isbad = 1;
    181 	for (;;) {
    182 		if (! is_in_name(*p)) {
    183 			if (*p == '\0' || *p == '=')
    184 				break;
    185 			isbad = 1;
    186 		}
    187 		p++;
    188 	}
    189 	namelen = p - name;
    190 	if (isbad)
    191 		error("%.*s: bad variable name", namelen, name);
    192 	len = namelen + 2;		/* 2 is space for '=' and '\0' */
    193 	if (val == NULL) {
    194 		flags |= VUNSET;
    195 	} else {
    196 		len += strlen(val);
    197 	}
    198 	p = nameeq = ckmalloc(len);
    199 	q = name;
    200 	while (--namelen >= 0)
    201 		*p++ = *q++;
    202 	*p++ = '=';
    203 	*p = '\0';
    204 	if (val)
    205 		scopy(val, p);
    206 	setvareq(nameeq, flags);
    207 }
    208 
    209 
    210 
    211 /*
    212  * Same as setvar except that the variable and value are passed in
    213  * the first argument as name=value.  Since the first argument will
    214  * be actually stored in the table, it should not be a string that
    215  * will go away.
    216  */
    217 
    218 void
    219 setvareq(s, flags)
    220 	char *s;
    221 	{
    222 	struct var *vp, **vpp;
    223 
    224 	vpp = hashvar(s);
    225 	for (vp = *vpp ; vp ; vp = vp->next) {
    226 		if (varequal(s, vp->text)) {
    227 			if (vp->flags & VREADONLY) {
    228 				int len = strchr(s, '=') - s;
    229 				error("%.*s: is read only", len, s);
    230 			}
    231 			INTOFF;
    232 			if (vp == &vpath)
    233 				changepath(s + 5);	/* 5 = strlen("PATH=") */
    234 			if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
    235 				ckfree(vp->text);
    236 			vp->flags &=~ (VTEXTFIXED|VSTACK|VUNSET);
    237 			vp->flags |= flags;
    238 			vp->text = s;
    239 			if (vp == &vmpath || (vp == &vmail && ! mpathset()))
    240 				chkmail(1);
    241 			if (vp == &vhistsize)
    242 				sethistsize();
    243 			INTON;
    244 			return;
    245 		}
    246 	}
    247 	/* not found */
    248 	vp = ckmalloc(sizeof (*vp));
    249 	vp->flags = flags;
    250 	vp->text = s;
    251 	vp->next = *vpp;
    252 	*vpp = vp;
    253 }
    254 
    255 
    256 
    257 /*
    258  * Process a linked list of variable assignments.
    259  */
    260 
    261 void
    262 listsetvar(list)
    263 	struct strlist *list;
    264 	{
    265 	struct strlist *lp;
    266 
    267 	INTOFF;
    268 	for (lp = list ; lp ; lp = lp->next) {
    269 		setvareq(savestr(lp->text), 0);
    270 	}
    271 	INTON;
    272 }
    273 
    274 
    275 
    276 /*
    277  * Find the value of a variable.  Returns NULL if not set.
    278  */
    279 
    280 char *
    281 lookupvar(name)
    282 	char *name;
    283 	{
    284 	struct var *v;
    285 
    286 	for (v = *hashvar(name) ; v ; v = v->next) {
    287 		if (varequal(v->text, name)) {
    288 			if (v->flags & VUNSET)
    289 				return NULL;
    290 			return strchr(v->text, '=') + 1;
    291 		}
    292 	}
    293 	return NULL;
    294 }
    295 
    296 
    297 
    298 /*
    299  * Search the environment of a builtin command.  If the second argument
    300  * is nonzero, return the value of a variable even if it hasn't been
    301  * exported.
    302  */
    303 
    304 char *
    305 bltinlookup(name, doall)
    306 	char *name;
    307 	{
    308 	struct strlist *sp;
    309 	struct var *v;
    310 
    311 	for (sp = cmdenviron ; sp ; sp = sp->next) {
    312 		if (varequal(sp->text, name))
    313 			return strchr(sp->text, '=') + 1;
    314 	}
    315 	for (v = *hashvar(name) ; v ; v = v->next) {
    316 		if (varequal(v->text, name)) {
    317 			if (v->flags & VUNSET
    318 			 || ! doall && (v->flags & VEXPORT) == 0)
    319 				return NULL;
    320 			return strchr(v->text, '=') + 1;
    321 		}
    322 	}
    323 	return NULL;
    324 }
    325 
    326 
    327 
    328 /*
    329  * Generate a list of exported variables.  This routine is used to construct
    330  * the third argument to execve when executing a program.
    331  */
    332 
    333 char **
    334 environment() {
    335 	int nenv;
    336 	struct var **vpp;
    337 	struct var *vp;
    338 	char **env, **ep;
    339 
    340 	nenv = 0;
    341 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    342 		for (vp = *vpp ; vp ; vp = vp->next)
    343 			if (vp->flags & VEXPORT)
    344 				nenv++;
    345 	}
    346 	ep = env = stalloc((nenv + 1) * sizeof *env);
    347 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    348 		for (vp = *vpp ; vp ; vp = vp->next)
    349 			if (vp->flags & VEXPORT)
    350 				*ep++ = vp->text;
    351 	}
    352 	*ep = NULL;
    353 	return env;
    354 }
    355 
    356 
    357 /*
    358  * Called when a shell procedure is invoked to clear out nonexported
    359  * variables.  It is also necessary to reallocate variables of with
    360  * VSTACK set since these are currently allocated on the stack.
    361  */
    362 
    363 #ifdef mkinit
    364 MKINIT void shprocvar();
    365 
    366 SHELLPROC {
    367 	shprocvar();
    368 }
    369 #endif
    370 
    371 void
    372 shprocvar() {
    373 	struct var **vpp;
    374 	struct var *vp, **prev;
    375 
    376 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    377 		for (prev = vpp ; (vp = *prev) != NULL ; ) {
    378 			if ((vp->flags & VEXPORT) == 0) {
    379 				*prev = vp->next;
    380 				if ((vp->flags & VTEXTFIXED) == 0)
    381 					ckfree(vp->text);
    382 				if ((vp->flags & VSTRFIXED) == 0)
    383 					ckfree(vp);
    384 			} else {
    385 				if (vp->flags & VSTACK) {
    386 					vp->text = savestr(vp->text);
    387 					vp->flags &=~ VSTACK;
    388 				}
    389 				prev = &vp->next;
    390 			}
    391 		}
    392 	}
    393 	initvar();
    394 }
    395 
    396 
    397 
    398 /*
    399  * Command to list all variables which are set.  Currently this command
    400  * is invoked from the set command when the set command is called without
    401  * any variables.
    402  */
    403 
    404 int
    405 showvarscmd(argc, argv)  char **argv; {
    406 	struct var **vpp;
    407 	struct var *vp;
    408 
    409 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    410 		for (vp = *vpp ; vp ; vp = vp->next) {
    411 			if ((vp->flags & VUNSET) == 0)
    412 				out1fmt("%s\n", vp->text);
    413 		}
    414 	}
    415 	return 0;
    416 }
    417 
    418 
    419 
    420 /*
    421  * The export and readonly commands.
    422  */
    423 
    424 int
    425 exportcmd(argc, argv)  char **argv; {
    426 	struct var **vpp;
    427 	struct var *vp;
    428 	char *name;
    429 	char *p;
    430 	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
    431 
    432 	listsetvar(cmdenviron);
    433 	if (argc > 1) {
    434 		while ((name = *argptr++) != NULL) {
    435 			if ((p = strchr(name, '=')) != NULL) {
    436 				p++;
    437 			} else {
    438 				vpp = hashvar(name);
    439 				for (vp = *vpp ; vp ; vp = vp->next) {
    440 					if (varequal(vp->text, name)) {
    441 						vp->flags |= flag;
    442 						goto found;
    443 					}
    444 				}
    445 			}
    446 			setvar(name, p, flag);
    447 found:;
    448 		}
    449 	} else {
    450 		for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    451 			for (vp = *vpp ; vp ; vp = vp->next) {
    452 				if (vp->flags & flag) {
    453 					for (p = vp->text ; *p != '=' ; p++)
    454 						out1c(*p);
    455 					out1c('\n');
    456 				}
    457 			}
    458 		}
    459 	}
    460 	return 0;
    461 }
    462 
    463 
    464 /*
    465  * The "local" command.
    466  */
    467 
    468 localcmd(argc, argv)  char **argv; {
    469 	char *name;
    470 
    471 	if (! in_function())
    472 		error("Not in a function");
    473 	while ((name = *argptr++) != NULL) {
    474 		mklocal(name);
    475 	}
    476 	return 0;
    477 }
    478 
    479 
    480 /*
    481  * Make a variable a local variable.  When a variable is made local, it's
    482  * value and flags are saved in a localvar structure.  The saved values
    483  * will be restored when the shell function returns.  We handle the name
    484  * "-" as a special case.
    485  */
    486 
    487 void
    488 mklocal(name)
    489 	char *name;
    490 	{
    491 	struct localvar *lvp;
    492 	struct var **vpp;
    493 	struct var *vp;
    494 
    495 	INTOFF;
    496 	lvp = ckmalloc(sizeof (struct localvar));
    497 	if (name[0] == '-' && name[1] == '\0') {
    498 		lvp->text = ckmalloc(sizeof optlist);
    499 		bcopy(optlist, lvp->text, sizeof optlist);
    500 		vp = NULL;
    501 	} else {
    502 		vpp = hashvar(name);
    503 		for (vp = *vpp ; vp && ! varequal(vp->text, name) ; vp = vp->next);
    504 		if (vp == NULL) {
    505 			if (strchr(name, '='))
    506 				setvareq(savestr(name), VSTRFIXED);
    507 			else
    508 				setvar(name, NULL, VSTRFIXED);
    509 			vp = *vpp;	/* the new variable */
    510 			lvp->text = NULL;
    511 			lvp->flags = VUNSET;
    512 		} else {
    513 			lvp->text = vp->text;
    514 			lvp->flags = vp->flags;
    515 			vp->flags |= VSTRFIXED|VTEXTFIXED;
    516 			if (strchr(name, '='))
    517 				setvareq(savestr(name), 0);
    518 		}
    519 	}
    520 	lvp->vp = vp;
    521 	lvp->next = localvars;
    522 	localvars = lvp;
    523 	INTON;
    524 }
    525 
    526 
    527 /*
    528  * Called after a function returns.
    529  */
    530 
    531 void
    532 poplocalvars() {
    533 	struct localvar *lvp;
    534 	struct var *vp;
    535 
    536 	while ((lvp = localvars) != NULL) {
    537 		localvars = lvp->next;
    538 		vp = lvp->vp;
    539 		if (vp == NULL) {	/* $- saved */
    540 			bcopy(lvp->text, optlist, sizeof optlist);
    541 			ckfree(lvp->text);
    542 		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
    543 			(void)unsetvar(vp->text);
    544 		} else {
    545 			if ((vp->flags & VTEXTFIXED) == 0)
    546 				ckfree(vp->text);
    547 			vp->flags = lvp->flags;
    548 			vp->text = lvp->text;
    549 		}
    550 		ckfree(lvp);
    551 	}
    552 }
    553 
    554 
    555 setvarcmd(argc, argv)  char **argv; {
    556 	if (argc <= 2)
    557 		return unsetcmd(argc, argv);
    558 	else if (argc == 3)
    559 		setvar(argv[1], argv[2], 0);
    560 	else
    561 		error("List assignment not implemented");
    562 	return 0;
    563 }
    564 
    565 
    566 /*
    567  * The unset builtin command.  We unset the function before we unset the
    568  * variable to allow a function to be unset when there is a readonly variable
    569  * with the same name.
    570  */
    571 
    572 unsetcmd(argc, argv)  char **argv; {
    573 	char **ap;
    574 	int i;
    575 	int flg_func = 0;
    576 	int flg_var = 0;
    577 	int ret = 0;
    578 
    579 	while ((i = nextopt("vf")) != '\0') {
    580 		if (i == 'f')
    581 			flg_func = 1;
    582 		else
    583 			flg_var = 1;
    584 	}
    585 	if (flg_func == 0 && flg_var == 0)
    586 		flg_var = 1;
    587 
    588 	for (ap = argptr; *ap ; ap++) {
    589 		if (flg_func)
    590 			ret |= unsetfunc(*ap);
    591 		if (flg_var)
    592 			ret |= unsetvar(*ap);
    593 	}
    594 	return ret;
    595 }
    596 
    597 
    598 /*
    599  * Unset the specified variable.
    600  */
    601 
    602 STATIC int
    603 unsetvar(s)
    604 	char *s;
    605 	{
    606 	struct var **vpp;
    607 	struct var *vp;
    608 
    609 	vpp = hashvar(s);
    610 	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
    611 		if (varequal(vp->text, s)) {
    612 			if (vp->flags & VREADONLY)
    613 				return (1);
    614 			INTOFF;
    615 			if (*(strchr(vp->text, '=') + 1) != '\0')
    616 				setvar(s, nullstr, 0);
    617 			vp->flags &=~ VEXPORT;
    618 			vp->flags |= VUNSET;
    619 			if ((vp->flags & VSTRFIXED) == 0) {
    620 				if ((vp->flags & VTEXTFIXED) == 0)
    621 					ckfree(vp->text);
    622 				*vpp = vp->next;
    623 				ckfree(vp);
    624 			}
    625 			INTON;
    626 			return (0);
    627 		}
    628 	}
    629 
    630 	return (1);
    631 }
    632 
    633 
    634 
    635 /*
    636  * Find the appropriate entry in the hash table from the name.
    637  */
    638 
    639 STATIC struct var **
    640 hashvar(p)
    641 	register char *p;
    642 	{
    643 	unsigned int hashval;
    644 
    645 	hashval = *p << 4;
    646 	while (*p && *p != '=')
    647 		hashval += *p++;
    648 	return &vartab[hashval % VTABSIZE];
    649 }
    650 
    651 
    652 
    653 /*
    654  * Returns true if the two strings specify the same varable.  The first
    655  * variable name is terminated by '='; the second may be terminated by
    656  * either '=' or '\0'.
    657  */
    658 
    659 STATIC int
    660 varequal(p, q)
    661 	register char *p, *q;
    662 	{
    663 	while (*p == *q++) {
    664 		if (*p++ == '=')
    665 			return 1;
    666 	}
    667 	if (*p == '=' && *(q - 1) == '\0')
    668 		return 1;
    669 	return 0;
    670 }
    671