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var.c revision 1.1 
      1 /*-
      2  * Copyright (c) 1991 The Regents of the University of California.
      3  * 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	5.3 (Berkeley) 4/12/91";
     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 vifs;
     74 struct var vmail;
     75 struct var vmpath;
     76 struct var vpath;
     77 struct var vps1;
     78 struct var vps2;
     79 struct var vvers;
     80 #if ATTY
     81 struct var vterm;
     82 #endif
     83 
     84 const struct varinit varinit[] = {
     85 #if ATTY
     86 	{&vatty,	VSTRFIXED|VTEXTFIXED|VUNSET,	"ATTY="},
     87 #endif
     88 	{&vifs,	VSTRFIXED|VTEXTFIXED,		"IFS= \t\n"},
     89 	{&vmail,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAIL="},
     90 	{&vmpath,	VSTRFIXED|VTEXTFIXED|VUNSET,	"MAILPATH="},
     91 	{&vpath,	VSTRFIXED|VTEXTFIXED,		"PATH=:/bin:/usr/bin"},
     92 	/*
     93 	 * vps1 depends on uid
     94 	 */
     95 	{&vps2,	VSTRFIXED|VTEXTFIXED,		"PS2=> "},
     96 #if ATTY
     97 	{&vterm,	VSTRFIXED|VTEXTFIXED|VUNSET,	"TERM="},
     98 #endif
     99 	{NULL,	0,				NULL}
    100 };
    101 
    102 struct var *vartab[VTABSIZE];
    103 
    104 STATIC void unsetvar __P((char *));
    105 STATIC struct var **hashvar __P((char *));
    106 STATIC int varequal __P((char *, char *));
    107 
    108 /*
    109  * Initialize the varable symbol tables and import the environment
    110  */
    111 
    112 #ifdef mkinit
    113 INCLUDE "var.h"
    114 INIT {
    115 	char **envp;
    116 	extern char **environ;
    117 
    118 	initvar();
    119 	for (envp = environ ; *envp ; envp++) {
    120 		if (strchr(*envp, '=')) {
    121 			setvareq(*envp, VEXPORT|VTEXTFIXED);
    122 		}
    123 	}
    124 }
    125 #endif
    126 
    127 
    128 /*
    129  * This routine initializes the builtin variables.  It is called when the
    130  * shell is initialized and again when a shell procedure is spawned.
    131  */
    132 
    133 void
    134 initvar() {
    135 	const struct varinit *ip;
    136 	struct var *vp;
    137 	struct var **vpp;
    138 
    139 	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
    140 		if ((vp->flags & VEXPORT) == 0) {
    141 			vpp = hashvar(ip->text);
    142 			vp->next = *vpp;
    143 			*vpp = vp;
    144 			vp->text = ip->text;
    145 			vp->flags = ip->flags;
    146 		}
    147 	}
    148 	/*
    149 	 * PS1 depends on uid
    150 	 */
    151 	if ((vps1.flags & VEXPORT) == 0) {
    152 		vpp = hashvar("PS1=");
    153 		vps1.next = *vpp;
    154 		*vpp = &vps1;
    155 		vps1.text = getuid() ? "PS1=$ " : "PS1=# ";
    156 		vps1.flags = VSTRFIXED|VTEXTFIXED;
    157 	}
    158 }
    159 
    160 /*
    161  * Set the value of a variable.  The flags argument is ored with the
    162  * flags of the variable.  If val is NULL, the variable is unset.
    163  */
    164 
    165 void
    166 setvar(name, val, flags)
    167 	char *name, *val;
    168 	{
    169 	char *p, *q;
    170 	int len;
    171 	int namelen;
    172 	char *nameeq;
    173 	int isbad;
    174 
    175 	isbad = 0;
    176 	p = name;
    177 	if (! is_name(*p++))
    178 		isbad = 1;
    179 	for (;;) {
    180 		if (! is_in_name(*p)) {
    181 			if (*p == '\0' || *p == '=')
    182 				break;
    183 			isbad = 1;
    184 		}
    185 		p++;
    186 	}
    187 	namelen = p - name;
    188 	if (isbad)
    189 		error("%.*s: is read only", namelen, name);
    190 	len = namelen + 2;		/* 2 is space for '=' and '\0' */
    191 	if (val == NULL) {
    192 		flags |= VUNSET;
    193 	} else {
    194 		len += strlen(val);
    195 	}
    196 	p = nameeq = ckmalloc(len);
    197 	q = name;
    198 	while (--namelen >= 0)
    199 		*p++ = *q++;
    200 	*p++ = '=';
    201 	*p = '\0';
    202 	if (val)
    203 		scopy(val, p);
    204 	setvareq(nameeq, flags);
    205 }
    206 
    207 
    208 
    209 /*
    210  * Same as setvar except that the variable and value are passed in
    211  * the first argument as name=value.  Since the first argument will
    212  * be actually stored in the table, it should not be a string that
    213  * will go away.
    214  */
    215 
    216 void
    217 setvareq(s, flags)
    218 	char *s;
    219 	{
    220 	struct var *vp, **vpp;
    221 
    222 	vpp = hashvar(s);
    223 	for (vp = *vpp ; vp ; vp = vp->next) {
    224 		if (varequal(s, vp->text)) {
    225 			if (vp->flags & VREADONLY) {
    226 				int len = strchr(s, '=') - s;
    227 				error("%.*s: is read only", len, s);
    228 			}
    229 			INTOFF;
    230 			if (vp == &vpath)
    231 				changepath(s + 5);	/* 5 = strlen("PATH=") */
    232 			if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
    233 				ckfree(vp->text);
    234 			vp->flags &=~ (VTEXTFIXED|VSTACK|VUNSET);
    235 			vp->flags |= flags;
    236 			vp->text = s;
    237 			if (vp == &vmpath || (vp == &vmail && ! mpathset()))
    238 				chkmail(1);
    239 			INTON;
    240 			return;
    241 		}
    242 	}
    243 	/* not found */
    244 	vp = ckmalloc(sizeof (*vp));
    245 	vp->flags = flags;
    246 	vp->text = s;
    247 	vp->next = *vpp;
    248 	*vpp = vp;
    249 }
    250 
    251 
    252 
    253 /*
    254  * Process a linked list of variable assignments.
    255  */
    256 
    257 void
    258 listsetvar(list)
    259 	struct strlist *list;
    260 	{
    261 	struct strlist *lp;
    262 
    263 	INTOFF;
    264 	for (lp = list ; lp ; lp = lp->next) {
    265 		setvareq(savestr(lp->text), 0);
    266 	}
    267 	INTON;
    268 }
    269 
    270 
    271 
    272 /*
    273  * Find the value of a variable.  Returns NULL if not set.
    274  */
    275 
    276 char *
    277 lookupvar(name)
    278 	char *name;
    279 	{
    280 	struct var *v;
    281 
    282 	for (v = *hashvar(name) ; v ; v = v->next) {
    283 		if (varequal(v->text, name)) {
    284 			if (v->flags & VUNSET)
    285 				return NULL;
    286 			return strchr(v->text, '=') + 1;
    287 		}
    288 	}
    289 	return NULL;
    290 }
    291 
    292 
    293 
    294 /*
    295  * Search the environment of a builtin command.  If the second argument
    296  * is nonzero, return the value of a variable even if it hasn't been
    297  * exported.
    298  */
    299 
    300 char *
    301 bltinlookup(name, doall)
    302 	char *name;
    303 	{
    304 	struct strlist *sp;
    305 	struct var *v;
    306 
    307 	for (sp = cmdenviron ; sp ; sp = sp->next) {
    308 		if (varequal(sp->text, name))
    309 			return strchr(sp->text, '=') + 1;
    310 	}
    311 	for (v = *hashvar(name) ; v ; v = v->next) {
    312 		if (varequal(v->text, name)) {
    313 			if (v->flags & VUNSET
    314 			 || ! doall && (v->flags & VEXPORT) == 0)
    315 				return NULL;
    316 			return strchr(v->text, '=') + 1;
    317 		}
    318 	}
    319 	return NULL;
    320 }
    321 
    322 
    323 
    324 /*
    325  * Generate a list of exported variables.  This routine is used to construct
    326  * the third argument to execve when executing a program.
    327  */
    328 
    329 char **
    330 environment() {
    331 	int nenv;
    332 	struct var **vpp;
    333 	struct var *vp;
    334 	char **env, **ep;
    335 
    336 	nenv = 0;
    337 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    338 		for (vp = *vpp ; vp ; vp = vp->next)
    339 			if (vp->flags & VEXPORT)
    340 				nenv++;
    341 	}
    342 	ep = env = stalloc((nenv + 1) * sizeof *env);
    343 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    344 		for (vp = *vpp ; vp ; vp = vp->next)
    345 			if (vp->flags & VEXPORT)
    346 				*ep++ = vp->text;
    347 	}
    348 	*ep = NULL;
    349 	return env;
    350 }
    351 
    352 
    353 /*
    354  * Called when a shell procedure is invoked to clear out nonexported
    355  * variables.  It is also necessary to reallocate variables of with
    356  * VSTACK set since these are currently allocated on the stack.
    357  */
    358 
    359 #ifdef mkinit
    360 MKINIT void shprocvar();
    361 
    362 SHELLPROC {
    363 	shprocvar();
    364 }
    365 #endif
    366 
    367 void
    368 shprocvar() {
    369 	struct var **vpp;
    370 	struct var *vp, **prev;
    371 
    372 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    373 		for (prev = vpp ; (vp = *prev) != NULL ; ) {
    374 			if ((vp->flags & VEXPORT) == 0) {
    375 				*prev = vp->next;
    376 				if ((vp->flags & VTEXTFIXED) == 0)
    377 					ckfree(vp->text);
    378 				if ((vp->flags & VSTRFIXED) == 0)
    379 					ckfree(vp);
    380 			} else {
    381 				if (vp->flags & VSTACK) {
    382 					vp->text = savestr(vp->text);
    383 					vp->flags &=~ VSTACK;
    384 				}
    385 				prev = &vp->next;
    386 			}
    387 		}
    388 	}
    389 	initvar();
    390 }
    391 
    392 
    393 
    394 /*
    395  * Command to list all variables which are set.  Currently this command
    396  * is invoked from the set command when the set command is called without
    397  * any variables.
    398  */
    399 
    400 int
    401 showvarscmd(argc, argv)  char **argv; {
    402 	struct var **vpp;
    403 	struct var *vp;
    404 
    405 	for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    406 		for (vp = *vpp ; vp ; vp = vp->next) {
    407 			if ((vp->flags & VUNSET) == 0)
    408 				out1fmt("%s\n", vp->text);
    409 		}
    410 	}
    411 	return 0;
    412 }
    413 
    414 
    415 
    416 /*
    417  * The export and readonly commands.
    418  */
    419 
    420 int
    421 exportcmd(argc, argv)  char **argv; {
    422 	struct var **vpp;
    423 	struct var *vp;
    424 	char *name;
    425 	char *p;
    426 	int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
    427 
    428 	listsetvar(cmdenviron);
    429 	if (argc > 1) {
    430 		while ((name = *argptr++) != NULL) {
    431 			if ((p = strchr(name, '=')) != NULL) {
    432 				p++;
    433 			} else {
    434 				vpp = hashvar(name);
    435 				for (vp = *vpp ; vp ; vp = vp->next) {
    436 					if (varequal(vp->text, name)) {
    437 						vp->flags |= flag;
    438 						goto found;
    439 					}
    440 				}
    441 			}
    442 			setvar(name, p, flag);
    443 found:;
    444 		}
    445 	} else {
    446 		for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
    447 			for (vp = *vpp ; vp ; vp = vp->next) {
    448 				if (vp->flags & flag) {
    449 					for (p = vp->text ; *p != '=' ; p++)
    450 						out1c(*p);
    451 					out1c('\n');
    452 				}
    453 			}
    454 		}
    455 	}
    456 	return 0;
    457 }
    458 
    459 
    460 /*
    461  * The "local" command.
    462  */
    463 
    464 localcmd(argc, argv)  char **argv; {
    465 	char *name;
    466 
    467 	if (! in_function())
    468 		error("Not in a function");
    469 	while ((name = *argptr++) != NULL) {
    470 		mklocal(name);
    471 	}
    472 	return 0;
    473 }
    474 
    475 
    476 /*
    477  * Make a variable a local variable.  When a variable is made local, it's
    478  * value and flags are saved in a localvar structure.  The saved values
    479  * will be restored when the shell function returns.  We handle the name
    480  * "-" as a special case.
    481  */
    482 
    483 void
    484 mklocal(name)
    485 	char *name;
    486 	{
    487 	struct localvar *lvp;
    488 	struct var **vpp;
    489 	struct var *vp;
    490 
    491 	INTOFF;
    492 	lvp = ckmalloc(sizeof (struct localvar));
    493 	if (name[0] == '-' && name[1] == '\0') {
    494 		lvp->text = ckmalloc(sizeof optval);
    495 		bcopy(optval, lvp->text, sizeof optval);
    496 		vp = NULL;
    497 	} else {
    498 		vpp = hashvar(name);
    499 		for (vp = *vpp ; vp && ! varequal(vp->text, name) ; vp = vp->next);
    500 		if (vp == NULL) {
    501 			if (strchr(name, '='))
    502 				setvareq(savestr(name), VSTRFIXED);
    503 			else
    504 				setvar(name, NULL, VSTRFIXED);
    505 			vp = *vpp;	/* the new variable */
    506 			lvp->text = NULL;
    507 			lvp->flags = VUNSET;
    508 		} else {
    509 			lvp->text = vp->text;
    510 			lvp->flags = vp->flags;
    511 			vp->flags |= VSTRFIXED|VTEXTFIXED;
    512 			if (strchr(name, '='))
    513 				setvareq(savestr(name), 0);
    514 		}
    515 	}
    516 	lvp->vp = vp;
    517 	lvp->next = localvars;
    518 	localvars = lvp;
    519 	INTON;
    520 }
    521 
    522 
    523 /*
    524  * Called after a function returns.
    525  */
    526 
    527 void
    528 poplocalvars() {
    529 	struct localvar *lvp;
    530 	struct var *vp;
    531 
    532 	while ((lvp = localvars) != NULL) {
    533 		localvars = lvp->next;
    534 		vp = lvp->vp;
    535 		if (vp == NULL) {	/* $- saved */
    536 			bcopy(lvp->text, optval, sizeof optval);
    537 			ckfree(lvp->text);
    538 		} else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
    539 			unsetvar(vp->text);
    540 		} else {
    541 			if ((vp->flags & VTEXTFIXED) == 0)
    542 				ckfree(vp->text);
    543 			vp->flags = lvp->flags;
    544 			vp->text = lvp->text;
    545 		}
    546 		ckfree(lvp);
    547 	}
    548 }
    549 
    550 
    551 setvarcmd(argc, argv)  char **argv; {
    552 	if (argc <= 2)
    553 		return unsetcmd(argc, argv);
    554 	else if (argc == 3)
    555 		setvar(argv[1], argv[2], 0);
    556 	else
    557 		error("List assignment not implemented");
    558 	return 0;
    559 }
    560 
    561 
    562 /*
    563  * The unset builtin command.  We unset the function before we unset the
    564  * variable to allow a function to be unset when there is a readonly variable
    565  * with the same name.
    566  */
    567 
    568 unsetcmd(argc, argv)  char **argv; {
    569 	char **ap;
    570 
    571 	for (ap = argv + 1 ; *ap ; ap++) {
    572 		unsetfunc(*ap);
    573 		unsetvar(*ap);
    574 	}
    575 	return 0;
    576 }
    577 
    578 
    579 /*
    580  * Unset the specified variable.
    581  */
    582 
    583 STATIC void
    584 unsetvar(s)
    585 	char *s;
    586 	{
    587 	struct var **vpp;
    588 	struct var *vp;
    589 
    590 	vpp = hashvar(s);
    591 	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
    592 		if (varequal(vp->text, s)) {
    593 			INTOFF;
    594 			if (*(strchr(vp->text, '=') + 1) != '\0'
    595 			 || vp->flags & VREADONLY) {
    596 				setvar(s, nullstr, 0);
    597 			}
    598 			vp->flags &=~ VEXPORT;
    599 			vp->flags |= VUNSET;
    600 			if ((vp->flags & VSTRFIXED) == 0) {
    601 				if ((vp->flags & VTEXTFIXED) == 0)
    602 					ckfree(vp->text);
    603 				*vpp = vp->next;
    604 				ckfree(vp);
    605 			}
    606 			INTON;
    607 			return;
    608 		}
    609 	}
    610 }
    611 
    612 
    613 
    614 /*
    615  * Find the appropriate entry in the hash table from the name.
    616  */
    617 
    618 STATIC struct var **
    619 hashvar(p)
    620 	register char *p;
    621 	{
    622 	unsigned int hashval;
    623 
    624 	hashval = *p << 4;
    625 	while (*p && *p != '=')
    626 		hashval += *p++;
    627 	return &vartab[hashval % VTABSIZE];
    628 }
    629 
    630 
    631 
    632 /*
    633  * Returns true if the two strings specify the same varable.  The first
    634  * variable name is terminated by '='; the second may be terminated by
    635  * either '=' or '\0'.
    636  */
    637 
    638 STATIC int
    639 varequal(p, q)
    640 	register char *p, *q;
    641 	{
    642 	while (*p == *q++) {
    643 		if (*p++ == '=')
    644 			return 1;
    645 	}
    646 	if (*p == '=' && *(q - 1) == '\0')
    647 		return 1;
    648 	return 0;
    649 }
    650