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 * @(#)var.c 8.3 (Berkeley) 5/4/95 37 * $FreeBSD: src/bin/sh/var.c,v 1.15.2.2 2002/08/27 01:36:28 tjr Exp $ 38 * $DragonFly: src/bin/sh/var.c,v 1.15 2007/01/14 17:29:58 pavalos Exp $ 39 */ 40 41 #include <unistd.h> 42 #include <stdlib.h> 43 44 /* 45 * Shell variables. 46 */ 47 48 #include <locale.h> 49 #include <paths.h> 50 51 #include "shell.h" 52 #include "output.h" 53 #include "expand.h" 54 #include "nodes.h" /* for other headers */ 55 #include "eval.h" /* defines cmdenviron */ 56 #include "exec.h" 57 #include "syntax.h" 58 #include "options.h" 59 #include "mail.h" 60 #include "var.h" 61 #include "memalloc.h" 62 #include "error.h" 63 #include "mystring.h" 64 #include "parser.h" 65 #ifndef NO_HISTORY 66 #include "myhistedit.h" 67 #endif 68 69 70 #define VTABSIZE 39 71 72 73 struct varinit { 74 struct var *var; 75 int flags; 76 const char *text; 77 void (*func)(const char *); 78 }; 79 80 81 #ifndef NO_HISTORY 82 struct var vhistsize; 83 #endif 84 struct var vifs; 85 struct var vmail; 86 struct var vmpath; 87 struct var vpath; 88 struct var vppid; 89 struct var vps1; 90 struct var vps2; 91 struct var vps4; 92 struct var vvers; 93 STATIC struct var voptind; 94 95 STATIC const struct varinit varinit[] = { 96 #ifndef NO_HISTORY 97 { &vhistsize, VSTRFIXED|VTEXTFIXED|VUNSET, "HISTSIZE=", 98 sethistsize }, 99 #endif 100 { &vifs, VSTRFIXED|VTEXTFIXED, "IFS= \t\n", 101 NULL }, 102 { &vmail, VSTRFIXED|VTEXTFIXED|VUNSET, "MAIL=", 103 NULL }, 104 { &vmpath, VSTRFIXED|VTEXTFIXED|VUNSET, "MAILPATH=", 105 NULL }, 106 { &vpath, VSTRFIXED|VTEXTFIXED|VEXPORT, 107 #ifdef _PATH_DEFPATH 108 "PATH=" _PATH_DEFPATH, 109 #else 110 "PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/pkg/bin:/usr/pkg/sbin", 111 #endif 112 changepath }, 113 { &vppid, VSTRFIXED|VTEXTFIXED|VUNSET, "PPID=", 114 NULL }, 115 /* 116 * vps1 depends on uid 117 */ 118 { &vps2, VSTRFIXED|VTEXTFIXED, "PS2=> ", 119 NULL }, 120 { &vps4, VSTRFIXED|VTEXTFIXED, "PS4=+ ", 121 NULL }, 122 { &voptind, VSTRFIXED|VTEXTFIXED, "OPTIND=1", 123 getoptsreset }, 124 { NULL, 0, NULL, 125 NULL } 126 }; 127 128 STATIC struct var *vartab[VTABSIZE]; 129 130 STATIC struct var **hashvar(const char *); 131 STATIC int varequal(const char *, const char *); 132 STATIC int localevar(const char *); 133 134 /* 135 * Initialize the variable symbol tables and import the environment. 136 */ 137 138 #ifdef mkinit 139 INCLUDE "var.h" 140 MKINIT char **environ; 141 INIT { 142 char **envp; 143 144 initvar(); 145 for (envp = environ ; *envp ; envp++) { 146 if (strchr(*envp, '=')) { 147 setvareq(*envp, VEXPORT|VTEXTFIXED); 148 } 149 } 150 } 151 #endif 152 153 154 /* 155 * This routine initializes the builtin variables. It is called when the 156 * shell is initialized and again when a shell procedure is spawned. 157 */ 158 159 void 160 initvar(void) 161 { 162 char ppid[20]; 163 const struct varinit *ip; 164 struct var *vp; 165 struct var **vpp; 166 167 for (ip = varinit ; (vp = ip->var) != NULL ; ip++) { 168 if ((vp->flags & VEXPORT) == 0) { 169 vpp = hashvar(ip->text); 170 vp->next = *vpp; 171 *vpp = vp; 172 vp->text = strdup(ip->text); 173 vp->flags = ip->flags; 174 vp->func = ip->func; 175 } 176 } 177 /* 178 * PS1 depends on uid 179 */ 180 if ((vps1.flags & VEXPORT) == 0) { 181 vpp = hashvar("PS1="); 182 vps1.next = *vpp; 183 *vpp = &vps1; 184 vps1.text = strdup(geteuid() ? "PS1=$ " : "PS1=# "); 185 vps1.flags = VSTRFIXED|VTEXTFIXED; 186 } 187 if ((vppid.flags & VEXPORT) == 0) { 188 fmtstr(ppid, sizeof(ppid), "%d", (int)getppid()); 189 setvarsafe("PPID", ppid, 0); 190 } 191 } 192 193 /* 194 * Safe version of setvar, returns 1 on success 0 on failure. 195 */ 196 197 int 198 setvarsafe(const char *name, const char *val, int flags) 199 { 200 struct jmploc jmploc; 201 struct jmploc *volatile savehandler = handler; 202 int err = 0; 203 204 if (setjmp(jmploc.loc)) 205 err = 1; 206 else { 207 handler = &jmploc; 208 setvar(name, val, flags); 209 } 210 handler = savehandler; 211 return err; 212 } 213 214 /* 215 * Set the value of a variable. The flags argument is stored with the 216 * flags of the variable. If val is NULL, the variable is unset. 217 */ 218 219 void 220 setvar(const char *name, const char *val, int flags) 221 { 222 const char *cp; 223 char *p; 224 int len; 225 int namelen; 226 char *nameeq; 227 int isbad; 228 229 isbad = 0; 230 cp = name; 231 if (!is_name(*cp)) 232 isbad = 1; 233 cp++; 234 for (;;) { 235 if (!is_in_name(*cp)) { 236 if (*cp == '\0' || *cp == '=') 237 break; 238 isbad = 1; 239 } 240 cp++; 241 } 242 namelen = cp - name; 243 if (isbad) 244 error("%.*s: bad variable name", namelen, name); 245 len = namelen + 2; /* 2 is space for '=' and '\0' */ 246 if (val == NULL) { 247 flags |= VUNSET; 248 } else { 249 len += strlen(val); 250 } 251 p = nameeq = ckmalloc(len); 252 cp = name; 253 while (--namelen >= 0) 254 *p++ = *cp++; 255 *p++ = '='; 256 *p = '\0'; 257 if (val) 258 scopy(val, p); 259 setvareq(nameeq, flags); 260 } 261 262 STATIC int 263 localevar(const char *s) 264 { 265 static const char * const lnames[7] = { 266 "ALL", "COLLATE", "CTYPE", "MONETARY", 267 "NUMERIC", "TIME", NULL 268 }; 269 const char * const *ss; 270 271 if (*s != 'L') 272 return 0; 273 if (varequal(s + 1, "ANG")) 274 return 1; 275 if (strncmp(s + 1, "C_", 2) != 0) 276 return 0; 277 for (ss = lnames; *ss ; ss++) 278 if (varequal(s + 3, *ss)) 279 return 1; 280 return 0; 281 } 282 283 /* 284 * Sets/unsets an environment variable from a pointer that may actually be a 285 * pointer into environ where the string should not be manipulated. 286 */ 287 static void 288 change_env(char *s, int set) 289 { 290 char *eqp; 291 char *ss; 292 293 ss = savestr(s); 294 if ((eqp = strchr(ss, '=')) != NULL) 295 *eqp = '\0'; 296 if (set && eqp != NULL) { 297 if (setenv(ss, eqp + 1, 1) != 0) 298 error("setenv: cannot set %s=%s", ss, eqp + 1); 299 } else 300 unsetenv(ss); 301 ckfree(ss); 302 } 303 304 305 /* 306 * Same as setvar except that the variable and value are passed in 307 * the first argument as name=value. Since the first argument will 308 * be actually stored in the table, it should not be a string that 309 * will go away. 310 */ 311 312 void 313 setvareq(char *s, int flags) 314 { 315 struct var *vp, **vpp; 316 int len; 317 318 if (aflag) 319 flags |= VEXPORT; 320 vpp = hashvar(s); 321 for (vp = *vpp ; vp ; vp = vp->next) { 322 if (varequal(s, vp->text)) { 323 if (vp->flags & VREADONLY) { 324 len = strchr(s, '=') - s; 325 error("%.*s: is read only", len, s); 326 } 327 INTOFF; 328 329 if (vp->func && (flags & VNOFUNC) == 0) 330 (*vp->func)(strchr(s, '=') + 1); 331 332 if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0) 333 ckfree(vp->text); 334 335 vp->flags &= ~(VTEXTFIXED|VSTACK|VUNSET); 336 vp->flags |= flags; 337 vp->text = s; 338 339 /* 340 * We could roll this to a function, to handle it as 341 * a regular variable function callback, but why bother? 342 */ 343 if (vp == &vmpath || (vp == &vmail && ! mpathset())) 344 chkmail(1); 345 if ((vp->flags & VEXPORT) && localevar(s)) { 346 change_env(s, 1); 347 setlocale(LC_ALL, ""); 348 } 349 INTON; 350 return; 351 } 352 } 353 /* not found */ 354 vp = ckmalloc(sizeof (*vp)); 355 vp->flags = flags; 356 vp->text = s; 357 vp->next = *vpp; 358 vp->func = NULL; 359 INTOFF; 360 *vpp = vp; 361 if ((vp->flags & VEXPORT) && localevar(s)) { 362 change_env(s, 1); 363 setlocale(LC_ALL, ""); 364 } 365 INTON; 366 } 367 368 369 370 /* 371 * Process a linked list of variable assignments. 372 */ 373 374 void 375 listsetvar(struct strlist *list) 376 { 377 struct strlist *lp; 378 379 INTOFF; 380 for (lp = list ; lp ; lp = lp->next) { 381 setvareq(savestr(lp->text), 0); 382 } 383 INTON; 384 } 385 386 387 388 /* 389 * Find the value of a variable. Returns NULL if not set. 390 */ 391 392 char * 393 lookupvar(const char *name) 394 { 395 struct var *v; 396 397 for (v = *hashvar(name) ; v ; v = v->next) { 398 if (varequal(v->text, name)) { 399 if (v->flags & VUNSET) 400 return NULL; 401 return strchr(v->text, '=') + 1; 402 } 403 } 404 return NULL; 405 } 406 407 408 409 /* 410 * Search the environment of a builtin command. If the second argument 411 * is nonzero, return the value of a variable even if it hasn't been 412 * exported. 413 */ 414 415 char * 416 bltinlookup(const char *name, int doall) 417 { 418 struct strlist *sp; 419 struct var *v; 420 421 for (sp = cmdenviron ; sp ; sp = sp->next) { 422 if (varequal(sp->text, name)) 423 return strchr(sp->text, '=') + 1; 424 } 425 for (v = *hashvar(name) ; v ; v = v->next) { 426 if (varequal(v->text, name)) { 427 if ((v->flags & VUNSET) 428 || (!doall && (v->flags & VEXPORT) == 0)) 429 return NULL; 430 return strchr(v->text, '=') + 1; 431 } 432 } 433 return NULL; 434 } 435 436 437 438 /* 439 * Generate a list of exported variables. This routine is used to construct 440 * the third argument to execve when executing a program. 441 */ 442 443 char ** 444 environment(void) 445 { 446 int nenv; 447 struct var **vpp; 448 struct var *vp; 449 char **env, **ep; 450 451 nenv = 0; 452 for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) { 453 for (vp = *vpp ; vp ; vp = vp->next) 454 if (vp->flags & VEXPORT) 455 nenv++; 456 } 457 ep = env = stalloc((nenv + 1) * sizeof *env); 458 for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) { 459 for (vp = *vpp ; vp ; vp = vp->next) 460 if (vp->flags & VEXPORT) 461 *ep++ = vp->text; 462 } 463 *ep = NULL; 464 return env; 465 } 466 467 468 /* 469 * Called when a shell procedure is invoked to clear out nonexported 470 * variables. It is also necessary to reallocate variables of with 471 * VSTACK set since these are currently allocated on the stack. 472 */ 473 474 #ifdef mkinit 475 void shprocvar(void); 476 477 SHELLPROC { 478 shprocvar(); 479 } 480 #endif 481 482 void 483 shprocvar(void) 484 { 485 struct var **vpp; 486 struct var *vp, **prev; 487 488 for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) { 489 for (prev = vpp ; (vp = *prev) != NULL ; ) { 490 if ((vp->flags & VEXPORT) == 0) { 491 *prev = vp->next; 492 if ((vp->flags & VTEXTFIXED) == 0) 493 ckfree(vp->text); 494 if ((vp->flags & VSTRFIXED) == 0) 495 ckfree(vp); 496 } else { 497 if (vp->flags & VSTACK) { 498 vp->text = savestr(vp->text); 499 vp->flags &=~ VSTACK; 500 } 501 prev = &vp->next; 502 } 503 } 504 } 505 initvar(); 506 } 507 508 509 static int 510 var_compare(const void *a, const void *b) 511 { 512 const char *const *sa, *const *sb; 513 514 sa = a; 515 sb = b; 516 /* 517 * This compares two var=value strings which creates a different 518 * order from what you would probably expect. POSIX is somewhat 519 * ambiguous on what should be sorted exactly. 520 */ 521 return strcoll(*sa, *sb); 522 } 523 524 525 /* 526 * Command to list all variables which are set. Currently this command 527 * is invoked from the set command when the set command is called without 528 * any variables. 529 */ 530 531 int 532 showvarscmd(int argc __unused, char **argv __unused) 533 { 534 struct var **vpp; 535 struct var *vp; 536 const char *s; 537 const char **vars; 538 int i, n; 539 540 /* 541 * POSIX requires us to sort the variables. 542 */ 543 n = 0; 544 for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) { 545 for (vp = *vpp; vp; vp = vp->next) { 546 if (!(vp->flags & VUNSET)) 547 n++; 548 } 549 } 550 551 INTON; 552 vars = ckmalloc(n * sizeof(*vars)); 553 i = 0; 554 for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) { 555 for (vp = *vpp; vp; vp = vp->next) { 556 if (!(vp->flags & VUNSET)) 557 vars[i++] = vp->text; 558 } 559 } 560 561 qsort(vars, n, sizeof(*vars), var_compare); 562 for (i = 0; i < n; i++) { 563 for (s = vars[i]; *s != '='; s++) 564 out1c(*s); 565 out1c('='); 566 out1qstr(s + 1); 567 out1c('\n'); 568 } 569 ckfree(vars); 570 INTOFF; 571 572 return 0; 573 } 574 575 576 577 /* 578 * The export and readonly commands. 579 */ 580 581 int 582 exportcmd(int argc, char **argv) 583 { 584 struct var **vpp; 585 struct var *vp; 586 char *name; 587 char *p; 588 char *cmdname; 589 int ch, values; 590 int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT; 591 592 cmdname = argv[0]; 593 optreset = optind = 1; 594 opterr = 0; 595 values = 0; 596 while ((ch = getopt(argc, argv, "p")) != -1) { 597 switch (ch) { 598 case 'p': 599 values = 1; 600 break; 601 case '?': 602 default: 603 error("unknown option: -%c", optopt); 604 } 605 } 606 argc -= optind; 607 argv += optind; 608 609 if (values && argc != 0) 610 error("-p requires no arguments"); 611 listsetvar(cmdenviron); 612 if (argc != 0) { 613 while ((name = *argv++) != NULL) { 614 if ((p = strchr(name, '=')) != NULL) { 615 p++; 616 } else { 617 vpp = hashvar(name); 618 for (vp = *vpp ; vp ; vp = vp->next) { 619 if (varequal(vp->text, name)) { 620 621 vp->flags |= flag; 622 if ((vp->flags & VEXPORT) && localevar(vp->text)) { 623 change_env(vp->text, 1); 624 setlocale(LC_ALL, ""); 625 } 626 goto found; 627 } 628 } 629 } 630 setvar(name, p, flag); 631 found:; 632 } 633 } else { 634 for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) { 635 for (vp = *vpp ; vp ; vp = vp->next) { 636 if (vp->flags & flag) { 637 if (values) { 638 out1str(cmdname); 639 out1c(' '); 640 } 641 for (p = vp->text ; *p != '=' ; p++) 642 out1c(*p); 643 if (values && !(vp->flags & VUNSET)) { 644 out1c('='); 645 out1qstr(p + 1); 646 } 647 out1c('\n'); 648 } 649 } 650 } 651 } 652 return 0; 653 } 654 655 656 /* 657 * The "local" command. 658 */ 659 660 int 661 localcmd(int argc __unused, char **argv __unused) 662 { 663 char *name; 664 665 if (! in_function()) 666 error("Not in a function"); 667 while ((name = *argptr++) != NULL) { 668 mklocal(name); 669 } 670 return 0; 671 } 672 673 674 /* 675 * Make a variable a local variable. When a variable is made local, it's 676 * value and flags are saved in a localvar structure. The saved values 677 * will be restored when the shell function returns. We handle the name 678 * "-" as a special case. 679 */ 680 681 void 682 mklocal(char *name) 683 { 684 struct localvar *lvp; 685 struct var **vpp; 686 struct var *vp; 687 688 INTOFF; 689 lvp = ckmalloc(sizeof (struct localvar)); 690 if (name[0] == '-' && name[1] == '\0') { 691 lvp->text = ckmalloc(sizeof optlist); 692 memcpy(lvp->text, optlist, sizeof optlist); 693 vp = NULL; 694 } else { 695 vpp = hashvar(name); 696 for (vp = *vpp ; vp && ! varequal(vp->text, name) ; vp = vp->next); 697 if (vp == NULL) { 698 if (strchr(name, '=')) 699 setvareq(savestr(name), VSTRFIXED); 700 else 701 setvar(name, NULL, VSTRFIXED); 702 vp = *vpp; /* the new variable */ 703 lvp->text = NULL; 704 lvp->flags = VUNSET; 705 } else { 706 lvp->text = vp->text; 707 lvp->flags = vp->flags; 708 vp->flags |= VSTRFIXED|VTEXTFIXED; 709 if (strchr(name, '=')) 710 setvareq(savestr(name), 0); 711 } 712 } 713 lvp->vp = vp; 714 lvp->next = localvars; 715 localvars = lvp; 716 INTON; 717 } 718 719 720 /* 721 * Called after a function returns. 722 */ 723 724 void 725 poplocalvars(void) 726 { 727 struct localvar *lvp; 728 struct var *vp; 729 730 while ((lvp = localvars) != NULL) { 731 localvars = lvp->next; 732 vp = lvp->vp; 733 if (vp == NULL) { /* $- saved */ 734 memcpy(optlist, lvp->text, sizeof optlist); 735 ckfree(lvp->text); 736 } else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) { 737 unsetvar(vp->text); 738 } else { 739 if ((vp->flags & VTEXTFIXED) == 0) 740 ckfree(vp->text); 741 vp->flags = lvp->flags; 742 vp->text = lvp->text; 743 } 744 ckfree(lvp); 745 } 746 } 747 748 749 int 750 setvarcmd(int argc, char **argv) 751 { 752 if (argc <= 2) 753 return unsetcmd(argc, argv); 754 else if (argc == 3) 755 setvar(argv[1], argv[2], 0); 756 else 757 error("List assignment not implemented"); 758 return 0; 759 } 760 761 762 /* 763 * The unset builtin command. We unset the function before we unset the 764 * variable to allow a function to be unset when there is a readonly variable 765 * with the same name. 766 */ 767 768 int 769 unsetcmd(int argc __unused, char **argv __unused) 770 { 771 char **ap; 772 int i; 773 int flg_func = 0; 774 int flg_var = 0; 775 int ret = 0; 776 777 while ((i = nextopt("vf")) != '\0') { 778 if (i == 'f') 779 flg_func = 1; 780 else 781 flg_var = 1; 782 } 783 if (flg_func == 0 && flg_var == 0) 784 flg_var = 1; 785 786 for (ap = argptr; *ap ; ap++) { 787 if (flg_func) 788 ret |= unsetfunc(*ap); 789 if (flg_var) 790 ret |= unsetvar(*ap); 791 } 792 return ret; 793 } 794 795 796 /* 797 * Unset the specified variable. 798 */ 799 800 int 801 unsetvar(const char *s) 802 { 803 struct var **vpp; 804 struct var *vp; 805 806 vpp = hashvar(s); 807 for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) { 808 if (varequal(vp->text, s)) { 809 if (vp->flags & VREADONLY) 810 return (1); 811 INTOFF; 812 if (*(strchr(vp->text, '=') + 1) != '\0') 813 setvar(s, nullstr, 0); 814 if ((vp->flags & VEXPORT) && localevar(vp->text)) { 815 change_env(__DECONST(char *, s), 0); 816 setlocale(LC_ALL, ""); 817 } 818 vp->flags &= ~VEXPORT; 819 vp->flags |= VUNSET; 820 if ((vp->flags & VSTRFIXED) == 0) { 821 if ((vp->flags & VTEXTFIXED) == 0) 822 ckfree(vp->text); 823 *vpp = vp->next; 824 ckfree(vp); 825 } 826 INTON; 827 return (0); 828 } 829 } 830 return (0); 831 } 832 833 834 835 /* 836 * Find the appropriate entry in the hash table from the name. 837 */ 838 839 STATIC struct var ** 840 hashvar(const char *p) 841 { 842 unsigned int hashval; 843 844 hashval = ((unsigned char) *p) << 4; 845 while (*p && *p != '=') 846 hashval += (unsigned char) *p++; 847 return &vartab[hashval % VTABSIZE]; 848 } 849 850 851 852 /* 853 * Returns true if the two strings specify the same varable. The first 854 * variable name is terminated by '='; the second may be terminated by 855 * either '=' or '\0'. 856 */ 857 858 STATIC int 859 varequal(const char *p, const char *q) 860 { 861 while (*p == *q++) { 862 if (*p++ == '=') 863 return 1; 864 } 865 if (*p == '=' && *(q - 1) == '\0') 866 return 1; 867 return 0; 868 } 869