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 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #ifndef lint 34 #if 0 35 static char sccsid[] = "@(#)exec.c 8.4 (Berkeley) 6/8/95"; 36 #endif 37 #endif /* not lint */ 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include <sys/types.h> 42 #include <sys/stat.h> 43 #include <unistd.h> 44 #include <fcntl.h> 45 #include <errno.h> 46 #include <paths.h> 47 #include <stdlib.h> 48 49 /* 50 * When commands are first encountered, they are entered in a hash table. 51 * This ensures that a full path search will not have to be done for them 52 * on each invocation. 53 * 54 * We should investigate converting to a linear search, even though that 55 * would make the command name "hash" a misnomer. 56 */ 57 58 #include "shell.h" 59 #include "main.h" 60 #include "nodes.h" 61 #include "parser.h" 62 #include "redir.h" 63 #include "eval.h" 64 #include "exec.h" 65 #include "builtins.h" 66 #include "var.h" 67 #include "options.h" 68 #include "input.h" 69 #include "output.h" 70 #include "syntax.h" 71 #include "memalloc.h" 72 #include "error.h" 73 #include "mystring.h" 74 #include "show.h" 75 #include "jobs.h" 76 #include "alias.h" 77 78 79 #define CMDTABLESIZE 31 /* should be prime */ 80 81 82 83 struct tblentry { 84 struct tblentry *next; /* next entry in hash chain */ 85 union param param; /* definition of builtin function */ 86 int special; /* flag for special builtin commands */ 87 signed char cmdtype; /* index identifying command */ 88 char cmdname[]; /* name of command */ 89 }; 90 91 92 static struct tblentry *cmdtable[CMDTABLESIZE]; 93 static int cmdtable_cd = 0; /* cmdtable contains cd-dependent entries */ 94 int exerrno = 0; /* Last exec error */ 95 96 97 static void tryexec(char *, char **, char **); 98 static void printentry(struct tblentry *, int); 99 static struct tblentry *cmdlookup(const char *, int); 100 static void delete_cmd_entry(void); 101 static void addcmdentry(const char *, struct cmdentry *); 102 103 104 105 /* 106 * Exec a program. Never returns. If you change this routine, you may 107 * have to change the find_command routine as well. 108 * 109 * The argv array may be changed and element argv[-1] should be writable. 110 */ 111 112 void 113 shellexec(char **argv, char **envp, const char *path, int idx) 114 { 115 char *cmdname; 116 int e; 117 118 if (strchr(argv[0], '/') != NULL) { 119 tryexec(argv[0], argv, envp); 120 e = errno; 121 } else { 122 e = ENOENT; 123 while ((cmdname = padvance(&path, argv[0])) != NULL) { 124 if (--idx < 0 && pathopt == NULL) { 125 tryexec(cmdname, argv, envp); 126 if (errno != ENOENT && errno != ENOTDIR) 127 e = errno; 128 if (e == ENOEXEC) 129 break; 130 } 131 stunalloc(cmdname); 132 } 133 } 134 135 /* Map to POSIX errors */ 136 if (e == ENOENT || e == ENOTDIR) { 137 exerrno = 127; 138 exerror(EXEXEC, "%s: not found", argv[0]); 139 } else { 140 exerrno = 126; 141 exerror(EXEXEC, "%s: %s", argv[0], strerror(e)); 142 } 143 } 144 145 146 static void 147 tryexec(char *cmd, char **argv, char **envp) 148 { 149 int e, in; 150 ssize_t n; 151 char buf[256]; 152 153 execve(cmd, argv, envp); 154 e = errno; 155 if (e == ENOEXEC) { 156 INTOFF; 157 in = open(cmd, O_RDONLY | O_NONBLOCK); 158 if (in != -1) { 159 n = pread(in, buf, sizeof buf, 0); 160 close(in); 161 if (n > 0 && memchr(buf, '\0', n) != NULL) { 162 errno = ENOEXEC; 163 return; 164 } 165 } 166 *argv = cmd; 167 *--argv = __DECONST(char *, _PATH_BSHELL); 168 execve(_PATH_BSHELL, argv, envp); 169 } 170 errno = e; 171 } 172 173 /* 174 * Do a path search. The variable path (passed by reference) should be 175 * set to the start of the path before the first call; padvance will update 176 * this value as it proceeds. Successive calls to padvance will return 177 * the possible path expansions in sequence. If an option (indicated by 178 * a percent sign) appears in the path entry then the global variable 179 * pathopt will be set to point to it; otherwise pathopt will be set to 180 * NULL. 181 */ 182 183 const char *pathopt; 184 185 char * 186 padvance(const char **path, const char *name) 187 { 188 const char *p, *start; 189 char *q; 190 size_t len; 191 192 if (*path == NULL) 193 return NULL; 194 start = *path; 195 for (p = start; *p && *p != ':' && *p != '%'; p++) 196 ; /* nothing */ 197 len = p - start + strlen(name) + 2; /* "2" is for '/' and '\0' */ 198 STARTSTACKSTR(q); 199 CHECKSTRSPACE(len, q); 200 if (p != start) { 201 memcpy(q, start, p - start); 202 q += p - start; 203 *q++ = '/'; 204 } 205 strcpy(q, name); 206 pathopt = NULL; 207 if (*p == '%') { 208 pathopt = ++p; 209 while (*p && *p != ':') p++; 210 } 211 if (*p == ':') 212 *path = p + 1; 213 else 214 *path = NULL; 215 return stalloc(len); 216 } 217 218 219 220 /*** Command hashing code ***/ 221 222 223 int 224 hashcmd(int argc __unused, char **argv __unused) 225 { 226 struct tblentry **pp; 227 struct tblentry *cmdp; 228 int c; 229 int verbose; 230 struct cmdentry entry; 231 char *name; 232 int errors; 233 234 errors = 0; 235 verbose = 0; 236 while ((c = nextopt("rv")) != '\0') { 237 if (c == 'r') { 238 clearcmdentry(); 239 } else if (c == 'v') { 240 verbose++; 241 } 242 } 243 if (*argptr == NULL) { 244 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { 245 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 246 if (cmdp->cmdtype == CMDNORMAL) 247 printentry(cmdp, verbose); 248 } 249 } 250 return 0; 251 } 252 while ((name = *argptr) != NULL) { 253 if ((cmdp = cmdlookup(name, 0)) != NULL 254 && cmdp->cmdtype == CMDNORMAL) 255 delete_cmd_entry(); 256 find_command(name, &entry, DO_ERR, pathval()); 257 if (entry.cmdtype == CMDUNKNOWN) 258 errors = 1; 259 else if (verbose) { 260 cmdp = cmdlookup(name, 0); 261 if (cmdp != NULL) 262 printentry(cmdp, verbose); 263 else { 264 outfmt(out2, "%s: not found\n", name); 265 errors = 1; 266 } 267 flushall(); 268 } 269 argptr++; 270 } 271 return errors; 272 } 273 274 275 static void 276 printentry(struct tblentry *cmdp, int verbose) 277 { 278 int idx; 279 const char *path; 280 char *name; 281 282 if (cmdp->cmdtype == CMDNORMAL) { 283 idx = cmdp->param.index; 284 path = pathval(); 285 do { 286 name = padvance(&path, cmdp->cmdname); 287 stunalloc(name); 288 } while (--idx >= 0); 289 out1str(name); 290 } else if (cmdp->cmdtype == CMDBUILTIN) { 291 out1fmt("builtin %s", cmdp->cmdname); 292 } else if (cmdp->cmdtype == CMDFUNCTION) { 293 out1fmt("function %s", cmdp->cmdname); 294 if (verbose) { 295 INTOFF; 296 name = commandtext(getfuncnode(cmdp->param.func)); 297 out1c(' '); 298 out1str(name); 299 ckfree(name); 300 INTON; 301 } 302 #ifdef DEBUG 303 } else { 304 error("internal error: cmdtype %d", cmdp->cmdtype); 305 #endif 306 } 307 out1c('\n'); 308 } 309 310 311 312 /* 313 * Resolve a command name. If you change this routine, you may have to 314 * change the shellexec routine as well. 315 */ 316 317 void 318 find_command(const char *name, struct cmdentry *entry, int act, 319 const char *path) 320 { 321 struct tblentry *cmdp, loc_cmd; 322 int idx; 323 char *fullname; 324 struct stat statb; 325 int e; 326 int i; 327 int spec; 328 int cd; 329 330 /* If name contains a slash, don't use the hash table */ 331 if (strchr(name, '/') != NULL) { 332 entry->cmdtype = CMDNORMAL; 333 entry->u.index = 0; 334 return; 335 } 336 337 cd = 0; 338 339 /* If name is in the table, and not invalidated by cd, we're done */ 340 if ((cmdp = cmdlookup(name, 0)) != NULL) { 341 if (cmdp->cmdtype == CMDFUNCTION && act & DO_NOFUNC) 342 cmdp = NULL; 343 else 344 goto success; 345 } 346 347 /* Check for builtin next */ 348 if ((i = find_builtin(name, &spec)) >= 0) { 349 INTOFF; 350 cmdp = cmdlookup(name, 1); 351 if (cmdp->cmdtype == CMDFUNCTION) 352 cmdp = &loc_cmd; 353 cmdp->cmdtype = CMDBUILTIN; 354 cmdp->param.index = i; 355 cmdp->special = spec; 356 INTON; 357 goto success; 358 } 359 360 /* We have to search path. */ 361 362 e = ENOENT; 363 idx = -1; 364 loop: 365 while ((fullname = padvance(&path, name)) != NULL) { 366 stunalloc(fullname); 367 idx++; 368 if (pathopt) { 369 if (prefix("func", pathopt)) { 370 /* handled below */ 371 } else { 372 goto loop; /* ignore unimplemented options */ 373 } 374 } 375 if (fullname[0] != '/') 376 cd = 1; 377 if (stat(fullname, &statb) < 0) { 378 if (errno != ENOENT && errno != ENOTDIR) 379 e = errno; 380 goto loop; 381 } 382 e = EACCES; /* if we fail, this will be the error */ 383 if (!S_ISREG(statb.st_mode)) 384 goto loop; 385 if (pathopt) { /* this is a %func directory */ 386 stalloc(strlen(fullname) + 1); 387 readcmdfile(fullname); 388 if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION) 389 error("%s not defined in %s", name, fullname); 390 stunalloc(fullname); 391 goto success; 392 } 393 #ifdef notdef 394 if (statb.st_uid == geteuid()) { 395 if ((statb.st_mode & 0100) == 0) 396 goto loop; 397 } else if (statb.st_gid == getegid()) { 398 if ((statb.st_mode & 010) == 0) 399 goto loop; 400 } else { 401 if ((statb.st_mode & 01) == 0) 402 goto loop; 403 } 404 #endif 405 TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname)); 406 INTOFF; 407 cmdp = cmdlookup(name, 1); 408 if (cmdp->cmdtype == CMDFUNCTION) 409 cmdp = &loc_cmd; 410 cmdp->cmdtype = CMDNORMAL; 411 cmdp->param.index = idx; 412 INTON; 413 goto success; 414 } 415 416 if (act & DO_ERR) { 417 if (e == ENOENT || e == ENOTDIR) 418 outfmt(out2, "%s: not found\n", name); 419 else 420 outfmt(out2, "%s: %s\n", name, strerror(e)); 421 } 422 entry->cmdtype = CMDUNKNOWN; 423 entry->u.index = 0; 424 return; 425 426 success: 427 if (cd) 428 cmdtable_cd = 1; 429 entry->cmdtype = cmdp->cmdtype; 430 entry->u = cmdp->param; 431 entry->special = cmdp->special; 432 } 433 434 435 436 /* 437 * Search the table of builtin commands. 438 */ 439 440 int 441 find_builtin(const char *name, int *special) 442 { 443 const struct builtincmd *bp; 444 445 for (bp = builtincmd ; bp->name ; bp++) { 446 if (*bp->name == *name && equal(bp->name, name)) { 447 *special = bp->special; 448 return bp->code; 449 } 450 } 451 return -1; 452 } 453 454 455 456 /* 457 * Called when a cd is done. If any entry in cmdtable depends on the current 458 * directory, simply clear cmdtable completely. 459 */ 460 461 void 462 hashcd(void) 463 { 464 if (cmdtable_cd) 465 clearcmdentry(); 466 } 467 468 469 470 /* 471 * Called before PATH is changed. The argument is the new value of PATH; 472 * pathval() still returns the old value at this point. Called with 473 * interrupts off. 474 */ 475 476 void 477 changepath(const char *newval __unused) 478 { 479 clearcmdentry(); 480 } 481 482 483 /* 484 * Clear out command entries. The argument specifies the first entry in 485 * PATH which has changed. 486 */ 487 488 void 489 clearcmdentry(void) 490 { 491 struct tblentry **tblp; 492 struct tblentry **pp; 493 struct tblentry *cmdp; 494 495 INTOFF; 496 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) { 497 pp = tblp; 498 while ((cmdp = *pp) != NULL) { 499 if (cmdp->cmdtype == CMDNORMAL) { 500 *pp = cmdp->next; 501 ckfree(cmdp); 502 } else { 503 pp = &cmdp->next; 504 } 505 } 506 } 507 cmdtable_cd = 0; 508 INTON; 509 } 510 511 512 /* 513 * Locate a command in the command hash table. If "add" is nonzero, 514 * add the command to the table if it is not already present. The 515 * variable "lastcmdentry" is set to point to the address of the link 516 * pointing to the entry, so that delete_cmd_entry can delete the 517 * entry. 518 */ 519 520 static struct tblentry **lastcmdentry; 521 522 523 static struct tblentry * 524 cmdlookup(const char *name, int add) 525 { 526 int hashval; 527 const char *p; 528 struct tblentry *cmdp; 529 struct tblentry **pp; 530 531 p = name; 532 hashval = *p << 4; 533 while (*p) 534 hashval += *p++; 535 hashval &= 0x7FFF; 536 pp = &cmdtable[hashval % CMDTABLESIZE]; 537 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 538 if (equal(cmdp->cmdname, name)) 539 break; 540 pp = &cmdp->next; 541 } 542 if (add && cmdp == NULL) { 543 INTOFF; 544 cmdp = *pp = ckmalloc(sizeof (struct tblentry) 545 + strlen(name) + 1); 546 cmdp->next = NULL; 547 cmdp->cmdtype = CMDUNKNOWN; 548 strcpy(cmdp->cmdname, name); 549 INTON; 550 } 551 lastcmdentry = pp; 552 return cmdp; 553 } 554 555 /* 556 * Delete the command entry returned on the last lookup. 557 */ 558 559 static void 560 delete_cmd_entry(void) 561 { 562 struct tblentry *cmdp; 563 564 INTOFF; 565 cmdp = *lastcmdentry; 566 *lastcmdentry = cmdp->next; 567 ckfree(cmdp); 568 INTON; 569 } 570 571 572 573 /* 574 * Add a new command entry, replacing any existing command entry for 575 * the same name. 576 */ 577 578 static void 579 addcmdentry(const char *name, struct cmdentry *entry) 580 { 581 struct tblentry *cmdp; 582 583 INTOFF; 584 cmdp = cmdlookup(name, 1); 585 if (cmdp->cmdtype == CMDFUNCTION) { 586 unreffunc(cmdp->param.func); 587 } 588 cmdp->cmdtype = entry->cmdtype; 589 cmdp->param = entry->u; 590 INTON; 591 } 592 593 594 /* 595 * Define a shell function. 596 */ 597 598 void 599 defun(const char *name, union node *func) 600 { 601 struct cmdentry entry; 602 603 INTOFF; 604 entry.cmdtype = CMDFUNCTION; 605 entry.u.func = copyfunc(func); 606 addcmdentry(name, &entry); 607 INTON; 608 } 609 610 611 /* 612 * Delete a function if it exists. 613 */ 614 615 int 616 unsetfunc(const char *name) 617 { 618 struct tblentry *cmdp; 619 620 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) { 621 unreffunc(cmdp->param.func); 622 delete_cmd_entry(); 623 return (0); 624 } 625 return (0); 626 } 627 628 629 /* 630 * Check if a function by a certain name exists. 631 */ 632 int 633 isfunc(const char *name) 634 { 635 struct tblentry *cmdp; 636 cmdp = cmdlookup(name, 0); 637 return (cmdp != NULL && cmdp->cmdtype == CMDFUNCTION); 638 } 639 640 641 /* 642 * Shared code for the following builtin commands: 643 * type, command -v, command -V 644 */ 645 646 int 647 typecmd_impl(int argc, char **argv, int cmd, const char *path) 648 { 649 struct cmdentry entry; 650 struct tblentry *cmdp; 651 const char *const *pp; 652 struct alias *ap; 653 int i; 654 int error1 = 0; 655 656 if (path != pathval()) 657 clearcmdentry(); 658 659 for (i = 1; i < argc; i++) { 660 /* First look at the keywords */ 661 for (pp = parsekwd; *pp; pp++) 662 if (**pp == *argv[i] && equal(*pp, argv[i])) 663 break; 664 665 if (*pp) { 666 if (cmd == TYPECMD_SMALLV) 667 out1fmt("%s\n", argv[i]); 668 else 669 out1fmt("%s is a shell keyword\n", argv[i]); 670 continue; 671 } 672 673 /* Then look at the aliases */ 674 if ((ap = lookupalias(argv[i], 1)) != NULL) { 675 if (cmd == TYPECMD_SMALLV) 676 out1fmt("alias %s='%s'\n", argv[i], ap->val); 677 else 678 out1fmt("%s is an alias for %s\n", argv[i], 679 ap->val); 680 continue; 681 } 682 683 /* Then check if it is a tracked alias */ 684 if ((cmdp = cmdlookup(argv[i], 0)) != NULL) { 685 entry.cmdtype = cmdp->cmdtype; 686 entry.u = cmdp->param; 687 entry.special = cmdp->special; 688 } 689 else { 690 /* Finally use brute force */ 691 find_command(argv[i], &entry, 0, path); 692 } 693 694 switch (entry.cmdtype) { 695 case CMDNORMAL: { 696 if (strchr(argv[i], '/') == NULL) { 697 const char *path2 = path; 698 char *name; 699 int j = entry.u.index; 700 do { 701 name = padvance(&path2, argv[i]); 702 stunalloc(name); 703 } while (--j >= 0); 704 if (cmd == TYPECMD_SMALLV) 705 out1fmt("%s\n", name); 706 else 707 out1fmt("%s is%s %s\n", argv[i], 708 (cmdp && cmd == TYPECMD_TYPE) ? 709 " a tracked alias for" : "", 710 name); 711 } else { 712 if (eaccess(argv[i], X_OK) == 0) { 713 if (cmd == TYPECMD_SMALLV) 714 out1fmt("%s\n", argv[i]); 715 else 716 out1fmt("%s is %s\n", argv[i], 717 argv[i]); 718 } else { 719 if (cmd != TYPECMD_SMALLV) 720 outfmt(out2, "%s: %s\n", 721 argv[i], strerror(errno)); 722 error1 |= 127; 723 } 724 } 725 break; 726 } 727 case CMDFUNCTION: 728 if (cmd == TYPECMD_SMALLV) 729 out1fmt("%s\n", argv[i]); 730 else 731 out1fmt("%s is a shell function\n", argv[i]); 732 break; 733 734 case CMDBUILTIN: 735 if (cmd == TYPECMD_SMALLV) 736 out1fmt("%s\n", argv[i]); 737 else if (entry.special) 738 out1fmt("%s is a special shell builtin\n", 739 argv[i]); 740 else 741 out1fmt("%s is a shell builtin\n", argv[i]); 742 break; 743 744 default: 745 if (cmd != TYPECMD_SMALLV) 746 outfmt(out2, "%s: not found\n", argv[i]); 747 error1 |= 127; 748 break; 749 } 750 } 751 752 if (path != pathval()) 753 clearcmdentry(); 754 755 return error1; 756 } 757 758 /* 759 * Locate and print what a word is... 760 */ 761 762 int 763 typecmd(int argc, char **argv) 764 { 765 if (argc > 2 && strcmp(argv[1], "--") == 0) 766 argc--, argv++; 767 return typecmd_impl(argc, argv, TYPECMD_TYPE, bltinlookup("PATH", 1)); 768 } 769