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 * @(#)exec.c 8.4 (Berkeley) 6/8/95 37 * $FreeBSD: src/bin/sh/exec.c,v 1.52 2011/02/05 14:08:51 jilles Exp $ 38 */ 39 40 #include <sys/types.h> 41 #include <sys/stat.h> 42 #include <unistd.h> 43 #include <fcntl.h> 44 #include <errno.h> 45 #include <paths.h> 46 #include <stdlib.h> 47 48 /* 49 * When commands are first encountered, they are entered in a hash table. 50 * This ensures that a full path search will not have to be done for them 51 * on each invocation. 52 * 53 * We should investigate converting to a linear search, even though that 54 * would make the command name "hash" a misnomer. 55 */ 56 57 #include "shell.h" 58 #include "main.h" 59 #include "nodes.h" 60 #include "parser.h" 61 #include "redir.h" 62 #include "eval.h" 63 #include "exec.h" 64 #include "builtins.h" 65 #include "var.h" 66 #include "options.h" 67 #include "input.h" 68 #include "output.h" 69 #include "syntax.h" 70 #include "memalloc.h" 71 #include "error.h" 72 #include "init.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 #define ARB 1 /* actual size determined at run time */ 81 82 83 84 struct tblentry { 85 struct tblentry *next; /* next entry in hash chain */ 86 union param param; /* definition of builtin function */ 87 int special; /* flag for special builtin commands */ 88 short cmdtype; /* index identifying command */ 89 char rehash; /* if set, cd done since entry created */ 90 char cmdname[ARB]; /* name of command */ 91 }; 92 93 94 static struct tblentry *cmdtable[CMDTABLESIZE]; 95 int exerrno = 0; /* Last exec error */ 96 97 98 static void tryexec(char *, char **, char **); 99 static void printentry(struct tblentry *, int); 100 static struct tblentry *cmdlookup(const char *, int); 101 static void delete_cmd_entry(void); 102 103 /* 104 * Exec a program. Never returns. If you change this routine, you may 105 * have to change the find_command routine as well. 106 * 107 * The argv array may be changed and element argv[-1] should be writable. 108 */ 109 110 void 111 shellexec(char **argv, char **envp, const char *path, int idx) 112 { 113 char *cmdname; 114 int e; 115 116 if (strchr(argv[0], '/') != NULL) { 117 tryexec(argv[0], argv, envp); 118 e = errno; 119 } else { 120 e = ENOENT; 121 while ((cmdname = padvance(&path, argv[0])) != NULL) { 122 if (--idx < 0 && pathopt == NULL) { 123 tryexec(cmdname, argv, envp); 124 if (errno != ENOENT && errno != ENOTDIR) 125 e = errno; 126 if (e == ENOEXEC) 127 break; 128 } 129 stunalloc(cmdname); 130 } 131 } 132 133 /* Map to POSIX errors */ 134 if (e == ENOENT || e == ENOTDIR) { 135 exerrno = 127; 136 exerror(EXEXEC, "%s: not found", argv[0]); 137 } else { 138 exerrno = 126; 139 exerror(EXEXEC, "%s: %s", argv[0], strerror(e)); 140 } 141 } 142 143 144 static void 145 tryexec(char *cmd, char **argv, char **envp) 146 { 147 int e, in; 148 ssize_t n; 149 char buf[256]; 150 151 execve(cmd, argv, envp); 152 e = errno; 153 if (e == ENOEXEC) { 154 INTOFF; 155 in = open(cmd, O_RDONLY | O_NONBLOCK); 156 if (in != -1) { 157 n = pread(in, buf, sizeof buf, 0); 158 close(in); 159 if (n > 0 && memchr(buf, '\0', n) != NULL) { 160 errno = ENOEXEC; 161 return; 162 } 163 } 164 *argv = cmd; 165 *--argv = __DECONST(char *, _PATH_BSHELL); 166 execve(_PATH_BSHELL, argv, envp); 167 } 168 errno = e; 169 } 170 171 /* 172 * Do a path search. The variable path (passed by reference) should be 173 * set to the start of the path before the first call; padvance will update 174 * this value as it proceeds. Successive calls to padvance will return 175 * the possible path expansions in sequence. If an option (indicated by 176 * a percent sign) appears in the path entry then the global variable 177 * pathopt will be set to point to it; otherwise pathopt will be set to 178 * NULL. 179 */ 180 181 const char *pathopt; 182 183 char * 184 padvance(const char **path, const char *name) 185 { 186 const char *p, *start; 187 char *q; 188 int len; 189 190 if (*path == NULL) 191 return NULL; 192 start = *path; 193 for (p = start; *p && *p != ':' && *p != '%'; p++) 194 ; /* nothing */ 195 len = p - start + strlen(name) + 2; /* "2" is for '/' and '\0' */ 196 STARTSTACKSTR(q); 197 CHECKSTRSPACE(len, q); 198 if (p != start) { 199 memcpy(q, start, p - start); 200 q += p - start; 201 *q++ = '/'; 202 } 203 strcpy(q, name); 204 pathopt = NULL; 205 if (*p == '%') { 206 pathopt = ++p; 207 while (*p && *p != ':') p++; 208 } 209 if (*p == ':') 210 *path = p + 1; 211 else 212 *path = NULL; 213 return stalloc(len); 214 } 215 216 217 218 /*** Command hashing code ***/ 219 220 221 int 222 hashcmd(int argc __unused, char **argv __unused) 223 { 224 struct tblentry **pp; 225 struct tblentry *cmdp; 226 int c; 227 int verbose; 228 struct cmdentry entry; 229 char *name; 230 231 verbose = 0; 232 while ((c = nextopt("rv")) != '\0') { 233 if (c == 'r') { 234 clearcmdentry(); 235 } else if (c == 'v') { 236 verbose++; 237 } 238 } 239 if (*argptr == NULL) { 240 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { 241 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 242 if (cmdp->cmdtype == CMDNORMAL) 243 printentry(cmdp, verbose); 244 } 245 } 246 return 0; 247 } 248 while ((name = *argptr) != NULL) { 249 if ((cmdp = cmdlookup(name, 0)) != NULL 250 && cmdp->cmdtype == CMDNORMAL) 251 delete_cmd_entry(); 252 find_command(name, &entry, DO_ERR, pathval()); 253 if (verbose) { 254 if (entry.cmdtype != CMDUNKNOWN) { /* if no error msg */ 255 cmdp = cmdlookup(name, 0); 256 if (cmdp != NULL) 257 printentry(cmdp, verbose); 258 else 259 outfmt(out2, "%s: not found\n", name); 260 } 261 flushall(); 262 } 263 argptr++; 264 } 265 return 0; 266 } 267 268 269 static void 270 printentry(struct tblentry *cmdp, int verbose) 271 { 272 int idx; 273 const char *path; 274 char *name; 275 276 if (cmdp->cmdtype == CMDNORMAL) { 277 idx = cmdp->param.index; 278 path = pathval(); 279 do { 280 name = padvance(&path, cmdp->cmdname); 281 stunalloc(name); 282 } while (--idx >= 0); 283 out1str(name); 284 } else if (cmdp->cmdtype == CMDBUILTIN) { 285 out1fmt("builtin %s", cmdp->cmdname); 286 } else if (cmdp->cmdtype == CMDFUNCTION) { 287 out1fmt("function %s", cmdp->cmdname); 288 if (verbose) { 289 INTOFF; 290 name = commandtext(getfuncnode(cmdp->param.func)); 291 out1c(' '); 292 out1str(name); 293 ckfree(name); 294 INTON; 295 } 296 #ifdef DEBUG 297 } else { 298 error("internal error: cmdtype %d", cmdp->cmdtype); 299 #endif 300 } 301 if (cmdp->rehash) 302 out1c('*'); 303 out1c('\n'); 304 } 305 306 307 308 /* 309 * Resolve a command name. If you change this routine, you may have to 310 * change the shellexec routine as well. 311 */ 312 313 void 314 find_command(const char *name, struct cmdentry *entry, int act, 315 const char *path) 316 { 317 struct tblentry *cmdp, loc_cmd; 318 int idx; 319 int prev; 320 char *fullname; 321 struct stat statb; 322 int e; 323 int i; 324 int spec; 325 326 /* If name contains a slash, don't use the hash table */ 327 if (strchr(name, '/') != NULL) { 328 entry->cmdtype = CMDNORMAL; 329 entry->u.index = 0; 330 return; 331 } 332 333 /* If name is in the table, and not invalidated by cd, we're done */ 334 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0) { 335 if (cmdp->cmdtype == CMDFUNCTION && act & DO_NOFUNC) 336 cmdp = NULL; 337 else 338 goto success; 339 } 340 341 /* Check for builtin next */ 342 if ((i = find_builtin(name, &spec)) >= 0) { 343 INTOFF; 344 cmdp = cmdlookup(name, 1); 345 if (cmdp->cmdtype == CMDFUNCTION) 346 cmdp = &loc_cmd; 347 cmdp->cmdtype = CMDBUILTIN; 348 cmdp->param.index = i; 349 cmdp->special = spec; 350 INTON; 351 goto success; 352 } 353 354 /* We have to search path. */ 355 prev = -1; /* where to start */ 356 if (cmdp) { /* doing a rehash */ 357 if (cmdp->cmdtype == CMDBUILTIN) 358 prev = -1; 359 else 360 prev = cmdp->param.index; 361 } 362 363 e = ENOENT; 364 idx = -1; 365 loop: 366 while ((fullname = padvance(&path, name)) != NULL) { 367 stunalloc(fullname); 368 idx++; 369 if (pathopt) { 370 if (prefix("func", pathopt)) { 371 /* handled below */ 372 } else { 373 goto loop; /* ignore unimplemented options */ 374 } 375 } 376 /* if rehash, don't redo absolute path names */ 377 if (fullname[0] == '/' && idx <= prev) { 378 if (idx < prev) 379 goto loop; 380 TRACE(("searchexec \"%s\": no change\n", name)); 381 goto success; 382 } 383 if (stat(fullname, &statb) < 0) { 384 if (errno != ENOENT && errno != ENOTDIR) 385 e = errno; 386 goto loop; 387 } 388 e = EACCES; /* if we fail, this will be the error */ 389 if (!S_ISREG(statb.st_mode)) 390 goto loop; 391 if (pathopt) { /* this is a %func directory */ 392 stalloc(strlen(fullname) + 1); 393 readcmdfile(fullname); 394 if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION) 395 error("%s not defined in %s", name, fullname); 396 stunalloc(fullname); 397 goto success; 398 } 399 #ifdef notdef 400 if (statb.st_uid == geteuid()) { 401 if ((statb.st_mode & 0100) == 0) 402 goto loop; 403 } else if (statb.st_gid == getegid()) { 404 if ((statb.st_mode & 010) == 0) 405 goto loop; 406 } else { 407 if ((statb.st_mode & 01) == 0) 408 goto loop; 409 } 410 #endif 411 TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname)); 412 INTOFF; 413 cmdp = cmdlookup(name, 1); 414 if (cmdp->cmdtype == CMDFUNCTION) 415 cmdp = &loc_cmd; 416 cmdp->cmdtype = CMDNORMAL; 417 cmdp->param.index = idx; 418 INTON; 419 goto success; 420 } 421 422 /* We failed. If there was an entry for this command, delete it */ 423 if (cmdp && cmdp->cmdtype != CMDFUNCTION) 424 delete_cmd_entry(); 425 if (act & DO_ERR) { 426 if (e == ENOENT || e == ENOTDIR) 427 outfmt(out2, "%s: not found\n", name); 428 else 429 outfmt(out2, "%s: %s\n", name, strerror(e)); 430 } 431 entry->cmdtype = CMDUNKNOWN; 432 entry->u.index = 0; 433 return; 434 435 success: 436 if (cmdp) { 437 cmdp->rehash = 0; 438 entry->cmdtype = cmdp->cmdtype; 439 entry->u = cmdp->param; 440 entry->special = cmdp->special; 441 } else 442 entry->cmdtype = CMDUNKNOWN; 443 } 444 445 446 447 /* 448 * Search the table of builtin commands. 449 */ 450 451 int 452 find_builtin(const char *name, int *special) 453 { 454 const struct builtincmd *bp; 455 456 for (bp = builtincmd ; bp->name ; bp++) { 457 if (*bp->name == *name && equal(bp->name, name)) { 458 *special = bp->special; 459 return bp->code; 460 } 461 } 462 return -1; 463 } 464 465 466 467 /* 468 * Called when a cd is done. Marks all commands so the next time they 469 * are executed they will be rehashed. 470 */ 471 472 void 473 hashcd(void) 474 { 475 struct tblentry **pp; 476 struct tblentry *cmdp; 477 478 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { 479 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 480 if (cmdp->cmdtype == CMDNORMAL) 481 cmdp->rehash = 1; 482 } 483 } 484 } 485 486 487 488 /* 489 * Called before PATH is changed. The argument is the new value of PATH; 490 * pathval() still returns the old value at this point. Called with 491 * interrupts off. 492 */ 493 494 void 495 changepath(const char *newval __unused) 496 { 497 clearcmdentry(); 498 } 499 500 501 /* 502 * Clear out command entries. The argument specifies the first entry in 503 * PATH which has changed. 504 */ 505 506 void 507 clearcmdentry(void) 508 { 509 struct tblentry **tblp; 510 struct tblentry **pp; 511 struct tblentry *cmdp; 512 513 INTOFF; 514 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) { 515 pp = tblp; 516 while ((cmdp = *pp) != NULL) { 517 if (cmdp->cmdtype == CMDNORMAL) { 518 *pp = cmdp->next; 519 ckfree(cmdp); 520 } else { 521 pp = &cmdp->next; 522 } 523 } 524 } 525 INTON; 526 } 527 528 529 /* 530 * Locate a command in the command hash table. If "add" is nonzero, 531 * add the command to the table if it is not already present. The 532 * variable "lastcmdentry" is set to point to the address of the link 533 * pointing to the entry, so that delete_cmd_entry can delete the 534 * entry. 535 */ 536 537 static struct tblentry **lastcmdentry; 538 539 540 static struct tblentry * 541 cmdlookup(const char *name, int add) 542 { 543 int hashval; 544 const char *p; 545 struct tblentry *cmdp; 546 struct tblentry **pp; 547 548 p = name; 549 hashval = *p << 4; 550 while (*p) 551 hashval += *p++; 552 hashval &= 0x7FFF; 553 pp = &cmdtable[hashval % CMDTABLESIZE]; 554 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 555 if (equal(cmdp->cmdname, name)) 556 break; 557 pp = &cmdp->next; 558 } 559 if (add && cmdp == NULL) { 560 INTOFF; 561 cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB 562 + strlen(name) + 1); 563 cmdp->next = NULL; 564 cmdp->cmdtype = CMDUNKNOWN; 565 cmdp->rehash = 0; 566 strcpy(cmdp->cmdname, name); 567 INTON; 568 } 569 lastcmdentry = pp; 570 return cmdp; 571 } 572 573 /* 574 * Delete the command entry returned on the last lookup. 575 */ 576 577 static void 578 delete_cmd_entry(void) 579 { 580 struct tblentry *cmdp; 581 582 INTOFF; 583 cmdp = *lastcmdentry; 584 *lastcmdentry = cmdp->next; 585 ckfree(cmdp); 586 INTON; 587 } 588 589 590 591 /* 592 * Add a new command entry, replacing any existing command entry for 593 * the same name. 594 */ 595 596 void 597 addcmdentry(const char *name, struct cmdentry *entry) 598 { 599 struct tblentry *cmdp; 600 601 INTOFF; 602 cmdp = cmdlookup(name, 1); 603 if (cmdp->cmdtype == CMDFUNCTION) { 604 unreffunc(cmdp->param.func); 605 } 606 cmdp->cmdtype = entry->cmdtype; 607 cmdp->param = entry->u; 608 INTON; 609 } 610 611 612 /* 613 * Define a shell function. 614 */ 615 616 void 617 defun(const char *name, union node *func) 618 { 619 struct cmdentry entry; 620 621 INTOFF; 622 entry.cmdtype = CMDFUNCTION; 623 entry.u.func = copyfunc(func); 624 addcmdentry(name, &entry); 625 INTON; 626 } 627 628 629 /* 630 * Delete a function if it exists. 631 */ 632 633 int 634 unsetfunc(const char *name) 635 { 636 struct tblentry *cmdp; 637 638 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) { 639 unreffunc(cmdp->param.func); 640 delete_cmd_entry(); 641 } 642 return (0); 643 } 644 645 /* 646 * Shared code for the following builtin commands: 647 * type, command -v, command -V 648 */ 649 650 int 651 typecmd_impl(int argc, char **argv, int cmd, const char *path) 652 { 653 struct cmdentry entry; 654 struct tblentry *cmdp; 655 const char * const *pp; 656 struct alias *ap; 657 int i; 658 int err = 0; 659 660 if (path != pathval()) 661 clearcmdentry(); 662 663 for (i = 1; i < argc; i++) { 664 /* First look at the keywords */ 665 for (pp = parsekwd; *pp; pp++) 666 if (**pp == *argv[i] && equal(*pp, argv[i])) 667 break; 668 669 if (*pp) { 670 if (cmd == TYPECMD_SMALLV) 671 out1fmt("%s\n", argv[i]); 672 else 673 out1fmt("%s is a shell keyword\n", argv[i]); 674 continue; 675 } 676 677 /* Then look at the aliases */ 678 if ((ap = lookupalias(argv[i], 1)) != NULL) { 679 if (cmd == TYPECMD_SMALLV) 680 out1fmt("alias %s='%s'\n", argv[i], ap->val); 681 else 682 out1fmt("%s is an alias for %s\n", argv[i], 683 ap->val); 684 continue; 685 } 686 687 /* Then check if it is a tracked alias */ 688 if ((cmdp = cmdlookup(argv[i], 0)) != NULL) { 689 entry.cmdtype = cmdp->cmdtype; 690 entry.u = cmdp->param; 691 entry.special = cmdp->special; 692 } 693 else { 694 /* Finally use brute force */ 695 find_command(argv[i], &entry, 0, path); 696 } 697 698 switch (entry.cmdtype) { 699 case CMDNORMAL: { 700 if (strchr(argv[i], '/') == NULL) { 701 const char *path2 = path; 702 char *name; 703 int j = entry.u.index; 704 do { 705 name = padvance(&path2, argv[i]); 706 stunalloc(name); 707 } while (--j >= 0); 708 if (cmd == TYPECMD_SMALLV) 709 out1fmt("%s\n", name); 710 else 711 out1fmt("%s is%s %s\n", argv[i], 712 (cmdp && cmd == TYPECMD_TYPE) ? 713 " a tracked alias for" : "", 714 name); 715 } else { 716 if (access(argv[i], X_OK) == 0) { 717 if (cmd == TYPECMD_SMALLV) 718 out1fmt("%s\n", argv[i]); 719 else 720 out1fmt("%s is %s\n", argv[i], 721 argv[i]); 722 } else { 723 if (cmd != TYPECMD_SMALLV) 724 outfmt(out2, "%s: %s\n", 725 argv[i], strerror(errno)); 726 err |= 127; 727 } 728 } 729 break; 730 } 731 case CMDFUNCTION: 732 if (cmd == TYPECMD_SMALLV) 733 out1fmt("%s\n", argv[i]); 734 else 735 out1fmt("%s is a shell function\n", argv[i]); 736 break; 737 738 case CMDBUILTIN: 739 if (cmd == TYPECMD_SMALLV) 740 out1fmt("%s\n", argv[i]); 741 else if (entry.special) 742 out1fmt("%s is a special shell builtin\n", 743 argv[i]); 744 else 745 out1fmt("%s is a shell builtin\n", argv[i]); 746 break; 747 748 default: 749 if (cmd != TYPECMD_SMALLV) 750 outfmt(out2, "%s: not found\n", argv[i]); 751 err |= 127; 752 break; 753 } 754 } 755 756 if (path != pathval()) 757 clearcmdentry(); 758 759 return err; 760 } 761 762 /* 763 * Locate and print what a word is... 764 */ 765 766 int 767 typecmd(int argc, char **argv) 768 { 769 return typecmd_impl(argc, argv, TYPECMD_TYPE, bltinlookup("PATH", 1)); 770 } 771