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 1.55 2012/02/11 21:06:45 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 static void addcmdentry(const char *, struct cmdentry *); 103 104 /* 105 * Exec a program. Never returns. If you change this routine, you may 106 * have to change the find_command routine as well. 107 * 108 * The argv array may be changed and element argv[-1] should be writable. 109 */ 110 111 void 112 shellexec(char **argv, char **envp, const char *path, int idx) 113 { 114 char *cmdname; 115 int e; 116 117 if (strchr(argv[0], '/') != NULL) { 118 tryexec(argv[0], argv, envp); 119 e = errno; 120 } else { 121 e = ENOENT; 122 while ((cmdname = padvance(&path, argv[0])) != NULL) { 123 if (--idx < 0 && pathopt == NULL) { 124 tryexec(cmdname, argv, envp); 125 if (errno != ENOENT && errno != ENOTDIR) 126 e = errno; 127 if (e == ENOEXEC) 128 break; 129 } 130 stunalloc(cmdname); 131 } 132 } 133 134 /* Map to POSIX errors */ 135 if (e == ENOENT || e == ENOTDIR) { 136 exerrno = 127; 137 exerror(EXEXEC, "%s: not found", argv[0]); 138 } else { 139 exerrno = 126; 140 exerror(EXEXEC, "%s: %s", argv[0], strerror(e)); 141 } 142 } 143 144 145 static void 146 tryexec(char *cmd, char **argv, char **envp) 147 { 148 int e, in; 149 ssize_t n; 150 char buf[256]; 151 152 execve(cmd, argv, envp); 153 e = errno; 154 if (e == ENOEXEC) { 155 INTOFF; 156 in = open(cmd, O_RDONLY | O_NONBLOCK); 157 if (in != -1) { 158 n = pread(in, buf, sizeof buf, 0); 159 close(in); 160 if (n > 0 && memchr(buf, '\0', n) != NULL) { 161 errno = ENOEXEC; 162 return; 163 } 164 } 165 *argv = cmd; 166 *--argv = __DECONST(char *, _PATH_BSHELL); 167 execve(_PATH_BSHELL, argv, envp); 168 } 169 errno = e; 170 } 171 172 /* 173 * Do a path search. The variable path (passed by reference) should be 174 * set to the start of the path before the first call; padvance will update 175 * this value as it proceeds. Successive calls to padvance will return 176 * the possible path expansions in sequence. If an option (indicated by 177 * a percent sign) appears in the path entry then the global variable 178 * pathopt will be set to point to it; otherwise pathopt will be set to 179 * NULL. 180 */ 181 182 const char *pathopt; 183 184 char * 185 padvance(const char **path, const char *name) 186 { 187 const char *p, *start; 188 char *q; 189 int len; 190 191 if (*path == NULL) 192 return NULL; 193 start = *path; 194 for (p = start; *p && *p != ':' && *p != '%'; p++) 195 ; /* nothing */ 196 len = p - start + strlen(name) + 2; /* "2" is for '/' and '\0' */ 197 STARTSTACKSTR(q); 198 CHECKSTRSPACE(len, q); 199 if (p != start) { 200 memcpy(q, start, p - start); 201 q += p - start; 202 *q++ = '/'; 203 } 204 strcpy(q, name); 205 pathopt = NULL; 206 if (*p == '%') { 207 pathopt = ++p; 208 while (*p && *p != ':') p++; 209 } 210 if (*p == ':') 211 *path = p + 1; 212 else 213 *path = NULL; 214 return stalloc(len); 215 } 216 217 218 219 /*** Command hashing code ***/ 220 221 222 int 223 hashcmd(int argc __unused, char **argv __unused) 224 { 225 struct tblentry **pp; 226 struct tblentry *cmdp; 227 int c; 228 int verbose; 229 struct cmdentry entry; 230 char *name; 231 int errors; 232 233 errors = 0; 234 verbose = 0; 235 while ((c = nextopt("rv")) != '\0') { 236 if (c == 'r') { 237 clearcmdentry(); 238 } else if (c == 'v') { 239 verbose++; 240 } 241 } 242 if (*argptr == NULL) { 243 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { 244 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 245 if (cmdp->cmdtype == CMDNORMAL) 246 printentry(cmdp, verbose); 247 } 248 } 249 return 0; 250 } 251 while ((name = *argptr) != NULL) { 252 if ((cmdp = cmdlookup(name, 0)) != NULL 253 && cmdp->cmdtype == CMDNORMAL) 254 delete_cmd_entry(); 255 find_command(name, &entry, DO_ERR, pathval()); 256 if (entry.cmdtype == CMDUNKNOWN) 257 errors = 1; 258 else if (verbose) { 259 cmdp = cmdlookup(name, 0); 260 if (cmdp != NULL) 261 printentry(cmdp, verbose); 262 else { 263 outfmt(out2, "%s: not found\n", name); 264 errors = 1; 265 } 266 flushall(); 267 } 268 argptr++; 269 } 270 return errors; 271 } 272 273 274 static void 275 printentry(struct tblentry *cmdp, int verbose) 276 { 277 int idx; 278 const char *path; 279 char *name; 280 281 if (cmdp->cmdtype == CMDNORMAL) { 282 idx = cmdp->param.index; 283 path = pathval(); 284 do { 285 name = padvance(&path, cmdp->cmdname); 286 stunalloc(name); 287 } while (--idx >= 0); 288 out1str(name); 289 } else if (cmdp->cmdtype == CMDBUILTIN) { 290 out1fmt("builtin %s", cmdp->cmdname); 291 } else if (cmdp->cmdtype == CMDFUNCTION) { 292 out1fmt("function %s", cmdp->cmdname); 293 if (verbose) { 294 INTOFF; 295 name = commandtext(getfuncnode(cmdp->param.func)); 296 out1c(' '); 297 out1str(name); 298 ckfree(name); 299 INTON; 300 } 301 #ifdef DEBUG 302 } else { 303 error("internal error: cmdtype %d", cmdp->cmdtype); 304 #endif 305 } 306 if (cmdp->rehash) 307 out1c('*'); 308 out1c('\n'); 309 } 310 311 312 313 /* 314 * Resolve a command name. If you change this routine, you may have to 315 * change the shellexec routine as well. 316 */ 317 318 void 319 find_command(const char *name, struct cmdentry *entry, int act, 320 const char *path) 321 { 322 struct tblentry *cmdp, loc_cmd; 323 int idx; 324 int prev; 325 char *fullname; 326 struct stat statb; 327 int e; 328 int i; 329 int spec; 330 331 /* If name contains a slash, don't use the hash table */ 332 if (strchr(name, '/') != NULL) { 333 entry->cmdtype = CMDNORMAL; 334 entry->u.index = 0; 335 return; 336 } 337 338 /* If name is in the table, and not invalidated by cd, we're done */ 339 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0) { 340 if (cmdp->cmdtype == CMDFUNCTION && act & DO_NOFUNC) 341 cmdp = NULL; 342 else 343 goto success; 344 } 345 346 /* Check for builtin next */ 347 if ((i = find_builtin(name, &spec)) >= 0) { 348 INTOFF; 349 cmdp = cmdlookup(name, 1); 350 if (cmdp->cmdtype == CMDFUNCTION) 351 cmdp = &loc_cmd; 352 cmdp->cmdtype = CMDBUILTIN; 353 cmdp->param.index = i; 354 cmdp->special = spec; 355 INTON; 356 goto success; 357 } 358 359 /* We have to search path. */ 360 prev = -1; /* where to start */ 361 if (cmdp) { /* doing a rehash */ 362 if (cmdp->cmdtype == CMDBUILTIN) 363 prev = -1; 364 else 365 prev = cmdp->param.index; 366 } 367 368 e = ENOENT; 369 idx = -1; 370 loop: 371 while ((fullname = padvance(&path, name)) != NULL) { 372 stunalloc(fullname); 373 idx++; 374 if (pathopt) { 375 if (prefix("func", pathopt)) { 376 /* handled below */ 377 } else { 378 goto loop; /* ignore unimplemented options */ 379 } 380 } 381 /* if rehash, don't redo absolute path names */ 382 if (fullname[0] == '/' && idx <= prev) { 383 if (idx < prev) 384 goto loop; 385 TRACE(("searchexec \"%s\": no change\n", name)); 386 goto success; 387 } 388 if (stat(fullname, &statb) < 0) { 389 if (errno != ENOENT && errno != ENOTDIR) 390 e = errno; 391 goto loop; 392 } 393 e = EACCES; /* if we fail, this will be the error */ 394 if (!S_ISREG(statb.st_mode)) 395 goto loop; 396 if (pathopt) { /* this is a %func directory */ 397 stalloc(strlen(fullname) + 1); 398 readcmdfile(fullname); 399 if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION) 400 error("%s not defined in %s", name, fullname); 401 stunalloc(fullname); 402 goto success; 403 } 404 #ifdef notdef 405 if (statb.st_uid == geteuid()) { 406 if ((statb.st_mode & 0100) == 0) 407 goto loop; 408 } else if (statb.st_gid == getegid()) { 409 if ((statb.st_mode & 010) == 0) 410 goto loop; 411 } else { 412 if ((statb.st_mode & 01) == 0) 413 goto loop; 414 } 415 #endif 416 TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname)); 417 INTOFF; 418 cmdp = cmdlookup(name, 1); 419 if (cmdp->cmdtype == CMDFUNCTION) 420 cmdp = &loc_cmd; 421 cmdp->cmdtype = CMDNORMAL; 422 cmdp->param.index = idx; 423 INTON; 424 goto success; 425 } 426 427 /* We failed. If there was an entry for this command, delete it */ 428 if (cmdp && cmdp->cmdtype != CMDFUNCTION) 429 delete_cmd_entry(); 430 if (act & DO_ERR) { 431 if (e == ENOENT || e == ENOTDIR) 432 outfmt(out2, "%s: not found\n", name); 433 else 434 outfmt(out2, "%s: %s\n", name, strerror(e)); 435 } 436 entry->cmdtype = CMDUNKNOWN; 437 entry->u.index = 0; 438 return; 439 440 success: 441 if (cmdp) { 442 cmdp->rehash = 0; 443 entry->cmdtype = cmdp->cmdtype; 444 entry->u = cmdp->param; 445 entry->special = cmdp->special; 446 } else 447 entry->cmdtype = CMDUNKNOWN; 448 } 449 450 451 452 /* 453 * Search the table of builtin commands. 454 */ 455 456 int 457 find_builtin(const char *name, int *special) 458 { 459 const struct builtincmd *bp; 460 461 for (bp = builtincmd ; bp->name ; bp++) { 462 if (*bp->name == *name && equal(bp->name, name)) { 463 *special = bp->special; 464 return bp->code; 465 } 466 } 467 return -1; 468 } 469 470 471 472 /* 473 * Called when a cd is done. Marks all commands so the next time they 474 * are executed they will be rehashed. 475 */ 476 477 void 478 hashcd(void) 479 { 480 struct tblentry **pp; 481 struct tblentry *cmdp; 482 483 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { 484 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 485 if (cmdp->cmdtype == CMDNORMAL) 486 cmdp->rehash = 1; 487 } 488 } 489 } 490 491 492 493 /* 494 * Called before PATH is changed. The argument is the new value of PATH; 495 * pathval() still returns the old value at this point. Called with 496 * interrupts off. 497 */ 498 499 void 500 changepath(const char *newval __unused) 501 { 502 clearcmdentry(); 503 } 504 505 506 /* 507 * Clear out command entries. The argument specifies the first entry in 508 * PATH which has changed. 509 */ 510 511 void 512 clearcmdentry(void) 513 { 514 struct tblentry **tblp; 515 struct tblentry **pp; 516 struct tblentry *cmdp; 517 518 INTOFF; 519 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) { 520 pp = tblp; 521 while ((cmdp = *pp) != NULL) { 522 if (cmdp->cmdtype == CMDNORMAL) { 523 *pp = cmdp->next; 524 ckfree(cmdp); 525 } else { 526 pp = &cmdp->next; 527 } 528 } 529 } 530 INTON; 531 } 532 533 534 /* 535 * Locate a command in the command hash table. If "add" is nonzero, 536 * add the command to the table if it is not already present. The 537 * variable "lastcmdentry" is set to point to the address of the link 538 * pointing to the entry, so that delete_cmd_entry can delete the 539 * entry. 540 */ 541 542 static struct tblentry **lastcmdentry; 543 544 545 static struct tblentry * 546 cmdlookup(const char *name, int add) 547 { 548 int hashval; 549 const char *p; 550 struct tblentry *cmdp; 551 struct tblentry **pp; 552 553 p = name; 554 hashval = *p << 4; 555 while (*p) 556 hashval += *p++; 557 hashval &= 0x7FFF; 558 pp = &cmdtable[hashval % CMDTABLESIZE]; 559 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 560 if (equal(cmdp->cmdname, name)) 561 break; 562 pp = &cmdp->next; 563 } 564 if (add && cmdp == NULL) { 565 INTOFF; 566 cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB 567 + strlen(name) + 1); 568 cmdp->next = NULL; 569 cmdp->cmdtype = CMDUNKNOWN; 570 cmdp->rehash = 0; 571 strcpy(cmdp->cmdname, name); 572 INTON; 573 } 574 lastcmdentry = pp; 575 return cmdp; 576 } 577 578 /* 579 * Delete the command entry returned on the last lookup. 580 */ 581 582 static void 583 delete_cmd_entry(void) 584 { 585 struct tblentry *cmdp; 586 587 INTOFF; 588 cmdp = *lastcmdentry; 589 *lastcmdentry = cmdp->next; 590 ckfree(cmdp); 591 INTON; 592 } 593 594 595 596 /* 597 * Add a new command entry, replacing any existing command entry for 598 * the same name. 599 */ 600 601 static void 602 addcmdentry(const char *name, struct cmdentry *entry) 603 { 604 struct tblentry *cmdp; 605 606 INTOFF; 607 cmdp = cmdlookup(name, 1); 608 if (cmdp->cmdtype == CMDFUNCTION) { 609 unreffunc(cmdp->param.func); 610 } 611 cmdp->cmdtype = entry->cmdtype; 612 cmdp->param = entry->u; 613 INTON; 614 } 615 616 617 /* 618 * Define a shell function. 619 */ 620 621 void 622 defun(const char *name, union node *func) 623 { 624 struct cmdentry entry; 625 626 INTOFF; 627 entry.cmdtype = CMDFUNCTION; 628 entry.u.func = copyfunc(func); 629 addcmdentry(name, &entry); 630 INTON; 631 } 632 633 634 /* 635 * Delete a function if it exists. 636 */ 637 638 int 639 unsetfunc(const char *name) 640 { 641 struct tblentry *cmdp; 642 643 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) { 644 unreffunc(cmdp->param.func); 645 delete_cmd_entry(); 646 } 647 return (0); 648 } 649 650 /* 651 * Shared code for the following builtin commands: 652 * type, command -v, command -V 653 */ 654 655 int 656 typecmd_impl(int argc, char **argv, int cmd, const char *path) 657 { 658 struct cmdentry entry; 659 struct tblentry *cmdp; 660 const char * const *pp; 661 struct alias *ap; 662 int i; 663 int err = 0; 664 665 if (path != pathval()) 666 clearcmdentry(); 667 668 for (i = 1; i < argc; i++) { 669 /* First look at the keywords */ 670 for (pp = parsekwd; *pp; pp++) 671 if (**pp == *argv[i] && equal(*pp, argv[i])) 672 break; 673 674 if (*pp) { 675 if (cmd == TYPECMD_SMALLV) 676 out1fmt("%s\n", argv[i]); 677 else 678 out1fmt("%s is a shell keyword\n", argv[i]); 679 continue; 680 } 681 682 /* Then look at the aliases */ 683 if ((ap = lookupalias(argv[i], 1)) != NULL) { 684 if (cmd == TYPECMD_SMALLV) 685 out1fmt("alias %s='%s'\n", argv[i], ap->val); 686 else 687 out1fmt("%s is an alias for %s\n", argv[i], 688 ap->val); 689 continue; 690 } 691 692 /* Then check if it is a tracked alias */ 693 if ((cmdp = cmdlookup(argv[i], 0)) != NULL) { 694 entry.cmdtype = cmdp->cmdtype; 695 entry.u = cmdp->param; 696 entry.special = cmdp->special; 697 } 698 else { 699 /* Finally use brute force */ 700 find_command(argv[i], &entry, 0, path); 701 } 702 703 switch (entry.cmdtype) { 704 case CMDNORMAL: { 705 if (strchr(argv[i], '/') == NULL) { 706 const char *path2 = path; 707 char *name; 708 int j = entry.u.index; 709 do { 710 name = padvance(&path2, argv[i]); 711 stunalloc(name); 712 } while (--j >= 0); 713 if (cmd == TYPECMD_SMALLV) 714 out1fmt("%s\n", name); 715 else 716 out1fmt("%s is%s %s\n", argv[i], 717 (cmdp && cmd == TYPECMD_TYPE) ? 718 " a tracked alias for" : "", 719 name); 720 } else { 721 if (access(argv[i], X_OK) == 0) { 722 if (cmd == TYPECMD_SMALLV) 723 out1fmt("%s\n", argv[i]); 724 else 725 out1fmt("%s is %s\n", argv[i], 726 argv[i]); 727 } else { 728 if (cmd != TYPECMD_SMALLV) 729 outfmt(out2, "%s: %s\n", 730 argv[i], strerror(errno)); 731 err |= 127; 732 } 733 } 734 break; 735 } 736 case CMDFUNCTION: 737 if (cmd == TYPECMD_SMALLV) 738 out1fmt("%s\n", argv[i]); 739 else 740 out1fmt("%s is a shell function\n", argv[i]); 741 break; 742 743 case CMDBUILTIN: 744 if (cmd == TYPECMD_SMALLV) 745 out1fmt("%s\n", argv[i]); 746 else if (entry.special) 747 out1fmt("%s is a special shell builtin\n", 748 argv[i]); 749 else 750 out1fmt("%s is a shell builtin\n", argv[i]); 751 break; 752 753 default: 754 if (cmd != TYPECMD_SMALLV) 755 outfmt(out2, "%s: not found\n", argv[i]); 756 err |= 127; 757 break; 758 } 759 } 760 761 if (path != pathval()) 762 clearcmdentry(); 763 764 return err; 765 } 766 767 /* 768 * Locate and print what a word is... 769 */ 770 771 int 772 typecmd(int argc, char **argv) 773 { 774 return typecmd_impl(argc, argv, TYPECMD_TYPE, bltinlookup("PATH", 1)); 775 } 776