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 1.53 2012/01/01 22:17:12 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; 231 232 verbose = 0; 233 while ((c = nextopt("rv")) != '\0') { 234 if (c == 'r') { 235 clearcmdentry(); 236 } else if (c == 'v') { 237 verbose++; 238 } 239 } 240 if (*argptr == NULL) { 241 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { 242 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 243 if (cmdp->cmdtype == CMDNORMAL) 244 printentry(cmdp, verbose); 245 } 246 } 247 return 0; 248 } 249 while ((name = *argptr) != NULL) { 250 if ((cmdp = cmdlookup(name, 0)) != NULL 251 && cmdp->cmdtype == CMDNORMAL) 252 delete_cmd_entry(); 253 find_command(name, &entry, DO_ERR, pathval()); 254 if (verbose) { 255 if (entry.cmdtype != CMDUNKNOWN) { /* if no error msg */ 256 cmdp = cmdlookup(name, 0); 257 if (cmdp != NULL) 258 printentry(cmdp, verbose); 259 else 260 outfmt(out2, "%s: not found\n", name); 261 } 262 flushall(); 263 } 264 argptr++; 265 } 266 return 0; 267 } 268 269 270 static void 271 printentry(struct tblentry *cmdp, int verbose) 272 { 273 int idx; 274 const char *path; 275 char *name; 276 277 if (cmdp->cmdtype == CMDNORMAL) { 278 idx = cmdp->param.index; 279 path = pathval(); 280 do { 281 name = padvance(&path, cmdp->cmdname); 282 stunalloc(name); 283 } while (--idx >= 0); 284 out1str(name); 285 } else if (cmdp->cmdtype == CMDBUILTIN) { 286 out1fmt("builtin %s", cmdp->cmdname); 287 } else if (cmdp->cmdtype == CMDFUNCTION) { 288 out1fmt("function %s", cmdp->cmdname); 289 if (verbose) { 290 INTOFF; 291 name = commandtext(getfuncnode(cmdp->param.func)); 292 out1c(' '); 293 out1str(name); 294 ckfree(name); 295 INTON; 296 } 297 #ifdef DEBUG 298 } else { 299 error("internal error: cmdtype %d", cmdp->cmdtype); 300 #endif 301 } 302 if (cmdp->rehash) 303 out1c('*'); 304 out1c('\n'); 305 } 306 307 308 309 /* 310 * Resolve a command name. If you change this routine, you may have to 311 * change the shellexec routine as well. 312 */ 313 314 void 315 find_command(const char *name, struct cmdentry *entry, int act, 316 const char *path) 317 { 318 struct tblentry *cmdp, loc_cmd; 319 int idx; 320 int prev; 321 char *fullname; 322 struct stat statb; 323 int e; 324 int i; 325 int spec; 326 327 /* If name contains a slash, don't use the hash table */ 328 if (strchr(name, '/') != NULL) { 329 entry->cmdtype = CMDNORMAL; 330 entry->u.index = 0; 331 return; 332 } 333 334 /* If name is in the table, and not invalidated by cd, we're done */ 335 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0) { 336 if (cmdp->cmdtype == CMDFUNCTION && act & DO_NOFUNC) 337 cmdp = NULL; 338 else 339 goto success; 340 } 341 342 /* Check for builtin next */ 343 if ((i = find_builtin(name, &spec)) >= 0) { 344 INTOFF; 345 cmdp = cmdlookup(name, 1); 346 if (cmdp->cmdtype == CMDFUNCTION) 347 cmdp = &loc_cmd; 348 cmdp->cmdtype = CMDBUILTIN; 349 cmdp->param.index = i; 350 cmdp->special = spec; 351 INTON; 352 goto success; 353 } 354 355 /* We have to search path. */ 356 prev = -1; /* where to start */ 357 if (cmdp) { /* doing a rehash */ 358 if (cmdp->cmdtype == CMDBUILTIN) 359 prev = -1; 360 else 361 prev = cmdp->param.index; 362 } 363 364 e = ENOENT; 365 idx = -1; 366 loop: 367 while ((fullname = padvance(&path, name)) != NULL) { 368 stunalloc(fullname); 369 idx++; 370 if (pathopt) { 371 if (prefix("func", pathopt)) { 372 /* handled below */ 373 } else { 374 goto loop; /* ignore unimplemented options */ 375 } 376 } 377 /* if rehash, don't redo absolute path names */ 378 if (fullname[0] == '/' && idx <= prev) { 379 if (idx < prev) 380 goto loop; 381 TRACE(("searchexec \"%s\": no change\n", name)); 382 goto success; 383 } 384 if (stat(fullname, &statb) < 0) { 385 if (errno != ENOENT && errno != ENOTDIR) 386 e = errno; 387 goto loop; 388 } 389 e = EACCES; /* if we fail, this will be the error */ 390 if (!S_ISREG(statb.st_mode)) 391 goto loop; 392 if (pathopt) { /* this is a %func directory */ 393 stalloc(strlen(fullname) + 1); 394 readcmdfile(fullname); 395 if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION) 396 error("%s not defined in %s", name, fullname); 397 stunalloc(fullname); 398 goto success; 399 } 400 #ifdef notdef 401 if (statb.st_uid == geteuid()) { 402 if ((statb.st_mode & 0100) == 0) 403 goto loop; 404 } else if (statb.st_gid == getegid()) { 405 if ((statb.st_mode & 010) == 0) 406 goto loop; 407 } else { 408 if ((statb.st_mode & 01) == 0) 409 goto loop; 410 } 411 #endif 412 TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname)); 413 INTOFF; 414 cmdp = cmdlookup(name, 1); 415 if (cmdp->cmdtype == CMDFUNCTION) 416 cmdp = &loc_cmd; 417 cmdp->cmdtype = CMDNORMAL; 418 cmdp->param.index = idx; 419 INTON; 420 goto success; 421 } 422 423 /* We failed. If there was an entry for this command, delete it */ 424 if (cmdp && cmdp->cmdtype != CMDFUNCTION) 425 delete_cmd_entry(); 426 if (act & DO_ERR) { 427 if (e == ENOENT || e == ENOTDIR) 428 outfmt(out2, "%s: not found\n", name); 429 else 430 outfmt(out2, "%s: %s\n", name, strerror(e)); 431 } 432 entry->cmdtype = CMDUNKNOWN; 433 entry->u.index = 0; 434 return; 435 436 success: 437 if (cmdp) { 438 cmdp->rehash = 0; 439 entry->cmdtype = cmdp->cmdtype; 440 entry->u = cmdp->param; 441 entry->special = cmdp->special; 442 } else 443 entry->cmdtype = CMDUNKNOWN; 444 } 445 446 447 448 /* 449 * Search the table of builtin commands. 450 */ 451 452 int 453 find_builtin(const char *name, int *special) 454 { 455 const struct builtincmd *bp; 456 457 for (bp = builtincmd ; bp->name ; bp++) { 458 if (*bp->name == *name && equal(bp->name, name)) { 459 *special = bp->special; 460 return bp->code; 461 } 462 } 463 return -1; 464 } 465 466 467 468 /* 469 * Called when a cd is done. Marks all commands so the next time they 470 * are executed they will be rehashed. 471 */ 472 473 void 474 hashcd(void) 475 { 476 struct tblentry **pp; 477 struct tblentry *cmdp; 478 479 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { 480 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 481 if (cmdp->cmdtype == CMDNORMAL) 482 cmdp->rehash = 1; 483 } 484 } 485 } 486 487 488 489 /* 490 * Called before PATH is changed. The argument is the new value of PATH; 491 * pathval() still returns the old value at this point. Called with 492 * interrupts off. 493 */ 494 495 void 496 changepath(const char *newval __unused) 497 { 498 clearcmdentry(); 499 } 500 501 502 /* 503 * Clear out command entries. The argument specifies the first entry in 504 * PATH which has changed. 505 */ 506 507 void 508 clearcmdentry(void) 509 { 510 struct tblentry **tblp; 511 struct tblentry **pp; 512 struct tblentry *cmdp; 513 514 INTOFF; 515 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) { 516 pp = tblp; 517 while ((cmdp = *pp) != NULL) { 518 if (cmdp->cmdtype == CMDNORMAL) { 519 *pp = cmdp->next; 520 ckfree(cmdp); 521 } else { 522 pp = &cmdp->next; 523 } 524 } 525 } 526 INTON; 527 } 528 529 530 /* 531 * Locate a command in the command hash table. If "add" is nonzero, 532 * add the command to the table if it is not already present. The 533 * variable "lastcmdentry" is set to point to the address of the link 534 * pointing to the entry, so that delete_cmd_entry can delete the 535 * entry. 536 */ 537 538 static struct tblentry **lastcmdentry; 539 540 541 static struct tblentry * 542 cmdlookup(const char *name, int add) 543 { 544 int hashval; 545 const char *p; 546 struct tblentry *cmdp; 547 struct tblentry **pp; 548 549 p = name; 550 hashval = *p << 4; 551 while (*p) 552 hashval += *p++; 553 hashval &= 0x7FFF; 554 pp = &cmdtable[hashval % CMDTABLESIZE]; 555 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 556 if (equal(cmdp->cmdname, name)) 557 break; 558 pp = &cmdp->next; 559 } 560 if (add && cmdp == NULL) { 561 INTOFF; 562 cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB 563 + strlen(name) + 1); 564 cmdp->next = NULL; 565 cmdp->cmdtype = CMDUNKNOWN; 566 cmdp->rehash = 0; 567 strcpy(cmdp->cmdname, name); 568 INTON; 569 } 570 lastcmdentry = pp; 571 return cmdp; 572 } 573 574 /* 575 * Delete the command entry returned on the last lookup. 576 */ 577 578 static void 579 delete_cmd_entry(void) 580 { 581 struct tblentry *cmdp; 582 583 INTOFF; 584 cmdp = *lastcmdentry; 585 *lastcmdentry = cmdp->next; 586 ckfree(cmdp); 587 INTON; 588 } 589 590 591 592 /* 593 * Add a new command entry, replacing any existing command entry for 594 * the same name. 595 */ 596 597 static void 598 addcmdentry(const char *name, struct cmdentry *entry) 599 { 600 struct tblentry *cmdp; 601 602 INTOFF; 603 cmdp = cmdlookup(name, 1); 604 if (cmdp->cmdtype == CMDFUNCTION) { 605 unreffunc(cmdp->param.func); 606 } 607 cmdp->cmdtype = entry->cmdtype; 608 cmdp->param = entry->u; 609 INTON; 610 } 611 612 613 /* 614 * Define a shell function. 615 */ 616 617 void 618 defun(const char *name, union node *func) 619 { 620 struct cmdentry entry; 621 622 INTOFF; 623 entry.cmdtype = CMDFUNCTION; 624 entry.u.func = copyfunc(func); 625 addcmdentry(name, &entry); 626 INTON; 627 } 628 629 630 /* 631 * Delete a function if it exists. 632 */ 633 634 int 635 unsetfunc(const char *name) 636 { 637 struct tblentry *cmdp; 638 639 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) { 640 unreffunc(cmdp->param.func); 641 delete_cmd_entry(); 642 } 643 return (0); 644 } 645 646 /* 647 * Shared code for the following builtin commands: 648 * type, command -v, command -V 649 */ 650 651 int 652 typecmd_impl(int argc, char **argv, int cmd, const char *path) 653 { 654 struct cmdentry entry; 655 struct tblentry *cmdp; 656 const char * const *pp; 657 struct alias *ap; 658 int i; 659 int err = 0; 660 661 if (path != pathval()) 662 clearcmdentry(); 663 664 for (i = 1; i < argc; i++) { 665 /* First look at the keywords */ 666 for (pp = parsekwd; *pp; pp++) 667 if (**pp == *argv[i] && equal(*pp, argv[i])) 668 break; 669 670 if (*pp) { 671 if (cmd == TYPECMD_SMALLV) 672 out1fmt("%s\n", argv[i]); 673 else 674 out1fmt("%s is a shell keyword\n", argv[i]); 675 continue; 676 } 677 678 /* Then look at the aliases */ 679 if ((ap = lookupalias(argv[i], 1)) != NULL) { 680 if (cmd == TYPECMD_SMALLV) 681 out1fmt("alias %s='%s'\n", argv[i], ap->val); 682 else 683 out1fmt("%s is an alias for %s\n", argv[i], 684 ap->val); 685 continue; 686 } 687 688 /* Then check if it is a tracked alias */ 689 if ((cmdp = cmdlookup(argv[i], 0)) != NULL) { 690 entry.cmdtype = cmdp->cmdtype; 691 entry.u = cmdp->param; 692 entry.special = cmdp->special; 693 } 694 else { 695 /* Finally use brute force */ 696 find_command(argv[i], &entry, 0, path); 697 } 698 699 switch (entry.cmdtype) { 700 case CMDNORMAL: { 701 if (strchr(argv[i], '/') == NULL) { 702 const char *path2 = path; 703 char *name; 704 int j = entry.u.index; 705 do { 706 name = padvance(&path2, argv[i]); 707 stunalloc(name); 708 } while (--j >= 0); 709 if (cmd == TYPECMD_SMALLV) 710 out1fmt("%s\n", name); 711 else 712 out1fmt("%s is%s %s\n", argv[i], 713 (cmdp && cmd == TYPECMD_TYPE) ? 714 " a tracked alias for" : "", 715 name); 716 } else { 717 if (access(argv[i], X_OK) == 0) { 718 if (cmd == TYPECMD_SMALLV) 719 out1fmt("%s\n", argv[i]); 720 else 721 out1fmt("%s is %s\n", argv[i], 722 argv[i]); 723 } else { 724 if (cmd != TYPECMD_SMALLV) 725 outfmt(out2, "%s: %s\n", 726 argv[i], strerror(errno)); 727 err |= 127; 728 } 729 } 730 break; 731 } 732 case CMDFUNCTION: 733 if (cmd == TYPECMD_SMALLV) 734 out1fmt("%s\n", argv[i]); 735 else 736 out1fmt("%s is a shell function\n", argv[i]); 737 break; 738 739 case CMDBUILTIN: 740 if (cmd == TYPECMD_SMALLV) 741 out1fmt("%s\n", argv[i]); 742 else if (entry.special) 743 out1fmt("%s is a special shell builtin\n", 744 argv[i]); 745 else 746 out1fmt("%s is a shell builtin\n", argv[i]); 747 break; 748 749 default: 750 if (cmd != TYPECMD_SMALLV) 751 outfmt(out2, "%s: not found\n", argv[i]); 752 err |= 127; 753 break; 754 } 755 } 756 757 if (path != pathval()) 758 clearcmdentry(); 759 760 return err; 761 } 762 763 /* 764 * Locate and print what a word is... 765 */ 766 767 int 768 typecmd(int argc, char **argv) 769 { 770 return typecmd_impl(argc, argv, TYPECMD_TYPE, bltinlookup("PATH", 1)); 771 } 772