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: head/bin/sh/exec.c 245426 2013-01-14 16:40:50Z jilles $ 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 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 * 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 int errors; 231 232 errors = 0; 233 verbose = 0; 234 while ((c = nextopt("rv")) != '\0') { 235 if (c == 'r') { 236 clearcmdentry(); 237 } else if (c == 'v') { 238 verbose++; 239 } 240 } 241 if (*argptr == NULL) { 242 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { 243 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 244 if (cmdp->cmdtype == CMDNORMAL) 245 printentry(cmdp, verbose); 246 } 247 } 248 return 0; 249 } 250 while ((name = *argptr) != NULL) { 251 if ((cmdp = cmdlookup(name, 0)) != NULL 252 && cmdp->cmdtype == CMDNORMAL) 253 delete_cmd_entry(); 254 find_command(name, &entry, DO_ERR, pathval()); 255 if (entry.cmdtype == CMDUNKNOWN) 256 errors = 1; 257 else if (verbose) { 258 cmdp = cmdlookup(name, 0); 259 if (cmdp != NULL) 260 printentry(cmdp, verbose); 261 else { 262 outfmt(out2, "%s: not found\n", name); 263 errors = 1; 264 } 265 flushall(); 266 } 267 argptr++; 268 } 269 return errors; 270 } 271 272 273 static void 274 printentry(struct tblentry *cmdp, int verbose) 275 { 276 int idx; 277 const char *path; 278 char *name; 279 280 if (cmdp->cmdtype == CMDNORMAL) { 281 idx = cmdp->param.index; 282 path = pathval(); 283 do { 284 name = padvance(&path, cmdp->cmdname); 285 stunalloc(name); 286 } while (--idx >= 0); 287 out1str(name); 288 } else if (cmdp->cmdtype == CMDBUILTIN) { 289 out1fmt("builtin %s", cmdp->cmdname); 290 } else if (cmdp->cmdtype == CMDFUNCTION) { 291 out1fmt("function %s", cmdp->cmdname); 292 if (verbose) { 293 INTOFF; 294 name = commandtext(getfuncnode(cmdp->param.func)); 295 out1c(' '); 296 out1str(name); 297 ckfree(name); 298 INTON; 299 } 300 #ifdef DEBUG 301 } else { 302 error("internal error: cmdtype %d", cmdp->cmdtype); 303 #endif 304 } 305 out1c('\n'); 306 } 307 308 309 310 /* 311 * Resolve a command name. If you change this routine, you may have to 312 * change the shellexec routine as well. 313 */ 314 315 void 316 find_command(const char *name, struct cmdentry *entry, int act, 317 const char *path) 318 { 319 struct tblentry *cmdp, loc_cmd; 320 int idx; 321 char *fullname; 322 struct stat statb; 323 int e; 324 int i; 325 int spec; 326 int cd; 327 328 /* If name contains a slash, don't use the hash table */ 329 if (strchr(name, '/') != NULL) { 330 entry->cmdtype = CMDNORMAL; 331 entry->u.index = 0; 332 return; 333 } 334 335 cd = 0; 336 337 /* If name is in the table, and not invalidated by cd, we're done */ 338 if ((cmdp = cmdlookup(name, 0)) != NULL) { 339 if (cmdp->cmdtype == CMDFUNCTION && act & DO_NOFUNC) 340 cmdp = NULL; 341 else 342 goto success; 343 } 344 345 /* Check for builtin next */ 346 if ((i = find_builtin(name, &spec)) >= 0) { 347 INTOFF; 348 cmdp = cmdlookup(name, 1); 349 if (cmdp->cmdtype == CMDFUNCTION) 350 cmdp = &loc_cmd; 351 cmdp->cmdtype = CMDBUILTIN; 352 cmdp->param.index = i; 353 cmdp->special = spec; 354 INTON; 355 goto success; 356 } 357 358 /* We have to search path. */ 359 360 e = ENOENT; 361 idx = -1; 362 loop: 363 while ((fullname = padvance(&path, name)) != NULL) { 364 stunalloc(fullname); 365 idx++; 366 if (pathopt) { 367 if (prefix("func", pathopt)) { 368 /* handled below */ 369 } else { 370 goto loop; /* ignore unimplemented options */ 371 } 372 } 373 if (fullname[0] != '/') 374 cd = 1; 375 if (stat(fullname, &statb) < 0) { 376 if (errno != ENOENT && errno != ENOTDIR) 377 e = errno; 378 goto loop; 379 } 380 e = EACCES; /* if we fail, this will be the error */ 381 if (!S_ISREG(statb.st_mode)) 382 goto loop; 383 if (pathopt) { /* this is a %func directory */ 384 stalloc(strlen(fullname) + 1); 385 readcmdfile(fullname); 386 if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION) 387 error("%s not defined in %s", name, fullname); 388 stunalloc(fullname); 389 goto success; 390 } 391 #ifdef notdef 392 if (statb.st_uid == geteuid()) { 393 if ((statb.st_mode & 0100) == 0) 394 goto loop; 395 } else if (statb.st_gid == getegid()) { 396 if ((statb.st_mode & 010) == 0) 397 goto loop; 398 } else { 399 if ((statb.st_mode & 01) == 0) 400 goto loop; 401 } 402 #endif 403 TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname)); 404 INTOFF; 405 cmdp = cmdlookup(name, 1); 406 if (cmdp->cmdtype == CMDFUNCTION) 407 cmdp = &loc_cmd; 408 cmdp->cmdtype = CMDNORMAL; 409 cmdp->param.index = idx; 410 INTON; 411 goto success; 412 } 413 414 if (act & DO_ERR) { 415 if (e == ENOENT || e == ENOTDIR) 416 outfmt(out2, "%s: not found\n", name); 417 else 418 outfmt(out2, "%s: %s\n", name, strerror(e)); 419 } 420 entry->cmdtype = CMDUNKNOWN; 421 entry->u.index = 0; 422 return; 423 424 success: 425 if (cmdp) { 426 if (cd) 427 cmdtable_cd = 1; 428 entry->cmdtype = cmdp->cmdtype; 429 entry->u = cmdp->param; 430 entry->special = cmdp->special; 431 } else 432 entry->cmdtype = CMDUNKNOWN; 433 } 434 435 436 437 /* 438 * Search the table of builtin commands. 439 */ 440 441 int 442 find_builtin(const char *name, int *special) 443 { 444 const struct builtincmd *bp; 445 446 for (bp = builtincmd ; bp->name ; bp++) { 447 if (*bp->name == *name && equal(bp->name, name)) { 448 *special = bp->special; 449 return bp->code; 450 } 451 } 452 return -1; 453 } 454 455 456 457 /* 458 * Called when a cd is done. If any entry in cmdtable depends on the current 459 * directory, simply clear cmdtable completely. 460 */ 461 462 void 463 hashcd(void) 464 { 465 if (cmdtable_cd) 466 clearcmdentry(); 467 } 468 469 470 471 /* 472 * Called before PATH is changed. The argument is the new value of PATH; 473 * pathval() still returns the old value at this point. Called with 474 * interrupts off. 475 */ 476 477 void 478 changepath(const char *newval __unused) 479 { 480 clearcmdentry(); 481 } 482 483 484 /* 485 * Clear out command entries. The argument specifies the first entry in 486 * PATH which has changed. 487 */ 488 489 void 490 clearcmdentry(void) 491 { 492 struct tblentry **tblp; 493 struct tblentry **pp; 494 struct tblentry *cmdp; 495 496 INTOFF; 497 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) { 498 pp = tblp; 499 while ((cmdp = *pp) != NULL) { 500 if (cmdp->cmdtype == CMDNORMAL) { 501 *pp = cmdp->next; 502 ckfree(cmdp); 503 } else { 504 pp = &cmdp->next; 505 } 506 } 507 } 508 cmdtable_cd = 0; 509 INTON; 510 } 511 512 513 /* 514 * Locate a command in the command hash table. If "add" is nonzero, 515 * add the command to the table if it is not already present. The 516 * variable "lastcmdentry" is set to point to the address of the link 517 * pointing to the entry, so that delete_cmd_entry can delete the 518 * entry. 519 */ 520 521 static struct tblentry **lastcmdentry; 522 523 524 static struct tblentry * 525 cmdlookup(const char *name, int add) 526 { 527 int hashval; 528 const char *p; 529 struct tblentry *cmdp; 530 struct tblentry **pp; 531 532 p = name; 533 hashval = *p << 4; 534 while (*p) 535 hashval += *p++; 536 hashval &= 0x7FFF; 537 pp = &cmdtable[hashval % CMDTABLESIZE]; 538 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 539 if (equal(cmdp->cmdname, name)) 540 break; 541 pp = &cmdp->next; 542 } 543 if (add && cmdp == NULL) { 544 INTOFF; 545 cmdp = *pp = ckmalloc(sizeof (struct tblentry) 546 + strlen(name) + 1); 547 cmdp->next = NULL; 548 cmdp->cmdtype = CMDUNKNOWN; 549 strcpy(cmdp->cmdname, name); 550 INTON; 551 } 552 lastcmdentry = pp; 553 return cmdp; 554 } 555 556 /* 557 * Delete the command entry returned on the last lookup. 558 */ 559 560 static void 561 delete_cmd_entry(void) 562 { 563 struct tblentry *cmdp; 564 565 INTOFF; 566 cmdp = *lastcmdentry; 567 *lastcmdentry = cmdp->next; 568 ckfree(cmdp); 569 INTON; 570 } 571 572 573 574 /* 575 * Add a new command entry, replacing any existing command entry for 576 * the same name. 577 */ 578 579 static void 580 addcmdentry(const char *name, struct cmdentry *entry) 581 { 582 struct tblentry *cmdp; 583 584 INTOFF; 585 cmdp = cmdlookup(name, 1); 586 if (cmdp->cmdtype == CMDFUNCTION) { 587 unreffunc(cmdp->param.func); 588 } 589 cmdp->cmdtype = entry->cmdtype; 590 cmdp->param = entry->u; 591 INTON; 592 } 593 594 595 /* 596 * Define a shell function. 597 */ 598 599 void 600 defun(const char *name, union node *func) 601 { 602 struct cmdentry entry; 603 604 INTOFF; 605 entry.cmdtype = CMDFUNCTION; 606 entry.u.func = copyfunc(func); 607 addcmdentry(name, &entry); 608 INTON; 609 } 610 611 612 /* 613 * Delete a function if it exists. 614 */ 615 616 int 617 unsetfunc(const char *name) 618 { 619 struct tblentry *cmdp; 620 621 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) { 622 unreffunc(cmdp->param.func); 623 delete_cmd_entry(); 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 err = 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 (access(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 err |= 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 err |= 127; 748 break; 749 } 750 } 751 752 if (path != pathval()) 753 clearcmdentry(); 754 755 return err; 756 } 757 758 /* 759 * Locate and print what a word is... 760 */ 761 762 int 763 typecmd(int argc, char **argv) 764 { 765 return typecmd_impl(argc, argv, TYPECMD_TYPE, bltinlookup("PATH", 1)); 766 } 767