1 /*- 2 * Copyright (c) 1991 The Regents of the University of California. 3 * 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 37 #ifndef lint 38 static char sccsid[] = "@(#)exec.c 5.2 (Berkeley) 3/13/91"; 39 #endif /* not lint */ 40 41 /* 42 * When commands are first encountered, they are entered in a hash table. 43 * This ensures that a full path search will not have to be done for them 44 * on each invocation. 45 * 46 * We should investigate converting to a linear search, even though that 47 * would make the command name "hash" a misnomer. 48 */ 49 50 #include "shell.h" 51 #include "main.h" 52 #include "nodes.h" 53 #include "parser.h" 54 #include "redir.h" 55 #include "eval.h" 56 #include "exec.h" 57 #include "builtins.h" 58 #include "var.h" 59 #include "options.h" 60 #include "input.h" 61 #include "output.h" 62 #include "syntax.h" 63 #include "memalloc.h" 64 #include "error.h" 65 #include "init.h" 66 #include "mystring.h" 67 #include <sys/types.h> 68 #include <sys/stat.h> 69 #include <fcntl.h> 70 #include <errno.h> 71 72 73 #define CMDTABLESIZE 31 /* should be prime */ 74 #define ARB 1 /* actual size determined at run time */ 75 76 77 78 struct tblentry { 79 struct tblentry *next; /* next entry in hash chain */ 80 union param param; /* definition of builtin function */ 81 short cmdtype; /* index identifying command */ 82 char rehash; /* if set, cd done since entry created */ 83 char cmdname[ARB]; /* name of command */ 84 }; 85 86 87 STATIC struct tblentry *cmdtable[CMDTABLESIZE]; 88 STATIC int builtinloc = -1; /* index in path of %builtin, or -1 */ 89 90 91 #ifdef __STDC__ 92 STATIC void tryexec(char *, char **, char **); 93 STATIC void execinterp(char **, char **); 94 STATIC void printentry(struct tblentry *); 95 STATIC void clearcmdentry(int); 96 STATIC struct tblentry *cmdlookup(char *, int); 97 STATIC void delete_cmd_entry(void); 98 #else 99 STATIC void tryexec(); 100 STATIC void execinterp(); 101 STATIC void printentry(); 102 STATIC void clearcmdentry(); 103 STATIC struct tblentry *cmdlookup(); 104 STATIC void delete_cmd_entry(); 105 #endif 106 107 108 109 /* 110 * Exec a program. Never returns. If you change this routine, you may 111 * have to change the find_command routine as well. 112 */ 113 114 void 115 shellexec(argv, envp, path, index) 116 char **argv, **envp; 117 char *path; 118 { 119 char *cmdname; 120 int e; 121 122 if (strchr(argv[0], '/') != NULL) { 123 tryexec(argv[0], argv, envp); 124 e = errno; 125 } else { 126 e = ENOENT; 127 while ((cmdname = padvance(&path, argv[0])) != NULL) { 128 if (--index < 0 && pathopt == NULL) { 129 tryexec(cmdname, argv, envp); 130 if (errno != ENOENT && errno != ENOTDIR) 131 e = errno; 132 } 133 stunalloc(cmdname); 134 } 135 } 136 error2(argv[0], errmsg(e, E_EXEC)); 137 } 138 139 140 STATIC void 141 tryexec(cmd, argv, envp) 142 char *cmd; 143 char **argv; 144 char **envp; 145 { 146 int e; 147 char *p; 148 149 #ifdef SYSV 150 do { 151 execve(cmd, argv, envp); 152 } while (errno == EINTR); 153 #else 154 execve(cmd, argv, envp); 155 #endif 156 e = errno; 157 if (e == ENOEXEC) { 158 initshellproc(); 159 setinputfile(cmd, 0); 160 commandname = arg0 = savestr(argv[0]); 161 #ifndef BSD 162 pgetc(); pungetc(); /* fill up input buffer */ 163 p = parsenextc; 164 if (parsenleft > 2 && p[0] == '#' && p[1] == '!') { 165 argv[0] = cmd; 166 execinterp(argv, envp); 167 } 168 #endif 169 setparam(argv + 1); 170 exraise(EXSHELLPROC); 171 /*NOTREACHED*/ 172 } 173 errno = e; 174 } 175 176 177 #ifndef BSD 178 /* 179 * Execute an interpreter introduced by "#!", for systems where this 180 * feature has not been built into the kernel. If the interpreter is 181 * the shell, return (effectively ignoring the "#!"). If the execution 182 * of the interpreter fails, exit. 183 * 184 * This code peeks inside the input buffer in order to avoid actually 185 * reading any input. It would benefit from a rewrite. 186 */ 187 188 #define NEWARGS 5 189 190 STATIC void 191 execinterp(argv, envp) 192 char **argv, **envp; 193 { 194 int n; 195 char *inp; 196 char *outp; 197 char c; 198 char *p; 199 char **ap; 200 char *newargs[NEWARGS]; 201 int i; 202 char **ap2; 203 char **new; 204 205 n = parsenleft - 2; 206 inp = parsenextc + 2; 207 ap = newargs; 208 for (;;) { 209 while (--n >= 0 && (*inp == ' ' || *inp == '\t')) 210 inp++; 211 if (n < 0) 212 goto bad; 213 if ((c = *inp++) == '\n') 214 break; 215 if (ap == &newargs[NEWARGS]) 216 bad: error("Bad #! line"); 217 STARTSTACKSTR(outp); 218 do { 219 STPUTC(c, outp); 220 } while (--n >= 0 && (c = *inp++) != ' ' && c != '\t' && c != '\n'); 221 STPUTC('\0', outp); 222 n++, inp--; 223 *ap++ = grabstackstr(outp); 224 } 225 if (ap == newargs + 1) { /* if no args, maybe no exec is needed */ 226 p = newargs[0]; 227 for (;;) { 228 if (equal(p, "sh") || equal(p, "ash")) { 229 return; 230 } 231 while (*p != '/') { 232 if (*p == '\0') 233 goto break2; 234 p++; 235 } 236 p++; 237 } 238 break2:; 239 } 240 i = (char *)ap - (char *)newargs; /* size in bytes */ 241 if (i == 0) 242 error("Bad #! line"); 243 for (ap2 = argv ; *ap2++ != NULL ; ); 244 new = ckmalloc(i + ((char *)ap2 - (char *)argv)); 245 ap = newargs, ap2 = new; 246 while ((i -= sizeof (char **)) >= 0) 247 *ap2++ = *ap++; 248 ap = argv; 249 while (*ap2++ = *ap++); 250 shellexec(new, envp, pathval(), 0); 251 } 252 #endif 253 254 255 256 /* 257 * Do a path search. The variable path (passed by reference) should be 258 * set to the start of the path before the first call; padvance will update 259 * this value as it proceeds. Successive calls to padvance will return 260 * the possible path expansions in sequence. If an option (indicated by 261 * a percent sign) appears in the path entry then the global variable 262 * pathopt will be set to point to it; otherwise pathopt will be set to 263 * NULL. 264 */ 265 266 char *pathopt; 267 268 char * 269 padvance(path, name) 270 char **path; 271 char *name; 272 { 273 register char *p, *q; 274 char *start; 275 int len; 276 277 if (*path == NULL) 278 return NULL; 279 start = *path; 280 for (p = start ; *p && *p != ':' && *p != '%' ; p++); 281 len = p - start + strlen(name) + 2; /* "2" is for '/' and '\0' */ 282 while (stackblocksize() < len) 283 growstackblock(); 284 q = stackblock(); 285 if (p != start) { 286 bcopy(start, q, p - start); 287 q += p - start; 288 *q++ = '/'; 289 } 290 strcpy(q, name); 291 pathopt = NULL; 292 if (*p == '%') { 293 pathopt = ++p; 294 while (*p && *p != ':') p++; 295 } 296 if (*p == ':') 297 *path = p + 1; 298 else 299 *path = NULL; 300 return stalloc(len); 301 } 302 303 304 305 /*** Command hashing code ***/ 306 307 308 hashcmd(argc, argv) char **argv; { 309 struct tblentry **pp; 310 struct tblentry *cmdp; 311 int c; 312 int verbose; 313 struct cmdentry entry; 314 char *name; 315 316 if (argc <= 1) { 317 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { 318 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 319 printentry(cmdp); 320 } 321 } 322 return 0; 323 } 324 verbose = 0; 325 while ((c = nextopt("rv")) != '\0') { 326 if (c == 'r') { 327 clearcmdentry(0); 328 } else if (c == 'v') { 329 verbose++; 330 } 331 } 332 while ((name = *argptr) != NULL) { 333 if ((cmdp = cmdlookup(name, 0)) != NULL 334 && (cmdp->cmdtype == CMDNORMAL 335 || cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)) 336 delete_cmd_entry(); 337 find_command(name, &entry, 1); 338 if (verbose) { 339 if (entry.cmdtype != CMDUNKNOWN) { /* if no error msg */ 340 cmdp = cmdlookup(name, 0); 341 printentry(cmdp); 342 } 343 flushall(); 344 } 345 argptr++; 346 } 347 return 0; 348 } 349 350 351 STATIC void 352 printentry(cmdp) 353 struct tblentry *cmdp; 354 { 355 int index; 356 char *path; 357 char *name; 358 359 if (cmdp->cmdtype == CMDNORMAL) { 360 index = cmdp->param.index; 361 path = pathval(); 362 do { 363 name = padvance(&path, cmdp->cmdname); 364 stunalloc(name); 365 } while (--index >= 0); 366 out1str(name); 367 } else if (cmdp->cmdtype == CMDBUILTIN) { 368 out1fmt("builtin %s", cmdp->cmdname); 369 } else if (cmdp->cmdtype == CMDFUNCTION) { 370 out1fmt("function %s", cmdp->cmdname); 371 #ifdef DEBUG 372 } else { 373 error("internal error: cmdtype %d", cmdp->cmdtype); 374 #endif 375 } 376 if (cmdp->rehash) 377 out1c('*'); 378 out1c('\n'); 379 } 380 381 382 383 /* 384 * Resolve a command name. If you change this routine, you may have to 385 * change the shellexec routine as well. 386 */ 387 388 void 389 find_command(name, entry, printerr) 390 char *name; 391 struct cmdentry *entry; 392 { 393 struct tblentry *cmdp; 394 int index; 395 int prev; 396 char *path; 397 char *fullname; 398 struct stat statb; 399 int e; 400 int i; 401 402 /* If name contains a slash, don't use the hash table */ 403 if (strchr(name, '/') != NULL) { 404 entry->cmdtype = CMDNORMAL; 405 entry->u.index = 0; 406 return; 407 } 408 409 /* If name is in the table, and not invalidated by cd, we're done */ 410 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0) 411 goto success; 412 413 /* If %builtin not in path, check for builtin next */ 414 if (builtinloc < 0 && (i = find_builtin(name)) >= 0) { 415 INTOFF; 416 cmdp = cmdlookup(name, 1); 417 cmdp->cmdtype = CMDBUILTIN; 418 cmdp->param.index = i; 419 INTON; 420 goto success; 421 } 422 423 /* We have to search path. */ 424 prev = -1; /* where to start */ 425 if (cmdp) { /* doing a rehash */ 426 if (cmdp->cmdtype == CMDBUILTIN) 427 prev = builtinloc; 428 else 429 prev = cmdp->param.index; 430 } 431 432 path = pathval(); 433 e = ENOENT; 434 index = -1; 435 loop: 436 while ((fullname = padvance(&path, name)) != NULL) { 437 stunalloc(fullname); 438 index++; 439 if (pathopt) { 440 if (prefix("builtin", pathopt)) { 441 if ((i = find_builtin(name)) < 0) 442 goto loop; 443 INTOFF; 444 cmdp = cmdlookup(name, 1); 445 cmdp->cmdtype = CMDBUILTIN; 446 cmdp->param.index = i; 447 INTON; 448 goto success; 449 } else if (prefix("func", pathopt)) { 450 /* handled below */ 451 } else { 452 goto loop; /* ignore unimplemented options */ 453 } 454 } 455 /* if rehash, don't redo absolute path names */ 456 if (fullname[0] == '/' && index <= prev) { 457 if (index < prev) 458 goto loop; 459 TRACE(("searchexec \"%s\": no change\n", name)); 460 goto success; 461 } 462 while (stat(fullname, &statb) < 0) { 463 #ifdef SYSV 464 if (errno == EINTR) 465 continue; 466 #endif 467 if (errno != ENOENT && errno != ENOTDIR) 468 e = errno; 469 goto loop; 470 } 471 e = EACCES; /* if we fail, this will be the error */ 472 if ((statb.st_mode & S_IFMT) != S_IFREG) 473 goto loop; 474 if (pathopt) { /* this is a %func directory */ 475 stalloc(strlen(fullname) + 1); 476 readcmdfile(fullname); 477 if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION) 478 error("%s not defined in %s", name, fullname); 479 stunalloc(fullname); 480 goto success; 481 } 482 if (statb.st_uid == geteuid()) { 483 if ((statb.st_mode & 0100) == 0) 484 goto loop; 485 } else if (statb.st_gid == getegid()) { 486 if ((statb.st_mode & 010) == 0) 487 goto loop; 488 } else { 489 if ((statb.st_mode & 01) == 0) 490 goto loop; 491 } 492 TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname)); 493 INTOFF; 494 cmdp = cmdlookup(name, 1); 495 cmdp->cmdtype = CMDNORMAL; 496 cmdp->param.index = index; 497 INTON; 498 goto success; 499 } 500 501 /* We failed. If there was an entry for this command, delete it */ 502 if (cmdp) 503 delete_cmd_entry(); 504 if (printerr) 505 outfmt(out2, "%s: %s\n", name, errmsg(e, E_EXEC)); 506 entry->cmdtype = CMDUNKNOWN; 507 return; 508 509 success: 510 cmdp->rehash = 0; 511 entry->cmdtype = cmdp->cmdtype; 512 entry->u = cmdp->param; 513 } 514 515 516 517 /* 518 * Search the table of builtin commands. 519 */ 520 521 int 522 find_builtin(name) 523 char *name; 524 { 525 const register struct builtincmd *bp; 526 527 for (bp = builtincmd ; bp->name ; bp++) { 528 if (*bp->name == *name && equal(bp->name, name)) 529 return bp->code; 530 } 531 return -1; 532 } 533 534 535 536 /* 537 * Called when a cd is done. Marks all commands so the next time they 538 * are executed they will be rehashed. 539 */ 540 541 void 542 hashcd() { 543 struct tblentry **pp; 544 struct tblentry *cmdp; 545 546 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { 547 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 548 if (cmdp->cmdtype == CMDNORMAL 549 || cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0) 550 cmdp->rehash = 1; 551 } 552 } 553 } 554 555 556 557 /* 558 * Called before PATH is changed. The argument is the new value of PATH; 559 * pathval() still returns the old value at this point. Called with 560 * interrupts off. 561 */ 562 563 void 564 changepath(newval) 565 char *newval; 566 { 567 char *old, *new; 568 int index; 569 int firstchange; 570 int bltin; 571 int hasdot; 572 573 old = pathval(); 574 new = newval; 575 firstchange = 9999; /* assume no change */ 576 index = hasdot = 0; 577 bltin = -1; 578 if (*new == ':') 579 hasdot++; 580 for (;;) { 581 if (*old != *new) { 582 firstchange = index; 583 if (*old == '\0' && *new == ':' 584 || *old == ':' && *new == '\0') 585 firstchange++; 586 old = new; /* ignore subsequent differences */ 587 } 588 if (*new == '\0') 589 break; 590 if (*new == '%' && bltin < 0 && prefix("builtin", new + 1)) 591 bltin = index; 592 if (*new == ':') { 593 char c = *(new+1); 594 595 index++; 596 if (c == ':' || c == '\0' || (c == '.' && 597 ((c = *(new+2)) == ':' || c == '\0'))) 598 hasdot++; 599 } 600 new++, old++; 601 } 602 if (hasdot && geteuid() == 0) 603 out2str("sh: warning: running as root with dot in PATH\n"); 604 if (builtinloc < 0 && bltin >= 0) 605 builtinloc = bltin; /* zap builtins */ 606 if (builtinloc >= 0 && bltin < 0) 607 firstchange = 0; 608 clearcmdentry(firstchange); 609 builtinloc = bltin; 610 } 611 612 613 /* 614 * Clear out command entries. The argument specifies the first entry in 615 * PATH which has changed. 616 */ 617 618 STATIC void 619 clearcmdentry(firstchange) { 620 struct tblentry **tblp; 621 struct tblentry **pp; 622 struct tblentry *cmdp; 623 624 INTOFF; 625 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) { 626 pp = tblp; 627 while ((cmdp = *pp) != NULL) { 628 if (cmdp->cmdtype == CMDNORMAL && cmdp->param.index >= firstchange 629 || cmdp->cmdtype == CMDBUILTIN && builtinloc >= firstchange) { 630 *pp = cmdp->next; 631 ckfree(cmdp); 632 } else { 633 pp = &cmdp->next; 634 } 635 } 636 } 637 INTON; 638 } 639 640 641 /* 642 * Delete all functions. 643 */ 644 645 #ifdef mkinit 646 MKINIT void deletefuncs(); 647 648 SHELLPROC { 649 deletefuncs(); 650 } 651 #endif 652 653 void 654 deletefuncs() { 655 struct tblentry **tblp; 656 struct tblentry **pp; 657 struct tblentry *cmdp; 658 659 INTOFF; 660 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) { 661 pp = tblp; 662 while ((cmdp = *pp) != NULL) { 663 if (cmdp->cmdtype == CMDFUNCTION) { 664 *pp = cmdp->next; 665 freefunc(cmdp->param.func); 666 ckfree(cmdp); 667 } else { 668 pp = &cmdp->next; 669 } 670 } 671 } 672 INTON; 673 } 674 675 676 677 /* 678 * Locate a command in the command hash table. If "add" is nonzero, 679 * add the command to the table if it is not already present. The 680 * variable "lastcmdentry" is set to point to the address of the link 681 * pointing to the entry, so that delete_cmd_entry can delete the 682 * entry. 683 */ 684 685 struct tblentry **lastcmdentry; 686 687 688 STATIC struct tblentry * 689 cmdlookup(name, add) 690 char *name; 691 { 692 int hashval; 693 register char *p; 694 struct tblentry *cmdp; 695 struct tblentry **pp; 696 697 p = name; 698 hashval = *p << 4; 699 while (*p) 700 hashval += *p++; 701 hashval &= 0x7FFF; 702 pp = &cmdtable[hashval % CMDTABLESIZE]; 703 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 704 if (equal(cmdp->cmdname, name)) 705 break; 706 pp = &cmdp->next; 707 } 708 if (add && cmdp == NULL) { 709 INTOFF; 710 cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB 711 + strlen(name) + 1); 712 cmdp->next = NULL; 713 cmdp->cmdtype = CMDUNKNOWN; 714 cmdp->rehash = 0; 715 strcpy(cmdp->cmdname, name); 716 INTON; 717 } 718 lastcmdentry = pp; 719 return cmdp; 720 } 721 722 723 /* 724 * Delete the command entry returned on the last lookup. 725 */ 726 727 STATIC void 728 delete_cmd_entry() { 729 struct tblentry *cmdp; 730 731 INTOFF; 732 cmdp = *lastcmdentry; 733 *lastcmdentry = cmdp->next; 734 ckfree(cmdp); 735 INTON; 736 } 737 738 739 740 #ifdef notdef 741 void 742 getcmdentry(name, entry) 743 char *name; 744 struct cmdentry *entry; 745 { 746 struct tblentry *cmdp = cmdlookup(name, 0); 747 748 if (cmdp) { 749 entry->u = cmdp->param; 750 entry->cmdtype = cmdp->cmdtype; 751 } else { 752 entry->cmdtype = CMDUNKNOWN; 753 entry->u.index = 0; 754 } 755 } 756 #endif 757 758 759 /* 760 * Add a new command entry, replacing any existing command entry for 761 * the same name. 762 */ 763 764 void 765 addcmdentry(name, entry) 766 char *name; 767 struct cmdentry *entry; 768 { 769 struct tblentry *cmdp; 770 771 INTOFF; 772 cmdp = cmdlookup(name, 1); 773 if (cmdp->cmdtype == CMDFUNCTION) { 774 freefunc(cmdp->param.func); 775 } 776 cmdp->cmdtype = entry->cmdtype; 777 cmdp->param = entry->u; 778 INTON; 779 } 780 781 782 /* 783 * Define a shell function. 784 */ 785 786 void 787 defun(name, func) 788 char *name; 789 union node *func; 790 { 791 struct cmdentry entry; 792 793 INTOFF; 794 entry.cmdtype = CMDFUNCTION; 795 entry.u.func = copyfunc(func); 796 addcmdentry(name, &entry); 797 INTON; 798 } 799 800 801 /* 802 * Delete a function if it exists. 803 */ 804 805 void 806 unsetfunc(name) 807 char *name; 808 { 809 struct tblentry *cmdp; 810 811 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) { 812 freefunc(cmdp->param.func); 813 delete_cmd_entry(); 814 } 815 } 816