1 /* $NetBSD: exec.c,v 1.18 1996/06/25 16:40:38 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Kenneth Almquist. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #ifndef lint 40 #if 0 41 static char sccsid[] = "@(#)exec.c 8.4 (Berkeley) 6/8/95"; 42 #else 43 static char rcsid[] = "$NetBSD: exec.c,v 1.18 1996/06/25 16:40:38 christos Exp $"; 44 #endif 45 #endif /* not lint */ 46 47 #include <sys/types.h> 48 #include <sys/stat.h> 49 #include <unistd.h> 50 #include <fcntl.h> 51 #include <errno.h> 52 #include <stdlib.h> 53 54 /* 55 * When commands are first encountered, they are entered in a hash table. 56 * This ensures that a full path search will not have to be done for them 57 * on each invocation. 58 * 59 * We should investigate converting to a linear search, even though that 60 * would make the command name "hash" a misnomer. 61 */ 62 63 #include "shell.h" 64 #include "main.h" 65 #include "nodes.h" 66 #include "parser.h" 67 #include "redir.h" 68 #include "eval.h" 69 #include "exec.h" 70 #include "builtins.h" 71 #include "var.h" 72 #include "options.h" 73 #include "input.h" 74 #include "output.h" 75 #include "syntax.h" 76 #include "memalloc.h" 77 #include "error.h" 78 #include "init.h" 79 #include "mystring.h" 80 #include "show.h" 81 #include "jobs.h" 82 83 84 #define CMDTABLESIZE 31 /* should be prime */ 85 #define ARB 1 /* actual size determined at run time */ 86 87 88 89 struct tblentry { 90 struct tblentry *next; /* next entry in hash chain */ 91 union param param; /* definition of builtin function */ 92 short cmdtype; /* index identifying command */ 93 char rehash; /* if set, cd done since entry created */ 94 char cmdname[ARB]; /* name of command */ 95 }; 96 97 98 STATIC struct tblentry *cmdtable[CMDTABLESIZE]; 99 STATIC int builtinloc = -1; /* index in path of %builtin, or -1 */ 100 101 102 STATIC void tryexec __P((char *, char **, char **)); 103 STATIC void execinterp __P((char **, char **)); 104 STATIC void printentry __P((struct tblentry *, int)); 105 STATIC void clearcmdentry __P((int)); 106 STATIC struct tblentry *cmdlookup __P((char *, int)); 107 STATIC void delete_cmd_entry __P((void)); 108 109 110 111 /* 112 * Exec a program. Never returns. If you change this routine, you may 113 * have to change the find_command routine as well. 114 */ 115 116 void 117 shellexec(argv, envp, path, index) 118 char **argv, **envp; 119 char *path; 120 int index; 121 { 122 char *cmdname; 123 int e; 124 125 if (strchr(argv[0], '/') != NULL) { 126 tryexec(argv[0], argv, envp); 127 e = errno; 128 } else { 129 e = ENOENT; 130 while ((cmdname = padvance(&path, argv[0])) != NULL) { 131 if (--index < 0 && pathopt == NULL) { 132 tryexec(cmdname, argv, envp); 133 if (errno != ENOENT && errno != ENOTDIR) 134 e = errno; 135 } 136 stunalloc(cmdname); 137 } 138 } 139 error2(argv[0], errmsg(e, E_EXEC)); 140 } 141 142 143 STATIC void 144 tryexec(cmd, argv, envp) 145 char *cmd; 146 char **argv; 147 char **envp; 148 { 149 int e; 150 #ifndef BSD 151 char *p; 152 #endif 153 154 #ifdef SYSV 155 do { 156 execve(cmd, argv, envp); 157 } while (errno == EINTR); 158 #else 159 execve(cmd, argv, envp); 160 #endif 161 e = errno; 162 if (e == ENOEXEC) { 163 initshellproc(); 164 setinputfile(cmd, 0); 165 commandname = arg0 = savestr(argv[0]); 166 #ifndef BSD 167 pgetc(); pungetc(); /* fill up input buffer */ 168 p = parsenextc; 169 if (parsenleft > 2 && p[0] == '#' && p[1] == '!') { 170 argv[0] = cmd; 171 execinterp(argv, envp); 172 } 173 #endif 174 setparam(argv + 1); 175 exraise(EXSHELLPROC); 176 /*NOTREACHED*/ 177 } 178 errno = e; 179 } 180 181 182 #ifndef BSD 183 /* 184 * Execute an interpreter introduced by "#!", for systems where this 185 * feature has not been built into the kernel. If the interpreter is 186 * the shell, return (effectively ignoring the "#!"). If the execution 187 * of the interpreter fails, exit. 188 * 189 * This code peeks inside the input buffer in order to avoid actually 190 * reading any input. It would benefit from a rewrite. 191 */ 192 193 #define NEWARGS 5 194 195 STATIC void 196 execinterp(argv, envp) 197 char **argv, **envp; 198 { 199 int n; 200 char *inp; 201 char *outp; 202 char c; 203 char *p; 204 char **ap; 205 char *newargs[NEWARGS]; 206 int i; 207 char **ap2; 208 char **new; 209 210 n = parsenleft - 2; 211 inp = parsenextc + 2; 212 ap = newargs; 213 for (;;) { 214 while (--n >= 0 && (*inp == ' ' || *inp == '\t')) 215 inp++; 216 if (n < 0) 217 goto bad; 218 if ((c = *inp++) == '\n') 219 break; 220 if (ap == &newargs[NEWARGS]) 221 bad: error("Bad #! line"); 222 STARTSTACKSTR(outp); 223 do { 224 STPUTC(c, outp); 225 } while (--n >= 0 && (c = *inp++) != ' ' && c != '\t' && c != '\n'); 226 STPUTC('\0', outp); 227 n++, inp--; 228 *ap++ = grabstackstr(outp); 229 } 230 if (ap == newargs + 1) { /* if no args, maybe no exec is needed */ 231 p = newargs[0]; 232 for (;;) { 233 if (equal(p, "sh") || equal(p, "ash")) { 234 return; 235 } 236 while (*p != '/') { 237 if (*p == '\0') 238 goto break2; 239 p++; 240 } 241 p++; 242 } 243 break2:; 244 } 245 i = (char *)ap - (char *)newargs; /* size in bytes */ 246 if (i == 0) 247 error("Bad #! line"); 248 for (ap2 = argv ; *ap2++ != NULL ; ); 249 new = ckmalloc(i + ((char *)ap2 - (char *)argv)); 250 ap = newargs, ap2 = new; 251 while ((i -= sizeof (char **)) >= 0) 252 *ap2++ = *ap++; 253 ap = argv; 254 while (*ap2++ = *ap++); 255 shellexec(new, envp, pathval(), 0); 256 } 257 #endif 258 259 260 261 /* 262 * Do a path search. The variable path (passed by reference) should be 263 * set to the start of the path before the first call; padvance will update 264 * this value as it proceeds. Successive calls to padvance will return 265 * the possible path expansions in sequence. If an option (indicated by 266 * a percent sign) appears in the path entry then the global variable 267 * pathopt will be set to point to it; otherwise pathopt will be set to 268 * NULL. 269 */ 270 271 char *pathopt; 272 273 char * 274 padvance(path, name) 275 char **path; 276 char *name; 277 { 278 register char *p, *q; 279 char *start; 280 int len; 281 282 if (*path == NULL) 283 return NULL; 284 start = *path; 285 for (p = start ; *p && *p != ':' && *p != '%' ; p++); 286 len = p - start + strlen(name) + 2; /* "2" is for '/' and '\0' */ 287 while (stackblocksize() < len) 288 growstackblock(); 289 q = stackblock(); 290 if (p != start) { 291 memcpy(q, start, p - start); 292 q += p - start; 293 *q++ = '/'; 294 } 295 strcpy(q, name); 296 pathopt = NULL; 297 if (*p == '%') { 298 pathopt = ++p; 299 while (*p && *p != ':') p++; 300 } 301 if (*p == ':') 302 *path = p + 1; 303 else 304 *path = NULL; 305 return stalloc(len); 306 } 307 308 309 310 /*** Command hashing code ***/ 311 312 313 int 314 hashcmd(argc, argv) 315 int argc; 316 char **argv; 317 { 318 struct tblentry **pp; 319 struct tblentry *cmdp; 320 int c; 321 int verbose; 322 struct cmdentry entry; 323 char *name; 324 325 verbose = 0; 326 while ((c = nextopt("rv")) != '\0') { 327 if (c == 'r') { 328 clearcmdentry(0); 329 } else if (c == 'v') { 330 verbose++; 331 } 332 } 333 if (*argptr == NULL) { 334 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { 335 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 336 printentry(cmdp, verbose); 337 } 338 } 339 return 0; 340 } 341 while ((name = *argptr) != NULL) { 342 if ((cmdp = cmdlookup(name, 0)) != NULL 343 && (cmdp->cmdtype == CMDNORMAL 344 || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))) 345 delete_cmd_entry(); 346 find_command(name, &entry, 1, pathval()); 347 if (verbose) { 348 if (entry.cmdtype != CMDUNKNOWN) { /* if no error msg */ 349 cmdp = cmdlookup(name, 0); 350 printentry(cmdp, verbose); 351 } 352 flushall(); 353 } 354 argptr++; 355 } 356 return 0; 357 } 358 359 360 STATIC void 361 printentry(cmdp, verbose) 362 struct tblentry *cmdp; 363 int verbose; 364 { 365 int index; 366 char *path; 367 char *name; 368 369 if (cmdp->cmdtype == CMDNORMAL) { 370 index = cmdp->param.index; 371 path = pathval(); 372 do { 373 name = padvance(&path, cmdp->cmdname); 374 stunalloc(name); 375 } while (--index >= 0); 376 out1str(name); 377 } else if (cmdp->cmdtype == CMDBUILTIN) { 378 out1fmt("builtin %s", cmdp->cmdname); 379 } else if (cmdp->cmdtype == CMDFUNCTION) { 380 out1fmt("function %s", cmdp->cmdname); 381 if (verbose) { 382 INTOFF; 383 name = commandtext(cmdp->param.func); 384 out1c(' '); 385 out1str(name); 386 ckfree(name); 387 INTON; 388 } 389 #ifdef DEBUG 390 } else { 391 error("internal error: cmdtype %d", cmdp->cmdtype); 392 #endif 393 } 394 if (cmdp->rehash) 395 out1c('*'); 396 out1c('\n'); 397 } 398 399 400 401 /* 402 * Resolve a command name. If you change this routine, you may have to 403 * change the shellexec routine as well. 404 */ 405 406 void 407 find_command(name, entry, printerr, path) 408 char *name; 409 struct cmdentry *entry; 410 int printerr; 411 char *path; 412 { 413 struct tblentry *cmdp; 414 int index; 415 int prev; 416 char *fullname; 417 struct stat statb; 418 int e; 419 int i; 420 421 /* If name contains a slash, don't use the hash table */ 422 if (strchr(name, '/') != NULL) { 423 entry->cmdtype = CMDNORMAL; 424 entry->u.index = 0; 425 return; 426 } 427 428 /* If name is in the table, and not invalidated by cd, we're done */ 429 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0) 430 goto success; 431 432 /* If %builtin not in path, check for builtin next */ 433 if (builtinloc < 0 && (i = find_builtin(name)) >= 0) { 434 INTOFF; 435 cmdp = cmdlookup(name, 1); 436 cmdp->cmdtype = CMDBUILTIN; 437 cmdp->param.index = i; 438 INTON; 439 goto success; 440 } 441 442 /* We have to search path. */ 443 prev = -1; /* where to start */ 444 if (cmdp) { /* doing a rehash */ 445 if (cmdp->cmdtype == CMDBUILTIN) 446 prev = builtinloc; 447 else 448 prev = cmdp->param.index; 449 } 450 451 e = ENOENT; 452 index = -1; 453 loop: 454 while ((fullname = padvance(&path, name)) != NULL) { 455 stunalloc(fullname); 456 index++; 457 if (pathopt) { 458 if (prefix("builtin", pathopt)) { 459 if ((i = find_builtin(name)) < 0) 460 goto loop; 461 INTOFF; 462 cmdp = cmdlookup(name, 1); 463 cmdp->cmdtype = CMDBUILTIN; 464 cmdp->param.index = i; 465 INTON; 466 goto success; 467 } else if (prefix("func", pathopt)) { 468 /* handled below */ 469 } else { 470 goto loop; /* ignore unimplemented options */ 471 } 472 } 473 /* if rehash, don't redo absolute path names */ 474 if (fullname[0] == '/' && index <= prev) { 475 if (index < prev) 476 goto loop; 477 TRACE(("searchexec \"%s\": no change\n", name)); 478 goto success; 479 } 480 while (stat(fullname, &statb) < 0) { 481 #ifdef SYSV 482 if (errno == EINTR) 483 continue; 484 #endif 485 if (errno != ENOENT && errno != ENOTDIR) 486 e = errno; 487 goto loop; 488 } 489 e = EACCES; /* if we fail, this will be the error */ 490 if (!S_ISREG(statb.st_mode)) 491 goto loop; 492 if (pathopt) { /* this is a %func directory */ 493 stalloc(strlen(fullname) + 1); 494 readcmdfile(fullname); 495 if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION) 496 error("%s not defined in %s", name, fullname); 497 stunalloc(fullname); 498 goto success; 499 } 500 #ifdef notdef 501 if (statb.st_uid == geteuid()) { 502 if ((statb.st_mode & 0100) == 0) 503 goto loop; 504 } else if (statb.st_gid == getegid()) { 505 if ((statb.st_mode & 010) == 0) 506 goto loop; 507 } else { 508 if ((statb.st_mode & 01) == 0) 509 goto loop; 510 } 511 #endif 512 TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname)); 513 INTOFF; 514 cmdp = cmdlookup(name, 1); 515 cmdp->cmdtype = CMDNORMAL; 516 cmdp->param.index = index; 517 INTON; 518 goto success; 519 } 520 521 /* We failed. If there was an entry for this command, delete it */ 522 if (cmdp) 523 delete_cmd_entry(); 524 if (printerr) 525 outfmt(out2, "%s: %s\n", name, errmsg(e, E_EXEC)); 526 entry->cmdtype = CMDUNKNOWN; 527 return; 528 529 success: 530 cmdp->rehash = 0; 531 entry->cmdtype = cmdp->cmdtype; 532 entry->u = cmdp->param; 533 } 534 535 536 537 /* 538 * Search the table of builtin commands. 539 */ 540 541 int 542 find_builtin(name) 543 char *name; 544 { 545 register const struct builtincmd *bp; 546 547 for (bp = builtincmd ; bp->name ; bp++) { 548 if (*bp->name == *name && equal(bp->name, name)) 549 return bp->code; 550 } 551 return -1; 552 } 553 554 555 556 /* 557 * Called when a cd is done. Marks all commands so the next time they 558 * are executed they will be rehashed. 559 */ 560 561 void 562 hashcd() { 563 struct tblentry **pp; 564 struct tblentry *cmdp; 565 566 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { 567 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 568 if (cmdp->cmdtype == CMDNORMAL 569 || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)) 570 cmdp->rehash = 1; 571 } 572 } 573 } 574 575 576 577 /* 578 * Called before PATH is changed. The argument is the new value of PATH; 579 * pathval() still returns the old value at this point. Called with 580 * interrupts off. 581 */ 582 583 void 584 changepath(newval) 585 const char *newval; 586 { 587 const char *old, *new; 588 int index; 589 int firstchange; 590 int bltin; 591 592 old = pathval(); 593 new = newval; 594 firstchange = 9999; /* assume no change */ 595 index = 0; 596 bltin = -1; 597 for (;;) { 598 if (*old != *new) { 599 firstchange = index; 600 if ((*old == '\0' && *new == ':') 601 || (*old == ':' && *new == '\0')) 602 firstchange++; 603 old = new; /* ignore subsequent differences */ 604 } 605 if (*new == '\0') 606 break; 607 if (*new == '%' && bltin < 0 && prefix("builtin", new + 1)) 608 bltin = index; 609 if (*new == ':') { 610 index++; 611 } 612 new++, old++; 613 } 614 if (builtinloc < 0 && bltin >= 0) 615 builtinloc = bltin; /* zap builtins */ 616 if (builtinloc >= 0 && bltin < 0) 617 firstchange = 0; 618 clearcmdentry(firstchange); 619 builtinloc = bltin; 620 } 621 622 623 /* 624 * Clear out command entries. The argument specifies the first entry in 625 * PATH which has changed. 626 */ 627 628 STATIC void 629 clearcmdentry(firstchange) 630 int firstchange; 631 { 632 struct tblentry **tblp; 633 struct tblentry **pp; 634 struct tblentry *cmdp; 635 636 INTOFF; 637 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) { 638 pp = tblp; 639 while ((cmdp = *pp) != NULL) { 640 if ((cmdp->cmdtype == CMDNORMAL && 641 cmdp->param.index >= firstchange) 642 || (cmdp->cmdtype == CMDBUILTIN && 643 builtinloc >= firstchange)) { 644 *pp = cmdp->next; 645 ckfree(cmdp); 646 } else { 647 pp = &cmdp->next; 648 } 649 } 650 } 651 INTON; 652 } 653 654 655 /* 656 * Delete all functions. 657 */ 658 659 #ifdef mkinit 660 MKINIT void deletefuncs(); 661 662 SHELLPROC { 663 deletefuncs(); 664 } 665 #endif 666 667 void 668 deletefuncs() { 669 struct tblentry **tblp; 670 struct tblentry **pp; 671 struct tblentry *cmdp; 672 673 INTOFF; 674 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) { 675 pp = tblp; 676 while ((cmdp = *pp) != NULL) { 677 if (cmdp->cmdtype == CMDFUNCTION) { 678 *pp = cmdp->next; 679 freefunc(cmdp->param.func); 680 ckfree(cmdp); 681 } else { 682 pp = &cmdp->next; 683 } 684 } 685 } 686 INTON; 687 } 688 689 690 691 /* 692 * Locate a command in the command hash table. If "add" is nonzero, 693 * add the command to the table if it is not already present. The 694 * variable "lastcmdentry" is set to point to the address of the link 695 * pointing to the entry, so that delete_cmd_entry can delete the 696 * entry. 697 */ 698 699 struct tblentry **lastcmdentry; 700 701 702 STATIC struct tblentry * 703 cmdlookup(name, add) 704 char *name; 705 int add; 706 { 707 int hashval; 708 register char *p; 709 struct tblentry *cmdp; 710 struct tblentry **pp; 711 712 p = name; 713 hashval = *p << 4; 714 while (*p) 715 hashval += *p++; 716 hashval &= 0x7FFF; 717 pp = &cmdtable[hashval % CMDTABLESIZE]; 718 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 719 if (equal(cmdp->cmdname, name)) 720 break; 721 pp = &cmdp->next; 722 } 723 if (add && cmdp == NULL) { 724 INTOFF; 725 cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB 726 + strlen(name) + 1); 727 cmdp->next = NULL; 728 cmdp->cmdtype = CMDUNKNOWN; 729 cmdp->rehash = 0; 730 strcpy(cmdp->cmdname, name); 731 INTON; 732 } 733 lastcmdentry = pp; 734 return cmdp; 735 } 736 737 /* 738 * Delete the command entry returned on the last lookup. 739 */ 740 741 STATIC void 742 delete_cmd_entry() { 743 struct tblentry *cmdp; 744 745 INTOFF; 746 cmdp = *lastcmdentry; 747 *lastcmdentry = cmdp->next; 748 ckfree(cmdp); 749 INTON; 750 } 751 752 753 754 #ifdef notdef 755 void 756 getcmdentry(name, entry) 757 char *name; 758 struct cmdentry *entry; 759 { 760 struct tblentry *cmdp = cmdlookup(name, 0); 761 762 if (cmdp) { 763 entry->u = cmdp->param; 764 entry->cmdtype = cmdp->cmdtype; 765 } else { 766 entry->cmdtype = CMDUNKNOWN; 767 entry->u.index = 0; 768 } 769 } 770 #endif 771 772 773 /* 774 * Add a new command entry, replacing any existing command entry for 775 * the same name. 776 */ 777 778 void 779 addcmdentry(name, entry) 780 char *name; 781 struct cmdentry *entry; 782 { 783 struct tblentry *cmdp; 784 785 INTOFF; 786 cmdp = cmdlookup(name, 1); 787 if (cmdp->cmdtype == CMDFUNCTION) { 788 freefunc(cmdp->param.func); 789 } 790 cmdp->cmdtype = entry->cmdtype; 791 cmdp->param = entry->u; 792 INTON; 793 } 794 795 796 /* 797 * Define a shell function. 798 */ 799 800 void 801 defun(name, func) 802 char *name; 803 union node *func; 804 { 805 struct cmdentry entry; 806 807 INTOFF; 808 entry.cmdtype = CMDFUNCTION; 809 entry.u.func = copyfunc(func); 810 addcmdentry(name, &entry); 811 INTON; 812 } 813 814 815 /* 816 * Delete a function if it exists. 817 */ 818 819 int 820 unsetfunc(name) 821 char *name; 822 { 823 struct tblentry *cmdp; 824 825 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) { 826 freefunc(cmdp->param.func); 827 delete_cmd_entry(); 828 return (0); 829 } 830 return (1); 831 } 832