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 * %sccs.include.redist.c% 9 */ 10 11 #ifndef lint 12 static char sccsid[] = "@(#)exec.c 8.3 (Berkeley) 05/04/95"; 13 #endif /* not lint */ 14 15 #include <sys/types.h> 16 #include <sys/stat.h> 17 #include <unistd.h> 18 #include <fcntl.h> 19 #include <errno.h> 20 #include <stdlib.h> 21 22 /* 23 * When commands are first encountered, they are entered in a hash table. 24 * This ensures that a full path search will not have to be done for them 25 * on each invocation. 26 * 27 * We should investigate converting to a linear search, even though that 28 * would make the command name "hash" a misnomer. 29 */ 30 31 #include "shell.h" 32 #include "main.h" 33 #include "nodes.h" 34 #include "parser.h" 35 #include "redir.h" 36 #include "eval.h" 37 #include "exec.h" 38 #include "builtins.h" 39 #include "var.h" 40 #include "options.h" 41 #include "input.h" 42 #include "output.h" 43 #include "syntax.h" 44 #include "memalloc.h" 45 #include "error.h" 46 #include "init.h" 47 #include "mystring.h" 48 #include "show.h" 49 #include "jobs.h" 50 51 52 #define CMDTABLESIZE 31 /* should be prime */ 53 #define ARB 1 /* actual size determined at run time */ 54 55 56 57 struct tblentry { 58 struct tblentry *next; /* next entry in hash chain */ 59 union param param; /* definition of builtin function */ 60 short cmdtype; /* index identifying command */ 61 char rehash; /* if set, cd done since entry created */ 62 char cmdname[ARB]; /* name of command */ 63 }; 64 65 66 STATIC struct tblentry *cmdtable[CMDTABLESIZE]; 67 STATIC int builtinloc = -1; /* index in path of %builtin, or -1 */ 68 69 70 STATIC void tryexec __P((char *, char **, char **)); 71 STATIC void execinterp __P((char **, char **)); 72 STATIC void printentry __P((struct tblentry *, int)); 73 STATIC void clearcmdentry __P((int)); 74 STATIC struct tblentry *cmdlookup __P((char *, int)); 75 STATIC void delete_cmd_entry __P((void)); 76 77 78 79 /* 80 * Exec a program. Never returns. If you change this routine, you may 81 * have to change the find_command routine as well. 82 */ 83 84 void 85 shellexec(argv, envp, path, index) 86 char **argv, **envp; 87 char *path; 88 int index; 89 { 90 char *cmdname; 91 int e; 92 93 if (strchr(argv[0], '/') != NULL) { 94 tryexec(argv[0], argv, envp); 95 e = errno; 96 } else { 97 e = ENOENT; 98 while ((cmdname = padvance(&path, argv[0])) != NULL) { 99 if (--index < 0 && pathopt == NULL) { 100 tryexec(cmdname, argv, envp); 101 if (errno != ENOENT && errno != ENOTDIR) 102 e = errno; 103 } 104 stunalloc(cmdname); 105 } 106 } 107 error2(argv[0], errmsg(e, E_EXEC)); 108 } 109 110 111 STATIC void 112 tryexec(cmd, argv, envp) 113 char *cmd; 114 char **argv; 115 char **envp; 116 { 117 int e; 118 #ifndef BSD 119 char *p; 120 #endif 121 122 #ifdef SYSV 123 do { 124 execve(cmd, argv, envp); 125 } while (errno == EINTR); 126 #else 127 execve(cmd, argv, envp); 128 #endif 129 e = errno; 130 if (e == ENOEXEC) { 131 initshellproc(); 132 setinputfile(cmd, 0); 133 commandname = arg0 = savestr(argv[0]); 134 #ifndef BSD 135 pgetc(); pungetc(); /* fill up input buffer */ 136 p = parsenextc; 137 if (parsenleft > 2 && p[0] == '#' && p[1] == '!') { 138 argv[0] = cmd; 139 execinterp(argv, envp); 140 } 141 #endif 142 setparam(argv + 1); 143 exraise(EXSHELLPROC); 144 /*NOTREACHED*/ 145 } 146 errno = e; 147 } 148 149 150 #ifndef BSD 151 /* 152 * Execute an interpreter introduced by "#!", for systems where this 153 * feature has not been built into the kernel. If the interpreter is 154 * the shell, return (effectively ignoring the "#!"). If the execution 155 * of the interpreter fails, exit. 156 * 157 * This code peeks inside the input buffer in order to avoid actually 158 * reading any input. It would benefit from a rewrite. 159 */ 160 161 #define NEWARGS 5 162 163 STATIC void 164 execinterp(argv, envp) 165 char **argv, **envp; 166 { 167 int n; 168 char *inp; 169 char *outp; 170 char c; 171 char *p; 172 char **ap; 173 char *newargs[NEWARGS]; 174 int i; 175 char **ap2; 176 char **new; 177 178 n = parsenleft - 2; 179 inp = parsenextc + 2; 180 ap = newargs; 181 for (;;) { 182 while (--n >= 0 && (*inp == ' ' || *inp == '\t')) 183 inp++; 184 if (n < 0) 185 goto bad; 186 if ((c = *inp++) == '\n') 187 break; 188 if (ap == &newargs[NEWARGS]) 189 bad: error("Bad #! line"); 190 STARTSTACKSTR(outp); 191 do { 192 STPUTC(c, outp); 193 } while (--n >= 0 && (c = *inp++) != ' ' && c != '\t' && c != '\n'); 194 STPUTC('\0', outp); 195 n++, inp--; 196 *ap++ = grabstackstr(outp); 197 } 198 if (ap == newargs + 1) { /* if no args, maybe no exec is needed */ 199 p = newargs[0]; 200 for (;;) { 201 if (equal(p, "sh") || equal(p, "ash")) { 202 return; 203 } 204 while (*p != '/') { 205 if (*p == '\0') 206 goto break2; 207 p++; 208 } 209 p++; 210 } 211 break2:; 212 } 213 i = (char *)ap - (char *)newargs; /* size in bytes */ 214 if (i == 0) 215 error("Bad #! line"); 216 for (ap2 = argv ; *ap2++ != NULL ; ); 217 new = ckmalloc(i + ((char *)ap2 - (char *)argv)); 218 ap = newargs, ap2 = new; 219 while ((i -= sizeof (char **)) >= 0) 220 *ap2++ = *ap++; 221 ap = argv; 222 while (*ap2++ = *ap++); 223 shellexec(new, envp, pathval(), 0); 224 } 225 #endif 226 227 228 229 /* 230 * Do a path search. The variable path (passed by reference) should be 231 * set to the start of the path before the first call; padvance will update 232 * this value as it proceeds. Successive calls to padvance will return 233 * the possible path expansions in sequence. If an option (indicated by 234 * a percent sign) appears in the path entry then the global variable 235 * pathopt will be set to point to it; otherwise pathopt will be set to 236 * NULL. 237 */ 238 239 char *pathopt; 240 241 char * 242 padvance(path, name) 243 char **path; 244 char *name; 245 { 246 register char *p, *q; 247 char *start; 248 int len; 249 250 if (*path == NULL) 251 return NULL; 252 start = *path; 253 for (p = start ; *p && *p != ':' && *p != '%' ; p++); 254 len = p - start + strlen(name) + 2; /* "2" is for '/' and '\0' */ 255 while (stackblocksize() < len) 256 growstackblock(); 257 q = stackblock(); 258 if (p != start) { 259 memcpy(q, start, p - start); 260 q += p - start; 261 *q++ = '/'; 262 } 263 strcpy(q, name); 264 pathopt = NULL; 265 if (*p == '%') { 266 pathopt = ++p; 267 while (*p && *p != ':') p++; 268 } 269 if (*p == ':') 270 *path = p + 1; 271 else 272 *path = NULL; 273 return stalloc(len); 274 } 275 276 277 278 /*** Command hashing code ***/ 279 280 281 int 282 hashcmd(argc, argv) 283 int argc; 284 char **argv; 285 { 286 struct tblentry **pp; 287 struct tblentry *cmdp; 288 int c; 289 int verbose; 290 struct cmdentry entry; 291 char *name; 292 293 verbose = 0; 294 while ((c = nextopt("rv")) != '\0') { 295 if (c == 'r') { 296 clearcmdentry(0); 297 } else if (c == 'v') { 298 verbose++; 299 } 300 } 301 if (*argptr == NULL) { 302 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { 303 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 304 printentry(cmdp, verbose); 305 } 306 } 307 return 0; 308 } 309 while ((name = *argptr) != NULL) { 310 if ((cmdp = cmdlookup(name, 0)) != NULL 311 && (cmdp->cmdtype == CMDNORMAL 312 || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))) 313 delete_cmd_entry(); 314 find_command(name, &entry, 1); 315 if (verbose) { 316 if (entry.cmdtype != CMDUNKNOWN) { /* if no error msg */ 317 cmdp = cmdlookup(name, 0); 318 printentry(cmdp, verbose); 319 } 320 flushall(); 321 } 322 argptr++; 323 } 324 return 0; 325 } 326 327 328 STATIC void 329 printentry(cmdp, verbose) 330 struct tblentry *cmdp; 331 int verbose; 332 { 333 int index; 334 char *path; 335 char *name; 336 337 if (cmdp->cmdtype == CMDNORMAL) { 338 index = cmdp->param.index; 339 path = pathval(); 340 do { 341 name = padvance(&path, cmdp->cmdname); 342 stunalloc(name); 343 } while (--index >= 0); 344 out1str(name); 345 } else if (cmdp->cmdtype == CMDBUILTIN) { 346 out1fmt("builtin %s", cmdp->cmdname); 347 } else if (cmdp->cmdtype == CMDFUNCTION) { 348 out1fmt("function %s", cmdp->cmdname); 349 if (verbose) { 350 INTOFF; 351 name = commandtext(cmdp->param.func); 352 out1c(' '); 353 out1str(name); 354 ckfree(name); 355 INTON; 356 } 357 #ifdef DEBUG 358 } else { 359 error("internal error: cmdtype %d", cmdp->cmdtype); 360 #endif 361 } 362 if (cmdp->rehash) 363 out1c('*'); 364 out1c('\n'); 365 } 366 367 368 369 /* 370 * Resolve a command name. If you change this routine, you may have to 371 * change the shellexec routine as well. 372 */ 373 374 void 375 find_command(name, entry, printerr) 376 char *name; 377 struct cmdentry *entry; 378 int printerr; 379 { 380 struct tblentry *cmdp; 381 int index; 382 int prev; 383 char *path; 384 char *fullname; 385 struct stat statb; 386 int e; 387 int i; 388 389 /* If name contains a slash, don't use the hash table */ 390 if (strchr(name, '/') != NULL) { 391 entry->cmdtype = CMDNORMAL; 392 entry->u.index = 0; 393 return; 394 } 395 396 /* If name is in the table, and not invalidated by cd, we're done */ 397 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0) 398 goto success; 399 400 /* If %builtin not in path, check for builtin next */ 401 if (builtinloc < 0 && (i = find_builtin(name)) >= 0) { 402 INTOFF; 403 cmdp = cmdlookup(name, 1); 404 cmdp->cmdtype = CMDBUILTIN; 405 cmdp->param.index = i; 406 INTON; 407 goto success; 408 } 409 410 /* We have to search path. */ 411 prev = -1; /* where to start */ 412 if (cmdp) { /* doing a rehash */ 413 if (cmdp->cmdtype == CMDBUILTIN) 414 prev = builtinloc; 415 else 416 prev = cmdp->param.index; 417 } 418 419 path = pathval(); 420 e = ENOENT; 421 index = -1; 422 loop: 423 while ((fullname = padvance(&path, name)) != NULL) { 424 stunalloc(fullname); 425 index++; 426 if (pathopt) { 427 if (prefix("builtin", pathopt)) { 428 if ((i = find_builtin(name)) < 0) 429 goto loop; 430 INTOFF; 431 cmdp = cmdlookup(name, 1); 432 cmdp->cmdtype = CMDBUILTIN; 433 cmdp->param.index = i; 434 INTON; 435 goto success; 436 } else if (prefix("func", pathopt)) { 437 /* handled below */ 438 } else { 439 goto loop; /* ignore unimplemented options */ 440 } 441 } 442 /* if rehash, don't redo absolute path names */ 443 if (fullname[0] == '/' && index <= prev) { 444 if (index < prev) 445 goto loop; 446 TRACE(("searchexec \"%s\": no change\n", name)); 447 goto success; 448 } 449 while (stat(fullname, &statb) < 0) { 450 #ifdef SYSV 451 if (errno == EINTR) 452 continue; 453 #endif 454 if (errno != ENOENT && errno != ENOTDIR) 455 e = errno; 456 goto loop; 457 } 458 e = EACCES; /* if we fail, this will be the error */ 459 if (!S_ISREG(statb.st_mode)) 460 goto loop; 461 if (pathopt) { /* this is a %func directory */ 462 stalloc(strlen(fullname) + 1); 463 readcmdfile(fullname); 464 if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION) 465 error("%s not defined in %s", name, fullname); 466 stunalloc(fullname); 467 goto success; 468 } 469 #ifdef notdef 470 if (statb.st_uid == geteuid()) { 471 if ((statb.st_mode & 0100) == 0) 472 goto loop; 473 } else if (statb.st_gid == getegid()) { 474 if ((statb.st_mode & 010) == 0) 475 goto loop; 476 } else { 477 if ((statb.st_mode & 01) == 0) 478 goto loop; 479 } 480 #endif 481 TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname)); 482 INTOFF; 483 cmdp = cmdlookup(name, 1); 484 cmdp->cmdtype = CMDNORMAL; 485 cmdp->param.index = index; 486 INTON; 487 goto success; 488 } 489 490 /* We failed. If there was an entry for this command, delete it */ 491 if (cmdp) 492 delete_cmd_entry(); 493 if (printerr) 494 outfmt(out2, "%s: %s\n", name, errmsg(e, E_EXEC)); 495 entry->cmdtype = CMDUNKNOWN; 496 return; 497 498 success: 499 cmdp->rehash = 0; 500 entry->cmdtype = cmdp->cmdtype; 501 entry->u = cmdp->param; 502 } 503 504 505 506 /* 507 * Search the table of builtin commands. 508 */ 509 510 int 511 find_builtin(name) 512 char *name; 513 { 514 register const struct builtincmd *bp; 515 516 for (bp = builtincmd ; bp->name ; bp++) { 517 if (*bp->name == *name && equal(bp->name, name)) 518 return bp->code; 519 } 520 return -1; 521 } 522 523 524 525 /* 526 * Called when a cd is done. Marks all commands so the next time they 527 * are executed they will be rehashed. 528 */ 529 530 void 531 hashcd() { 532 struct tblentry **pp; 533 struct tblentry *cmdp; 534 535 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { 536 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 537 if (cmdp->cmdtype == CMDNORMAL 538 || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)) 539 cmdp->rehash = 1; 540 } 541 } 542 } 543 544 545 546 /* 547 * Called before PATH is changed. The argument is the new value of PATH; 548 * pathval() still returns the old value at this point. Called with 549 * interrupts off. 550 */ 551 552 void 553 changepath(newval) 554 char *newval; 555 { 556 char *old, *new; 557 int index; 558 int firstchange; 559 int bltin; 560 561 old = pathval(); 562 new = newval; 563 firstchange = 9999; /* assume no change */ 564 index = 0; 565 bltin = -1; 566 for (;;) { 567 if (*old != *new) { 568 firstchange = index; 569 if ((*old == '\0' && *new == ':') 570 || (*old == ':' && *new == '\0')) 571 firstchange++; 572 old = new; /* ignore subsequent differences */ 573 } 574 if (*new == '\0') 575 break; 576 if (*new == '%' && bltin < 0 && prefix("builtin", new + 1)) 577 bltin = index; 578 if (*new == ':') { 579 index++; 580 } 581 new++, old++; 582 } 583 if (builtinloc < 0 && bltin >= 0) 584 builtinloc = bltin; /* zap builtins */ 585 if (builtinloc >= 0 && bltin < 0) 586 firstchange = 0; 587 clearcmdentry(firstchange); 588 builtinloc = bltin; 589 } 590 591 592 /* 593 * Clear out command entries. The argument specifies the first entry in 594 * PATH which has changed. 595 */ 596 597 STATIC void 598 clearcmdentry(firstchange) 599 int firstchange; 600 { 601 struct tblentry **tblp; 602 struct tblentry **pp; 603 struct tblentry *cmdp; 604 605 INTOFF; 606 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) { 607 pp = tblp; 608 while ((cmdp = *pp) != NULL) { 609 if ((cmdp->cmdtype == CMDNORMAL && 610 cmdp->param.index >= firstchange) 611 || (cmdp->cmdtype == CMDBUILTIN && 612 builtinloc >= firstchange)) { 613 *pp = cmdp->next; 614 ckfree(cmdp); 615 } else { 616 pp = &cmdp->next; 617 } 618 } 619 } 620 INTON; 621 } 622 623 624 /* 625 * Delete all functions. 626 */ 627 628 #ifdef mkinit 629 MKINIT void deletefuncs(); 630 631 SHELLPROC { 632 deletefuncs(); 633 } 634 #endif 635 636 void 637 deletefuncs() { 638 struct tblentry **tblp; 639 struct tblentry **pp; 640 struct tblentry *cmdp; 641 642 INTOFF; 643 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) { 644 pp = tblp; 645 while ((cmdp = *pp) != NULL) { 646 if (cmdp->cmdtype == CMDFUNCTION) { 647 *pp = cmdp->next; 648 freefunc(cmdp->param.func); 649 ckfree(cmdp); 650 } else { 651 pp = &cmdp->next; 652 } 653 } 654 } 655 INTON; 656 } 657 658 659 660 /* 661 * Locate a command in the command hash table. If "add" is nonzero, 662 * add the command to the table if it is not already present. The 663 * variable "lastcmdentry" is set to point to the address of the link 664 * pointing to the entry, so that delete_cmd_entry can delete the 665 * entry. 666 */ 667 668 struct tblentry **lastcmdentry; 669 670 671 STATIC struct tblentry * 672 cmdlookup(name, add) 673 char *name; 674 int add; 675 { 676 int hashval; 677 register char *p; 678 struct tblentry *cmdp; 679 struct tblentry **pp; 680 681 p = name; 682 hashval = *p << 4; 683 while (*p) 684 hashval += *p++; 685 hashval &= 0x7FFF; 686 pp = &cmdtable[hashval % CMDTABLESIZE]; 687 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 688 if (equal(cmdp->cmdname, name)) 689 break; 690 pp = &cmdp->next; 691 } 692 if (add && cmdp == NULL) { 693 INTOFF; 694 cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB 695 + strlen(name) + 1); 696 cmdp->next = NULL; 697 cmdp->cmdtype = CMDUNKNOWN; 698 cmdp->rehash = 0; 699 strcpy(cmdp->cmdname, name); 700 INTON; 701 } 702 lastcmdentry = pp; 703 return cmdp; 704 } 705 706 /* 707 * Delete the command entry returned on the last lookup. 708 */ 709 710 STATIC void 711 delete_cmd_entry() { 712 struct tblentry *cmdp; 713 714 INTOFF; 715 cmdp = *lastcmdentry; 716 *lastcmdentry = cmdp->next; 717 ckfree(cmdp); 718 INTON; 719 } 720 721 722 723 #ifdef notdef 724 void 725 getcmdentry(name, entry) 726 char *name; 727 struct cmdentry *entry; 728 { 729 struct tblentry *cmdp = cmdlookup(name, 0); 730 731 if (cmdp) { 732 entry->u = cmdp->param; 733 entry->cmdtype = cmdp->cmdtype; 734 } else { 735 entry->cmdtype = CMDUNKNOWN; 736 entry->u.index = 0; 737 } 738 } 739 #endif 740 741 742 /* 743 * Add a new command entry, replacing any existing command entry for 744 * the same name. 745 */ 746 747 void 748 addcmdentry(name, entry) 749 char *name; 750 struct cmdentry *entry; 751 { 752 struct tblentry *cmdp; 753 754 INTOFF; 755 cmdp = cmdlookup(name, 1); 756 if (cmdp->cmdtype == CMDFUNCTION) { 757 freefunc(cmdp->param.func); 758 } 759 cmdp->cmdtype = entry->cmdtype; 760 cmdp->param = entry->u; 761 INTON; 762 } 763 764 765 /* 766 * Define a shell function. 767 */ 768 769 void 770 defun(name, func) 771 char *name; 772 union node *func; 773 { 774 struct cmdentry entry; 775 776 INTOFF; 777 entry.cmdtype = CMDFUNCTION; 778 entry.u.func = copyfunc(func); 779 addcmdentry(name, &entry); 780 INTON; 781 } 782 783 784 /* 785 * Delete a function if it exists. 786 */ 787 788 int 789 unsetfunc(name) 790 char *name; 791 { 792 struct tblentry *cmdp; 793 794 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) { 795 freefunc(cmdp->param.func); 796 delete_cmd_entry(); 797 return (0); 798 } 799 return (1); 800 } 801