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 8.4 (Berkeley) 06/08/95"; 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, pathval()); 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, path) 376 char *name; 377 struct cmdentry *entry; 378 int printerr; 379 char *path; 380 { 381 struct tblentry *cmdp; 382 int index; 383 int prev; 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 e = ENOENT; 420 index = -1; 421 loop: 422 while ((fullname = padvance(&path, name)) != NULL) { 423 stunalloc(fullname); 424 index++; 425 if (pathopt) { 426 if (prefix("builtin", pathopt)) { 427 if ((i = find_builtin(name)) < 0) 428 goto loop; 429 INTOFF; 430 cmdp = cmdlookup(name, 1); 431 cmdp->cmdtype = CMDBUILTIN; 432 cmdp->param.index = i; 433 INTON; 434 goto success; 435 } else if (prefix("func", pathopt)) { 436 /* handled below */ 437 } else { 438 goto loop; /* ignore unimplemented options */ 439 } 440 } 441 /* if rehash, don't redo absolute path names */ 442 if (fullname[0] == '/' && index <= prev) { 443 if (index < prev) 444 goto loop; 445 TRACE(("searchexec \"%s\": no change\n", name)); 446 goto success; 447 } 448 while (stat(fullname, &statb) < 0) { 449 #ifdef SYSV 450 if (errno == EINTR) 451 continue; 452 #endif 453 if (errno != ENOENT && errno != ENOTDIR) 454 e = errno; 455 goto loop; 456 } 457 e = EACCES; /* if we fail, this will be the error */ 458 if (!S_ISREG(statb.st_mode)) 459 goto loop; 460 if (pathopt) { /* this is a %func directory */ 461 stalloc(strlen(fullname) + 1); 462 readcmdfile(fullname); 463 if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION) 464 error("%s not defined in %s", name, fullname); 465 stunalloc(fullname); 466 goto success; 467 } 468 #ifdef notdef 469 if (statb.st_uid == geteuid()) { 470 if ((statb.st_mode & 0100) == 0) 471 goto loop; 472 } else if (statb.st_gid == getegid()) { 473 if ((statb.st_mode & 010) == 0) 474 goto loop; 475 } else { 476 if ((statb.st_mode & 01) == 0) 477 goto loop; 478 } 479 #endif 480 TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname)); 481 INTOFF; 482 cmdp = cmdlookup(name, 1); 483 cmdp->cmdtype = CMDNORMAL; 484 cmdp->param.index = index; 485 INTON; 486 goto success; 487 } 488 489 /* We failed. If there was an entry for this command, delete it */ 490 if (cmdp) 491 delete_cmd_entry(); 492 if (printerr) 493 outfmt(out2, "%s: %s\n", name, errmsg(e, E_EXEC)); 494 entry->cmdtype = CMDUNKNOWN; 495 return; 496 497 success: 498 cmdp->rehash = 0; 499 entry->cmdtype = cmdp->cmdtype; 500 entry->u = cmdp->param; 501 } 502 503 504 505 /* 506 * Search the table of builtin commands. 507 */ 508 509 int 510 find_builtin(name) 511 char *name; 512 { 513 register const struct builtincmd *bp; 514 515 for (bp = builtincmd ; bp->name ; bp++) { 516 if (*bp->name == *name && equal(bp->name, name)) 517 return bp->code; 518 } 519 return -1; 520 } 521 522 523 524 /* 525 * Called when a cd is done. Marks all commands so the next time they 526 * are executed they will be rehashed. 527 */ 528 529 void 530 hashcd() { 531 struct tblentry **pp; 532 struct tblentry *cmdp; 533 534 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { 535 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 536 if (cmdp->cmdtype == CMDNORMAL 537 || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)) 538 cmdp->rehash = 1; 539 } 540 } 541 } 542 543 544 545 /* 546 * Called before PATH is changed. The argument is the new value of PATH; 547 * pathval() still returns the old value at this point. Called with 548 * interrupts off. 549 */ 550 551 void 552 changepath(newval) 553 char *newval; 554 { 555 char *old, *new; 556 int index; 557 int firstchange; 558 int bltin; 559 560 old = pathval(); 561 new = newval; 562 firstchange = 9999; /* assume no change */ 563 index = 0; 564 bltin = -1; 565 for (;;) { 566 if (*old != *new) { 567 firstchange = index; 568 if ((*old == '\0' && *new == ':') 569 || (*old == ':' && *new == '\0')) 570 firstchange++; 571 old = new; /* ignore subsequent differences */ 572 } 573 if (*new == '\0') 574 break; 575 if (*new == '%' && bltin < 0 && prefix("builtin", new + 1)) 576 bltin = index; 577 if (*new == ':') { 578 index++; 579 } 580 new++, old++; 581 } 582 if (builtinloc < 0 && bltin >= 0) 583 builtinloc = bltin; /* zap builtins */ 584 if (builtinloc >= 0 && bltin < 0) 585 firstchange = 0; 586 clearcmdentry(firstchange); 587 builtinloc = bltin; 588 } 589 590 591 /* 592 * Clear out command entries. The argument specifies the first entry in 593 * PATH which has changed. 594 */ 595 596 STATIC void 597 clearcmdentry(firstchange) 598 int firstchange; 599 { 600 struct tblentry **tblp; 601 struct tblentry **pp; 602 struct tblentry *cmdp; 603 604 INTOFF; 605 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) { 606 pp = tblp; 607 while ((cmdp = *pp) != NULL) { 608 if ((cmdp->cmdtype == CMDNORMAL && 609 cmdp->param.index >= firstchange) 610 || (cmdp->cmdtype == CMDBUILTIN && 611 builtinloc >= firstchange)) { 612 *pp = cmdp->next; 613 ckfree(cmdp); 614 } else { 615 pp = &cmdp->next; 616 } 617 } 618 } 619 INTON; 620 } 621 622 623 /* 624 * Delete all functions. 625 */ 626 627 #ifdef mkinit 628 MKINIT void deletefuncs(); 629 630 SHELLPROC { 631 deletefuncs(); 632 } 633 #endif 634 635 void 636 deletefuncs() { 637 struct tblentry **tblp; 638 struct tblentry **pp; 639 struct tblentry *cmdp; 640 641 INTOFF; 642 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) { 643 pp = tblp; 644 while ((cmdp = *pp) != NULL) { 645 if (cmdp->cmdtype == CMDFUNCTION) { 646 *pp = cmdp->next; 647 freefunc(cmdp->param.func); 648 ckfree(cmdp); 649 } else { 650 pp = &cmdp->next; 651 } 652 } 653 } 654 INTON; 655 } 656 657 658 659 /* 660 * Locate a command in the command hash table. If "add" is nonzero, 661 * add the command to the table if it is not already present. The 662 * variable "lastcmdentry" is set to point to the address of the link 663 * pointing to the entry, so that delete_cmd_entry can delete the 664 * entry. 665 */ 666 667 struct tblentry **lastcmdentry; 668 669 670 STATIC struct tblentry * 671 cmdlookup(name, add) 672 char *name; 673 int add; 674 { 675 int hashval; 676 register char *p; 677 struct tblentry *cmdp; 678 struct tblentry **pp; 679 680 p = name; 681 hashval = *p << 4; 682 while (*p) 683 hashval += *p++; 684 hashval &= 0x7FFF; 685 pp = &cmdtable[hashval % CMDTABLESIZE]; 686 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { 687 if (equal(cmdp->cmdname, name)) 688 break; 689 pp = &cmdp->next; 690 } 691 if (add && cmdp == NULL) { 692 INTOFF; 693 cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB 694 + strlen(name) + 1); 695 cmdp->next = NULL; 696 cmdp->cmdtype = CMDUNKNOWN; 697 cmdp->rehash = 0; 698 strcpy(cmdp->cmdname, name); 699 INTON; 700 } 701 lastcmdentry = pp; 702 return cmdp; 703 } 704 705 /* 706 * Delete the command entry returned on the last lookup. 707 */ 708 709 STATIC void 710 delete_cmd_entry() { 711 struct tblentry *cmdp; 712 713 INTOFF; 714 cmdp = *lastcmdentry; 715 *lastcmdentry = cmdp->next; 716 ckfree(cmdp); 717 INTON; 718 } 719 720 721 722 #ifdef notdef 723 void 724 getcmdentry(name, entry) 725 char *name; 726 struct cmdentry *entry; 727 { 728 struct tblentry *cmdp = cmdlookup(name, 0); 729 730 if (cmdp) { 731 entry->u = cmdp->param; 732 entry->cmdtype = cmdp->cmdtype; 733 } else { 734 entry->cmdtype = CMDUNKNOWN; 735 entry->u.index = 0; 736 } 737 } 738 #endif 739 740 741 /* 742 * Add a new command entry, replacing any existing command entry for 743 * the same name. 744 */ 745 746 void 747 addcmdentry(name, entry) 748 char *name; 749 struct cmdentry *entry; 750 { 751 struct tblentry *cmdp; 752 753 INTOFF; 754 cmdp = cmdlookup(name, 1); 755 if (cmdp->cmdtype == CMDFUNCTION) { 756 freefunc(cmdp->param.func); 757 } 758 cmdp->cmdtype = entry->cmdtype; 759 cmdp->param = entry->u; 760 INTON; 761 } 762 763 764 /* 765 * Define a shell function. 766 */ 767 768 void 769 defun(name, func) 770 char *name; 771 union node *func; 772 { 773 struct cmdentry entry; 774 775 INTOFF; 776 entry.cmdtype = CMDFUNCTION; 777 entry.u.func = copyfunc(func); 778 addcmdentry(name, &entry); 779 INTON; 780 } 781 782 783 /* 784 * Delete a function if it exists. 785 */ 786 787 int 788 unsetfunc(name) 789 char *name; 790 { 791 struct tblentry *cmdp; 792 793 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) { 794 freefunc(cmdp->param.func); 795 delete_cmd_entry(); 796 return (0); 797 } 798 return (1); 799 } 800