1 /*- 2 * Copyright (c) 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 37 #ifndef lint 38 static char sccsid[] = "@(#)eval.c 8.1 (Berkeley) 5/31/93"; 39 #endif /* not lint */ 40 41 /* 42 * Evaluate a command. 43 */ 44 45 #include "shell.h" 46 #include "nodes.h" 47 #include "syntax.h" 48 #include "expand.h" 49 #include "parser.h" 50 #include "jobs.h" 51 #include "eval.h" 52 #include "builtins.h" 53 #include "options.h" 54 #include "exec.h" 55 #include "redir.h" 56 #include "input.h" 57 #include "output.h" 58 #include "trap.h" 59 #include "var.h" 60 #include "memalloc.h" 61 #include "error.h" 62 #include "mystring.h" 63 #include "myhistedit.h" 64 #include <signal.h> 65 66 67 /* flags in argument to evaltree */ 68 #define EV_EXIT 01 /* exit after evaluating tree */ 69 #define EV_TESTED 02 /* exit status is checked; ignore -e flag */ 70 #define EV_BACKCMD 04 /* command executing within back quotes */ 71 72 73 /* reasons for skipping commands (see comment on breakcmd routine) */ 74 #define SKIPBREAK 1 75 #define SKIPCONT 2 76 #define SKIPFUNC 3 77 78 MKINIT int evalskip; /* set if we are skipping commands */ 79 STATIC int skipcount; /* number of levels to skip */ 80 MKINIT int loopnest; /* current loop nesting level */ 81 int funcnest; /* depth of function calls */ 82 83 84 char *commandname; 85 struct strlist *cmdenviron; 86 int exitstatus; /* exit status of last command */ 87 88 89 #ifdef __STDC__ 90 STATIC void evalloop(union node *); 91 STATIC void evalfor(union node *); 92 STATIC void evalcase(union node *, int); 93 STATIC void evalsubshell(union node *, int); 94 STATIC void expredir(union node *); 95 STATIC void evalpipe(union node *); 96 STATIC void evalcommand(union node *, int, struct backcmd *); 97 STATIC void prehash(union node *); 98 #else 99 STATIC void evalloop(); 100 STATIC void evalfor(); 101 STATIC void evalcase(); 102 STATIC void evalsubshell(); 103 STATIC void expredir(); 104 STATIC void evalpipe(); 105 STATIC void evalcommand(); 106 STATIC void prehash(); 107 #endif 108 109 110 111 /* 112 * Called to reset things after an exception. 113 */ 114 115 #ifdef mkinit 116 INCLUDE "eval.h" 117 118 RESET { 119 evalskip = 0; 120 loopnest = 0; 121 funcnest = 0; 122 } 123 124 SHELLPROC { 125 exitstatus = 0; 126 } 127 #endif 128 129 130 131 /* 132 * The eval commmand. 133 */ 134 135 evalcmd(argc, argv) 136 char **argv; 137 { 138 char *p; 139 char *concat; 140 char **ap; 141 142 if (argc > 1) { 143 p = argv[1]; 144 if (argc > 2) { 145 STARTSTACKSTR(concat); 146 ap = argv + 2; 147 for (;;) { 148 while (*p) 149 STPUTC(*p++, concat); 150 if ((p = *ap++) == NULL) 151 break; 152 STPUTC(' ', concat); 153 } 154 STPUTC('\0', concat); 155 p = grabstackstr(concat); 156 } 157 evalstring(p); 158 } 159 return exitstatus; 160 } 161 162 163 /* 164 * Execute a command or commands contained in a string. 165 */ 166 167 void 168 evalstring(s) 169 char *s; 170 { 171 union node *n; 172 struct stackmark smark; 173 174 setstackmark(&smark); 175 setinputstring(s, 1); 176 while ((n = parsecmd(0)) != NEOF) { 177 evaltree(n, 0); 178 popstackmark(&smark); 179 } 180 popfile(); 181 popstackmark(&smark); 182 } 183 184 185 186 /* 187 * Evaluate a parse tree. The value is left in the global variable 188 * exitstatus. 189 */ 190 191 void 192 evaltree(n, flags) 193 union node *n; 194 { 195 if (n == NULL) { 196 TRACE(("evaltree(NULL) called\n")); 197 exitstatus = 0; 198 goto out; 199 } 200 displayhist = 1; /* show history substitutions done with fc */ 201 TRACE(("evaltree(0x%x: %d) called\n", (int)n, n->type)); 202 switch (n->type) { 203 case NSEMI: 204 evaltree(n->nbinary.ch1, 0); 205 if (evalskip) 206 goto out; 207 evaltree(n->nbinary.ch2, flags); 208 break; 209 case NAND: 210 evaltree(n->nbinary.ch1, EV_TESTED); 211 if (evalskip || exitstatus != 0) 212 goto out; 213 evaltree(n->nbinary.ch2, flags); 214 break; 215 case NOR: 216 evaltree(n->nbinary.ch1, EV_TESTED); 217 if (evalskip || exitstatus == 0) 218 goto out; 219 evaltree(n->nbinary.ch2, flags); 220 break; 221 case NREDIR: 222 expredir(n->nredir.redirect); 223 redirect(n->nredir.redirect, REDIR_PUSH); 224 evaltree(n->nredir.n, flags); 225 popredir(); 226 break; 227 case NSUBSHELL: 228 evalsubshell(n, flags); 229 break; 230 case NBACKGND: 231 evalsubshell(n, flags); 232 break; 233 case NIF: { 234 int status = 0; 235 236 evaltree(n->nif.test, EV_TESTED); 237 if (evalskip) 238 goto out; 239 if (exitstatus == 0) { 240 evaltree(n->nif.ifpart, flags); 241 status = exitstatus; 242 } else if (n->nif.elsepart) { 243 evaltree(n->nif.elsepart, flags); 244 status = exitstatus; 245 } 246 exitstatus = status; 247 break; 248 } 249 case NWHILE: 250 case NUNTIL: 251 evalloop(n); 252 break; 253 case NFOR: 254 evalfor(n); 255 break; 256 case NCASE: 257 evalcase(n, flags); 258 break; 259 case NDEFUN: 260 defun(n->narg.text, n->narg.next); 261 exitstatus = 0; 262 break; 263 case NNOT: 264 evaltree(n->nnot.com, EV_TESTED); 265 exitstatus = !exitstatus; 266 break; 267 268 case NPIPE: 269 evalpipe(n); 270 break; 271 case NCMD: 272 evalcommand(n, flags, (struct backcmd *)NULL); 273 break; 274 default: 275 out1fmt("Node type = %d\n", n->type); 276 flushout(&output); 277 break; 278 } 279 out: 280 if (pendingsigs) 281 dotrap(); 282 if ((flags & EV_EXIT) || (eflag && exitstatus && !(flags & EV_TESTED))) 283 exitshell(exitstatus); 284 } 285 286 287 STATIC void 288 evalloop(n) 289 union node *n; 290 { 291 int status; 292 293 loopnest++; 294 status = 0; 295 for (;;) { 296 evaltree(n->nbinary.ch1, EV_TESTED); 297 if (evalskip) { 298 skipping: if (evalskip == SKIPCONT && --skipcount <= 0) { 299 evalskip = 0; 300 continue; 301 } 302 if (evalskip == SKIPBREAK && --skipcount <= 0) 303 evalskip = 0; 304 break; 305 } 306 if (n->type == NWHILE) { 307 if (exitstatus != 0) 308 break; 309 } else { 310 if (exitstatus == 0) 311 break; 312 } 313 evaltree(n->nbinary.ch2, 0); 314 status = exitstatus; 315 if (evalskip) 316 goto skipping; 317 } 318 loopnest--; 319 exitstatus = status; 320 } 321 322 323 324 STATIC void 325 evalfor(n) 326 union node *n; 327 { 328 struct arglist arglist; 329 union node *argp; 330 struct strlist *sp; 331 struct stackmark smark; 332 333 setstackmark(&smark); 334 arglist.lastp = &arglist.list; 335 for (argp = n->nfor.args ; argp ; argp = argp->narg.next) { 336 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE); 337 if (evalskip) 338 goto out; 339 } 340 *arglist.lastp = NULL; 341 342 exitstatus = 0; 343 loopnest++; 344 for (sp = arglist.list ; sp ; sp = sp->next) { 345 setvar(n->nfor.var, sp->text, 0); 346 evaltree(n->nfor.body, 0); 347 if (evalskip) { 348 if (evalskip == SKIPCONT && --skipcount <= 0) { 349 evalskip = 0; 350 continue; 351 } 352 if (evalskip == SKIPBREAK && --skipcount <= 0) 353 evalskip = 0; 354 break; 355 } 356 } 357 loopnest--; 358 out: 359 popstackmark(&smark); 360 } 361 362 363 364 STATIC void 365 evalcase(n, flags) 366 union node *n; 367 { 368 union node *cp; 369 union node *patp; 370 struct arglist arglist; 371 struct stackmark smark; 372 373 setstackmark(&smark); 374 arglist.lastp = &arglist.list; 375 expandarg(n->ncase.expr, &arglist, EXP_TILDE); 376 for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) { 377 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) { 378 if (casematch(patp, arglist.list->text)) { 379 if (evalskip == 0) { 380 evaltree(cp->nclist.body, flags); 381 } 382 goto out; 383 } 384 } 385 } 386 out: 387 popstackmark(&smark); 388 } 389 390 391 392 /* 393 * Kick off a subshell to evaluate a tree. 394 */ 395 396 STATIC void 397 evalsubshell(n, flags) 398 union node *n; 399 { 400 struct job *jp; 401 int backgnd = (n->type == NBACKGND); 402 403 expredir(n->nredir.redirect); 404 jp = makejob(n, 1); 405 if (forkshell(jp, n, backgnd) == 0) { 406 if (backgnd) 407 flags &=~ EV_TESTED; 408 redirect(n->nredir.redirect, 0); 409 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */ 410 } 411 if (! backgnd) { 412 INTOFF; 413 exitstatus = waitforjob(jp); 414 INTON; 415 } 416 } 417 418 419 420 /* 421 * Compute the names of the files in a redirection list. 422 */ 423 424 STATIC void 425 expredir(n) 426 union node *n; 427 { 428 register union node *redir; 429 430 for (redir = n ; redir ; redir = redir->nfile.next) { 431 if (redir->type == NFROM 432 || redir->type == NTO 433 || redir->type == NAPPEND) { 434 struct arglist fn; 435 fn.lastp = &fn.list; 436 expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR); 437 redir->nfile.expfname = fn.list->text; 438 } 439 } 440 } 441 442 443 444 /* 445 * Evaluate a pipeline. All the processes in the pipeline are children 446 * of the process creating the pipeline. (This differs from some versions 447 * of the shell, which make the last process in a pipeline the parent 448 * of all the rest.) 449 */ 450 451 STATIC void 452 evalpipe(n) 453 union node *n; 454 { 455 struct job *jp; 456 struct nodelist *lp; 457 int pipelen; 458 int prevfd; 459 int pip[2]; 460 461 TRACE(("evalpipe(0x%x) called\n", (int)n)); 462 pipelen = 0; 463 for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) 464 pipelen++; 465 INTOFF; 466 jp = makejob(n, pipelen); 467 prevfd = -1; 468 for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) { 469 prehash(lp->n); 470 pip[1] = -1; 471 if (lp->next) { 472 if (pipe(pip) < 0) { 473 close(prevfd); 474 error("Pipe call failed"); 475 } 476 } 477 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) { 478 INTON; 479 if (prevfd > 0) { 480 close(0); 481 copyfd(prevfd, 0); 482 close(prevfd); 483 } 484 if (pip[1] >= 0) { 485 close(pip[0]); 486 if (pip[1] != 1) { 487 close(1); 488 copyfd(pip[1], 1); 489 close(pip[1]); 490 } 491 } 492 evaltree(lp->n, EV_EXIT); 493 } 494 if (prevfd >= 0) 495 close(prevfd); 496 prevfd = pip[0]; 497 close(pip[1]); 498 } 499 INTON; 500 if (n->npipe.backgnd == 0) { 501 INTOFF; 502 exitstatus = waitforjob(jp); 503 TRACE(("evalpipe: job done exit status %d\n", exitstatus)); 504 INTON; 505 } 506 } 507 508 509 510 /* 511 * Execute a command inside back quotes. If it's a builtin command, we 512 * want to save its output in a block obtained from malloc. Otherwise 513 * we fork off a subprocess and get the output of the command via a pipe. 514 * Should be called with interrupts off. 515 */ 516 517 void 518 evalbackcmd(n, result) 519 union node *n; 520 struct backcmd *result; 521 { 522 int pip[2]; 523 struct job *jp; 524 struct stackmark smark; /* unnecessary */ 525 526 setstackmark(&smark); 527 result->fd = -1; 528 result->buf = NULL; 529 result->nleft = 0; 530 result->jp = NULL; 531 exitstatus = 0; 532 if (n == NULL) 533 goto out; 534 if (n->type == NCMD) { 535 evalcommand(n, EV_BACKCMD, result); 536 } else { 537 if (pipe(pip) < 0) 538 error("Pipe call failed"); 539 jp = makejob(n, 1); 540 if (forkshell(jp, n, FORK_NOJOB) == 0) { 541 FORCEINTON; 542 close(pip[0]); 543 if (pip[1] != 1) { 544 close(1); 545 copyfd(pip[1], 1); 546 close(pip[1]); 547 } 548 evaltree(n, EV_EXIT); 549 } 550 close(pip[1]); 551 result->fd = pip[0]; 552 result->jp = jp; 553 } 554 out: 555 popstackmark(&smark); 556 TRACE(("evalbackcmd done: fd=%d buf=0x%x nleft=%d jp=0x%x\n", 557 result->fd, result->buf, result->nleft, result->jp)); 558 } 559 560 561 562 /* 563 * Execute a simple command. 564 */ 565 566 STATIC void 567 evalcommand(cmd, flags, backcmd) 568 union node *cmd; 569 struct backcmd *backcmd; 570 { 571 struct stackmark smark; 572 union node *argp; 573 struct arglist arglist; 574 struct arglist varlist; 575 char **argv; 576 int argc; 577 char **envp; 578 int varflag; 579 struct strlist *sp; 580 register char *p; 581 int mode; 582 int pip[2]; 583 struct cmdentry cmdentry; 584 struct job *jp; 585 struct jmploc jmploc; 586 struct jmploc *volatile savehandler; 587 char *volatile savecmdname; 588 volatile struct shparam saveparam; 589 struct localvar *volatile savelocalvars; 590 volatile int e; 591 char *lastarg; 592 593 /* First expand the arguments. */ 594 TRACE(("evalcommand(0x%x, %d) called\n", (int)cmd, flags)); 595 setstackmark(&smark); 596 arglist.lastp = &arglist.list; 597 varlist.lastp = &varlist.list; 598 varflag = 1; 599 for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) { 600 p = argp->narg.text; 601 if (varflag && is_name(*p)) { 602 do { 603 p++; 604 } while (is_in_name(*p)); 605 if (*p == '=') { 606 expandarg(argp, &varlist, EXP_VARTILDE); 607 continue; 608 } 609 } 610 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE); 611 varflag = 0; 612 } 613 *arglist.lastp = NULL; 614 *varlist.lastp = NULL; 615 expredir(cmd->ncmd.redirect); 616 argc = 0; 617 for (sp = arglist.list ; sp ; sp = sp->next) 618 argc++; 619 argv = stalloc(sizeof (char *) * (argc + 1)); 620 621 for (sp = arglist.list ; sp ; sp = sp->next) { 622 TRACE(("evalcommand arg: %s\n", sp->text)); 623 *argv++ = sp->text; 624 } 625 *argv = NULL; 626 lastarg = NULL; 627 if (iflag && funcnest == 0 && argc > 0) 628 lastarg = argv[-1]; 629 argv -= argc; 630 631 /* Print the command if xflag is set. */ 632 if (xflag) { 633 outc('+', &errout); 634 for (sp = varlist.list ; sp ; sp = sp->next) { 635 outc(' ', &errout); 636 out2str(sp->text); 637 } 638 for (sp = arglist.list ; sp ; sp = sp->next) { 639 outc(' ', &errout); 640 out2str(sp->text); 641 } 642 outc('\n', &errout); 643 flushout(&errout); 644 } 645 646 /* Now locate the command. */ 647 if (argc == 0) { 648 cmdentry.cmdtype = CMDBUILTIN; 649 cmdentry.u.index = BLTINCMD; 650 } else { 651 find_command(argv[0], &cmdentry, 1); 652 if (cmdentry.cmdtype == CMDUNKNOWN) { /* command not found */ 653 exitstatus = 2; 654 flushout(&errout); 655 return; 656 } 657 /* implement the bltin builtin here */ 658 if (cmdentry.cmdtype == CMDBUILTIN && cmdentry.u.index == BLTINCMD) { 659 for (;;) { 660 argv++; 661 if (--argc == 0) 662 break; 663 if ((cmdentry.u.index = find_builtin(*argv)) < 0) { 664 outfmt(&errout, "%s: not found\n", *argv); 665 exitstatus = 2; 666 flushout(&errout); 667 return; 668 } 669 if (cmdentry.u.index != BLTINCMD) 670 break; 671 } 672 } 673 } 674 675 /* Fork off a child process if necessary. */ 676 if (cmd->ncmd.backgnd 677 || cmdentry.cmdtype == CMDNORMAL && (flags & EV_EXIT) == 0 678 || (flags & EV_BACKCMD) != 0 679 && (cmdentry.cmdtype != CMDBUILTIN 680 || cmdentry.u.index == DOTCMD 681 || cmdentry.u.index == EVALCMD)) { 682 jp = makejob(cmd, 1); 683 mode = cmd->ncmd.backgnd; 684 if (flags & EV_BACKCMD) { 685 mode = FORK_NOJOB; 686 if (pipe(pip) < 0) 687 error("Pipe call failed"); 688 } 689 if (forkshell(jp, cmd, mode) != 0) 690 goto parent; /* at end of routine */ 691 if (flags & EV_BACKCMD) { 692 FORCEINTON; 693 close(pip[0]); 694 if (pip[1] != 1) { 695 close(1); 696 copyfd(pip[1], 1); 697 close(pip[1]); 698 } 699 } 700 flags |= EV_EXIT; 701 } 702 703 /* This is the child process if a fork occurred. */ 704 /* Execute the command. */ 705 if (cmdentry.cmdtype == CMDFUNCTION) { 706 trputs("Shell function: "); trargs(argv); 707 redirect(cmd->ncmd.redirect, REDIR_PUSH); 708 saveparam = shellparam; 709 shellparam.malloc = 0; 710 shellparam.nparam = argc - 1; 711 shellparam.p = argv + 1; 712 shellparam.optnext = NULL; 713 INTOFF; 714 savelocalvars = localvars; 715 localvars = NULL; 716 INTON; 717 if (setjmp(jmploc.loc)) { 718 if (exception == EXSHELLPROC) 719 freeparam((struct shparam *)&saveparam); 720 else { 721 freeparam(&shellparam); 722 shellparam = saveparam; 723 } 724 poplocalvars(); 725 localvars = savelocalvars; 726 handler = savehandler; 727 longjmp(handler->loc, 1); 728 } 729 savehandler = handler; 730 handler = &jmploc; 731 for (sp = varlist.list ; sp ; sp = sp->next) 732 mklocal(sp->text); 733 funcnest++; 734 evaltree(cmdentry.u.func, 0); 735 funcnest--; 736 INTOFF; 737 poplocalvars(); 738 localvars = savelocalvars; 739 freeparam(&shellparam); 740 shellparam = saveparam; 741 handler = savehandler; 742 popredir(); 743 INTON; 744 if (evalskip == SKIPFUNC) { 745 evalskip = 0; 746 skipcount = 0; 747 } 748 if (flags & EV_EXIT) 749 exitshell(exitstatus); 750 } else if (cmdentry.cmdtype == CMDBUILTIN) { 751 trputs("builtin command: "); trargs(argv); 752 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH; 753 if (flags == EV_BACKCMD) { 754 memout.nleft = 0; 755 memout.nextc = memout.buf; 756 memout.bufsize = 64; 757 mode |= REDIR_BACKQ; 758 } 759 redirect(cmd->ncmd.redirect, mode); 760 savecmdname = commandname; 761 cmdenviron = varlist.list; 762 e = -1; 763 if (setjmp(jmploc.loc)) { 764 e = exception; 765 exitstatus = (e == EXINT)? SIGINT+128 : 2; 766 goto cmddone; 767 } 768 savehandler = handler; 769 handler = &jmploc; 770 commandname = argv[0]; 771 argptr = argv + 1; 772 optptr = NULL; /* initialize nextopt */ 773 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv); 774 flushall(); 775 cmddone: 776 out1 = &output; 777 out2 = &errout; 778 freestdout(); 779 if (e != EXSHELLPROC) { 780 commandname = savecmdname; 781 if (flags & EV_EXIT) { 782 exitshell(exitstatus); 783 } 784 } 785 handler = savehandler; 786 if (e != -1) { 787 if (e != EXERROR || cmdentry.u.index == BLTINCMD 788 || cmdentry.u.index == DOTCMD 789 || cmdentry.u.index == EVALCMD 790 || cmdentry.u.index == HISTCMD 791 || cmdentry.u.index == EXECCMD) 792 exraise(e); 793 FORCEINTON; 794 } 795 if (cmdentry.u.index != EXECCMD) 796 popredir(); 797 if (flags == EV_BACKCMD) { 798 backcmd->buf = memout.buf; 799 backcmd->nleft = memout.nextc - memout.buf; 800 memout.buf = NULL; 801 } 802 } else { 803 trputs("normal command: "); trargs(argv); 804 clearredir(); 805 redirect(cmd->ncmd.redirect, 0); 806 if (varlist.list) { 807 p = stalloc(strlen(pathval()) + 1); 808 scopy(pathval(), p); 809 } else { 810 p = pathval(); 811 } 812 for (sp = varlist.list ; sp ; sp = sp->next) 813 setvareq(sp->text, VEXPORT|VSTACK); 814 envp = environment(); 815 shellexec(argv, envp, p, cmdentry.u.index); 816 /*NOTREACHED*/ 817 } 818 goto out; 819 820 parent: /* parent process gets here (if we forked) */ 821 if (mode == 0) { /* argument to fork */ 822 INTOFF; 823 exitstatus = waitforjob(jp); 824 INTON; 825 } else if (mode == 2) { 826 backcmd->fd = pip[0]; 827 close(pip[1]); 828 backcmd->jp = jp; 829 } 830 831 out: 832 if (lastarg) 833 setvar("_", lastarg, 0); 834 popstackmark(&smark); 835 } 836 837 838 839 /* 840 * Search for a command. This is called before we fork so that the 841 * location of the command will be available in the parent as well as 842 * the child. The check for "goodname" is an overly conservative 843 * check that the name will not be subject to expansion. 844 */ 845 846 STATIC void 847 prehash(n) 848 union node *n; 849 { 850 struct cmdentry entry; 851 852 if (n->type == NCMD && goodname(n->ncmd.args->narg.text)) 853 find_command(n->ncmd.args->narg.text, &entry, 0); 854 } 855 856 857 858 /* 859 * Builtin commands. Builtin commands whose functions are closely 860 * tied to evaluation are implemented here. 861 */ 862 863 /* 864 * No command given, or a bltin command with no arguments. Set the 865 * specified variables. 866 */ 867 868 bltincmd(argc, argv) char **argv; { 869 listsetvar(cmdenviron); 870 return exitstatus; 871 } 872 873 874 /* 875 * Handle break and continue commands. Break, continue, and return are 876 * all handled by setting the evalskip flag. The evaluation routines 877 * above all check this flag, and if it is set they start skipping 878 * commands rather than executing them. The variable skipcount is 879 * the number of loops to break/continue, or the number of function 880 * levels to return. (The latter is always 1.) It should probably 881 * be an error to break out of more loops than exist, but it isn't 882 * in the standard shell so we don't make it one here. 883 */ 884 885 breakcmd(argc, argv) char **argv; { 886 int n; 887 888 n = 1; 889 if (argc > 1) 890 n = number(argv[1]); 891 if (n > loopnest) 892 n = loopnest; 893 if (n > 0) { 894 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK; 895 skipcount = n; 896 } 897 return 0; 898 } 899 900 901 /* 902 * The return command. 903 */ 904 905 returncmd(argc, argv) char **argv; { 906 int ret; 907 908 ret = exitstatus; 909 if (argc > 1) 910 ret = number(argv[1]); 911 if (funcnest) { 912 evalskip = SKIPFUNC; 913 skipcount = 1; 914 } 915 return ret; 916 } 917 918 919 truecmd(argc, argv) char **argv; { 920 return 0; 921 } 922 923 924 execcmd(argc, argv) char **argv; { 925 if (argc > 1) { 926 iflag = 0; /* exit on error */ 927 mflag = 0; 928 optschanged(); 929 shellexec(argv + 1, environment(), pathval(), 0); 930 931 } 932 return 0; 933 } 934