bin/sh/eval.c

   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  * @(#)eval.c   8.9 (Berkeley) 6/8/95
  37  * $FreeBSD: src/bin/sh/eval.c,v 1.27.2.5 2002/08/27 01:36:28 tjr Exp $
  38  * $DragonFly: src/bin/sh/eval.c,v 1.5 2006/05/12 01:56:11 y0netan1 Exp $
  39  */
  40
  41 #include <sys/wait.h> /* For WIFSIGNALED(status) */
  42
  43 #include <errno.h>
  44 #include <paths.h>
  45 #include <signal.h>
  46 #include <stdlib.h>
  47 #include <unistd.h>
  48
  49 /*
  50  * Evaluate a command.
  51  */
  52
  53 #include "shell.h"
  54 #include "nodes.h"
  55 #include "syntax.h"
  56 #include "expand.h"
  57 #include "parser.h"
  58 #include "jobs.h"
  59 #include "eval.h"
  60 #include "builtins.h"
  61 #include "options.h"
  62 #include "exec.h"
  63 #include "redir.h"
  64 #include "input.h"
  65 #include "output.h"
  66 #include "trap.h"
  67 #include "var.h"
  68 #include "memalloc.h"
  69 #include "error.h"
  70 #include "show.h"
  71 #include "mystring.h"
  72 #ifndef NO_HISTORY
  73 #include "myhistedit.h"
  74 #endif
  75
  76
  77 /* flags in argument to evaltree */
  78 #define EV_EXIT 01              /* exit after evaluating tree */
  79 #define EV_TESTED 02            /* exit status is checked; ignore -e flag */
  80 #define EV_BACKCMD 04           /* command executing within back quotes */
  81
  82 MKINIT int evalskip;            /* set if we are skipping commands */
  83 STATIC int skipcount;           /* number of levels to skip */
  84 MKINIT int loopnest;            /* current loop nesting level */
  85 int funcnest;                   /* depth of function calls */
  86
  87
  88 const char *commandname;
  89 struct strlist *cmdenviron;
  90 int exitstatus;                 /* exit status of last command */
  91 int oexitstatus;                /* saved exit status */
  92
  93
  94 STATIC void evalloop(union node *);
  95 STATIC void evalfor(union node *);
  96 STATIC void evalcase(union node *, int);
  97 STATIC void evalsubshell(union node *, int);
  98 STATIC void expredir(union node *);
  99 STATIC void evalpipe(union node *);
 100 STATIC void evalcommand(union node *, int, struct backcmd *);
 101 STATIC void prehash(union node *);
 102
 103
 104 /*
 105  * Called to reset things after an exception.
 106  */
 107
 108 #ifdef mkinit
 109 INCLUDE "eval.h"
 110
 111 RESET {
 112         evalskip = 0;
 113         loopnest = 0;
 114         funcnest = 0;
 115 }
 116
 117 SHELLPROC {
 118         exitstatus = 0;
 119 }
 120 #endif
 121
 122
 123
 124 /*
 125  * The eval command.
 126  */
 127
 128 int
 129 evalcmd(int argc, char **argv)
 130 {
 131         char *p;
 132         char *concat;
 133         char **ap;
 134
 135         if (argc > 1) {
 136                 p = argv[1];
 137                 if (argc > 2) {
 138                         STARTSTACKSTR(concat);
 139                         ap = argv + 2;
 140                         for (;;) {
 141                                 while (*p)
 142                                         STPUTC(*p++, concat);
 143                                 if ((p = *ap++) == NULL)
 144                                         break;
 145                                 STPUTC(' ', concat);
 146                         }
 147                         STPUTC('\0', concat);
 148                         p = grabstackstr(concat);
 149                 }
 150                 evalstring(p);
 151         }
 152         return exitstatus;
 153 }
 154
 155
 156 /*
 157  * Execute a command or commands contained in a string.
 158  */
 159
 160 void
 161 evalstring(char *s)
 162 {
 163         union node *n;
 164         struct stackmark smark;
 165
 166         setstackmark(&smark);
 167         setinputstring(s, 1);
 168         while ((n = parsecmd(0)) != NEOF) {
 169                 evaltree(n, 0);
 170                 popstackmark(&smark);
 171         }
 172         popfile();
 173         popstackmark(&smark);
 174 }
 175
 176
 177
 178 /*
 179  * Evaluate a parse tree.  The value is left in the global variable
 180  * exitstatus.
 181  */
 182
 183 void
 184 evaltree(union node *n, int flags)
 185 {
 186         if (n == NULL) {
 187                 TRACE(("evaltree(NULL) called\n"));
 188                 exitstatus = 0;
 189                 goto out;
 190         }
 191 #ifndef NO_HISTORY
 192         displayhist = 1;        /* show history substitutions done with fc */
 193 #endif
 194         TRACE(("evaltree(0x%lx: %d) called\n", (long)n, n->type));
 195         switch (n->type) {
 196         case NSEMI:
 197                 evaltree(n->nbinary.ch1, 0);
 198                 if (evalskip)
 199                         goto out;
 200                 evaltree(n->nbinary.ch2, flags);
 201                 break;
 202         case NAND:
 203                 evaltree(n->nbinary.ch1, EV_TESTED);
 204                 if (evalskip || exitstatus != 0) {
 205                         goto out;
 206                 }
 207                 evaltree(n->nbinary.ch2, flags);
 208                 break;
 209         case NOR:
 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 NREDIR:
 216                 expredir(n->nredir.redirect);
 217                 redirect(n->nredir.redirect, REDIR_PUSH);
 218                 evaltree(n->nredir.n, flags);
 219                 popredir();
 220                 break;
 221         case NSUBSHELL:
 222                 evalsubshell(n, flags);
 223                 break;
 224         case NBACKGND:
 225                 evalsubshell(n, flags);
 226                 break;
 227         case NIF: {
 228                 evaltree(n->nif.test, EV_TESTED);
 229                 if (evalskip)
 230                         goto out;
 231                 if (exitstatus == 0)
 232                         evaltree(n->nif.ifpart, flags);
 233                 else if (n->nif.elsepart)
 234                         evaltree(n->nif.elsepart, flags);
 235                 else
 236                         exitstatus = 0;
 237                 break;
 238         }
 239         case NWHILE:
 240         case NUNTIL:
 241                 evalloop(n);
 242                 break;
 243         case NFOR:
 244                 evalfor(n);
 245                 break;
 246         case NCASE:
 247                 evalcase(n, flags);
 248                 break;
 249         case NDEFUN:
 250                 defun(n->narg.text, n->narg.next);
 251                 exitstatus = 0;
 252                 break;
 253         case NNOT:
 254                 evaltree(n->nnot.com, EV_TESTED);
 255                 exitstatus = !exitstatus;
 256                 break;
 257
 258         case NPIPE:
 259                 evalpipe(n);
 260                 break;
 261         case NCMD:
 262                 evalcommand(n, flags, (struct backcmd *)NULL);
 263                 break;
 264         default:
 265                 out1fmt("Node type = %d\n", n->type);
 266                 flushout(&output);
 267                 break;
 268         }
 269 out:
 270         if (pendingsigs)
 271                 dotrap();
 272         if ((flags & EV_EXIT) || (eflag && exitstatus
 273             && !(flags & EV_TESTED) && (n->type == NCMD ||
 274             n->type == NSUBSHELL)))
 275                 exitshell(exitstatus);
 276 }
 277
 278
 279 STATIC void
 280 evalloop(union node *n)
 281 {
 282         int status;
 283
 284         loopnest++;
 285         status = 0;
 286         for (;;) {
 287                 evaltree(n->nbinary.ch1, EV_TESTED);
 288                 if (evalskip) {
 289 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
 290                                 evalskip = 0;
 291                                 continue;
 292                         }
 293                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 294                                 evalskip = 0;
 295                         break;
 296                 }
 297                 if (n->type == NWHILE) {
 298                         if (exitstatus != 0)
 299                                 break;
 300                 } else {
 301                         if (exitstatus == 0)
 302                                 break;
 303                 }
 304                 evaltree(n->nbinary.ch2, 0);
 305                 status = exitstatus;
 306                 if (evalskip)
 307                         goto skipping;
 308         }
 309         loopnest--;
 310         exitstatus = status;
 311 }
 312
 313
 314
 315 STATIC void
 316 evalfor(union node *n)
 317 {
 318         struct arglist arglist;
 319         union node *argp;
 320         struct strlist *sp;
 321         struct stackmark smark;
 322
 323         setstackmark(&smark);
 324         arglist.lastp = &arglist.list;
 325         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 326                 oexitstatus = exitstatus;
 327                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 328                 if (evalskip)
 329                         goto out;
 330         }
 331         *arglist.lastp = NULL;
 332
 333         exitstatus = 0;
 334         loopnest++;
 335         for (sp = arglist.list ; sp ; sp = sp->next) {
 336                 setvar(n->nfor.var, sp->text, 0);
 337                 evaltree(n->nfor.body, 0);
 338                 if (evalskip) {
 339                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 340                                 evalskip = 0;
 341                                 continue;
 342                         }
 343                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 344                                 evalskip = 0;
 345                         break;
 346                 }
 347         }
 348         loopnest--;
 349 out:
 350         popstackmark(&smark);
 351 }
 352
 353
 354
 355 STATIC void
 356 evalcase(union node *n, int flags)
 357 {
 358         union node *cp;
 359         union node *patp;
 360         struct arglist arglist;
 361         struct stackmark smark;
 362
 363         setstackmark(&smark);
 364         arglist.lastp = &arglist.list;
 365         oexitstatus = exitstatus;
 366         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 367         for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
 368                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 369                         if (casematch(patp, arglist.list->text)) {
 370                                 if (evalskip == 0) {
 371                                         evaltree(cp->nclist.body, flags);
 372                                 }
 373                                 goto out;
 374                         }
 375                 }
 376         }
 377 out:
 378         popstackmark(&smark);
 379 }
 380
 381
 382
 383 /*
 384  * Kick off a subshell to evaluate a tree.
 385  */
 386
 387 STATIC void
 388 evalsubshell(union node *n, int flags)
 389 {
 390         struct job *jp;
 391         int backgnd = (n->type == NBACKGND);
 392
 393         expredir(n->nredir.redirect);
 394         jp = makejob(n, 1);
 395         if (forkshell(jp, n, backgnd) == 0) {
 396                 if (backgnd)
 397                         flags &=~ EV_TESTED;
 398                 redirect(n->nredir.redirect, 0);
 399                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 400         }
 401         if (! backgnd) {
 402                 INTOFF;
 403                 exitstatus = waitforjob(jp, (int *)NULL);
 404                 INTON;
 405         }
 406 }
 407
 408
 409
 410 /*
 411  * Compute the names of the files in a redirection list.
 412  */
 413
 414 STATIC void
 415 expredir(union node *n)
 416 {
 417         union node *redir;
 418
 419         for (redir = n ; redir ; redir = redir->nfile.next) {
 420                 struct arglist fn;
 421                 fn.lastp = &fn.list;
 422                 oexitstatus = exitstatus;
 423                 switch (redir->type) {
 424                 case NFROM:
 425                 case NTO:
 426                 case NFROMTO:
 427                 case NAPPEND:
 428                 case NCLOBBER:
 429                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 430                         redir->nfile.expfname = fn.list->text;
 431                         break;
 432                 case NFROMFD:
 433                 case NTOFD:
 434                         if (redir->ndup.vname) {
 435                                 expandarg(redir->ndup.vname, &fn, EXP_FULL | EXP_TILDE);
 436                                 fixredir(redir, fn.list->text, 1);
 437                         }
 438                         break;
 439                 }
 440         }
 441 }
 442
 443
 444
 445 /*
 446  * Evaluate a pipeline.  All the processes in the pipeline are children
 447  * of the process creating the pipeline.  (This differs from some versions
 448  * of the shell, which make the last process in a pipeline the parent
 449  * of all the rest.)
 450  */
 451
 452 STATIC void
 453 evalpipe(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%lx) called\n", (long)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: %s", strerror(errno));
 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                                 if (!(prevfd >= 0 && pip[0] == 0))
 486                                         close(pip[0]);
 487                                 if (pip[1] != 1) {
 488                                         close(1);
 489                                         copyfd(pip[1], 1);
 490                                         close(pip[1]);
 491                                 }
 492                         }
 493                         evaltree(lp->n, EV_EXIT);
 494                 }
 495                 if (prevfd >= 0)
 496                         close(prevfd);
 497                 prevfd = pip[0];
 498                 close(pip[1]);
 499         }
 500         INTON;
 501         if (n->npipe.backgnd == 0) {
 502                 INTOFF;
 503                 exitstatus = waitforjob(jp, (int *)NULL);
 504                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 505                 INTON;
 506         }
 507 }
 508
 509
 510
 511 /*
 512  * Execute a command inside back quotes.  If it's a builtin command, we
 513  * want to save its output in a block obtained from malloc.  Otherwise
 514  * we fork off a subprocess and get the output of the command via a pipe.
 515  * Should be called with interrupts off.
 516  */
 517
 518 void
 519 evalbackcmd(union node *n, struct backcmd *result)
 520 {
 521         int pip[2];
 522         struct job *jp;
 523         struct stackmark smark;         /* unnecessary */
 524
 525         setstackmark(&smark);
 526         result->fd = -1;
 527         result->buf = NULL;
 528         result->nleft = 0;
 529         result->jp = NULL;
 530         if (n == NULL) {
 531                 exitstatus = 0;
 532                 goto out;
 533         }
 534         if (n->type == NCMD) {
 535                 exitstatus = oexitstatus;
 536                 evalcommand(n, EV_BACKCMD, result);
 537         } else {
 538                 exitstatus = 0;
 539                 if (pipe(pip) < 0)
 540                         error("Pipe call failed: %s", strerror(errno));
 541                 jp = makejob(n, 1);
 542                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 543                         FORCEINTON;
 544                         close(pip[0]);
 545                         if (pip[1] != 1) {
 546                                 close(1);
 547                                 copyfd(pip[1], 1);
 548                                 close(pip[1]);
 549                         }
 550                         evaltree(n, EV_EXIT);
 551                 }
 552                 close(pip[1]);
 553                 result->fd = pip[0];
 554                 result->jp = jp;
 555         }
 556 out:
 557         popstackmark(&smark);
 558         TRACE(("evalbackcmd done: fd=%d buf=0x%x nleft=%d jp=0x%x\n",
 559                 result->fd, result->buf, result->nleft, result->jp));
 560 }
 561
 562
 563
 564 /*
 565  * Execute a simple command.
 566  */
 567
 568 STATIC void
 569 evalcommand(union node *cmd, int flags, 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         int mode;
 581         int pip[2];
 582         struct cmdentry cmdentry;
 583         struct job *jp;
 584         struct jmploc jmploc;
 585         struct jmploc *volatile savehandler;
 586         const char *volatile savecmdname;
 587         volatile struct shparam saveparam;
 588         struct localvar *volatile savelocalvars;
 589         volatile int e;
 590         char *lastarg;
 591         int realstatus;
 592         int do_clearcmdentry;
 593 #if __GNUC__
 594         /* Avoid longjmp clobbering */
 595         (void) &argv;
 596         (void) &argc;
 597         (void) &lastarg;
 598         (void) &flags;
 599         (void) &do_clearcmdentry;
 600 #endif
 601
 602         /* First expand the arguments. */
 603         TRACE(("evalcommand(0x%lx, %d) called\n", (long)cmd, flags));
 604         setstackmark(&smark);
 605         arglist.lastp = &arglist.list;
 606         varlist.lastp = &varlist.list;
 607         varflag = 1;
 608         do_clearcmdentry = 0;
 609         oexitstatus = exitstatus;
 610         exitstatus = 0;
 611         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 612                 char *p = argp->narg.text;
 613                 if (varflag && is_name(*p)) {
 614                         do {
 615                                 p++;
 616                         } while (is_in_name(*p));
 617                         if (*p == '=') {
 618                                 expandarg(argp, &varlist, EXP_VARTILDE);
 619                                 continue;
 620                         }
 621                 }
 622                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 623                 varflag = 0;
 624         }
 625         *arglist.lastp = NULL;
 626         *varlist.lastp = NULL;
 627         expredir(cmd->ncmd.redirect);
 628         argc = 0;
 629         for (sp = arglist.list ; sp ; sp = sp->next)
 630                 argc++;
 631         argv = stalloc(sizeof (char *) * (argc + 1));
 632
 633         for (sp = arglist.list ; sp ; sp = sp->next) {
 634                 TRACE(("evalcommand arg: %s\n", sp->text));
 635                 *argv++ = sp->text;
 636         }
 637         *argv = NULL;
 638         lastarg = NULL;
 639         if (iflag && funcnest == 0 && argc > 0)
 640                 lastarg = argv[-1];
 641         argv -= argc;
 642
 643         /* Print the command if xflag is set. */
 644         if (xflag) {
 645                 outc('+', &errout);
 646                 for (sp = varlist.list ; sp ; sp = sp->next) {
 647                         outc(' ', &errout);
 648                         out2str(sp->text);
 649                 }
 650                 for (sp = arglist.list ; sp ; sp = sp->next) {
 651                         outc(' ', &errout);
 652                         out2str(sp->text);
 653                 }
 654                 outc('\n', &errout);
 655                 flushout(&errout);
 656         }
 657
 658         /* Now locate the command. */
 659         if (argc == 0) {
 660                 cmdentry.cmdtype = CMDBUILTIN;
 661                 cmdentry.u.index = BLTINCMD;
 662         } else {
 663                 static const char PATH[] = "PATH=";
 664                 const char *path = pathval();
 665
 666                 /*
 667                  * Modify the command lookup path, if a PATH= assignment
 668                  * is present
 669                  */
 670                 for (sp = varlist.list ; sp ; sp = sp->next)
 671                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 672                                 path = sp->text + sizeof(PATH) - 1;
 673                                 /*
 674                                  * On `PATH=... command`, we need to make
 675                                  * sure that the command isn't using the
 676                                  * non-updated hash table of the outer PATH
 677                                  * setting and we need to make sure that
 678                                  * the hash table isn't filled with items
 679                                  * from the temporary setting.
 680                                  *
 681                                  * It would be better to forbit using and
 682                                  * updating the table while this command
 683                                  * runs, by the command finding mechanism
 684                                  * is heavily integrated with hash handling,
 685                                  * so we just delete the hash before and after
 686                                  * the command runs. Partly deleting like
 687                                  * changepatch() does doesn't seem worth the
 688                                  * bookinging effort, since most such runs add
 689                                  * diretories in front of the new PATH.
 690                                  */
 691                                 clearcmdentry(0);
 692                                 do_clearcmdentry = 1;
 693                         }
 694
 695                 find_command(argv[0], &cmdentry, 1, path);
 696                 if (cmdentry.cmdtype == CMDUNKNOWN) {   /* command not found */
 697                         exitstatus = 127;
 698                         flushout(&errout);
 699                         return;
 700                 }
 701                 /* implement the bltin builtin here */
 702                 if (cmdentry.cmdtype == CMDBUILTIN && cmdentry.u.index == BLTINCMD) {
 703                         for (;;) {
 704                                 argv++;
 705                                 if (--argc == 0)
 706                                         break;
 707                                 if ((cmdentry.u.index = find_builtin(*argv)) < 0) {
 708                                         outfmt(&errout, "%s: not found\n", *argv);
 709                                         exitstatus = 127;
 710                                         flushout(&errout);
 711                                         return;
 712                                 }
 713                                 if (cmdentry.u.index != BLTINCMD)
 714                                         break;
 715                         }
 716                 }
 717         }
 718
 719         /* Fork off a child process if necessary. */
 720         if (cmd->ncmd.backgnd
 721          || (cmdentry.cmdtype == CMDNORMAL
 722             && ((flags & EV_EXIT) == 0 || Tflag))
 723          || ((flags & EV_BACKCMD) != 0
 724             && (cmdentry.cmdtype != CMDBUILTIN
 725                  || cmdentry.u.index == CDCMD
 726                  || cmdentry.u.index == DOTCMD
 727                  || cmdentry.u.index == EVALCMD))
 728          || (cmdentry.cmdtype == CMDBUILTIN &&
 729             cmdentry.u.index == COMMANDCMD)) {
 730                 jp = makejob(cmd, 1);
 731                 mode = cmd->ncmd.backgnd;
 732                 if (flags & EV_BACKCMD) {
 733                         mode = FORK_NOJOB;
 734                         if (pipe(pip) < 0)
 735                                 error("Pipe call failed: %s", strerror(errno));
 736                 }
 737                 if (forkshell(jp, cmd, mode) != 0)
 738                         goto parent;    /* at end of routine */
 739                 if (flags & EV_BACKCMD) {
 740                         FORCEINTON;
 741                         close(pip[0]);
 742                         if (pip[1] != 1) {
 743                                 close(1);
 744                                 copyfd(pip[1], 1);
 745                                 close(pip[1]);
 746                         }
 747                 }
 748                 flags |= EV_EXIT;
 749         }
 750
 751         /* This is the child process if a fork occurred. */
 752         /* Execute the command. */
 753         if (cmdentry.cmdtype == CMDFUNCTION) {
 754 #ifdef DEBUG
 755                 trputs("Shell function:  ");  trargs(argv);
 756 #endif
 757                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
 758                 saveparam = shellparam;
 759                 shellparam.malloc = 0;
 760                 shellparam.reset = 1;
 761                 shellparam.nparam = argc - 1;
 762                 shellparam.p = argv + 1;
 763                 shellparam.optnext = NULL;
 764                 INTOFF;
 765                 savelocalvars = localvars;
 766                 localvars = NULL;
 767                 INTON;
 768                 if (setjmp(jmploc.loc)) {
 769                         if (exception == EXSHELLPROC)
 770                                 freeparam((struct shparam *)&saveparam);
 771                         else {
 772                                 freeparam(&shellparam);
 773                                 shellparam = saveparam;
 774                         }
 775                         poplocalvars();
 776                         localvars = savelocalvars;
 777                         handler = savehandler;
 778                         longjmp(handler->loc, 1);
 779                 }
 780                 savehandler = handler;
 781                 handler = &jmploc;
 782                 for (sp = varlist.list ; sp ; sp = sp->next)
 783                         mklocal(sp->text);
 784                 funcnest++;
 785                 if (flags & EV_TESTED)
 786                         evaltree(cmdentry.u.func, EV_TESTED);
 787                 else
 788                         evaltree(cmdentry.u.func, 0);
 789                 funcnest--;
 790                 INTOFF;
 791                 poplocalvars();
 792                 localvars = savelocalvars;
 793                 freeparam(&shellparam);
 794                 shellparam = saveparam;
 795                 handler = savehandler;
 796                 popredir();
 797                 INTON;
 798                 if (evalskip == SKIPFUNC) {
 799                         evalskip = 0;
 800                         skipcount = 0;
 801                 }
 802                 if (flags & EV_EXIT)
 803                         exitshell(exitstatus);
 804         } else if (cmdentry.cmdtype == CMDBUILTIN) {
 805 #ifdef DEBUG
 806                 trputs("builtin command:  ");  trargs(argv);
 807 #endif
 808                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
 809                 if (flags == EV_BACKCMD) {
 810                         memout.nleft = 0;
 811                         memout.nextc = memout.buf;
 812                         memout.bufsize = 64;
 813                         mode |= REDIR_BACKQ;
 814                 }
 815                 redirect(cmd->ncmd.redirect, mode);
 816                 savecmdname = commandname;
 817                 cmdenviron = varlist.list;
 818                 e = -1;
 819                 if (setjmp(jmploc.loc)) {
 820                         e = exception;
 821                         exitstatus = (e == EXINT)? SIGINT+128 : 2;
 822                         goto cmddone;
 823                 }
 824                 savehandler = handler;
 825                 handler = &jmploc;
 826                 commandname = argv[0];
 827                 argptr = argv + 1;
 828                 optptr = NULL;                  /* initialize nextopt */
 829                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
 830                 flushall();
 831 cmddone:
 832                 cmdenviron = NULL;
 833                 out1 = &output;
 834                 out2 = &errout;
 835                 freestdout();
 836                 if (e != EXSHELLPROC) {
 837                         commandname = savecmdname;
 838                         if (flags & EV_EXIT) {
 839                                 exitshell(exitstatus);
 840                         }
 841                 }
 842                 handler = savehandler;
 843                 if (e != -1) {
 844                         if ((e != EXERROR && e != EXEXEC)
 845                            || cmdentry.u.index == BLTINCMD
 846                            || cmdentry.u.index == DOTCMD
 847                            || cmdentry.u.index == EVALCMD
 848 #ifndef NO_HISTORY
 849                            || cmdentry.u.index == HISTCMD
 850 #endif
 851                            || cmdentry.u.index == EXECCMD
 852                            || cmdentry.u.index == COMMANDCMD)
 853                                 exraise(e);
 854                         FORCEINTON;
 855                 }
 856                 if (cmdentry.u.index != EXECCMD)
 857                         popredir();
 858                 if (flags == EV_BACKCMD) {
 859                         backcmd->buf = memout.buf;
 860                         backcmd->nleft = memout.nextc - memout.buf;
 861                         memout.buf = NULL;
 862                 }
 863         } else {
 864 #ifdef DEBUG
 865                 trputs("normal command:  ");  trargs(argv);
 866 #endif
 867                 clearredir();
 868                 redirect(cmd->ncmd.redirect, 0);
 869                 for (sp = varlist.list ; sp ; sp = sp->next)
 870                         setvareq(sp->text, VEXPORT|VSTACK);
 871                 envp = environment();
 872                 shellexec(argv, envp, pathval(), cmdentry.u.index);
 873                 /*NOTREACHED*/
 874         }
 875         goto out;
 876
 877 parent: /* parent process gets here (if we forked) */
 878         if (mode == 0) {        /* argument to fork */
 879                 INTOFF;
 880                 exitstatus = waitforjob(jp, &realstatus);
 881                 INTON;
 882                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
 883                         evalskip = SKIPBREAK;
 884                         skipcount = loopnest;
 885                 }
 886         } else if (mode == 2) {
 887                 backcmd->fd = pip[0];
 888                 close(pip[1]);
 889                 backcmd->jp = jp;
 890         }
 891
 892 out:
 893         if (lastarg)
 894                 setvar("_", lastarg, 0);
 895         if (do_clearcmdentry)
 896                 clearcmdentry(0);
 897         popstackmark(&smark);
 898 }
 899
 900
 901
 902 /*
 903  * Search for a command.  This is called before we fork so that the
 904  * location of the command will be available in the parent as well as
 905  * the child.  The check for "goodname" is an overly conservative
 906  * check that the name will not be subject to expansion.
 907  */
 908
 909 STATIC void
 910 prehash(union node *n)
 911 {
 912         struct cmdentry entry;
 913
 914         if (n->type == NCMD && n->ncmd.args)
 915                 if (goodname(n->ncmd.args->narg.text))
 916                         find_command(n->ncmd.args->narg.text, &entry, 0,
 917                                      pathval());
 918 }
 919
 920
 921
 922 /*
 923  * Builtin commands.  Builtin commands whose functions are closely
 924  * tied to evaluation are implemented here.
 925  */
 926
 927 /*
 928  * No command given, or a bltin command with no arguments.  Set the
 929  * specified variables.
 930  */
 931
 932 int
 933 bltincmd(int argc __unused, char **argv __unused)
 934 {
 935         listsetvar(cmdenviron);
 936         /*
 937          * Preserve exitstatus of a previous possible redirection
 938          * as POSIX mandates
 939          */
 940         return exitstatus;
 941 }
 942
 943
 944 /*
 945  * Handle break and continue commands.  Break, continue, and return are
 946  * all handled by setting the evalskip flag.  The evaluation routines
 947  * above all check this flag, and if it is set they start skipping
 948  * commands rather than executing them.  The variable skipcount is
 949  * the number of loops to break/continue, or the number of function
 950  * levels to return.  (The latter is always 1.)  It should probably
 951  * be an error to break out of more loops than exist, but it isn't
 952  * in the standard shell so we don't make it one here.
 953  */
 954
 955 int
 956 breakcmd(int argc, char **argv)
 957 {
 958         int n = argc > 1 ? number(argv[1]) : 1;
 959
 960         if (n > loopnest)
 961                 n = loopnest;
 962         if (n > 0) {
 963                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
 964                 skipcount = n;
 965         }
 966         return 0;
 967 }
 968
 969 /*
 970  * The `command' command.
 971  */
 972 int
 973 commandcmd(int argc, char **argv)
 974 {
 975         static char stdpath[] = _PATH_STDPATH;
 976         struct jmploc loc, *old;
 977         struct strlist *sp;
 978         const char *path;
 979         int ch;
 980
 981         for (sp = cmdenviron; sp ; sp = sp->next)
 982                 setvareq(sp->text, VEXPORT|VSTACK);
 983         path = pathval();
 984
 985         optind = optreset = 1;
 986         opterr = 0;
 987         while ((ch = getopt(argc, argv, "p")) != -1) {
 988                 switch (ch) {
 989                 case 'p':
 990                         path = stdpath;
 991                         break;
 992                 case '?':
 993                 default:
 994                         error("unknown option: -%c", optopt);
 995                 }
 996         }
 997         argc -= optind;
 998         argv += optind;
 999
1000         if (argc != 0) {
1001                 old = handler;
1002                 handler = &loc;
1003                 if (setjmp(handler->loc) == 0)
1004                         shellexec(argv, environment(), path, 0);
1005                 handler = old;
1006                 if (exception == EXEXEC)
1007                         exit(exerrno);
1008                 exraise(exception);
1009         }
1010
1011         /*
1012          * Do nothing successfully if no command was specified;
1013          * ksh also does this.
1014          */
1015         exit(0);
1016 }
1017
1018
1019 /*
1020  * The return command.
1021  */
1022
1023 int
1024 returncmd(int argc, char **argv)
1025 {
1026         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1027
1028         if (funcnest) {
1029                 evalskip = SKIPFUNC;
1030                 skipcount = 1;
1031         } else {
1032                 /* skip the rest of the file */
1033                 evalskip = SKIPFILE;
1034                 skipcount = 1;
1035         }
1036         return ret;
1037 }
1038
1039
1040 int
1041 falsecmd(int argc __unused, char **argv __unused)
1042 {
1043         return 1;
1044 }
1045
1046
1047 int
1048 truecmd(int argc __unused, char **argv __unused)
1049 {
1050         return 0;
1051 }
1052
1053
1054 int
1055 execcmd(int argc, char **argv)
1056 {
1057         if (argc > 1) {
1058                 struct strlist *sp;
1059
1060                 iflag = 0;              /* exit on error */
1061                 mflag = 0;
1062                 optschanged();
1063                 for (sp = cmdenviron; sp ; sp = sp->next)
1064                         setvareq(sp->text, VEXPORT|VSTACK);
1065                 shellexec(argv + 1, environment(), pathval(), 0);
1066
1067         }
1068         return 0;
1069 }