commands/ash/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  * 4. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #ifndef lint
  34 #if 0
  35 static char sccsid[] = "@(#)eval.c      8.9 (Berkeley) 6/8/95";
  36 #endif
  37 #endif /* not lint */
  38 #include <sys/cdefs.h>
  39 /*
  40 __FBSDID("$FreeBSD: src/bin/sh/eval.c,v 1.42 2004/04/06 20:06:51 markm Exp $");
  41 */
  42
  43 #ifndef NO_PATHS_H
  44 #include <paths.h>
  45 #endif
  46 #include <signal.h>
  47 #include <stdlib.h>
  48 #include <unistd.h>
  49 #include <sys/wait.h> /* For WIFSIGNALED(status) */
  50 #include <errno.h>
  51
  52 /*
  53  * Evaluate a command.
  54  */
  55
  56 #include "shell.h"
  57 #include "nodes.h"
  58 #include "syntax.h"
  59 #include "expand.h"
  60 #include "parser.h"
  61 #include "jobs.h"
  62 #include "eval.h"
  63 #include "builtins.h"
  64 #include "options.h"
  65 #include "exec.h"
  66 #include "redir.h"
  67 #include "input.h"
  68 #include "output.h"
  69 #include "trap.h"
  70 #include "var.h"
  71 #include "memalloc.h"
  72 #include "error.h"
  73 #include "show.h"
  74 #include "mystring.h"
  75 #if !defined(NO_HISTORY)
  76 #include "myhistedit.h"
  77 #endif
  78
  79 #ifndef _PATH_STDPATH
  80 #define _PATH_STDPATH "/usr/bin:/bin:/usr/sbin:/sbin:"
  81 #endif
  82
  83 /* flags in argument to evaltree */
  84 #define EV_EXIT 01              /* exit after evaluating tree */
  85 #define EV_TESTED 02            /* exit status is checked; ignore -e flag */
  86 #define EV_BACKCMD 04           /* command executing within back quotes */
  87
  88 MKINIT int evalskip;            /* set if we are skipping commands */
  89 STATIC int skipcount;           /* number of levels to skip */
  90 MKINIT int loopnest;            /* current loop nesting level */
  91 int funcnest;                   /* depth of function calls */
  92
  93
  94 char *commandname;
  95 struct strlist *cmdenviron;
  96 int exitstatus;                 /* exit status of last command */
  97 int oexitstatus;                /* saved exit status */
  98
  99
 100 STATIC void evalloop(union node *);
 101 STATIC void evalfor(union node *);
 102 STATIC void evalcase(union node *, int);
 103 STATIC void evalsubshell(union node *, int);
 104 STATIC void expredir(union node *);
 105 STATIC void evalpipe(union node *);
 106 STATIC void evalcommand(union node *, int, struct backcmd *);
 107 STATIC void prehash(union node *);
 108
 109
 110 /*
 111  * Called to reset things after an exception.
 112  */
 113
 114 #ifdef mkinit
 115 INCLUDE "eval.h"
 116
 117 RESET {
 118         evalskip = 0;
 119         loopnest = 0;
 120         funcnest = 0;
 121 }
 122
 123 SHELLPROC {
 124         exitstatus = 0;
 125 }
 126 #endif
 127
 128
 129
 130 /*
 131  * The eval command.
 132  */
 133
 134 int
 135 evalcmd(int argc, char **argv)
 136 {
 137         char *p;
 138         char *concat;
 139         char **ap;
 140
 141         if (argc > 1) {
 142                 p = argv[1];
 143                 if (argc > 2) {
 144                         STARTSTACKSTR(concat);
 145                         ap = argv + 2;
 146                         for (;;) {
 147                                 while (*p)
 148                                         STPUTC(*p++, concat);
 149                                 if ((p = *ap++) == NULL)
 150                                         break;
 151                                 STPUTC(' ', concat);
 152                         }
 153                         STPUTC('\0', concat);
 154                         p = grabstackstr(concat);
 155                 }
 156                 evalstring(p);
 157         }
 158         return exitstatus;
 159 }
 160
 161
 162 /*
 163  * Execute a command or commands contained in a string.
 164  */
 165
 166 void
 167 evalstring(char *s)
 168 {
 169         union node *n;
 170         struct stackmark smark;
 171
 172         setstackmark(&smark);
 173         setinputstring(s, 1);
 174         while ((n = parsecmd(0)) != NEOF) {
 175                 evaltree(n, 0);
 176                 popstackmark(&smark);
 177         }
 178         popfile();
 179         popstackmark(&smark);
 180 }
 181
 182
 183
 184 /*
 185  * Evaluate a parse tree.  The value is left in the global variable
 186  * exitstatus.
 187  */
 188
 189 void
 190 evaltree(union node *n, int flags)
 191 {
 192         if (n == NULL) {
 193                 TRACE(("evaltree(NULL) called\n"));
 194                 exitstatus = 0;
 195                 goto out;
 196         }
 197 #if !defined(NO_HISTORY)
 198         displayhist = 1;        /* show history substitutions done with fc */
 199 #endif
 200         TRACE(("evaltree(0x%lx: %d) called\n", (long)n, n->type));
 201         switch (n->type) {
 202         case NSEMI:
 203                 evaltree(n->nbinary.ch1, 0);
 204                 if (evalskip)
 205                         goto out;
 206                 evaltree(n->nbinary.ch2, flags);
 207                 break;
 208         case NAND:
 209                 evaltree(n->nbinary.ch1, EV_TESTED);
 210                 if (evalskip || exitstatus != 0) {
 211                         goto out;
 212                 }
 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                 evaltree(n->nif.test, EV_TESTED);
 235                 if (evalskip)
 236                         goto out;
 237                 if (exitstatus == 0)
 238                         evaltree(n->nif.ifpart, flags);
 239                 else if (n->nif.elsepart)
 240                         evaltree(n->nif.elsepart, flags);
 241                 else
 242                         exitstatus = 0;
 243                 break;
 244         }
 245         case NWHILE:
 246         case NUNTIL:
 247                 evalloop(n);
 248                 break;
 249         case NFOR:
 250                 evalfor(n);
 251                 break;
 252         case NCASE:
 253                 evalcase(n, flags);
 254                 break;
 255         case NDEFUN:
 256                 defun(n->narg.text, n->narg.next);
 257                 exitstatus = 0;
 258                 break;
 259         case NNOT:
 260                 evaltree(n->nnot.com, EV_TESTED);
 261                 exitstatus = !exitstatus;
 262                 break;
 263
 264         case NPIPE:
 265                 evalpipe(n);
 266                 break;
 267         case NCMD:
 268                 evalcommand(n, flags, (struct backcmd *)NULL);
 269                 break;
 270         default:
 271                 out1fmt("Node type = %d\n", n->type);
 272                 flushout(&output);
 273                 break;
 274         }
 275 out:
 276         if (pendingsigs)
 277                 dotrap();
 278         if ((flags & EV_EXIT) || (eflag && exitstatus
 279             && !(flags & EV_TESTED) && (n->type == NCMD ||
 280             n->type == NSUBSHELL)))
 281                 exitshell(exitstatus);
 282 }
 283
 284
 285 STATIC void
 286 evalloop(union node *n)
 287 {
 288         int status;
 289
 290         loopnest++;
 291         status = 0;
 292         for (;;) {
 293                 evaltree(n->nbinary.ch1, EV_TESTED);
 294                 if (evalskip) {
 295 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
 296                                 evalskip = 0;
 297                                 continue;
 298                         }
 299                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 300                                 evalskip = 0;
 301                         break;
 302                 }
 303                 if (n->type == NWHILE) {
 304                         if (exitstatus != 0)
 305                                 break;
 306                 } else {
 307                         if (exitstatus == 0)
 308                                 break;
 309                 }
 310                 evaltree(n->nbinary.ch2, 0);
 311                 status = exitstatus;
 312                 if (evalskip)
 313                         goto skipping;
 314         }
 315         loopnest--;
 316         exitstatus = status;
 317 }
 318
 319
 320
 321 STATIC void
 322 evalfor(union node *n)
 323 {
 324         struct arglist arglist;
 325         union node *argp;
 326         struct strlist *sp;
 327         struct stackmark smark;
 328
 329         setstackmark(&smark);
 330         arglist.lastp = &arglist.list;
 331         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 332                 oexitstatus = exitstatus;
 333                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 334                 if (evalskip)
 335                         goto out;
 336         }
 337         *arglist.lastp = NULL;
 338
 339         exitstatus = 0;
 340         loopnest++;
 341         for (sp = arglist.list ; sp ; sp = sp->next) {
 342                 setvar(n->nfor.var, sp->text, 0);
 343                 evaltree(n->nfor.body, 0);
 344                 if (evalskip) {
 345                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 346                                 evalskip = 0;
 347                                 continue;
 348                         }
 349                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 350                                 evalskip = 0;
 351                         break;
 352                 }
 353         }
 354         loopnest--;
 355 out:
 356         popstackmark(&smark);
 357 }
 358
 359
 360
 361 STATIC void
 362 evalcase(union node *n, int flags)
 363 {
 364         union node *cp;
 365         union node *patp;
 366         struct arglist arglist;
 367         struct stackmark smark;
 368
 369         setstackmark(&smark);
 370         arglist.lastp = &arglist.list;
 371         oexitstatus = exitstatus;
 372         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 373         for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
 374                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 375                         if (casematch(patp, arglist.list->text)) {
 376                                 if (evalskip == 0) {
 377                                         evaltree(cp->nclist.body, flags);
 378                                 }
 379                                 goto out;
 380                         }
 381                 }
 382         }
 383 out:
 384         popstackmark(&smark);
 385 }
 386
 387
 388
 389 /*
 390  * Kick off a subshell to evaluate a tree.
 391  */
 392
 393 STATIC void
 394 evalsubshell(union node *n, int flags)
 395 {
 396         struct job *jp;
 397         int backgnd = (n->type == NBACKGND);
 398
 399         expredir(n->nredir.redirect);
 400         jp = makejob(n, 1);
 401         if (forkshell(jp, n, backgnd) == 0) {
 402                 if (backgnd)
 403                         flags &=~ EV_TESTED;
 404                 redirect(n->nredir.redirect, 0);
 405                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 406         }
 407         if (! backgnd) {
 408                 INTOFF;
 409                 exitstatus = waitforjob(jp, (int *)NULL);
 410                 INTON;
 411         }
 412 }
 413
 414
 415
 416 /*
 417  * Compute the names of the files in a redirection list.
 418  */
 419
 420 STATIC void
 421 expredir(union node *n)
 422 {
 423         union node *redir;
 424
 425         for (redir = n ; redir ; redir = redir->nfile.next) {
 426                 struct arglist fn;
 427                 fn.lastp = &fn.list;
 428                 oexitstatus = exitstatus;
 429                 switch (redir->type) {
 430                 case NFROM:
 431                 case NTO:
 432                 case NFROMTO:
 433                 case NAPPEND:
 434                 case NCLOBBER:
 435                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 436                         redir->nfile.expfname = fn.list->text;
 437                         break;
 438                 case NFROMFD:
 439                 case NTOFD:
 440                         if (redir->ndup.vname) {
 441                                 expandarg(redir->ndup.vname, &fn, EXP_FULL | EXP_TILDE);
 442                                 fixredir(redir, fn.list->text, 1);
 443                         }
 444                         break;
 445                 }
 446         }
 447 }
 448
 449
 450
 451 /*
 452  * Evaluate a pipeline.  All the processes in the pipeline are children
 453  * of the process creating the pipeline.  (This differs from some versions
 454  * of the shell, which make the last process in a pipeline the parent
 455  * of all the rest.)
 456  */
 457
 458 STATIC void
 459 evalpipe(union node *n)
 460 {
 461         struct job *jp;
 462         struct nodelist *lp;
 463         int pipelen;
 464         int prevfd;
 465         int pip[2];
 466
 467         TRACE(("evalpipe(0x%lx) called\n", (long)n));
 468         pipelen = 0;
 469         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
 470                 pipelen++;
 471         INTOFF;
 472         jp = makejob(n, pipelen);
 473         prevfd = -1;
 474         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
 475                 prehash(lp->n);
 476                 pip[1] = -1;
 477                 if (lp->next) {
 478                         if (pipe(pip) < 0) {
 479                                 close(prevfd);
 480                                 error("Pipe call failed: %s", strerror(errno));
 481                         }
 482                 }
 483                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
 484                         INTON;
 485                         if (prevfd > 0) {
 486                                 dup2(prevfd, 0);
 487                                 close(prevfd);
 488                         }
 489                         if (pip[1] >= 0) {
 490                                 if (!(prevfd >= 0 && pip[0] == 0))
 491                                         close(pip[0]);
 492                                 if (pip[1] != 1) {
 493                                         dup2(pip[1], 1);
 494                                         close(pip[1]);
 495                                 }
 496                         }
 497                         evaltree(lp->n, EV_EXIT);
 498                 }
 499                 if (prevfd >= 0)
 500                         close(prevfd);
 501                 prevfd = pip[0];
 502                 close(pip[1]);
 503         }
 504         INTON;
 505         if (n->npipe.backgnd == 0) {
 506                 INTOFF;
 507                 exitstatus = waitforjob(jp, (int *)NULL);
 508                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 509                 INTON;
 510         }
 511 }
 512
 513
 514
 515 /*
 516  * Execute a command inside back quotes.  If it's a builtin command, we
 517  * want to save its output in a block obtained from malloc.  Otherwise
 518  * we fork off a subprocess and get the output of the command via a pipe.
 519  * Should be called with interrupts off.
 520  */
 521
 522 void
 523 evalbackcmd(union node *n, struct backcmd *result)
 524 {
 525         int pip[2];
 526         struct job *jp;
 527         struct stackmark smark;         /* unnecessary */
 528
 529         setstackmark(&smark);
 530         result->fd = -1;
 531         result->buf = NULL;
 532         result->nleft = 0;
 533         result->jp = NULL;
 534         if (n == NULL) {
 535                 exitstatus = 0;
 536                 goto out;
 537         }
 538         if (n->type == NCMD) {
 539                 exitstatus = oexitstatus;
 540                 evalcommand(n, EV_BACKCMD, result);
 541         } else {
 542                 exitstatus = 0;
 543                 if (pipe(pip) < 0)
 544                         error("Pipe call failed: %s", strerror(errno));
 545                 jp = makejob(n, 1);
 546                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 547                         FORCEINTON;
 548                         close(pip[0]);
 549                         if (pip[1] != 1) {
 550                                 dup2(pip[1], 1);
 551                                 close(pip[1]);
 552                         }
 553                         evaltree(n, EV_EXIT);
 554                 }
 555                 close(pip[1]);
 556                 result->fd = pip[0];
 557                 result->jp = jp;
 558         }
 559 out:
 560         popstackmark(&smark);
 561         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 562                 result->fd, result->buf, result->nleft, result->jp));
 563 }
 564
 565
 566
 567 /*
 568  * Execute a simple command.
 569  */
 570
 571 STATIC void
 572 evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
 573 {
 574         struct stackmark smark;
 575         union node *argp;
 576         struct arglist arglist;
 577         struct arglist varlist;
 578         char **argv;
 579         int argc;
 580         char **envp;
 581         int varflag;
 582         struct strlist *sp;
 583         int mode;
 584         int pip[2];
 585         struct cmdentry cmdentry;
 586         struct job *jp;
 587         struct jmploc jmploc;
 588         struct jmploc *volatile savehandler;
 589         char *volatile savecmdname;
 590         volatile struct shparam saveparam;
 591         struct localvar *volatile savelocalvars;
 592         volatile int e;
 593         char *lastarg;
 594         int realstatus;
 595         int do_clearcmdentry;
 596 #if __GNUC__
 597         /* Avoid longjmp clobbering */
 598         (void) &argv;
 599         (void) &argc;
 600         (void) &lastarg;
 601         (void) &flags;
 602         (void) &do_clearcmdentry;
 603 #endif
 604
 605         /* First expand the arguments. */
 606         TRACE(("evalcommand(0x%lx, %d) called\n", (long)cmd, flags));
 607         setstackmark(&smark);
 608         arglist.lastp = &arglist.list;
 609         varlist.lastp = &varlist.list;
 610         varflag = 1;
 611         do_clearcmdentry = 0;
 612         oexitstatus = exitstatus;
 613         exitstatus = 0;
 614         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 615                 char *p = argp->narg.text;
 616                 if (varflag && is_name(*p)) {
 617                         do {
 618                                 p++;
 619                         } while (is_in_name(*p));
 620                         if (*p == '=') {
 621                                 expandarg(argp, &varlist, EXP_VARTILDE);
 622                                 continue;
 623                         }
 624                 }
 625                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 626                 varflag = 0;
 627         }
 628         *arglist.lastp = NULL;
 629         *varlist.lastp = NULL;
 630         expredir(cmd->ncmd.redirect);
 631         argc = 0;
 632         for (sp = arglist.list ; sp ; sp = sp->next)
 633                 argc++;
 634         argv = stalloc(sizeof (char *) * (argc + 1));
 635
 636         for (sp = arglist.list ; sp ; sp = sp->next) {
 637                 TRACE(("evalcommand arg: %s\n", sp->text));
 638                 *argv++ = sp->text;
 639         }
 640         *argv = NULL;
 641         lastarg = NULL;
 642         if (iflag && funcnest == 0 && argc > 0)
 643                 lastarg = argv[-1];
 644         argv -= argc;
 645
 646         /* Print the command if xflag is set. */
 647         if (xflag) {
 648                 outc('+', &errout);
 649                 for (sp = varlist.list ; sp ; sp = sp->next) {
 650                         outc(' ', &errout);
 651                         out2str(sp->text);
 652                 }
 653                 for (sp = arglist.list ; sp ; sp = sp->next) {
 654                         outc(' ', &errout);
 655                         out2str(sp->text);
 656                 }
 657                 outc('\n', &errout);
 658                 flushout(&errout);
 659         }
 660
 661         /* Now locate the command. */
 662         if (argc == 0) {
 663                 cmdentry.cmdtype = CMDBUILTIN;
 664                 cmdentry.u.index = BLTINCMD;
 665         } else {
 666                 static const char PATH[] = "PATH=";
 667                 char *path = pathval();
 668
 669                 /*
 670                  * Modify the command lookup path, if a PATH= assignment
 671                  * is present
 672                  */
 673                 for (sp = varlist.list ; sp ; sp = sp->next)
 674                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 675                                 path = sp->text + sizeof(PATH) - 1;
 676                                 /*
 677                                  * On `PATH=... command`, we need to make
 678                                  * sure that the command isn't using the
 679                                  * non-updated hash table of the outer PATH
 680                                  * setting and we need to make sure that
 681                                  * the hash table isn't filled with items
 682                                  * from the temporary setting.
 683                                  *
 684                                  * It would be better to forbit using and
 685                                  * updating the table while this command
 686                                  * runs, by the command finding mechanism
 687                                  * is heavily integrated with hash handling,
 688                                  * so we just delete the hash before and after
 689                                  * the command runs. Partly deleting like
 690                                  * changepatch() does doesn't seem worth the
 691                                  * bookinging effort, since most such runs add
 692                                  * directories in front of the new PATH.
 693                                  */
 694                                 clearcmdentry(0);
 695                                 do_clearcmdentry = 1;
 696                         }
 697
 698                 find_command(argv[0], &cmdentry, 1, path);
 699                 if (cmdentry.cmdtype == CMDUNKNOWN) {   /* command not found */
 700                         exitstatus = 127;
 701                         flushout(&errout);
 702                         return;
 703                 }
 704                 /* implement the bltin builtin here */
 705                 if (cmdentry.cmdtype == CMDBUILTIN && cmdentry.u.index == BLTINCMD) {
 706                         for (;;) {
 707                                 argv++;
 708                                 if (--argc == 0)
 709                                         break;
 710                                 if ((cmdentry.u.index = find_builtin(*argv)) < 0) {
 711                                         outfmt(&errout, "%s: not found\n", *argv);
 712                                         exitstatus = 127;
 713                                         flushout(&errout);
 714                                         return;
 715                                 }
 716                                 if (cmdentry.u.index != BLTINCMD)
 717                                         break;
 718                         }
 719                 }
 720         }
 721
 722         /* Fork off a child process if necessary. */
 723         if (cmd->ncmd.backgnd
 724          || (cmdentry.cmdtype == CMDNORMAL
 725             && ((flags & EV_EXIT) == 0 || Tflag))
 726          || ((flags & EV_BACKCMD) != 0
 727             && (cmdentry.cmdtype != CMDBUILTIN
 728                  || cmdentry.u.index == CDCMD
 729                  || cmdentry.u.index == DOTCMD
 730                  || cmdentry.u.index == EVALCMD))
 731          || (cmdentry.cmdtype == CMDBUILTIN &&
 732             cmdentry.u.index == COMMANDCMD)) {
 733                 jp = makejob(cmd, 1);
 734                 mode = cmd->ncmd.backgnd;
 735                 if (flags & EV_BACKCMD) {
 736                         mode = FORK_NOJOB;
 737                         if (pipe(pip) < 0)
 738                                 error("Pipe call failed: %s", strerror(errno));
 739                 }
 740                 if (forkshell(jp, cmd, mode) != 0)
 741                         goto parent;    /* at end of routine */
 742                 if (flags & EV_BACKCMD) {
 743                         FORCEINTON;
 744                         close(pip[0]);
 745                         if (pip[1] != 1) {
 746                                 dup2(pip[1], 1);
 747                                 close(pip[1]);
 748                         }
 749                 }
 750                 flags |= EV_EXIT;
 751         }
 752
 753         /* This is the child process if a fork occurred. */
 754         /* Execute the command. */
 755         if (cmdentry.cmdtype == CMDFUNCTION) {
 756 #if DEBUG
 757                 trputs("Shell function:  ");  trargs(argv);
 758 #endif
 759                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
 760                 saveparam = shellparam;
 761                 shellparam.malloc = 0;
 762                 shellparam.reset = 1;
 763                 shellparam.nparam = argc - 1;
 764                 shellparam.p = argv + 1;
 765                 shellparam.optnext = NULL;
 766                 INTOFF;
 767                 savelocalvars = localvars;
 768                 localvars = NULL;
 769                 INTON;
 770                 if (setjmp(jmploc.loc)) {
 771                         if (exception == EXSHELLPROC)
 772                                 freeparam((struct shparam *)&saveparam);
 773                         else {
 774                                 freeparam(&shellparam);
 775                                 shellparam = saveparam;
 776                         }
 777                         poplocalvars();
 778                         localvars = savelocalvars;
 779                         handler = savehandler;
 780                         longjmp(handler->loc, 1);
 781                 }
 782                 savehandler = handler;
 783                 handler = &jmploc;
 784                 for (sp = varlist.list ; sp ; sp = sp->next)
 785                         mklocal(sp->text);
 786                 funcnest++;
 787                 if (flags & EV_TESTED)
 788                         evaltree(cmdentry.u.func, EV_TESTED);
 789                 else
 790                         evaltree(cmdentry.u.func, 0);
 791                 funcnest--;
 792                 INTOFF;
 793                 poplocalvars();
 794                 localvars = savelocalvars;
 795                 freeparam(&shellparam);
 796                 shellparam = saveparam;
 797                 handler = savehandler;
 798                 popredir();
 799                 INTON;
 800                 if (evalskip == SKIPFUNC) {
 801                         evalskip = 0;
 802                         skipcount = 0;
 803                 }
 804                 if (flags & EV_EXIT)
 805                         exitshell(exitstatus);
 806         } else if (cmdentry.cmdtype == CMDBUILTIN) {
 807 #if DEBUG
 808                 trputs("builtin command:  ");  trargs(argv);
 809 #endif
 810                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
 811                 if (flags == EV_BACKCMD) {
 812                         memout.nleft = 0;
 813                         memout.nextc = memout.buf;
 814                         memout.bufsize = 64;
 815                         mode |= REDIR_BACKQ;
 816                 }
 817                 redirect(cmd->ncmd.redirect, mode);
 818                 savecmdname = commandname;
 819                 cmdenviron = varlist.list;
 820                 e = -1;
 821                 if (setjmp(jmploc.loc)) {
 822                         e = exception;
 823                         exitstatus = (e == EXINT)? SIGINT+128 : 2;
 824                         goto cmddone;
 825                 }
 826                 savehandler = handler;
 827                 handler = &jmploc;
 828                 commandname = argv[0];
 829                 argptr = argv + 1;
 830                 optptr = NULL;                  /* initialize nextopt */
 831                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
 832                 flushall();
 833 cmddone:
 834                 cmdenviron = NULL;
 835                 out1 = &output;
 836                 out2 = &errout;
 837                 freestdout();
 838                 if (e != EXSHELLPROC) {
 839                         commandname = savecmdname;
 840                         if (flags & EV_EXIT) {
 841                                 exitshell(exitstatus);
 842                         }
 843                 }
 844                 handler = savehandler;
 845                 if (e != -1) {
 846                         if ((e != EXERROR && e != EXEXEC)
 847                            || cmdentry.u.index == BLTINCMD
 848                            || cmdentry.u.index == DOTCMD
 849                            || cmdentry.u.index == EVALCMD
 850 #ifndef NO_HISTORY
 851                            || cmdentry.u.index == HISTCMD
 852 #endif
 853                            || cmdentry.u.index == EXECCMD
 854                            || cmdentry.u.index == COMMANDCMD)
 855                                 exraise(e);
 856                         FORCEINTON;
 857                 }
 858                 if (cmdentry.u.index != EXECCMD)
 859                         popredir();
 860                 if (flags == EV_BACKCMD) {
 861                         backcmd->buf = memout.buf;
 862                         backcmd->nleft = memout.nextc - memout.buf;
 863                         memout.buf = NULL;
 864                 }
 865         } else {
 866 #if DEBUG
 867                 trputs("normal command:  ");  trargs(argv);
 868 #endif
 869                 clearredir();
 870                 redirect(cmd->ncmd.redirect, 0);
 871                 for (sp = varlist.list ; sp ; sp = sp->next)
 872                         setvareq(sp->text, VEXPORT|VSTACK);
 873                 envp = environment();
 874                 shellexec(argv, envp, pathval(), cmdentry.u.index);
 875                 /*NOTREACHED*/
 876         }
 877         goto out;
 878
 879 parent: /* parent process gets here (if we forked) */
 880         if (mode == 0) {        /* argument to fork */
 881                 INTOFF;
 882                 exitstatus = waitforjob(jp, &realstatus);
 883                 INTON;
 884                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
 885                         evalskip = SKIPBREAK;
 886                         skipcount = loopnest;
 887                 }
 888         } else if (mode == 2) {
 889                 backcmd->fd = pip[0];
 890                 close(pip[1]);
 891                 backcmd->jp = jp;
 892         }
 893
 894 out:
 895         if (lastarg)
 896                 setvar("_", lastarg, 0);
 897         if (do_clearcmdentry)
 898                 clearcmdentry(0);
 899         popstackmark(&smark);
 900 }
 901
 902
 903
 904 /*
 905  * Search for a command.  This is called before we fork so that the
 906  * location of the command will be available in the parent as well as
 907  * the child.  The check for "goodname" is an overly conservative
 908  * check that the name will not be subject to expansion.
 909  */
 910
 911 STATIC void
 912 prehash(union node *n)
 913 {
 914         struct cmdentry entry;
 915
 916         if (n->type == NCMD && n->ncmd.args)
 917                 if (goodname(n->ncmd.args->narg.text))
 918                         find_command(n->ncmd.args->narg.text, &entry, 0,
 919                                      pathval());
 920 }
 921
 922
 923
 924 /*
 925  * Builtin commands.  Builtin commands whose functions are closely
 926  * tied to evaluation are implemented here.
 927  */
 928
 929 /*
 930  * No command given, or a bltin command with no arguments.  Set the
 931  * specified variables.
 932  */
 933
 934 int
 935 bltincmd(int argc __unused, char **argv __unused)
 936 {
 937         listsetvar(cmdenviron);
 938         /*
 939          * Preserve exitstatus of a previous possible redirection
 940          * as POSIX mandates
 941          */
 942         return exitstatus;
 943 }
 944
 945
 946 /*
 947  * Handle break and continue commands.  Break, continue, and return are
 948  * all handled by setting the evalskip flag.  The evaluation routines
 949  * above all check this flag, and if it is set they start skipping
 950  * commands rather than executing them.  The variable skipcount is
 951  * the number of loops to break/continue, or the number of function
 952  * levels to return.  (The latter is always 1.)  It should probably
 953  * be an error to break out of more loops than exist, but it isn't
 954  * in the standard shell so we don't make it one here.
 955  */
 956
 957 int
 958 breakcmd(int argc, char **argv)
 959 {
 960         int n = argc > 1 ? number(argv[1]) : 1;
 961
 962         if (n > loopnest)
 963                 n = loopnest;
 964         if (n > 0) {
 965                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
 966                 skipcount = n;
 967         }
 968         return 0;
 969 }
 970
 971 /*
 972  * The `command' command.
 973  */
 974 int
 975 commandcmd(int argc, char **argv)
 976 {
 977         static char stdpath[] = _PATH_STDPATH;
 978         struct jmploc loc, *old;
 979         struct strlist *sp;
 980         char *path;
 981         int ch;
 982
 983         for (sp = cmdenviron; sp ; sp = sp->next)
 984                 setvareq(sp->text, VEXPORT|VSTACK);
 985         path = pathval();
 986
 987         optind = optreset = 1;
 988         opterr = 0;
 989         while ((ch = getopt(argc, argv, "p")) != -1) {
 990                 switch (ch) {
 991                 case 'p':
 992                         path = stdpath;
 993                         break;
 994                 case '?':
 995                 default:
 996                         error("unknown option: -%c", optopt);
 997                 }
 998         }
 999         argc -= optind;
1000         argv += optind;
1001
1002         if (argc != 0) {
1003                 old = handler;
1004                 handler = &loc;
1005                 if (setjmp(handler->loc) == 0)
1006                         shellexec(argv, environment(), path, 0);
1007                 handler = old;
1008                 if (exception == EXEXEC)
1009                         exit(exerrno);
1010                 exraise(exception);
1011         }
1012
1013         /*
1014          * Do nothing successfully if no command was specified;
1015          * ksh also does this.
1016          */
1017         exit(0);
1018 }
1019
1020
1021 /*
1022  * The return command.
1023  */
1024
1025 int
1026 returncmd(int argc, char **argv)
1027 {
1028         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1029
1030         if (funcnest) {
1031                 evalskip = SKIPFUNC;
1032                 skipcount = 1;
1033         } else {
1034                 /* skip the rest of the file */
1035                 evalskip = SKIPFILE;
1036                 skipcount = 1;
1037         }
1038         return ret;
1039 }
1040
1041
1042 int
1043 falsecmd(int argc __unused, char **argv __unused)
1044 {
1045         return 1;
1046 }
1047
1048
1049 int
1050 truecmd(int argc __unused, char **argv __unused)
1051 {
1052         return 0;
1053 }
1054
1055
1056 int
1057 execcmd(int argc, char **argv)
1058 {
1059         if (argc > 1) {
1060                 struct strlist *sp;
1061
1062                 iflag = 0;              /* exit on error */
1063                 mflag = 0;
1064                 optschanged();
1065                 for (sp = cmdenviron; sp ; sp = sp->next)
1066                         setvareq(sp->text, VEXPORT|VSTACK);
1067                 shellexec(argv + 1, environment(), pathval(), 0);
1068
1069         }
1070         return 0;
1071 }
1072
1073 /*
1074  * $PchId: eval.c,v 1.7 2006/04/10 14:46:14 philip Exp $
1075  */