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
  37 #ifndef lint
  38 #if 0
  39 static char sccsid[] = "@(#)eval.c      8.9 (Berkeley) 6/8/95";
  40 #endif
  41 #endif /* not lint */
  42 #include <sys/cdefs.h>
  43 __FBSDID("$FreeBSD: src/bin/sh/eval.c,v 1.27.2.5 2002/08/27 01:36:28 tjr Exp $");
  44
  45 #include <paths.h>
  46 #include <signal.h>
  47 #include <unistd.h>
  48 #include <sys/wait.h> /* For WIFSIGNALED(status) */
  49 #include <errno.h>
  50
  51 /*
  52  * Evaluate a command.
  53  */
  54
  55 #include "shell.h"
  56 #include "nodes.h"
  57 #include "syntax.h"
  58 #include "expand.h"
  59 #include "parser.h"
  60 #include "jobs.h"
  61 #include "eval.h"
  62 #include "builtins.h"
  63 #include "options.h"
  64 #include "exec.h"
  65 #include "redir.h"
  66 #include "input.h"
  67 #include "output.h"
  68 #include "trap.h"
  69 #include "var.h"
  70 #include "memalloc.h"
  71 #include "error.h"
  72 #include "show.h"
  73 #include "mystring.h"
  74 #ifndef NO_HISTORY
  75 #include "myhistedit.h"
  76 #endif
  77
  78
  79 /* flags in argument to evaltree */
  80 #define EV_EXIT 01              /* exit after evaluating tree */
  81 #define EV_TESTED 02            /* exit status is checked; ignore -e flag */
  82 #define EV_BACKCMD 04           /* command executing within back quotes */
  83
  84 MKINIT int evalskip;            /* set if we are skipping commands */
  85 STATIC int skipcount;           /* number of levels to skip */
  86 MKINIT int loopnest;            /* current loop nesting level */
  87 int funcnest;                   /* depth of function calls */
  88
  89
  90 char *commandname;
  91 struct strlist *cmdenviron;
  92 int exitstatus;                 /* exit status of last command */
  93 int oexitstatus;                /* saved exit status */
  94
  95
  96 STATIC void evalloop(union node *);
  97 STATIC void evalfor(union node *);
  98 STATIC void evalcase(union node *, int);
  99 STATIC void evalsubshell(union node *, int);
 100 STATIC void expredir(union node *);
 101 STATIC void evalpipe(union node *);
 102 STATIC void evalcommand(union node *, int, struct backcmd *);
 103 STATIC void prehash(union node *);
 104
 105
 106 /*
 107  * Called to reset things after an exception.
 108  */
 109
 110 #ifdef mkinit
 111 INCLUDE "eval.h"
 112
 113 RESET {
 114         evalskip = 0;
 115         loopnest = 0;
 116         funcnest = 0;
 117 }
 118
 119 SHELLPROC {
 120         exitstatus = 0;
 121 }
 122 #endif
 123
 124
 125
 126 /*
 127  * The eval command.
 128  */
 129
 130 int
 131 evalcmd(int argc, char **argv)
 132 {
 133         char *p;
 134         char *concat;
 135         char **ap;
 136
 137         if (argc > 1) {
 138                 p = argv[1];
 139                 if (argc > 2) {
 140                         STARTSTACKSTR(concat);
 141                         ap = argv + 2;
 142                         for (;;) {
 143                                 while (*p)
 144                                         STPUTC(*p++, concat);
 145                                 if ((p = *ap++) == NULL)
 146                                         break;
 147                                 STPUTC(' ', concat);
 148                         }
 149                         STPUTC('\0', concat);
 150                         p = grabstackstr(concat);
 151                 }
 152                 evalstring(p);
 153         }
 154         return exitstatus;
 155 }
 156
 157
 158 /*
 159  * Execute a command or commands contained in a string.
 160  */
 161
 162 void
 163 evalstring(char *s)
 164 {
 165         union node *n;
 166         struct stackmark smark;
 167
 168         setstackmark(&smark);
 169         setinputstring(s, 1);
 170         while ((n = parsecmd(0)) != NEOF) {
 171                 evaltree(n, 0);
 172                 popstackmark(&smark);
 173         }
 174         popfile();
 175         popstackmark(&smark);
 176 }
 177
 178
 179
 180 /*
 181  * Evaluate a parse tree.  The value is left in the global variable
 182  * exitstatus.
 183  */
 184
 185 void
 186 evaltree(union node *n, int flags)
 187 {
 188         if (n == NULL) {
 189                 TRACE(("evaltree(NULL) called\n"));
 190                 exitstatus = 0;
 191                 goto out;
 192         }
 193 #ifndef NO_HISTORY
 194         displayhist = 1;        /* show history substitutions done with fc */
 195 #endif
 196         TRACE(("evaltree(0x%lx: %d) called\n", (long)n, n->type));
 197         switch (n->type) {
 198         case NSEMI:
 199                 evaltree(n->nbinary.ch1, 0);
 200                 if (evalskip)
 201                         goto out;
 202                 evaltree(n->nbinary.ch2, flags);
 203                 break;
 204         case NAND:
 205                 evaltree(n->nbinary.ch1, EV_TESTED);
 206                 if (evalskip || exitstatus != 0) {
 207                         flags |= EV_TESTED;
 208                         goto out;
 209                 }
 210                 evaltree(n->nbinary.ch2, flags);
 211                 break;
 212         case NOR:
 213                 evaltree(n->nbinary.ch1, EV_TESTED);
 214                 if (evalskip || exitstatus == 0)
 215                         goto out;
 216                 evaltree(n->nbinary.ch2, flags);
 217                 break;
 218         case NREDIR:
 219                 expredir(n->nredir.redirect);
 220                 redirect(n->nredir.redirect, REDIR_PUSH);
 221                 evaltree(n->nredir.n, flags);
 222                 popredir();
 223                 break;
 224         case NSUBSHELL:
 225                 evalsubshell(n, flags);
 226                 break;
 227         case NBACKGND:
 228                 evalsubshell(n, flags);
 229                 break;
 230         case NIF: {
 231                 evaltree(n->nif.test, EV_TESTED);
 232                 if (evalskip)
 233                         goto out;
 234                 if (exitstatus == 0)
 235                         evaltree(n->nif.ifpart, flags);
 236                 else if (n->nif.elsepart)
 237                         evaltree(n->nif.elsepart, flags);
 238                 else
 239                         exitstatus = 0;
 240                 break;
 241         }
 242         case NWHILE:
 243         case NUNTIL:
 244                 evalloop(n);
 245                 break;
 246         case NFOR:
 247                 evalfor(n);
 248                 /*
 249                  * The 'for' command does not set exitstatus, so the value
 250                  * now in exitstatus is from the last command executed in
 251                  * the 'for' loop.  That exit value had been tested (wrt
 252                  * 'sh -e' checking) while processing that command, and
 253                  * it should not be re-tested here.
 254                  */
 255                 flags |= EV_TESTED;
 256                 break;
 257         case NCASE:
 258                 evalcase(n, flags);
 259                 /*
 260                  * The 'case' command does not set exitstatus, so the value
 261                  * now in exitstatus is from the last command executed in
 262                  * the 'case' block.  That exit value had been tested (wrt
 263                  * 'sh -e' checking) while processing that command, and
 264                  * it should not be re-tested here.
 265                  */
 266                 flags |= EV_TESTED;
 267                 break;
 268         case NDEFUN:
 269                 defun(n->narg.text, n->narg.next);
 270                 exitstatus = 0;
 271                 break;
 272         case NNOT:
 273                 evaltree(n->nnot.com, EV_TESTED);
 274                 exitstatus = !exitstatus;
 275                 break;
 276
 277         case NPIPE:
 278                 evalpipe(n);
 279                 break;
 280         case NCMD:
 281                 evalcommand(n, flags, (struct backcmd *)NULL);
 282                 break;
 283         default:
 284                 out1fmt("Node type = %d\n", n->type);
 285                 flushout(&output);
 286                 break;
 287         }
 288 out:
 289         if (pendingsigs)
 290                 dotrap();
 291         /*
 292          * XXX - Like "!(n->type == NSEMI)", more types will probably
 293          * need to be excluded from this test. It's probably better
 294          * to set or unset EV_TESTED in the loop above than to bloat
 295          * the conditional here.
 296          */
 297         if ((flags & EV_EXIT) || (eflag && exitstatus
 298             && !(flags & EV_TESTED) && !(n->type == NSEMI)))
 299                 exitshell(exitstatus);
 300 }
 301
 302
 303 STATIC void
 304 evalloop(union node *n)
 305 {
 306         int status;
 307
 308         loopnest++;
 309         status = 0;
 310         for (;;) {
 311                 evaltree(n->nbinary.ch1, EV_TESTED);
 312                 if (evalskip) {
 313 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
 314                                 evalskip = 0;
 315                                 continue;
 316                         }
 317                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 318                                 evalskip = 0;
 319                         break;
 320                 }
 321                 if (n->type == NWHILE) {
 322                         if (exitstatus != 0)
 323                                 break;
 324                 } else {
 325                         if (exitstatus == 0)
 326                                 break;
 327                 }
 328                 evaltree(n->nbinary.ch2, 0);
 329                 status = exitstatus;
 330                 if (evalskip)
 331                         goto skipping;
 332         }
 333         loopnest--;
 334         exitstatus = status;
 335 }
 336
 337
 338
 339 STATIC void
 340 evalfor(union node *n)
 341 {
 342         struct arglist arglist;
 343         union node *argp;
 344         struct strlist *sp;
 345         struct stackmark smark;
 346
 347         setstackmark(&smark);
 348         arglist.lastp = &arglist.list;
 349         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 350                 oexitstatus = exitstatus;
 351                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 352                 if (evalskip)
 353                         goto out;
 354         }
 355         *arglist.lastp = NULL;
 356
 357         exitstatus = 0;
 358         loopnest++;
 359         for (sp = arglist.list ; sp ; sp = sp->next) {
 360                 setvar(n->nfor.var, sp->text, 0);
 361                 evaltree(n->nfor.body, 0);
 362                 if (evalskip) {
 363                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 364                                 evalskip = 0;
 365                                 continue;
 366                         }
 367                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 368                                 evalskip = 0;
 369                         break;
 370                 }
 371         }
 372         loopnest--;
 373 out:
 374         popstackmark(&smark);
 375 }
 376
 377
 378
 379 STATIC void
 380 evalcase(union node *n, int flags)
 381 {
 382         union node *cp;
 383         union node *patp;
 384         struct arglist arglist;
 385         struct stackmark smark;
 386
 387         setstackmark(&smark);
 388         arglist.lastp = &arglist.list;
 389         oexitstatus = exitstatus;
 390         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 391         for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
 392                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 393                         if (casematch(patp, arglist.list->text)) {
 394                                 if (evalskip == 0) {
 395                                         evaltree(cp->nclist.body, flags);
 396                                 }
 397                                 goto out;
 398                         }
 399                 }
 400         }
 401 out:
 402         popstackmark(&smark);
 403 }
 404
 405
 406
 407 /*
 408  * Kick off a subshell to evaluate a tree.
 409  */
 410
 411 STATIC void
 412 evalsubshell(union node *n, int flags)
 413 {
 414         struct job *jp;
 415         int backgnd = (n->type == NBACKGND);
 416
 417         expredir(n->nredir.redirect);
 418         jp = makejob(n, 1);
 419         if (forkshell(jp, n, backgnd) == 0) {
 420                 if (backgnd)
 421                         flags &=~ EV_TESTED;
 422                 redirect(n->nredir.redirect, 0);
 423                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 424         }
 425         if (! backgnd) {
 426                 INTOFF;
 427                 exitstatus = waitforjob(jp, (int *)NULL);
 428                 INTON;
 429         }
 430 }
 431
 432
 433
 434 /*
 435  * Compute the names of the files in a redirection list.
 436  */
 437
 438 STATIC void
 439 expredir(union node *n)
 440 {
 441         union node *redir;
 442
 443         for (redir = n ; redir ; redir = redir->nfile.next) {
 444                 struct arglist fn;
 445                 fn.lastp = &fn.list;
 446                 oexitstatus = exitstatus;
 447                 switch (redir->type) {
 448                 case NFROM:
 449                 case NTO:
 450                 case NFROMTO:
 451                 case NAPPEND:
 452                 case NCLOBBER:
 453                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 454                         redir->nfile.expfname = fn.list->text;
 455                         break;
 456                 case NFROMFD:
 457                 case NTOFD:
 458                         if (redir->ndup.vname) {
 459                                 expandarg(redir->ndup.vname, &fn, EXP_FULL | EXP_TILDE);
 460                                 fixredir(redir, fn.list->text, 1);
 461                         }
 462                         break;
 463                 }
 464         }
 465 }
 466
 467
 468
 469 /*
 470  * Evaluate a pipeline.  All the processes in the pipeline are children
 471  * of the process creating the pipeline.  (This differs from some versions
 472  * of the shell, which make the last process in a pipeline the parent
 473  * of all the rest.)
 474  */
 475
 476 STATIC void
 477 evalpipe(union node *n)
 478 {
 479         struct job *jp;
 480         struct nodelist *lp;
 481         int pipelen;
 482         int prevfd;
 483         int pip[2];
 484
 485         TRACE(("evalpipe(0x%lx) called\n", (long)n));
 486         pipelen = 0;
 487         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
 488                 pipelen++;
 489         INTOFF;
 490         jp = makejob(n, pipelen);
 491         prevfd = -1;
 492         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
 493                 prehash(lp->n);
 494                 pip[1] = -1;
 495                 if (lp->next) {
 496                         if (pipe(pip) < 0) {
 497                                 close(prevfd);
 498                                 error("Pipe call failed: %s", strerror(errno));
 499                         }
 500                 }
 501                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
 502                         INTON;
 503                         if (prevfd > 0) {
 504                                 close(0);
 505                                 copyfd(prevfd, 0);
 506                                 close(prevfd);
 507                         }
 508                         if (pip[1] >= 0) {
 509                                 if (!(prevfd >= 0 && pip[0] == 0))
 510                                         close(pip[0]);
 511                                 if (pip[1] != 1) {
 512                                         close(1);
 513                                         copyfd(pip[1], 1);
 514                                         close(pip[1]);
 515                                 }
 516                         }
 517                         evaltree(lp->n, EV_EXIT);
 518                 }
 519                 if (prevfd >= 0)
 520                         close(prevfd);
 521                 prevfd = pip[0];
 522                 close(pip[1]);
 523         }
 524         INTON;
 525         if (n->npipe.backgnd == 0) {
 526                 INTOFF;
 527                 exitstatus = waitforjob(jp, (int *)NULL);
 528                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 529                 INTON;
 530         }
 531 }
 532
 533
 534
 535 /*
 536  * Execute a command inside back quotes.  If it's a builtin command, we
 537  * want to save its output in a block obtained from malloc.  Otherwise
 538  * we fork off a subprocess and get the output of the command via a pipe.
 539  * Should be called with interrupts off.
 540  */
 541
 542 void
 543 evalbackcmd(union node *n, struct backcmd *result)
 544 {
 545         int pip[2];
 546         struct job *jp;
 547         struct stackmark smark;         /* unnecessary */
 548
 549         setstackmark(&smark);
 550         result->fd = -1;
 551         result->buf = NULL;
 552         result->nleft = 0;
 553         result->jp = NULL;
 554         if (n == NULL) {
 555                 exitstatus = 0;
 556                 goto out;
 557         }
 558         if (n->type == NCMD) {
 559                 exitstatus = oexitstatus;
 560                 evalcommand(n, EV_BACKCMD, result);
 561         } else {
 562                 exitstatus = 0;
 563                 if (pipe(pip) < 0)
 564                         error("Pipe call failed: %s", strerror(errno));
 565                 jp = makejob(n, 1);
 566                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 567                         FORCEINTON;
 568                         close(pip[0]);
 569                         if (pip[1] != 1) {
 570                                 close(1);
 571                                 copyfd(pip[1], 1);
 572                                 close(pip[1]);
 573                         }
 574                         evaltree(n, EV_EXIT);
 575                 }
 576                 close(pip[1]);
 577                 result->fd = pip[0];
 578                 result->jp = jp;
 579         }
 580 out:
 581         popstackmark(&smark);
 582         TRACE(("evalbackcmd done: fd=%d buf=0x%x nleft=%d jp=0x%x\n",
 583                 result->fd, result->buf, result->nleft, result->jp));
 584 }
 585
 586
 587
 588 /*
 589  * Execute a simple command.
 590  */
 591
 592 STATIC void
 593 evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
 594 {
 595         struct stackmark smark;
 596         union node *argp;
 597         struct arglist arglist;
 598         struct arglist varlist;
 599         char **argv;
 600         int argc;
 601         char **envp;
 602         int varflag;
 603         struct strlist *sp;
 604         int mode;
 605         int pip[2];
 606         struct cmdentry cmdentry;
 607         struct job *jp;
 608         struct jmploc jmploc;
 609         struct jmploc *volatile savehandler;
 610         char *volatile savecmdname;
 611         volatile struct shparam saveparam;
 612         struct localvar *volatile savelocalvars;
 613         volatile int e;
 614         char *lastarg;
 615         int realstatus;
 616         int do_clearcmdentry;
 617 #if __GNUC__
 618         /* Avoid longjmp clobbering */
 619         (void) &argv;
 620         (void) &argc;
 621         (void) &lastarg;
 622         (void) &flags;
 623         (void) &do_clearcmdentry;
 624 #endif
 625
 626         /* First expand the arguments. */
 627         TRACE(("evalcommand(0x%lx, %d) called\n", (long)cmd, flags));
 628         setstackmark(&smark);
 629         arglist.lastp = &arglist.list;
 630         varlist.lastp = &varlist.list;
 631         varflag = 1;
 632         do_clearcmdentry = 0;
 633         oexitstatus = exitstatus;
 634         exitstatus = 0;
 635         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 636                 char *p = argp->narg.text;
 637                 if (varflag && is_name(*p)) {
 638                         do {
 639                                 p++;
 640                         } while (is_in_name(*p));
 641                         if (*p == '=') {
 642                                 expandarg(argp, &varlist, EXP_VARTILDE);
 643                                 continue;
 644                         }
 645                 }
 646                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 647                 varflag = 0;
 648         }
 649         *arglist.lastp = NULL;
 650         *varlist.lastp = NULL;
 651         expredir(cmd->ncmd.redirect);
 652         argc = 0;
 653         for (sp = arglist.list ; sp ; sp = sp->next)
 654                 argc++;
 655         argv = stalloc(sizeof (char *) * (argc + 1));
 656
 657         for (sp = arglist.list ; sp ; sp = sp->next) {
 658                 TRACE(("evalcommand arg: %s\n", sp->text));
 659                 *argv++ = sp->text;
 660         }
 661         *argv = NULL;
 662         lastarg = NULL;
 663         if (iflag && funcnest == 0 && argc > 0)
 664                 lastarg = argv[-1];
 665         argv -= argc;
 666
 667         /* Print the command if xflag is set. */
 668         if (xflag) {
 669                 outc('+', &errout);
 670                 for (sp = varlist.list ; sp ; sp = sp->next) {
 671                         outc(' ', &errout);
 672                         out2str(sp->text);
 673                 }
 674                 for (sp = arglist.list ; sp ; sp = sp->next) {
 675                         outc(' ', &errout);
 676                         out2str(sp->text);
 677                 }
 678                 outc('\n', &errout);
 679                 flushout(&errout);
 680         }
 681
 682         /* Now locate the command. */
 683         if (argc == 0) {
 684                 cmdentry.cmdtype = CMDBUILTIN;
 685                 cmdentry.u.index = BLTINCMD;
 686         } else {
 687                 static const char PATH[] = "PATH=";
 688                 char *path = pathval();
 689
 690                 /*
 691                  * Modify the command lookup path, if a PATH= assignment
 692                  * is present
 693                  */
 694                 for (sp = varlist.list ; sp ; sp = sp->next)
 695                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 696                                 path = sp->text + sizeof(PATH) - 1;
 697                                 /*
 698                                  * On `PATH=... command`, we need to make
 699                                  * sure that the command isn't using the
 700                                  * non-updated hash table of the outer PATH
 701                                  * setting and we need to make sure that
 702                                  * the hash table isn't filled with items
 703                                  * from the temporary setting.
 704                                  *
 705                                  * It would be better to forbit using and
 706                                  * updating the table while this command
 707                                  * runs, by the command finding mechanism
 708                                  * is heavily integrated with hash handling,
 709                                  * so we just delete the hash before and after
 710                                  * the command runs. Partly deleting like
 711                                  * changepatch() does doesn't seem worth the
 712                                  * bookinging effort, since most such runs add
 713                                  * diretories in front of the new PATH.
 714                                  */
 715                                 clearcmdentry(0);
 716                                 do_clearcmdentry = 1;
 717                         }
 718
 719                 find_command(argv[0], &cmdentry, 1, path);
 720                 if (cmdentry.cmdtype == CMDUNKNOWN) {   /* command not found */
 721                         exitstatus = 127;
 722                         flushout(&errout);
 723                         return;
 724                 }
 725                 /* implement the bltin builtin here */
 726                 if (cmdentry.cmdtype == CMDBUILTIN && cmdentry.u.index == BLTINCMD) {
 727                         for (;;) {
 728                                 argv++;
 729                                 if (--argc == 0)
 730                                         break;
 731                                 if ((cmdentry.u.index = find_builtin(*argv)) < 0) {
 732                                         outfmt(&errout, "%s: not found\n", *argv);
 733                                         exitstatus = 127;
 734                                         flushout(&errout);
 735                                         return;
 736                                 }
 737                                 if (cmdentry.u.index != BLTINCMD)
 738                                         break;
 739                         }
 740                 }
 741         }
 742
 743         /* Fork off a child process if necessary. */
 744         if (cmd->ncmd.backgnd
 745          || (cmdentry.cmdtype == CMDNORMAL
 746             && ((flags & EV_EXIT) == 0 || Tflag))
 747          || ((flags & EV_BACKCMD) != 0
 748             && (cmdentry.cmdtype != CMDBUILTIN
 749                  || cmdentry.u.index == CDCMD
 750                  || cmdentry.u.index == DOTCMD
 751                  || cmdentry.u.index == EVALCMD))
 752          || (cmdentry.cmdtype == CMDBUILTIN &&
 753             cmdentry.u.index == COMMANDCMD)) {
 754                 jp = makejob(cmd, 1);
 755                 mode = cmd->ncmd.backgnd;
 756                 if (flags & EV_BACKCMD) {
 757                         mode = FORK_NOJOB;
 758                         if (pipe(pip) < 0)
 759                                 error("Pipe call failed: %s", strerror(errno));
 760                 }
 761                 if (forkshell(jp, cmd, mode) != 0)
 762                         goto parent;    /* at end of routine */
 763                 if (flags & EV_BACKCMD) {
 764                         FORCEINTON;
 765                         close(pip[0]);
 766                         if (pip[1] != 1) {
 767                                 close(1);
 768                                 copyfd(pip[1], 1);
 769                                 close(pip[1]);
 770                         }
 771                 }
 772                 flags |= EV_EXIT;
 773         }
 774
 775         /* This is the child process if a fork occurred. */
 776         /* Execute the command. */
 777         if (cmdentry.cmdtype == CMDFUNCTION) {
 778 #ifdef DEBUG
 779                 trputs("Shell function:  ");  trargs(argv);
 780 #endif
 781                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
 782                 saveparam = shellparam;
 783                 shellparam.malloc = 0;
 784                 shellparam.reset = 1;
 785                 shellparam.nparam = argc - 1;
 786                 shellparam.p = argv + 1;
 787                 shellparam.optnext = NULL;
 788                 INTOFF;
 789                 savelocalvars = localvars;
 790                 localvars = NULL;
 791                 INTON;
 792                 if (setjmp(jmploc.loc)) {
 793                         if (exception == EXSHELLPROC)
 794                                 freeparam((struct shparam *)&saveparam);
 795                         else {
 796                                 freeparam(&shellparam);
 797                                 shellparam = saveparam;
 798                         }
 799                         poplocalvars();
 800                         localvars = savelocalvars;
 801                         handler = savehandler;
 802                         longjmp(handler->loc, 1);
 803                 }
 804                 savehandler = handler;
 805                 handler = &jmploc;
 806                 for (sp = varlist.list ; sp ; sp = sp->next)
 807                         mklocal(sp->text);
 808                 funcnest++;
 809                 if (flags & EV_TESTED)
 810                         evaltree(cmdentry.u.func, EV_TESTED);
 811                 else
 812                         evaltree(cmdentry.u.func, 0);
 813                 funcnest--;
 814                 INTOFF;
 815                 poplocalvars();
 816                 localvars = savelocalvars;
 817                 freeparam(&shellparam);
 818                 shellparam = saveparam;
 819                 handler = savehandler;
 820                 popredir();
 821                 INTON;
 822                 if (evalskip == SKIPFUNC) {
 823                         evalskip = 0;
 824                         skipcount = 0;
 825                 }
 826                 if (flags & EV_EXIT)
 827                         exitshell(exitstatus);
 828         } else if (cmdentry.cmdtype == CMDBUILTIN) {
 829 #ifdef DEBUG
 830                 trputs("builtin command:  ");  trargs(argv);
 831 #endif
 832                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
 833                 if (flags == EV_BACKCMD) {
 834                         memout.nleft = 0;
 835                         memout.nextc = memout.buf;
 836                         memout.bufsize = 64;
 837                         mode |= REDIR_BACKQ;
 838                 }
 839                 redirect(cmd->ncmd.redirect, mode);
 840                 savecmdname = commandname;
 841                 cmdenviron = varlist.list;
 842                 e = -1;
 843                 if (setjmp(jmploc.loc)) {
 844                         e = exception;
 845                         exitstatus = (e == EXINT)? SIGINT+128 : 2;
 846                         goto cmddone;
 847                 }
 848                 savehandler = handler;
 849                 handler = &jmploc;
 850                 commandname = argv[0];
 851                 argptr = argv + 1;
 852                 optptr = NULL;                  /* initialize nextopt */
 853                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
 854                 flushall();
 855 cmddone:
 856                 cmdenviron = NULL;
 857                 out1 = &output;
 858                 out2 = &errout;
 859                 freestdout();
 860                 if (e != EXSHELLPROC) {
 861                         commandname = savecmdname;
 862                         if (flags & EV_EXIT) {
 863                                 exitshell(exitstatus);
 864                         }
 865                 }
 866                 handler = savehandler;
 867                 if (e != -1) {
 868                         if ((e != EXERROR && e != EXEXEC)
 869                            || cmdentry.u.index == BLTINCMD
 870                            || cmdentry.u.index == DOTCMD
 871                            || cmdentry.u.index == EVALCMD
 872 #ifndef NO_HISTORY
 873                            || cmdentry.u.index == HISTCMD
 874 #endif
 875                            || cmdentry.u.index == EXECCMD
 876                            || cmdentry.u.index == COMMANDCMD)
 877                                 exraise(e);
 878                         FORCEINTON;
 879                 }
 880                 if (cmdentry.u.index != EXECCMD)
 881                         popredir();
 882                 if (flags == EV_BACKCMD) {
 883                         backcmd->buf = memout.buf;
 884                         backcmd->nleft = memout.nextc - memout.buf;
 885                         memout.buf = NULL;
 886                 }
 887         } else {
 888 #ifdef DEBUG
 889                 trputs("normal command:  ");  trargs(argv);
 890 #endif
 891                 clearredir();
 892                 redirect(cmd->ncmd.redirect, 0);
 893                 for (sp = varlist.list ; sp ; sp = sp->next)
 894                         setvareq(sp->text, VEXPORT|VSTACK);
 895                 envp = environment();
 896                 shellexec(argv, envp, pathval(), cmdentry.u.index);
 897                 /*NOTREACHED*/
 898         }
 899         goto out;
 900
 901 parent: /* parent process gets here (if we forked) */
 902         if (mode == 0) {        /* argument to fork */
 903                 INTOFF;
 904                 exitstatus = waitforjob(jp, &realstatus);
 905                 INTON;
 906                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
 907                         evalskip = SKIPBREAK;
 908                         skipcount = loopnest;
 909                 }
 910         } else if (mode == 2) {
 911                 backcmd->fd = pip[0];
 912                 close(pip[1]);
 913                 backcmd->jp = jp;
 914         }
 915
 916 out:
 917         if (lastarg)
 918                 setvar("_", lastarg, 0);
 919         if (do_clearcmdentry)
 920                 clearcmdentry(0);
 921         popstackmark(&smark);
 922 }
 923
 924
 925
 926 /*
 927  * Search for a command.  This is called before we fork so that the
 928  * location of the command will be available in the parent as well as
 929  * the child.  The check for "goodname" is an overly conservative
 930  * check that the name will not be subject to expansion.
 931  */
 932
 933 STATIC void
 934 prehash(union node *n)
 935 {
 936         struct cmdentry entry;
 937
 938         if (n->type == NCMD && n->ncmd.args)
 939                 if (goodname(n->ncmd.args->narg.text))
 940                         find_command(n->ncmd.args->narg.text, &entry, 0,
 941                                      pathval());
 942 }
 943
 944
 945
 946 /*
 947  * Builtin commands.  Builtin commands whose functions are closely
 948  * tied to evaluation are implemented here.
 949  */
 950
 951 /*
 952  * No command given, or a bltin command with no arguments.  Set the
 953  * specified variables.
 954  */
 955
 956 int
 957 bltincmd(int argc __unused, char **argv __unused)
 958 {
 959         listsetvar(cmdenviron);
 960         /*
 961          * Preserve exitstatus of a previous possible redirection
 962          * as POSIX mandates
 963          */
 964         return exitstatus;
 965 }
 966
 967
 968 /*
 969  * Handle break and continue commands.  Break, continue, and return are
 970  * all handled by setting the evalskip flag.  The evaluation routines
 971  * above all check this flag, and if it is set they start skipping
 972  * commands rather than executing them.  The variable skipcount is
 973  * the number of loops to break/continue, or the number of function
 974  * levels to return.  (The latter is always 1.)  It should probably
 975  * be an error to break out of more loops than exist, but it isn't
 976  * in the standard shell so we don't make it one here.
 977  */
 978
 979 int
 980 breakcmd(int argc, char **argv)
 981 {
 982         int n = argc > 1 ? number(argv[1]) : 1;
 983
 984         if (n > loopnest)
 985                 n = loopnest;
 986         if (n > 0) {
 987                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
 988                 skipcount = n;
 989         }
 990         return 0;
 991 }
 992
 993 /*
 994  * The `command' command.
 995  */
 996 int
 997 commandcmd(int argc, char **argv)
 998 {
 999         static char stdpath[] = _PATH_STDPATH;
1000         struct jmploc loc, *old;
1001         struct strlist *sp;
1002         char *path;
1003         int ch;
1004
1005         for (sp = cmdenviron; sp ; sp = sp->next)
1006                 setvareq(sp->text, VEXPORT|VSTACK);
1007         path = pathval();
1008
1009         optind = optreset = 1;
1010         opterr = 0;
1011         while ((ch = getopt(argc, argv, "p")) != -1) {
1012                 switch (ch) {
1013                 case 'p':
1014                         path = stdpath;
1015                         break;
1016                 case '?':
1017                 default:
1018                         error("unknown option: -%c", optopt);
1019                 }
1020         }
1021         argc -= optind;
1022         argv += optind;
1023
1024         if (argc != 0) {
1025                 old = handler;
1026                 handler = &loc;
1027                 if (setjmp(handler->loc) == 0)
1028                         shellexec(argv, environment(), path, 0);
1029                 handler = old;
1030                 if (exception == EXEXEC)
1031                         exit(exerrno);
1032                 exraise(exception);
1033         }
1034
1035         /*
1036          * Do nothing successfully if no command was specified;
1037          * ksh also does this.
1038          */
1039         exit(0);
1040 }
1041
1042
1043 /*
1044  * The return command.
1045  */
1046
1047 int
1048 returncmd(int argc, char **argv)
1049 {
1050         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1051
1052         if (funcnest) {
1053                 evalskip = SKIPFUNC;
1054                 skipcount = 1;
1055         } else {
1056                 /* skip the rest of the file */
1057                 evalskip = SKIPFILE;
1058                 skipcount = 1;
1059         }
1060         return ret;
1061 }
1062
1063
1064 int
1065 falsecmd(int argc __unused, char **argv __unused)
1066 {
1067         return 1;
1068 }
1069
1070
1071 int
1072 truecmd(int argc __unused, char **argv __unused)
1073 {
1074         return 0;
1075 }
1076
1077
1078 int
1079 execcmd(int argc, char **argv)
1080 {
1081         if (argc > 1) {
1082                 struct strlist *sp;
1083
1084                 iflag = 0;              /* exit on error */
1085                 mflag = 0;
1086                 optschanged();
1087                 for (sp = cmdenviron; sp ; sp = sp->next)
1088                         setvareq(sp->text, VEXPORT|VSTACK);
1089                 shellexec(argv + 1, environment(), pathval(), 0);
1090
1091         }
1092         return 0;
1093 }