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 1.101 2011/02/05 14:08:51 jilles Exp $
  38  */
  39
  40 #include <sys/time.h>
  41 #include <sys/resource.h>
  42 #include <sys/wait.h> /* For WIFSIGNALED(status) */
  43
  44 #include <errno.h>
  45 #include <paths.h>
  46 #include <signal.h>
  47 #include <stdlib.h>
  48 #include <unistd.h>
  49
  50 /*
  51  * Evaluate a command.
  52  */
  53
  54 #include "shell.h"
  55 #include "nodes.h"
  56 #include "syntax.h"
  57 #include "expand.h"
  58 #include "parser.h"
  59 #include "jobs.h"
  60 #include "eval.h"
  61 #include "builtins.h"
  62 #include "options.h"
  63 #include "exec.h"
  64 #include "redir.h"
  65 #include "input.h"
  66 #include "output.h"
  67 #include "trap.h"
  68 #include "var.h"
  69 #include "memalloc.h"
  70 #include "error.h"
  71 #include "show.h"
  72 #include "mystring.h"
  73 #ifndef NO_HISTORY
  74 #include "myhistedit.h"
  75 #endif
  76
  77
  78 int evalskip;                   /* set if we are skipping commands */
  79 static int skipcount;           /* number of levels to skip */
  80 MKINIT int loopnest;            /* current loop nesting level */
  81 int funcnest;                   /* depth of function calls */
  82 static int builtin_flags;       /* evalcommand flags for builtins */
  83
  84
  85 const char *commandname;
  86 struct strlist *cmdenviron;
  87 int exitstatus;                 /* exit status of last command */
  88 int oexitstatus;                /* saved exit status */
  89
  90
  91 static void evalloop(union node *, int);
  92 static void evalfor(union node *, int);
  93 static void evalcase(union node *, int);
  94 static void evalsubshell(union node *, int);
  95 static void evalredir(union node *, int);
  96 static void expredir(union node *);
  97 static void evalpipe(union node *);
  98 static int is_valid_fast_cmdsubst(union node *n);
  99 static void evalcommand(union node *, int, struct backcmd *);
 100 static void prehash(union node *);
 101
 102
 103 /*
 104  * Called to reset things after an exception.
 105  */
 106
 107 #ifdef mkinit
 108 INCLUDE "eval.h"
 109
 110 RESET {
 111         evalskip = 0;
 112         loopnest = 0;
 113         funcnest = 0;
 114 }
 115 #endif
 116
 117
 118
 119 /*
 120  * The eval command.
 121  */
 122
 123 int
 124 evalcmd(int argc, char **argv)
 125 {
 126         char *p;
 127         char *concat;
 128         char **ap;
 129
 130         if (argc > 1) {
 131                 p = argv[1];
 132                 if (argc > 2) {
 133                         STARTSTACKSTR(concat);
 134                         ap = argv + 2;
 135                         for (;;) {
 136                                 STPUTS(p, concat);
 137                                 if ((p = *ap++) == NULL)
 138                                         break;
 139                                 STPUTC(' ', concat);
 140                         }
 141                         STPUTC('\0', concat);
 142                         p = grabstackstr(concat);
 143                 }
 144                 evalstring(p, builtin_flags & EV_TESTED);
 145         } else
 146                 exitstatus = 0;
 147         return exitstatus;
 148 }
 149
 150
 151 /*
 152  * Execute a command or commands contained in a string.
 153  */
 154
 155 void
 156 evalstring(char *s, int flags)
 157 {
 158         union node *n;
 159         struct stackmark smark;
 160         int flags_exit;
 161         int any;
 162
 163         flags_exit = flags & EV_EXIT;
 164         flags &= ~EV_EXIT;
 165         any = 0;
 166         setstackmark(&smark);
 167         setinputstring(s, 1);
 168         while ((n = parsecmd(0)) != NEOF) {
 169                 if (n != NULL) {
 170                         if (flags_exit && preadateof())
 171                                 evaltree(n, flags | EV_EXIT);
 172                         else
 173                                 evaltree(n, flags);
 174                         any = 1;
 175                 }
 176                 popstackmark(&smark);
 177         }
 178         popfile();
 179         popstackmark(&smark);
 180         if (!any)
 181                 exitstatus = 0;
 182         if (flags_exit)
 183                 exitshell(exitstatus);
 184 }
 185
 186
 187 /*
 188  * Evaluate a parse tree.  The value is left in the global variable
 189  * exitstatus.
 190  */
 191
 192 void
 193 evaltree(union node *n, int flags)
 194 {
 195         int do_etest;
 196         union node *next;
 197
 198         do_etest = 0;
 199         if (n == NULL) {
 200                 TRACE(("evaltree(NULL) called\n"));
 201                 exitstatus = 0;
 202                 goto out;
 203         }
 204         do {
 205                 next = NULL;
 206 #ifndef NO_HISTORY
 207                 displayhist = 1;        /* show history substitutions done with fc */
 208 #endif
 209                 TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
 210                 switch (n->type) {
 211                 case NSEMI:
 212                         evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
 213                         if (evalskip)
 214                                 goto out;
 215                         next = n->nbinary.ch2;
 216                         break;
 217                 case NAND:
 218                         evaltree(n->nbinary.ch1, EV_TESTED);
 219                         if (evalskip || exitstatus != 0) {
 220                                 goto out;
 221                         }
 222                         next = n->nbinary.ch2;
 223                         break;
 224                 case NOR:
 225                         evaltree(n->nbinary.ch1, EV_TESTED);
 226                         if (evalskip || exitstatus == 0)
 227                                 goto out;
 228                         next = n->nbinary.ch2;
 229                         break;
 230                 case NREDIR:
 231                         evalredir(n, flags);
 232                         break;
 233                 case NSUBSHELL:
 234                         evalsubshell(n, flags);
 235                         do_etest = !(flags & EV_TESTED);
 236                         break;
 237                 case NBACKGND:
 238                         evalsubshell(n, flags);
 239                         break;
 240                 case NIF: {
 241                         evaltree(n->nif.test, EV_TESTED);
 242                         if (evalskip)
 243                                 goto out;
 244                         if (exitstatus == 0)
 245                                 next = n->nif.ifpart;
 246                         else if (n->nif.elsepart)
 247                                 next = n->nif.elsepart;
 248                         else
 249                                 exitstatus = 0;
 250                         break;
 251                 }
 252                 case NWHILE:
 253                 case NUNTIL:
 254                         evalloop(n, flags & ~EV_EXIT);
 255                         break;
 256                 case NFOR:
 257                         evalfor(n, flags & ~EV_EXIT);
 258                         break;
 259                 case NCASE:
 260                         evalcase(n, flags);
 261                         break;
 262                 case NDEFUN:
 263                         defun(n->narg.text, n->narg.next);
 264                         exitstatus = 0;
 265                         break;
 266                 case NNOT:
 267                         evaltree(n->nnot.com, EV_TESTED);
 268                         exitstatus = !exitstatus;
 269                         break;
 270
 271                 case NPIPE:
 272                         evalpipe(n);
 273                         do_etest = !(flags & EV_TESTED);
 274                         break;
 275                 case NCMD:
 276                         evalcommand(n, flags, NULL);
 277                         do_etest = !(flags & EV_TESTED);
 278                         break;
 279                 default:
 280                         out1fmt("Node type = %d\n", n->type);
 281                         flushout(&output);
 282                         break;
 283                 }
 284                 n = next;
 285         } while (n != NULL);
 286 out:
 287         if (pendingsigs)
 288                 dotrap();
 289         if ((flags & EV_EXIT) || (eflag && exitstatus != 0 && do_etest))
 290                 exitshell(exitstatus);
 291 }
 292
 293
 294 static void
 295 evalloop(union node *n, int flags)
 296 {
 297         int status;
 298
 299         loopnest++;
 300         status = 0;
 301         for (;;) {
 302                 evaltree(n->nbinary.ch1, EV_TESTED);
 303                 if (evalskip) {
 304 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
 305                                 evalskip = 0;
 306                                 continue;
 307                         }
 308                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 309                                 evalskip = 0;
 310                         if (evalskip == SKIPFUNC || evalskip == SKIPFILE)
 311                                 status = exitstatus;
 312                         break;
 313                 }
 314                 if (n->type == NWHILE) {
 315                         if (exitstatus != 0)
 316                                 break;
 317                 } else {
 318                         if (exitstatus == 0)
 319                                 break;
 320                 }
 321                 evaltree(n->nbinary.ch2, flags);
 322                 status = exitstatus;
 323                 if (evalskip)
 324                         goto skipping;
 325         }
 326         loopnest--;
 327         exitstatus = status;
 328 }
 329
 330
 331
 332 static void
 333 evalfor(union node *n, int flags)
 334 {
 335         struct arglist arglist;
 336         union node *argp;
 337         struct strlist *sp;
 338         struct stackmark smark;
 339
 340         setstackmark(&smark);
 341         arglist.lastp = &arglist.list;
 342         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 343                 oexitstatus = exitstatus;
 344                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 345                 if (evalskip)
 346                         goto out;
 347         }
 348         *arglist.lastp = NULL;
 349
 350         exitstatus = 0;
 351         loopnest++;
 352         for (sp = arglist.list ; sp ; sp = sp->next) {
 353                 setvar(n->nfor.var, sp->text, 0);
 354                 evaltree(n->nfor.body, flags);
 355                 if (evalskip) {
 356                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 357                                 evalskip = 0;
 358                                 continue;
 359                         }
 360                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 361                                 evalskip = 0;
 362                         break;
 363                 }
 364         }
 365         loopnest--;
 366 out:
 367         popstackmark(&smark);
 368 }
 369
 370
 371
 372 static void
 373 evalcase(union node *n, int flags)
 374 {
 375         union node *cp;
 376         union node *patp;
 377         struct arglist arglist;
 378         struct stackmark smark;
 379
 380         setstackmark(&smark);
 381         arglist.lastp = &arglist.list;
 382         oexitstatus = exitstatus;
 383         exitstatus = 0;
 384         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 385         for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
 386                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 387                         if (casematch(patp, arglist.list->text)) {
 388                                 if (evalskip == 0) {
 389                                         evaltree(cp->nclist.body, flags);
 390                                 }
 391                                 goto out;
 392                         }
 393                 }
 394         }
 395 out:
 396         popstackmark(&smark);
 397 }
 398
 399
 400
 401 /*
 402  * Kick off a subshell to evaluate a tree.
 403  */
 404
 405 static void
 406 evalsubshell(union node *n, int flags)
 407 {
 408         struct job *jp;
 409         int backgnd = (n->type == NBACKGND);
 410
 411         expredir(n->nredir.redirect);
 412         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
 413             forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
 414                 if (backgnd)
 415                         flags &=~ EV_TESTED;
 416                 redirect(n->nredir.redirect, 0);
 417                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 418         } else if (!backgnd) {
 419                 INTOFF;
 420                 exitstatus = waitforjob(jp, NULL);
 421                 INTON;
 422         }
 423 }
 424
 425
 426 /*
 427  * Evaluate a redirected compound command.
 428  */
 429
 430 static void
 431 evalredir(union node *n, int flags)
 432 {
 433         struct jmploc jmploc;
 434         struct jmploc *savehandler;
 435         volatile int in_redirect = 1;
 436
 437         expredir(n->nredir.redirect);
 438         savehandler = handler;
 439         if (setjmp(jmploc.loc)) {
 440                 int e;
 441
 442                 handler = savehandler;
 443                 e = exception;
 444                 if (e == EXERROR || e == EXEXEC) {
 445                         popredir();
 446                         if (in_redirect) {
 447                                 exitstatus = 2;
 448                                 return;
 449                         }
 450                 }
 451                 longjmp(handler->loc, 1);
 452         } else {
 453                 INTOFF;
 454                 handler = &jmploc;
 455                 redirect(n->nredir.redirect, REDIR_PUSH);
 456                 in_redirect = 0;
 457                 INTON;
 458                 evaltree(n->nredir.n, flags);
 459         }
 460         INTOFF;
 461         handler = savehandler;
 462         popredir();
 463         INTON;
 464 }
 465
 466
 467 /*
 468  * Compute the names of the files in a redirection list.
 469  */
 470
 471 static void
 472 expredir(union node *n)
 473 {
 474         union node *redir;
 475
 476         for (redir = n ; redir ; redir = redir->nfile.next) {
 477                 struct arglist fn;
 478                 fn.lastp = &fn.list;
 479                 oexitstatus = exitstatus;
 480                 switch (redir->type) {
 481                 case NFROM:
 482                 case NTO:
 483                 case NFROMTO:
 484                 case NAPPEND:
 485                 case NCLOBBER:
 486                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 487                         redir->nfile.expfname = fn.list->text;
 488                         break;
 489                 case NFROMFD:
 490                 case NTOFD:
 491                         if (redir->ndup.vname) {
 492                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
 493                                 fixredir(redir, fn.list->text, 1);
 494                         }
 495                         break;
 496                 }
 497         }
 498 }
 499
 500
 501
 502 /*
 503  * Evaluate a pipeline.  All the processes in the pipeline are children
 504  * of the process creating the pipeline.  (This differs from some versions
 505  * of the shell, which make the last process in a pipeline the parent
 506  * of all the rest.)
 507  */
 508
 509 static void
 510 evalpipe(union node *n)
 511 {
 512         struct job *jp;
 513         struct nodelist *lp;
 514         int pipelen;
 515         int prevfd;
 516         int pip[2];
 517
 518         TRACE(("evalpipe(%p) called\n", (void *)n));
 519         pipelen = 0;
 520         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
 521                 pipelen++;
 522         INTOFF;
 523         jp = makejob(n, pipelen);
 524         prevfd = -1;
 525         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
 526                 prehash(lp->n);
 527                 pip[1] = -1;
 528                 if (lp->next) {
 529                         if (pipe(pip) < 0) {
 530                                 if (prevfd >= 0)
 531                                         close(prevfd);
 532                                 error("Pipe call failed: %s", strerror(errno));
 533                         }
 534                 }
 535                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
 536                         INTON;
 537                         if (prevfd > 0) {
 538                                 dup2(prevfd, 0);
 539                                 close(prevfd);
 540                         }
 541                         if (pip[1] >= 0) {
 542                                 if (!(prevfd >= 0 && pip[0] == 0))
 543                                         close(pip[0]);
 544                                 if (pip[1] != 1) {
 545                                         dup2(pip[1], 1);
 546                                         close(pip[1]);
 547                                 }
 548                         }
 549                         evaltree(lp->n, EV_EXIT);
 550                 }
 551                 if (prevfd >= 0)
 552                         close(prevfd);
 553                 prevfd = pip[0];
 554                 close(pip[1]);
 555         }
 556         INTON;
 557         if (n->npipe.backgnd == 0) {
 558                 INTOFF;
 559                 exitstatus = waitforjob(jp, NULL);
 560                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 561                 INTON;
 562         }
 563 }
 564
 565
 566
 567 static int
 568 is_valid_fast_cmdsubst(union node *n)
 569 {
 570         union node *argp;
 571
 572         if (n->type != NCMD)
 573                 return 0;
 574         for (argp = n->ncmd.args ; argp ; argp = argp->narg.next)
 575                 if (expandhassideeffects(argp->narg.text))
 576                         return 0;
 577         return 1;
 578 }
 579
 580 /*
 581  * Execute a command inside back quotes.  If it's a builtin command, we
 582  * want to save its output in a block obtained from malloc.  Otherwise
 583  * we fork off a subprocess and get the output of the command via a pipe.
 584  * Should be called with interrupts off.
 585  */
 586
 587 void
 588 evalbackcmd(union node *n, struct backcmd *result)
 589 {
 590         int pip[2];
 591         struct job *jp;
 592         struct stackmark smark;         /* unnecessary */
 593         struct jmploc jmploc;
 594         struct jmploc *savehandler;
 595
 596         setstackmark(&smark);
 597         result->fd = -1;
 598         result->buf = NULL;
 599         result->nleft = 0;
 600         result->jp = NULL;
 601         if (n == NULL) {
 602                 exitstatus = 0;
 603                 goto out;
 604         }
 605         if (is_valid_fast_cmdsubst(n)) {
 606                 exitstatus = oexitstatus;
 607                 savehandler = handler;
 608                 if (setjmp(jmploc.loc)) {
 609                         if (exception == EXERROR || exception == EXEXEC)
 610                                 exitstatus = 2;
 611                         else if (exception != 0) {
 612                                 handler = savehandler;
 613                                 longjmp(handler->loc, 1);
 614                         }
 615                 } else {
 616                         handler = &jmploc;
 617                         evalcommand(n, EV_BACKCMD, result);
 618                 }
 619                 handler = savehandler;
 620         } else {
 621                 exitstatus = 0;
 622                 if (pipe(pip) < 0)
 623                         error("Pipe call failed: %s", strerror(errno));
 624                 jp = makejob(n, 1);
 625                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 626                         FORCEINTON;
 627                         close(pip[0]);
 628                         if (pip[1] != 1) {
 629                                 dup2(pip[1], 1);
 630                                 close(pip[1]);
 631                         }
 632                         evaltree(n, EV_EXIT);
 633                 }
 634                 close(pip[1]);
 635                 result->fd = pip[0];
 636                 result->jp = jp;
 637         }
 638 out:
 639         popstackmark(&smark);
 640         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 641                 result->fd, result->buf, result->nleft, result->jp));
 642 }
 643
 644 /*
 645  * Check if a builtin can safely be executed in the same process,
 646  * even though it should be in a subshell (command substitution).
 647  * Note that jobid, jobs, times and trap can show information not
 648  * available in a child process; this is deliberate.
 649  * The arguments should already have been expanded.
 650  */
 651 static int
 652 safe_builtin(int idx, int argc, char **argv)
 653 {
 654         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
 655             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
 656             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
 657             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
 658             idx == TYPECMD)
 659                 return (1);
 660         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 661             idx == UMASKCMD)
 662                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 663         if (idx == SETCMD)
 664                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 665                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 666                     argv[1][2] == '\0'));
 667         return (0);
 668 }
 669
 670 /*
 671  * Execute a simple command.
 672  * Note: This may or may not return if (flags & EV_EXIT).
 673  */
 674
 675 static void
 676 evalcommand(union node *cmd, int flgs, struct backcmd *backcmd)
 677 {
 678         struct stackmark smark;
 679         union node *argp;
 680         struct arglist arglist;
 681         struct arglist varlist;
 682         volatile int flags = flgs;
 683         char **volatile argv;
 684         volatile int argc;
 685         char **envp;
 686         int varflag;
 687         struct strlist *sp;
 688         int mode;
 689         int pip[2];
 690         struct cmdentry cmdentry;
 691         struct job *volatile jp;
 692         struct jmploc jmploc;
 693         struct jmploc *savehandler;
 694         const char *savecmdname;
 695         struct shparam saveparam;
 696         struct localvar *savelocalvars;
 697         struct parsefile *savetopfile;
 698         volatile int e;
 699         char *volatile lastarg;
 700         int realstatus;
 701         volatile int do_clearcmdentry;
 702         const char *path = pathval();
 703
 704         /* First expand the arguments. */
 705         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 706         setstackmark(&smark);
 707         arglist.lastp = &arglist.list;
 708         varlist.lastp = &varlist.list;
 709         varflag = 1;
 710         jp = NULL;
 711         do_clearcmdentry = 0;
 712         oexitstatus = exitstatus;
 713         exitstatus = 0;
 714         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 715                 char *p = argp->narg.text;
 716                 if (varflag && is_name(*p)) {
 717                         do {
 718                                 p++;
 719                         } while (is_in_name(*p));
 720                         if (*p == '=') {
 721                                 expandarg(argp, &varlist, EXP_VARTILDE);
 722                                 continue;
 723                         }
 724                 }
 725                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 726                 varflag = 0;
 727         }
 728         *arglist.lastp = NULL;
 729         *varlist.lastp = NULL;
 730         expredir(cmd->ncmd.redirect);
 731         argc = 0;
 732         for (sp = arglist.list ; sp ; sp = sp->next)
 733                 argc++;
 734         /* Add one slot at the beginning for tryexec(). */
 735         argv = stalloc(sizeof (char *) * (argc + 2));
 736         argv++;
 737
 738         for (sp = arglist.list ; sp ; sp = sp->next) {
 739                 TRACE(("evalcommand arg: %s\n", sp->text));
 740                 *argv++ = sp->text;
 741         }
 742         *argv = NULL;
 743         lastarg = NULL;
 744         if (iflag && funcnest == 0 && argc > 0)
 745                 lastarg = argv[-1];
 746         argv -= argc;
 747
 748         /* Print the command if xflag is set. */
 749         if (xflag) {
 750                 char sep = 0;
 751                 const char *p;
 752                 out2str(ps4val());
 753                 for (sp = varlist.list ; sp ; sp = sp->next) {
 754                         if (sep != 0)
 755                                 out2c(' ');
 756                         p = strchr(sp->text, '=');
 757                         if (p != NULL) {
 758                                 p++;
 759                                 outbin(sp->text, p - sp->text, out2);
 760                                 out2qstr(p);
 761                         } else
 762                                 out2qstr(sp->text);
 763                         sep = ' ';
 764                 }
 765                 for (sp = arglist.list ; sp ; sp = sp->next) {
 766                         if (sep != 0)
 767                                 out2c(' ');
 768                         /* Disambiguate command looking like assignment. */
 769                         if (sp == arglist.list &&
 770                                         strchr(sp->text, '=') != NULL &&
 771                                         strchr(sp->text, '\'') == NULL) {
 772                                 out2c('\'');
 773                                 out2str(sp->text);
 774                                 out2c('\'');
 775                         } else
 776                                 out2qstr(sp->text);
 777                         sep = ' ';
 778                 }
 779                 out2c('\n');
 780                 flushout(&errout);
 781         }
 782
 783         /* Now locate the command. */
 784         if (argc == 0) {
 785                 /* Variable assignment(s) without command */
 786                 cmdentry.cmdtype = CMDBUILTIN;
 787                 cmdentry.u.index = BLTINCMD;
 788                 cmdentry.special = 0;
 789         } else {
 790                 static const char PATH[] = "PATH=";
 791                 int cmd_flags = 0, bltinonly = 0;
 792
 793                 /*
 794                  * Modify the command lookup path, if a PATH= assignment
 795                  * is present
 796                  */
 797                 for (sp = varlist.list ; sp ; sp = sp->next)
 798                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 799                                 path = sp->text + sizeof(PATH) - 1;
 800                                 /*
 801                                  * On `PATH=... command`, we need to make
 802                                  * sure that the command isn't using the
 803                                  * non-updated hash table of the outer PATH
 804                                  * setting and we need to make sure that
 805                                  * the hash table isn't filled with items
 806                                  * from the temporary setting.
 807                                  *
 808                                  * It would be better to forbit using and
 809                                  * updating the table while this command
 810                                  * runs, by the command finding mechanism
 811                                  * is heavily integrated with hash handling,
 812                                  * so we just delete the hash before and after
 813                                  * the command runs. Partly deleting like
 814                                  * changepatch() does doesn't seem worth the
 815                                  * bookinging effort, since most such runs add
 816                                  * directories in front of the new PATH.
 817                                  */
 818                                 clearcmdentry();
 819                                 do_clearcmdentry = 1;
 820                         }
 821
 822                 for (;;) {
 823                         if (bltinonly) {
 824                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 825                                 if (cmdentry.u.index < 0) {
 826                                         cmdentry.u.index = BLTINCMD;
 827                                         argv--;
 828                                         argc++;
 829                                         break;
 830                                 }
 831                         } else
 832                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 833                         /* implement the bltin and command builtins here */
 834                         if (cmdentry.cmdtype != CMDBUILTIN)
 835                                 break;
 836                         if (cmdentry.u.index == BLTINCMD) {
 837                                 if (argc == 1)
 838                                         break;
 839                                 argv++;
 840                                 argc--;
 841                                 bltinonly = 1;
 842                         } else if (cmdentry.u.index == COMMANDCMD) {
 843                                 if (argc == 1)
 844                                         break;
 845                                 if (!strcmp(argv[1], "-p")) {
 846                                         if (argc == 2)
 847                                                 break;
 848                                         if (argv[2][0] == '-') {
 849                                                 if (strcmp(argv[2], "--"))
 850                                                         break;
 851                                                 if (argc == 3)
 852                                                         break;
 853                                                 argv += 3;
 854                                                 argc -= 3;
 855                                         } else {
 856                                                 argv += 2;
 857                                                 argc -= 2;
 858                                         }
 859                                         path = _PATH_STDPATH;
 860                                         clearcmdentry();
 861                                         do_clearcmdentry = 1;
 862                                 } else if (!strcmp(argv[1], "--")) {
 863                                         if (argc == 2)
 864                                                 break;
 865                                         argv += 2;
 866                                         argc -= 2;
 867                                 } else if (argv[1][0] == '-')
 868                                         break;
 869                                 else {
 870                                         argv++;
 871                                         argc--;
 872                                 }
 873                                 cmd_flags |= DO_NOFUNC;
 874                                 bltinonly = 0;
 875                         } else
 876                                 break;
 877                 }
 878                 /*
 879                  * Special builtins lose their special properties when
 880                  * called via 'command'.
 881                  */
 882                 if (cmd_flags & DO_NOFUNC)
 883                         cmdentry.special = 0;
 884         }
 885
 886         /* Fork off a child process if necessary. */
 887         if (cmd->ncmd.backgnd
 888          || ((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 889             && ((flags & EV_EXIT) == 0 || have_traps()))
 890          || ((flags & EV_BACKCMD) != 0
 891             && (cmdentry.cmdtype != CMDBUILTIN ||
 892                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 893                 jp = makejob(cmd, 1);
 894                 mode = cmd->ncmd.backgnd;
 895                 if (flags & EV_BACKCMD) {
 896                         mode = FORK_NOJOB;
 897                         if (pipe(pip) < 0)
 898                                 error("Pipe call failed: %s", strerror(errno));
 899                 }
 900                 if (forkshell(jp, cmd, mode) != 0)
 901                         goto parent;    /* at end of routine */
 902                 if (flags & EV_BACKCMD) {
 903                         FORCEINTON;
 904                         close(pip[0]);
 905                         if (pip[1] != 1) {
 906                                 dup2(pip[1], 1);
 907                                 close(pip[1]);
 908                         }
 909                 }
 910                 flags |= EV_EXIT;
 911         }
 912
 913         /* This is the child process if a fork occurred. */
 914         /* Execute the command. */
 915         if (cmdentry.cmdtype == CMDFUNCTION) {
 916 #ifdef DEBUG
 917                 trputs("Shell function:  ");  trargs(argv);
 918 #endif
 919                 saveparam = shellparam;
 920                 shellparam.malloc = 0;
 921                 shellparam.reset = 1;
 922                 shellparam.nparam = argc - 1;
 923                 shellparam.p = argv + 1;
 924                 shellparam.optnext = NULL;
 925                 INTOFF;
 926                 savelocalvars = localvars;
 927                 localvars = NULL;
 928                 reffunc(cmdentry.u.func);
 929                 savehandler = handler;
 930                 if (setjmp(jmploc.loc)) {
 931                         freeparam(&shellparam);
 932                         shellparam = saveparam;
 933                         if (exception == EXERROR || exception == EXEXEC)
 934                                 popredir();
 935                         unreffunc(cmdentry.u.func);
 936                         poplocalvars();
 937                         localvars = savelocalvars;
 938                         funcnest--;
 939                         handler = savehandler;
 940                         longjmp(handler->loc, 1);
 941                 }
 942                 handler = &jmploc;
 943                 funcnest++;
 944                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
 945                 INTON;
 946                 for (sp = varlist.list ; sp ; sp = sp->next)
 947                         mklocal(sp->text);
 948                 exitstatus = oexitstatus;
 949                 if (flags & EV_TESTED)
 950                         evaltree(getfuncnode(cmdentry.u.func), EV_TESTED);
 951                 else
 952                         evaltree(getfuncnode(cmdentry.u.func), 0);
 953                 INTOFF;
 954                 unreffunc(cmdentry.u.func);
 955                 poplocalvars();
 956                 localvars = savelocalvars;
 957                 freeparam(&shellparam);
 958                 shellparam = saveparam;
 959                 handler = savehandler;
 960                 funcnest--;
 961                 popredir();
 962                 INTON;
 963                 if (evalskip == SKIPFUNC) {
 964                         evalskip = 0;
 965                         skipcount = 0;
 966                 }
 967                 if (jp)
 968                         exitshell(exitstatus);
 969         } else if (cmdentry.cmdtype == CMDBUILTIN) {
 970 #ifdef DEBUG
 971                 trputs("builtin command:  ");  trargs(argv);
 972 #endif
 973                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
 974                 if (flags == EV_BACKCMD) {
 975                         memout.nleft = 0;
 976                         memout.nextc = memout.buf;
 977                         memout.bufsize = 64;
 978                         mode |= REDIR_BACKQ;
 979                         cmdentry.special = 0;
 980                 }
 981                 savecmdname = commandname;
 982                 savetopfile = getcurrentfile();
 983                 cmdenviron = varlist.list;
 984                 e = -1;
 985                 savehandler = handler;
 986                 if (setjmp(jmploc.loc)) {
 987                         e = exception;
 988                         exitstatus = (e == EXINT)? SIGINT+128 : 2;
 989                         goto cmddone;
 990                 }
 991                 handler = &jmploc;
 992                 redirect(cmd->ncmd.redirect, mode);
 993                 /*
 994                  * If there is no command word, redirection errors should
 995                  * not be fatal but assignment errors should.
 996                  */
 997                 if (argc == 0 && !(flags & EV_BACKCMD))
 998                         cmdentry.special = 1;
 999                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1000                 if (argc > 0)
1001                         bltinsetlocale();
1002                 commandname = argv[0];
1003                 argptr = argv + 1;
1004                 nextopt_optptr = NULL;          /* initialize nextopt */
1005                 builtin_flags = flags;
1006                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1007                 flushall();
1008 cmddone:
1009                 if (argc > 0)
1010                         bltinunsetlocale();
1011                 cmdenviron = NULL;
1012                 out1 = &output;
1013                 out2 = &errout;
1014                 freestdout();
1015                 handler = savehandler;
1016                 commandname = savecmdname;
1017                 if (jp)
1018                         exitshell(exitstatus);
1019                 if (flags == EV_BACKCMD) {
1020                         backcmd->buf = memout.buf;
1021                         backcmd->nleft = memout.nextc - memout.buf;
1022                         memout.buf = NULL;
1023                 }
1024                 if (cmdentry.u.index != EXECCMD &&
1025                                 (e == -1 || e == EXERROR || e == EXEXEC))
1026                         popredir();
1027                 if (e != -1) {
1028                         if ((e != EXERROR && e != EXEXEC)
1029                             || cmdentry.special)
1030                                 exraise(e);
1031                         popfilesupto(savetopfile);
1032                         if (flags != EV_BACKCMD)
1033                                 FORCEINTON;
1034                 }
1035         } else {
1036 #ifdef DEBUG
1037                 trputs("normal command:  ");  trargs(argv);
1038 #endif
1039                 redirect(cmd->ncmd.redirect, 0);
1040                 for (sp = varlist.list ; sp ; sp = sp->next)
1041                         setvareq(sp->text, VEXPORT|VSTACK);
1042                 envp = environment();
1043                 shellexec(argv, envp, path, cmdentry.u.index);
1044                 /*NOTREACHED*/
1045         }
1046         goto out;
1047
1048 parent: /* parent process gets here (if we forked) */
1049         if (mode == FORK_FG) {  /* argument to fork */
1050                 INTOFF;
1051                 exitstatus = waitforjob(jp, &realstatus);
1052                 INTON;
1053                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1054                         evalskip = SKIPBREAK;
1055                         skipcount = loopnest;
1056                 }
1057         } else if (mode == FORK_NOJOB) {
1058                 backcmd->fd = pip[0];
1059                 close(pip[1]);
1060                 backcmd->jp = jp;
1061         }
1062
1063 out:
1064         if (lastarg)
1065                 setvar("_", lastarg, 0);
1066         if (do_clearcmdentry)
1067                 clearcmdentry();
1068         popstackmark(&smark);
1069 }
1070
1071
1072
1073 /*
1074  * Search for a command.  This is called before we fork so that the
1075  * location of the command will be available in the parent as well as
1076  * the child.  The check for "goodname" is an overly conservative
1077  * check that the name will not be subject to expansion.
1078  */
1079
1080 static void
1081 prehash(union node *n)
1082 {
1083         struct cmdentry entry;
1084
1085         if (n && n->type == NCMD && n->ncmd.args)
1086                 if (goodname(n->ncmd.args->narg.text))
1087                         find_command(n->ncmd.args->narg.text, &entry, 0,
1088                                      pathval());
1089 }
1090
1091
1092
1093 /*
1094  * Builtin commands.  Builtin commands whose functions are closely
1095  * tied to evaluation are implemented here.
1096  */
1097
1098 /*
1099  * No command given, a bltin command with no arguments, or a bltin command
1100  * with an invalid name.
1101  */
1102
1103 int
1104 bltincmd(int argc, char **argv)
1105 {
1106         if (argc > 1) {
1107                 out2fmt_flush("%s: not found\n", argv[1]);
1108                 return 127;
1109         }
1110         /*
1111          * Preserve exitstatus of a previous possible redirection
1112          * as POSIX mandates
1113          */
1114         return exitstatus;
1115 }
1116
1117
1118 /*
1119  * Handle break and continue commands.  Break, continue, and return are
1120  * all handled by setting the evalskip flag.  The evaluation routines
1121  * above all check this flag, and if it is set they start skipping
1122  * commands rather than executing them.  The variable skipcount is
1123  * the number of loops to break/continue, or the number of function
1124  * levels to return.  (The latter is always 1.)  It should probably
1125  * be an error to break out of more loops than exist, but it isn't
1126  * in the standard shell so we don't make it one here.
1127  */
1128
1129 int
1130 breakcmd(int argc, char **argv)
1131 {
1132         int n = argc > 1 ? number(argv[1]) : 1;
1133
1134         if (n > loopnest)
1135                 n = loopnest;
1136         if (n > 0) {
1137                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1138                 skipcount = n;
1139         }
1140         return 0;
1141 }
1142
1143 /*
1144  * The `command' command.
1145  */
1146 int
1147 commandcmd(int argc, char **argv)
1148 {
1149         const char *path;
1150         int ch;
1151         int cmd = -1;
1152
1153         path = bltinlookup("PATH", 1);
1154
1155         optind = optreset = 1;
1156         opterr = 0;
1157         while ((ch = getopt(argc, argv, "pvV")) != -1) {
1158                 switch (ch) {
1159                 case 'p':
1160                         path = _PATH_STDPATH;
1161                         break;
1162                 case 'v':
1163                         cmd = TYPECMD_SMALLV;
1164                         break;
1165                 case 'V':
1166                         cmd = TYPECMD_BIGV;
1167                         break;
1168                 case '?':
1169                 default:
1170                         error("unknown option: -%c", optopt);
1171                 }
1172         }
1173         argc -= optind;
1174         argv += optind;
1175
1176         if (cmd != -1) {
1177                 if (argc != 1)
1178                         error("wrong number of arguments");
1179                 return typecmd_impl(2, argv - 1, cmd, path);
1180         }
1181         if (argc != 0)
1182                 error("commandcmd bad call");
1183
1184         /*
1185          * Do nothing successfully if no command was specified;
1186          * ksh also does this.
1187          */
1188         return(0);
1189 }
1190
1191
1192 /*
1193  * The return command.
1194  */
1195
1196 int
1197 returncmd(int argc, char **argv)
1198 {
1199         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1200
1201         if (funcnest) {
1202                 evalskip = SKIPFUNC;
1203                 skipcount = 1;
1204         } else {
1205                 /* skip the rest of the file */
1206                 evalskip = SKIPFILE;
1207                 skipcount = 1;
1208         }
1209         return ret;
1210 }
1211
1212
1213 int
1214 falsecmd(int argc __unused, char **argv __unused)
1215 {
1216         return 1;
1217 }
1218
1219
1220 int
1221 truecmd(int argc __unused, char **argv __unused)
1222 {
1223         return 0;
1224 }
1225
1226
1227 int
1228 execcmd(int argc, char **argv)
1229 {
1230         /*
1231          * Because we have historically not supported any options,
1232          * only treat "--" specially.
1233          */
1234         if (argc > 1 && strcmp(argv[1], "--") == 0)
1235                 argc--, argv++;
1236         if (argc > 1) {
1237                 struct strlist *sp;
1238
1239                 iflag = 0;              /* exit on error */
1240                 mflag = 0;
1241                 optschanged();
1242                 for (sp = cmdenviron; sp ; sp = sp->next)
1243                         setvareq(sp->text, VEXPORT|VSTACK);
1244                 shellexec(argv + 1, environment(), pathval(), 0);
1245
1246         }
1247         return 0;
1248 }
1249
1250
1251 int
1252 timescmd(int argc __unused, char **argv __unused)
1253 {
1254         struct rusage ru;
1255         long shumins, shsmins, chumins, chsmins;
1256         double shusecs, shssecs, chusecs, chssecs;
1257
1258         if (getrusage(RUSAGE_SELF, &ru) < 0)
1259                 return 1;
1260         shumins = ru.ru_utime.tv_sec / 60;
1261         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1262         shsmins = ru.ru_stime.tv_sec / 60;
1263         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1264         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1265                 return 1;
1266         chumins = ru.ru_utime.tv_sec / 60;
1267         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1268         chsmins = ru.ru_stime.tv_sec / 60;
1269         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1270         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1271             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1272         return 0;
1273 }