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 1.106 2011/06/04 11:28:42 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 && !nflag) {
 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                 exraise(EXEXIT);
 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 (eflag && exitstatus != 0 && do_etest)
 290                 exitshell(exitstatus);
 291         if (flags & EV_EXIT)
 292                 exraise(EXEXIT);
 293 }
 294
 295
 296 static void
 297 evalloop(union node *n, int flags)
 298 {
 299         int status;
 300
 301         loopnest++;
 302         status = 0;
 303         for (;;) {
 304                 evaltree(n->nbinary.ch1, EV_TESTED);
 305                 if (evalskip) {
 306 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
 307                                 evalskip = 0;
 308                                 continue;
 309                         }
 310                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 311                                 evalskip = 0;
 312                         if (evalskip == SKIPFUNC || evalskip == SKIPFILE)
 313                                 status = exitstatus;
 314                         break;
 315                 }
 316                 if (n->type == NWHILE) {
 317                         if (exitstatus != 0)
 318                                 break;
 319                 } else {
 320                         if (exitstatus == 0)
 321                                 break;
 322                 }
 323                 evaltree(n->nbinary.ch2, flags);
 324                 status = exitstatus;
 325                 if (evalskip)
 326                         goto skipping;
 327         }
 328         loopnest--;
 329         exitstatus = status;
 330 }
 331
 332
 333
 334 static void
 335 evalfor(union node *n, int flags)
 336 {
 337         struct arglist arglist;
 338         union node *argp;
 339         struct strlist *sp;
 340         struct stackmark smark;
 341
 342         setstackmark(&smark);
 343         arglist.lastp = &arglist.list;
 344         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 345                 oexitstatus = exitstatus;
 346                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 347                 if (evalskip)
 348                         goto out;
 349         }
 350         *arglist.lastp = NULL;
 351
 352         exitstatus = 0;
 353         loopnest++;
 354         for (sp = arglist.list ; sp ; sp = sp->next) {
 355                 setvar(n->nfor.var, sp->text, 0);
 356                 evaltree(n->nfor.body, flags);
 357                 if (evalskip) {
 358                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 359                                 evalskip = 0;
 360                                 continue;
 361                         }
 362                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 363                                 evalskip = 0;
 364                         break;
 365                 }
 366         }
 367         loopnest--;
 368 out:
 369         popstackmark(&smark);
 370 }
 371
 372
 373
 374 static void
 375 evalcase(union node *n, int flags)
 376 {
 377         union node *cp;
 378         union node *patp;
 379         struct arglist arglist;
 380         struct stackmark smark;
 381
 382         setstackmark(&smark);
 383         arglist.lastp = &arglist.list;
 384         oexitstatus = exitstatus;
 385         exitstatus = 0;
 386         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 387         for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
 388                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 389                         if (casematch(patp, arglist.list->text)) {
 390                                 if (evalskip == 0) {
 391                                         evaltree(cp->nclist.body, flags);
 392                                 }
 393                                 goto out;
 394                         }
 395                 }
 396         }
 397 out:
 398         popstackmark(&smark);
 399 }
 400
 401
 402
 403 /*
 404  * Kick off a subshell to evaluate a tree.
 405  */
 406
 407 static void
 408 evalsubshell(union node *n, int flags)
 409 {
 410         struct job *jp;
 411         int backgnd = (n->type == NBACKGND);
 412
 413         expredir(n->nredir.redirect);
 414         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
 415             forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
 416                 if (backgnd)
 417                         flags &=~ EV_TESTED;
 418                 redirect(n->nredir.redirect, 0);
 419                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 420         } else if (!backgnd) {
 421                 INTOFF;
 422                 exitstatus = waitforjob(jp, NULL);
 423                 INTON;
 424         } else
 425                 exitstatus = 0;
 426 }
 427
 428
 429 /*
 430  * Evaluate a redirected compound command.
 431  */
 432
 433 static void
 434 evalredir(union node *n, int flags)
 435 {
 436         struct jmploc jmploc;
 437         struct jmploc *savehandler;
 438         volatile int in_redirect = 1;
 439
 440         expredir(n->nredir.redirect);
 441         savehandler = handler;
 442         if (setjmp(jmploc.loc)) {
 443                 int e;
 444
 445                 handler = savehandler;
 446                 e = exception;
 447                 popredir();
 448                 if (e == EXERROR || e == EXEXEC) {
 449                         if (in_redirect) {
 450                                 exitstatus = 2;
 451                                 return;
 452                         }
 453                 }
 454                 longjmp(handler->loc, 1);
 455         } else {
 456                 INTOFF;
 457                 handler = &jmploc;
 458                 redirect(n->nredir.redirect, REDIR_PUSH);
 459                 in_redirect = 0;
 460                 INTON;
 461                 evaltree(n->nredir.n, flags);
 462         }
 463         INTOFF;
 464         handler = savehandler;
 465         popredir();
 466         INTON;
 467 }
 468
 469
 470 /*
 471  * Compute the names of the files in a redirection list.
 472  */
 473
 474 static void
 475 expredir(union node *n)
 476 {
 477         union node *redir;
 478
 479         for (redir = n ; redir ; redir = redir->nfile.next) {
 480                 struct arglist fn;
 481                 fn.lastp = &fn.list;
 482                 oexitstatus = exitstatus;
 483                 switch (redir->type) {
 484                 case NFROM:
 485                 case NTO:
 486                 case NFROMTO:
 487                 case NAPPEND:
 488                 case NCLOBBER:
 489                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 490                         redir->nfile.expfname = fn.list->text;
 491                         break;
 492                 case NFROMFD:
 493                 case NTOFD:
 494                         if (redir->ndup.vname) {
 495                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
 496                                 fixredir(redir, fn.list->text, 1);
 497                         }
 498                         break;
 499                 }
 500         }
 501 }
 502
 503
 504
 505 /*
 506  * Evaluate a pipeline.  All the processes in the pipeline are children
 507  * of the process creating the pipeline.  (This differs from some versions
 508  * of the shell, which make the last process in a pipeline the parent
 509  * of all the rest.)
 510  */
 511
 512 static void
 513 evalpipe(union node *n)
 514 {
 515         struct job *jp;
 516         struct nodelist *lp;
 517         int pipelen;
 518         int prevfd;
 519         int pip[2];
 520
 521         TRACE(("evalpipe(%p) called\n", (void *)n));
 522         pipelen = 0;
 523         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
 524                 pipelen++;
 525         INTOFF;
 526         jp = makejob(n, pipelen);
 527         prevfd = -1;
 528         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
 529                 prehash(lp->n);
 530                 pip[1] = -1;
 531                 if (lp->next) {
 532                         if (pipe(pip) < 0) {
 533                                 if (prevfd >= 0)
 534                                         close(prevfd);
 535                                 error("Pipe call failed: %s", strerror(errno));
 536                         }
 537                 }
 538                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
 539                         INTON;
 540                         if (prevfd > 0) {
 541                                 dup2(prevfd, 0);
 542                                 close(prevfd);
 543                         }
 544                         if (pip[1] >= 0) {
 545                                 if (!(prevfd >= 0 && pip[0] == 0))
 546                                         close(pip[0]);
 547                                 if (pip[1] != 1) {
 548                                         dup2(pip[1], 1);
 549                                         close(pip[1]);
 550                                 }
 551                         }
 552                         evaltree(lp->n, EV_EXIT);
 553                 }
 554                 if (prevfd >= 0)
 555                         close(prevfd);
 556                 prevfd = pip[0];
 557                 if (pip[1] != -1)
 558                         close(pip[1]);
 559         }
 560         INTON;
 561         if (n->npipe.backgnd == 0) {
 562                 INTOFF;
 563                 exitstatus = waitforjob(jp, NULL);
 564                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 565                 INTON;
 566         } else
 567                 exitstatus = 0;
 568 }
 569
 570
 571
 572 static int
 573 is_valid_fast_cmdsubst(union node *n)
 574 {
 575         union node *argp;
 576
 577         if (n->type != NCMD)
 578                 return 0;
 579         for (argp = n->ncmd.args ; argp ; argp = argp->narg.next)
 580                 if (expandhassideeffects(argp->narg.text))
 581                         return 0;
 582         return 1;
 583 }
 584
 585 /*
 586  * Execute a command inside back quotes.  If it's a builtin command, we
 587  * want to save its output in a block obtained from malloc.  Otherwise
 588  * we fork off a subprocess and get the output of the command via a pipe.
 589  * Should be called with interrupts off.
 590  */
 591
 592 void
 593 evalbackcmd(union node *n, struct backcmd *result)
 594 {
 595         int pip[2];
 596         struct job *jp;
 597         struct stackmark smark;         /* unnecessary */
 598         struct jmploc jmploc;
 599         struct jmploc *savehandler;
 600
 601         setstackmark(&smark);
 602         result->fd = -1;
 603         result->buf = NULL;
 604         result->nleft = 0;
 605         result->jp = NULL;
 606         if (n == NULL) {
 607                 exitstatus = 0;
 608                 goto out;
 609         }
 610         if (is_valid_fast_cmdsubst(n)) {
 611                 exitstatus = oexitstatus;
 612                 savehandler = handler;
 613                 if (setjmp(jmploc.loc)) {
 614                         if (exception == EXERROR || exception == EXEXEC)
 615                                 exitstatus = 2;
 616                         else if (exception != 0) {
 617                                 handler = savehandler;
 618                                 longjmp(handler->loc, 1);
 619                         }
 620                 } else {
 621                         handler = &jmploc;
 622                         evalcommand(n, EV_BACKCMD, result);
 623                 }
 624                 handler = savehandler;
 625         } else {
 626                 exitstatus = 0;
 627                 if (pipe(pip) < 0)
 628                         error("Pipe call failed: %s", strerror(errno));
 629                 jp = makejob(n, 1);
 630                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 631                         FORCEINTON;
 632                         close(pip[0]);
 633                         if (pip[1] != 1) {
 634                                 dup2(pip[1], 1);
 635                                 close(pip[1]);
 636                         }
 637                         evaltree(n, EV_EXIT);
 638                 }
 639                 close(pip[1]);
 640                 result->fd = pip[0];
 641                 result->jp = jp;
 642         }
 643 out:
 644         popstackmark(&smark);
 645         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 646                 result->fd, result->buf, result->nleft, result->jp));
 647 }
 648
 649 /*
 650  * Check if a builtin can safely be executed in the same process,
 651  * even though it should be in a subshell (command substitution).
 652  * Note that jobid, jobs, times and trap can show information not
 653  * available in a child process; this is deliberate.
 654  * The arguments should already have been expanded.
 655  */
 656 static int
 657 safe_builtin(int idx, int argc, char **argv)
 658 {
 659         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
 660             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
 661             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
 662             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
 663             idx == TYPECMD)
 664                 return (1);
 665         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 666             idx == UMASKCMD)
 667                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 668         if (idx == SETCMD)
 669                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 670                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 671                     argv[1][2] == '\0'));
 672         return (0);
 673 }
 674
 675 /*
 676  * Execute a simple command.
 677  * Note: This may or may not return if (flags & EV_EXIT).
 678  */
 679
 680 static void
 681 evalcommand(union node *cmd, int flgs, struct backcmd *backcmd)
 682 {
 683         struct stackmark smark;
 684         union node *argp;
 685         struct arglist arglist;
 686         struct arglist varlist;
 687         volatile int flags = flgs;
 688         char **volatile argv;
 689         volatile int argc;
 690         char **envp;
 691         int varflag;
 692         struct strlist *sp;
 693         int mode;
 694         int pip[2];
 695         struct cmdentry cmdentry;
 696         struct job *volatile jp;
 697         struct jmploc jmploc;
 698         struct jmploc *savehandler;
 699         const char *savecmdname;
 700         struct shparam saveparam;
 701         struct localvar *savelocalvars;
 702         struct parsefile *savetopfile;
 703         volatile int e;
 704         char *volatile lastarg;
 705         int realstatus;
 706         volatile int do_clearcmdentry;
 707         const char *path = pathval();
 708
 709         /* First expand the arguments. */
 710         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 711         setstackmark(&smark);
 712         arglist.lastp = &arglist.list;
 713         varlist.lastp = &varlist.list;
 714         varflag = 1;
 715         jp = NULL;
 716         do_clearcmdentry = 0;
 717         oexitstatus = exitstatus;
 718         exitstatus = 0;
 719         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 720                 if (varflag && isassignment(argp->narg.text)) {
 721                         expandarg(argp, &varlist, EXP_VARTILDE);
 722                         continue;
 723                 }
 724                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 725                 varflag = 0;
 726         }
 727         *arglist.lastp = NULL;
 728         *varlist.lastp = NULL;
 729         expredir(cmd->ncmd.redirect);
 730         argc = 0;
 731         for (sp = arglist.list ; sp ; sp = sp->next)
 732                 argc++;
 733         /* Add one slot at the beginning for tryexec(). */
 734         argv = stalloc(sizeof (char *) * (argc + 2));
 735         argv++;
 736
 737         for (sp = arglist.list ; sp ; sp = sp->next) {
 738                 TRACE(("evalcommand arg: %s\n", sp->text));
 739                 *argv++ = sp->text;
 740         }
 741         *argv = NULL;
 742         lastarg = NULL;
 743         if (iflag && funcnest == 0 && argc > 0)
 744                 lastarg = argv[-1];
 745         argv -= argc;
 746
 747         /* Print the command if xflag is set. */
 748         if (xflag) {
 749                 char sep = 0;
 750                 const char *p;
 751                 out2str(ps4val());
 752                 for (sp = varlist.list ; sp ; sp = sp->next) {
 753                         if (sep != 0)
 754                                 out2c(' ');
 755                         p = strchr(sp->text, '=');
 756                         if (p != NULL) {
 757                                 p++;
 758                                 outbin(sp->text, p - sp->text, out2);
 759                                 out2qstr(p);
 760                         } else
 761                                 out2qstr(sp->text);
 762                         sep = ' ';
 763                 }
 764                 for (sp = arglist.list ; sp ; sp = sp->next) {
 765                         if (sep != 0)
 766                                 out2c(' ');
 767                         /* Disambiguate command looking like assignment. */
 768                         if (sp == arglist.list &&
 769                                         strchr(sp->text, '=') != NULL &&
 770                                         strchr(sp->text, '\'') == NULL) {
 771                                 out2c('\'');
 772                                 out2str(sp->text);
 773                                 out2c('\'');
 774                         } else
 775                                 out2qstr(sp->text);
 776                         sep = ' ';
 777                 }
 778                 out2c('\n');
 779                 flushout(&errout);
 780         }
 781
 782         /* Now locate the command. */
 783         if (argc == 0) {
 784                 /* Variable assignment(s) without command */
 785                 cmdentry.cmdtype = CMDBUILTIN;
 786                 cmdentry.u.index = BLTINCMD;
 787                 cmdentry.special = 0;
 788         } else {
 789                 static const char PATH[] = "PATH=";
 790                 int cmd_flags = 0, bltinonly = 0;
 791
 792                 /*
 793                  * Modify the command lookup path, if a PATH= assignment
 794                  * is present
 795                  */
 796                 for (sp = varlist.list ; sp ; sp = sp->next)
 797                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 798                                 path = sp->text + sizeof(PATH) - 1;
 799                                 /*
 800                                  * On `PATH=... command`, we need to make
 801                                  * sure that the command isn't using the
 802                                  * non-updated hash table of the outer PATH
 803                                  * setting and we need to make sure that
 804                                  * the hash table isn't filled with items
 805                                  * from the temporary setting.
 806                                  *
 807                                  * It would be better to forbit using and
 808                                  * updating the table while this command
 809                                  * runs, by the command finding mechanism
 810                                  * is heavily integrated with hash handling,
 811                                  * so we just delete the hash before and after
 812                                  * the command runs. Partly deleting like
 813                                  * changepatch() does doesn't seem worth the
 814                                  * bookinging effort, since most such runs add
 815                                  * directories in front of the new PATH.
 816                                  */
 817                                 clearcmdentry();
 818                                 do_clearcmdentry = 1;
 819                         }
 820
 821                 for (;;) {
 822                         if (bltinonly) {
 823                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 824                                 if (cmdentry.u.index < 0) {
 825                                         cmdentry.u.index = BLTINCMD;
 826                                         argv--;
 827                                         argc++;
 828                                         break;
 829                                 }
 830                         } else
 831                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 832                         /* implement the bltin and command builtins here */
 833                         if (cmdentry.cmdtype != CMDBUILTIN)
 834                                 break;
 835                         if (cmdentry.u.index == BLTINCMD) {
 836                                 if (argc == 1)
 837                                         break;
 838                                 argv++;
 839                                 argc--;
 840                                 bltinonly = 1;
 841                         } else if (cmdentry.u.index == COMMANDCMD) {
 842                                 if (argc == 1)
 843                                         break;
 844                                 if (!strcmp(argv[1], "-p")) {
 845                                         if (argc == 2)
 846                                                 break;
 847                                         if (argv[2][0] == '-') {
 848                                                 if (strcmp(argv[2], "--"))
 849                                                         break;
 850                                                 if (argc == 3)
 851                                                         break;
 852                                                 argv += 3;
 853                                                 argc -= 3;
 854                                         } else {
 855                                                 argv += 2;
 856                                                 argc -= 2;
 857                                         }
 858                                         path = _PATH_STDPATH;
 859                                         clearcmdentry();
 860                                         do_clearcmdentry = 1;
 861                                 } else if (!strcmp(argv[1], "--")) {
 862                                         if (argc == 2)
 863                                                 break;
 864                                         argv += 2;
 865                                         argc -= 2;
 866                                 } else if (argv[1][0] == '-')
 867                                         break;
 868                                 else {
 869                                         argv++;
 870                                         argc--;
 871                                 }
 872                                 cmd_flags |= DO_NOFUNC;
 873                                 bltinonly = 0;
 874                         } else
 875                                 break;
 876                 }
 877                 /*
 878                  * Special builtins lose their special properties when
 879                  * called via 'command'.
 880                  */
 881                 if (cmd_flags & DO_NOFUNC)
 882                         cmdentry.special = 0;
 883         }
 884
 885         /* Fork off a child process if necessary. */
 886         if (cmd->ncmd.backgnd
 887          || ((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 888             && ((flags & EV_EXIT) == 0 || have_traps()))
 889          || ((flags & EV_BACKCMD) != 0
 890             && (cmdentry.cmdtype != CMDBUILTIN ||
 891                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 892                 jp = makejob(cmd, 1);
 893                 mode = cmd->ncmd.backgnd;
 894                 if (flags & EV_BACKCMD) {
 895                         mode = FORK_NOJOB;
 896                         if (pipe(pip) < 0)
 897                                 error("Pipe call failed: %s", strerror(errno));
 898                 }
 899                 if (forkshell(jp, cmd, mode) != 0)
 900                         goto parent;    /* at end of routine */
 901                 if (flags & EV_BACKCMD) {
 902                         FORCEINTON;
 903                         close(pip[0]);
 904                         if (pip[1] != 1) {
 905                                 dup2(pip[1], 1);
 906                                 close(pip[1]);
 907                         }
 908                 }
 909                 flags |= EV_EXIT;
 910         }
 911
 912         /* This is the child process if a fork occurred. */
 913         /* Execute the command. */
 914         if (cmdentry.cmdtype == CMDFUNCTION) {
 915 #ifdef DEBUG
 916                 trputs("Shell function:  ");  trargs(argv);
 917 #endif
 918                 saveparam = shellparam;
 919                 shellparam.malloc = 0;
 920                 shellparam.reset = 1;
 921                 shellparam.nparam = argc - 1;
 922                 shellparam.p = argv + 1;
 923                 shellparam.optnext = NULL;
 924                 INTOFF;
 925                 savelocalvars = localvars;
 926                 localvars = NULL;
 927                 reffunc(cmdentry.u.func);
 928                 savehandler = handler;
 929                 if (setjmp(jmploc.loc)) {
 930                         freeparam(&shellparam);
 931                         shellparam = saveparam;
 932                         popredir();
 933                         unreffunc(cmdentry.u.func);
 934                         poplocalvars();
 935                         localvars = savelocalvars;
 936                         funcnest--;
 937                         handler = savehandler;
 938                         longjmp(handler->loc, 1);
 939                 }
 940                 handler = &jmploc;
 941                 funcnest++;
 942                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
 943                 INTON;
 944                 for (sp = varlist.list ; sp ; sp = sp->next)
 945                         mklocal(sp->text);
 946                 exitstatus = oexitstatus;
 947                 evaltree(getfuncnode(cmdentry.u.func),
 948                     flags & (EV_TESTED | EV_EXIT));
 949                 INTOFF;
 950                 unreffunc(cmdentry.u.func);
 951                 poplocalvars();
 952                 localvars = savelocalvars;
 953                 freeparam(&shellparam);
 954                 shellparam = saveparam;
 955                 handler = savehandler;
 956                 funcnest--;
 957                 popredir();
 958                 INTON;
 959                 if (evalskip == SKIPFUNC) {
 960                         evalskip = 0;
 961                         skipcount = 0;
 962                 }
 963                 if (jp)
 964                         exitshell(exitstatus);
 965         } else if (cmdentry.cmdtype == CMDBUILTIN) {
 966 #ifdef DEBUG
 967                 trputs("builtin command:  ");  trargs(argv);
 968 #endif
 969                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
 970                 if (flags == EV_BACKCMD) {
 971                         memout.nleft = 0;
 972                         memout.nextc = memout.buf;
 973                         memout.bufsize = 64;
 974                         mode |= REDIR_BACKQ;
 975                         cmdentry.special = 0;
 976                 }
 977                 savecmdname = commandname;
 978                 savetopfile = getcurrentfile();
 979                 cmdenviron = varlist.list;
 980                 e = -1;
 981                 savehandler = handler;
 982                 if (setjmp(jmploc.loc)) {
 983                         e = exception;
 984                         if (e == EXINT)
 985                                 exitstatus = SIGINT+128;
 986                         else if (e != EXEXIT)
 987                                 exitstatus = 2;
 988                         goto cmddone;
 989                 }
 990                 handler = &jmploc;
 991                 redirect(cmd->ncmd.redirect, mode);
 992                 /*
 993                  * If there is no command word, redirection errors should
 994                  * not be fatal but assignment errors should.
 995                  */
 996                 if (argc == 0 && !(flags & EV_BACKCMD))
 997                         cmdentry.special = 1;
 998                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
 999                 if (argc > 0)
1000                         bltinsetlocale();
1001                 commandname = argv[0];
1002                 argptr = argv + 1;
1003                 nextopt_optptr = NULL;          /* initialize nextopt */
1004                 builtin_flags = flags;
1005                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1006                 flushall();
1007 cmddone:
1008                 if (argc > 0)
1009                         bltinunsetlocale();
1010                 cmdenviron = NULL;
1011                 out1 = &output;
1012                 out2 = &errout;
1013                 freestdout();
1014                 handler = savehandler;
1015                 commandname = savecmdname;
1016                 if (jp)
1017                         exitshell(exitstatus);
1018                 if (flags == EV_BACKCMD) {
1019                         backcmd->buf = memout.buf;
1020                         backcmd->nleft = memout.nextc - memout.buf;
1021                         memout.buf = NULL;
1022                 }
1023                 if (cmdentry.u.index != EXECCMD)
1024                         popredir();
1025                 if (e != -1) {
1026                         if ((e != EXERROR && e != EXEXEC)
1027                             || cmdentry.special)
1028                                 exraise(e);
1029                         popfilesupto(savetopfile);
1030                         if (flags != EV_BACKCMD)
1031                                 FORCEINTON;
1032                 }
1033         } else {
1034 #ifdef DEBUG
1035                 trputs("normal command:  ");  trargs(argv);
1036 #endif
1037                 redirect(cmd->ncmd.redirect, 0);
1038                 for (sp = varlist.list ; sp ; sp = sp->next)
1039                         setvareq(sp->text, VEXPORT|VSTACK);
1040                 envp = environment();
1041                 shellexec(argv, envp, path, cmdentry.u.index);
1042                 /*NOTREACHED*/
1043         }
1044         goto out;
1045
1046 parent: /* parent process gets here (if we forked) */
1047         if (mode == FORK_FG) {  /* argument to fork */
1048                 INTOFF;
1049                 exitstatus = waitforjob(jp, &realstatus);
1050                 INTON;
1051                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1052                         evalskip = SKIPBREAK;
1053                         skipcount = loopnest;
1054                 }
1055         } else if (mode == FORK_NOJOB) {
1056                 backcmd->fd = pip[0];
1057                 close(pip[1]);
1058                 backcmd->jp = jp;
1059         } else
1060                 exitstatus = 0;
1061
1062 out:
1063         if (lastarg)
1064                 setvar("_", lastarg, 0);
1065         if (do_clearcmdentry)
1066                 clearcmdentry();
1067         popstackmark(&smark);
1068 }
1069
1070
1071
1072 /*
1073  * Search for a command.  This is called before we fork so that the
1074  * location of the command will be available in the parent as well as
1075  * the child.  The check for "goodname" is an overly conservative
1076  * check that the name will not be subject to expansion.
1077  */
1078
1079 static void
1080 prehash(union node *n)
1081 {
1082         struct cmdentry entry;
1083
1084         if (n && n->type == NCMD && n->ncmd.args)
1085                 if (goodname(n->ncmd.args->narg.text))
1086                         find_command(n->ncmd.args->narg.text, &entry, 0,
1087                                      pathval());
1088 }
1089
1090
1091
1092 /*
1093  * Builtin commands.  Builtin commands whose functions are closely
1094  * tied to evaluation are implemented here.
1095  */
1096
1097 /*
1098  * No command given, a bltin command with no arguments, or a bltin command
1099  * with an invalid name.
1100  */
1101
1102 int
1103 bltincmd(int argc, char **argv)
1104 {
1105         if (argc > 1) {
1106                 out2fmt_flush("%s: not found\n", argv[1]);
1107                 return 127;
1108         }
1109         /*
1110          * Preserve exitstatus of a previous possible redirection
1111          * as POSIX mandates
1112          */
1113         return exitstatus;
1114 }
1115
1116
1117 /*
1118  * Handle break and continue commands.  Break, continue, and return are
1119  * all handled by setting the evalskip flag.  The evaluation routines
1120  * above all check this flag, and if it is set they start skipping
1121  * commands rather than executing them.  The variable skipcount is
1122  * the number of loops to break/continue, or the number of function
1123  * levels to return.  (The latter is always 1.)  It should probably
1124  * be an error to break out of more loops than exist, but it isn't
1125  * in the standard shell so we don't make it one here.
1126  */
1127
1128 int
1129 breakcmd(int argc, char **argv)
1130 {
1131         int n = argc > 1 ? number(argv[1]) : 1;
1132
1133         if (n > loopnest)
1134                 n = loopnest;
1135         if (n > 0) {
1136                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1137                 skipcount = n;
1138         }
1139         return 0;
1140 }
1141
1142 /*
1143  * The `command' command.
1144  */
1145 int
1146 commandcmd(int argc, char **argv)
1147 {
1148         const char *path;
1149         int ch;
1150         int cmd = -1;
1151
1152         path = bltinlookup("PATH", 1);
1153
1154         optind = optreset = 1;
1155         opterr = 0;
1156         while ((ch = getopt(argc, argv, "pvV")) != -1) {
1157                 switch (ch) {
1158                 case 'p':
1159                         path = _PATH_STDPATH;
1160                         break;
1161                 case 'v':
1162                         cmd = TYPECMD_SMALLV;
1163                         break;
1164                 case 'V':
1165                         cmd = TYPECMD_BIGV;
1166                         break;
1167                 case '?':
1168                 default:
1169                         error("unknown option: -%c", optopt);
1170                 }
1171         }
1172         argc -= optind;
1173         argv += optind;
1174
1175         if (cmd != -1) {
1176                 if (argc != 1)
1177                         error("wrong number of arguments");
1178                 return typecmd_impl(2, argv - 1, cmd, path);
1179         }
1180         if (argc != 0)
1181                 error("commandcmd bad call");
1182
1183         /*
1184          * Do nothing successfully if no command was specified;
1185          * ksh also does this.
1186          */
1187         return(0);
1188 }
1189
1190
1191 /*
1192  * The return command.
1193  */
1194
1195 int
1196 returncmd(int argc, char **argv)
1197 {
1198         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1199
1200         if (funcnest) {
1201                 evalskip = SKIPFUNC;
1202                 skipcount = 1;
1203         } else {
1204                 /* skip the rest of the file */
1205                 evalskip = SKIPFILE;
1206                 skipcount = 1;
1207         }
1208         return ret;
1209 }
1210
1211
1212 int
1213 falsecmd(int argc __unused, char **argv __unused)
1214 {
1215         return 1;
1216 }
1217
1218
1219 int
1220 truecmd(int argc __unused, char **argv __unused)
1221 {
1222         return 0;
1223 }
1224
1225
1226 int
1227 execcmd(int argc, char **argv)
1228 {
1229         /*
1230          * Because we have historically not supported any options,
1231          * only treat "--" specially.
1232          */
1233         if (argc > 1 && strcmp(argv[1], "--") == 0)
1234                 argc--, argv++;
1235         if (argc > 1) {
1236                 struct strlist *sp;
1237
1238                 iflag = 0;              /* exit on error */
1239                 mflag = 0;
1240                 optschanged();
1241                 for (sp = cmdenviron; sp ; sp = sp->next)
1242                         setvareq(sp->text, VEXPORT|VSTACK);
1243                 shellexec(argv + 1, environment(), pathval(), 0);
1244
1245         }
1246         return 0;
1247 }
1248
1249
1250 int
1251 timescmd(int argc __unused, char **argv __unused)
1252 {
1253         struct rusage ru;
1254         long shumins, shsmins, chumins, chsmins;
1255         double shusecs, shssecs, chusecs, chssecs;
1256
1257         if (getrusage(RUSAGE_SELF, &ru) < 0)
1258                 return 1;
1259         shumins = ru.ru_utime.tv_sec / 60;
1260         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1261         shsmins = ru.ru_stime.tv_sec / 60;
1262         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1263         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1264                 return 1;
1265         chumins = ru.ru_utime.tv_sec / 60;
1266         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1267         chsmins = ru.ru_stime.tv_sec / 60;
1268         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1269         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1270             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1271         return 0;
1272 }