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 1.103 2011/04/25 20:54:12 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                 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                 close(pip[1]);
 558         }
 559         INTON;
 560         if (n->npipe.backgnd == 0) {
 561                 INTOFF;
 562                 exitstatus = waitforjob(jp, NULL);
 563                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 564                 INTON;
 565         } else
 566                 exitstatus = 0;
 567 }
 568
 569
 570
 571 static int
 572 is_valid_fast_cmdsubst(union node *n)
 573 {
 574         union node *argp;
 575
 576         if (n->type != NCMD)
 577                 return 0;
 578         for (argp = n->ncmd.args ; argp ; argp = argp->narg.next)
 579                 if (expandhassideeffects(argp->narg.text))
 580                         return 0;
 581         return 1;
 582 }
 583
 584 /*
 585  * Execute a command inside back quotes.  If it's a builtin command, we
 586  * want to save its output in a block obtained from malloc.  Otherwise
 587  * we fork off a subprocess and get the output of the command via a pipe.
 588  * Should be called with interrupts off.
 589  */
 590
 591 void
 592 evalbackcmd(union node *n, struct backcmd *result)
 593 {
 594         int pip[2];
 595         struct job *jp;
 596         struct stackmark smark;         /* unnecessary */
 597         struct jmploc jmploc;
 598         struct jmploc *savehandler;
 599
 600         setstackmark(&smark);
 601         result->fd = -1;
 602         result->buf = NULL;
 603         result->nleft = 0;
 604         result->jp = NULL;
 605         if (n == NULL) {
 606                 exitstatus = 0;
 607                 goto out;
 608         }
 609         if (is_valid_fast_cmdsubst(n)) {
 610                 exitstatus = oexitstatus;
 611                 savehandler = handler;
 612                 if (setjmp(jmploc.loc)) {
 613                         if (exception == EXERROR || exception == EXEXEC)
 614                                 exitstatus = 2;
 615                         else if (exception != 0) {
 616                                 handler = savehandler;
 617                                 longjmp(handler->loc, 1);
 618                         }
 619                 } else {
 620                         handler = &jmploc;
 621                         evalcommand(n, EV_BACKCMD, result);
 622                 }
 623                 handler = savehandler;
 624         } else {
 625                 exitstatus = 0;
 626                 if (pipe(pip) < 0)
 627                         error("Pipe call failed: %s", strerror(errno));
 628                 jp = makejob(n, 1);
 629                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 630                         FORCEINTON;
 631                         close(pip[0]);
 632                         if (pip[1] != 1) {
 633                                 dup2(pip[1], 1);
 634                                 close(pip[1]);
 635                         }
 636                         evaltree(n, EV_EXIT);
 637                 }
 638                 close(pip[1]);
 639                 result->fd = pip[0];
 640                 result->jp = jp;
 641         }
 642 out:
 643         popstackmark(&smark);
 644         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 645                 result->fd, result->buf, result->nleft, result->jp));
 646 }
 647
 648 /*
 649  * Check if a builtin can safely be executed in the same process,
 650  * even though it should be in a subshell (command substitution).
 651  * Note that jobid, jobs, times and trap can show information not
 652  * available in a child process; this is deliberate.
 653  * The arguments should already have been expanded.
 654  */
 655 static int
 656 safe_builtin(int idx, int argc, char **argv)
 657 {
 658         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
 659             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
 660             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
 661             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
 662             idx == TYPECMD)
 663                 return (1);
 664         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 665             idx == UMASKCMD)
 666                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 667         if (idx == SETCMD)
 668                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 669                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 670                     argv[1][2] == '\0'));
 671         return (0);
 672 }
 673
 674 /*
 675  * Execute a simple command.
 676  * Note: This may or may not return if (flags & EV_EXIT).
 677  */
 678
 679 static void
 680 evalcommand(union node *cmd, int flgs, struct backcmd *backcmd)
 681 {
 682         struct stackmark smark;
 683         union node *argp;
 684         struct arglist arglist;
 685         struct arglist varlist;
 686         volatile int flags = flgs;
 687         char **volatile argv;
 688         volatile int argc;
 689         char **envp;
 690         int varflag;
 691         struct strlist *sp;
 692         int mode;
 693         int pip[2];
 694         struct cmdentry cmdentry;
 695         struct job *volatile jp;
 696         struct jmploc jmploc;
 697         struct jmploc *savehandler;
 698         const char *savecmdname;
 699         struct shparam saveparam;
 700         struct localvar *savelocalvars;
 701         struct parsefile *savetopfile;
 702         volatile int e;
 703         char *volatile lastarg;
 704         int realstatus;
 705         volatile int do_clearcmdentry;
 706         const char *path = pathval();
 707
 708         /* First expand the arguments. */
 709         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 710         setstackmark(&smark);
 711         arglist.lastp = &arglist.list;
 712         varlist.lastp = &varlist.list;
 713         varflag = 1;
 714         jp = NULL;
 715         do_clearcmdentry = 0;
 716         oexitstatus = exitstatus;
 717         exitstatus = 0;
 718         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 719                 char *p = argp->narg.text;
 720                 if (varflag && is_name(*p)) {
 721                         do {
 722                                 p++;
 723                         } while (is_in_name(*p));
 724                         if (*p == '=') {
 725                                 expandarg(argp, &varlist, EXP_VARTILDE);
 726                                 continue;
 727                         }
 728                 }
 729                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 730                 varflag = 0;
 731         }
 732         *arglist.lastp = NULL;
 733         *varlist.lastp = NULL;
 734         expredir(cmd->ncmd.redirect);
 735         argc = 0;
 736         for (sp = arglist.list ; sp ; sp = sp->next)
 737                 argc++;
 738         /* Add one slot at the beginning for tryexec(). */
 739         argv = stalloc(sizeof (char *) * (argc + 2));
 740         argv++;
 741
 742         for (sp = arglist.list ; sp ; sp = sp->next) {
 743                 TRACE(("evalcommand arg: %s\n", sp->text));
 744                 *argv++ = sp->text;
 745         }
 746         *argv = NULL;
 747         lastarg = NULL;
 748         if (iflag && funcnest == 0 && argc > 0)
 749                 lastarg = argv[-1];
 750         argv -= argc;
 751
 752         /* Print the command if xflag is set. */
 753         if (xflag) {
 754                 char sep = 0;
 755                 const char *p;
 756                 out2str(ps4val());
 757                 for (sp = varlist.list ; sp ; sp = sp->next) {
 758                         if (sep != 0)
 759                                 out2c(' ');
 760                         p = strchr(sp->text, '=');
 761                         if (p != NULL) {
 762                                 p++;
 763                                 outbin(sp->text, p - sp->text, out2);
 764                                 out2qstr(p);
 765                         } else
 766                                 out2qstr(sp->text);
 767                         sep = ' ';
 768                 }
 769                 for (sp = arglist.list ; sp ; sp = sp->next) {
 770                         if (sep != 0)
 771                                 out2c(' ');
 772                         /* Disambiguate command looking like assignment. */
 773                         if (sp == arglist.list &&
 774                                         strchr(sp->text, '=') != NULL &&
 775                                         strchr(sp->text, '\'') == NULL) {
 776                                 out2c('\'');
 777                                 out2str(sp->text);
 778                                 out2c('\'');
 779                         } else
 780                                 out2qstr(sp->text);
 781                         sep = ' ';
 782                 }
 783                 out2c('\n');
 784                 flushout(&errout);
 785         }
 786
 787         /* Now locate the command. */
 788         if (argc == 0) {
 789                 /* Variable assignment(s) without command */
 790                 cmdentry.cmdtype = CMDBUILTIN;
 791                 cmdentry.u.index = BLTINCMD;
 792                 cmdentry.special = 0;
 793         } else {
 794                 static const char PATH[] = "PATH=";
 795                 int cmd_flags = 0, bltinonly = 0;
 796
 797                 /*
 798                  * Modify the command lookup path, if a PATH= assignment
 799                  * is present
 800                  */
 801                 for (sp = varlist.list ; sp ; sp = sp->next)
 802                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 803                                 path = sp->text + sizeof(PATH) - 1;
 804                                 /*
 805                                  * On `PATH=... command`, we need to make
 806                                  * sure that the command isn't using the
 807                                  * non-updated hash table of the outer PATH
 808                                  * setting and we need to make sure that
 809                                  * the hash table isn't filled with items
 810                                  * from the temporary setting.
 811                                  *
 812                                  * It would be better to forbit using and
 813                                  * updating the table while this command
 814                                  * runs, by the command finding mechanism
 815                                  * is heavily integrated with hash handling,
 816                                  * so we just delete the hash before and after
 817                                  * the command runs. Partly deleting like
 818                                  * changepatch() does doesn't seem worth the
 819                                  * bookinging effort, since most such runs add
 820                                  * directories in front of the new PATH.
 821                                  */
 822                                 clearcmdentry();
 823                                 do_clearcmdentry = 1;
 824                         }
 825
 826                 for (;;) {
 827                         if (bltinonly) {
 828                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 829                                 if (cmdentry.u.index < 0) {
 830                                         cmdentry.u.index = BLTINCMD;
 831                                         argv--;
 832                                         argc++;
 833                                         break;
 834                                 }
 835                         } else
 836                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 837                         /* implement the bltin and command builtins here */
 838                         if (cmdentry.cmdtype != CMDBUILTIN)
 839                                 break;
 840                         if (cmdentry.u.index == BLTINCMD) {
 841                                 if (argc == 1)
 842                                         break;
 843                                 argv++;
 844                                 argc--;
 845                                 bltinonly = 1;
 846                         } else if (cmdentry.u.index == COMMANDCMD) {
 847                                 if (argc == 1)
 848                                         break;
 849                                 if (!strcmp(argv[1], "-p")) {
 850                                         if (argc == 2)
 851                                                 break;
 852                                         if (argv[2][0] == '-') {
 853                                                 if (strcmp(argv[2], "--"))
 854                                                         break;
 855                                                 if (argc == 3)
 856                                                         break;
 857                                                 argv += 3;
 858                                                 argc -= 3;
 859                                         } else {
 860                                                 argv += 2;
 861                                                 argc -= 2;
 862                                         }
 863                                         path = _PATH_STDPATH;
 864                                         clearcmdentry();
 865                                         do_clearcmdentry = 1;
 866                                 } else if (!strcmp(argv[1], "--")) {
 867                                         if (argc == 2)
 868                                                 break;
 869                                         argv += 2;
 870                                         argc -= 2;
 871                                 } else if (argv[1][0] == '-')
 872                                         break;
 873                                 else {
 874                                         argv++;
 875                                         argc--;
 876                                 }
 877                                 cmd_flags |= DO_NOFUNC;
 878                                 bltinonly = 0;
 879                         } else
 880                                 break;
 881                 }
 882                 /*
 883                  * Special builtins lose their special properties when
 884                  * called via 'command'.
 885                  */
 886                 if (cmd_flags & DO_NOFUNC)
 887                         cmdentry.special = 0;
 888         }
 889
 890         /* Fork off a child process if necessary. */
 891         if (cmd->ncmd.backgnd
 892          || ((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 893             && ((flags & EV_EXIT) == 0 || have_traps()))
 894          || ((flags & EV_BACKCMD) != 0
 895             && (cmdentry.cmdtype != CMDBUILTIN ||
 896                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 897                 jp = makejob(cmd, 1);
 898                 mode = cmd->ncmd.backgnd;
 899                 if (flags & EV_BACKCMD) {
 900                         mode = FORK_NOJOB;
 901                         if (pipe(pip) < 0)
 902                                 error("Pipe call failed: %s", strerror(errno));
 903                 }
 904                 if (forkshell(jp, cmd, mode) != 0)
 905                         goto parent;    /* at end of routine */
 906                 if (flags & EV_BACKCMD) {
 907                         FORCEINTON;
 908                         close(pip[0]);
 909                         if (pip[1] != 1) {
 910                                 dup2(pip[1], 1);
 911                                 close(pip[1]);
 912                         }
 913                 }
 914                 flags |= EV_EXIT;
 915         }
 916
 917         /* This is the child process if a fork occurred. */
 918         /* Execute the command. */
 919         if (cmdentry.cmdtype == CMDFUNCTION) {
 920 #ifdef DEBUG
 921                 trputs("Shell function:  ");  trargs(argv);
 922 #endif
 923                 saveparam = shellparam;
 924                 shellparam.malloc = 0;
 925                 shellparam.reset = 1;
 926                 shellparam.nparam = argc - 1;
 927                 shellparam.p = argv + 1;
 928                 shellparam.optnext = NULL;
 929                 INTOFF;
 930                 savelocalvars = localvars;
 931                 localvars = NULL;
 932                 reffunc(cmdentry.u.func);
 933                 savehandler = handler;
 934                 if (setjmp(jmploc.loc)) {
 935                         freeparam(&shellparam);
 936                         shellparam = saveparam;
 937                         popredir();
 938                         unreffunc(cmdentry.u.func);
 939                         poplocalvars();
 940                         localvars = savelocalvars;
 941                         funcnest--;
 942                         handler = savehandler;
 943                         longjmp(handler->loc, 1);
 944                 }
 945                 handler = &jmploc;
 946                 funcnest++;
 947                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
 948                 INTON;
 949                 for (sp = varlist.list ; sp ; sp = sp->next)
 950                         mklocal(sp->text);
 951                 exitstatus = oexitstatus;
 952                 evaltree(getfuncnode(cmdentry.u.func),
 953                     flags & (EV_TESTED | EV_EXIT));
 954                 INTOFF;
 955                 unreffunc(cmdentry.u.func);
 956                 poplocalvars();
 957                 localvars = savelocalvars;
 958                 freeparam(&shellparam);
 959                 shellparam = saveparam;
 960                 handler = savehandler;
 961                 funcnest--;
 962                 popredir();
 963                 INTON;
 964                 if (evalskip == SKIPFUNC) {
 965                         evalskip = 0;
 966                         skipcount = 0;
 967                 }
 968                 if (jp)
 969                         exitshell(exitstatus);
 970         } else if (cmdentry.cmdtype == CMDBUILTIN) {
 971 #ifdef DEBUG
 972                 trputs("builtin command:  ");  trargs(argv);
 973 #endif
 974                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
 975                 if (flags == EV_BACKCMD) {
 976                         memout.nleft = 0;
 977                         memout.nextc = memout.buf;
 978                         memout.bufsize = 64;
 979                         mode |= REDIR_BACKQ;
 980                         cmdentry.special = 0;
 981                 }
 982                 savecmdname = commandname;
 983                 savetopfile = getcurrentfile();
 984                 cmdenviron = varlist.list;
 985                 e = -1;
 986                 savehandler = handler;
 987                 if (setjmp(jmploc.loc)) {
 988                         e = exception;
 989                         if (e == EXINT)
 990                                 exitstatus = SIGINT+128;
 991                         else if (e != EXEXIT)
 992                                 exitstatus = 2;
 993                         goto cmddone;
 994                 }
 995                 handler = &jmploc;
 996                 redirect(cmd->ncmd.redirect, mode);
 997                 /*
 998                  * If there is no command word, redirection errors should
 999                  * not be fatal but assignment errors should.
1000                  */
1001                 if (argc == 0 && !(flags & EV_BACKCMD))
1002                         cmdentry.special = 1;
1003                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1004                 if (argc > 0)
1005                         bltinsetlocale();
1006                 commandname = argv[0];
1007                 argptr = argv + 1;
1008                 nextopt_optptr = NULL;          /* initialize nextopt */
1009                 builtin_flags = flags;
1010                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1011                 flushall();
1012 cmddone:
1013                 if (argc > 0)
1014                         bltinunsetlocale();
1015                 cmdenviron = NULL;
1016                 out1 = &output;
1017                 out2 = &errout;
1018                 freestdout();
1019                 handler = savehandler;
1020                 commandname = savecmdname;
1021                 if (jp)
1022                         exitshell(exitstatus);
1023                 if (flags == EV_BACKCMD) {
1024                         backcmd->buf = memout.buf;
1025                         backcmd->nleft = memout.nextc - memout.buf;
1026                         memout.buf = NULL;
1027                 }
1028                 if (cmdentry.u.index != EXECCMD)
1029                         popredir();
1030                 if (e != -1) {
1031                         if ((e != EXERROR && e != EXEXEC)
1032                             || cmdentry.special)
1033                                 exraise(e);
1034                         popfilesupto(savetopfile);
1035                         if (flags != EV_BACKCMD)
1036                                 FORCEINTON;
1037                 }
1038         } else {
1039 #ifdef DEBUG
1040                 trputs("normal command:  ");  trargs(argv);
1041 #endif
1042                 redirect(cmd->ncmd.redirect, 0);
1043                 for (sp = varlist.list ; sp ; sp = sp->next)
1044                         setvareq(sp->text, VEXPORT|VSTACK);
1045                 envp = environment();
1046                 shellexec(argv, envp, path, cmdentry.u.index);
1047                 /*NOTREACHED*/
1048         }
1049         goto out;
1050
1051 parent: /* parent process gets here (if we forked) */
1052         if (mode == FORK_FG) {  /* argument to fork */
1053                 INTOFF;
1054                 exitstatus = waitforjob(jp, &realstatus);
1055                 INTON;
1056                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1057                         evalskip = SKIPBREAK;
1058                         skipcount = loopnest;
1059                 }
1060         } else if (mode == FORK_NOJOB) {
1061                 backcmd->fd = pip[0];
1062                 close(pip[1]);
1063                 backcmd->jp = jp;
1064         } else
1065                 exitstatus = 0;
1066
1067 out:
1068         if (lastarg)
1069                 setvar("_", lastarg, 0);
1070         if (do_clearcmdentry)
1071                 clearcmdentry();
1072         popstackmark(&smark);
1073 }
1074
1075
1076
1077 /*
1078  * Search for a command.  This is called before we fork so that the
1079  * location of the command will be available in the parent as well as
1080  * the child.  The check for "goodname" is an overly conservative
1081  * check that the name will not be subject to expansion.
1082  */
1083
1084 static void
1085 prehash(union node *n)
1086 {
1087         struct cmdentry entry;
1088
1089         if (n && n->type == NCMD && n->ncmd.args)
1090                 if (goodname(n->ncmd.args->narg.text))
1091                         find_command(n->ncmd.args->narg.text, &entry, 0,
1092                                      pathval());
1093 }
1094
1095
1096
1097 /*
1098  * Builtin commands.  Builtin commands whose functions are closely
1099  * tied to evaluation are implemented here.
1100  */
1101
1102 /*
1103  * No command given, a bltin command with no arguments, or a bltin command
1104  * with an invalid name.
1105  */
1106
1107 int
1108 bltincmd(int argc, char **argv)
1109 {
1110         if (argc > 1) {
1111                 out2fmt_flush("%s: not found\n", argv[1]);
1112                 return 127;
1113         }
1114         /*
1115          * Preserve exitstatus of a previous possible redirection
1116          * as POSIX mandates
1117          */
1118         return exitstatus;
1119 }
1120
1121
1122 /*
1123  * Handle break and continue commands.  Break, continue, and return are
1124  * all handled by setting the evalskip flag.  The evaluation routines
1125  * above all check this flag, and if it is set they start skipping
1126  * commands rather than executing them.  The variable skipcount is
1127  * the number of loops to break/continue, or the number of function
1128  * levels to return.  (The latter is always 1.)  It should probably
1129  * be an error to break out of more loops than exist, but it isn't
1130  * in the standard shell so we don't make it one here.
1131  */
1132
1133 int
1134 breakcmd(int argc, char **argv)
1135 {
1136         int n = argc > 1 ? number(argv[1]) : 1;
1137
1138         if (n > loopnest)
1139                 n = loopnest;
1140         if (n > 0) {
1141                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1142                 skipcount = n;
1143         }
1144         return 0;
1145 }
1146
1147 /*
1148  * The `command' command.
1149  */
1150 int
1151 commandcmd(int argc, char **argv)
1152 {
1153         const char *path;
1154         int ch;
1155         int cmd = -1;
1156
1157         path = bltinlookup("PATH", 1);
1158
1159         optind = optreset = 1;
1160         opterr = 0;
1161         while ((ch = getopt(argc, argv, "pvV")) != -1) {
1162                 switch (ch) {
1163                 case 'p':
1164                         path = _PATH_STDPATH;
1165                         break;
1166                 case 'v':
1167                         cmd = TYPECMD_SMALLV;
1168                         break;
1169                 case 'V':
1170                         cmd = TYPECMD_BIGV;
1171                         break;
1172                 case '?':
1173                 default:
1174                         error("unknown option: -%c", optopt);
1175                 }
1176         }
1177         argc -= optind;
1178         argv += optind;
1179
1180         if (cmd != -1) {
1181                 if (argc != 1)
1182                         error("wrong number of arguments");
1183                 return typecmd_impl(2, argv - 1, cmd, path);
1184         }
1185         if (argc != 0)
1186                 error("commandcmd bad call");
1187
1188         /*
1189          * Do nothing successfully if no command was specified;
1190          * ksh also does this.
1191          */
1192         return(0);
1193 }
1194
1195
1196 /*
1197  * The return command.
1198  */
1199
1200 int
1201 returncmd(int argc, char **argv)
1202 {
1203         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1204
1205         if (funcnest) {
1206                 evalskip = SKIPFUNC;
1207                 skipcount = 1;
1208         } else {
1209                 /* skip the rest of the file */
1210                 evalskip = SKIPFILE;
1211                 skipcount = 1;
1212         }
1213         return ret;
1214 }
1215
1216
1217 int
1218 falsecmd(int argc __unused, char **argv __unused)
1219 {
1220         return 1;
1221 }
1222
1223
1224 int
1225 truecmd(int argc __unused, char **argv __unused)
1226 {
1227         return 0;
1228 }
1229
1230
1231 int
1232 execcmd(int argc, char **argv)
1233 {
1234         /*
1235          * Because we have historically not supported any options,
1236          * only treat "--" specially.
1237          */
1238         if (argc > 1 && strcmp(argv[1], "--") == 0)
1239                 argc--, argv++;
1240         if (argc > 1) {
1241                 struct strlist *sp;
1242
1243                 iflag = 0;              /* exit on error */
1244                 mflag = 0;
1245                 optschanged();
1246                 for (sp = cmdenviron; sp ; sp = sp->next)
1247                         setvareq(sp->text, VEXPORT|VSTACK);
1248                 shellexec(argv + 1, environment(), pathval(), 0);
1249
1250         }
1251         return 0;
1252 }
1253
1254
1255 int
1256 timescmd(int argc __unused, char **argv __unused)
1257 {
1258         struct rusage ru;
1259         long shumins, shsmins, chumins, chsmins;
1260         double shusecs, shssecs, chusecs, chssecs;
1261
1262         if (getrusage(RUSAGE_SELF, &ru) < 0)
1263                 return 1;
1264         shumins = ru.ru_utime.tv_sec / 60;
1265         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1266         shsmins = ru.ru_stime.tv_sec / 60;
1267         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1268         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1269                 return 1;
1270         chumins = ru.ru_utime.tv_sec / 60;
1271         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1272         chsmins = ru.ru_stime.tv_sec / 60;
1273         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1274         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1275             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1276         return 0;
1277 }