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 1.120 2012/02/04 23:12:14 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 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 union node *evalcase(union node *);
  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);
 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                         next = evalcase(n);
 261                         break;
 262                 case NCLIST:
 263                         next = n->nclist.body;
 264                         break;
 265                 case NCLISTFALLTHRU:
 266                         if (n->nclist.body) {
 267                                 evaltree(n->nclist.body, flags & ~EV_EXIT);
 268                                 if (evalskip)
 269                                         goto out;
 270                         }
 271                         next = n->nclist.next;
 272                         break;
 273                 case NDEFUN:
 274                         defun(n->narg.text, n->narg.next);
 275                         exitstatus = 0;
 276                         break;
 277                 case NNOT:
 278                         evaltree(n->nnot.com, EV_TESTED);
 279                         exitstatus = !exitstatus;
 280                         break;
 281
 282                 case NPIPE:
 283                         evalpipe(n);
 284                         do_etest = !(flags & EV_TESTED);
 285                         break;
 286                 case NCMD:
 287                         evalcommand(n, flags, NULL);
 288                         do_etest = !(flags & EV_TESTED);
 289                         break;
 290                 default:
 291                         out1fmt("Node type = %d\n", n->type);
 292                         flushout(&output);
 293                         break;
 294                 }
 295                 n = next;
 296         } while (n != NULL);
 297 out:
 298         if (pendingsigs)
 299                 dotrap();
 300         if (eflag && exitstatus != 0 && do_etest)
 301                 exitshell(exitstatus);
 302         if (flags & EV_EXIT)
 303                 exraise(EXEXIT);
 304 }
 305
 306
 307 static void
 308 evalloop(union node *n, int flags)
 309 {
 310         int status;
 311
 312         loopnest++;
 313         status = 0;
 314         for (;;) {
 315                 evaltree(n->nbinary.ch1, EV_TESTED);
 316                 if (evalskip) {
 317 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
 318                                 evalskip = 0;
 319                                 continue;
 320                         }
 321                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 322                                 evalskip = 0;
 323                         if (evalskip == SKIPFUNC || evalskip == SKIPFILE)
 324                                 status = exitstatus;
 325                         break;
 326                 }
 327                 if (n->type == NWHILE) {
 328                         if (exitstatus != 0)
 329                                 break;
 330                 } else {
 331                         if (exitstatus == 0)
 332                                 break;
 333                 }
 334                 evaltree(n->nbinary.ch2, flags);
 335                 status = exitstatus;
 336                 if (evalskip)
 337                         goto skipping;
 338         }
 339         loopnest--;
 340         exitstatus = status;
 341 }
 342
 343
 344
 345 static void
 346 evalfor(union node *n, int flags)
 347 {
 348         struct arglist arglist;
 349         union node *argp;
 350         struct strlist *sp;
 351         struct stackmark smark;
 352         int status;
 353
 354         setstackmark(&smark);
 355         arglist.lastp = &arglist.list;
 356         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 357                 oexitstatus = exitstatus;
 358                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 359         }
 360         *arglist.lastp = NULL;
 361
 362         loopnest++;
 363         status = 0;
 364         for (sp = arglist.list ; sp ; sp = sp->next) {
 365                 setvar(n->nfor.var, sp->text, 0);
 366                 evaltree(n->nfor.body, flags);
 367                 status = exitstatus;
 368                 if (evalskip) {
 369                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 370                                 evalskip = 0;
 371                                 continue;
 372                         }
 373                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 374                                 evalskip = 0;
 375                         break;
 376                 }
 377         }
 378         loopnest--;
 379         popstackmark(&smark);
 380         exitstatus = status;
 381 }
 382
 383
 384 /*
 385  * Evaluate a case statement, returning the selected tree.
 386  *
 387  * The exit status needs care to get right.
 388  */
 389
 390 static union node *
 391 evalcase(union node *n)
 392 {
 393         union node *cp;
 394         union node *patp;
 395         struct arglist arglist;
 396         struct stackmark smark;
 397
 398         setstackmark(&smark);
 399         arglist.lastp = &arglist.list;
 400         oexitstatus = exitstatus;
 401         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 402         for (cp = n->ncase.cases ; cp ; cp = cp->nclist.next) {
 403                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 404                         if (casematch(patp, arglist.list->text)) {
 405                                 popstackmark(&smark);
 406                                 while (cp->nclist.next &&
 407                                     cp->type == NCLISTFALLTHRU &&
 408                                     cp->nclist.body == NULL)
 409                                         cp = cp->nclist.next;
 410                                 if (cp->nclist.next &&
 411                                     cp->type == NCLISTFALLTHRU)
 412                                         return (cp);
 413                                 if (cp->nclist.body == NULL)
 414                                         exitstatus = 0;
 415                                 return (cp->nclist.body);
 416                         }
 417                 }
 418         }
 419         popstackmark(&smark);
 420         exitstatus = 0;
 421         return (NULL);
 422 }
 423
 424
 425
 426 /*
 427  * Kick off a subshell to evaluate a tree.
 428  */
 429
 430 static void
 431 evalsubshell(union node *n, int flags)
 432 {
 433         struct job *jp;
 434         int backgnd = (n->type == NBACKGND);
 435
 436         oexitstatus = exitstatus;
 437         expredir(n->nredir.redirect);
 438         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
 439             forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
 440                 if (backgnd)
 441                         flags &=~ EV_TESTED;
 442                 redirect(n->nredir.redirect, 0);
 443                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 444         } else if (!backgnd) {
 445                 INTOFF;
 446                 exitstatus = waitforjob(jp, NULL);
 447                 INTON;
 448         } else
 449                 exitstatus = 0;
 450 }
 451
 452
 453 /*
 454  * Evaluate a redirected compound command.
 455  */
 456
 457 static void
 458 evalredir(union node *n, int flags)
 459 {
 460         struct jmploc jmploc;
 461         struct jmploc *savehandler;
 462         volatile int in_redirect = 1;
 463
 464         oexitstatus = exitstatus;
 465         expredir(n->nredir.redirect);
 466         savehandler = handler;
 467         if (setjmp(jmploc.loc)) {
 468                 int e;
 469
 470                 handler = savehandler;
 471                 e = exception;
 472                 popredir();
 473                 if (e == EXERROR || e == EXEXEC) {
 474                         if (in_redirect) {
 475                                 exitstatus = 2;
 476                                 return;
 477                         }
 478                 }
 479                 longjmp(handler->loc, 1);
 480         } else {
 481                 INTOFF;
 482                 handler = &jmploc;
 483                 redirect(n->nredir.redirect, REDIR_PUSH);
 484                 in_redirect = 0;
 485                 INTON;
 486                 evaltree(n->nredir.n, flags);
 487         }
 488         INTOFF;
 489         handler = savehandler;
 490         popredir();
 491         INTON;
 492 }
 493
 494
 495 /*
 496  * Compute the names of the files in a redirection list.
 497  */
 498
 499 static void
 500 expredir(union node *n)
 501 {
 502         union node *redir;
 503
 504         for (redir = n ; redir ; redir = redir->nfile.next) {
 505                 struct arglist fn;
 506                 fn.lastp = &fn.list;
 507                 switch (redir->type) {
 508                 case NFROM:
 509                 case NTO:
 510                 case NFROMTO:
 511                 case NAPPEND:
 512                 case NCLOBBER:
 513                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 514                         redir->nfile.expfname = fn.list->text;
 515                         break;
 516                 case NFROMFD:
 517                 case NTOFD:
 518                         if (redir->ndup.vname) {
 519                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
 520                                 fixredir(redir, fn.list->text, 1);
 521                         }
 522                         break;
 523                 }
 524         }
 525 }
 526
 527
 528
 529 /*
 530  * Evaluate a pipeline.  All the processes in the pipeline are children
 531  * of the process creating the pipeline.  (This differs from some versions
 532  * of the shell, which make the last process in a pipeline the parent
 533  * of all the rest.)
 534  */
 535
 536 static void
 537 evalpipe(union node *n)
 538 {
 539         struct job *jp;
 540         struct nodelist *lp;
 541         int pipelen;
 542         int prevfd;
 543         int pip[2];
 544
 545         TRACE(("evalpipe(%p) called\n", (void *)n));
 546         pipelen = 0;
 547         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
 548                 pipelen++;
 549         INTOFF;
 550         jp = makejob(n, pipelen);
 551         prevfd = -1;
 552         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
 553                 prehash(lp->n);
 554                 pip[1] = -1;
 555                 if (lp->next) {
 556                         if (pipe(pip) < 0) {
 557                                 if (prevfd >= 0)
 558                                         close(prevfd);
 559                                 error("Pipe call failed: %s", strerror(errno));
 560                         }
 561                 }
 562                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
 563                         INTON;
 564                         if (prevfd > 0) {
 565                                 dup2(prevfd, 0);
 566                                 close(prevfd);
 567                         }
 568                         if (pip[1] >= 0) {
 569                                 if (!(prevfd >= 0 && pip[0] == 0))
 570                                         close(pip[0]);
 571                                 if (pip[1] != 1) {
 572                                         dup2(pip[1], 1);
 573                                         close(pip[1]);
 574                                 }
 575                         }
 576                         evaltree(lp->n, EV_EXIT);
 577                 }
 578                 if (prevfd >= 0)
 579                         close(prevfd);
 580                 prevfd = pip[0];
 581                 if (pip[1] != -1)
 582                         close(pip[1]);
 583         }
 584         INTON;
 585         if (n->npipe.backgnd == 0) {
 586                 INTOFF;
 587                 exitstatus = waitforjob(jp, NULL);
 588                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 589                 INTON;
 590         } else
 591                 exitstatus = 0;
 592 }
 593
 594
 595
 596 static int
 597 is_valid_fast_cmdsubst(union node *n)
 598 {
 599
 600         return (n->type == NCMD);
 601 }
 602
 603 /*
 604  * Execute a command inside back quotes.  If it's a builtin command, we
 605  * want to save its output in a block obtained from malloc.  Otherwise
 606  * we fork off a subprocess and get the output of the command via a pipe.
 607  * Should be called with interrupts off.
 608  */
 609
 610 void
 611 evalbackcmd(union node *n, struct backcmd *result)
 612 {
 613         int pip[2];
 614         struct job *jp;
 615         struct stackmark smark;         /* unnecessary */
 616         struct jmploc jmploc;
 617         struct jmploc *savehandler;
 618         struct localvar *savelocalvars;
 619
 620         setstackmark(&smark);
 621         result->fd = -1;
 622         result->buf = NULL;
 623         result->nleft = 0;
 624         result->jp = NULL;
 625         if (n == NULL) {
 626                 exitstatus = 0;
 627                 goto out;
 628         }
 629         if (is_valid_fast_cmdsubst(n)) {
 630                 exitstatus = oexitstatus;
 631                 savelocalvars = localvars;
 632                 localvars = NULL;
 633                 forcelocal++;
 634                 savehandler = handler;
 635                 if (setjmp(jmploc.loc)) {
 636                         if (exception == EXERROR || exception == EXEXEC)
 637                                 exitstatus = 2;
 638                         else if (exception != 0) {
 639                                 handler = savehandler;
 640                                 forcelocal--;
 641                                 poplocalvars();
 642                                 localvars = savelocalvars;
 643                                 longjmp(handler->loc, 1);
 644                         }
 645                 } else {
 646                         handler = &jmploc;
 647                         evalcommand(n, EV_BACKCMD, result);
 648                 }
 649                 handler = savehandler;
 650                 forcelocal--;
 651                 poplocalvars();
 652                 localvars = savelocalvars;
 653         } else {
 654                 exitstatus = 0;
 655                 if (pipe(pip) < 0)
 656                         error("Pipe call failed: %s", strerror(errno));
 657                 jp = makejob(n, 1);
 658                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 659                         FORCEINTON;
 660                         close(pip[0]);
 661                         if (pip[1] != 1) {
 662                                 dup2(pip[1], 1);
 663                                 close(pip[1]);
 664                         }
 665                         evaltree(n, EV_EXIT);
 666                 }
 667                 close(pip[1]);
 668                 result->fd = pip[0];
 669                 result->jp = jp;
 670         }
 671 out:
 672         popstackmark(&smark);
 673         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 674                 result->fd, result->buf, result->nleft, result->jp));
 675 }
 676
 677 /*
 678  * Check if a builtin can safely be executed in the same process,
 679  * even though it should be in a subshell (command substitution).
 680  * Note that jobid, jobs, times and trap can show information not
 681  * available in a child process; this is deliberate.
 682  * The arguments should already have been expanded.
 683  */
 684 static int
 685 safe_builtin(int idx, int argc, char **argv)
 686 {
 687         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
 688             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
 689             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
 690             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
 691             idx == TYPECMD)
 692                 return (1);
 693         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 694             idx == UMASKCMD)
 695                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 696         if (idx == SETCMD)
 697                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 698                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 699                     argv[1][2] == '\0'));
 700         return (0);
 701 }
 702
 703 /*
 704  * Execute a simple command.
 705  * Note: This may or may not return if (flags & EV_EXIT).
 706  */
 707
 708 static void
 709 evalcommand(union node *cmd, int flgs, struct backcmd *backcmd)
 710 {
 711         struct stackmark smark;
 712         union node *argp;
 713         struct arglist arglist;
 714         struct arglist varlist;
 715         volatile int flags = flgs;
 716         char **volatile argv;
 717         volatile int argc;
 718         char **envp;
 719         int varflag;
 720         struct strlist *sp;
 721         int mode;
 722         int pip[2];
 723         struct cmdentry cmdentry;
 724         struct job *volatile jp;
 725         struct jmploc jmploc;
 726         struct jmploc *savehandler;
 727         const char *savecmdname;
 728         struct shparam saveparam;
 729         struct localvar *savelocalvars;
 730         struct parsefile *savetopfile;
 731         volatile int e;
 732         char *volatile lastarg;
 733         int realstatus;
 734         volatile int do_clearcmdentry;
 735         const char *path = pathval();
 736
 737         /* First expand the arguments. */
 738         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 739         setstackmark(&smark);
 740         arglist.lastp = &arglist.list;
 741         varlist.lastp = &varlist.list;
 742         varflag = 1;
 743         jp = NULL;
 744         do_clearcmdentry = 0;
 745         oexitstatus = exitstatus;
 746         exitstatus = 0;
 747         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 748                 if (varflag && isassignment(argp->narg.text)) {
 749                         expandarg(argp, &varlist, EXP_VARTILDE);
 750                         continue;
 751                 }
 752                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 753                 varflag = 0;
 754         }
 755         *arglist.lastp = NULL;
 756         *varlist.lastp = NULL;
 757         expredir(cmd->ncmd.redirect);
 758         argc = 0;
 759         for (sp = arglist.list ; sp ; sp = sp->next)
 760                 argc++;
 761         /* Add one slot at the beginning for tryexec(). */
 762         argv = stalloc(sizeof (char *) * (argc + 2));
 763         argv++;
 764
 765         for (sp = arglist.list ; sp ; sp = sp->next) {
 766                 TRACE(("evalcommand arg: %s\n", sp->text));
 767                 *argv++ = sp->text;
 768         }
 769         *argv = NULL;
 770         lastarg = NULL;
 771         if (iflag && funcnest == 0 && argc > 0)
 772                 lastarg = argv[-1];
 773         argv -= argc;
 774
 775         /* Print the command if xflag is set. */
 776         if (xflag) {
 777                 char sep = 0;
 778                 const char *p, *ps4;
 779                 ps4 = expandstr(ps4val());
 780                 out2str(ps4 != NULL ? ps4 : ps4val());
 781                 for (sp = varlist.list ; sp ; sp = sp->next) {
 782                         if (sep != 0)
 783                                 out2c(' ');
 784                         p = strchr(sp->text, '=');
 785                         if (p != NULL) {
 786                                 p++;
 787                                 outbin(sp->text, p - sp->text, out2);
 788                                 out2qstr(p);
 789                         } else
 790                                 out2qstr(sp->text);
 791                         sep = ' ';
 792                 }
 793                 for (sp = arglist.list ; sp ; sp = sp->next) {
 794                         if (sep != 0)
 795                                 out2c(' ');
 796                         /* Disambiguate command looking like assignment. */
 797                         if (sp == arglist.list &&
 798                                         strchr(sp->text, '=') != NULL &&
 799                                         strchr(sp->text, '\'') == NULL) {
 800                                 out2c('\'');
 801                                 out2str(sp->text);
 802                                 out2c('\'');
 803                         } else
 804                                 out2qstr(sp->text);
 805                         sep = ' ';
 806                 }
 807                 out2c('\n');
 808                 flushout(&errout);
 809         }
 810
 811         /* Now locate the command. */
 812         if (argc == 0) {
 813                 /* Variable assignment(s) without command */
 814                 cmdentry.cmdtype = CMDBUILTIN;
 815                 cmdentry.u.index = BLTINCMD;
 816                 cmdentry.special = 0;
 817         } else {
 818                 static const char PATH[] = "PATH=";
 819                 int cmd_flags = 0, bltinonly = 0;
 820
 821                 /*
 822                  * Modify the command lookup path, if a PATH= assignment
 823                  * is present
 824                  */
 825                 for (sp = varlist.list ; sp ; sp = sp->next)
 826                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 827                                 path = sp->text + sizeof(PATH) - 1;
 828                                 /*
 829                                  * On `PATH=... command`, we need to make
 830                                  * sure that the command isn't using the
 831                                  * non-updated hash table of the outer PATH
 832                                  * setting and we need to make sure that
 833                                  * the hash table isn't filled with items
 834                                  * from the temporary setting.
 835                                  *
 836                                  * It would be better to forbit using and
 837                                  * updating the table while this command
 838                                  * runs, by the command finding mechanism
 839                                  * is heavily integrated with hash handling,
 840                                  * so we just delete the hash before and after
 841                                  * the command runs. Partly deleting like
 842                                  * changepatch() does doesn't seem worth the
 843                                  * bookinging effort, since most such runs add
 844                                  * directories in front of the new PATH.
 845                                  */
 846                                 clearcmdentry();
 847                                 do_clearcmdentry = 1;
 848                         }
 849
 850                 for (;;) {
 851                         if (bltinonly) {
 852                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 853                                 if (cmdentry.u.index < 0) {
 854                                         cmdentry.u.index = BLTINCMD;
 855                                         argv--;
 856                                         argc++;
 857                                         break;
 858                                 }
 859                         } else
 860                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 861                         /* implement the bltin and command builtins here */
 862                         if (cmdentry.cmdtype != CMDBUILTIN)
 863                                 break;
 864                         if (cmdentry.u.index == BLTINCMD) {
 865                                 if (argc == 1)
 866                                         break;
 867                                 argv++;
 868                                 argc--;
 869                                 bltinonly = 1;
 870                         } else if (cmdentry.u.index == COMMANDCMD) {
 871                                 if (argc == 1)
 872                                         break;
 873                                 if (!strcmp(argv[1], "-p")) {
 874                                         if (argc == 2)
 875                                                 break;
 876                                         if (argv[2][0] == '-') {
 877                                                 if (strcmp(argv[2], "--"))
 878                                                         break;
 879                                                 if (argc == 3)
 880                                                         break;
 881                                                 argv += 3;
 882                                                 argc -= 3;
 883                                         } else {
 884                                                 argv += 2;
 885                                                 argc -= 2;
 886                                         }
 887                                         path = _PATH_STDPATH;
 888                                         clearcmdentry();
 889                                         do_clearcmdentry = 1;
 890                                 } else if (!strcmp(argv[1], "--")) {
 891                                         if (argc == 2)
 892                                                 break;
 893                                         argv += 2;
 894                                         argc -= 2;
 895                                 } else if (argv[1][0] == '-')
 896                                         break;
 897                                 else {
 898                                         argv++;
 899                                         argc--;
 900                                 }
 901                                 cmd_flags |= DO_NOFUNC;
 902                                 bltinonly = 0;
 903                         } else
 904                                 break;
 905                 }
 906                 /*
 907                  * Special builtins lose their special properties when
 908                  * called via 'command'.
 909                  */
 910                 if (cmd_flags & DO_NOFUNC)
 911                         cmdentry.special = 0;
 912         }
 913
 914         /* Fork off a child process if necessary. */
 915         if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 916             && ((flags & EV_EXIT) == 0 || have_traps()))
 917          || ((flags & EV_BACKCMD) != 0
 918             && (cmdentry.cmdtype != CMDBUILTIN ||
 919                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 920                 jp = makejob(cmd, 1);
 921                 mode = FORK_FG;
 922                 if (flags & EV_BACKCMD) {
 923                         mode = FORK_NOJOB;
 924                         if (pipe(pip) < 0)
 925                                 error("Pipe call failed: %s", strerror(errno));
 926                 }
 927                 if (cmdentry.cmdtype == CMDNORMAL &&
 928                     cmd->ncmd.redirect == NULL &&
 929                     varlist.list == NULL &&
 930                     (mode == FORK_FG || mode == FORK_NOJOB) &&
 931                     !disvforkset() && !iflag && !mflag) {
 932                         vforkexecshell(jp, argv, environment(), path,
 933                             cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL);
 934                         goto parent;
 935                 }
 936                 if (forkshell(jp, cmd, mode) != 0)
 937                         goto parent;    /* at end of routine */
 938                 if (flags & EV_BACKCMD) {
 939                         FORCEINTON;
 940                         close(pip[0]);
 941                         if (pip[1] != 1) {
 942                                 dup2(pip[1], 1);
 943                                 close(pip[1]);
 944                         }
 945                         flags &= ~EV_BACKCMD;
 946                 }
 947                 flags |= EV_EXIT;
 948         }
 949
 950         /* This is the child process if a fork occurred. */
 951         /* Execute the command. */
 952         if (cmdentry.cmdtype == CMDFUNCTION) {
 953 #ifdef DEBUG
 954                 trputs("Shell function:  ");  trargs(argv);
 955 #endif
 956                 saveparam = shellparam;
 957                 shellparam.malloc = 0;
 958                 shellparam.reset = 1;
 959                 shellparam.nparam = argc - 1;
 960                 shellparam.p = argv + 1;
 961                 shellparam.optnext = NULL;
 962                 INTOFF;
 963                 savelocalvars = localvars;
 964                 localvars = NULL;
 965                 reffunc(cmdentry.u.func);
 966                 savehandler = handler;
 967                 if (setjmp(jmploc.loc)) {
 968                         freeparam(&shellparam);
 969                         shellparam = saveparam;
 970                         popredir();
 971                         unreffunc(cmdentry.u.func);
 972                         poplocalvars();
 973                         localvars = savelocalvars;
 974                         funcnest--;
 975                         handler = savehandler;
 976                         longjmp(handler->loc, 1);
 977                 }
 978                 handler = &jmploc;
 979                 funcnest++;
 980                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
 981                 INTON;
 982                 for (sp = varlist.list ; sp ; sp = sp->next)
 983                         mklocal(sp->text);
 984                 exitstatus = oexitstatus;
 985                 evaltree(getfuncnode(cmdentry.u.func),
 986                     flags & (EV_TESTED | EV_EXIT));
 987                 INTOFF;
 988                 unreffunc(cmdentry.u.func);
 989                 poplocalvars();
 990                 localvars = savelocalvars;
 991                 freeparam(&shellparam);
 992                 shellparam = saveparam;
 993                 handler = savehandler;
 994                 funcnest--;
 995                 popredir();
 996                 INTON;
 997                 if (evalskip == SKIPFUNC) {
 998                         evalskip = 0;
 999                         skipcount = 0;
1000                 }
1001                 if (jp)
1002                         exitshell(exitstatus);
1003         } else if (cmdentry.cmdtype == CMDBUILTIN) {
1004 #ifdef DEBUG
1005                 trputs("builtin command:  ");  trargs(argv);
1006 #endif
1007                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
1008                 if (flags == EV_BACKCMD) {
1009                         memout.nleft = 0;
1010                         memout.nextc = memout.buf;
1011                         memout.bufsize = 64;
1012                         mode |= REDIR_BACKQ;
1013                 }
1014                 savecmdname = commandname;
1015                 savetopfile = getcurrentfile();
1016                 cmdenviron = varlist.list;
1017                 e = -1;
1018                 savehandler = handler;
1019                 if (setjmp(jmploc.loc)) {
1020                         e = exception;
1021                         if (e == EXINT)
1022                                 exitstatus = SIGINT+128;
1023                         else if (e != EXEXIT)
1024                                 exitstatus = 2;
1025                         goto cmddone;
1026                 }
1027                 handler = &jmploc;
1028                 redirect(cmd->ncmd.redirect, mode);
1029                 /*
1030                  * If there is no command word, redirection errors should
1031                  * not be fatal but assignment errors should.
1032                  */
1033                 if (argc == 0)
1034                         cmdentry.special = 1;
1035                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1036                 if (argc > 0)
1037                         bltinsetlocale();
1038                 commandname = argv[0];
1039                 argptr = argv + 1;
1040                 nextopt_optptr = NULL;          /* initialize nextopt */
1041                 builtin_flags = flags;
1042                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1043                 flushall();
1044 cmddone:
1045                 if (argc > 0)
1046                         bltinunsetlocale();
1047                 cmdenviron = NULL;
1048                 out1 = &output;
1049                 out2 = &errout;
1050                 freestdout();
1051                 handler = savehandler;
1052                 commandname = savecmdname;
1053                 if (jp)
1054                         exitshell(exitstatus);
1055                 if (flags == EV_BACKCMD) {
1056                         backcmd->buf = memout.buf;
1057                         backcmd->nleft = memout.nextc - memout.buf;
1058                         memout.buf = NULL;
1059                 }
1060                 if (cmdentry.u.index != EXECCMD)
1061                         popredir();
1062                 if (e != -1) {
1063                         if ((e != EXERROR && e != EXEXEC)
1064                             || cmdentry.special)
1065                                 exraise(e);
1066                         popfilesupto(savetopfile);
1067                         if (flags != EV_BACKCMD)
1068                                 FORCEINTON;
1069                 }
1070         } else {
1071 #ifdef DEBUG
1072                 trputs("normal command:  ");  trargs(argv);
1073 #endif
1074                 redirect(cmd->ncmd.redirect, 0);
1075                 for (sp = varlist.list ; sp ; sp = sp->next)
1076                         setvareq(sp->text, VEXPORT|VSTACK);
1077                 envp = environment();
1078                 shellexec(argv, envp, path, cmdentry.u.index);
1079                 /*NOTREACHED*/
1080         }
1081         goto out;
1082
1083 parent: /* parent process gets here (if we forked) */
1084         if (mode == FORK_FG) {  /* argument to fork */
1085                 INTOFF;
1086                 exitstatus = waitforjob(jp, &realstatus);
1087                 INTON;
1088                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1089                         evalskip = SKIPBREAK;
1090                         skipcount = loopnest;
1091                 }
1092         } else if (mode == FORK_NOJOB) {
1093                 backcmd->fd = pip[0];
1094                 close(pip[1]);
1095                 backcmd->jp = jp;
1096         }
1097
1098 out:
1099         if (lastarg)
1100                 setvar("_", lastarg, 0);
1101         if (do_clearcmdentry)
1102                 clearcmdentry();
1103         popstackmark(&smark);
1104 }
1105
1106
1107
1108 /*
1109  * Search for a command.  This is called before we fork so that the
1110  * location of the command will be available in the parent as well as
1111  * the child.  The check for "goodname" is an overly conservative
1112  * check that the name will not be subject to expansion.
1113  */
1114
1115 static void
1116 prehash(union node *n)
1117 {
1118         struct cmdentry entry;
1119
1120         if (n && n->type == NCMD && n->ncmd.args)
1121                 if (goodname(n->ncmd.args->narg.text))
1122                         find_command(n->ncmd.args->narg.text, &entry, 0,
1123                                      pathval());
1124 }
1125
1126
1127
1128 /*
1129  * Builtin commands.  Builtin commands whose functions are closely
1130  * tied to evaluation are implemented here.
1131  */
1132
1133 /*
1134  * No command given, a bltin command with no arguments, or a bltin command
1135  * with an invalid name.
1136  */
1137
1138 int
1139 bltincmd(int argc, char **argv)
1140 {
1141         if (argc > 1) {
1142                 out2fmt_flush("%s: not found\n", argv[1]);
1143                 return 127;
1144         }
1145         /*
1146          * Preserve exitstatus of a previous possible redirection
1147          * as POSIX mandates
1148          */
1149         return exitstatus;
1150 }
1151
1152
1153 /*
1154  * Handle break and continue commands.  Break, continue, and return are
1155  * all handled by setting the evalskip flag.  The evaluation routines
1156  * above all check this flag, and if it is set they start skipping
1157  * commands rather than executing them.  The variable skipcount is
1158  * the number of loops to break/continue, or the number of function
1159  * levels to return.  (The latter is always 1.)  It should probably
1160  * be an error to break out of more loops than exist, but it isn't
1161  * in the standard shell so we don't make it one here.
1162  */
1163
1164 int
1165 breakcmd(int argc, char **argv)
1166 {
1167         int n = argc > 1 ? number(argv[1]) : 1;
1168
1169         if (n > loopnest)
1170                 n = loopnest;
1171         if (n > 0) {
1172                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1173                 skipcount = n;
1174         }
1175         return 0;
1176 }
1177
1178 /*
1179  * The `command' command.
1180  */
1181 int
1182 commandcmd(int argc, char **argv)
1183 {
1184         const char *path;
1185         int ch;
1186         int cmd = -1;
1187
1188         path = bltinlookup("PATH", 1);
1189
1190         optind = optreset = 1;
1191         opterr = 0;
1192         while ((ch = getopt(argc, argv, "pvV")) != -1) {
1193                 switch (ch) {
1194                 case 'p':
1195                         path = _PATH_STDPATH;
1196                         break;
1197                 case 'v':
1198                         cmd = TYPECMD_SMALLV;
1199                         break;
1200                 case 'V':
1201                         cmd = TYPECMD_BIGV;
1202                         break;
1203                 case '?':
1204                 default:
1205                         error("unknown option: -%c", optopt);
1206                 }
1207         }
1208         argc -= optind;
1209         argv += optind;
1210
1211         if (cmd != -1) {
1212                 if (argc != 1)
1213                         error("wrong number of arguments");
1214                 return typecmd_impl(2, argv - 1, cmd, path);
1215         }
1216         if (argc != 0)
1217                 error("commandcmd bad call");
1218
1219         /*
1220          * Do nothing successfully if no command was specified;
1221          * ksh also does this.
1222          */
1223         return(0);
1224 }
1225
1226
1227 /*
1228  * The return command.
1229  */
1230
1231 int
1232 returncmd(int argc, char **argv)
1233 {
1234         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1235
1236         if (funcnest) {
1237                 evalskip = SKIPFUNC;
1238                 skipcount = 1;
1239         } else {
1240                 /* skip the rest of the file */
1241                 evalskip = SKIPFILE;
1242                 skipcount = 1;
1243         }
1244         return ret;
1245 }
1246
1247
1248 int
1249 falsecmd(int argc __unused, char **argv __unused)
1250 {
1251         return 1;
1252 }
1253
1254
1255 int
1256 truecmd(int argc __unused, char **argv __unused)
1257 {
1258         return 0;
1259 }
1260
1261
1262 int
1263 execcmd(int argc, char **argv)
1264 {
1265         /*
1266          * Because we have historically not supported any options,
1267          * only treat "--" specially.
1268          */
1269         if (argc > 1 && strcmp(argv[1], "--") == 0)
1270                 argc--, argv++;
1271         if (argc > 1) {
1272                 struct strlist *sp;
1273
1274                 iflag = 0;              /* exit on error */
1275                 mflag = 0;
1276                 optschanged();
1277                 for (sp = cmdenviron; sp ; sp = sp->next)
1278                         setvareq(sp->text, VEXPORT|VSTACK);
1279                 shellexec(argv + 1, environment(), pathval(), 0);
1280
1281         }
1282         return 0;
1283 }
1284
1285
1286 int
1287 timescmd(int argc __unused, char **argv __unused)
1288 {
1289         struct rusage ru;
1290         long shumins, shsmins, chumins, chsmins;
1291         double shusecs, shssecs, chusecs, chssecs;
1292
1293         if (getrusage(RUSAGE_SELF, &ru) < 0)
1294                 return 1;
1295         shumins = ru.ru_utime.tv_sec / 60;
1296         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1297         shsmins = ru.ru_stime.tv_sec / 60;
1298         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1299         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1300                 return 1;
1301         chumins = ru.ru_utime.tv_sec / 60;
1302         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1303         chsmins = ru.ru_stime.tv_sec / 60;
1304         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1305         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1306             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1307         return 0;
1308 }