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 1.109 2011/06/12 23:06:04 jilles Exp $
  38  */
  39
  40 #include <sys/time.h>
  41 #include <sys/resource.h>
  42 #include <sys/wait.h> /* For WIFSIGNALED(status) */
  43
  44 #include <errno.h>
  45 #include <paths.h>
  46 #include <signal.h>
  47 #include <stdlib.h>
  48 #include <unistd.h>
  49
  50 /*
  51  * Evaluate a command.
  52  */
  53
  54 #include "shell.h"
  55 #include "nodes.h"
  56 #include "syntax.h"
  57 #include "expand.h"
  58 #include "parser.h"
  59 #include "jobs.h"
  60 #include "eval.h"
  61 #include "builtins.h"
  62 #include "options.h"
  63 #include "exec.h"
  64 #include "redir.h"
  65 #include "input.h"
  66 #include "output.h"
  67 #include "trap.h"
  68 #include "var.h"
  69 #include "memalloc.h"
  70 #include "error.h"
  71 #include "show.h"
  72 #include "mystring.h"
  73 #ifndef NO_HISTORY
  74 #include "myhistedit.h"
  75 #endif
  76
  77
  78 int evalskip;                   /* set if we are skipping commands */
  79 static int skipcount;           /* number of levels to skip */
  80 MKINIT int loopnest;            /* current loop nesting level */
  81 int funcnest;                   /* depth of function calls */
  82 static int builtin_flags;       /* evalcommand flags for builtins */
  83
  84
  85 const char *commandname;
  86 struct strlist *cmdenviron;
  87 int exitstatus;                 /* exit status of last command */
  88 int oexitstatus;                /* saved exit status */
  89
  90
  91 static void evalloop(union node *, int);
  92 static void evalfor(union node *, int);
  93 static void evalcase(union node *, int);
  94 static void evalsubshell(union node *, int);
  95 static void evalredir(union node *, int);
  96 static void expredir(union node *);
  97 static void evalpipe(union node *);
  98 static int is_valid_fast_cmdsubst(union node *n);
  99 static void evalcommand(union node *, int, struct backcmd *);
 100 static void prehash(union node *);
 101
 102
 103 /*
 104  * Called to reset things after an exception.
 105  */
 106
 107 #ifdef mkinit
 108 INCLUDE "eval.h"
 109
 110 RESET {
 111         evalskip = 0;
 112         loopnest = 0;
 113         funcnest = 0;
 114 }
 115 #endif
 116
 117
 118
 119 /*
 120  * The eval command.
 121  */
 122
 123 int
 124 evalcmd(int argc, char **argv)
 125 {
 126         char *p;
 127         char *concat;
 128         char **ap;
 129
 130         if (argc > 1) {
 131                 p = argv[1];
 132                 if (argc > 2) {
 133                         STARTSTACKSTR(concat);
 134                         ap = argv + 2;
 135                         for (;;) {
 136                                 STPUTS(p, concat);
 137                                 if ((p = *ap++) == NULL)
 138                                         break;
 139                                 STPUTC(' ', concat);
 140                         }
 141                         STPUTC('\0', concat);
 142                         p = grabstackstr(concat);
 143                 }
 144                 evalstring(p, builtin_flags & EV_TESTED);
 145         } else
 146                 exitstatus = 0;
 147         return exitstatus;
 148 }
 149
 150
 151 /*
 152  * Execute a command or commands contained in a string.
 153  */
 154
 155 void
 156 evalstring(char *s, int flags)
 157 {
 158         union node *n;
 159         struct stackmark smark;
 160         int flags_exit;
 161         int any;
 162
 163         flags_exit = flags & EV_EXIT;
 164         flags &= ~EV_EXIT;
 165         any = 0;
 166         setstackmark(&smark);
 167         setinputstring(s, 1);
 168         while ((n = parsecmd(0)) != NEOF) {
 169                 if (n != NULL && !nflag) {
 170                         if (flags_exit && preadateof())
 171                                 evaltree(n, flags | EV_EXIT);
 172                         else
 173                                 evaltree(n, flags);
 174                         any = 1;
 175                 }
 176                 popstackmark(&smark);
 177         }
 178         popfile();
 179         popstackmark(&smark);
 180         if (!any)
 181                 exitstatus = 0;
 182         if (flags_exit)
 183                 exraise(EXEXIT);
 184 }
 185
 186
 187 /*
 188  * Evaluate a parse tree.  The value is left in the global variable
 189  * exitstatus.
 190  */
 191
 192 void
 193 evaltree(union node *n, int flags)
 194 {
 195         int do_etest;
 196         union node *next;
 197
 198         do_etest = 0;
 199         if (n == NULL) {
 200                 TRACE(("evaltree(NULL) called\n"));
 201                 exitstatus = 0;
 202                 goto out;
 203         }
 204         do {
 205                 next = NULL;
 206 #ifndef NO_HISTORY
 207                 displayhist = 1;        /* show history substitutions done with fc */
 208 #endif
 209                 TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
 210                 switch (n->type) {
 211                 case NSEMI:
 212                         evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
 213                         if (evalskip)
 214                                 goto out;
 215                         next = n->nbinary.ch2;
 216                         break;
 217                 case NAND:
 218                         evaltree(n->nbinary.ch1, EV_TESTED);
 219                         if (evalskip || exitstatus != 0) {
 220                                 goto out;
 221                         }
 222                         next = n->nbinary.ch2;
 223                         break;
 224                 case NOR:
 225                         evaltree(n->nbinary.ch1, EV_TESTED);
 226                         if (evalskip || exitstatus == 0)
 227                                 goto out;
 228                         next = n->nbinary.ch2;
 229                         break;
 230                 case NREDIR:
 231                         evalredir(n, flags);
 232                         break;
 233                 case NSUBSHELL:
 234                         evalsubshell(n, flags);
 235                         do_etest = !(flags & EV_TESTED);
 236                         break;
 237                 case NBACKGND:
 238                         evalsubshell(n, flags);
 239                         break;
 240                 case NIF: {
 241                         evaltree(n->nif.test, EV_TESTED);
 242                         if (evalskip)
 243                                 goto out;
 244                         if (exitstatus == 0)
 245                                 next = n->nif.ifpart;
 246                         else if (n->nif.elsepart)
 247                                 next = n->nif.elsepart;
 248                         else
 249                                 exitstatus = 0;
 250                         break;
 251                 }
 252                 case NWHILE:
 253                 case NUNTIL:
 254                         evalloop(n, flags & ~EV_EXIT);
 255                         break;
 256                 case NFOR:
 257                         evalfor(n, flags & ~EV_EXIT);
 258                         break;
 259                 case NCASE:
 260                         evalcase(n, flags);
 261                         break;
 262                 case NDEFUN:
 263                         defun(n->narg.text, n->narg.next);
 264                         exitstatus = 0;
 265                         break;
 266                 case NNOT:
 267                         evaltree(n->nnot.com, EV_TESTED);
 268                         exitstatus = !exitstatus;
 269                         break;
 270
 271                 case NPIPE:
 272                         evalpipe(n);
 273                         do_etest = !(flags & EV_TESTED);
 274                         break;
 275                 case NCMD:
 276                         evalcommand(n, flags, NULL);
 277                         do_etest = !(flags & EV_TESTED);
 278                         break;
 279                 default:
 280                         out1fmt("Node type = %d\n", n->type);
 281                         flushout(&output);
 282                         break;
 283                 }
 284                 n = next;
 285         } while (n != NULL);
 286 out:
 287         if (pendingsigs)
 288                 dotrap();
 289         if (eflag && exitstatus != 0 && do_etest)
 290                 exitshell(exitstatus);
 291         if (flags & EV_EXIT)
 292                 exraise(EXEXIT);
 293 }
 294
 295
 296 static void
 297 evalloop(union node *n, int flags)
 298 {
 299         int status;
 300
 301         loopnest++;
 302         status = 0;
 303         for (;;) {
 304                 evaltree(n->nbinary.ch1, EV_TESTED);
 305                 if (evalskip) {
 306 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
 307                                 evalskip = 0;
 308                                 continue;
 309                         }
 310                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 311                                 evalskip = 0;
 312                         if (evalskip == SKIPFUNC || evalskip == SKIPFILE)
 313                                 status = exitstatus;
 314                         break;
 315                 }
 316                 if (n->type == NWHILE) {
 317                         if (exitstatus != 0)
 318                                 break;
 319                 } else {
 320                         if (exitstatus == 0)
 321                                 break;
 322                 }
 323                 evaltree(n->nbinary.ch2, flags);
 324                 status = exitstatus;
 325                 if (evalskip)
 326                         goto skipping;
 327         }
 328         loopnest--;
 329         exitstatus = status;
 330 }
 331
 332
 333
 334 static void
 335 evalfor(union node *n, int flags)
 336 {
 337         struct arglist arglist;
 338         union node *argp;
 339         struct strlist *sp;
 340         struct stackmark smark;
 341
 342         setstackmark(&smark);
 343         arglist.lastp = &arglist.list;
 344         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 345                 oexitstatus = exitstatus;
 346                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 347                 if (evalskip)
 348                         goto out;
 349         }
 350         *arglist.lastp = NULL;
 351
 352         exitstatus = 0;
 353         loopnest++;
 354         for (sp = arglist.list ; sp ; sp = sp->next) {
 355                 setvar(n->nfor.var, sp->text, 0);
 356                 evaltree(n->nfor.body, flags);
 357                 if (evalskip) {
 358                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 359                                 evalskip = 0;
 360                                 continue;
 361                         }
 362                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 363                                 evalskip = 0;
 364                         break;
 365                 }
 366         }
 367         loopnest--;
 368 out:
 369         popstackmark(&smark);
 370 }
 371
 372
 373
 374 static void
 375 evalcase(union node *n, int flags)
 376 {
 377         union node *cp;
 378         union node *patp;
 379         struct arglist arglist;
 380         struct stackmark smark;
 381
 382         setstackmark(&smark);
 383         arglist.lastp = &arglist.list;
 384         oexitstatus = exitstatus;
 385         exitstatus = 0;
 386         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 387         for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
 388                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 389                         if (casematch(patp, arglist.list->text)) {
 390                                 if (evalskip == 0) {
 391                                         evaltree(cp->nclist.body, flags);
 392                                 }
 393                                 goto out;
 394                         }
 395                 }
 396         }
 397 out:
 398         popstackmark(&smark);
 399 }
 400
 401
 402
 403 /*
 404  * Kick off a subshell to evaluate a tree.
 405  */
 406
 407 static void
 408 evalsubshell(union node *n, int flags)
 409 {
 410         struct job *jp;
 411         int backgnd = (n->type == NBACKGND);
 412
 413         oexitstatus = exitstatus;
 414         expredir(n->nredir.redirect);
 415         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
 416             forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
 417                 if (backgnd)
 418                         flags &=~ EV_TESTED;
 419                 redirect(n->nredir.redirect, 0);
 420                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 421         } else if (!backgnd) {
 422                 INTOFF;
 423                 exitstatus = waitforjob(jp, NULL);
 424                 INTON;
 425         } else
 426                 exitstatus = 0;
 427 }
 428
 429
 430 /*
 431  * Evaluate a redirected compound command.
 432  */
 433
 434 static void
 435 evalredir(union node *n, int flags)
 436 {
 437         struct jmploc jmploc;
 438         struct jmploc *savehandler;
 439         volatile int in_redirect = 1;
 440
 441         oexitstatus = exitstatus;
 442         expredir(n->nredir.redirect);
 443         savehandler = handler;
 444         if (setjmp(jmploc.loc)) {
 445                 int e;
 446
 447                 handler = savehandler;
 448                 e = exception;
 449                 popredir();
 450                 if (e == EXERROR || e == EXEXEC) {
 451                         if (in_redirect) {
 452                                 exitstatus = 2;
 453                                 return;
 454                         }
 455                 }
 456                 longjmp(handler->loc, 1);
 457         } else {
 458                 INTOFF;
 459                 handler = &jmploc;
 460                 redirect(n->nredir.redirect, REDIR_PUSH);
 461                 in_redirect = 0;
 462                 INTON;
 463                 evaltree(n->nredir.n, flags);
 464         }
 465         INTOFF;
 466         handler = savehandler;
 467         popredir();
 468         INTON;
 469 }
 470
 471
 472 /*
 473  * Compute the names of the files in a redirection list.
 474  */
 475
 476 static void
 477 expredir(union node *n)
 478 {
 479         union node *redir;
 480
 481         for (redir = n ; redir ; redir = redir->nfile.next) {
 482                 struct arglist fn;
 483                 fn.lastp = &fn.list;
 484                 switch (redir->type) {
 485                 case NFROM:
 486                 case NTO:
 487                 case NFROMTO:
 488                 case NAPPEND:
 489                 case NCLOBBER:
 490                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 491                         redir->nfile.expfname = fn.list->text;
 492                         break;
 493                 case NFROMFD:
 494                 case NTOFD:
 495                         if (redir->ndup.vname) {
 496                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
 497                                 fixredir(redir, fn.list->text, 1);
 498                         }
 499                         break;
 500                 }
 501         }
 502 }
 503
 504
 505
 506 /*
 507  * Evaluate a pipeline.  All the processes in the pipeline are children
 508  * of the process creating the pipeline.  (This differs from some versions
 509  * of the shell, which make the last process in a pipeline the parent
 510  * of all the rest.)
 511  */
 512
 513 static void
 514 evalpipe(union node *n)
 515 {
 516         struct job *jp;
 517         struct nodelist *lp;
 518         int pipelen;
 519         int prevfd;
 520         int pip[2];
 521
 522         TRACE(("evalpipe(%p) called\n", (void *)n));
 523         pipelen = 0;
 524         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
 525                 pipelen++;
 526         INTOFF;
 527         jp = makejob(n, pipelen);
 528         prevfd = -1;
 529         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
 530                 prehash(lp->n);
 531                 pip[1] = -1;
 532                 if (lp->next) {
 533                         if (pipe(pip) < 0) {
 534                                 if (prevfd >= 0)
 535                                         close(prevfd);
 536                                 error("Pipe call failed: %s", strerror(errno));
 537                         }
 538                 }
 539                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
 540                         INTON;
 541                         if (prevfd > 0) {
 542                                 dup2(prevfd, 0);
 543                                 close(prevfd);
 544                         }
 545                         if (pip[1] >= 0) {
 546                                 if (!(prevfd >= 0 && pip[0] == 0))
 547                                         close(pip[0]);
 548                                 if (pip[1] != 1) {
 549                                         dup2(pip[1], 1);
 550                                         close(pip[1]);
 551                                 }
 552                         }
 553                         evaltree(lp->n, EV_EXIT);
 554                 }
 555                 if (prevfd >= 0)
 556                         close(prevfd);
 557                 prevfd = pip[0];
 558                 if (pip[1] != -1)
 559                         close(pip[1]);
 560         }
 561         INTON;
 562         if (n->npipe.backgnd == 0) {
 563                 INTOFF;
 564                 exitstatus = waitforjob(jp, NULL);
 565                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 566                 INTON;
 567         } else
 568                 exitstatus = 0;
 569 }
 570
 571
 572
 573 static int
 574 is_valid_fast_cmdsubst(union node *n)
 575 {
 576
 577         return (n->type == NCMD);
 578 }
 579
 580 /*
 581  * Execute a command inside back quotes.  If it's a builtin command, we
 582  * want to save its output in a block obtained from malloc.  Otherwise
 583  * we fork off a subprocess and get the output of the command via a pipe.
 584  * Should be called with interrupts off.
 585  */
 586
 587 void
 588 evalbackcmd(union node *n, struct backcmd *result)
 589 {
 590         int pip[2];
 591         struct job *jp;
 592         struct stackmark smark;         /* unnecessary */
 593         struct jmploc jmploc;
 594         struct jmploc *savehandler;
 595         struct localvar *savelocalvars;
 596
 597         setstackmark(&smark);
 598         result->fd = -1;
 599         result->buf = NULL;
 600         result->nleft = 0;
 601         result->jp = NULL;
 602         if (n == NULL) {
 603                 exitstatus = 0;
 604                 goto out;
 605         }
 606         if (is_valid_fast_cmdsubst(n)) {
 607                 exitstatus = oexitstatus;
 608                 savelocalvars = localvars;
 609                 localvars = NULL;
 610                 forcelocal++;
 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                                 forcelocal--;
 618                                 poplocalvars();
 619                                 localvars = savelocalvars;
 620                                 longjmp(handler->loc, 1);
 621                         }
 622                 } else {
 623                         handler = &jmploc;
 624                         evalcommand(n, EV_BACKCMD, result);
 625                 }
 626                 handler = savehandler;
 627                 forcelocal--;
 628                 poplocalvars();
 629                 localvars = savelocalvars;
 630         } else {
 631                 exitstatus = 0;
 632                 if (pipe(pip) < 0)
 633                         error("Pipe call failed: %s", strerror(errno));
 634                 jp = makejob(n, 1);
 635                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 636                         FORCEINTON;
 637                         close(pip[0]);
 638                         if (pip[1] != 1) {
 639                                 dup2(pip[1], 1);
 640                                 close(pip[1]);
 641                         }
 642                         evaltree(n, EV_EXIT);
 643                 }
 644                 close(pip[1]);
 645                 result->fd = pip[0];
 646                 result->jp = jp;
 647         }
 648 out:
 649         popstackmark(&smark);
 650         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 651                 result->fd, result->buf, result->nleft, result->jp));
 652 }
 653
 654 /*
 655  * Check if a builtin can safely be executed in the same process,
 656  * even though it should be in a subshell (command substitution).
 657  * Note that jobid, jobs, times and trap can show information not
 658  * available in a child process; this is deliberate.
 659  * The arguments should already have been expanded.
 660  */
 661 static int
 662 safe_builtin(int idx, int argc, char **argv)
 663 {
 664         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
 665             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
 666             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
 667             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
 668             idx == TYPECMD)
 669                 return (1);
 670         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 671             idx == UMASKCMD)
 672                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 673         if (idx == SETCMD)
 674                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 675                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 676                     argv[1][2] == '\0'));
 677         return (0);
 678 }
 679
 680 /*
 681  * Execute a simple command.
 682  * Note: This may or may not return if (flags & EV_EXIT).
 683  */
 684
 685 static void
 686 evalcommand(union node *cmd, int flgs, struct backcmd *backcmd)
 687 {
 688         struct stackmark smark;
 689         union node *argp;
 690         struct arglist arglist;
 691         struct arglist varlist;
 692         volatile int flags = flgs;
 693         char **volatile argv;
 694         volatile int argc;
 695         char **envp;
 696         int varflag;
 697         struct strlist *sp;
 698         int mode;
 699         int pip[2];
 700         struct cmdentry cmdentry;
 701         struct job *volatile jp;
 702         struct jmploc jmploc;
 703         struct jmploc *savehandler;
 704         const char *savecmdname;
 705         struct shparam saveparam;
 706         struct localvar *savelocalvars;
 707         struct parsefile *savetopfile;
 708         volatile int e;
 709         char *volatile lastarg;
 710         int realstatus;
 711         volatile int do_clearcmdentry;
 712         const char *path = pathval();
 713
 714         /* First expand the arguments. */
 715         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 716         setstackmark(&smark);
 717         arglist.lastp = &arglist.list;
 718         varlist.lastp = &varlist.list;
 719         varflag = 1;
 720         jp = NULL;
 721         do_clearcmdentry = 0;
 722         oexitstatus = exitstatus;
 723         exitstatus = 0;
 724         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 725                 if (varflag && isassignment(argp->narg.text)) {
 726                         expandarg(argp, &varlist, EXP_VARTILDE);
 727                         continue;
 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, *ps4;
 756                 ps4 = expandstr(ps4val());
 757                 out2str(ps4 != NULL ? ps4 : ps4val());
 758                 for (sp = varlist.list ; sp ; sp = sp->next) {
 759                         if (sep != 0)
 760                                 out2c(' ');
 761                         p = strchr(sp->text, '=');
 762                         if (p != NULL) {
 763                                 p++;
 764                                 outbin(sp->text, p - sp->text, out2);
 765                                 out2qstr(p);
 766                         } else
 767                                 out2qstr(sp->text);
 768                         sep = ' ';
 769                 }
 770                 for (sp = arglist.list ; sp ; sp = sp->next) {
 771                         if (sep != 0)
 772                                 out2c(' ');
 773                         /* Disambiguate command looking like assignment. */
 774                         if (sp == arglist.list &&
 775                                         strchr(sp->text, '=') != NULL &&
 776                                         strchr(sp->text, '\'') == NULL) {
 777                                 out2c('\'');
 778                                 out2str(sp->text);
 779                                 out2c('\'');
 780                         } else
 781                                 out2qstr(sp->text);
 782                         sep = ' ';
 783                 }
 784                 out2c('\n');
 785                 flushout(&errout);
 786         }
 787
 788         /* Now locate the command. */
 789         if (argc == 0) {
 790                 /* Variable assignment(s) without command */
 791                 cmdentry.cmdtype = CMDBUILTIN;
 792                 cmdentry.u.index = BLTINCMD;
 793                 cmdentry.special = 0;
 794         } else {
 795                 static const char PATH[] = "PATH=";
 796                 int cmd_flags = 0, bltinonly = 0;
 797
 798                 /*
 799                  * Modify the command lookup path, if a PATH= assignment
 800                  * is present
 801                  */
 802                 for (sp = varlist.list ; sp ; sp = sp->next)
 803                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 804                                 path = sp->text + sizeof(PATH) - 1;
 805                                 /*
 806                                  * On `PATH=... command`, we need to make
 807                                  * sure that the command isn't using the
 808                                  * non-updated hash table of the outer PATH
 809                                  * setting and we need to make sure that
 810                                  * the hash table isn't filled with items
 811                                  * from the temporary setting.
 812                                  *
 813                                  * It would be better to forbit using and
 814                                  * updating the table while this command
 815                                  * runs, by the command finding mechanism
 816                                  * is heavily integrated with hash handling,
 817                                  * so we just delete the hash before and after
 818                                  * the command runs. Partly deleting like
 819                                  * changepatch() does doesn't seem worth the
 820                                  * bookinging effort, since most such runs add
 821                                  * directories in front of the new PATH.
 822                                  */
 823                                 clearcmdentry();
 824                                 do_clearcmdentry = 1;
 825                         }
 826
 827                 for (;;) {
 828                         if (bltinonly) {
 829                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 830                                 if (cmdentry.u.index < 0) {
 831                                         cmdentry.u.index = BLTINCMD;
 832                                         argv--;
 833                                         argc++;
 834                                         break;
 835                                 }
 836                         } else
 837                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 838                         /* implement the bltin and command builtins here */
 839                         if (cmdentry.cmdtype != CMDBUILTIN)
 840                                 break;
 841                         if (cmdentry.u.index == BLTINCMD) {
 842                                 if (argc == 1)
 843                                         break;
 844                                 argv++;
 845                                 argc--;
 846                                 bltinonly = 1;
 847                         } else if (cmdentry.u.index == COMMANDCMD) {
 848                                 if (argc == 1)
 849                                         break;
 850                                 if (!strcmp(argv[1], "-p")) {
 851                                         if (argc == 2)
 852                                                 break;
 853                                         if (argv[2][0] == '-') {
 854                                                 if (strcmp(argv[2], "--"))
 855                                                         break;
 856                                                 if (argc == 3)
 857                                                         break;
 858                                                 argv += 3;
 859                                                 argc -= 3;
 860                                         } else {
 861                                                 argv += 2;
 862                                                 argc -= 2;
 863                                         }
 864                                         path = _PATH_STDPATH;
 865                                         clearcmdentry();
 866                                         do_clearcmdentry = 1;
 867                                 } else if (!strcmp(argv[1], "--")) {
 868                                         if (argc == 2)
 869                                                 break;
 870                                         argv += 2;
 871                                         argc -= 2;
 872                                 } else if (argv[1][0] == '-')
 873                                         break;
 874                                 else {
 875                                         argv++;
 876                                         argc--;
 877                                 }
 878                                 cmd_flags |= DO_NOFUNC;
 879                                 bltinonly = 0;
 880                         } else
 881                                 break;
 882                 }
 883                 /*
 884                  * Special builtins lose their special properties when
 885                  * called via 'command'.
 886                  */
 887                 if (cmd_flags & DO_NOFUNC)
 888                         cmdentry.special = 0;
 889         }
 890
 891         /* Fork off a child process if necessary. */
 892         if (cmd->ncmd.backgnd
 893          || ((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 894             && ((flags & EV_EXIT) == 0 || have_traps()))
 895          || ((flags & EV_BACKCMD) != 0
 896             && (cmdentry.cmdtype != CMDBUILTIN ||
 897                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 898                 jp = makejob(cmd, 1);
 899                 mode = cmd->ncmd.backgnd;
 900                 if (flags & EV_BACKCMD) {
 901                         mode = FORK_NOJOB;
 902                         if (pipe(pip) < 0)
 903                                 error("Pipe call failed: %s", strerror(errno));
 904                 }
 905                 if (forkshell(jp, cmd, mode) != 0)
 906                         goto parent;    /* at end of routine */
 907                 if (flags & EV_BACKCMD) {
 908                         FORCEINTON;
 909                         close(pip[0]);
 910                         if (pip[1] != 1) {
 911                                 dup2(pip[1], 1);
 912                                 close(pip[1]);
 913                         }
 914                 }
 915                 flags |= EV_EXIT;
 916         }
 917
 918         /* This is the child process if a fork occurred. */
 919         /* Execute the command. */
 920         if (cmdentry.cmdtype == CMDFUNCTION) {
 921 #ifdef DEBUG
 922                 trputs("Shell function:  ");  trargs(argv);
 923 #endif
 924                 saveparam = shellparam;
 925                 shellparam.malloc = 0;
 926                 shellparam.reset = 1;
 927                 shellparam.nparam = argc - 1;
 928                 shellparam.p = argv + 1;
 929                 shellparam.optnext = NULL;
 930                 INTOFF;
 931                 savelocalvars = localvars;
 932                 localvars = NULL;
 933                 reffunc(cmdentry.u.func);
 934                 savehandler = handler;
 935                 if (setjmp(jmploc.loc)) {
 936                         freeparam(&shellparam);
 937                         shellparam = saveparam;
 938                         popredir();
 939                         unreffunc(cmdentry.u.func);
 940                         poplocalvars();
 941                         localvars = savelocalvars;
 942                         funcnest--;
 943                         handler = savehandler;
 944                         longjmp(handler->loc, 1);
 945                 }
 946                 handler = &jmploc;
 947                 funcnest++;
 948                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
 949                 INTON;
 950                 for (sp = varlist.list ; sp ; sp = sp->next)
 951                         mklocal(sp->text);
 952                 exitstatus = oexitstatus;
 953                 evaltree(getfuncnode(cmdentry.u.func),
 954                     flags & (EV_TESTED | EV_EXIT));
 955                 INTOFF;
 956                 unreffunc(cmdentry.u.func);
 957                 poplocalvars();
 958                 localvars = savelocalvars;
 959                 freeparam(&shellparam);
 960                 shellparam = saveparam;
 961                 handler = savehandler;
 962                 funcnest--;
 963                 popredir();
 964                 INTON;
 965                 if (evalskip == SKIPFUNC) {
 966                         evalskip = 0;
 967                         skipcount = 0;
 968                 }
 969                 if (jp)
 970                         exitshell(exitstatus);
 971         } else if (cmdentry.cmdtype == CMDBUILTIN) {
 972 #ifdef DEBUG
 973                 trputs("builtin command:  ");  trargs(argv);
 974 #endif
 975                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
 976                 if (flags == EV_BACKCMD) {
 977                         memout.nleft = 0;
 978                         memout.nextc = memout.buf;
 979                         memout.bufsize = 64;
 980                         mode |= REDIR_BACKQ;
 981                         cmdentry.special = 0;
 982                 }
 983                 savecmdname = commandname;
 984                 savetopfile = getcurrentfile();
 985                 cmdenviron = varlist.list;
 986                 e = -1;
 987                 savehandler = handler;
 988                 if (setjmp(jmploc.loc)) {
 989                         e = exception;
 990                         if (e == EXINT)
 991                                 exitstatus = SIGINT+128;
 992                         else if (e != EXEXIT)
 993                                 exitstatus = 2;
 994                         goto cmddone;
 995                 }
 996                 handler = &jmploc;
 997                 redirect(cmd->ncmd.redirect, mode);
 998                 /*
 999                  * If there is no command word, redirection errors should
1000                  * not be fatal but assignment errors should.
1001                  */
1002                 if (argc == 0 && !(flags & EV_BACKCMD))
1003                         cmdentry.special = 1;
1004                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1005                 if (argc > 0)
1006                         bltinsetlocale();
1007                 commandname = argv[0];
1008                 argptr = argv + 1;
1009                 nextopt_optptr = NULL;          /* initialize nextopt */
1010                 builtin_flags = flags;
1011                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1012                 flushall();
1013 cmddone:
1014                 if (argc > 0)
1015                         bltinunsetlocale();
1016                 cmdenviron = NULL;
1017                 out1 = &output;
1018                 out2 = &errout;
1019                 freestdout();
1020                 handler = savehandler;
1021                 commandname = savecmdname;
1022                 if (jp)
1023                         exitshell(exitstatus);
1024                 if (flags == EV_BACKCMD) {
1025                         backcmd->buf = memout.buf;
1026                         backcmd->nleft = memout.nextc - memout.buf;
1027                         memout.buf = NULL;
1028                 }
1029                 if (cmdentry.u.index != EXECCMD)
1030                         popredir();
1031                 if (e != -1) {
1032                         if ((e != EXERROR && e != EXEXEC)
1033                             || cmdentry.special)
1034                                 exraise(e);
1035                         popfilesupto(savetopfile);
1036                         if (flags != EV_BACKCMD)
1037                                 FORCEINTON;
1038                 }
1039         } else {
1040 #ifdef DEBUG
1041                 trputs("normal command:  ");  trargs(argv);
1042 #endif
1043                 redirect(cmd->ncmd.redirect, 0);
1044                 for (sp = varlist.list ; sp ; sp = sp->next)
1045                         setvareq(sp->text, VEXPORT|VSTACK);
1046                 envp = environment();
1047                 shellexec(argv, envp, path, cmdentry.u.index);
1048                 /*NOTREACHED*/
1049         }
1050         goto out;
1051
1052 parent: /* parent process gets here (if we forked) */
1053         if (mode == FORK_FG) {  /* argument to fork */
1054                 INTOFF;
1055                 exitstatus = waitforjob(jp, &realstatus);
1056                 INTON;
1057                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1058                         evalskip = SKIPBREAK;
1059                         skipcount = loopnest;
1060                 }
1061         } else if (mode == FORK_NOJOB) {
1062                 backcmd->fd = pip[0];
1063                 close(pip[1]);
1064                 backcmd->jp = jp;
1065         } else
1066                 exitstatus = 0;
1067
1068 out:
1069         if (lastarg)
1070                 setvar("_", lastarg, 0);
1071         if (do_clearcmdentry)
1072                 clearcmdentry();
1073         popstackmark(&smark);
1074 }
1075
1076
1077
1078 /*
1079  * Search for a command.  This is called before we fork so that the
1080  * location of the command will be available in the parent as well as
1081  * the child.  The check for "goodname" is an overly conservative
1082  * check that the name will not be subject to expansion.
1083  */
1084
1085 static void
1086 prehash(union node *n)
1087 {
1088         struct cmdentry entry;
1089
1090         if (n && n->type == NCMD && n->ncmd.args)
1091                 if (goodname(n->ncmd.args->narg.text))
1092                         find_command(n->ncmd.args->narg.text, &entry, 0,
1093                                      pathval());
1094 }
1095
1096
1097
1098 /*
1099  * Builtin commands.  Builtin commands whose functions are closely
1100  * tied to evaluation are implemented here.
1101  */
1102
1103 /*
1104  * No command given, a bltin command with no arguments, or a bltin command
1105  * with an invalid name.
1106  */
1107
1108 int
1109 bltincmd(int argc, char **argv)
1110 {
1111         if (argc > 1) {
1112                 out2fmt_flush("%s: not found\n", argv[1]);
1113                 return 127;
1114         }
1115         /*
1116          * Preserve exitstatus of a previous possible redirection
1117          * as POSIX mandates
1118          */
1119         return exitstatus;
1120 }
1121
1122
1123 /*
1124  * Handle break and continue commands.  Break, continue, and return are
1125  * all handled by setting the evalskip flag.  The evaluation routines
1126  * above all check this flag, and if it is set they start skipping
1127  * commands rather than executing them.  The variable skipcount is
1128  * the number of loops to break/continue, or the number of function
1129  * levels to return.  (The latter is always 1.)  It should probably
1130  * be an error to break out of more loops than exist, but it isn't
1131  * in the standard shell so we don't make it one here.
1132  */
1133
1134 int
1135 breakcmd(int argc, char **argv)
1136 {
1137         int n = argc > 1 ? number(argv[1]) : 1;
1138
1139         if (n > loopnest)
1140                 n = loopnest;
1141         if (n > 0) {
1142                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1143                 skipcount = n;
1144         }
1145         return 0;
1146 }
1147
1148 /*
1149  * The `command' command.
1150  */
1151 int
1152 commandcmd(int argc, char **argv)
1153 {
1154         const char *path;
1155         int ch;
1156         int cmd = -1;
1157
1158         path = bltinlookup("PATH", 1);
1159
1160         optind = optreset = 1;
1161         opterr = 0;
1162         while ((ch = getopt(argc, argv, "pvV")) != -1) {
1163                 switch (ch) {
1164                 case 'p':
1165                         path = _PATH_STDPATH;
1166                         break;
1167                 case 'v':
1168                         cmd = TYPECMD_SMALLV;
1169                         break;
1170                 case 'V':
1171                         cmd = TYPECMD_BIGV;
1172                         break;
1173                 case '?':
1174                 default:
1175                         error("unknown option: -%c", optopt);
1176                 }
1177         }
1178         argc -= optind;
1179         argv += optind;
1180
1181         if (cmd != -1) {
1182                 if (argc != 1)
1183                         error("wrong number of arguments");
1184                 return typecmd_impl(2, argv - 1, cmd, path);
1185         }
1186         if (argc != 0)
1187                 error("commandcmd bad call");
1188
1189         /*
1190          * Do nothing successfully if no command was specified;
1191          * ksh also does this.
1192          */
1193         return(0);
1194 }
1195
1196
1197 /*
1198  * The return command.
1199  */
1200
1201 int
1202 returncmd(int argc, char **argv)
1203 {
1204         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1205
1206         if (funcnest) {
1207                 evalskip = SKIPFUNC;
1208                 skipcount = 1;
1209         } else {
1210                 /* skip the rest of the file */
1211                 evalskip = SKIPFILE;
1212                 skipcount = 1;
1213         }
1214         return ret;
1215 }
1216
1217
1218 int
1219 falsecmd(int argc __unused, char **argv __unused)
1220 {
1221         return 1;
1222 }
1223
1224
1225 int
1226 truecmd(int argc __unused, char **argv __unused)
1227 {
1228         return 0;
1229 }
1230
1231
1232 int
1233 execcmd(int argc, char **argv)
1234 {
1235         /*
1236          * Because we have historically not supported any options,
1237          * only treat "--" specially.
1238          */
1239         if (argc > 1 && strcmp(argv[1], "--") == 0)
1240                 argc--, argv++;
1241         if (argc > 1) {
1242                 struct strlist *sp;
1243
1244                 iflag = 0;              /* exit on error */
1245                 mflag = 0;
1246                 optschanged();
1247                 for (sp = cmdenviron; sp ; sp = sp->next)
1248                         setvareq(sp->text, VEXPORT|VSTACK);
1249                 shellexec(argv + 1, environment(), pathval(), 0);
1250
1251         }
1252         return 0;
1253 }
1254
1255
1256 int
1257 timescmd(int argc __unused, char **argv __unused)
1258 {
1259         struct rusage ru;
1260         long shumins, shsmins, chumins, chsmins;
1261         double shusecs, shssecs, chusecs, chssecs;
1262
1263         if (getrusage(RUSAGE_SELF, &ru) < 0)
1264                 return 1;
1265         shumins = ru.ru_utime.tv_sec / 60;
1266         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1267         shsmins = ru.ru_stime.tv_sec / 60;
1268         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1269         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1270                 return 1;
1271         chumins = ru.ru_utime.tv_sec / 60;
1272         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1273         chsmins = ru.ru_stime.tv_sec / 60;
1274         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1275         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1276             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1277         return 0;
1278 }