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 1.111 2011/06/17 13:03:49 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);
 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                                 while (cp->nclist.next &&
 391                                     cp->type == NCLISTFALLTHRU) {
 392                                         if (evalskip != 0)
 393                                                 break;
 394                                         evaltree(cp->nclist.body,
 395                                             flags & ~EV_EXIT);
 396                                         cp = cp->nclist.next;
 397                                 }
 398                                 if (evalskip == 0) {
 399                                         evaltree(cp->nclist.body, flags);
 400                                 }
 401                                 goto out;
 402                         }
 403                 }
 404         }
 405 out:
 406         popstackmark(&smark);
 407 }
 408
 409
 410
 411 /*
 412  * Kick off a subshell to evaluate a tree.
 413  */
 414
 415 static void
 416 evalsubshell(union node *n, int flags)
 417 {
 418         struct job *jp;
 419         int backgnd = (n->type == NBACKGND);
 420
 421         oexitstatus = exitstatus;
 422         expredir(n->nredir.redirect);
 423         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
 424             forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
 425                 if (backgnd)
 426                         flags &=~ EV_TESTED;
 427                 redirect(n->nredir.redirect, 0);
 428                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 429         } else if (!backgnd) {
 430                 INTOFF;
 431                 exitstatus = waitforjob(jp, NULL);
 432                 INTON;
 433         } else
 434                 exitstatus = 0;
 435 }
 436
 437
 438 /*
 439  * Evaluate a redirected compound command.
 440  */
 441
 442 static void
 443 evalredir(union node *n, int flags)
 444 {
 445         struct jmploc jmploc;
 446         struct jmploc *savehandler;
 447         volatile int in_redirect = 1;
 448
 449         oexitstatus = exitstatus;
 450         expredir(n->nredir.redirect);
 451         savehandler = handler;
 452         if (setjmp(jmploc.loc)) {
 453                 int e;
 454
 455                 handler = savehandler;
 456                 e = exception;
 457                 popredir();
 458                 if (e == EXERROR || e == EXEXEC) {
 459                         if (in_redirect) {
 460                                 exitstatus = 2;
 461                                 return;
 462                         }
 463                 }
 464                 longjmp(handler->loc, 1);
 465         } else {
 466                 INTOFF;
 467                 handler = &jmploc;
 468                 redirect(n->nredir.redirect, REDIR_PUSH);
 469                 in_redirect = 0;
 470                 INTON;
 471                 evaltree(n->nredir.n, flags);
 472         }
 473         INTOFF;
 474         handler = savehandler;
 475         popredir();
 476         INTON;
 477 }
 478
 479
 480 /*
 481  * Compute the names of the files in a redirection list.
 482  */
 483
 484 static void
 485 expredir(union node *n)
 486 {
 487         union node *redir;
 488
 489         for (redir = n ; redir ; redir = redir->nfile.next) {
 490                 struct arglist fn;
 491                 fn.lastp = &fn.list;
 492                 switch (redir->type) {
 493                 case NFROM:
 494                 case NTO:
 495                 case NFROMTO:
 496                 case NAPPEND:
 497                 case NCLOBBER:
 498                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 499                         redir->nfile.expfname = fn.list->text;
 500                         break;
 501                 case NFROMFD:
 502                 case NTOFD:
 503                         if (redir->ndup.vname) {
 504                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
 505                                 fixredir(redir, fn.list->text, 1);
 506                         }
 507                         break;
 508                 }
 509         }
 510 }
 511
 512
 513
 514 /*
 515  * Evaluate a pipeline.  All the processes in the pipeline are children
 516  * of the process creating the pipeline.  (This differs from some versions
 517  * of the shell, which make the last process in a pipeline the parent
 518  * of all the rest.)
 519  */
 520
 521 static void
 522 evalpipe(union node *n)
 523 {
 524         struct job *jp;
 525         struct nodelist *lp;
 526         int pipelen;
 527         int prevfd;
 528         int pip[2];
 529
 530         TRACE(("evalpipe(%p) called\n", (void *)n));
 531         pipelen = 0;
 532         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
 533                 pipelen++;
 534         INTOFF;
 535         jp = makejob(n, pipelen);
 536         prevfd = -1;
 537         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
 538                 prehash(lp->n);
 539                 pip[1] = -1;
 540                 if (lp->next) {
 541                         if (pipe(pip) < 0) {
 542                                 if (prevfd >= 0)
 543                                         close(prevfd);
 544                                 error("Pipe call failed: %s", strerror(errno));
 545                         }
 546                 }
 547                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
 548                         INTON;
 549                         if (prevfd > 0) {
 550                                 dup2(prevfd, 0);
 551                                 close(prevfd);
 552                         }
 553                         if (pip[1] >= 0) {
 554                                 if (!(prevfd >= 0 && pip[0] == 0))
 555                                         close(pip[0]);
 556                                 if (pip[1] != 1) {
 557                                         dup2(pip[1], 1);
 558                                         close(pip[1]);
 559                                 }
 560                         }
 561                         evaltree(lp->n, EV_EXIT);
 562                 }
 563                 if (prevfd >= 0)
 564                         close(prevfd);
 565                 prevfd = pip[0];
 566                 if (pip[1] != -1)
 567                         close(pip[1]);
 568         }
 569         INTON;
 570         if (n->npipe.backgnd == 0) {
 571                 INTOFF;
 572                 exitstatus = waitforjob(jp, NULL);
 573                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 574                 INTON;
 575         } else
 576                 exitstatus = 0;
 577 }
 578
 579
 580
 581 static int
 582 is_valid_fast_cmdsubst(union node *n)
 583 {
 584
 585         return (n->type == NCMD);
 586 }
 587
 588 /*
 589  * Execute a command inside back quotes.  If it's a builtin command, we
 590  * want to save its output in a block obtained from malloc.  Otherwise
 591  * we fork off a subprocess and get the output of the command via a pipe.
 592  * Should be called with interrupts off.
 593  */
 594
 595 void
 596 evalbackcmd(union node *n, struct backcmd *result)
 597 {
 598         int pip[2];
 599         struct job *jp;
 600         struct stackmark smark;         /* unnecessary */
 601         struct jmploc jmploc;
 602         struct jmploc *savehandler;
 603         struct localvar *savelocalvars;
 604
 605         setstackmark(&smark);
 606         result->fd = -1;
 607         result->buf = NULL;
 608         result->nleft = 0;
 609         result->jp = NULL;
 610         if (n == NULL) {
 611                 exitstatus = 0;
 612                 goto out;
 613         }
 614         if (is_valid_fast_cmdsubst(n)) {
 615                 exitstatus = oexitstatus;
 616                 savelocalvars = localvars;
 617                 localvars = NULL;
 618                 forcelocal++;
 619                 savehandler = handler;
 620                 if (setjmp(jmploc.loc)) {
 621                         if (exception == EXERROR || exception == EXEXEC)
 622                                 exitstatus = 2;
 623                         else if (exception != 0) {
 624                                 handler = savehandler;
 625                                 forcelocal--;
 626                                 poplocalvars();
 627                                 localvars = savelocalvars;
 628                                 longjmp(handler->loc, 1);
 629                         }
 630                 } else {
 631                         handler = &jmploc;
 632                         evalcommand(n, EV_BACKCMD, result);
 633                 }
 634                 handler = savehandler;
 635                 forcelocal--;
 636                 poplocalvars();
 637                 localvars = savelocalvars;
 638         } else {
 639                 exitstatus = 0;
 640                 if (pipe(pip) < 0)
 641                         error("Pipe call failed: %s", strerror(errno));
 642                 jp = makejob(n, 1);
 643                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 644                         FORCEINTON;
 645                         close(pip[0]);
 646                         if (pip[1] != 1) {
 647                                 dup2(pip[1], 1);
 648                                 close(pip[1]);
 649                         }
 650                         evaltree(n, EV_EXIT);
 651                 }
 652                 close(pip[1]);
 653                 result->fd = pip[0];
 654                 result->jp = jp;
 655         }
 656 out:
 657         popstackmark(&smark);
 658         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 659                 result->fd, result->buf, result->nleft, result->jp));
 660 }
 661
 662 /*
 663  * Check if a builtin can safely be executed in the same process,
 664  * even though it should be in a subshell (command substitution).
 665  * Note that jobid, jobs, times and trap can show information not
 666  * available in a child process; this is deliberate.
 667  * The arguments should already have been expanded.
 668  */
 669 static int
 670 safe_builtin(int idx, int argc, char **argv)
 671 {
 672         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
 673             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
 674             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
 675             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
 676             idx == TYPECMD)
 677                 return (1);
 678         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 679             idx == UMASKCMD)
 680                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 681         if (idx == SETCMD)
 682                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 683                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 684                     argv[1][2] == '\0'));
 685         return (0);
 686 }
 687
 688 /*
 689  * Execute a simple command.
 690  * Note: This may or may not return if (flags & EV_EXIT).
 691  */
 692
 693 static void
 694 evalcommand(union node *cmd, int flgs, struct backcmd *backcmd)
 695 {
 696         struct stackmark smark;
 697         union node *argp;
 698         struct arglist arglist;
 699         struct arglist varlist;
 700         volatile int flags = flgs;
 701         char **volatile argv;
 702         volatile int argc;
 703         char **envp;
 704         int varflag;
 705         struct strlist *sp;
 706         int mode;
 707         int pip[2];
 708         struct cmdentry cmdentry;
 709         struct job *volatile jp;
 710         struct jmploc jmploc;
 711         struct jmploc *savehandler;
 712         const char *savecmdname;
 713         struct shparam saveparam;
 714         struct localvar *savelocalvars;
 715         struct parsefile *savetopfile;
 716         volatile int e;
 717         char *volatile lastarg;
 718         int realstatus;
 719         volatile int do_clearcmdentry;
 720         const char *path = pathval();
 721
 722         /* First expand the arguments. */
 723         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 724         setstackmark(&smark);
 725         arglist.lastp = &arglist.list;
 726         varlist.lastp = &varlist.list;
 727         varflag = 1;
 728         jp = NULL;
 729         do_clearcmdentry = 0;
 730         oexitstatus = exitstatus;
 731         exitstatus = 0;
 732         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 733                 if (varflag && isassignment(argp->narg.text)) {
 734                         expandarg(argp, &varlist, EXP_VARTILDE);
 735                         continue;
 736                 }
 737                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 738                 varflag = 0;
 739         }
 740         *arglist.lastp = NULL;
 741         *varlist.lastp = NULL;
 742         expredir(cmd->ncmd.redirect);
 743         argc = 0;
 744         for (sp = arglist.list ; sp ; sp = sp->next)
 745                 argc++;
 746         /* Add one slot at the beginning for tryexec(). */
 747         argv = stalloc(sizeof (char *) * (argc + 2));
 748         argv++;
 749
 750         for (sp = arglist.list ; sp ; sp = sp->next) {
 751                 TRACE(("evalcommand arg: %s\n", sp->text));
 752                 *argv++ = sp->text;
 753         }
 754         *argv = NULL;
 755         lastarg = NULL;
 756         if (iflag && funcnest == 0 && argc > 0)
 757                 lastarg = argv[-1];
 758         argv -= argc;
 759
 760         /* Print the command if xflag is set. */
 761         if (xflag) {
 762                 char sep = 0;
 763                 const char *p, *ps4;
 764                 ps4 = expandstr(ps4val());
 765                 out2str(ps4 != NULL ? ps4 : ps4val());
 766                 for (sp = varlist.list ; sp ; sp = sp->next) {
 767                         if (sep != 0)
 768                                 out2c(' ');
 769                         p = strchr(sp->text, '=');
 770                         if (p != NULL) {
 771                                 p++;
 772                                 outbin(sp->text, p - sp->text, out2);
 773                                 out2qstr(p);
 774                         } else
 775                                 out2qstr(sp->text);
 776                         sep = ' ';
 777                 }
 778                 for (sp = arglist.list ; sp ; sp = sp->next) {
 779                         if (sep != 0)
 780                                 out2c(' ');
 781                         /* Disambiguate command looking like assignment. */
 782                         if (sp == arglist.list &&
 783                                         strchr(sp->text, '=') != NULL &&
 784                                         strchr(sp->text, '\'') == NULL) {
 785                                 out2c('\'');
 786                                 out2str(sp->text);
 787                                 out2c('\'');
 788                         } else
 789                                 out2qstr(sp->text);
 790                         sep = ' ';
 791                 }
 792                 out2c('\n');
 793                 flushout(&errout);
 794         }
 795
 796         /* Now locate the command. */
 797         if (argc == 0) {
 798                 /* Variable assignment(s) without command */
 799                 cmdentry.cmdtype = CMDBUILTIN;
 800                 cmdentry.u.index = BLTINCMD;
 801                 cmdentry.special = 0;
 802         } else {
 803                 static const char PATH[] = "PATH=";
 804                 int cmd_flags = 0, bltinonly = 0;
 805
 806                 /*
 807                  * Modify the command lookup path, if a PATH= assignment
 808                  * is present
 809                  */
 810                 for (sp = varlist.list ; sp ; sp = sp->next)
 811                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 812                                 path = sp->text + sizeof(PATH) - 1;
 813                                 /*
 814                                  * On `PATH=... command`, we need to make
 815                                  * sure that the command isn't using the
 816                                  * non-updated hash table of the outer PATH
 817                                  * setting and we need to make sure that
 818                                  * the hash table isn't filled with items
 819                                  * from the temporary setting.
 820                                  *
 821                                  * It would be better to forbit using and
 822                                  * updating the table while this command
 823                                  * runs, by the command finding mechanism
 824                                  * is heavily integrated with hash handling,
 825                                  * so we just delete the hash before and after
 826                                  * the command runs. Partly deleting like
 827                                  * changepatch() does doesn't seem worth the
 828                                  * bookinging effort, since most such runs add
 829                                  * directories in front of the new PATH.
 830                                  */
 831                                 clearcmdentry();
 832                                 do_clearcmdentry = 1;
 833                         }
 834
 835                 for (;;) {
 836                         if (bltinonly) {
 837                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 838                                 if (cmdentry.u.index < 0) {
 839                                         cmdentry.u.index = BLTINCMD;
 840                                         argv--;
 841                                         argc++;
 842                                         break;
 843                                 }
 844                         } else
 845                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 846                         /* implement the bltin and command builtins here */
 847                         if (cmdentry.cmdtype != CMDBUILTIN)
 848                                 break;
 849                         if (cmdentry.u.index == BLTINCMD) {
 850                                 if (argc == 1)
 851                                         break;
 852                                 argv++;
 853                                 argc--;
 854                                 bltinonly = 1;
 855                         } else if (cmdentry.u.index == COMMANDCMD) {
 856                                 if (argc == 1)
 857                                         break;
 858                                 if (!strcmp(argv[1], "-p")) {
 859                                         if (argc == 2)
 860                                                 break;
 861                                         if (argv[2][0] == '-') {
 862                                                 if (strcmp(argv[2], "--"))
 863                                                         break;
 864                                                 if (argc == 3)
 865                                                         break;
 866                                                 argv += 3;
 867                                                 argc -= 3;
 868                                         } else {
 869                                                 argv += 2;
 870                                                 argc -= 2;
 871                                         }
 872                                         path = _PATH_STDPATH;
 873                                         clearcmdentry();
 874                                         do_clearcmdentry = 1;
 875                                 } else if (!strcmp(argv[1], "--")) {
 876                                         if (argc == 2)
 877                                                 break;
 878                                         argv += 2;
 879                                         argc -= 2;
 880                                 } else if (argv[1][0] == '-')
 881                                         break;
 882                                 else {
 883                                         argv++;
 884                                         argc--;
 885                                 }
 886                                 cmd_flags |= DO_NOFUNC;
 887                                 bltinonly = 0;
 888                         } else
 889                                 break;
 890                 }
 891                 /*
 892                  * Special builtins lose their special properties when
 893                  * called via 'command'.
 894                  */
 895                 if (cmd_flags & DO_NOFUNC)
 896                         cmdentry.special = 0;
 897         }
 898
 899         /* Fork off a child process if necessary. */
 900         if (cmd->ncmd.backgnd
 901          || ((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 902             && ((flags & EV_EXIT) == 0 || have_traps()))
 903          || ((flags & EV_BACKCMD) != 0
 904             && (cmdentry.cmdtype != CMDBUILTIN ||
 905                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 906                 jp = makejob(cmd, 1);
 907                 mode = cmd->ncmd.backgnd;
 908                 if (flags & EV_BACKCMD) {
 909                         mode = FORK_NOJOB;
 910                         if (pipe(pip) < 0)
 911                                 error("Pipe call failed: %s", strerror(errno));
 912                 }
 913                 if (forkshell(jp, cmd, mode) != 0)
 914                         goto parent;    /* at end of routine */
 915                 if (flags & EV_BACKCMD) {
 916                         FORCEINTON;
 917                         close(pip[0]);
 918                         if (pip[1] != 1) {
 919                                 dup2(pip[1], 1);
 920                                 close(pip[1]);
 921                         }
 922                         flags &= ~EV_BACKCMD;
 923                 }
 924                 flags |= EV_EXIT;
 925         }
 926
 927         /* This is the child process if a fork occurred. */
 928         /* Execute the command. */
 929         if (cmdentry.cmdtype == CMDFUNCTION) {
 930 #ifdef DEBUG
 931                 trputs("Shell function:  ");  trargs(argv);
 932 #endif
 933                 saveparam = shellparam;
 934                 shellparam.malloc = 0;
 935                 shellparam.reset = 1;
 936                 shellparam.nparam = argc - 1;
 937                 shellparam.p = argv + 1;
 938                 shellparam.optnext = NULL;
 939                 INTOFF;
 940                 savelocalvars = localvars;
 941                 localvars = NULL;
 942                 reffunc(cmdentry.u.func);
 943                 savehandler = handler;
 944                 if (setjmp(jmploc.loc)) {
 945                         freeparam(&shellparam);
 946                         shellparam = saveparam;
 947                         popredir();
 948                         unreffunc(cmdentry.u.func);
 949                         poplocalvars();
 950                         localvars = savelocalvars;
 951                         funcnest--;
 952                         handler = savehandler;
 953                         longjmp(handler->loc, 1);
 954                 }
 955                 handler = &jmploc;
 956                 funcnest++;
 957                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
 958                 INTON;
 959                 for (sp = varlist.list ; sp ; sp = sp->next)
 960                         mklocal(sp->text);
 961                 exitstatus = oexitstatus;
 962                 evaltree(getfuncnode(cmdentry.u.func),
 963                     flags & (EV_TESTED | EV_EXIT));
 964                 INTOFF;
 965                 unreffunc(cmdentry.u.func);
 966                 poplocalvars();
 967                 localvars = savelocalvars;
 968                 freeparam(&shellparam);
 969                 shellparam = saveparam;
 970                 handler = savehandler;
 971                 funcnest--;
 972                 popredir();
 973                 INTON;
 974                 if (evalskip == SKIPFUNC) {
 975                         evalskip = 0;
 976                         skipcount = 0;
 977                 }
 978                 if (jp)
 979                         exitshell(exitstatus);
 980         } else if (cmdentry.cmdtype == CMDBUILTIN) {
 981 #ifdef DEBUG
 982                 trputs("builtin command:  ");  trargs(argv);
 983 #endif
 984                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
 985                 if (flags == EV_BACKCMD) {
 986                         memout.nleft = 0;
 987                         memout.nextc = memout.buf;
 988                         memout.bufsize = 64;
 989                         mode |= REDIR_BACKQ;
 990                         cmdentry.special = 0;
 991                 }
 992                 savecmdname = commandname;
 993                 savetopfile = getcurrentfile();
 994                 cmdenviron = varlist.list;
 995                 e = -1;
 996                 savehandler = handler;
 997                 if (setjmp(jmploc.loc)) {
 998                         e = exception;
 999                         if (e == EXINT)
1000                                 exitstatus = SIGINT+128;
1001                         else if (e != EXEXIT)
1002                                 exitstatus = 2;
1003                         goto cmddone;
1004                 }
1005                 handler = &jmploc;
1006                 redirect(cmd->ncmd.redirect, mode);
1007                 /*
1008                  * If there is no command word, redirection errors should
1009                  * not be fatal but assignment errors should.
1010                  */
1011                 if (argc == 0 && !(flags & EV_BACKCMD))
1012                         cmdentry.special = 1;
1013                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1014                 if (argc > 0)
1015                         bltinsetlocale();
1016                 commandname = argv[0];
1017                 argptr = argv + 1;
1018                 nextopt_optptr = NULL;          /* initialize nextopt */
1019                 builtin_flags = flags;
1020                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1021                 flushall();
1022 cmddone:
1023                 if (argc > 0)
1024                         bltinunsetlocale();
1025                 cmdenviron = NULL;
1026                 out1 = &output;
1027                 out2 = &errout;
1028                 freestdout();
1029                 handler = savehandler;
1030                 commandname = savecmdname;
1031                 if (jp)
1032                         exitshell(exitstatus);
1033                 if (flags == EV_BACKCMD) {
1034                         backcmd->buf = memout.buf;
1035                         backcmd->nleft = memout.nextc - memout.buf;
1036                         memout.buf = NULL;
1037                 }
1038                 if (cmdentry.u.index != EXECCMD)
1039                         popredir();
1040                 if (e != -1) {
1041                         if ((e != EXERROR && e != EXEXEC)
1042                             || cmdentry.special)
1043                                 exraise(e);
1044                         popfilesupto(savetopfile);
1045                         if (flags != EV_BACKCMD)
1046                                 FORCEINTON;
1047                 }
1048         } else {
1049 #ifdef DEBUG
1050                 trputs("normal command:  ");  trargs(argv);
1051 #endif
1052                 redirect(cmd->ncmd.redirect, 0);
1053                 for (sp = varlist.list ; sp ; sp = sp->next)
1054                         setvareq(sp->text, VEXPORT|VSTACK);
1055                 envp = environment();
1056                 shellexec(argv, envp, path, cmdentry.u.index);
1057                 /*NOTREACHED*/
1058         }
1059         goto out;
1060
1061 parent: /* parent process gets here (if we forked) */
1062         if (mode == FORK_FG) {  /* argument to fork */
1063                 INTOFF;
1064                 exitstatus = waitforjob(jp, &realstatus);
1065                 INTON;
1066                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1067                         evalskip = SKIPBREAK;
1068                         skipcount = loopnest;
1069                 }
1070         } else if (mode == FORK_NOJOB) {
1071                 backcmd->fd = pip[0];
1072                 close(pip[1]);
1073                 backcmd->jp = jp;
1074         } else
1075                 exitstatus = 0;
1076
1077 out:
1078         if (lastarg)
1079                 setvar("_", lastarg, 0);
1080         if (do_clearcmdentry)
1081                 clearcmdentry();
1082         popstackmark(&smark);
1083 }
1084
1085
1086
1087 /*
1088  * Search for a command.  This is called before we fork so that the
1089  * location of the command will be available in the parent as well as
1090  * the child.  The check for "goodname" is an overly conservative
1091  * check that the name will not be subject to expansion.
1092  */
1093
1094 static void
1095 prehash(union node *n)
1096 {
1097         struct cmdentry entry;
1098
1099         if (n && n->type == NCMD && n->ncmd.args)
1100                 if (goodname(n->ncmd.args->narg.text))
1101                         find_command(n->ncmd.args->narg.text, &entry, 0,
1102                                      pathval());
1103 }
1104
1105
1106
1107 /*
1108  * Builtin commands.  Builtin commands whose functions are closely
1109  * tied to evaluation are implemented here.
1110  */
1111
1112 /*
1113  * No command given, a bltin command with no arguments, or a bltin command
1114  * with an invalid name.
1115  */
1116
1117 int
1118 bltincmd(int argc, char **argv)
1119 {
1120         if (argc > 1) {
1121                 out2fmt_flush("%s: not found\n", argv[1]);
1122                 return 127;
1123         }
1124         /*
1125          * Preserve exitstatus of a previous possible redirection
1126          * as POSIX mandates
1127          */
1128         return exitstatus;
1129 }
1130
1131
1132 /*
1133  * Handle break and continue commands.  Break, continue, and return are
1134  * all handled by setting the evalskip flag.  The evaluation routines
1135  * above all check this flag, and if it is set they start skipping
1136  * commands rather than executing them.  The variable skipcount is
1137  * the number of loops to break/continue, or the number of function
1138  * levels to return.  (The latter is always 1.)  It should probably
1139  * be an error to break out of more loops than exist, but it isn't
1140  * in the standard shell so we don't make it one here.
1141  */
1142
1143 int
1144 breakcmd(int argc, char **argv)
1145 {
1146         int n = argc > 1 ? number(argv[1]) : 1;
1147
1148         if (n > loopnest)
1149                 n = loopnest;
1150         if (n > 0) {
1151                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1152                 skipcount = n;
1153         }
1154         return 0;
1155 }
1156
1157 /*
1158  * The `command' command.
1159  */
1160 int
1161 commandcmd(int argc, char **argv)
1162 {
1163         const char *path;
1164         int ch;
1165         int cmd = -1;
1166
1167         path = bltinlookup("PATH", 1);
1168
1169         optind = optreset = 1;
1170         opterr = 0;
1171         while ((ch = getopt(argc, argv, "pvV")) != -1) {
1172                 switch (ch) {
1173                 case 'p':
1174                         path = _PATH_STDPATH;
1175                         break;
1176                 case 'v':
1177                         cmd = TYPECMD_SMALLV;
1178                         break;
1179                 case 'V':
1180                         cmd = TYPECMD_BIGV;
1181                         break;
1182                 case '?':
1183                 default:
1184                         error("unknown option: -%c", optopt);
1185                 }
1186         }
1187         argc -= optind;
1188         argv += optind;
1189
1190         if (cmd != -1) {
1191                 if (argc != 1)
1192                         error("wrong number of arguments");
1193                 return typecmd_impl(2, argv - 1, cmd, path);
1194         }
1195         if (argc != 0)
1196                 error("commandcmd bad call");
1197
1198         /*
1199          * Do nothing successfully if no command was specified;
1200          * ksh also does this.
1201          */
1202         return(0);
1203 }
1204
1205
1206 /*
1207  * The return command.
1208  */
1209
1210 int
1211 returncmd(int argc, char **argv)
1212 {
1213         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1214
1215         if (funcnest) {
1216                 evalskip = SKIPFUNC;
1217                 skipcount = 1;
1218         } else {
1219                 /* skip the rest of the file */
1220                 evalskip = SKIPFILE;
1221                 skipcount = 1;
1222         }
1223         return ret;
1224 }
1225
1226
1227 int
1228 falsecmd(int argc __unused, char **argv __unused)
1229 {
1230         return 1;
1231 }
1232
1233
1234 int
1235 truecmd(int argc __unused, char **argv __unused)
1236 {
1237         return 0;
1238 }
1239
1240
1241 int
1242 execcmd(int argc, char **argv)
1243 {
1244         /*
1245          * Because we have historically not supported any options,
1246          * only treat "--" specially.
1247          */
1248         if (argc > 1 && strcmp(argv[1], "--") == 0)
1249                 argc--, argv++;
1250         if (argc > 1) {
1251                 struct strlist *sp;
1252
1253                 iflag = 0;              /* exit on error */
1254                 mflag = 0;
1255                 optschanged();
1256                 for (sp = cmdenviron; sp ; sp = sp->next)
1257                         setvareq(sp->text, VEXPORT|VSTACK);
1258                 shellexec(argv + 1, environment(), pathval(), 0);
1259
1260         }
1261         return 0;
1262 }
1263
1264
1265 int
1266 timescmd(int argc __unused, char **argv __unused)
1267 {
1268         struct rusage ru;
1269         long shumins, shsmins, chumins, chsmins;
1270         double shusecs, shssecs, chusecs, chssecs;
1271
1272         if (getrusage(RUSAGE_SELF, &ru) < 0)
1273                 return 1;
1274         shumins = ru.ru_utime.tv_sec / 60;
1275         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1276         shsmins = ru.ru_stime.tv_sec / 60;
1277         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1278         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1279                 return 1;
1280         chumins = ru.ru_utime.tv_sec / 60;
1281         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1282         chsmins = ru.ru_stime.tv_sec / 60;
1283         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1284         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1285             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1286         return 0;
1287 }