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  * 4. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #ifndef lint
  34 #if 0
  35 static char sccsid[] = "@(#)eval.c      8.9 (Berkeley) 6/8/95";
  36 #endif
  37 #endif /* not lint */
  38 #include <sys/cdefs.h>
  39 __FBSDID("$FreeBSD$");
  40
  41 #include <paths.h>
  42 #include <signal.h>
  43 #include <stdlib.h>
  44 #include <unistd.h>
  45 #include <sys/resource.h>
  46 #include <sys/wait.h> /* For WIFSIGNALED(status) */
  47 #include <errno.h>
  48
  49 /*
  50  * Evaluate a command.
  51  */
  52
  53 #include "shell.h"
  54 #include "nodes.h"
  55 #include "syntax.h"
  56 #include "expand.h"
  57 #include "parser.h"
  58 #include "jobs.h"
  59 #include "eval.h"
  60 #include "builtins.h"
  61 #include "options.h"
  62 #include "exec.h"
  63 #include "redir.h"
  64 #include "input.h"
  65 #include "output.h"
  66 #include "trap.h"
  67 #include "var.h"
  68 #include "memalloc.h"
  69 #include "error.h"
  70 #include "show.h"
  71 #include "mystring.h"
  72 #ifndef NO_HISTORY
  73 #include "myhistedit.h"
  74 #endif
  75
  76
  77 int evalskip;                   /* set if we are skipping commands */
  78 int skipcount;                  /* number of levels to skip */
  79 MKINIT int loopnest;            /* current loop nesting level */
  80 int funcnest;                   /* depth of function calls */
  81 static int builtin_flags;       /* evalcommand flags for builtins */
  82
  83
  84 char *commandname;
  85 struct strlist *cmdenviron;
  86 int exitstatus;                 /* exit status of last command */
  87 int oexitstatus;                /* saved exit status */
  88
  89
  90 static void evalloop(union node *, int);
  91 static void evalfor(union node *, int);
  92 static void evalcase(union node *, int);
  93 static void evalsubshell(union node *, int);
  94 static void evalredir(union node *, int);
  95 static void expredir(union node *);
  96 static void evalpipe(union node *);
  97 static int is_valid_fast_cmdsubst(union node *n);
  98 static void evalcommand(union node *, int, struct backcmd *);
  99 static void prehash(union node *);
 100
 101
 102 /*
 103  * Called to reset things after an exception.
 104  */
 105
 106 #ifdef mkinit
 107 INCLUDE "eval.h"
 108
 109 RESET {
 110         evalskip = 0;
 111         loopnest = 0;
 112         funcnest = 0;
 113 }
 114 #endif
 115
 116
 117
 118 /*
 119  * The eval command.
 120  */
 121
 122 int
 123 evalcmd(int argc, char **argv)
 124 {
 125         char *p;
 126         char *concat;
 127         char **ap;
 128
 129         if (argc > 1) {
 130                 p = argv[1];
 131                 if (argc > 2) {
 132                         STARTSTACKSTR(concat);
 133                         ap = argv + 2;
 134                         for (;;) {
 135                                 STPUTS(p, concat);
 136                                 if ((p = *ap++) == NULL)
 137                                         break;
 138                                 STPUTC(' ', concat);
 139                         }
 140                         STPUTC('\0', concat);
 141                         p = grabstackstr(concat);
 142                 }
 143                 evalstring(p, builtin_flags);
 144         } else
 145                 exitstatus = 0;
 146         return exitstatus;
 147 }
 148
 149
 150 /*
 151  * Execute a command or commands contained in a string.
 152  */
 153
 154 void
 155 evalstring(char *s, int flags)
 156 {
 157         union node *n;
 158         struct stackmark smark;
 159         int flags_exit;
 160         int any;
 161
 162         flags_exit = flags & EV_EXIT;
 163         flags &= ~EV_EXIT;
 164         any = 0;
 165         setstackmark(&smark);
 166         setinputstring(s, 1);
 167         while ((n = parsecmd(0)) != NEOF) {
 168                 if (n != NULL && !nflag) {
 169                         if (flags_exit && preadateof())
 170                                 evaltree(n, flags | EV_EXIT);
 171                         else
 172                                 evaltree(n, flags);
 173                         any = 1;
 174                 }
 175                 popstackmark(&smark);
 176         }
 177         popfile();
 178         popstackmark(&smark);
 179         if (!any)
 180                 exitstatus = 0;
 181         if (flags_exit)
 182                 exraise(EXEXIT);
 183 }
 184
 185
 186 /*
 187  * Evaluate a parse tree.  The value is left in the global variable
 188  * exitstatus.
 189  */
 190
 191 void
 192 evaltree(union node *n, int flags)
 193 {
 194         int do_etest;
 195         union node *next;
 196
 197         do_etest = 0;
 198         if (n == NULL) {
 199                 TRACE(("evaltree(NULL) called\n"));
 200                 exitstatus = 0;
 201                 goto out;
 202         }
 203         do {
 204                 next = NULL;
 205 #ifndef NO_HISTORY
 206                 displayhist = 1;        /* show history substitutions done with fc */
 207 #endif
 208                 TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
 209                 switch (n->type) {
 210                 case NSEMI:
 211                         evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
 212                         if (evalskip)
 213                                 goto out;
 214                         next = n->nbinary.ch2;
 215                         break;
 216                 case NAND:
 217                         evaltree(n->nbinary.ch1, EV_TESTED);
 218                         if (evalskip || exitstatus != 0) {
 219                                 goto out;
 220                         }
 221                         next = n->nbinary.ch2;
 222                         break;
 223                 case NOR:
 224                         evaltree(n->nbinary.ch1, EV_TESTED);
 225                         if (evalskip || exitstatus == 0)
 226                                 goto out;
 227                         next = n->nbinary.ch2;
 228                         break;
 229                 case NREDIR:
 230                         evalredir(n, flags);
 231                         break;
 232                 case NSUBSHELL:
 233                         evalsubshell(n, flags);
 234                         do_etest = !(flags & EV_TESTED);
 235                         break;
 236                 case NBACKGND:
 237                         evalsubshell(n, flags);
 238                         break;
 239                 case NIF: {
 240                         evaltree(n->nif.test, EV_TESTED);
 241                         if (evalskip)
 242                                 goto out;
 243                         if (exitstatus == 0)
 244                                 next = n->nif.ifpart;
 245                         else if (n->nif.elsepart)
 246                                 next = n->nif.elsepart;
 247                         else
 248                                 exitstatus = 0;
 249                         break;
 250                 }
 251                 case NWHILE:
 252                 case NUNTIL:
 253                         evalloop(n, flags & ~EV_EXIT);
 254                         break;
 255                 case NFOR:
 256                         evalfor(n, flags & ~EV_EXIT);
 257                         break;
 258                 case NCASE:
 259                         evalcase(n, flags);
 260                         break;
 261                 case NDEFUN:
 262                         defun(n->narg.text, n->narg.next);
 263                         exitstatus = 0;
 264                         break;
 265                 case NNOT:
 266                         evaltree(n->nnot.com, EV_TESTED);
 267                         exitstatus = !exitstatus;
 268                         break;
 269
 270                 case NPIPE:
 271                         evalpipe(n);
 272                         do_etest = !(flags & EV_TESTED);
 273                         break;
 274                 case NCMD:
 275                         evalcommand(n, flags, (struct backcmd *)NULL);
 276                         do_etest = !(flags & EV_TESTED);
 277                         break;
 278                 default:
 279                         out1fmt("Node type = %d\n", n->type);
 280                         flushout(&output);
 281                         break;
 282                 }
 283                 n = next;
 284         } while (n != NULL);
 285 out:
 286         if (pendingsigs)
 287                 dotrap();
 288         if (eflag && exitstatus != 0 && do_etest)
 289                 exitshell(exitstatus);
 290         if (flags & EV_EXIT)
 291                 exraise(EXEXIT);
 292 }
 293
 294
 295 static void
 296 evalloop(union node *n, int flags)
 297 {
 298         int status;
 299
 300         loopnest++;
 301         status = 0;
 302         for (;;) {
 303                 evaltree(n->nbinary.ch1, EV_TESTED);
 304                 if (evalskip) {
 305 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
 306                                 evalskip = 0;
 307                                 continue;
 308                         }
 309                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 310                                 evalskip = 0;
 311                         if (evalskip == SKIPFUNC || evalskip == SKIPFILE)
 312                                 status = exitstatus;
 313                         break;
 314                 }
 315                 if (n->type == NWHILE) {
 316                         if (exitstatus != 0)
 317                                 break;
 318                 } else {
 319                         if (exitstatus == 0)
 320                                 break;
 321                 }
 322                 evaltree(n->nbinary.ch2, flags);
 323                 status = exitstatus;
 324                 if (evalskip)
 325                         goto skipping;
 326         }
 327         loopnest--;
 328         exitstatus = status;
 329 }
 330
 331
 332
 333 static void
 334 evalfor(union node *n, int flags)
 335 {
 336         struct arglist arglist;
 337         union node *argp;
 338         struct strlist *sp;
 339         struct stackmark smark;
 340
 341         setstackmark(&smark);
 342         arglist.lastp = &arglist.list;
 343         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 344                 oexitstatus = exitstatus;
 345                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 346                 if (evalskip)
 347                         goto out;
 348         }
 349         *arglist.lastp = NULL;
 350
 351         exitstatus = 0;
 352         loopnest++;
 353         for (sp = arglist.list ; sp ; sp = sp->next) {
 354                 setvar(n->nfor.var, sp->text, 0);
 355                 evaltree(n->nfor.body, flags);
 356                 if (evalskip) {
 357                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 358                                 evalskip = 0;
 359                                 continue;
 360                         }
 361                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 362                                 evalskip = 0;
 363                         break;
 364                 }
 365         }
 366         loopnest--;
 367 out:
 368         popstackmark(&smark);
 369 }
 370
 371
 372
 373 static void
 374 evalcase(union node *n, int flags)
 375 {
 376         union node *cp;
 377         union node *patp;
 378         struct arglist arglist;
 379         struct stackmark smark;
 380
 381         setstackmark(&smark);
 382         arglist.lastp = &arglist.list;
 383         oexitstatus = exitstatus;
 384         exitstatus = 0;
 385         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 386         for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
 387                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 388                         if (casematch(patp, arglist.list->text)) {
 389                                 while (cp->nclist.next &&
 390                                     cp->type == NCLISTFALLTHRU) {
 391                                         if (evalskip != 0)
 392                                                 break;
 393                                         evaltree(cp->nclist.body,
 394                                             flags & ~EV_EXIT);
 395                                         cp = cp->nclist.next;
 396                                 }
 397                                 if (evalskip == 0) {
 398                                         evaltree(cp->nclist.body, flags);
 399                                 }
 400                                 goto out;
 401                         }
 402                 }
 403         }
 404 out:
 405         popstackmark(&smark);
 406 }
 407
 408
 409
 410 /*
 411  * Kick off a subshell to evaluate a tree.
 412  */
 413
 414 static void
 415 evalsubshell(union node *n, int flags)
 416 {
 417         struct job *jp;
 418         int backgnd = (n->type == NBACKGND);
 419
 420         oexitstatus = exitstatus;
 421         expredir(n->nredir.redirect);
 422         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
 423                         forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
 424                 if (backgnd)
 425                         flags &=~ EV_TESTED;
 426                 redirect(n->nredir.redirect, 0);
 427                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 428         } else if (! backgnd) {
 429                 INTOFF;
 430                 exitstatus = waitforjob(jp, (int *)NULL);
 431                 INTON;
 432         } else
 433                 exitstatus = 0;
 434 }
 435
 436
 437 /*
 438  * Evaluate a redirected compound command.
 439  */
 440
 441 static void
 442 evalredir(union node *n, int flags)
 443 {
 444         struct jmploc jmploc;
 445         struct jmploc *savehandler;
 446         volatile int in_redirect = 1;
 447
 448         oexitstatus = exitstatus;
 449         expredir(n->nredir.redirect);
 450         savehandler = handler;
 451         if (setjmp(jmploc.loc)) {
 452                 int e;
 453
 454                 handler = savehandler;
 455                 e = exception;
 456                 popredir();
 457                 if (e == EXERROR || e == EXEXEC) {
 458                         if (in_redirect) {
 459                                 exitstatus = 2;
 460                                 return;
 461                         }
 462                 }
 463                 longjmp(handler->loc, 1);
 464         } else {
 465                 INTOFF;
 466                 handler = &jmploc;
 467                 redirect(n->nredir.redirect, REDIR_PUSH);
 468                 in_redirect = 0;
 469                 INTON;
 470                 evaltree(n->nredir.n, flags);
 471         }
 472         INTOFF;
 473         handler = savehandler;
 474         popredir();
 475         INTON;
 476 }
 477
 478
 479 /*
 480  * Compute the names of the files in a redirection list.
 481  */
 482
 483 static void
 484 expredir(union node *n)
 485 {
 486         union node *redir;
 487
 488         for (redir = n ; redir ; redir = redir->nfile.next) {
 489                 struct arglist fn;
 490                 fn.lastp = &fn.list;
 491                 switch (redir->type) {
 492                 case NFROM:
 493                 case NTO:
 494                 case NFROMTO:
 495                 case NAPPEND:
 496                 case NCLOBBER:
 497                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 498                         redir->nfile.expfname = fn.list->text;
 499                         break;
 500                 case NFROMFD:
 501                 case NTOFD:
 502                         if (redir->ndup.vname) {
 503                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
 504                                 fixredir(redir, fn.list->text, 1);
 505                         }
 506                         break;
 507                 }
 508         }
 509 }
 510
 511
 512
 513 /*
 514  * Evaluate a pipeline.  All the processes in the pipeline are children
 515  * of the process creating the pipeline.  (This differs from some versions
 516  * of the shell, which make the last process in a pipeline the parent
 517  * of all the rest.)
 518  */
 519
 520 static void
 521 evalpipe(union node *n)
 522 {
 523         struct job *jp;
 524         struct nodelist *lp;
 525         int pipelen;
 526         int prevfd;
 527         int pip[2];
 528
 529         TRACE(("evalpipe(%p) called\n", (void *)n));
 530         pipelen = 0;
 531         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
 532                 pipelen++;
 533         INTOFF;
 534         jp = makejob(n, pipelen);
 535         prevfd = -1;
 536         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
 537                 prehash(lp->n);
 538                 pip[1] = -1;
 539                 if (lp->next) {
 540                         if (pipe(pip) < 0) {
 541                                 close(prevfd);
 542                                 error("Pipe call failed: %s", strerror(errno));
 543                         }
 544                 }
 545                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
 546                         INTON;
 547                         if (prevfd > 0) {
 548                                 dup2(prevfd, 0);
 549                                 close(prevfd);
 550                         }
 551                         if (pip[1] >= 0) {
 552                                 if (!(prevfd >= 0 && pip[0] == 0))
 553                                         close(pip[0]);
 554                                 if (pip[1] != 1) {
 555                                         dup2(pip[1], 1);
 556                                         close(pip[1]);
 557                                 }
 558                         }
 559                         evaltree(lp->n, EV_EXIT);
 560                 }
 561                 if (prevfd >= 0)
 562                         close(prevfd);
 563                 prevfd = pip[0];
 564                 if (pip[1] != -1)
 565                         close(pip[1]);
 566         }
 567         INTON;
 568         if (n->npipe.backgnd == 0) {
 569                 INTOFF;
 570                 exitstatus = waitforjob(jp, (int *)NULL);
 571                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 572                 INTON;
 573         } else
 574                 exitstatus = 0;
 575 }
 576
 577
 578
 579 static int
 580 is_valid_fast_cmdsubst(union node *n)
 581 {
 582
 583         return (n->type == NCMD);
 584 }
 585
 586 /*
 587  * Execute a command inside back quotes.  If it's a builtin command, we
 588  * want to save its output in a block obtained from malloc.  Otherwise
 589  * we fork off a subprocess and get the output of the command via a pipe.
 590  * Should be called with interrupts off.
 591  */
 592
 593 void
 594 evalbackcmd(union node *n, struct backcmd *result)
 595 {
 596         int pip[2];
 597         struct job *jp;
 598         struct stackmark smark;         /* unnecessary */
 599         struct jmploc jmploc;
 600         struct jmploc *savehandler;
 601         struct localvar *savelocalvars;
 602
 603         setstackmark(&smark);
 604         result->fd = -1;
 605         result->buf = NULL;
 606         result->nleft = 0;
 607         result->jp = NULL;
 608         if (n == NULL) {
 609                 exitstatus = 0;
 610                 goto out;
 611         }
 612         if (is_valid_fast_cmdsubst(n)) {
 613                 exitstatus = oexitstatus;
 614                 savelocalvars = localvars;
 615                 localvars = NULL;
 616                 forcelocal++;
 617                 savehandler = handler;
 618                 if (setjmp(jmploc.loc)) {
 619                         if (exception == EXERROR || exception == EXEXEC)
 620                                 exitstatus = 2;
 621                         else if (exception != 0) {
 622                                 handler = savehandler;
 623                                 forcelocal--;
 624                                 poplocalvars();
 625                                 localvars = savelocalvars;
 626                                 longjmp(handler->loc, 1);
 627                         }
 628                 } else {
 629                         handler = &jmploc;
 630                         evalcommand(n, EV_BACKCMD, result);
 631                 }
 632                 handler = savehandler;
 633                 forcelocal--;
 634                 poplocalvars();
 635                 localvars = savelocalvars;
 636         } else {
 637                 exitstatus = 0;
 638                 if (pipe(pip) < 0)
 639                         error("Pipe call failed: %s", strerror(errno));
 640                 jp = makejob(n, 1);
 641                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 642                         FORCEINTON;
 643                         close(pip[0]);
 644                         if (pip[1] != 1) {
 645                                 dup2(pip[1], 1);
 646                                 close(pip[1]);
 647                         }
 648                         evaltree(n, EV_EXIT);
 649                 }
 650                 close(pip[1]);
 651                 result->fd = pip[0];
 652                 result->jp = jp;
 653         }
 654 out:
 655         popstackmark(&smark);
 656         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 657                 result->fd, result->buf, result->nleft, result->jp));
 658 }
 659
 660 /*
 661  * Check if a builtin can safely be executed in the same process,
 662  * even though it should be in a subshell (command substitution).
 663  * Note that jobid, jobs, times and trap can show information not
 664  * available in a child process; this is deliberate.
 665  * The arguments should already have been expanded.
 666  */
 667 static int
 668 safe_builtin(int idx, int argc, char **argv)
 669 {
 670         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
 671             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
 672             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
 673             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
 674             idx == TYPECMD)
 675                 return (1);
 676         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 677             idx == UMASKCMD)
 678                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 679         if (idx == SETCMD)
 680                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 681                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 682                     argv[1][2] == '\0'));
 683         return (0);
 684 }
 685
 686 /*
 687  * Execute a simple command.
 688  * Note: This may or may not return if (flags & EV_EXIT).
 689  */
 690
 691 static void
 692 evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
 693 {
 694         struct stackmark smark;
 695         union node *argp;
 696         struct arglist arglist;
 697         struct arglist varlist;
 698         char **argv;
 699         int argc;
 700         char **envp;
 701         int varflag;
 702         struct strlist *sp;
 703         int mode;
 704         int pip[2];
 705         struct cmdentry cmdentry;
 706         struct job *jp;
 707         struct jmploc jmploc;
 708         struct jmploc *savehandler;
 709         char *savecmdname;
 710         struct shparam saveparam;
 711         struct localvar *savelocalvars;
 712         struct parsefile *savetopfile;
 713         volatile int e;
 714         char *lastarg;
 715         int realstatus;
 716         int do_clearcmdentry;
 717         const char *path = pathval();
 718
 719         /* First expand the arguments. */
 720         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 721         setstackmark(&smark);
 722         arglist.lastp = &arglist.list;
 723         varlist.lastp = &varlist.list;
 724         varflag = 1;
 725         jp = NULL;
 726         do_clearcmdentry = 0;
 727         oexitstatus = exitstatus;
 728         exitstatus = 0;
 729         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 730                 if (varflag && isassignment(argp->narg.text)) {
 731                         expandarg(argp, &varlist, EXP_VARTILDE);
 732                         continue;
 733                 }
 734                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 735                 varflag = 0;
 736         }
 737         *arglist.lastp = NULL;
 738         *varlist.lastp = NULL;
 739         expredir(cmd->ncmd.redirect);
 740         argc = 0;
 741         for (sp = arglist.list ; sp ; sp = sp->next)
 742                 argc++;
 743         /* Add one slot at the beginning for tryexec(). */
 744         argv = stalloc(sizeof (char *) * (argc + 2));
 745         argv++;
 746
 747         for (sp = arglist.list ; sp ; sp = sp->next) {
 748                 TRACE(("evalcommand arg: %s\n", sp->text));
 749                 *argv++ = sp->text;
 750         }
 751         *argv = NULL;
 752         lastarg = NULL;
 753         if (iflag && funcnest == 0 && argc > 0)
 754                 lastarg = argv[-1];
 755         argv -= argc;
 756
 757         /* Print the command if xflag is set. */
 758         if (xflag) {
 759                 char sep = 0;
 760                 const char *p, *ps4;
 761                 ps4 = expandstr(ps4val());
 762                 out2str(ps4 != NULL ? ps4 : ps4val());
 763                 for (sp = varlist.list ; sp ; sp = sp->next) {
 764                         if (sep != 0)
 765                                 out2c(' ');
 766                         p = strchr(sp->text, '=');
 767                         if (p != NULL) {
 768                                 p++;
 769                                 outbin(sp->text, p - sp->text, out2);
 770                                 out2qstr(p);
 771                         } else
 772                                 out2qstr(sp->text);
 773                         sep = ' ';
 774                 }
 775                 for (sp = arglist.list ; sp ; sp = sp->next) {
 776                         if (sep != 0)
 777                                 out2c(' ');
 778                         /* Disambiguate command looking like assignment. */
 779                         if (sp == arglist.list &&
 780                                         strchr(sp->text, '=') != NULL &&
 781                                         strchr(sp->text, '\'') == NULL) {
 782                                 out2c('\'');
 783                                 out2str(sp->text);
 784                                 out2c('\'');
 785                         } else
 786                                 out2qstr(sp->text);
 787                         sep = ' ';
 788                 }
 789                 out2c('\n');
 790                 flushout(&errout);
 791         }
 792
 793         /* Now locate the command. */
 794         if (argc == 0) {
 795                 /* Variable assignment(s) without command */
 796                 cmdentry.cmdtype = CMDBUILTIN;
 797                 cmdentry.u.index = BLTINCMD;
 798                 cmdentry.special = 0;
 799         } else {
 800                 static const char PATH[] = "PATH=";
 801                 int cmd_flags = 0, bltinonly = 0;
 802
 803                 /*
 804                  * Modify the command lookup path, if a PATH= assignment
 805                  * is present
 806                  */
 807                 for (sp = varlist.list ; sp ; sp = sp->next)
 808                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 809                                 path = sp->text + sizeof(PATH) - 1;
 810                                 /*
 811                                  * On `PATH=... command`, we need to make
 812                                  * sure that the command isn't using the
 813                                  * non-updated hash table of the outer PATH
 814                                  * setting and we need to make sure that
 815                                  * the hash table isn't filled with items
 816                                  * from the temporary setting.
 817                                  *
 818                                  * It would be better to forbit using and
 819                                  * updating the table while this command
 820                                  * runs, by the command finding mechanism
 821                                  * is heavily integrated with hash handling,
 822                                  * so we just delete the hash before and after
 823                                  * the command runs. Partly deleting like
 824                                  * changepatch() does doesn't seem worth the
 825                                  * bookinging effort, since most such runs add
 826                                  * directories in front of the new PATH.
 827                                  */
 828                                 clearcmdentry();
 829                                 do_clearcmdentry = 1;
 830                         }
 831
 832                 for (;;) {
 833                         if (bltinonly) {
 834                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 835                                 if (cmdentry.u.index < 0) {
 836                                         cmdentry.u.index = BLTINCMD;
 837                                         argv--;
 838                                         argc++;
 839                                         break;
 840                                 }
 841                         } else
 842                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 843                         /* implement the bltin and command builtins here */
 844                         if (cmdentry.cmdtype != CMDBUILTIN)
 845                                 break;
 846                         if (cmdentry.u.index == BLTINCMD) {
 847                                 if (argc == 1)
 848                                         break;
 849                                 argv++;
 850                                 argc--;
 851                                 bltinonly = 1;
 852                         } else if (cmdentry.u.index == COMMANDCMD) {
 853                                 if (argc == 1)
 854                                         break;
 855                                 if (!strcmp(argv[1], "-p")) {
 856                                         if (argc == 2)
 857                                                 break;
 858                                         if (argv[2][0] == '-') {
 859                                                 if (strcmp(argv[2], "--"))
 860                                                         break;
 861                                                 if (argc == 3)
 862                                                         break;
 863                                                 argv += 3;
 864                                                 argc -= 3;
 865                                         } else {
 866                                                 argv += 2;
 867                                                 argc -= 2;
 868                                         }
 869                                         path = _PATH_STDPATH;
 870                                         clearcmdentry();
 871                                         do_clearcmdentry = 1;
 872                                 } else if (!strcmp(argv[1], "--")) {
 873                                         if (argc == 2)
 874                                                 break;
 875                                         argv += 2;
 876                                         argc -= 2;
 877                                 } else if (argv[1][0] == '-')
 878                                         break;
 879                                 else {
 880                                         argv++;
 881                                         argc--;
 882                                 }
 883                                 cmd_flags |= DO_NOFUNC;
 884                                 bltinonly = 0;
 885                         } else
 886                                 break;
 887                 }
 888                 /*
 889                  * Special builtins lose their special properties when
 890                  * called via 'command'.
 891                  */
 892                 if (cmd_flags & DO_NOFUNC)
 893                         cmdentry.special = 0;
 894         }
 895
 896         /* Fork off a child process if necessary. */
 897         if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 898             && ((flags & EV_EXIT) == 0 || have_traps()))
 899          || ((flags & EV_BACKCMD) != 0
 900             && (cmdentry.cmdtype != CMDBUILTIN ||
 901                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 902                 jp = makejob(cmd, 1);
 903                 mode = FORK_FG;
 904                 if (flags & EV_BACKCMD) {
 905                         mode = FORK_NOJOB;
 906                         if (pipe(pip) < 0)
 907                                 error("Pipe call failed: %s", strerror(errno));
 908                 }
 909                 if (cmdentry.cmdtype == CMDNORMAL &&
 910                     cmd->ncmd.redirect == NULL &&
 911                     varlist.list == NULL &&
 912                     (mode == FORK_FG || mode == FORK_NOJOB) &&
 913                     !disvforkset() && !iflag && !mflag) {
 914                         vforkexecshell(jp, argv, environment(), path,
 915                             cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL);
 916                         goto parent;
 917                 }
 918                 if (forkshell(jp, cmd, mode) != 0)
 919                         goto parent;    /* at end of routine */
 920                 if (flags & EV_BACKCMD) {
 921                         FORCEINTON;
 922                         close(pip[0]);
 923                         if (pip[1] != 1) {
 924                                 dup2(pip[1], 1);
 925                                 close(pip[1]);
 926                         }
 927                         flags &= ~EV_BACKCMD;
 928                 }
 929                 flags |= EV_EXIT;
 930         }
 931
 932         /* This is the child process if a fork occurred. */
 933         /* Execute the command. */
 934         if (cmdentry.cmdtype == CMDFUNCTION) {
 935 #ifdef DEBUG
 936                 trputs("Shell function:  ");  trargs(argv);
 937 #endif
 938                 saveparam = shellparam;
 939                 shellparam.malloc = 0;
 940                 shellparam.reset = 1;
 941                 shellparam.nparam = argc - 1;
 942                 shellparam.p = argv + 1;
 943                 shellparam.optnext = NULL;
 944                 INTOFF;
 945                 savelocalvars = localvars;
 946                 localvars = NULL;
 947                 reffunc(cmdentry.u.func);
 948                 savehandler = handler;
 949                 if (setjmp(jmploc.loc)) {
 950                         freeparam(&shellparam);
 951                         shellparam = saveparam;
 952                         popredir();
 953                         unreffunc(cmdentry.u.func);
 954                         poplocalvars();
 955                         localvars = savelocalvars;
 956                         funcnest--;
 957                         handler = savehandler;
 958                         longjmp(handler->loc, 1);
 959                 }
 960                 handler = &jmploc;
 961                 funcnest++;
 962                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
 963                 INTON;
 964                 for (sp = varlist.list ; sp ; sp = sp->next)
 965                         mklocal(sp->text);
 966                 exitstatus = oexitstatus;
 967                 evaltree(getfuncnode(cmdentry.u.func),
 968                     flags & (EV_TESTED | EV_EXIT));
 969                 INTOFF;
 970                 unreffunc(cmdentry.u.func);
 971                 poplocalvars();
 972                 localvars = savelocalvars;
 973                 freeparam(&shellparam);
 974                 shellparam = saveparam;
 975                 handler = savehandler;
 976                 funcnest--;
 977                 popredir();
 978                 INTON;
 979                 if (evalskip == SKIPFUNC) {
 980                         evalskip = 0;
 981                         skipcount = 0;
 982                 }
 983                 if (jp)
 984                         exitshell(exitstatus);
 985         } else if (cmdentry.cmdtype == CMDBUILTIN) {
 986 #ifdef DEBUG
 987                 trputs("builtin command:  ");  trargs(argv);
 988 #endif
 989                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
 990                 if (flags == EV_BACKCMD) {
 991                         memout.nleft = 0;
 992                         memout.nextc = memout.buf;
 993                         memout.bufsize = 64;
 994                         mode |= REDIR_BACKQ;
 995                 }
 996                 savecmdname = commandname;
 997                 savetopfile = getcurrentfile();
 998                 cmdenviron = varlist.list;
 999                 e = -1;
1000                 savehandler = handler;
1001                 if (setjmp(jmploc.loc)) {
1002                         e = exception;
1003                         if (e == EXINT)
1004                                 exitstatus = SIGINT+128;
1005                         else if (e != EXEXIT)
1006                                 exitstatus = 2;
1007                         goto cmddone;
1008                 }
1009                 handler = &jmploc;
1010                 redirect(cmd->ncmd.redirect, mode);
1011                 /*
1012                  * If there is no command word, redirection errors should
1013                  * not be fatal but assignment errors should.
1014                  */
1015                 if (argc == 0)
1016                         cmdentry.special = 1;
1017                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1018                 if (argc > 0)
1019                         bltinsetlocale();
1020                 commandname = argv[0];
1021                 argptr = argv + 1;
1022                 nextopt_optptr = NULL;          /* initialize nextopt */
1023                 builtin_flags = flags;
1024                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1025                 flushall();
1026 cmddone:
1027                 if (argc > 0)
1028                         bltinunsetlocale();
1029                 cmdenviron = NULL;
1030                 out1 = &output;
1031                 out2 = &errout;
1032                 freestdout();
1033                 handler = savehandler;
1034                 commandname = savecmdname;
1035                 if (jp)
1036                         exitshell(exitstatus);
1037                 if (flags == EV_BACKCMD) {
1038                         backcmd->buf = memout.buf;
1039                         backcmd->nleft = memout.nextc - memout.buf;
1040                         memout.buf = NULL;
1041                 }
1042                 if (cmdentry.u.index != EXECCMD)
1043                         popredir();
1044                 if (e != -1) {
1045                         if ((e != EXERROR && e != EXEXEC)
1046                             || cmdentry.special)
1047                                 exraise(e);
1048                         popfilesupto(savetopfile);
1049                         if (flags != EV_BACKCMD)
1050                                 FORCEINTON;
1051                 }
1052         } else {
1053 #ifdef DEBUG
1054                 trputs("normal command:  ");  trargs(argv);
1055 #endif
1056                 redirect(cmd->ncmd.redirect, 0);
1057                 for (sp = varlist.list ; sp ; sp = sp->next)
1058                         setvareq(sp->text, VEXPORT|VSTACK);
1059                 envp = environment();
1060                 shellexec(argv, envp, path, cmdentry.u.index);
1061                 /*NOTREACHED*/
1062         }
1063         goto out;
1064
1065 parent: /* parent process gets here (if we forked) */
1066         if (mode == FORK_FG) {  /* argument to fork */
1067                 INTOFF;
1068                 exitstatus = waitforjob(jp, &realstatus);
1069                 INTON;
1070                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1071                         evalskip = SKIPBREAK;
1072                         skipcount = loopnest;
1073                 }
1074         } else if (mode == FORK_NOJOB) {
1075                 backcmd->fd = pip[0];
1076                 close(pip[1]);
1077                 backcmd->jp = jp;
1078         }
1079
1080 out:
1081         if (lastarg)
1082                 setvar("_", lastarg, 0);
1083         if (do_clearcmdentry)
1084                 clearcmdentry();
1085         popstackmark(&smark);
1086 }
1087
1088
1089
1090 /*
1091  * Search for a command.  This is called before we fork so that the
1092  * location of the command will be available in the parent as well as
1093  * the child.  The check for "goodname" is an overly conservative
1094  * check that the name will not be subject to expansion.
1095  */
1096
1097 static void
1098 prehash(union node *n)
1099 {
1100         struct cmdentry entry;
1101
1102         if (n && n->type == NCMD && n->ncmd.args)
1103                 if (goodname(n->ncmd.args->narg.text))
1104                         find_command(n->ncmd.args->narg.text, &entry, 0,
1105                                      pathval());
1106 }
1107
1108
1109
1110 /*
1111  * Builtin commands.  Builtin commands whose functions are closely
1112  * tied to evaluation are implemented here.
1113  */
1114
1115 /*
1116  * No command given, a bltin command with no arguments, or a bltin command
1117  * with an invalid name.
1118  */
1119
1120 int
1121 bltincmd(int argc, char **argv)
1122 {
1123         if (argc > 1) {
1124                 out2fmt_flush("%s: not found\n", argv[1]);
1125                 return 127;
1126         }
1127         /*
1128          * Preserve exitstatus of a previous possible redirection
1129          * as POSIX mandates
1130          */
1131         return exitstatus;
1132 }
1133
1134
1135 /*
1136  * Handle break and continue commands.  Break, continue, and return are
1137  * all handled by setting the evalskip flag.  The evaluation routines
1138  * above all check this flag, and if it is set they start skipping
1139  * commands rather than executing them.  The variable skipcount is
1140  * the number of loops to break/continue, or the number of function
1141  * levels to return.  (The latter is always 1.)  It should probably
1142  * be an error to break out of more loops than exist, but it isn't
1143  * in the standard shell so we don't make it one here.
1144  */
1145
1146 int
1147 breakcmd(int argc, char **argv)
1148 {
1149         int n = argc > 1 ? number(argv[1]) : 1;
1150
1151         if (n > loopnest)
1152                 n = loopnest;
1153         if (n > 0) {
1154                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1155                 skipcount = n;
1156         }
1157         return 0;
1158 }
1159
1160 /*
1161  * The `command' command.
1162  */
1163 int
1164 commandcmd(int argc, char **argv)
1165 {
1166         const char *path;
1167         int ch;
1168         int cmd = -1;
1169
1170         path = bltinlookup("PATH", 1);
1171
1172         optind = optreset = 1;
1173         opterr = 0;
1174         while ((ch = getopt(argc, argv, "pvV")) != -1) {
1175                 switch (ch) {
1176                 case 'p':
1177                         path = _PATH_STDPATH;
1178                         break;
1179                 case 'v':
1180                         cmd = TYPECMD_SMALLV;
1181                         break;
1182                 case 'V':
1183                         cmd = TYPECMD_BIGV;
1184                         break;
1185                 case '?':
1186                 default:
1187                         error("unknown option: -%c", optopt);
1188                 }
1189         }
1190         argc -= optind;
1191         argv += optind;
1192
1193         if (cmd != -1) {
1194                 if (argc != 1)
1195                         error("wrong number of arguments");
1196                 return typecmd_impl(2, argv - 1, cmd, path);
1197         }
1198         if (argc != 0)
1199                 error("commandcmd bad call");
1200
1201         /*
1202          * Do nothing successfully if no command was specified;
1203          * ksh also does this.
1204          */
1205         return 0;
1206 }
1207
1208
1209 /*
1210  * The return command.
1211  */
1212
1213 int
1214 returncmd(int argc, char **argv)
1215 {
1216         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1217
1218         if (funcnest) {
1219                 evalskip = SKIPFUNC;
1220                 skipcount = 1;
1221         } else {
1222                 /* skip the rest of the file */
1223                 evalskip = SKIPFILE;
1224                 skipcount = 1;
1225         }
1226         return ret;
1227 }
1228
1229
1230 int
1231 falsecmd(int argc __unused, char **argv __unused)
1232 {
1233         return 1;
1234 }
1235
1236
1237 int
1238 truecmd(int argc __unused, char **argv __unused)
1239 {
1240         return 0;
1241 }
1242
1243
1244 int
1245 execcmd(int argc, char **argv)
1246 {
1247         /*
1248          * Because we have historically not supported any options,
1249          * only treat "--" specially.
1250          */
1251         if (argc > 1 && strcmp(argv[1], "--") == 0)
1252                 argc--, argv++;
1253         if (argc > 1) {
1254                 struct strlist *sp;
1255
1256                 iflag = 0;              /* exit on error */
1257                 mflag = 0;
1258                 optschanged();
1259                 for (sp = cmdenviron; sp ; sp = sp->next)
1260                         setvareq(sp->text, VEXPORT|VSTACK);
1261                 shellexec(argv + 1, environment(), pathval(), 0);
1262
1263         }
1264         return 0;
1265 }
1266
1267
1268 int
1269 timescmd(int argc __unused, char **argv __unused)
1270 {
1271         struct rusage ru;
1272         long shumins, shsmins, chumins, chsmins;
1273         double shusecs, shssecs, chusecs, chssecs;
1274
1275         if (getrusage(RUSAGE_SELF, &ru) < 0)
1276                 return 1;
1277         shumins = ru.ru_utime.tv_sec / 60;
1278         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1279         shsmins = ru.ru_stime.tv_sec / 60;
1280         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1281         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1282                 return 1;
1283         chumins = ru.ru_utime.tv_sec / 60;
1284         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1285         chsmins = ru.ru_stime.tv_sec / 60;
1286         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1287         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1288             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1289         return 0;
1290 }