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 1.117 2012/01/15 21:39:38 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 union node *evalcase(union node *);
  94 static void evalsubshell(union node *, int);
  95 static void evalredir(union node *, int);
  96 static void expredir(union node *);
  97 static void evalpipe(union node *);
  98 static int is_valid_fast_cmdsubst(union node *n);
  99 static void evalcommand(union node *, int, struct backcmd *);
 100 static void prehash(union node *);
 101
 102
 103 /*
 104  * Called to reset things after an exception.
 105  */
 106
 107 #ifdef mkinit
 108 INCLUDE "eval.h"
 109
 110 RESET {
 111         evalskip = 0;
 112         loopnest = 0;
 113         funcnest = 0;
 114 }
 115 #endif
 116
 117
 118
 119 /*
 120  * The eval command.
 121  */
 122
 123 int
 124 evalcmd(int argc, char **argv)
 125 {
 126         char *p;
 127         char *concat;
 128         char **ap;
 129
 130         if (argc > 1) {
 131                 p = argv[1];
 132                 if (argc > 2) {
 133                         STARTSTACKSTR(concat);
 134                         ap = argv + 2;
 135                         for (;;) {
 136                                 STPUTS(p, concat);
 137                                 if ((p = *ap++) == NULL)
 138                                         break;
 139                                 STPUTC(' ', concat);
 140                         }
 141                         STPUTC('\0', concat);
 142                         p = grabstackstr(concat);
 143                 }
 144                 evalstring(p, builtin_flags);
 145         } else
 146                 exitstatus = 0;
 147         return exitstatus;
 148 }
 149
 150
 151 /*
 152  * Execute a command or commands contained in a string.
 153  */
 154
 155 void
 156 evalstring(char *s, int flags)
 157 {
 158         union node *n;
 159         struct stackmark smark;
 160         int flags_exit;
 161         int any;
 162
 163         flags_exit = flags & EV_EXIT;
 164         flags &= ~EV_EXIT;
 165         any = 0;
 166         setstackmark(&smark);
 167         setinputstring(s, 1);
 168         while ((n = parsecmd(0)) != NEOF) {
 169                 if (n != NULL && !nflag) {
 170                         if (flags_exit && preadateof())
 171                                 evaltree(n, flags | EV_EXIT);
 172                         else
 173                                 evaltree(n, flags);
 174                         any = 1;
 175                 }
 176                 popstackmark(&smark);
 177         }
 178         popfile();
 179         popstackmark(&smark);
 180         if (!any)
 181                 exitstatus = 0;
 182         if (flags_exit)
 183                 exraise(EXEXIT);
 184 }
 185
 186
 187 /*
 188  * Evaluate a parse tree.  The value is left in the global variable
 189  * exitstatus.
 190  */
 191
 192 void
 193 evaltree(union node *n, int flags)
 194 {
 195         int do_etest;
 196         union node *next;
 197
 198         do_etest = 0;
 199         if (n == NULL) {
 200                 TRACE(("evaltree(NULL) called\n"));
 201                 exitstatus = 0;
 202                 goto out;
 203         }
 204         do {
 205                 next = NULL;
 206 #ifndef NO_HISTORY
 207                 displayhist = 1;        /* show history substitutions done with fc */
 208 #endif
 209                 TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
 210                 switch (n->type) {
 211                 case NSEMI:
 212                         evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
 213                         if (evalskip)
 214                                 goto out;
 215                         next = n->nbinary.ch2;
 216                         break;
 217                 case NAND:
 218                         evaltree(n->nbinary.ch1, EV_TESTED);
 219                         if (evalskip || exitstatus != 0) {
 220                                 goto out;
 221                         }
 222                         next = n->nbinary.ch2;
 223                         break;
 224                 case NOR:
 225                         evaltree(n->nbinary.ch1, EV_TESTED);
 226                         if (evalskip || exitstatus == 0)
 227                                 goto out;
 228                         next = n->nbinary.ch2;
 229                         break;
 230                 case NREDIR:
 231                         evalredir(n, flags);
 232                         break;
 233                 case NSUBSHELL:
 234                         evalsubshell(n, flags);
 235                         do_etest = !(flags & EV_TESTED);
 236                         break;
 237                 case NBACKGND:
 238                         evalsubshell(n, flags);
 239                         break;
 240                 case NIF: {
 241                         evaltree(n->nif.test, EV_TESTED);
 242                         if (evalskip)
 243                                 goto out;
 244                         if (exitstatus == 0)
 245                                 next = n->nif.ifpart;
 246                         else if (n->nif.elsepart)
 247                                 next = n->nif.elsepart;
 248                         else
 249                                 exitstatus = 0;
 250                         break;
 251                 }
 252                 case NWHILE:
 253                 case NUNTIL:
 254                         evalloop(n, flags & ~EV_EXIT);
 255                         break;
 256                 case NFOR:
 257                         evalfor(n, flags & ~EV_EXIT);
 258                         break;
 259                 case NCASE:
 260                         next = evalcase(n);
 261                         break;
 262                 case NCLIST:
 263                         next = n->nclist.body;
 264                         break;
 265                 case NCLISTFALLTHRU:
 266                         if (n->nclist.body) {
 267                                 evaltree(n->nclist.body, flags & ~EV_EXIT);
 268                                 if (evalskip)
 269                                         goto out;
 270                         }
 271                         next = n->nclist.next;
 272                         break;
 273                 case NDEFUN:
 274                         defun(n->narg.text, n->narg.next);
 275                         exitstatus = 0;
 276                         break;
 277                 case NNOT:
 278                         evaltree(n->nnot.com, EV_TESTED);
 279                         exitstatus = !exitstatus;
 280                         break;
 281
 282                 case NPIPE:
 283                         evalpipe(n);
 284                         do_etest = !(flags & EV_TESTED);
 285                         break;
 286                 case NCMD:
 287                         evalcommand(n, flags, NULL);
 288                         do_etest = !(flags & EV_TESTED);
 289                         break;
 290                 default:
 291                         out1fmt("Node type = %d\n", n->type);
 292                         flushout(&output);
 293                         break;
 294                 }
 295                 n = next;
 296         } while (n != NULL);
 297 out:
 298         if (pendingsigs)
 299                 dotrap();
 300         if (eflag && exitstatus != 0 && do_etest)
 301                 exitshell(exitstatus);
 302         if (flags & EV_EXIT)
 303                 exraise(EXEXIT);
 304 }
 305
 306
 307 static void
 308 evalloop(union node *n, int flags)
 309 {
 310         int status;
 311
 312         loopnest++;
 313         status = 0;
 314         for (;;) {
 315                 evaltree(n->nbinary.ch1, EV_TESTED);
 316                 if (evalskip) {
 317 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
 318                                 evalskip = 0;
 319                                 continue;
 320                         }
 321                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 322                                 evalskip = 0;
 323                         if (evalskip == SKIPFUNC || evalskip == SKIPFILE)
 324                                 status = exitstatus;
 325                         break;
 326                 }
 327                 if (n->type == NWHILE) {
 328                         if (exitstatus != 0)
 329                                 break;
 330                 } else {
 331                         if (exitstatus == 0)
 332                                 break;
 333                 }
 334                 evaltree(n->nbinary.ch2, flags);
 335                 status = exitstatus;
 336                 if (evalskip)
 337                         goto skipping;
 338         }
 339         loopnest--;
 340         exitstatus = status;
 341 }
 342
 343
 344
 345 static void
 346 evalfor(union node *n, int flags)
 347 {
 348         struct arglist arglist;
 349         union node *argp;
 350         struct strlist *sp;
 351         struct stackmark smark;
 352
 353         setstackmark(&smark);
 354         arglist.lastp = &arglist.list;
 355         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 356                 oexitstatus = exitstatus;
 357                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 358         }
 359         *arglist.lastp = NULL;
 360
 361         exitstatus = 0;
 362         loopnest++;
 363         for (sp = arglist.list ; sp ; sp = sp->next) {
 364                 setvar(n->nfor.var, sp->text, 0);
 365                 evaltree(n->nfor.body, flags);
 366                 if (evalskip) {
 367                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 368                                 evalskip = 0;
 369                                 continue;
 370                         }
 371                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 372                                 evalskip = 0;
 373                         break;
 374                 }
 375         }
 376         loopnest--;
 377         popstackmark(&smark);
 378 }
 379
 380
 381 /*
 382  * Evaluate a case statement, returning the selected tree.
 383  *
 384  * The exit status needs care to get right.
 385  */
 386
 387 static union node *
 388 evalcase(union node *n)
 389 {
 390         union node *cp;
 391         union node *patp;
 392         struct arglist arglist;
 393         struct stackmark smark;
 394
 395         setstackmark(&smark);
 396         arglist.lastp = &arglist.list;
 397         oexitstatus = exitstatus;
 398         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 399         for (cp = n->ncase.cases ; cp ; cp = cp->nclist.next) {
 400                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 401                         if (casematch(patp, arglist.list->text)) {
 402                                 popstackmark(&smark);
 403                                 while (cp->nclist.next &&
 404                                     cp->type == NCLISTFALLTHRU &&
 405                                     cp->nclist.body == NULL)
 406                                         cp = cp->nclist.next;
 407                                 if (cp->nclist.next &&
 408                                     cp->type == NCLISTFALLTHRU)
 409                                         return (cp);
 410                                 if (cp->nclist.body == NULL)
 411                                         exitstatus = 0;
 412                                 return (cp->nclist.body);
 413                         }
 414                 }
 415         }
 416         popstackmark(&smark);
 417         exitstatus = 0;
 418         return (NULL);
 419 }
 420
 421
 422
 423 /*
 424  * Kick off a subshell to evaluate a tree.
 425  */
 426
 427 static void
 428 evalsubshell(union node *n, int flags)
 429 {
 430         struct job *jp;
 431         int backgnd = (n->type == NBACKGND);
 432
 433         oexitstatus = exitstatus;
 434         expredir(n->nredir.redirect);
 435         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
 436             forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
 437                 if (backgnd)
 438                         flags &=~ EV_TESTED;
 439                 redirect(n->nredir.redirect, 0);
 440                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 441         } else if (!backgnd) {
 442                 INTOFF;
 443                 exitstatus = waitforjob(jp, NULL);
 444                 INTON;
 445         } else
 446                 exitstatus = 0;
 447 }
 448
 449
 450 /*
 451  * Evaluate a redirected compound command.
 452  */
 453
 454 static void
 455 evalredir(union node *n, int flags)
 456 {
 457         struct jmploc jmploc;
 458         struct jmploc *savehandler;
 459         volatile int in_redirect = 1;
 460
 461         oexitstatus = exitstatus;
 462         expredir(n->nredir.redirect);
 463         savehandler = handler;
 464         if (setjmp(jmploc.loc)) {
 465                 int e;
 466
 467                 handler = savehandler;
 468                 e = exception;
 469                 popredir();
 470                 if (e == EXERROR || e == EXEXEC) {
 471                         if (in_redirect) {
 472                                 exitstatus = 2;
 473                                 return;
 474                         }
 475                 }
 476                 longjmp(handler->loc, 1);
 477         } else {
 478                 INTOFF;
 479                 handler = &jmploc;
 480                 redirect(n->nredir.redirect, REDIR_PUSH);
 481                 in_redirect = 0;
 482                 INTON;
 483                 evaltree(n->nredir.n, flags);
 484         }
 485         INTOFF;
 486         handler = savehandler;
 487         popredir();
 488         INTON;
 489 }
 490
 491
 492 /*
 493  * Compute the names of the files in a redirection list.
 494  */
 495
 496 static void
 497 expredir(union node *n)
 498 {
 499         union node *redir;
 500
 501         for (redir = n ; redir ; redir = redir->nfile.next) {
 502                 struct arglist fn;
 503                 fn.lastp = &fn.list;
 504                 switch (redir->type) {
 505                 case NFROM:
 506                 case NTO:
 507                 case NFROMTO:
 508                 case NAPPEND:
 509                 case NCLOBBER:
 510                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 511                         redir->nfile.expfname = fn.list->text;
 512                         break;
 513                 case NFROMFD:
 514                 case NTOFD:
 515                         if (redir->ndup.vname) {
 516                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
 517                                 fixredir(redir, fn.list->text, 1);
 518                         }
 519                         break;
 520                 }
 521         }
 522 }
 523
 524
 525
 526 /*
 527  * Evaluate a pipeline.  All the processes in the pipeline are children
 528  * of the process creating the pipeline.  (This differs from some versions
 529  * of the shell, which make the last process in a pipeline the parent
 530  * of all the rest.)
 531  */
 532
 533 static void
 534 evalpipe(union node *n)
 535 {
 536         struct job *jp;
 537         struct nodelist *lp;
 538         int pipelen;
 539         int prevfd;
 540         int pip[2];
 541
 542         TRACE(("evalpipe(%p) called\n", (void *)n));
 543         pipelen = 0;
 544         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
 545                 pipelen++;
 546         INTOFF;
 547         jp = makejob(n, pipelen);
 548         prevfd = -1;
 549         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
 550                 prehash(lp->n);
 551                 pip[1] = -1;
 552                 if (lp->next) {
 553                         if (pipe(pip) < 0) {
 554                                 if (prevfd >= 0)
 555                                         close(prevfd);
 556                                 error("Pipe call failed: %s", strerror(errno));
 557                         }
 558                 }
 559                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
 560                         INTON;
 561                         if (prevfd > 0) {
 562                                 dup2(prevfd, 0);
 563                                 close(prevfd);
 564                         }
 565                         if (pip[1] >= 0) {
 566                                 if (!(prevfd >= 0 && pip[0] == 0))
 567                                         close(pip[0]);
 568                                 if (pip[1] != 1) {
 569                                         dup2(pip[1], 1);
 570                                         close(pip[1]);
 571                                 }
 572                         }
 573                         evaltree(lp->n, EV_EXIT);
 574                 }
 575                 if (prevfd >= 0)
 576                         close(prevfd);
 577                 prevfd = pip[0];
 578                 if (pip[1] != -1)
 579                         close(pip[1]);
 580         }
 581         INTON;
 582         if (n->npipe.backgnd == 0) {
 583                 INTOFF;
 584                 exitstatus = waitforjob(jp, NULL);
 585                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 586                 INTON;
 587         } else
 588                 exitstatus = 0;
 589 }
 590
 591
 592
 593 static int
 594 is_valid_fast_cmdsubst(union node *n)
 595 {
 596
 597         return (n->type == NCMD);
 598 }
 599
 600 /*
 601  * Execute a command inside back quotes.  If it's a builtin command, we
 602  * want to save its output in a block obtained from malloc.  Otherwise
 603  * we fork off a subprocess and get the output of the command via a pipe.
 604  * Should be called with interrupts off.
 605  */
 606
 607 void
 608 evalbackcmd(union node *n, struct backcmd *result)
 609 {
 610         int pip[2];
 611         struct job *jp;
 612         struct stackmark smark;         /* unnecessary */
 613         struct jmploc jmploc;
 614         struct jmploc *savehandler;
 615         struct localvar *savelocalvars;
 616
 617         setstackmark(&smark);
 618         result->fd = -1;
 619         result->buf = NULL;
 620         result->nleft = 0;
 621         result->jp = NULL;
 622         if (n == NULL) {
 623                 exitstatus = 0;
 624                 goto out;
 625         }
 626         if (is_valid_fast_cmdsubst(n)) {
 627                 exitstatus = oexitstatus;
 628                 savelocalvars = localvars;
 629                 localvars = NULL;
 630                 forcelocal++;
 631                 savehandler = handler;
 632                 if (setjmp(jmploc.loc)) {
 633                         if (exception == EXERROR || exception == EXEXEC)
 634                                 exitstatus = 2;
 635                         else if (exception != 0) {
 636                                 handler = savehandler;
 637                                 forcelocal--;
 638                                 poplocalvars();
 639                                 localvars = savelocalvars;
 640                                 longjmp(handler->loc, 1);
 641                         }
 642                 } else {
 643                         handler = &jmploc;
 644                         evalcommand(n, EV_BACKCMD, result);
 645                 }
 646                 handler = savehandler;
 647                 forcelocal--;
 648                 poplocalvars();
 649                 localvars = savelocalvars;
 650         } else {
 651                 exitstatus = 0;
 652                 if (pipe(pip) < 0)
 653                         error("Pipe call failed: %s", strerror(errno));
 654                 jp = makejob(n, 1);
 655                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 656                         FORCEINTON;
 657                         close(pip[0]);
 658                         if (pip[1] != 1) {
 659                                 dup2(pip[1], 1);
 660                                 close(pip[1]);
 661                         }
 662                         evaltree(n, EV_EXIT);
 663                 }
 664                 close(pip[1]);
 665                 result->fd = pip[0];
 666                 result->jp = jp;
 667         }
 668 out:
 669         popstackmark(&smark);
 670         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 671                 result->fd, result->buf, result->nleft, result->jp));
 672 }
 673
 674 /*
 675  * Check if a builtin can safely be executed in the same process,
 676  * even though it should be in a subshell (command substitution).
 677  * Note that jobid, jobs, times and trap can show information not
 678  * available in a child process; this is deliberate.
 679  * The arguments should already have been expanded.
 680  */
 681 static int
 682 safe_builtin(int idx, int argc, char **argv)
 683 {
 684         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
 685             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
 686             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
 687             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
 688             idx == TYPECMD)
 689                 return (1);
 690         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 691             idx == UMASKCMD)
 692                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 693         if (idx == SETCMD)
 694                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 695                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 696                     argv[1][2] == '\0'));
 697         return (0);
 698 }
 699
 700 /*
 701  * Execute a simple command.
 702  * Note: This may or may not return if (flags & EV_EXIT).
 703  */
 704
 705 static void
 706 evalcommand(union node *cmd, int flgs, struct backcmd *backcmd)
 707 {
 708         struct stackmark smark;
 709         union node *argp;
 710         struct arglist arglist;
 711         struct arglist varlist;
 712         volatile int flags = flgs;
 713         char **volatile argv;
 714         volatile int argc;
 715         char **envp;
 716         int varflag;
 717         struct strlist *sp;
 718         int mode;
 719         int pip[2];
 720         struct cmdentry cmdentry;
 721         struct job *volatile jp;
 722         struct jmploc jmploc;
 723         struct jmploc *savehandler;
 724         const char *savecmdname;
 725         struct shparam saveparam;
 726         struct localvar *savelocalvars;
 727         struct parsefile *savetopfile;
 728         volatile int e;
 729         char *volatile lastarg;
 730         int realstatus;
 731         volatile int do_clearcmdentry;
 732         const char *path = pathval();
 733
 734         /* First expand the arguments. */
 735         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 736         setstackmark(&smark);
 737         arglist.lastp = &arglist.list;
 738         varlist.lastp = &varlist.list;
 739         varflag = 1;
 740         jp = NULL;
 741         do_clearcmdentry = 0;
 742         oexitstatus = exitstatus;
 743         exitstatus = 0;
 744         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 745                 if (varflag && isassignment(argp->narg.text)) {
 746                         expandarg(argp, &varlist, EXP_VARTILDE);
 747                         continue;
 748                 }
 749                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 750                 varflag = 0;
 751         }
 752         *arglist.lastp = NULL;
 753         *varlist.lastp = NULL;
 754         expredir(cmd->ncmd.redirect);
 755         argc = 0;
 756         for (sp = arglist.list ; sp ; sp = sp->next)
 757                 argc++;
 758         /* Add one slot at the beginning for tryexec(). */
 759         argv = stalloc(sizeof (char *) * (argc + 2));
 760         argv++;
 761
 762         for (sp = arglist.list ; sp ; sp = sp->next) {
 763                 TRACE(("evalcommand arg: %s\n", sp->text));
 764                 *argv++ = sp->text;
 765         }
 766         *argv = NULL;
 767         lastarg = NULL;
 768         if (iflag && funcnest == 0 && argc > 0)
 769                 lastarg = argv[-1];
 770         argv -= argc;
 771
 772         /* Print the command if xflag is set. */
 773         if (xflag) {
 774                 char sep = 0;
 775                 const char *p, *ps4;
 776                 ps4 = expandstr(ps4val());
 777                 out2str(ps4 != NULL ? ps4 : ps4val());
 778                 for (sp = varlist.list ; sp ; sp = sp->next) {
 779                         if (sep != 0)
 780                                 out2c(' ');
 781                         p = strchr(sp->text, '=');
 782                         if (p != NULL) {
 783                                 p++;
 784                                 outbin(sp->text, p - sp->text, out2);
 785                                 out2qstr(p);
 786                         } else
 787                                 out2qstr(sp->text);
 788                         sep = ' ';
 789                 }
 790                 for (sp = arglist.list ; sp ; sp = sp->next) {
 791                         if (sep != 0)
 792                                 out2c(' ');
 793                         /* Disambiguate command looking like assignment. */
 794                         if (sp == arglist.list &&
 795                                         strchr(sp->text, '=') != NULL &&
 796                                         strchr(sp->text, '\'') == NULL) {
 797                                 out2c('\'');
 798                                 out2str(sp->text);
 799                                 out2c('\'');
 800                         } else
 801                                 out2qstr(sp->text);
 802                         sep = ' ';
 803                 }
 804                 out2c('\n');
 805                 flushout(&errout);
 806         }
 807
 808         /* Now locate the command. */
 809         if (argc == 0) {
 810                 /* Variable assignment(s) without command */
 811                 cmdentry.cmdtype = CMDBUILTIN;
 812                 cmdentry.u.index = BLTINCMD;
 813                 cmdentry.special = 0;
 814         } else {
 815                 static const char PATH[] = "PATH=";
 816                 int cmd_flags = 0, bltinonly = 0;
 817
 818                 /*
 819                  * Modify the command lookup path, if a PATH= assignment
 820                  * is present
 821                  */
 822                 for (sp = varlist.list ; sp ; sp = sp->next)
 823                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 824                                 path = sp->text + sizeof(PATH) - 1;
 825                                 /*
 826                                  * On `PATH=... command`, we need to make
 827                                  * sure that the command isn't using the
 828                                  * non-updated hash table of the outer PATH
 829                                  * setting and we need to make sure that
 830                                  * the hash table isn't filled with items
 831                                  * from the temporary setting.
 832                                  *
 833                                  * It would be better to forbit using and
 834                                  * updating the table while this command
 835                                  * runs, by the command finding mechanism
 836                                  * is heavily integrated with hash handling,
 837                                  * so we just delete the hash before and after
 838                                  * the command runs. Partly deleting like
 839                                  * changepatch() does doesn't seem worth the
 840                                  * bookinging effort, since most such runs add
 841                                  * directories in front of the new PATH.
 842                                  */
 843                                 clearcmdentry();
 844                                 do_clearcmdentry = 1;
 845                         }
 846
 847                 for (;;) {
 848                         if (bltinonly) {
 849                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 850                                 if (cmdentry.u.index < 0) {
 851                                         cmdentry.u.index = BLTINCMD;
 852                                         argv--;
 853                                         argc++;
 854                                         break;
 855                                 }
 856                         } else
 857                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 858                         /* implement the bltin and command builtins here */
 859                         if (cmdentry.cmdtype != CMDBUILTIN)
 860                                 break;
 861                         if (cmdentry.u.index == BLTINCMD) {
 862                                 if (argc == 1)
 863                                         break;
 864                                 argv++;
 865                                 argc--;
 866                                 bltinonly = 1;
 867                         } else if (cmdentry.u.index == COMMANDCMD) {
 868                                 if (argc == 1)
 869                                         break;
 870                                 if (!strcmp(argv[1], "-p")) {
 871                                         if (argc == 2)
 872                                                 break;
 873                                         if (argv[2][0] == '-') {
 874                                                 if (strcmp(argv[2], "--"))
 875                                                         break;
 876                                                 if (argc == 3)
 877                                                         break;
 878                                                 argv += 3;
 879                                                 argc -= 3;
 880                                         } else {
 881                                                 argv += 2;
 882                                                 argc -= 2;
 883                                         }
 884                                         path = _PATH_STDPATH;
 885                                         clearcmdentry();
 886                                         do_clearcmdentry = 1;
 887                                 } else if (!strcmp(argv[1], "--")) {
 888                                         if (argc == 2)
 889                                                 break;
 890                                         argv += 2;
 891                                         argc -= 2;
 892                                 } else if (argv[1][0] == '-')
 893                                         break;
 894                                 else {
 895                                         argv++;
 896                                         argc--;
 897                                 }
 898                                 cmd_flags |= DO_NOFUNC;
 899                                 bltinonly = 0;
 900                         } else
 901                                 break;
 902                 }
 903                 /*
 904                  * Special builtins lose their special properties when
 905                  * called via 'command'.
 906                  */
 907                 if (cmd_flags & DO_NOFUNC)
 908                         cmdentry.special = 0;
 909         }
 910
 911         /* Fork off a child process if necessary. */
 912         if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 913             && ((flags & EV_EXIT) == 0 || have_traps()))
 914          || ((flags & EV_BACKCMD) != 0
 915             && (cmdentry.cmdtype != CMDBUILTIN ||
 916                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 917                 jp = makejob(cmd, 1);
 918                 mode = FORK_FG;
 919                 if (flags & EV_BACKCMD) {
 920                         mode = FORK_NOJOB;
 921                         if (pipe(pip) < 0)
 922                                 error("Pipe call failed: %s", strerror(errno));
 923                 }
 924                 if (forkshell(jp, cmd, mode) != 0)
 925                         goto parent;    /* at end of routine */
 926                 if (flags & EV_BACKCMD) {
 927                         FORCEINTON;
 928                         close(pip[0]);
 929                         if (pip[1] != 1) {
 930                                 dup2(pip[1], 1);
 931                                 close(pip[1]);
 932                         }
 933                         flags &= ~EV_BACKCMD;
 934                 }
 935                 flags |= EV_EXIT;
 936         }
 937
 938         /* This is the child process if a fork occurred. */
 939         /* Execute the command. */
 940         if (cmdentry.cmdtype == CMDFUNCTION) {
 941 #ifdef DEBUG
 942                 trputs("Shell function:  ");  trargs(argv);
 943 #endif
 944                 saveparam = shellparam;
 945                 shellparam.malloc = 0;
 946                 shellparam.reset = 1;
 947                 shellparam.nparam = argc - 1;
 948                 shellparam.p = argv + 1;
 949                 shellparam.optnext = NULL;
 950                 INTOFF;
 951                 savelocalvars = localvars;
 952                 localvars = NULL;
 953                 reffunc(cmdentry.u.func);
 954                 savehandler = handler;
 955                 if (setjmp(jmploc.loc)) {
 956                         freeparam(&shellparam);
 957                         shellparam = saveparam;
 958                         popredir();
 959                         unreffunc(cmdentry.u.func);
 960                         poplocalvars();
 961                         localvars = savelocalvars;
 962                         funcnest--;
 963                         handler = savehandler;
 964                         longjmp(handler->loc, 1);
 965                 }
 966                 handler = &jmploc;
 967                 funcnest++;
 968                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
 969                 INTON;
 970                 for (sp = varlist.list ; sp ; sp = sp->next)
 971                         mklocal(sp->text);
 972                 exitstatus = oexitstatus;
 973                 evaltree(getfuncnode(cmdentry.u.func),
 974                     flags & (EV_TESTED | EV_EXIT));
 975                 INTOFF;
 976                 unreffunc(cmdentry.u.func);
 977                 poplocalvars();
 978                 localvars = savelocalvars;
 979                 freeparam(&shellparam);
 980                 shellparam = saveparam;
 981                 handler = savehandler;
 982                 funcnest--;
 983                 popredir();
 984                 INTON;
 985                 if (evalskip == SKIPFUNC) {
 986                         evalskip = 0;
 987                         skipcount = 0;
 988                 }
 989                 if (jp)
 990                         exitshell(exitstatus);
 991         } else if (cmdentry.cmdtype == CMDBUILTIN) {
 992 #ifdef DEBUG
 993                 trputs("builtin command:  ");  trargs(argv);
 994 #endif
 995                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
 996                 if (flags == EV_BACKCMD) {
 997                         memout.nleft = 0;
 998                         memout.nextc = memout.buf;
 999                         memout.bufsize = 64;
1000                         mode |= REDIR_BACKQ;
1001                 }
1002                 savecmdname = commandname;
1003                 savetopfile = getcurrentfile();
1004                 cmdenviron = varlist.list;
1005                 e = -1;
1006                 savehandler = handler;
1007                 if (setjmp(jmploc.loc)) {
1008                         e = exception;
1009                         if (e == EXINT)
1010                                 exitstatus = SIGINT+128;
1011                         else if (e != EXEXIT)
1012                                 exitstatus = 2;
1013                         goto cmddone;
1014                 }
1015                 handler = &jmploc;
1016                 redirect(cmd->ncmd.redirect, mode);
1017                 /*
1018                  * If there is no command word, redirection errors should
1019                  * not be fatal but assignment errors should.
1020                  */
1021                 if (argc == 0)
1022                         cmdentry.special = 1;
1023                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1024                 if (argc > 0)
1025                         bltinsetlocale();
1026                 commandname = argv[0];
1027                 argptr = argv + 1;
1028                 nextopt_optptr = NULL;          /* initialize nextopt */
1029                 builtin_flags = flags;
1030                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1031                 flushall();
1032 cmddone:
1033                 if (argc > 0)
1034                         bltinunsetlocale();
1035                 cmdenviron = NULL;
1036                 out1 = &output;
1037                 out2 = &errout;
1038                 freestdout();
1039                 handler = savehandler;
1040                 commandname = savecmdname;
1041                 if (jp)
1042                         exitshell(exitstatus);
1043                 if (flags == EV_BACKCMD) {
1044                         backcmd->buf = memout.buf;
1045                         backcmd->nleft = memout.nextc - memout.buf;
1046                         memout.buf = NULL;
1047                 }
1048                 if (cmdentry.u.index != EXECCMD)
1049                         popredir();
1050                 if (e != -1) {
1051                         if ((e != EXERROR && e != EXEXEC)
1052                             || cmdentry.special)
1053                                 exraise(e);
1054                         popfilesupto(savetopfile);
1055                         if (flags != EV_BACKCMD)
1056                                 FORCEINTON;
1057                 }
1058         } else {
1059 #ifdef DEBUG
1060                 trputs("normal command:  ");  trargs(argv);
1061 #endif
1062                 redirect(cmd->ncmd.redirect, 0);
1063                 for (sp = varlist.list ; sp ; sp = sp->next)
1064                         setvareq(sp->text, VEXPORT|VSTACK);
1065                 envp = environment();
1066                 shellexec(argv, envp, path, cmdentry.u.index);
1067                 /*NOTREACHED*/
1068         }
1069         goto out;
1070
1071 parent: /* parent process gets here (if we forked) */
1072         if (mode == FORK_FG) {  /* argument to fork */
1073                 INTOFF;
1074                 exitstatus = waitforjob(jp, &realstatus);
1075                 INTON;
1076                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1077                         evalskip = SKIPBREAK;
1078                         skipcount = loopnest;
1079                 }
1080         } else if (mode == FORK_NOJOB) {
1081                 backcmd->fd = pip[0];
1082                 close(pip[1]);
1083                 backcmd->jp = jp;
1084         }
1085
1086 out:
1087         if (lastarg)
1088                 setvar("_", lastarg, 0);
1089         if (do_clearcmdentry)
1090                 clearcmdentry();
1091         popstackmark(&smark);
1092 }
1093
1094
1095
1096 /*
1097  * Search for a command.  This is called before we fork so that the
1098  * location of the command will be available in the parent as well as
1099  * the child.  The check for "goodname" is an overly conservative
1100  * check that the name will not be subject to expansion.
1101  */
1102
1103 static void
1104 prehash(union node *n)
1105 {
1106         struct cmdentry entry;
1107
1108         if (n && n->type == NCMD && n->ncmd.args)
1109                 if (goodname(n->ncmd.args->narg.text))
1110                         find_command(n->ncmd.args->narg.text, &entry, 0,
1111                                      pathval());
1112 }
1113
1114
1115
1116 /*
1117  * Builtin commands.  Builtin commands whose functions are closely
1118  * tied to evaluation are implemented here.
1119  */
1120
1121 /*
1122  * No command given, a bltin command with no arguments, or a bltin command
1123  * with an invalid name.
1124  */
1125
1126 int
1127 bltincmd(int argc, char **argv)
1128 {
1129         if (argc > 1) {
1130                 out2fmt_flush("%s: not found\n", argv[1]);
1131                 return 127;
1132         }
1133         /*
1134          * Preserve exitstatus of a previous possible redirection
1135          * as POSIX mandates
1136          */
1137         return exitstatus;
1138 }
1139
1140
1141 /*
1142  * Handle break and continue commands.  Break, continue, and return are
1143  * all handled by setting the evalskip flag.  The evaluation routines
1144  * above all check this flag, and if it is set they start skipping
1145  * commands rather than executing them.  The variable skipcount is
1146  * the number of loops to break/continue, or the number of function
1147  * levels to return.  (The latter is always 1.)  It should probably
1148  * be an error to break out of more loops than exist, but it isn't
1149  * in the standard shell so we don't make it one here.
1150  */
1151
1152 int
1153 breakcmd(int argc, char **argv)
1154 {
1155         int n = argc > 1 ? number(argv[1]) : 1;
1156
1157         if (n > loopnest)
1158                 n = loopnest;
1159         if (n > 0) {
1160                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1161                 skipcount = n;
1162         }
1163         return 0;
1164 }
1165
1166 /*
1167  * The `command' command.
1168  */
1169 int
1170 commandcmd(int argc, char **argv)
1171 {
1172         const char *path;
1173         int ch;
1174         int cmd = -1;
1175
1176         path = bltinlookup("PATH", 1);
1177
1178         optind = optreset = 1;
1179         opterr = 0;
1180         while ((ch = getopt(argc, argv, "pvV")) != -1) {
1181                 switch (ch) {
1182                 case 'p':
1183                         path = _PATH_STDPATH;
1184                         break;
1185                 case 'v':
1186                         cmd = TYPECMD_SMALLV;
1187                         break;
1188                 case 'V':
1189                         cmd = TYPECMD_BIGV;
1190                         break;
1191                 case '?':
1192                 default:
1193                         error("unknown option: -%c", optopt);
1194                 }
1195         }
1196         argc -= optind;
1197         argv += optind;
1198
1199         if (cmd != -1) {
1200                 if (argc != 1)
1201                         error("wrong number of arguments");
1202                 return typecmd_impl(2, argv - 1, cmd, path);
1203         }
1204         if (argc != 0)
1205                 error("commandcmd bad call");
1206
1207         /*
1208          * Do nothing successfully if no command was specified;
1209          * ksh also does this.
1210          */
1211         return(0);
1212 }
1213
1214
1215 /*
1216  * The return command.
1217  */
1218
1219 int
1220 returncmd(int argc, char **argv)
1221 {
1222         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1223
1224         if (funcnest) {
1225                 evalskip = SKIPFUNC;
1226                 skipcount = 1;
1227         } else {
1228                 /* skip the rest of the file */
1229                 evalskip = SKIPFILE;
1230                 skipcount = 1;
1231         }
1232         return ret;
1233 }
1234
1235
1236 int
1237 falsecmd(int argc __unused, char **argv __unused)
1238 {
1239         return 1;
1240 }
1241
1242
1243 int
1244 truecmd(int argc __unused, char **argv __unused)
1245 {
1246         return 0;
1247 }
1248
1249
1250 int
1251 execcmd(int argc, char **argv)
1252 {
1253         /*
1254          * Because we have historically not supported any options,
1255          * only treat "--" specially.
1256          */
1257         if (argc > 1 && strcmp(argv[1], "--") == 0)
1258                 argc--, argv++;
1259         if (argc > 1) {
1260                 struct strlist *sp;
1261
1262                 iflag = 0;              /* exit on error */
1263                 mflag = 0;
1264                 optschanged();
1265                 for (sp = cmdenviron; sp ; sp = sp->next)
1266                         setvareq(sp->text, VEXPORT|VSTACK);
1267                 shellexec(argv + 1, environment(), pathval(), 0);
1268
1269         }
1270         return 0;
1271 }
1272
1273
1274 int
1275 timescmd(int argc __unused, char **argv __unused)
1276 {
1277         struct rusage ru;
1278         long shumins, shsmins, chumins, chsmins;
1279         double shusecs, shssecs, chusecs, chssecs;
1280
1281         if (getrusage(RUSAGE_SELF, &ru) < 0)
1282                 return 1;
1283         shumins = ru.ru_utime.tv_sec / 60;
1284         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1285         shsmins = ru.ru_stime.tv_sec / 60;
1286         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1287         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1288                 return 1;
1289         chumins = ru.ru_utime.tv_sec / 60;
1290         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1291         chsmins = ru.ru_stime.tv_sec / 60;
1292         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1293         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1294             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1295         return 0;
1296 }