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