bin/sh/eval.c

   1 /*-
   2  * Copyright (c) 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Kenneth Almquist.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 4. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #ifndef lint
  34 #if 0
  35 static char sccsid[] = "@(#)eval.c      8.9 (Berkeley) 6/8/95";
  36 #endif
  37 #endif /* not lint */
  38 #include <sys/cdefs.h>
  39 __FBSDID("$FreeBSD$");
  40
  41 #include <paths.h>
  42 #include <signal.h>
  43 #include <stdlib.h>
  44 #include <unistd.h>
  45 #include <sys/resource.h>
  46 #include <sys/wait.h> /* For WIFSIGNALED(status) */
  47 #include <errno.h>
  48
  49 /*
  50  * Evaluate a command.
  51  */
  52
  53 #include "shell.h"
  54 #include "nodes.h"
  55 #include "syntax.h"
  56 #include "expand.h"
  57 #include "parser.h"
  58 #include "jobs.h"
  59 #include "eval.h"
  60 #include "builtins.h"
  61 #include "options.h"
  62 #include "exec.h"
  63 #include "redir.h"
  64 #include "input.h"
  65 #include "output.h"
  66 #include "trap.h"
  67 #include "var.h"
  68 #include "memalloc.h"
  69 #include "error.h"
  70 #include "show.h"
  71 #include "mystring.h"
  72 #ifndef NO_HISTORY
  73 #include "myhistedit.h"
  74 #endif
  75
  76
  77 int evalskip;                   /* set if we are skipping commands */
  78 int skipcount;                  /* number of levels to skip */
  79 MKINIT int loopnest;            /* current loop nesting level */
  80 int funcnest;                   /* depth of function calls */
  81 static int builtin_flags;       /* evalcommand flags for builtins */
  82
  83
  84 char *commandname;
  85 struct strlist *cmdenviron;
  86 int exitstatus;                 /* exit status of last command */
  87 int oexitstatus;                /* saved exit status */
  88
  89
  90 static void evalloop(union node *, int);
  91 static void evalfor(union node *, int);
  92 static void evalcase(union node *, int);
  93 static void evalsubshell(union node *, int);
  94 static void evalredir(union node *, int);
  95 static void expredir(union node *);
  96 static void evalpipe(union node *);
  97 static int is_valid_fast_cmdsubst(union node *n);
  98 static void evalcommand(union node *, int, struct backcmd *);
  99 static void prehash(union node *);
 100
 101
 102 /*
 103  * Called to reset things after an exception.
 104  */
 105
 106 #ifdef mkinit
 107 INCLUDE "eval.h"
 108
 109 RESET {
 110         evalskip = 0;
 111         loopnest = 0;
 112         funcnest = 0;
 113 }
 114 #endif
 115
 116
 117
 118 /*
 119  * The eval command.
 120  */
 121
 122 int
 123 evalcmd(int argc, char **argv)
 124 {
 125         char *p;
 126         char *concat;
 127         char **ap;
 128
 129         if (argc > 1) {
 130                 p = argv[1];
 131                 if (argc > 2) {
 132                         STARTSTACKSTR(concat);
 133                         ap = argv + 2;
 134                         for (;;) {
 135                                 STPUTS(p, concat);
 136                                 if ((p = *ap++) == NULL)
 137                                         break;
 138                                 STPUTC(' ', concat);
 139                         }
 140                         STPUTC('\0', concat);
 141                         p = grabstackstr(concat);
 142                 }
 143                 evalstring(p, builtin_flags);
 144         } else
 145                 exitstatus = 0;
 146         return exitstatus;
 147 }
 148
 149
 150 /*
 151  * Execute a command or commands contained in a string.
 152  */
 153
 154 void
 155 evalstring(char *s, int flags)
 156 {
 157         union node *n;
 158         struct stackmark smark;
 159         int flags_exit;
 160         int any;
 161
 162         flags_exit = flags & EV_EXIT;
 163         flags &= ~EV_EXIT;
 164         any = 0;
 165         setstackmark(&smark);
 166         setinputstring(s, 1);
 167         while ((n = parsecmd(0)) != NEOF) {
 168                 if (n != NULL && !nflag) {
 169                         if (flags_exit && preadateof())
 170                                 evaltree(n, flags | EV_EXIT);
 171                         else
 172                                 evaltree(n, flags);
 173                         any = 1;
 174                 }
 175                 popstackmark(&smark);
 176         }
 177         popfile();
 178         popstackmark(&smark);
 179         if (!any)
 180                 exitstatus = 0;
 181         if (flags_exit)
 182                 exraise(EXEXIT);
 183 }
 184
 185
 186 /*
 187  * Evaluate a parse tree.  The value is left in the global variable
 188  * exitstatus.
 189  */
 190
 191 void
 192 evaltree(union node *n, int flags)
 193 {
 194         int do_etest;
 195         union node *next;
 196
 197         do_etest = 0;
 198         if (n == NULL) {
 199                 TRACE(("evaltree(NULL) called\n"));
 200                 exitstatus = 0;
 201                 goto out;
 202         }
 203         do {
 204                 next = NULL;
 205 #ifndef NO_HISTORY
 206                 displayhist = 1;        /* show history substitutions done with fc */
 207 #endif
 208                 TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
 209                 switch (n->type) {
 210                 case NSEMI:
 211                         evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
 212                         if (evalskip)
 213                                 goto out;
 214                         next = n->nbinary.ch2;
 215                         break;
 216                 case NAND:
 217                         evaltree(n->nbinary.ch1, EV_TESTED);
 218                         if (evalskip || exitstatus != 0) {
 219                                 goto out;
 220                         }
 221                         next = n->nbinary.ch2;
 222                         break;
 223                 case NOR:
 224                         evaltree(n->nbinary.ch1, EV_TESTED);
 225                         if (evalskip || exitstatus == 0)
 226                                 goto out;
 227                         next = n->nbinary.ch2;
 228                         break;
 229                 case NREDIR:
 230                         evalredir(n, flags);
 231                         break;
 232                 case NSUBSHELL:
 233                         evalsubshell(n, flags);
 234                         do_etest = !(flags & EV_TESTED);
 235                         break;
 236                 case NBACKGND:
 237                         evalsubshell(n, flags);
 238                         break;
 239                 case NIF: {
 240                         evaltree(n->nif.test, EV_TESTED);
 241                         if (evalskip)
 242                                 goto out;
 243                         if (exitstatus == 0)
 244                                 next = n->nif.ifpart;
 245                         else if (n->nif.elsepart)
 246                                 next = n->nif.elsepart;
 247                         else
 248                                 exitstatus = 0;
 249                         break;
 250                 }
 251                 case NWHILE:
 252                 case NUNTIL:
 253                         evalloop(n, flags & ~EV_EXIT);
 254                         break;
 255                 case NFOR:
 256                         evalfor(n, flags & ~EV_EXIT);
 257                         break;
 258                 case NCASE:
 259                         evalcase(n, flags);
 260                         break;
 261                 case NDEFUN:
 262                         defun(n->narg.text, n->narg.next);
 263                         exitstatus = 0;
 264                         break;
 265                 case NNOT:
 266                         evaltree(n->nnot.com, EV_TESTED);
 267                         exitstatus = !exitstatus;
 268                         break;
 269
 270                 case NPIPE:
 271                         evalpipe(n);
 272                         do_etest = !(flags & EV_TESTED);
 273                         break;
 274                 case NCMD:
 275                         evalcommand(n, flags, (struct backcmd *)NULL);
 276                         do_etest = !(flags & EV_TESTED);
 277                         break;
 278                 default:
 279                         out1fmt("Node type = %d\n", n->type);
 280                         flushout(&output);
 281                         break;
 282                 }
 283                 n = next;
 284         } while (n != NULL);
 285 out:
 286         if (pendingsigs)
 287                 dotrap();
 288         if (eflag && exitstatus != 0 && do_etest)
 289                 exitshell(exitstatus);
 290         if (flags & EV_EXIT)
 291                 exraise(EXEXIT);
 292 }
 293
 294
 295 static void
 296 evalloop(union node *n, int flags)
 297 {
 298         int status;
 299
 300         loopnest++;
 301         status = 0;
 302         for (;;) {
 303                 evaltree(n->nbinary.ch1, EV_TESTED);
 304                 if (evalskip) {
 305 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
 306                                 evalskip = 0;
 307                                 continue;
 308                         }
 309                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 310                                 evalskip = 0;
 311                         if (evalskip == SKIPFUNC || evalskip == SKIPFILE)
 312                                 status = exitstatus;
 313                         break;
 314                 }
 315                 if (n->type == NWHILE) {
 316                         if (exitstatus != 0)
 317                                 break;
 318                 } else {
 319                         if (exitstatus == 0)
 320                                 break;
 321                 }
 322                 evaltree(n->nbinary.ch2, flags);
 323                 status = exitstatus;
 324                 if (evalskip)
 325                         goto skipping;
 326         }
 327         loopnest--;
 328         exitstatus = status;
 329 }
 330
 331
 332
 333 static void
 334 evalfor(union node *n, int flags)
 335 {
 336         struct arglist arglist;
 337         union node *argp;
 338         struct strlist *sp;
 339         struct stackmark smark;
 340
 341         setstackmark(&smark);
 342         arglist.lastp = &arglist.list;
 343         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 344                 oexitstatus = exitstatus;
 345                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 346                 if (evalskip)
 347                         goto out;
 348         }
 349         *arglist.lastp = NULL;
 350
 351         exitstatus = 0;
 352         loopnest++;
 353         for (sp = arglist.list ; sp ; sp = sp->next) {
 354                 setvar(n->nfor.var, sp->text, 0);
 355                 evaltree(n->nfor.body, flags);
 356                 if (evalskip) {
 357                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 358                                 evalskip = 0;
 359                                 continue;
 360                         }
 361                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 362                                 evalskip = 0;
 363                         break;
 364                 }
 365         }
 366         loopnest--;
 367 out:
 368         popstackmark(&smark);
 369 }
 370
 371
 372
 373 static void
 374 evalcase(union node *n, int flags)
 375 {
 376         union node *cp;
 377         union node *patp;
 378         struct arglist arglist;
 379         struct stackmark smark;
 380
 381         setstackmark(&smark);
 382         arglist.lastp = &arglist.list;
 383         oexitstatus = exitstatus;
 384         exitstatus = 0;
 385         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 386         for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
 387                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 388                         if (casematch(patp, arglist.list->text)) {
 389                                 while (cp->nclist.next &&
 390                                     cp->type == NCLISTFALLTHRU) {
 391                                         if (evalskip != 0)
 392                                                 break;
 393                                         evaltree(cp->nclist.body,
 394                                             flags & ~EV_EXIT);
 395                                         cp = cp->nclist.next;
 396                                 }
 397                                 if (evalskip == 0) {
 398                                         evaltree(cp->nclist.body, flags);
 399                                 }
 400                                 goto out;
 401                         }
 402                 }
 403         }
 404 out:
 405         popstackmark(&smark);
 406 }
 407
 408
 409
 410 /*
 411  * Kick off a subshell to evaluate a tree.
 412  */
 413
 414 static void
 415 evalsubshell(union node *n, int flags)
 416 {
 417         struct job *jp;
 418         int backgnd = (n->type == NBACKGND);
 419
 420         oexitstatus = exitstatus;
 421         expredir(n->nredir.redirect);
 422         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
 423                         forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
 424                 if (backgnd)
 425                         flags &=~ EV_TESTED;
 426                 redirect(n->nredir.redirect, 0);
 427                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 428         } else if (! backgnd) {
 429                 INTOFF;
 430                 exitstatus = waitforjob(jp, (int *)NULL);
 431                 INTON;
 432         } else
 433                 exitstatus = 0;
 434 }
 435
 436
 437 /*
 438  * Evaluate a redirected compound command.
 439  */
 440
 441 static void
 442 evalredir(union node *n, int flags)
 443 {
 444         struct jmploc jmploc;
 445         struct jmploc *savehandler;
 446         volatile int in_redirect = 1;
 447
 448         oexitstatus = exitstatus;
 449         expredir(n->nredir.redirect);
 450         savehandler = handler;
 451         if (setjmp(jmploc.loc)) {
 452                 int e;
 453
 454                 handler = savehandler;
 455                 e = exception;
 456                 popredir();
 457                 if (e == EXERROR || e == EXEXEC) {
 458                         if (in_redirect) {
 459                                 exitstatus = 2;
 460                                 return;
 461                         }
 462                 }
 463                 longjmp(handler->loc, 1);
 464         } else {
 465                 INTOFF;
 466                 handler = &jmploc;
 467                 redirect(n->nredir.redirect, REDIR_PUSH);
 468                 in_redirect = 0;
 469                 INTON;
 470                 evaltree(n->nredir.n, flags);
 471         }
 472         INTOFF;
 473         handler = savehandler;
 474         popredir();
 475         INTON;
 476 }
 477
 478
 479 /*
 480  * Compute the names of the files in a redirection list.
 481  */
 482
 483 static void
 484 expredir(union node *n)
 485 {
 486         union node *redir;
 487
 488         for (redir = n ; redir ; redir = redir->nfile.next) {
 489                 struct arglist fn;
 490                 fn.lastp = &fn.list;
 491                 switch (redir->type) {
 492                 case NFROM:
 493                 case NTO:
 494                 case NFROMTO:
 495                 case NAPPEND:
 496                 case NCLOBBER:
 497                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 498                         redir->nfile.expfname = fn.list->text;
 499                         break;
 500                 case NFROMFD:
 501                 case NTOFD:
 502                         if (redir->ndup.vname) {
 503                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
 504                                 fixredir(redir, fn.list->text, 1);
 505                         }
 506                         break;
 507                 }
 508         }
 509 }
 510
 511
 512
 513 /*
 514  * Evaluate a pipeline.  All the processes in the pipeline are children
 515  * of the process creating the pipeline.  (This differs from some versions
 516  * of the shell, which make the last process in a pipeline the parent
 517  * of all the rest.)
 518  */
 519
 520 static void
 521 evalpipe(union node *n)
 522 {
 523         struct job *jp;
 524         struct nodelist *lp;
 525         int pipelen;
 526         int prevfd;
 527         int pip[2];
 528
 529         TRACE(("evalpipe(%p) called\n", (void *)n));
 530         pipelen = 0;
 531         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
 532                 pipelen++;
 533         INTOFF;
 534         jp = makejob(n, pipelen);
 535         prevfd = -1;
 536         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
 537                 prehash(lp->n);
 538                 pip[1] = -1;
 539                 if (lp->next) {
 540                         if (pipe(pip) < 0) {
 541                                 close(prevfd);
 542                                 error("Pipe call failed: %s", strerror(errno));
 543                         }
 544                 }
 545                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
 546                         INTON;
 547                         if (prevfd > 0) {
 548                                 dup2(prevfd, 0);
 549                                 close(prevfd);
 550                         }
 551                         if (pip[1] >= 0) {
 552                                 if (!(prevfd >= 0 && pip[0] == 0))
 553                                         close(pip[0]);
 554                                 if (pip[1] != 1) {
 555                                         dup2(pip[1], 1);
 556                                         close(pip[1]);
 557                                 }
 558                         }
 559                         evaltree(lp->n, EV_EXIT);
 560                 }
 561                 if (prevfd >= 0)
 562                         close(prevfd);
 563                 prevfd = pip[0];
 564                 if (pip[1] != -1)
 565                         close(pip[1]);
 566         }
 567         INTON;
 568         if (n->npipe.backgnd == 0) {
 569                 INTOFF;
 570                 exitstatus = waitforjob(jp, (int *)NULL);
 571                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 572                 INTON;
 573         } else
 574                 exitstatus = 0;
 575 }
 576
 577
 578
 579 static int
 580 is_valid_fast_cmdsubst(union node *n)
 581 {
 582
 583         return (n->type == NCMD);
 584 }
 585
 586 /*
 587  * Execute a command inside back quotes.  If it's a builtin command, we
 588  * want to save its output in a block obtained from malloc.  Otherwise
 589  * we fork off a subprocess and get the output of the command via a pipe.
 590  * Should be called with interrupts off.
 591  */
 592
 593 void
 594 evalbackcmd(union node *n, struct backcmd *result)
 595 {
 596         int pip[2];
 597         struct job *jp;
 598         struct stackmark smark;         /* unnecessary */
 599         struct jmploc jmploc;
 600         struct jmploc *savehandler;
 601         struct localvar *savelocalvars;
 602
 603         setstackmark(&smark);
 604         result->fd = -1;
 605         result->buf = NULL;
 606         result->nleft = 0;
 607         result->jp = NULL;
 608         if (n == NULL) {
 609                 exitstatus = 0;
 610                 goto out;
 611         }
 612         if (is_valid_fast_cmdsubst(n)) {
 613                 exitstatus = oexitstatus;
 614                 savelocalvars = localvars;
 615                 localvars = NULL;
 616                 forcelocal++;
 617                 savehandler = handler;
 618                 if (setjmp(jmploc.loc)) {
 619                         if (exception == EXERROR || exception == EXEXEC)
 620                                 exitstatus = 2;
 621                         else if (exception != 0) {
 622                                 handler = savehandler;
 623                                 forcelocal--;
 624                                 poplocalvars();
 625                                 localvars = savelocalvars;
 626                                 longjmp(handler->loc, 1);
 627                         }
 628                 } else {
 629                         handler = &jmploc;
 630                         evalcommand(n, EV_BACKCMD, result);
 631                 }
 632                 handler = savehandler;
 633                 forcelocal--;
 634                 poplocalvars();
 635                 localvars = savelocalvars;
 636         } else {
 637                 exitstatus = 0;
 638                 if (pipe(pip) < 0)
 639                         error("Pipe call failed: %s", strerror(errno));
 640                 jp = makejob(n, 1);
 641                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 642                         FORCEINTON;
 643                         close(pip[0]);
 644                         if (pip[1] != 1) {
 645                                 dup2(pip[1], 1);
 646                                 close(pip[1]);
 647                         }
 648                         evaltree(n, EV_EXIT);
 649                 }
 650                 close(pip[1]);
 651                 result->fd = pip[0];
 652                 result->jp = jp;
 653         }
 654 out:
 655         popstackmark(&smark);
 656         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 657                 result->fd, result->buf, result->nleft, result->jp));
 658 }
 659
 660 static int
 661 mustexpandto(const char *argtext, const char *mask)
 662 {
 663         for (;;) {
 664                 if (*argtext == CTLQUOTEMARK || *argtext == CTLQUOTEEND) {
 665                         argtext++;
 666                         continue;
 667                 }
 668                 if (*argtext == CTLESC)
 669                         argtext++;
 670                 else if (BASESYNTAX[(int)*argtext] == CCTL)
 671                         return (0);
 672                 if (*argtext != *mask)
 673                         return (0);
 674                 if (*argtext == '\0')
 675                         return (1);
 676                 argtext++;
 677                 mask++;
 678         }
 679 }
 680
 681 static int
 682 isdeclarationcmd(struct narg *arg)
 683 {
 684         int have_command = 0;
 685
 686         if (arg == NULL)
 687                 return (0);
 688         while (mustexpandto(arg->text, "command")) {
 689                 have_command = 1;
 690                 arg = &arg->next->narg;
 691                 if (arg == NULL)
 692                         return (0);
 693                 /*
 694                  * To also allow "command -p" and "command --" as part of
 695                  * a declaration command, add code here.
 696                  * We do not do this, as ksh does not do it either and it
 697                  * is not required by POSIX.
 698                  */
 699         }
 700         return (mustexpandto(arg->text, "export") ||
 701             mustexpandto(arg->text, "readonly") ||
 702             (mustexpandto(arg->text, "local") &&
 703                 (have_command || !isfunc("local"))));
 704 }
 705
 706 /*
 707  * Check if a builtin can safely be executed in the same process,
 708  * even though it should be in a subshell (command substitution).
 709  * Note that jobid, jobs, times and trap can show information not
 710  * available in a child process; this is deliberate.
 711  * The arguments should already have been expanded.
 712  */
 713 static int
 714 safe_builtin(int idx, int argc, char **argv)
 715 {
 716         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
 717             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
 718             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
 719             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
 720             idx == TYPECMD)
 721                 return (1);
 722         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 723             idx == UMASKCMD)
 724                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 725         if (idx == SETCMD)
 726                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 727                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 728                     argv[1][2] == '\0'));
 729         return (0);
 730 }
 731
 732 /*
 733  * Execute a simple command.
 734  * Note: This may or may not return if (flags & EV_EXIT).
 735  */
 736
 737 static void
 738 evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
 739 {
 740         struct stackmark smark;
 741         union node *argp;
 742         struct arglist arglist;
 743         struct arglist varlist;
 744         char **argv;
 745         int argc;
 746         char **envp;
 747         int varflag;
 748         struct strlist *sp;
 749         int mode;
 750         int pip[2];
 751         struct cmdentry cmdentry;
 752         struct job *jp;
 753         struct jmploc jmploc;
 754         struct jmploc *savehandler;
 755         char *savecmdname;
 756         struct shparam saveparam;
 757         struct localvar *savelocalvars;
 758         struct parsefile *savetopfile;
 759         volatile int e;
 760         char *lastarg;
 761         int realstatus;
 762         int do_clearcmdentry;
 763         const char *path = pathval();
 764
 765         /* First expand the arguments. */
 766         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 767         setstackmark(&smark);
 768         arglist.lastp = &arglist.list;
 769         varlist.lastp = &varlist.list;
 770         varflag = 1;
 771         jp = NULL;
 772         do_clearcmdentry = 0;
 773         oexitstatus = exitstatus;
 774         exitstatus = 0;
 775         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 776                 if (varflag && isassignment(argp->narg.text)) {
 777                         expandarg(argp, varflag == 1 ? &varlist : &arglist,
 778                             EXP_VARTILDE);
 779                         continue;
 780                 } else if (varflag == 1)
 781                         varflag = isdeclarationcmd(&argp->narg) ? 2 : 0;
 782                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 783         }
 784         *arglist.lastp = NULL;
 785         *varlist.lastp = NULL;
 786         expredir(cmd->ncmd.redirect);
 787         argc = 0;
 788         for (sp = arglist.list ; sp ; sp = sp->next)
 789                 argc++;
 790         /* Add one slot at the beginning for tryexec(). */
 791         argv = stalloc(sizeof (char *) * (argc + 2));
 792         argv++;
 793
 794         for (sp = arglist.list ; sp ; sp = sp->next) {
 795                 TRACE(("evalcommand arg: %s\n", sp->text));
 796                 *argv++ = sp->text;
 797         }
 798         *argv = NULL;
 799         lastarg = NULL;
 800         if (iflag && funcnest == 0 && argc > 0)
 801                 lastarg = argv[-1];
 802         argv -= argc;
 803
 804         /* Print the command if xflag is set. */
 805         if (xflag) {
 806                 char sep = 0;
 807                 const char *p, *ps4;
 808                 ps4 = expandstr(ps4val());
 809                 out2str(ps4 != NULL ? ps4 : ps4val());
 810                 for (sp = varlist.list ; sp ; sp = sp->next) {
 811                         if (sep != 0)
 812                                 out2c(' ');
 813                         p = strchr(sp->text, '=');
 814                         if (p != NULL) {
 815                                 p++;
 816                                 outbin(sp->text, p - sp->text, out2);
 817                                 out2qstr(p);
 818                         } else
 819                                 out2qstr(sp->text);
 820                         sep = ' ';
 821                 }
 822                 for (sp = arglist.list ; sp ; sp = sp->next) {
 823                         if (sep != 0)
 824                                 out2c(' ');
 825                         /* Disambiguate command looking like assignment. */
 826                         if (sp == arglist.list &&
 827                                         strchr(sp->text, '=') != NULL &&
 828                                         strchr(sp->text, '\'') == NULL) {
 829                                 out2c('\'');
 830                                 out2str(sp->text);
 831                                 out2c('\'');
 832                         } else
 833                                 out2qstr(sp->text);
 834                         sep = ' ';
 835                 }
 836                 out2c('\n');
 837                 flushout(&errout);
 838         }
 839
 840         /* Now locate the command. */
 841         if (argc == 0) {
 842                 /* Variable assignment(s) without command */
 843                 cmdentry.cmdtype = CMDBUILTIN;
 844                 cmdentry.u.index = BLTINCMD;
 845                 cmdentry.special = 0;
 846         } else {
 847                 static const char PATH[] = "PATH=";
 848                 int cmd_flags = 0, bltinonly = 0;
 849
 850                 /*
 851                  * Modify the command lookup path, if a PATH= assignment
 852                  * is present
 853                  */
 854                 for (sp = varlist.list ; sp ; sp = sp->next)
 855                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 856                                 path = sp->text + sizeof(PATH) - 1;
 857                                 /*
 858                                  * On `PATH=... command`, we need to make
 859                                  * sure that the command isn't using the
 860                                  * non-updated hash table of the outer PATH
 861                                  * setting and we need to make sure that
 862                                  * the hash table isn't filled with items
 863                                  * from the temporary setting.
 864                                  *
 865                                  * It would be better to forbit using and
 866                                  * updating the table while this command
 867                                  * runs, by the command finding mechanism
 868                                  * is heavily integrated with hash handling,
 869                                  * so we just delete the hash before and after
 870                                  * the command runs. Partly deleting like
 871                                  * changepatch() does doesn't seem worth the
 872                                  * bookinging effort, since most such runs add
 873                                  * directories in front of the new PATH.
 874                                  */
 875                                 clearcmdentry();
 876                                 do_clearcmdentry = 1;
 877                         }
 878
 879                 for (;;) {
 880                         if (bltinonly) {
 881                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 882                                 if (cmdentry.u.index < 0) {
 883                                         cmdentry.u.index = BLTINCMD;
 884                                         argv--;
 885                                         argc++;
 886                                         break;
 887                                 }
 888                         } else
 889                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 890                         /* implement the bltin and command builtins here */
 891                         if (cmdentry.cmdtype != CMDBUILTIN)
 892                                 break;
 893                         if (cmdentry.u.index == BLTINCMD) {
 894                                 if (argc == 1)
 895                                         break;
 896                                 argv++;
 897                                 argc--;
 898                                 bltinonly = 1;
 899                         } else if (cmdentry.u.index == COMMANDCMD) {
 900                                 if (argc == 1)
 901                                         break;
 902                                 if (!strcmp(argv[1], "-p")) {
 903                                         if (argc == 2)
 904                                                 break;
 905                                         if (argv[2][0] == '-') {
 906                                                 if (strcmp(argv[2], "--"))
 907                                                         break;
 908                                                 if (argc == 3)
 909                                                         break;
 910                                                 argv += 3;
 911                                                 argc -= 3;
 912                                         } else {
 913                                                 argv += 2;
 914                                                 argc -= 2;
 915                                         }
 916                                         path = _PATH_STDPATH;
 917                                         clearcmdentry();
 918                                         do_clearcmdentry = 1;
 919                                 } else if (!strcmp(argv[1], "--")) {
 920                                         if (argc == 2)
 921                                                 break;
 922                                         argv += 2;
 923                                         argc -= 2;
 924                                 } else if (argv[1][0] == '-')
 925                                         break;
 926                                 else {
 927                                         argv++;
 928                                         argc--;
 929                                 }
 930                                 cmd_flags |= DO_NOFUNC;
 931                                 bltinonly = 0;
 932                         } else
 933                                 break;
 934                 }
 935                 /*
 936                  * Special builtins lose their special properties when
 937                  * called via 'command'.
 938                  */
 939                 if (cmd_flags & DO_NOFUNC)
 940                         cmdentry.special = 0;
 941         }
 942
 943         /* Fork off a child process if necessary. */
 944         if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 945             && ((flags & EV_EXIT) == 0 || have_traps()))
 946          || ((flags & EV_BACKCMD) != 0
 947             && (cmdentry.cmdtype != CMDBUILTIN ||
 948                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 949                 jp = makejob(cmd, 1);
 950                 mode = FORK_FG;
 951                 if (flags & EV_BACKCMD) {
 952                         mode = FORK_NOJOB;
 953                         if (pipe(pip) < 0)
 954                                 error("Pipe call failed: %s", strerror(errno));
 955                 }
 956                 if (cmdentry.cmdtype == CMDNORMAL &&
 957                     cmd->ncmd.redirect == NULL &&
 958                     varlist.list == NULL &&
 959                     (mode == FORK_FG || mode == FORK_NOJOB) &&
 960                     !disvforkset() && !iflag && !mflag) {
 961                         vforkexecshell(jp, argv, environment(), path,
 962                             cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL);
 963                         goto parent;
 964                 }
 965                 if (forkshell(jp, cmd, mode) != 0)
 966                         goto parent;    /* at end of routine */
 967                 if (flags & EV_BACKCMD) {
 968                         FORCEINTON;
 969                         close(pip[0]);
 970                         if (pip[1] != 1) {
 971                                 dup2(pip[1], 1);
 972                                 close(pip[1]);
 973                         }
 974                         flags &= ~EV_BACKCMD;
 975                 }
 976                 flags |= EV_EXIT;
 977         }
 978
 979         /* This is the child process if a fork occurred. */
 980         /* Execute the command. */
 981         if (cmdentry.cmdtype == CMDFUNCTION) {
 982 #ifdef DEBUG
 983                 trputs("Shell function:  ");  trargs(argv);
 984 #endif
 985                 saveparam = shellparam;
 986                 shellparam.malloc = 0;
 987                 shellparam.reset = 1;
 988                 shellparam.nparam = argc - 1;
 989                 shellparam.p = argv + 1;
 990                 shellparam.optnext = NULL;
 991                 INTOFF;
 992                 savelocalvars = localvars;
 993                 localvars = NULL;
 994                 reffunc(cmdentry.u.func);
 995                 savehandler = handler;
 996                 if (setjmp(jmploc.loc)) {
 997                         freeparam(&shellparam);
 998                         shellparam = saveparam;
 999                         popredir();
1000                         unreffunc(cmdentry.u.func);
1001                         poplocalvars();
1002                         localvars = savelocalvars;
1003                         funcnest--;
1004                         handler = savehandler;
1005                         longjmp(handler->loc, 1);
1006                 }
1007                 handler = &jmploc;
1008                 funcnest++;
1009                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
1010                 INTON;
1011                 for (sp = varlist.list ; sp ; sp = sp->next)
1012                         mklocal(sp->text);
1013                 exitstatus = oexitstatus;
1014                 evaltree(getfuncnode(cmdentry.u.func),
1015                     flags & (EV_TESTED | EV_EXIT));
1016                 INTOFF;
1017                 unreffunc(cmdentry.u.func);
1018                 poplocalvars();
1019                 localvars = savelocalvars;
1020                 freeparam(&shellparam);
1021                 shellparam = saveparam;
1022                 handler = savehandler;
1023                 funcnest--;
1024                 popredir();
1025                 INTON;
1026                 if (evalskip == SKIPFUNC) {
1027                         evalskip = 0;
1028                         skipcount = 0;
1029                 }
1030                 if (jp)
1031                         exitshell(exitstatus);
1032         } else if (cmdentry.cmdtype == CMDBUILTIN) {
1033 #ifdef DEBUG
1034                 trputs("builtin command:  ");  trargs(argv);
1035 #endif
1036                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
1037                 if (flags == EV_BACKCMD) {
1038                         memout.nleft = 0;
1039                         memout.nextc = memout.buf;
1040                         memout.bufsize = 64;
1041                         mode |= REDIR_BACKQ;
1042                 }
1043                 savecmdname = commandname;
1044                 savetopfile = getcurrentfile();
1045                 cmdenviron = varlist.list;
1046                 e = -1;
1047                 savehandler = handler;
1048                 if (setjmp(jmploc.loc)) {
1049                         e = exception;
1050                         if (e == EXINT)
1051                                 exitstatus = SIGINT+128;
1052                         else if (e != EXEXIT)
1053                                 exitstatus = 2;
1054                         goto cmddone;
1055                 }
1056                 handler = &jmploc;
1057                 redirect(cmd->ncmd.redirect, mode);
1058                 /*
1059                  * If there is no command word, redirection errors should
1060                  * not be fatal but assignment errors should.
1061                  */
1062                 if (argc == 0)
1063                         cmdentry.special = 1;
1064                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1065                 if (argc > 0)
1066                         bltinsetlocale();
1067                 commandname = argv[0];
1068                 argptr = argv + 1;
1069                 nextopt_optptr = NULL;          /* initialize nextopt */
1070                 builtin_flags = flags;
1071                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1072                 flushall();
1073 cmddone:
1074                 if (argc > 0)
1075                         bltinunsetlocale();
1076                 cmdenviron = NULL;
1077                 out1 = &output;
1078                 out2 = &errout;
1079                 freestdout();
1080                 handler = savehandler;
1081                 commandname = savecmdname;
1082                 if (jp)
1083                         exitshell(exitstatus);
1084                 if (flags == EV_BACKCMD) {
1085                         backcmd->buf = memout.buf;
1086                         backcmd->nleft = memout.nextc - memout.buf;
1087                         memout.buf = NULL;
1088                 }
1089                 if (cmdentry.u.index != EXECCMD)
1090                         popredir();
1091                 if (e != -1) {
1092                         if ((e != EXERROR && e != EXEXEC)
1093                             || cmdentry.special)
1094                                 exraise(e);
1095                         popfilesupto(savetopfile);
1096                         if (flags != EV_BACKCMD)
1097                                 FORCEINTON;
1098                 }
1099         } else {
1100 #ifdef DEBUG
1101                 trputs("normal command:  ");  trargs(argv);
1102 #endif
1103                 redirect(cmd->ncmd.redirect, 0);
1104                 for (sp = varlist.list ; sp ; sp = sp->next)
1105                         setvareq(sp->text, VEXPORT|VSTACK);
1106                 envp = environment();
1107                 shellexec(argv, envp, path, cmdentry.u.index);
1108                 /*NOTREACHED*/
1109         }
1110         goto out;
1111
1112 parent: /* parent process gets here (if we forked) */
1113         if (mode == FORK_FG) {  /* argument to fork */
1114                 INTOFF;
1115                 exitstatus = waitforjob(jp, &realstatus);
1116                 INTON;
1117                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1118                         evalskip = SKIPBREAK;
1119                         skipcount = loopnest;
1120                 }
1121         } else if (mode == FORK_NOJOB) {
1122                 backcmd->fd = pip[0];
1123                 close(pip[1]);
1124                 backcmd->jp = jp;
1125         }
1126
1127 out:
1128         if (lastarg)
1129                 setvar("_", lastarg, 0);
1130         if (do_clearcmdentry)
1131                 clearcmdentry();
1132         popstackmark(&smark);
1133 }
1134
1135
1136
1137 /*
1138  * Search for a command.  This is called before we fork so that the
1139  * location of the command will be available in the parent as well as
1140  * the child.  The check for "goodname" is an overly conservative
1141  * check that the name will not be subject to expansion.
1142  */
1143
1144 static void
1145 prehash(union node *n)
1146 {
1147         struct cmdentry entry;
1148
1149         if (n && n->type == NCMD && n->ncmd.args)
1150                 if (goodname(n->ncmd.args->narg.text))
1151                         find_command(n->ncmd.args->narg.text, &entry, 0,
1152                                      pathval());
1153 }
1154
1155
1156
1157 /*
1158  * Builtin commands.  Builtin commands whose functions are closely
1159  * tied to evaluation are implemented here.
1160  */
1161
1162 /*
1163  * No command given, a bltin command with no arguments, or a bltin command
1164  * with an invalid name.
1165  */
1166
1167 int
1168 bltincmd(int argc, char **argv)
1169 {
1170         if (argc > 1) {
1171                 out2fmt_flush("%s: not found\n", argv[1]);
1172                 return 127;
1173         }
1174         /*
1175          * Preserve exitstatus of a previous possible redirection
1176          * as POSIX mandates
1177          */
1178         return exitstatus;
1179 }
1180
1181
1182 /*
1183  * Handle break and continue commands.  Break, continue, and return are
1184  * all handled by setting the evalskip flag.  The evaluation routines
1185  * above all check this flag, and if it is set they start skipping
1186  * commands rather than executing them.  The variable skipcount is
1187  * the number of loops to break/continue, or the number of function
1188  * levels to return.  (The latter is always 1.)  It should probably
1189  * be an error to break out of more loops than exist, but it isn't
1190  * in the standard shell so we don't make it one here.
1191  */
1192
1193 int
1194 breakcmd(int argc, char **argv)
1195 {
1196         int n = argc > 1 ? number(argv[1]) : 1;
1197
1198         if (n > loopnest)
1199                 n = loopnest;
1200         if (n > 0) {
1201                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1202                 skipcount = n;
1203         }
1204         return 0;
1205 }
1206
1207 /*
1208  * The `command' command.
1209  */
1210 int
1211 commandcmd(int argc, char **argv)
1212 {
1213         const char *path;
1214         int ch;
1215         int cmd = -1;
1216
1217         path = bltinlookup("PATH", 1);
1218
1219         optind = optreset = 1;
1220         opterr = 0;
1221         while ((ch = getopt(argc, argv, "pvV")) != -1) {
1222                 switch (ch) {
1223                 case 'p':
1224                         path = _PATH_STDPATH;
1225                         break;
1226                 case 'v':
1227                         cmd = TYPECMD_SMALLV;
1228                         break;
1229                 case 'V':
1230                         cmd = TYPECMD_BIGV;
1231                         break;
1232                 case '?':
1233                 default:
1234                         error("unknown option: -%c", optopt);
1235                 }
1236         }
1237         argc -= optind;
1238         argv += optind;
1239
1240         if (cmd != -1) {
1241                 if (argc != 1)
1242                         error("wrong number of arguments");
1243                 return typecmd_impl(2, argv - 1, cmd, path);
1244         }
1245         if (argc != 0)
1246                 error("commandcmd bad call");
1247
1248         /*
1249          * Do nothing successfully if no command was specified;
1250          * ksh also does this.
1251          */
1252         return 0;
1253 }
1254
1255
1256 /*
1257  * The return command.
1258  */
1259
1260 int
1261 returncmd(int argc, char **argv)
1262 {
1263         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1264
1265         if (funcnest) {
1266                 evalskip = SKIPFUNC;
1267                 skipcount = 1;
1268         } else {
1269                 /* skip the rest of the file */
1270                 evalskip = SKIPFILE;
1271                 skipcount = 1;
1272         }
1273         return ret;
1274 }
1275
1276
1277 int
1278 falsecmd(int argc __unused, char **argv __unused)
1279 {
1280         return 1;
1281 }
1282
1283
1284 int
1285 truecmd(int argc __unused, char **argv __unused)
1286 {
1287         return 0;
1288 }
1289
1290
1291 int
1292 execcmd(int argc, char **argv)
1293 {
1294         /*
1295          * Because we have historically not supported any options,
1296          * only treat "--" specially.
1297          */
1298         if (argc > 1 && strcmp(argv[1], "--") == 0)
1299                 argc--, argv++;
1300         if (argc > 1) {
1301                 struct strlist *sp;
1302
1303                 iflag = 0;              /* exit on error */
1304                 mflag = 0;
1305                 optschanged();
1306                 for (sp = cmdenviron; sp ; sp = sp->next)
1307                         setvareq(sp->text, VEXPORT|VSTACK);
1308                 shellexec(argv + 1, environment(), pathval(), 0);
1309
1310         }
1311         return 0;
1312 }
1313
1314
1315 int
1316 timescmd(int argc __unused, char **argv __unused)
1317 {
1318         struct rusage ru;
1319         long shumins, shsmins, chumins, chsmins;
1320         double shusecs, shssecs, chusecs, chssecs;
1321
1322         if (getrusage(RUSAGE_SELF, &ru) < 0)
1323                 return 1;
1324         shumins = ru.ru_utime.tv_sec / 60;
1325         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1326         shsmins = ru.ru_stime.tv_sec / 60;
1327         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1328         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1329                 return 1;
1330         chumins = ru.ru_utime.tv_sec / 60;
1331         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1332         chsmins = ru.ru_stime.tv_sec / 60;
1333         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1334         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1335             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1336         return 0;
1337 }