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 static 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 union node *evalcase(union node *);
  93 static void evalsubshell(union node *, int);
  94 static void evalredir(union node *, int);
  95 static void exphere(union node *, struct arglist *);
  96 static void expredir(union node *);
  97 static void evalpipe(union node *);
  98 static int is_valid_fast_cmdsubst(union node *n);
  99 static void evalcommand(union node *, int, struct backcmd *);
 100 static void prehash(union node *);
 101
 102
 103 /*
 104  * Called to reset things after an exception.
 105  */
 106
 107 void
 108 reseteval(void)
 109 {
 110         evalskip = 0;
 111         loopnest = 0;
 112         funcnest = 0;
 113 }
 114
 115
 116 /*
 117  * The eval command.
 118  */
 119
 120 int
 121 evalcmd(int argc, char **argv)
 122 {
 123         char *p;
 124         char *concat;
 125         char **ap;
 126
 127         if (argc > 1) {
 128                 p = argv[1];
 129                 if (argc > 2) {
 130                         STARTSTACKSTR(concat);
 131                         ap = argv + 2;
 132                         for (;;) {
 133                                 STPUTS(p, concat);
 134                                 if ((p = *ap++) == NULL)
 135                                         break;
 136                                 STPUTC(' ', concat);
 137                         }
 138                         STPUTC('\0', concat);
 139                         p = grabstackstr(concat);
 140                 }
 141                 evalstring(p, builtin_flags);
 142         } else
 143                 exitstatus = 0;
 144         return exitstatus;
 145 }
 146
 147
 148 /*
 149  * Execute a command or commands contained in a string.
 150  */
 151
 152 void
 153 evalstring(char *s, int flags)
 154 {
 155         union node *n;
 156         struct stackmark smark;
 157         int flags_exit;
 158         int any;
 159
 160         flags_exit = flags & EV_EXIT;
 161         flags &= ~EV_EXIT;
 162         any = 0;
 163         setstackmark(&smark);
 164         setinputstring(s, 1);
 165         while ((n = parsecmd(0)) != NEOF) {
 166                 if (n != NULL && !nflag) {
 167                         if (flags_exit && preadateof())
 168                                 evaltree(n, flags | EV_EXIT);
 169                         else
 170                                 evaltree(n, flags);
 171                         any = 1;
 172                 }
 173                 popstackmark(&smark);
 174                 setstackmark(&smark);
 175         }
 176         popfile();
 177         popstackmark(&smark);
 178         if (!any)
 179                 exitstatus = 0;
 180         if (flags_exit)
 181                 exraise(EXEXIT);
 182 }
 183
 184
 185 /*
 186  * Evaluate a parse tree.  The value is left in the global variable
 187  * exitstatus.
 188  */
 189
 190 void
 191 evaltree(union node *n, int flags)
 192 {
 193         int do_etest;
 194         union node *next;
 195         struct stackmark smark;
 196
 197         setstackmark(&smark);
 198         do_etest = 0;
 199         if (n == NULL) {
 200                 TRACE(("evaltree(NULL) called\n"));
 201                 exitstatus = 0;
 202                 goto out;
 203         }
 204         do {
 205                 next = NULL;
 206 #ifndef NO_HISTORY
 207                 displayhist = 1;        /* show history substitutions done with fc */
 208 #endif
 209                 TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
 210                 switch (n->type) {
 211                 case NSEMI:
 212                         evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
 213                         if (evalskip)
 214                                 goto out;
 215                         next = n->nbinary.ch2;
 216                         break;
 217                 case NAND:
 218                         evaltree(n->nbinary.ch1, EV_TESTED);
 219                         if (evalskip || exitstatus != 0) {
 220                                 goto out;
 221                         }
 222                         next = n->nbinary.ch2;
 223                         break;
 224                 case NOR:
 225                         evaltree(n->nbinary.ch1, EV_TESTED);
 226                         if (evalskip || exitstatus == 0)
 227                                 goto out;
 228                         next = n->nbinary.ch2;
 229                         break;
 230                 case NREDIR:
 231                         evalredir(n, flags);
 232                         break;
 233                 case NSUBSHELL:
 234                         evalsubshell(n, flags);
 235                         do_etest = !(flags & EV_TESTED);
 236                         break;
 237                 case NBACKGND:
 238                         evalsubshell(n, flags);
 239                         break;
 240                 case NIF: {
 241                         evaltree(n->nif.test, EV_TESTED);
 242                         if (evalskip)
 243                                 goto out;
 244                         if (exitstatus == 0)
 245                                 next = n->nif.ifpart;
 246                         else if (n->nif.elsepart)
 247                                 next = n->nif.elsepart;
 248                         else
 249                                 exitstatus = 0;
 250                         break;
 251                 }
 252                 case NWHILE:
 253                 case NUNTIL:
 254                         evalloop(n, flags & ~EV_EXIT);
 255                         break;
 256                 case NFOR:
 257                         evalfor(n, flags & ~EV_EXIT);
 258                         break;
 259                 case NCASE:
 260                         next = evalcase(n);
 261                         break;
 262                 case NCLIST:
 263                         next = n->nclist.body;
 264                         break;
 265                 case NCLISTFALLTHRU:
 266                         if (n->nclist.body) {
 267                                 evaltree(n->nclist.body, flags & ~EV_EXIT);
 268                                 if (evalskip)
 269                                         goto out;
 270                         }
 271                         next = n->nclist.next;
 272                         break;
 273                 case NDEFUN:
 274                         defun(n->narg.text, n->narg.next);
 275                         exitstatus = 0;
 276                         break;
 277                 case NNOT:
 278                         evaltree(n->nnot.com, EV_TESTED);
 279                         if (evalskip)
 280                                 goto out;
 281                         exitstatus = !exitstatus;
 282                         break;
 283
 284                 case NPIPE:
 285                         evalpipe(n);
 286                         do_etest = !(flags & EV_TESTED);
 287                         break;
 288                 case NCMD:
 289                         evalcommand(n, flags, (struct backcmd *)NULL);
 290                         do_etest = !(flags & EV_TESTED);
 291                         break;
 292                 default:
 293                         out1fmt("Node type = %d\n", n->type);
 294                         flushout(&output);
 295                         break;
 296                 }
 297                 n = next;
 298                 popstackmark(&smark);
 299                 setstackmark(&smark);
 300         } while (n != NULL);
 301 out:
 302         popstackmark(&smark);
 303         if (pendingsig)
 304                 dotrap();
 305         if (eflag && exitstatus != 0 && do_etest)
 306                 exitshell(exitstatus);
 307         if (flags & EV_EXIT)
 308                 exraise(EXEXIT);
 309 }
 310
 311
 312 static void
 313 evalloop(union node *n, int flags)
 314 {
 315         int status;
 316
 317         loopnest++;
 318         status = 0;
 319         for (;;) {
 320                 evaltree(n->nbinary.ch1, EV_TESTED);
 321                 if (evalskip) {
 322 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
 323                                 evalskip = 0;
 324                                 continue;
 325                         }
 326                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 327                                 evalskip = 0;
 328                         if (evalskip == SKIPFUNC || evalskip == SKIPFILE)
 329                                 status = exitstatus;
 330                         break;
 331                 }
 332                 if (n->type == NWHILE) {
 333                         if (exitstatus != 0)
 334                                 break;
 335                 } else {
 336                         if (exitstatus == 0)
 337                                 break;
 338                 }
 339                 evaltree(n->nbinary.ch2, flags);
 340                 status = exitstatus;
 341                 if (evalskip)
 342                         goto skipping;
 343         }
 344         loopnest--;
 345         exitstatus = status;
 346 }
 347
 348
 349
 350 static void
 351 evalfor(union node *n, int flags)
 352 {
 353         struct arglist arglist;
 354         union node *argp;
 355         struct strlist *sp;
 356         int status;
 357
 358         arglist.lastp = &arglist.list;
 359         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 360                 oexitstatus = exitstatus;
 361                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 362         }
 363         *arglist.lastp = NULL;
 364
 365         loopnest++;
 366         status = 0;
 367         for (sp = arglist.list ; sp ; sp = sp->next) {
 368                 setvar(n->nfor.var, sp->text, 0);
 369                 evaltree(n->nfor.body, flags);
 370                 status = exitstatus;
 371                 if (evalskip) {
 372                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 373                                 evalskip = 0;
 374                                 continue;
 375                         }
 376                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 377                                 evalskip = 0;
 378                         break;
 379                 }
 380         }
 381         loopnest--;
 382         exitstatus = status;
 383 }
 384
 385
 386 /*
 387  * Evaluate a case statement, returning the selected tree.
 388  *
 389  * The exit status needs care to get right.
 390  */
 391
 392 static union node *
 393 evalcase(union node *n)
 394 {
 395         union node *cp;
 396         union node *patp;
 397         struct arglist arglist;
 398
 399         arglist.lastp = &arglist.list;
 400         oexitstatus = exitstatus;
 401         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 402         for (cp = n->ncase.cases ; cp ; cp = cp->nclist.next) {
 403                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 404                         if (casematch(patp, arglist.list->text)) {
 405                                 while (cp->nclist.next &&
 406                                     cp->type == NCLISTFALLTHRU &&
 407                                     cp->nclist.body == NULL)
 408                                         cp = cp->nclist.next;
 409                                 if (cp->nclist.next &&
 410                                     cp->type == NCLISTFALLTHRU)
 411                                         return (cp);
 412                                 if (cp->nclist.body == NULL)
 413                                         exitstatus = 0;
 414                                 return (cp->nclist.body);
 415                         }
 416                 }
 417         }
 418         exitstatus = 0;
 419         return (NULL);
 420 }
 421
 422
 423
 424 /*
 425  * Kick off a subshell to evaluate a tree.
 426  */
 427
 428 static void
 429 evalsubshell(union node *n, int flags)
 430 {
 431         struct job *jp;
 432         int backgnd = (n->type == NBACKGND);
 433
 434         oexitstatus = exitstatus;
 435         expredir(n->nredir.redirect);
 436         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
 437                         forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
 438                 if (backgnd)
 439                         flags &=~ EV_TESTED;
 440                 redirect(n->nredir.redirect, 0);
 441                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 442         } else if (! backgnd) {
 443                 INTOFF;
 444                 exitstatus = waitforjob(jp, (int *)NULL);
 445                 INTON;
 446         } else
 447                 exitstatus = 0;
 448 }
 449
 450
 451 /*
 452  * Evaluate a redirected compound command.
 453  */
 454
 455 static void
 456 evalredir(union node *n, int flags)
 457 {
 458         struct jmploc jmploc;
 459         struct jmploc *savehandler;
 460         volatile int in_redirect = 1;
 461
 462         oexitstatus = exitstatus;
 463         expredir(n->nredir.redirect);
 464         savehandler = handler;
 465         if (setjmp(jmploc.loc)) {
 466                 int e;
 467
 468                 handler = savehandler;
 469                 e = exception;
 470                 popredir();
 471                 if (e == EXERROR || e == EXEXEC) {
 472                         if (in_redirect) {
 473                                 exitstatus = 2;
 474                                 return;
 475                         }
 476                 }
 477                 longjmp(handler->loc, 1);
 478         } else {
 479                 INTOFF;
 480                 handler = &jmploc;
 481                 redirect(n->nredir.redirect, REDIR_PUSH);
 482                 in_redirect = 0;
 483                 INTON;
 484                 evaltree(n->nredir.n, flags);
 485         }
 486         INTOFF;
 487         handler = savehandler;
 488         popredir();
 489         INTON;
 490 }
 491
 492
 493 static void
 494 exphere(union node *redir, struct arglist *fn)
 495 {
 496         struct jmploc jmploc;
 497         struct jmploc *savehandler;
 498         struct localvar *savelocalvars;
 499         int need_longjmp = 0;
 500
 501         redir->nhere.expdoc = nullstr;
 502         savelocalvars = localvars;
 503         localvars = NULL;
 504         forcelocal++;
 505         savehandler = handler;
 506         if (setjmp(jmploc.loc))
 507                 need_longjmp = exception != EXERROR && exception != EXEXEC;
 508         else {
 509                 handler = &jmploc;
 510                 expandarg(redir->nhere.doc, fn, 0);
 511                 redir->nhere.expdoc = fn->list->text;
 512                 INTOFF;
 513         }
 514         handler = savehandler;
 515         forcelocal--;
 516         poplocalvars();
 517         localvars = savelocalvars;
 518         if (need_longjmp)
 519                 longjmp(handler->loc, 1);
 520         INTON;
 521 }
 522
 523
 524 /*
 525  * Compute the names of the files in a redirection list.
 526  */
 527
 528 static void
 529 expredir(union node *n)
 530 {
 531         union node *redir;
 532
 533         for (redir = n ; redir ; redir = redir->nfile.next) {
 534                 struct arglist fn;
 535                 fn.lastp = &fn.list;
 536                 switch (redir->type) {
 537                 case NFROM:
 538                 case NTO:
 539                 case NFROMTO:
 540                 case NAPPEND:
 541                 case NCLOBBER:
 542                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 543                         redir->nfile.expfname = fn.list->text;
 544                         break;
 545                 case NFROMFD:
 546                 case NTOFD:
 547                         if (redir->ndup.vname) {
 548                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
 549                                 fixredir(redir, fn.list->text, 1);
 550                         }
 551                         break;
 552                 case NXHERE:
 553                         exphere(redir, &fn);
 554                         break;
 555                 }
 556         }
 557 }
 558
 559
 560
 561 /*
 562  * Evaluate a pipeline.  All the processes in the pipeline are children
 563  * of the process creating the pipeline.  (This differs from some versions
 564  * of the shell, which make the last process in a pipeline the parent
 565  * of all the rest.)
 566  */
 567
 568 static void
 569 evalpipe(union node *n)
 570 {
 571         struct job *jp;
 572         struct nodelist *lp;
 573         int pipelen;
 574         int prevfd;
 575         int pip[2];
 576
 577         TRACE(("evalpipe(%p) called\n", (void *)n));
 578         pipelen = 0;
 579         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
 580                 pipelen++;
 581         INTOFF;
 582         jp = makejob(n, pipelen);
 583         prevfd = -1;
 584         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
 585                 prehash(lp->n);
 586                 pip[1] = -1;
 587                 if (lp->next) {
 588                         if (pipe(pip) < 0) {
 589                                 if (prevfd >= 0)
 590                                         close(prevfd);
 591                                 error("Pipe call failed: %s", strerror(errno));
 592                         }
 593                 }
 594                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
 595                         INTON;
 596                         if (prevfd > 0) {
 597                                 dup2(prevfd, 0);
 598                                 close(prevfd);
 599                         }
 600                         if (pip[1] >= 0) {
 601                                 if (!(prevfd >= 0 && pip[0] == 0))
 602                                         close(pip[0]);
 603                                 if (pip[1] != 1) {
 604                                         dup2(pip[1], 1);
 605                                         close(pip[1]);
 606                                 }
 607                         }
 608                         evaltree(lp->n, EV_EXIT);
 609                 }
 610                 if (prevfd >= 0)
 611                         close(prevfd);
 612                 prevfd = pip[0];
 613                 if (pip[1] != -1)
 614                         close(pip[1]);
 615         }
 616         INTON;
 617         if (n->npipe.backgnd == 0) {
 618                 INTOFF;
 619                 exitstatus = waitforjob(jp, (int *)NULL);
 620                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 621                 INTON;
 622         } else
 623                 exitstatus = 0;
 624 }
 625
 626
 627
 628 static int
 629 is_valid_fast_cmdsubst(union node *n)
 630 {
 631
 632         return (n->type == NCMD);
 633 }
 634
 635 /*
 636  * Execute a command inside back quotes.  If it's a builtin command, we
 637  * want to save its output in a block obtained from malloc.  Otherwise
 638  * we fork off a subprocess and get the output of the command via a pipe.
 639  * Should be called with interrupts off.
 640  */
 641
 642 void
 643 evalbackcmd(union node *n, struct backcmd *result)
 644 {
 645         int pip[2];
 646         struct job *jp;
 647         struct stackmark smark;
 648         struct jmploc jmploc;
 649         struct jmploc *savehandler;
 650         struct localvar *savelocalvars;
 651
 652         setstackmark(&smark);
 653         result->fd = -1;
 654         result->buf = NULL;
 655         result->nleft = 0;
 656         result->jp = NULL;
 657         if (n == NULL) {
 658                 exitstatus = 0;
 659                 goto out;
 660         }
 661         exitstatus = oexitstatus;
 662         if (is_valid_fast_cmdsubst(n)) {
 663                 savelocalvars = localvars;
 664                 localvars = NULL;
 665                 forcelocal++;
 666                 savehandler = handler;
 667                 if (setjmp(jmploc.loc)) {
 668                         if (exception == EXERROR || exception == EXEXEC)
 669                                 exitstatus = 2;
 670                         else if (exception != 0) {
 671                                 handler = savehandler;
 672                                 forcelocal--;
 673                                 poplocalvars();
 674                                 localvars = savelocalvars;
 675                                 longjmp(handler->loc, 1);
 676                         }
 677                 } else {
 678                         handler = &jmploc;
 679                         evalcommand(n, EV_BACKCMD, result);
 680                 }
 681                 handler = savehandler;
 682                 forcelocal--;
 683                 poplocalvars();
 684                 localvars = savelocalvars;
 685         } else {
 686                 if (pipe(pip) < 0)
 687                         error("Pipe call failed: %s", strerror(errno));
 688                 jp = makejob(n, 1);
 689                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 690                         FORCEINTON;
 691                         close(pip[0]);
 692                         if (pip[1] != 1) {
 693                                 dup2(pip[1], 1);
 694                                 close(pip[1]);
 695                         }
 696                         evaltree(n, EV_EXIT);
 697                 }
 698                 close(pip[1]);
 699                 result->fd = pip[0];
 700                 result->jp = jp;
 701         }
 702 out:
 703         popstackmark(&smark);
 704         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 705                 result->fd, result->buf, result->nleft, result->jp));
 706 }
 707
 708 static int
 709 mustexpandto(const char *argtext, const char *mask)
 710 {
 711         for (;;) {
 712                 if (*argtext == CTLQUOTEMARK || *argtext == CTLQUOTEEND) {
 713                         argtext++;
 714                         continue;
 715                 }
 716                 if (*argtext == CTLESC)
 717                         argtext++;
 718                 else if (BASESYNTAX[(int)*argtext] == CCTL)
 719                         return (0);
 720                 if (*argtext != *mask)
 721                         return (0);
 722                 if (*argtext == '\0')
 723                         return (1);
 724                 argtext++;
 725                 mask++;
 726         }
 727 }
 728
 729 static int
 730 isdeclarationcmd(struct narg *arg)
 731 {
 732         int have_command = 0;
 733
 734         if (arg == NULL)
 735                 return (0);
 736         while (mustexpandto(arg->text, "command")) {
 737                 have_command = 1;
 738                 arg = &arg->next->narg;
 739                 if (arg == NULL)
 740                         return (0);
 741                 /*
 742                  * To also allow "command -p" and "command --" as part of
 743                  * a declaration command, add code here.
 744                  * We do not do this, as ksh does not do it either and it
 745                  * is not required by POSIX.
 746                  */
 747         }
 748         return (mustexpandto(arg->text, "export") ||
 749             mustexpandto(arg->text, "readonly") ||
 750             (mustexpandto(arg->text, "local") &&
 751                 (have_command || !isfunc("local"))));
 752 }
 753
 754 /*
 755  * Check if a builtin can safely be executed in the same process,
 756  * even though it should be in a subshell (command substitution).
 757  * Note that jobid, jobs, times and trap can show information not
 758  * available in a child process; this is deliberate.
 759  * The arguments should already have been expanded.
 760  */
 761 static int
 762 safe_builtin(int idx, int argc, char **argv)
 763 {
 764         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
 765             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
 766             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
 767             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
 768             idx == TYPECMD)
 769                 return (1);
 770         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 771             idx == UMASKCMD)
 772                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 773         if (idx == SETCMD)
 774                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 775                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 776                     argv[1][2] == '\0'));
 777         return (0);
 778 }
 779
 780 /*
 781  * Execute a simple command.
 782  * Note: This may or may not return if (flags & EV_EXIT).
 783  */
 784
 785 static void
 786 evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
 787 {
 788         union node *argp;
 789         struct arglist arglist;
 790         struct arglist varlist;
 791         char **argv;
 792         int argc;
 793         char **envp;
 794         int varflag;
 795         struct strlist *sp;
 796         int mode;
 797         int pip[2];
 798         struct cmdentry cmdentry;
 799         struct job *jp;
 800         struct jmploc jmploc;
 801         struct jmploc *savehandler;
 802         char *savecmdname;
 803         struct shparam saveparam;
 804         struct localvar *savelocalvars;
 805         struct parsefile *savetopfile;
 806         volatile int e;
 807         char *lastarg;
 808         int realstatus;
 809         int do_clearcmdentry;
 810         const char *path = pathval();
 811
 812         /* First expand the arguments. */
 813         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 814         arglist.lastp = &arglist.list;
 815         varlist.lastp = &varlist.list;
 816         varflag = 1;
 817         jp = NULL;
 818         do_clearcmdentry = 0;
 819         oexitstatus = exitstatus;
 820         exitstatus = 0;
 821         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 822                 if (varflag && isassignment(argp->narg.text)) {
 823                         expandarg(argp, varflag == 1 ? &varlist : &arglist,
 824                             EXP_VARTILDE);
 825                         continue;
 826                 } else if (varflag == 1)
 827                         varflag = isdeclarationcmd(&argp->narg) ? 2 : 0;
 828                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 829         }
 830         *arglist.lastp = NULL;
 831         *varlist.lastp = NULL;
 832         expredir(cmd->ncmd.redirect);
 833         argc = 0;
 834         for (sp = arglist.list ; sp ; sp = sp->next)
 835                 argc++;
 836         /* Add one slot at the beginning for tryexec(). */
 837         argv = stalloc(sizeof (char *) * (argc + 2));
 838         argv++;
 839
 840         for (sp = arglist.list ; sp ; sp = sp->next) {
 841                 TRACE(("evalcommand arg: %s\n", sp->text));
 842                 *argv++ = sp->text;
 843         }
 844         *argv = NULL;
 845         lastarg = NULL;
 846         if (iflag && funcnest == 0 && argc > 0)
 847                 lastarg = argv[-1];
 848         argv -= argc;
 849
 850         /* Print the command if xflag is set. */
 851         if (xflag) {
 852                 char sep = 0;
 853                 const char *p, *ps4;
 854                 ps4 = expandstr(ps4val());
 855                 out2str(ps4 != NULL ? ps4 : ps4val());
 856                 for (sp = varlist.list ; sp ; sp = sp->next) {
 857                         if (sep != 0)
 858                                 out2c(' ');
 859                         p = strchr(sp->text, '=');
 860                         if (p != NULL) {
 861                                 p++;
 862                                 outbin(sp->text, p - sp->text, out2);
 863                                 out2qstr(p);
 864                         } else
 865                                 out2qstr(sp->text);
 866                         sep = ' ';
 867                 }
 868                 for (sp = arglist.list ; sp ; sp = sp->next) {
 869                         if (sep != 0)
 870                                 out2c(' ');
 871                         /* Disambiguate command looking like assignment. */
 872                         if (sp == arglist.list &&
 873                                         strchr(sp->text, '=') != NULL &&
 874                                         strchr(sp->text, '\'') == NULL) {
 875                                 out2c('\'');
 876                                 out2str(sp->text);
 877                                 out2c('\'');
 878                         } else
 879                                 out2qstr(sp->text);
 880                         sep = ' ';
 881                 }
 882                 out2c('\n');
 883                 flushout(&errout);
 884         }
 885
 886         /* Now locate the command. */
 887         if (argc == 0) {
 888                 /* Variable assignment(s) without command */
 889                 cmdentry.cmdtype = CMDBUILTIN;
 890                 cmdentry.u.index = BLTINCMD;
 891                 cmdentry.special = 0;
 892         } else {
 893                 static const char PATH[] = "PATH=";
 894                 int cmd_flags = 0, bltinonly = 0;
 895
 896                 /*
 897                  * Modify the command lookup path, if a PATH= assignment
 898                  * is present
 899                  */
 900                 for (sp = varlist.list ; sp ; sp = sp->next)
 901                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 902                                 path = sp->text + sizeof(PATH) - 1;
 903                                 /*
 904                                  * On `PATH=... command`, we need to make
 905                                  * sure that the command isn't using the
 906                                  * non-updated hash table of the outer PATH
 907                                  * setting and we need to make sure that
 908                                  * the hash table isn't filled with items
 909                                  * from the temporary setting.
 910                                  *
 911                                  * It would be better to forbit using and
 912                                  * updating the table while this command
 913                                  * runs, by the command finding mechanism
 914                                  * is heavily integrated with hash handling,
 915                                  * so we just delete the hash before and after
 916                                  * the command runs. Partly deleting like
 917                                  * changepatch() does doesn't seem worth the
 918                                  * bookinging effort, since most such runs add
 919                                  * directories in front of the new PATH.
 920                                  */
 921                                 clearcmdentry();
 922                                 do_clearcmdentry = 1;
 923                         }
 924
 925                 for (;;) {
 926                         if (bltinonly) {
 927                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 928                                 if (cmdentry.u.index < 0) {
 929                                         cmdentry.u.index = BLTINCMD;
 930                                         argv--;
 931                                         argc++;
 932                                         break;
 933                                 }
 934                         } else
 935                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 936                         /* implement the bltin and command builtins here */
 937                         if (cmdentry.cmdtype != CMDBUILTIN)
 938                                 break;
 939                         if (cmdentry.u.index == BLTINCMD) {
 940                                 if (argc == 1)
 941                                         break;
 942                                 argv++;
 943                                 argc--;
 944                                 bltinonly = 1;
 945                         } else if (cmdentry.u.index == COMMANDCMD) {
 946                                 if (argc == 1)
 947                                         break;
 948                                 if (!strcmp(argv[1], "-p")) {
 949                                         if (argc == 2)
 950                                                 break;
 951                                         if (argv[2][0] == '-') {
 952                                                 if (strcmp(argv[2], "--"))
 953                                                         break;
 954                                                 if (argc == 3)
 955                                                         break;
 956                                                 argv += 3;
 957                                                 argc -= 3;
 958                                         } else {
 959                                                 argv += 2;
 960                                                 argc -= 2;
 961                                         }
 962                                         path = _PATH_STDPATH;
 963                                         clearcmdentry();
 964                                         do_clearcmdentry = 1;
 965                                 } else if (!strcmp(argv[1], "--")) {
 966                                         if (argc == 2)
 967                                                 break;
 968                                         argv += 2;
 969                                         argc -= 2;
 970                                 } else if (argv[1][0] == '-')
 971                                         break;
 972                                 else {
 973                                         argv++;
 974                                         argc--;
 975                                 }
 976                                 cmd_flags |= DO_NOFUNC;
 977                                 bltinonly = 0;
 978                         } else
 979                                 break;
 980                 }
 981                 /*
 982                  * Special builtins lose their special properties when
 983                  * called via 'command'.
 984                  */
 985                 if (cmd_flags & DO_NOFUNC)
 986                         cmdentry.special = 0;
 987         }
 988
 989         /* Fork off a child process if necessary. */
 990         if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 991             && ((flags & EV_EXIT) == 0 || have_traps()))
 992          || ((flags & EV_BACKCMD) != 0
 993             && (cmdentry.cmdtype != CMDBUILTIN ||
 994                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 995                 jp = makejob(cmd, 1);
 996                 mode = FORK_FG;
 997                 if (flags & EV_BACKCMD) {
 998                         mode = FORK_NOJOB;
 999                         if (pipe(pip) < 0)
1000                                 error("Pipe call failed: %s", strerror(errno));
1001                 }
1002                 if (cmdentry.cmdtype == CMDNORMAL &&
1003                     cmd->ncmd.redirect == NULL &&
1004                     varlist.list == NULL &&
1005                     (mode == FORK_FG || mode == FORK_NOJOB) &&
1006                     !disvforkset() && !iflag && !mflag) {
1007                         vforkexecshell(jp, argv, environment(), path,
1008                             cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL);
1009                         goto parent;
1010                 }
1011                 if (forkshell(jp, cmd, mode) != 0)
1012                         goto parent;    /* at end of routine */
1013                 if (flags & EV_BACKCMD) {
1014                         FORCEINTON;
1015                         close(pip[0]);
1016                         if (pip[1] != 1) {
1017                                 dup2(pip[1], 1);
1018                                 close(pip[1]);
1019                         }
1020                         flags &= ~EV_BACKCMD;
1021                 }
1022                 flags |= EV_EXIT;
1023         }
1024
1025         /* This is the child process if a fork occurred. */
1026         /* Execute the command. */
1027         if (cmdentry.cmdtype == CMDFUNCTION) {
1028 #ifdef DEBUG
1029                 trputs("Shell function:  ");  trargs(argv);
1030 #endif
1031                 saveparam = shellparam;
1032                 shellparam.malloc = 0;
1033                 shellparam.reset = 1;
1034                 shellparam.nparam = argc - 1;
1035                 shellparam.p = argv + 1;
1036                 shellparam.optnext = NULL;
1037                 INTOFF;
1038                 savelocalvars = localvars;
1039                 localvars = NULL;
1040                 reffunc(cmdentry.u.func);
1041                 savehandler = handler;
1042                 if (setjmp(jmploc.loc)) {
1043                         freeparam(&shellparam);
1044                         shellparam = saveparam;
1045                         popredir();
1046                         unreffunc(cmdentry.u.func);
1047                         poplocalvars();
1048                         localvars = savelocalvars;
1049                         funcnest--;
1050                         handler = savehandler;
1051                         longjmp(handler->loc, 1);
1052                 }
1053                 handler = &jmploc;
1054                 funcnest++;
1055                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
1056                 INTON;
1057                 for (sp = varlist.list ; sp ; sp = sp->next)
1058                         mklocal(sp->text);
1059                 exitstatus = oexitstatus;
1060                 evaltree(getfuncnode(cmdentry.u.func),
1061                     flags & (EV_TESTED | EV_EXIT));
1062                 INTOFF;
1063                 unreffunc(cmdentry.u.func);
1064                 poplocalvars();
1065                 localvars = savelocalvars;
1066                 freeparam(&shellparam);
1067                 shellparam = saveparam;
1068                 handler = savehandler;
1069                 funcnest--;
1070                 popredir();
1071                 INTON;
1072                 if (evalskip == SKIPFUNC) {
1073                         evalskip = 0;
1074                         skipcount = 0;
1075                 }
1076                 if (jp)
1077                         exitshell(exitstatus);
1078         } else if (cmdentry.cmdtype == CMDBUILTIN) {
1079 #ifdef DEBUG
1080                 trputs("builtin command:  ");  trargs(argv);
1081 #endif
1082                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
1083                 if (flags == EV_BACKCMD) {
1084                         memout.nleft = 0;
1085                         memout.nextc = memout.buf;
1086                         memout.bufsize = 64;
1087                         mode |= REDIR_BACKQ;
1088                 }
1089                 savecmdname = commandname;
1090                 savetopfile = getcurrentfile();
1091                 cmdenviron = varlist.list;
1092                 e = -1;
1093                 savehandler = handler;
1094                 if (setjmp(jmploc.loc)) {
1095                         e = exception;
1096                         if (e == EXINT)
1097                                 exitstatus = SIGINT+128;
1098                         else if (e != EXEXIT)
1099                                 exitstatus = 2;
1100                         goto cmddone;
1101                 }
1102                 handler = &jmploc;
1103                 redirect(cmd->ncmd.redirect, mode);
1104                 outclearerror(out1);
1105                 /*
1106                  * If there is no command word, redirection errors should
1107                  * not be fatal but assignment errors should.
1108                  */
1109                 if (argc == 0)
1110                         cmdentry.special = 1;
1111                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1112                 if (argc > 0)
1113                         bltinsetlocale();
1114                 commandname = argv[0];
1115                 argptr = argv + 1;
1116                 nextopt_optptr = NULL;          /* initialize nextopt */
1117                 builtin_flags = flags;
1118                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1119                 flushall();
1120                 if (outiserror(out1)) {
1121                         warning("write error on stdout");
1122                         if (exitstatus == 0 || exitstatus == 1)
1123                                 exitstatus = 2;
1124                 }
1125 cmddone:
1126                 if (argc > 0)
1127                         bltinunsetlocale();
1128                 cmdenviron = NULL;
1129                 out1 = &output;
1130                 out2 = &errout;
1131                 freestdout();
1132                 handler = savehandler;
1133                 commandname = savecmdname;
1134                 if (jp)
1135                         exitshell(exitstatus);
1136                 if (flags == EV_BACKCMD) {
1137                         backcmd->buf = memout.buf;
1138                         backcmd->nleft = memout.nextc - memout.buf;
1139                         memout.buf = NULL;
1140                 }
1141                 if (cmdentry.u.index != EXECCMD)
1142                         popredir();
1143                 if (e != -1) {
1144                         if ((e != EXERROR && e != EXEXEC)
1145                             || cmdentry.special)
1146                                 exraise(e);
1147                         popfilesupto(savetopfile);
1148                         if (flags != EV_BACKCMD)
1149                                 FORCEINTON;
1150                 }
1151         } else {
1152 #ifdef DEBUG
1153                 trputs("normal command:  ");  trargs(argv);
1154 #endif
1155                 redirect(cmd->ncmd.redirect, 0);
1156                 for (sp = varlist.list ; sp ; sp = sp->next)
1157                         setvareq(sp->text, VEXPORT|VSTACK);
1158                 envp = environment();
1159                 shellexec(argv, envp, path, cmdentry.u.index);
1160                 /*NOTREACHED*/
1161         }
1162         goto out;
1163
1164 parent: /* parent process gets here (if we forked) */
1165         if (mode == FORK_FG) {  /* argument to fork */
1166                 INTOFF;
1167                 exitstatus = waitforjob(jp, &realstatus);
1168                 INTON;
1169                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1170                         evalskip = SKIPBREAK;
1171                         skipcount = loopnest;
1172                 }
1173         } else if (mode == FORK_NOJOB) {
1174                 backcmd->fd = pip[0];
1175                 close(pip[1]);
1176                 backcmd->jp = jp;
1177         }
1178
1179 out:
1180         if (lastarg)
1181                 setvar("_", lastarg, 0);
1182         if (do_clearcmdentry)
1183                 clearcmdentry();
1184 }
1185
1186
1187
1188 /*
1189  * Search for a command.  This is called before we fork so that the
1190  * location of the command will be available in the parent as well as
1191  * the child.  The check for "goodname" is an overly conservative
1192  * check that the name will not be subject to expansion.
1193  */
1194
1195 static void
1196 prehash(union node *n)
1197 {
1198         struct cmdentry entry;
1199
1200         if (n && n->type == NCMD && n->ncmd.args)
1201                 if (goodname(n->ncmd.args->narg.text))
1202                         find_command(n->ncmd.args->narg.text, &entry, 0,
1203                                      pathval());
1204 }
1205
1206
1207
1208 /*
1209  * Builtin commands.  Builtin commands whose functions are closely
1210  * tied to evaluation are implemented here.
1211  */
1212
1213 /*
1214  * No command given, a bltin command with no arguments, or a bltin command
1215  * with an invalid name.
1216  */
1217
1218 int
1219 bltincmd(int argc, char **argv)
1220 {
1221         if (argc > 1) {
1222                 out2fmt_flush("%s: not found\n", argv[1]);
1223                 return 127;
1224         }
1225         /*
1226          * Preserve exitstatus of a previous possible redirection
1227          * as POSIX mandates
1228          */
1229         return exitstatus;
1230 }
1231
1232
1233 /*
1234  * Handle break and continue commands.  Break, continue, and return are
1235  * all handled by setting the evalskip flag.  The evaluation routines
1236  * above all check this flag, and if it is set they start skipping
1237  * commands rather than executing them.  The variable skipcount is
1238  * the number of loops to break/continue, or the number of function
1239  * levels to return.  (The latter is always 1.)  It should probably
1240  * be an error to break out of more loops than exist, but it isn't
1241  * in the standard shell so we don't make it one here.
1242  */
1243
1244 int
1245 breakcmd(int argc, char **argv)
1246 {
1247         int n = argc > 1 ? number(argv[1]) : 1;
1248
1249         if (n > loopnest)
1250                 n = loopnest;
1251         if (n > 0) {
1252                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1253                 skipcount = n;
1254         }
1255         return 0;
1256 }
1257
1258 /*
1259  * The `command' command.
1260  */
1261 int
1262 commandcmd(int argc __unused, char **argv __unused)
1263 {
1264         const char *path;
1265         int ch;
1266         int cmd = -1;
1267
1268         path = bltinlookup("PATH", 1);
1269
1270         while ((ch = nextopt("pvV")) != '\0') {
1271                 switch (ch) {
1272                 case 'p':
1273                         path = _PATH_STDPATH;
1274                         break;
1275                 case 'v':
1276                         cmd = TYPECMD_SMALLV;
1277                         break;
1278                 case 'V':
1279                         cmd = TYPECMD_BIGV;
1280                         break;
1281                 }
1282         }
1283
1284         if (cmd != -1) {
1285                 if (*argptr == NULL || argptr[1] != NULL)
1286                         error("wrong number of arguments");
1287                 return typecmd_impl(2, argptr - 1, cmd, path);
1288         }
1289         if (*argptr != NULL)
1290                 error("commandcmd bad call");
1291
1292         /*
1293          * Do nothing successfully if no command was specified;
1294          * ksh also does this.
1295          */
1296         return 0;
1297 }
1298
1299
1300 /*
1301  * The return command.
1302  */
1303
1304 int
1305 returncmd(int argc, char **argv)
1306 {
1307         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1308
1309         if (funcnest) {
1310                 evalskip = SKIPFUNC;
1311                 skipcount = 1;
1312         } else {
1313                 /* skip the rest of the file */
1314                 evalskip = SKIPFILE;
1315                 skipcount = 1;
1316         }
1317         return ret;
1318 }
1319
1320
1321 int
1322 falsecmd(int argc __unused, char **argv __unused)
1323 {
1324         return 1;
1325 }
1326
1327
1328 int
1329 truecmd(int argc __unused, char **argv __unused)
1330 {
1331         return 0;
1332 }
1333
1334
1335 int
1336 execcmd(int argc, char **argv)
1337 {
1338         /*
1339          * Because we have historically not supported any options,
1340          * only treat "--" specially.
1341          */
1342         if (argc > 1 && strcmp(argv[1], "--") == 0)
1343                 argc--, argv++;
1344         if (argc > 1) {
1345                 struct strlist *sp;
1346
1347                 iflag = 0;              /* exit on error */
1348                 mflag = 0;
1349                 optschanged();
1350                 for (sp = cmdenviron; sp ; sp = sp->next)
1351                         setvareq(sp->text, VEXPORT|VSTACK);
1352                 shellexec(argv + 1, environment(), pathval(), 0);
1353
1354         }
1355         return 0;
1356 }
1357
1358
1359 int
1360 timescmd(int argc __unused, char **argv __unused)
1361 {
1362         struct rusage ru;
1363         long shumins, shsmins, chumins, chsmins;
1364         double shusecs, shssecs, chusecs, chssecs;
1365
1366         if (getrusage(RUSAGE_SELF, &ru) < 0)
1367                 return 1;
1368         shumins = ru.ru_utime.tv_sec / 60;
1369         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1370         shsmins = ru.ru_stime.tv_sec / 60;
1371         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1372         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1373                 return 1;
1374         chumins = ru.ru_utime.tv_sec / 60;
1375         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1376         chsmins = ru.ru_stime.tv_sec / 60;
1377         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1378         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1379             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1380         return 0;
1381 }