bin/sh/eval.c

   1 /*-
   2  * Copyright (c) 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Kenneth Almquist.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * @(#)eval.c   8.9 (Berkeley) 6/8/95
  37  * $FreeBSD: head/bin/sh/eval.c 247206 2013-02-23 22:50:57Z jilles $
  38  */
  39
  40 #include <sys/time.h>
  41 #include <sys/resource.h>
  42 #include <sys/wait.h> /* For WIFSIGNALED(status) */
  43
  44 #include <errno.h>
  45 #include <paths.h>
  46 #include <signal.h>
  47 #include <stdlib.h>
  48 #include <unistd.h>
  49
  50 /*
  51  * Evaluate a command.
  52  */
  53
  54 #include "shell.h"
  55 #include "nodes.h"
  56 #include "syntax.h"
  57 #include "expand.h"
  58 #include "parser.h"
  59 #include "jobs.h"
  60 #include "eval.h"
  61 #include "builtins.h"
  62 #include "options.h"
  63 #include "exec.h"
  64 #include "redir.h"
  65 #include "input.h"
  66 #include "output.h"
  67 #include "trap.h"
  68 #include "var.h"
  69 #include "memalloc.h"
  70 #include "error.h"
  71 #include "show.h"
  72 #include "mystring.h"
  73 #ifndef NO_HISTORY
  74 #include "myhistedit.h"
  75 #endif
  76
  77
  78 int evalskip;                   /* set if we are skipping commands */
  79 int skipcount;                  /* number of levels to skip */
  80 MKINIT int loopnest;            /* current loop nesting level */
  81 int funcnest;                   /* depth of function calls */
  82 static int builtin_flags;       /* evalcommand flags for builtins */
  83
  84
  85 const char *commandname;
  86 struct strlist *cmdenviron;
  87 int exitstatus;                 /* exit status of last command */
  88 int oexitstatus;                /* saved exit status */
  89
  90
  91 static void evalloop(union node *, int);
  92 static void evalfor(union node *, int);
  93 static union node *evalcase(union node *);
  94 static void evalsubshell(union node *, int);
  95 static void evalredir(union node *, int);
  96 static void exphere(union node *, struct arglist *);
  97 static void expredir(union node *);
  98 static void evalpipe(union node *);
  99 static int is_valid_fast_cmdsubst(union node *n);
 100 static void evalcommand(union node *, int, struct backcmd *);
 101 static void prehash(union node *);
 102
 103
 104 /*
 105  * Called to reset things after an exception.
 106  */
 107
 108 #ifdef mkinit
 109 INCLUDE "eval.h"
 110
 111 RESET {
 112         evalskip = 0;
 113         loopnest = 0;
 114         funcnest = 0;
 115 }
 116 #endif
 117
 118
 119
 120 /*
 121  * The eval command.
 122  */
 123
 124 int
 125 evalcmd(int argc, char **argv)
 126 {
 127         char *p;
 128         char *concat;
 129         char **ap;
 130
 131         if (argc > 1) {
 132                 p = argv[1];
 133                 if (argc > 2) {
 134                         STARTSTACKSTR(concat);
 135                         ap = argv + 2;
 136                         for (;;) {
 137                                 STPUTS(p, concat);
 138                                 if ((p = *ap++) == NULL)
 139                                         break;
 140                                 STPUTC(' ', concat);
 141                         }
 142                         STPUTC('\0', concat);
 143                         p = grabstackstr(concat);
 144                 }
 145                 evalstring(p, builtin_flags);
 146         } else
 147                 exitstatus = 0;
 148         return exitstatus;
 149 }
 150
 151
 152 /*
 153  * Execute a command or commands contained in a string.
 154  */
 155
 156 void
 157 evalstring(char *s, int flags)
 158 {
 159         union node *n;
 160         struct stackmark smark;
 161         int flags_exit;
 162         int any;
 163
 164         flags_exit = flags & EV_EXIT;
 165         flags &= ~EV_EXIT;
 166         any = 0;
 167         setstackmark(&smark);
 168         setinputstring(s, 1);
 169         while ((n = parsecmd(0)) != NEOF) {
 170                 if (n != NULL && !nflag) {
 171                         if (flags_exit && preadateof())
 172                                 evaltree(n, flags | EV_EXIT);
 173                         else
 174                                 evaltree(n, flags);
 175                         any = 1;
 176                 }
 177                 popstackmark(&smark);
 178                 setstackmark(&smark);
 179         }
 180         popfile();
 181         popstackmark(&smark);
 182         if (!any)
 183                 exitstatus = 0;
 184         if (flags_exit)
 185                 exraise(EXEXIT);
 186 }
 187
 188
 189 /*
 190  * Evaluate a parse tree.  The value is left in the global variable
 191  * exitstatus.
 192  */
 193
 194 void
 195 evaltree(union node *n, int flags)
 196 {
 197         int do_etest;
 198         union node *next;
 199         struct stackmark smark;
 200
 201         setstackmark(&smark);
 202         do_etest = 0;
 203         if (n == NULL) {
 204                 TRACE(("evaltree(NULL) called\n"));
 205                 exitstatus = 0;
 206                 goto out;
 207         }
 208         do {
 209                 next = NULL;
 210 #ifndef NO_HISTORY
 211                 displayhist = 1;        /* show history substitutions done with fc */
 212 #endif
 213                 TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
 214                 switch (n->type) {
 215                 case NSEMI:
 216                         evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
 217                         if (evalskip)
 218                                 goto out;
 219                         next = n->nbinary.ch2;
 220                         break;
 221                 case NAND:
 222                         evaltree(n->nbinary.ch1, EV_TESTED);
 223                         if (evalskip || exitstatus != 0) {
 224                                 goto out;
 225                         }
 226                         next = n->nbinary.ch2;
 227                         break;
 228                 case NOR:
 229                         evaltree(n->nbinary.ch1, EV_TESTED);
 230                         if (evalskip || exitstatus == 0)
 231                                 goto out;
 232                         next = n->nbinary.ch2;
 233                         break;
 234                 case NREDIR:
 235                         evalredir(n, flags);
 236                         break;
 237                 case NSUBSHELL:
 238                         evalsubshell(n, flags);
 239                         do_etest = !(flags & EV_TESTED);
 240                         break;
 241                 case NBACKGND:
 242                         evalsubshell(n, flags);
 243                         break;
 244                 case NIF: {
 245                         evaltree(n->nif.test, EV_TESTED);
 246                         if (evalskip)
 247                                 goto out;
 248                         if (exitstatus == 0)
 249                                 next = n->nif.ifpart;
 250                         else if (n->nif.elsepart)
 251                                 next = n->nif.elsepart;
 252                         else
 253                                 exitstatus = 0;
 254                         break;
 255                 }
 256                 case NWHILE:
 257                 case NUNTIL:
 258                         evalloop(n, flags & ~EV_EXIT);
 259                         break;
 260                 case NFOR:
 261                         evalfor(n, flags & ~EV_EXIT);
 262                         break;
 263                 case NCASE:
 264                         next = evalcase(n);
 265                         break;
 266                 case NCLIST:
 267                         next = n->nclist.body;
 268                         break;
 269                 case NCLISTFALLTHRU:
 270                         if (n->nclist.body) {
 271                                 evaltree(n->nclist.body, flags & ~EV_EXIT);
 272                                 if (evalskip)
 273                                         goto out;
 274                         }
 275                         next = n->nclist.next;
 276                         break;
 277                 case NDEFUN:
 278                         defun(n->narg.text, n->narg.next);
 279                         exitstatus = 0;
 280                         break;
 281                 case NNOT:
 282                         evaltree(n->nnot.com, EV_TESTED);
 283                         exitstatus = !exitstatus;
 284                         break;
 285
 286                 case NPIPE:
 287                         evalpipe(n);
 288                         do_etest = !(flags & EV_TESTED);
 289                         break;
 290                 case NCMD:
 291                         evalcommand(n, flags, NULL);
 292                         do_etest = !(flags & EV_TESTED);
 293                         break;
 294                 default:
 295                         out1fmt("Node type = %d\n", n->type);
 296                         flushout(&output);
 297                         break;
 298                 }
 299                 n = next;
 300                 popstackmark(&smark);
 301                 setstackmark(&smark);
 302         } while (n != NULL);
 303 out:
 304         popstackmark(&smark);
 305         if (pendingsig)
 306                 dotrap();
 307         if (eflag && exitstatus != 0 && do_etest)
 308                 exitshell(exitstatus);
 309         if (flags & EV_EXIT)
 310                 exraise(EXEXIT);
 311 }
 312
 313
 314 static void
 315 evalloop(union node *n, int flags)
 316 {
 317         int status;
 318
 319         loopnest++;
 320         status = 0;
 321         for (;;) {
 322                 evaltree(n->nbinary.ch1, EV_TESTED);
 323                 if (evalskip) {
 324 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
 325                                 evalskip = 0;
 326                                 continue;
 327                         }
 328                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 329                                 evalskip = 0;
 330                         if (evalskip == SKIPFUNC || evalskip == SKIPFILE)
 331                                 status = exitstatus;
 332                         break;
 333                 }
 334                 if (n->type == NWHILE) {
 335                         if (exitstatus != 0)
 336                                 break;
 337                 } else {
 338                         if (exitstatus == 0)
 339                                 break;
 340                 }
 341                 evaltree(n->nbinary.ch2, flags);
 342                 status = exitstatus;
 343                 if (evalskip)
 344                         goto skipping;
 345         }
 346         loopnest--;
 347         exitstatus = status;
 348 }
 349
 350
 351
 352 static void
 353 evalfor(union node *n, int flags)
 354 {
 355         struct arglist arglist;
 356         union node *argp;
 357         struct strlist *sp;
 358         int status;
 359
 360         arglist.lastp = &arglist.list;
 361         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 362                 oexitstatus = exitstatus;
 363                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 364         }
 365         *arglist.lastp = NULL;
 366
 367         loopnest++;
 368         status = 0;
 369         for (sp = arglist.list ; sp ; sp = sp->next) {
 370                 setvar(n->nfor.var, sp->text, 0);
 371                 evaltree(n->nfor.body, flags);
 372                 status = exitstatus;
 373                 if (evalskip) {
 374                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 375                                 evalskip = 0;
 376                                 continue;
 377                         }
 378                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 379                                 evalskip = 0;
 380                         break;
 381                 }
 382         }
 383         loopnest--;
 384         exitstatus = status;
 385 }
 386
 387
 388 /*
 389  * Evaluate a case statement, returning the selected tree.
 390  *
 391  * The exit status needs care to get right.
 392  */
 393
 394 static union node *
 395 evalcase(union node *n)
 396 {
 397         union node *cp;
 398         union node *patp;
 399         struct arglist arglist;
 400
 401         arglist.lastp = &arglist.list;
 402         oexitstatus = exitstatus;
 403         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 404         for (cp = n->ncase.cases ; cp ; cp = cp->nclist.next) {
 405                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 406                         if (casematch(patp, arglist.list->text)) {
 407                                 while (cp->nclist.next &&
 408                                     cp->type == NCLISTFALLTHRU &&
 409                                     cp->nclist.body == NULL)
 410                                         cp = cp->nclist.next;
 411                                 if (cp->nclist.next &&
 412                                     cp->type == NCLISTFALLTHRU)
 413                                         return (cp);
 414                                 if (cp->nclist.body == NULL)
 415                                         exitstatus = 0;
 416                                 return (cp->nclist.body);
 417                         }
 418                 }
 419         }
 420         exitstatus = 0;
 421         return (NULL);
 422 }
 423
 424
 425
 426 /*
 427  * Kick off a subshell to evaluate a tree.
 428  */
 429
 430 static void
 431 evalsubshell(union node *n, int flags)
 432 {
 433         struct job *jp;
 434         int backgnd = (n->type == NBACKGND);
 435
 436         oexitstatus = exitstatus;
 437         expredir(n->nredir.redirect);
 438         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
 439             forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
 440                 if (backgnd)
 441                         flags &=~ EV_TESTED;
 442                 redirect(n->nredir.redirect, 0);
 443                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 444         } else if (!backgnd) {
 445                 INTOFF;
 446                 exitstatus = waitforjob(jp, NULL);
 447                 INTON;
 448         } else
 449                 exitstatus = 0;
 450 }
 451
 452
 453 /*
 454  * Evaluate a redirected compound command.
 455  */
 456
 457 static void
 458 evalredir(union node *n, int flags)
 459 {
 460         struct jmploc jmploc;
 461         struct jmploc *savehandler;
 462         volatile int in_redirect = 1;
 463
 464         oexitstatus = exitstatus;
 465         expredir(n->nredir.redirect);
 466         savehandler = handler;
 467         if (setjmp(jmploc.loc)) {
 468                 int e;
 469
 470                 handler = savehandler;
 471                 e = exception;
 472                 popredir();
 473                 if (e == EXERROR || e == EXEXEC) {
 474                         if (in_redirect) {
 475                                 exitstatus = 2;
 476                                 return;
 477                         }
 478                 }
 479                 longjmp(handler->loc, 1);
 480         } else {
 481                 INTOFF;
 482                 handler = &jmploc;
 483                 redirect(n->nredir.redirect, REDIR_PUSH);
 484                 in_redirect = 0;
 485                 INTON;
 486                 evaltree(n->nredir.n, flags);
 487         }
 488         INTOFF;
 489         handler = savehandler;
 490         popredir();
 491         INTON;
 492 }
 493
 494
 495 static void
 496 exphere(union node *redir, struct arglist *fn)
 497 {
 498         struct jmploc jmploc;
 499         struct jmploc *savehandler;
 500         struct localvar *savelocalvars;
 501         int need_longjmp = 0;
 502
 503         redir->nhere.expdoc = nullstr;
 504         savelocalvars = localvars;
 505         localvars = NULL;
 506         forcelocal++;
 507         savehandler = handler;
 508         if (setjmp(jmploc.loc))
 509                 need_longjmp = exception != EXERROR && exception != EXEXEC;
 510         else {
 511                 handler = &jmploc;
 512                 expandarg(redir->nhere.doc, fn, 0);
 513                 redir->nhere.expdoc = fn->list->text;
 514                 INTOFF;
 515         }
 516         handler = savehandler;
 517         forcelocal--;
 518         poplocalvars();
 519         localvars = savelocalvars;
 520         if (need_longjmp)
 521                 longjmp(handler->loc, 1);
 522         INTON;
 523 }
 524
 525
 526 /*
 527  * Compute the names of the files in a redirection list.
 528  */
 529
 530 static void
 531 expredir(union node *n)
 532 {
 533         union node *redir;
 534
 535         for (redir = n ; redir ; redir = redir->nfile.next) {
 536                 struct arglist fn;
 537                 fn.lastp = &fn.list;
 538                 switch (redir->type) {
 539                 case NFROM:
 540                 case NTO:
 541                 case NFROMTO:
 542                 case NAPPEND:
 543                 case NCLOBBER:
 544                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 545                         redir->nfile.expfname = fn.list->text;
 546                         break;
 547                 case NFROMFD:
 548                 case NTOFD:
 549                         if (redir->ndup.vname) {
 550                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
 551                                 fixredir(redir, fn.list->text, 1);
 552                         }
 553                         break;
 554                 case NXHERE:
 555                         exphere(redir, &fn);
 556                         break;
 557                 }
 558         }
 559 }
 560
 561
 562
 563 /*
 564  * Evaluate a pipeline.  All the processes in the pipeline are children
 565  * of the process creating the pipeline.  (This differs from some versions
 566  * of the shell, which make the last process in a pipeline the parent
 567  * of all the rest.)
 568  */
 569
 570 static void
 571 evalpipe(union node *n)
 572 {
 573         struct job *jp;
 574         struct nodelist *lp;
 575         int pipelen;
 576         int prevfd;
 577         int pip[2];
 578
 579         TRACE(("evalpipe(%p) called\n", (void *)n));
 580         pipelen = 0;
 581         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
 582                 pipelen++;
 583         INTOFF;
 584         jp = makejob(n, pipelen);
 585         prevfd = -1;
 586         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
 587                 prehash(lp->n);
 588                 pip[1] = -1;
 589                 if (lp->next) {
 590                         if (pipe(pip) < 0) {
 591                                 if (prevfd >= 0)
 592                                         close(prevfd);
 593                                 error("Pipe call failed: %s", strerror(errno));
 594                         }
 595                 }
 596                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
 597                         INTON;
 598                         if (prevfd > 0) {
 599                                 dup2(prevfd, 0);
 600                                 close(prevfd);
 601                         }
 602                         if (pip[1] >= 0) {
 603                                 if (!(prevfd >= 0 && pip[0] == 0))
 604                                         close(pip[0]);
 605                                 if (pip[1] != 1) {
 606                                         dup2(pip[1], 1);
 607                                         close(pip[1]);
 608                                 }
 609                         }
 610                         evaltree(lp->n, EV_EXIT);
 611                 }
 612                 if (prevfd >= 0)
 613                         close(prevfd);
 614                 prevfd = pip[0];
 615                 if (pip[1] != -1)
 616                         close(pip[1]);
 617         }
 618         INTON;
 619         if (n->npipe.backgnd == 0) {
 620                 INTOFF;
 621                 exitstatus = waitforjob(jp, NULL);
 622                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 623                 INTON;
 624         } else
 625                 exitstatus = 0;
 626 }
 627
 628
 629
 630 static int
 631 is_valid_fast_cmdsubst(union node *n)
 632 {
 633
 634         return (n->type == NCMD);
 635 }
 636
 637 /*
 638  * Execute a command inside back quotes.  If it's a builtin command, we
 639  * want to save its output in a block obtained from malloc.  Otherwise
 640  * we fork off a subprocess and get the output of the command via a pipe.
 641  * Should be called with interrupts off.
 642  */
 643
 644 void
 645 evalbackcmd(union node *n, struct backcmd *result)
 646 {
 647         int pip[2];
 648         struct job *jp;
 649         struct stackmark smark;
 650         struct jmploc jmploc;
 651         struct jmploc *savehandler;
 652         struct localvar *savelocalvars;
 653
 654         setstackmark(&smark);
 655         result->fd = -1;
 656         result->buf = NULL;
 657         result->nleft = 0;
 658         result->jp = NULL;
 659         if (n == NULL) {
 660                 exitstatus = 0;
 661                 goto out;
 662         }
 663         exitstatus = oexitstatus;
 664         if (is_valid_fast_cmdsubst(n)) {
 665                 savelocalvars = localvars;
 666                 localvars = NULL;
 667                 forcelocal++;
 668                 savehandler = handler;
 669                 if (setjmp(jmploc.loc)) {
 670                         if (exception == EXERROR || exception == EXEXEC)
 671                                 exitstatus = 2;
 672                         else if (exception != 0) {
 673                                 handler = savehandler;
 674                                 forcelocal--;
 675                                 poplocalvars();
 676                                 localvars = savelocalvars;
 677                                 longjmp(handler->loc, 1);
 678                         }
 679                 } else {
 680                         handler = &jmploc;
 681                         evalcommand(n, EV_BACKCMD, result);
 682                 }
 683                 handler = savehandler;
 684                 forcelocal--;
 685                 poplocalvars();
 686                 localvars = savelocalvars;
 687         } else {
 688                 if (pipe(pip) < 0)
 689                         error("Pipe call failed: %s", strerror(errno));
 690                 jp = makejob(n, 1);
 691                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 692                         FORCEINTON;
 693                         close(pip[0]);
 694                         if (pip[1] != 1) {
 695                                 dup2(pip[1], 1);
 696                                 close(pip[1]);
 697                         }
 698                         evaltree(n, EV_EXIT);
 699                 }
 700                 close(pip[1]);
 701                 result->fd = pip[0];
 702                 result->jp = jp;
 703         }
 704 out:
 705         popstackmark(&smark);
 706         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 707                 result->fd, result->buf, result->nleft, result->jp));
 708 }
 709
 710 static int
 711 mustexpandto(const char *argtext, const char *mask)
 712 {
 713         for (;;) {
 714                 if (*argtext == CTLQUOTEMARK || *argtext == CTLQUOTEEND) {
 715                         argtext++;
 716                         continue;
 717                 }
 718                 if (*argtext == CTLESC)
 719                         argtext++;
 720                 else if (BASESYNTAX[(int)*argtext] == CCTL)
 721                         return (0);
 722                 if (*argtext != *mask)
 723                         return (0);
 724                 if (*argtext == '\0')
 725                         return (1);
 726                 argtext++;
 727                 mask++;
 728         }
 729 }
 730
 731 static int
 732 isdeclarationcmd(struct narg *arg)
 733 {
 734         int have_command = 0;
 735
 736         if (arg == NULL)
 737                 return (0);
 738         while (mustexpandto(arg->text, "command")) {
 739                 have_command = 1;
 740                 arg = &arg->next->narg;
 741                 if (arg == NULL)
 742                         return (0);
 743                 /*
 744                  * To also allow "command -p" and "command --" as part of
 745                  * a declaration command, add code here.
 746                  * We do not do this, as ksh does not do it either and it
 747                  * is not required by POSIX.
 748                  */
 749         }
 750         return (mustexpandto(arg->text, "export") ||
 751             mustexpandto(arg->text, "readonly") ||
 752             (mustexpandto(arg->text, "local") &&
 753                 (have_command || !isfunc("local"))));
 754 }
 755
 756 /*
 757  * Check if a builtin can safely be executed in the same process,
 758  * even though it should be in a subshell (command substitution).
 759  * Note that jobid, jobs, times and trap can show information not
 760  * available in a child process; this is deliberate.
 761  * The arguments should already have been expanded.
 762  */
 763 static int
 764 safe_builtin(int idx, int argc, char **argv)
 765 {
 766         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
 767             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
 768             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
 769             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
 770             idx == TYPECMD)
 771                 return (1);
 772         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 773             idx == UMASKCMD)
 774                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 775         if (idx == SETCMD)
 776                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 777                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 778                     argv[1][2] == '\0'));
 779         return (0);
 780 }
 781
 782 /*
 783  * Execute a simple command.
 784  * Note: This may or may not return if (flags & EV_EXIT).
 785  */
 786
 787 static void
 788 evalcommand(union node *cmd, int flgs, struct backcmd *backcmd)
 789 {
 790         union node *argp;
 791         struct arglist arglist;
 792         struct arglist varlist;
 793         volatile int flags = flgs;
 794         char **volatile argv;
 795         volatile int argc;
 796         char **envp;
 797         int varflag;
 798         struct strlist *sp;
 799         int mode;
 800         int pip[2];
 801         struct cmdentry cmdentry;
 802         struct job *volatile jp;
 803         struct jmploc jmploc;
 804         struct jmploc *savehandler;
 805         const char *savecmdname;
 806         struct shparam saveparam;
 807         struct localvar *savelocalvars;
 808         struct parsefile *savetopfile;
 809         volatile int e;
 810         char *volatile lastarg;
 811         int realstatus;
 812         volatile int do_clearcmdentry;
 813         const char *path = pathval();
 814
 815         /* First expand the arguments. */
 816         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 817         arglist.lastp = &arglist.list;
 818         varlist.lastp = &varlist.list;
 819         varflag = 1;
 820         jp = NULL;
 821         do_clearcmdentry = 0;
 822         oexitstatus = exitstatus;
 823         exitstatus = 0;
 824         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 825                 if (varflag && isassignment(argp->narg.text)) {
 826                         expandarg(argp, varflag == 1 ? &varlist : &arglist,
 827                             EXP_VARTILDE);
 828                         continue;
 829                 } else if (varflag == 1)
 830                         varflag = isdeclarationcmd(&argp->narg) ? 2 : 0;
 831                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 832         }
 833         *arglist.lastp = NULL;
 834         *varlist.lastp = NULL;
 835         expredir(cmd->ncmd.redirect);
 836         argc = 0;
 837         for (sp = arglist.list ; sp ; sp = sp->next)
 838                 argc++;
 839         /* Add one slot at the beginning for tryexec(). */
 840         argv = stalloc(sizeof (char *) * (argc + 2));
 841         argv++;
 842
 843         for (sp = arglist.list ; sp ; sp = sp->next) {
 844                 TRACE(("evalcommand arg: %s\n", sp->text));
 845                 *argv++ = sp->text;
 846         }
 847         *argv = NULL;
 848         lastarg = NULL;
 849         if (iflag && funcnest == 0 && argc > 0)
 850                 lastarg = argv[-1];
 851         argv -= argc;
 852
 853         /* Print the command if xflag is set. */
 854         if (xflag) {
 855                 char sep = 0;
 856                 const char *p, *ps4;
 857                 ps4 = expandstr(ps4val());
 858                 out2str(ps4 != NULL ? ps4 : ps4val());
 859                 for (sp = varlist.list ; sp ; sp = sp->next) {
 860                         if (sep != 0)
 861                                 out2c(' ');
 862                         p = strchr(sp->text, '=');
 863                         if (p != NULL) {
 864                                 p++;
 865                                 outbin(sp->text, p - sp->text, out2);
 866                                 out2qstr(p);
 867                         } else
 868                                 out2qstr(sp->text);
 869                         sep = ' ';
 870                 }
 871                 for (sp = arglist.list ; sp ; sp = sp->next) {
 872                         if (sep != 0)
 873                                 out2c(' ');
 874                         /* Disambiguate command looking like assignment. */
 875                         if (sp == arglist.list &&
 876                                         strchr(sp->text, '=') != NULL &&
 877                                         strchr(sp->text, '\'') == NULL) {
 878                                 out2c('\'');
 879                                 out2str(sp->text);
 880                                 out2c('\'');
 881                         } else
 882                                 out2qstr(sp->text);
 883                         sep = ' ';
 884                 }
 885                 out2c('\n');
 886                 flushout(&errout);
 887         }
 888
 889         /* Now locate the command. */
 890         if (argc == 0) {
 891                 /* Variable assignment(s) without command */
 892                 cmdentry.cmdtype = CMDBUILTIN;
 893                 cmdentry.u.index = BLTINCMD;
 894                 cmdentry.special = 0;
 895         } else {
 896                 static const char PATH[] = "PATH=";
 897                 int cmd_flags = 0, bltinonly = 0;
 898
 899                 /*
 900                  * Modify the command lookup path, if a PATH= assignment
 901                  * is present
 902                  */
 903                 for (sp = varlist.list ; sp ; sp = sp->next)
 904                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 905                                 path = sp->text + sizeof(PATH) - 1;
 906                                 /*
 907                                  * On `PATH=... command`, we need to make
 908                                  * sure that the command isn't using the
 909                                  * non-updated hash table of the outer PATH
 910                                  * setting and we need to make sure that
 911                                  * the hash table isn't filled with items
 912                                  * from the temporary setting.
 913                                  *
 914                                  * It would be better to forbit using and
 915                                  * updating the table while this command
 916                                  * runs, by the command finding mechanism
 917                                  * is heavily integrated with hash handling,
 918                                  * so we just delete the hash before and after
 919                                  * the command runs. Partly deleting like
 920                                  * changepatch() does doesn't seem worth the
 921                                  * bookinging effort, since most such runs add
 922                                  * directories in front of the new PATH.
 923                                  */
 924                                 clearcmdentry();
 925                                 do_clearcmdentry = 1;
 926                         }
 927
 928                 for (;;) {
 929                         if (bltinonly) {
 930                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 931                                 if (cmdentry.u.index < 0) {
 932                                         cmdentry.u.index = BLTINCMD;
 933                                         argv--;
 934                                         argc++;
 935                                         break;
 936                                 }
 937                         } else
 938                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 939                         /* implement the bltin and command builtins here */
 940                         if (cmdentry.cmdtype != CMDBUILTIN)
 941                                 break;
 942                         if (cmdentry.u.index == BLTINCMD) {
 943                                 if (argc == 1)
 944                                         break;
 945                                 argv++;
 946                                 argc--;
 947                                 bltinonly = 1;
 948                         } else if (cmdentry.u.index == COMMANDCMD) {
 949                                 if (argc == 1)
 950                                         break;
 951                                 if (!strcmp(argv[1], "-p")) {
 952                                         if (argc == 2)
 953                                                 break;
 954                                         if (argv[2][0] == '-') {
 955                                                 if (strcmp(argv[2], "--"))
 956                                                         break;
 957                                                 if (argc == 3)
 958                                                         break;
 959                                                 argv += 3;
 960                                                 argc -= 3;
 961                                         } else {
 962                                                 argv += 2;
 963                                                 argc -= 2;
 964                                         }
 965                                         path = _PATH_STDPATH;
 966                                         clearcmdentry();
 967                                         do_clearcmdentry = 1;
 968                                 } else if (!strcmp(argv[1], "--")) {
 969                                         if (argc == 2)
 970                                                 break;
 971                                         argv += 2;
 972                                         argc -= 2;
 973                                 } else if (argv[1][0] == '-')
 974                                         break;
 975                                 else {
 976                                         argv++;
 977                                         argc--;
 978                                 }
 979                                 cmd_flags |= DO_NOFUNC;
 980                                 bltinonly = 0;
 981                         } else
 982                                 break;
 983                 }
 984                 /*
 985                  * Special builtins lose their special properties when
 986                  * called via 'command'.
 987                  */
 988                 if (cmd_flags & DO_NOFUNC)
 989                         cmdentry.special = 0;
 990         }
 991
 992         /* Fork off a child process if necessary. */
 993         if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 994             && ((flags & EV_EXIT) == 0 || have_traps()))
 995          || ((flags & EV_BACKCMD) != 0
 996             && (cmdentry.cmdtype != CMDBUILTIN ||
 997                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 998                 jp = makejob(cmd, 1);
 999                 mode = FORK_FG;
1000                 if (flags & EV_BACKCMD) {
1001                         mode = FORK_NOJOB;
1002                         if (pipe(pip) < 0)
1003                                 error("Pipe call failed: %s", strerror(errno));
1004                 }
1005                 if (cmdentry.cmdtype == CMDNORMAL &&
1006                     cmd->ncmd.redirect == NULL &&
1007                     varlist.list == NULL &&
1008                     (mode == FORK_FG || mode == FORK_NOJOB) &&
1009                     !disvforkset() && !iflag && !mflag) {
1010                         vforkexecshell(jp, argv, environment(), path,
1011                             cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL);
1012                         goto parent;
1013                 }
1014                 if (forkshell(jp, cmd, mode) != 0)
1015                         goto parent;    /* at end of routine */
1016                 if (flags & EV_BACKCMD) {
1017                         FORCEINTON;
1018                         close(pip[0]);
1019                         if (pip[1] != 1) {
1020                                 dup2(pip[1], 1);
1021                                 close(pip[1]);
1022                         }
1023                         flags &= ~EV_BACKCMD;
1024                 }
1025                 flags |= EV_EXIT;
1026         }
1027
1028         /* This is the child process if a fork occurred. */
1029         /* Execute the command. */
1030         if (cmdentry.cmdtype == CMDFUNCTION) {
1031 #ifdef DEBUG
1032                 trputs("Shell function:  ");  trargs(argv);
1033 #endif
1034                 saveparam = shellparam;
1035                 shellparam.malloc = 0;
1036                 shellparam.reset = 1;
1037                 shellparam.nparam = argc - 1;
1038                 shellparam.p = argv + 1;
1039                 shellparam.optnext = NULL;
1040                 INTOFF;
1041                 savelocalvars = localvars;
1042                 localvars = NULL;
1043                 reffunc(cmdentry.u.func);
1044                 savehandler = handler;
1045                 if (setjmp(jmploc.loc)) {
1046                         freeparam(&shellparam);
1047                         shellparam = saveparam;
1048                         popredir();
1049                         unreffunc(cmdentry.u.func);
1050                         poplocalvars();
1051                         localvars = savelocalvars;
1052                         funcnest--;
1053                         handler = savehandler;
1054                         longjmp(handler->loc, 1);
1055                 }
1056                 handler = &jmploc;
1057                 funcnest++;
1058                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
1059                 INTON;
1060                 for (sp = varlist.list ; sp ; sp = sp->next)
1061                         mklocal(sp->text);
1062                 exitstatus = oexitstatus;
1063                 evaltree(getfuncnode(cmdentry.u.func),
1064                     flags & (EV_TESTED | EV_EXIT));
1065                 INTOFF;
1066                 unreffunc(cmdentry.u.func);
1067                 poplocalvars();
1068                 localvars = savelocalvars;
1069                 freeparam(&shellparam);
1070                 shellparam = saveparam;
1071                 handler = savehandler;
1072                 funcnest--;
1073                 popredir();
1074                 INTON;
1075                 if (evalskip == SKIPFUNC) {
1076                         evalskip = 0;
1077                         skipcount = 0;
1078                 }
1079                 if (jp)
1080                         exitshell(exitstatus);
1081         } else if (cmdentry.cmdtype == CMDBUILTIN) {
1082 #ifdef DEBUG
1083                 trputs("builtin command:  ");  trargs(argv);
1084 #endif
1085                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
1086                 if (flags == EV_BACKCMD) {
1087                         memout.nleft = 0;
1088                         memout.nextc = memout.buf;
1089                         memout.bufsize = 64;
1090                         mode |= REDIR_BACKQ;
1091                 }
1092                 savecmdname = commandname;
1093                 savetopfile = getcurrentfile();
1094                 cmdenviron = varlist.list;
1095                 e = -1;
1096                 savehandler = handler;
1097                 if (setjmp(jmploc.loc)) {
1098                         e = exception;
1099                         if (e == EXINT)
1100                                 exitstatus = SIGINT+128;
1101                         else if (e != EXEXIT)
1102                                 exitstatus = 2;
1103                         goto cmddone;
1104                 }
1105                 handler = &jmploc;
1106                 redirect(cmd->ncmd.redirect, mode);
1107                 outclearerror(out1);
1108                 /*
1109                  * If there is no command word, redirection errors should
1110                  * not be fatal but assignment errors should.
1111                  */
1112                 if (argc == 0)
1113                         cmdentry.special = 1;
1114                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1115                 if (argc > 0)
1116                         bltinsetlocale();
1117                 commandname = argv[0];
1118                 argptr = argv + 1;
1119                 nextopt_optptr = NULL;          /* initialize nextopt */
1120                 builtin_flags = flags;
1121                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1122                 flushall();
1123                 if (outiserror(out1)) {
1124                         warning("write error on stdout");
1125                         if (exitstatus == 0 || exitstatus == 1)
1126                                 exitstatus = 2;
1127                 }
1128 cmddone:
1129                 if (argc > 0)
1130                         bltinunsetlocale();
1131                 cmdenviron = NULL;
1132                 out1 = &output;
1133                 out2 = &errout;
1134                 freestdout();
1135                 handler = savehandler;
1136                 commandname = savecmdname;
1137                 if (jp)
1138                         exitshell(exitstatus);
1139                 if (flags == EV_BACKCMD) {
1140                         backcmd->buf = memout.buf;
1141                         backcmd->nleft = memout.nextc - memout.buf;
1142                         memout.buf = NULL;
1143                 }
1144                 if (cmdentry.u.index != EXECCMD)
1145                         popredir();
1146                 if (e != -1) {
1147                         if ((e != EXERROR && e != EXEXEC)
1148                             || cmdentry.special)
1149                                 exraise(e);
1150                         popfilesupto(savetopfile);
1151                         if (flags != EV_BACKCMD)
1152                                 FORCEINTON;
1153                 }
1154         } else {
1155 #ifdef DEBUG
1156                 trputs("normal command:  ");  trargs(argv);
1157 #endif
1158                 redirect(cmd->ncmd.redirect, 0);
1159                 for (sp = varlist.list ; sp ; sp = sp->next)
1160                         setvareq(sp->text, VEXPORT|VSTACK);
1161                 envp = environment();
1162                 shellexec(argv, envp, path, cmdentry.u.index);
1163                 /*NOTREACHED*/
1164         }
1165         goto out;
1166
1167 parent: /* parent process gets here (if we forked) */
1168         if (mode == FORK_FG) {  /* argument to fork */
1169                 INTOFF;
1170                 exitstatus = waitforjob(jp, &realstatus);
1171                 INTON;
1172                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1173                         evalskip = SKIPBREAK;
1174                         skipcount = loopnest;
1175                 }
1176         } else if (mode == FORK_NOJOB) {
1177                 backcmd->fd = pip[0];
1178                 close(pip[1]);
1179                 backcmd->jp = jp;
1180         }
1181
1182 out:
1183         if (lastarg)
1184                 setvar("_", lastarg, 0);
1185         if (do_clearcmdentry)
1186                 clearcmdentry();
1187 }
1188
1189
1190
1191 /*
1192  * Search for a command.  This is called before we fork so that the
1193  * location of the command will be available in the parent as well as
1194  * the child.  The check for "goodname" is an overly conservative
1195  * check that the name will not be subject to expansion.
1196  */
1197
1198 static void
1199 prehash(union node *n)
1200 {
1201         struct cmdentry entry;
1202
1203         if (n && n->type == NCMD && n->ncmd.args)
1204                 if (goodname(n->ncmd.args->narg.text))
1205                         find_command(n->ncmd.args->narg.text, &entry, 0,
1206                                      pathval());
1207 }
1208
1209
1210
1211 /*
1212  * Builtin commands.  Builtin commands whose functions are closely
1213  * tied to evaluation are implemented here.
1214  */
1215
1216 /*
1217  * No command given, a bltin command with no arguments, or a bltin command
1218  * with an invalid name.
1219  */
1220
1221 int
1222 bltincmd(int argc, char **argv)
1223 {
1224         if (argc > 1) {
1225                 out2fmt_flush("%s: not found\n", argv[1]);
1226                 return 127;
1227         }
1228         /*
1229          * Preserve exitstatus of a previous possible redirection
1230          * as POSIX mandates
1231          */
1232         return exitstatus;
1233 }
1234
1235
1236 /*
1237  * Handle break and continue commands.  Break, continue, and return are
1238  * all handled by setting the evalskip flag.  The evaluation routines
1239  * above all check this flag, and if it is set they start skipping
1240  * commands rather than executing them.  The variable skipcount is
1241  * the number of loops to break/continue, or the number of function
1242  * levels to return.  (The latter is always 1.)  It should probably
1243  * be an error to break out of more loops than exist, but it isn't
1244  * in the standard shell so we don't make it one here.
1245  */
1246
1247 int
1248 breakcmd(int argc, char **argv)
1249 {
1250         int n = argc > 1 ? number(argv[1]) : 1;
1251
1252         if (n > loopnest)
1253                 n = loopnest;
1254         if (n > 0) {
1255                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1256                 skipcount = n;
1257         }
1258         return 0;
1259 }
1260
1261 /*
1262  * The `command' command.
1263  */
1264 int
1265 commandcmd(int argc __unused, char **argv __unused)
1266 {
1267         const char *path;
1268         int ch;
1269         int cmd = -1;
1270
1271         path = bltinlookup("PATH", 1);
1272
1273         while ((ch = nextopt("pvV")) != '\0') {
1274                 switch (ch) {
1275                 case 'p':
1276                         path = _PATH_STDPATH;
1277                         break;
1278                 case 'v':
1279                         cmd = TYPECMD_SMALLV;
1280                         break;
1281                 case 'V':
1282                         cmd = TYPECMD_BIGV;
1283                         break;
1284                 }
1285         }
1286
1287         if (cmd != -1) {
1288                 if (*argptr == NULL || argptr[1] != NULL)
1289                         error("wrong number of arguments");
1290                 return typecmd_impl(2, argptr - 1, cmd, path);
1291         }
1292         if (*argptr != NULL)
1293                 error("commandcmd bad call");
1294
1295         /*
1296          * Do nothing successfully if no command was specified;
1297          * ksh also does this.
1298          */
1299         return(0);
1300 }
1301
1302
1303 /*
1304  * The return command.
1305  */
1306
1307 int
1308 returncmd(int argc, char **argv)
1309 {
1310         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1311
1312         if (funcnest) {
1313                 evalskip = SKIPFUNC;
1314                 skipcount = 1;
1315         } else {
1316                 /* skip the rest of the file */
1317                 evalskip = SKIPFILE;
1318                 skipcount = 1;
1319         }
1320         return ret;
1321 }
1322
1323
1324 int
1325 falsecmd(int argc __unused, char **argv __unused)
1326 {
1327         return 1;
1328 }
1329
1330
1331 int
1332 truecmd(int argc __unused, char **argv __unused)
1333 {
1334         return 0;
1335 }
1336
1337
1338 int
1339 execcmd(int argc, char **argv)
1340 {
1341         /*
1342          * Because we have historically not supported any options,
1343          * only treat "--" specially.
1344          */
1345         if (argc > 1 && strcmp(argv[1], "--") == 0)
1346                 argc--, argv++;
1347         if (argc > 1) {
1348                 struct strlist *sp;
1349
1350                 iflag = 0;              /* exit on error */
1351                 mflag = 0;
1352                 optschanged();
1353                 for (sp = cmdenviron; sp ; sp = sp->next)
1354                         setvareq(sp->text, VEXPORT|VSTACK);
1355                 shellexec(argv + 1, environment(), pathval(), 0);
1356
1357         }
1358         return 0;
1359 }
1360
1361
1362 int
1363 timescmd(int argc __unused, char **argv __unused)
1364 {
1365         struct rusage ru;
1366         long shumins, shsmins, chumins, chsmins;
1367         double shusecs, shssecs, chusecs, chssecs;
1368
1369         if (getrusage(RUSAGE_SELF, &ru) < 0)
1370                 return 1;
1371         shumins = ru.ru_utime.tv_sec / 60;
1372         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1373         shsmins = ru.ru_stime.tv_sec / 60;
1374         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1375         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1376                 return 1;
1377         chumins = ru.ru_utime.tv_sec / 60;
1378         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1379         chsmins = ru.ru_stime.tv_sec / 60;
1380         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1381         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1382             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1383         return 0;
1384 }