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. 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 <errno.h>
  47
  48 /*
  49  * Evaluate a command.
  50  */
  51
  52 #include "shell.h"
  53 #include "nodes.h"
  54 #include "syntax.h"
  55 #include "expand.h"
  56 #include "parser.h"
  57 #include "jobs.h"
  58 #include "eval.h"
  59 #include "builtins.h"
  60 #include "options.h"
  61 #include "exec.h"
  62 #include "redir.h"
  63 #include "input.h"
  64 #include "output.h"
  65 #include "trap.h"
  66 #include "var.h"
  67 #include "memalloc.h"
  68 #include "error.h"
  69 #include "show.h"
  70 #include "mystring.h"
  71 #ifndef NO_HISTORY
  72 #include "myhistedit.h"
  73 #endif
  74
  75
  76 int evalskip;                   /* set if we are skipping commands */
  77 int skipcount;                  /* number of levels to skip */
  78 static int loopnest;            /* current loop nesting level */
  79 int funcnest;                   /* depth of function calls */
  80 static int builtin_flags;       /* evalcommand flags for builtins */
  81
  82
  83 char *commandname;
  84 struct arglist *cmdenviron;
  85 int exitstatus;                 /* exit status of last command */
  86 int oexitstatus;                /* saved exit status */
  87
  88
  89 static void evalloop(union node *, int);
  90 static void evalfor(union node *, int);
  91 static union node *evalcase(union node *);
  92 static void evalsubshell(union node *, int);
  93 static void evalredir(union node *, int);
  94 static void exphere(union node *, struct arglist *);
  95 static void expredir(union node *);
  96 static void evalpipe(union node *);
  97 static int is_valid_fast_cmdsubst(union node *n);
  98 static void evalcommand(union node *, int, struct backcmd *);
  99 static void prehash(union node *);
 100
 101
 102 /*
 103  * Called to reset things after an exception.
 104  */
 105
 106 void
 107 reseteval(void)
 108 {
 109         evalskip = 0;
 110         loopnest = 0;
 111 }
 112
 113
 114 /*
 115  * The eval command.
 116  */
 117
 118 int
 119 evalcmd(int argc, char **argv)
 120 {
 121         char *p;
 122         char *concat;
 123         char **ap;
 124
 125         if (argc > 1) {
 126                 p = argv[1];
 127                 if (argc > 2) {
 128                         STARTSTACKSTR(concat);
 129                         ap = argv + 2;
 130                         for (;;) {
 131                                 STPUTS(p, concat);
 132                                 if ((p = *ap++) == NULL)
 133                                         break;
 134                                 STPUTC(' ', concat);
 135                         }
 136                         STPUTC('\0', concat);
 137                         p = grabstackstr(concat);
 138                 }
 139                 evalstring(p, builtin_flags);
 140         } else
 141                 exitstatus = 0;
 142         return exitstatus;
 143 }
 144
 145
 146 /*
 147  * Execute a command or commands contained in a string.
 148  */
 149
 150 void
 151 evalstring(const char *s, int flags)
 152 {
 153         union node *n;
 154         struct stackmark smark;
 155         int flags_exit;
 156         int any;
 157
 158         flags_exit = flags & EV_EXIT;
 159         flags &= ~EV_EXIT;
 160         any = 0;
 161         setstackmark(&smark);
 162         setinputstring(s, 1);
 163         while ((n = parsecmd(0)) != NEOF) {
 164                 if (n != NULL && !nflag) {
 165                         if (flags_exit && preadateof())
 166                                 evaltree(n, flags | EV_EXIT);
 167                         else
 168                                 evaltree(n, flags);
 169                         any = 1;
 170                         if (evalskip)
 171                                 break;
 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                 if (!evalskip)
 321                         evaltree(n->nbinary.ch1, EV_TESTED);
 322                 if (evalskip) {
 323                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 324                                 evalskip = 0;
 325                                 continue;
 326                         }
 327                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 328                                 evalskip = 0;
 329                         if (evalskip == SKIPRETURN)
 330                                 status = exitstatus;
 331                         break;
 332                 }
 333                 if (n->type == NWHILE) {
 334                         if (exitstatus != 0)
 335                                 break;
 336                 } else {
 337                         if (exitstatus == 0)
 338                                 break;
 339                 }
 340                 evaltree(n->nbinary.ch2, flags);
 341                 status = exitstatus;
 342         }
 343         loopnest--;
 344         exitstatus = status;
 345 }
 346
 347
 348
 349 static void
 350 evalfor(union node *n, int flags)
 351 {
 352         struct arglist arglist;
 353         union node *argp;
 354         int i;
 355         int status;
 356
 357         emptyarglist(&arglist);
 358         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 359                 oexitstatus = exitstatus;
 360                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 361         }
 362
 363         loopnest++;
 364         status = 0;
 365         for (i = 0; i < arglist.count; i++) {
 366                 setvar(n->nfor.var, arglist.args[i], 0);
 367                 evaltree(n->nfor.body, flags);
 368                 status = exitstatus;
 369                 if (evalskip) {
 370                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 371                                 evalskip = 0;
 372                                 continue;
 373                         }
 374                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 375                                 evalskip = 0;
 376                         break;
 377                 }
 378         }
 379         loopnest--;
 380         exitstatus = status;
 381 }
 382
 383
 384 /*
 385  * Evaluate a case statement, returning the selected tree.
 386  *
 387  * The exit status needs care to get right.
 388  */
 389
 390 static union node *
 391 evalcase(union node *n)
 392 {
 393         union node *cp;
 394         union node *patp;
 395         struct arglist arglist;
 396
 397         emptyarglist(&arglist);
 398         oexitstatus = exitstatus;
 399         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 400         for (cp = n->ncase.cases ; cp ; cp = cp->nclist.next) {
 401                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 402                         if (casematch(patp, arglist.args[0])) {
 403                                 while (cp->nclist.next &&
 404                                     cp->type == NCLISTFALLTHRU &&
 405                                     cp->nclist.body == NULL)
 406                                         cp = cp->nclist.next;
 407                                 if (cp->nclist.next &&
 408                                     cp->type == NCLISTFALLTHRU)
 409                                         return (cp);
 410                                 if (cp->nclist.body == NULL)
 411                                         exitstatus = 0;
 412                                 return (cp->nclist.body);
 413                         }
 414                 }
 415         }
 416         exitstatus = 0;
 417         return (NULL);
 418 }
 419
 420
 421
 422 /*
 423  * Kick off a subshell to evaluate a tree.
 424  */
 425
 426 static void
 427 evalsubshell(union node *n, int flags)
 428 {
 429         struct job *jp;
 430         int backgnd = (n->type == NBACKGND);
 431
 432         oexitstatus = exitstatus;
 433         expredir(n->nredir.redirect);
 434         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
 435                         forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
 436                 if (backgnd)
 437                         flags &=~ EV_TESTED;
 438                 redirect(n->nredir.redirect, 0);
 439                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 440         } else if (! backgnd) {
 441                 INTOFF;
 442                 exitstatus = waitforjob(jp, (int *)NULL);
 443                 INTON;
 444         } else
 445                 exitstatus = 0;
 446 }
 447
 448
 449 /*
 450  * Evaluate a redirected compound command.
 451  */
 452
 453 static void
 454 evalredir(union node *n, int flags)
 455 {
 456         struct jmploc jmploc;
 457         struct jmploc *savehandler;
 458         volatile int in_redirect = 1;
 459
 460         oexitstatus = exitstatus;
 461         expredir(n->nredir.redirect);
 462         savehandler = handler;
 463         if (setjmp(jmploc.loc)) {
 464                 int e;
 465
 466                 handler = savehandler;
 467                 e = exception;
 468                 popredir();
 469                 if (e == EXERROR || e == EXEXEC) {
 470                         if (in_redirect) {
 471                                 exitstatus = 2;
 472                                 FORCEINTON;
 473                                 return;
 474                         }
 475                 }
 476                 longjmp(handler->loc, 1);
 477         } else {
 478                 INTOFF;
 479                 handler = &jmploc;
 480                 redirect(n->nredir.redirect, REDIR_PUSH);
 481                 in_redirect = 0;
 482                 INTON;
 483                 evaltree(n->nredir.n, flags);
 484         }
 485         INTOFF;
 486         handler = savehandler;
 487         popredir();
 488         INTON;
 489 }
 490
 491
 492 static void
 493 exphere(union node *redir, struct arglist *fn)
 494 {
 495         struct jmploc jmploc;
 496         struct jmploc *savehandler;
 497         struct localvar *savelocalvars;
 498         int need_longjmp = 0;
 499         unsigned char saveoptreset;
 500
 501         redir->nhere.expdoc = "";
 502         savelocalvars = localvars;
 503         localvars = NULL;
 504         saveoptreset = shellparam.reset;
 505         forcelocal++;
 506         savehandler = handler;
 507         if (setjmp(jmploc.loc))
 508                 need_longjmp = exception != EXERROR && exception != EXEXEC;
 509         else {
 510                 handler = &jmploc;
 511                 expandarg(redir->nhere.doc, fn, 0);
 512                 redir->nhere.expdoc = fn->args[0];
 513                 INTOFF;
 514         }
 515         handler = savehandler;
 516         forcelocal--;
 517         poplocalvars();
 518         localvars = savelocalvars;
 519         shellparam.reset = saveoptreset;
 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                 emptyarglist(&fn);
 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);
 545                         redir->nfile.expfname = fn.args[0];
 546                         break;
 547                 case NFROMFD:
 548                 case NTOFD:
 549                         if (redir->ndup.vname) {
 550                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE);
 551                                 fixredir(redir, fn.args[0], 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, (int *)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         unsigned char saveoptreset;
 654
 655         result->fd = -1;
 656         result->buf = NULL;
 657         result->nleft = 0;
 658         result->jp = NULL;
 659         if (n == NULL) {
 660                 exitstatus = 0;
 661                 return;
 662         }
 663         setstackmark(&smark);
 664         exitstatus = oexitstatus;
 665         if (is_valid_fast_cmdsubst(n)) {
 666                 savelocalvars = localvars;
 667                 localvars = NULL;
 668                 saveoptreset = shellparam.reset;
 669                 forcelocal++;
 670                 savehandler = handler;
 671                 if (setjmp(jmploc.loc)) {
 672                         if (exception == EXERROR || exception == EXEXEC)
 673                                 exitstatus = 2;
 674                         else if (exception != 0) {
 675                                 handler = savehandler;
 676                                 forcelocal--;
 677                                 poplocalvars();
 678                                 localvars = savelocalvars;
 679                                 shellparam.reset = saveoptreset;
 680                                 longjmp(handler->loc, 1);
 681                         }
 682                 } else {
 683                         handler = &jmploc;
 684                         evalcommand(n, EV_BACKCMD, result);
 685                 }
 686                 handler = savehandler;
 687                 forcelocal--;
 688                 poplocalvars();
 689                 localvars = savelocalvars;
 690                 shellparam.reset = saveoptreset;
 691         } else {
 692                 if (pipe(pip) < 0)
 693                         error("Pipe call failed: %s", strerror(errno));
 694                 jp = makejob(n, 1);
 695                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 696                         FORCEINTON;
 697                         close(pip[0]);
 698                         if (pip[1] != 1) {
 699                                 dup2(pip[1], 1);
 700                                 close(pip[1]);
 701                         }
 702                         evaltree(n, EV_EXIT);
 703                 }
 704                 close(pip[1]);
 705                 result->fd = pip[0];
 706                 result->jp = jp;
 707         }
 708         popstackmark(&smark);
 709         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 710                 result->fd, result->buf, result->nleft, result->jp));
 711 }
 712
 713 static int
 714 mustexpandto(const char *argtext, const char *mask)
 715 {
 716         for (;;) {
 717                 if (*argtext == CTLQUOTEMARK || *argtext == CTLQUOTEEND) {
 718                         argtext++;
 719                         continue;
 720                 }
 721                 if (*argtext == CTLESC)
 722                         argtext++;
 723                 else if (BASESYNTAX[(int)*argtext] == CCTL)
 724                         return (0);
 725                 if (*argtext != *mask)
 726                         return (0);
 727                 if (*argtext == '\0')
 728                         return (1);
 729                 argtext++;
 730                 mask++;
 731         }
 732 }
 733
 734 static int
 735 isdeclarationcmd(struct narg *arg)
 736 {
 737         int have_command = 0;
 738
 739         if (arg == NULL)
 740                 return (0);
 741         while (mustexpandto(arg->text, "command")) {
 742                 have_command = 1;
 743                 arg = &arg->next->narg;
 744                 if (arg == NULL)
 745                         return (0);
 746                 /*
 747                  * To also allow "command -p" and "command --" as part of
 748                  * a declaration command, add code here.
 749                  * We do not do this, as ksh does not do it either and it
 750                  * is not required by POSIX.
 751                  */
 752         }
 753         return (mustexpandto(arg->text, "export") ||
 754             mustexpandto(arg->text, "readonly") ||
 755             (mustexpandto(arg->text, "local") &&
 756                 (have_command || !isfunc("local"))));
 757 }
 758
 759 static void
 760 xtracecommand(struct arglist *varlist, int argc, char **argv)
 761 {
 762         char sep = 0;
 763         const char *text, *p, *ps4;
 764         int i;
 765
 766         ps4 = expandstr(ps4val());
 767         out2str(ps4 != NULL ? ps4 : ps4val());
 768         for (i = 0; i < varlist->count; i++) {
 769                 text = varlist->args[i];
 770                 if (sep != 0)
 771                         out2c(' ');
 772                 p = strchr(text, '=');
 773                 if (p != NULL) {
 774                         p++;
 775                         outbin(text, p - text, out2);
 776                         out2qstr(p);
 777                 } else
 778                         out2qstr(text);
 779                 sep = ' ';
 780         }
 781         for (i = 0; i < argc; i++) {
 782                 text = argv[i];
 783                 if (sep != 0)
 784                         out2c(' ');
 785                 out2qstr(text);
 786                 sep = ' ';
 787         }
 788         out2c('\n');
 789         flushout(&errout);
 790 }
 791
 792 /*
 793  * Check if a builtin can safely be executed in the same process,
 794  * even though it should be in a subshell (command substitution).
 795  * Note that jobid, jobs, times and trap can show information not
 796  * available in a child process; this is deliberate.
 797  * The arguments should already have been expanded.
 798  */
 799 static int
 800 safe_builtin(int idx, int argc, char **argv)
 801 {
 802         /* Generated from builtins.def. */
 803         if (safe_builtin_always(idx))
 804                 return (1);
 805         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 806             idx == UMASKCMD)
 807                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 808         if (idx == SETCMD)
 809                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 810                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 811                     argv[1][2] == '\0'));
 812         return (0);
 813 }
 814
 815 /*
 816  * Execute a simple command.
 817  * Note: This may or may not return if (flags & EV_EXIT).
 818  */
 819
 820 static void
 821 evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
 822 {
 823         union node *argp;
 824         struct arglist arglist;
 825         struct arglist varlist;
 826         char **argv;
 827         int argc;
 828         char **envp;
 829         int varflag;
 830         int mode;
 831         int pip[2];
 832         struct cmdentry cmdentry;
 833         struct job *jp;
 834         struct jmploc jmploc;
 835         struct jmploc *savehandler;
 836         char *savecmdname;
 837         struct shparam saveparam;
 838         struct localvar *savelocalvars;
 839         struct parsefile *savetopfile;
 840         volatile int e;
 841         char *lastarg;
 842         int signaled;
 843         int do_clearcmdentry;
 844         const char *path = pathval();
 845         int i;
 846
 847         /* First expand the arguments. */
 848         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 849         emptyarglist(&arglist);
 850         emptyarglist(&varlist);
 851         varflag = 1;
 852         jp = NULL;
 853         do_clearcmdentry = 0;
 854         oexitstatus = exitstatus;
 855         exitstatus = 0;
 856         /* Add one slot at the beginning for tryexec(). */
 857         appendarglist(&arglist, nullstr);
 858         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 859                 if (varflag && isassignment(argp->narg.text)) {
 860                         expandarg(argp, varflag == 1 ? &varlist : &arglist,
 861                             EXP_VARTILDE);
 862                         continue;
 863                 } else if (varflag == 1)
 864                         varflag = isdeclarationcmd(&argp->narg) ? 2 : 0;
 865                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 866         }
 867         appendarglist(&arglist, nullstr);
 868         expredir(cmd->ncmd.redirect);
 869         argc = arglist.count - 2;
 870         argv = &arglist.args[1];
 871
 872         argv[argc] = NULL;
 873         lastarg = NULL;
 874         if (iflag && funcnest == 0 && argc > 0)
 875                 lastarg = argv[argc - 1];
 876
 877         /* Print the command if xflag is set. */
 878         if (xflag)
 879                 xtracecommand(&varlist, argc, argv);
 880
 881         /* Now locate the command. */
 882         if (argc == 0) {
 883                 /* Variable assignment(s) without command */
 884                 cmdentry.cmdtype = CMDBUILTIN;
 885                 cmdentry.u.index = BLTINCMD;
 886                 cmdentry.special = 0;
 887         } else {
 888                 static const char PATH[] = "PATH=";
 889                 int cmd_flags = 0, bltinonly = 0;
 890
 891                 /*
 892                  * Modify the command lookup path, if a PATH= assignment
 893                  * is present
 894                  */
 895                 for (i = 0; i < varlist.count; i++)
 896                         if (strncmp(varlist.args[i], PATH, sizeof(PATH) - 1) == 0) {
 897                                 path = varlist.args[i] + sizeof(PATH) - 1;
 898                                 /*
 899                                  * On `PATH=... command`, we need to make
 900                                  * sure that the command isn't using the
 901                                  * non-updated hash table of the outer PATH
 902                                  * setting and we need to make sure that
 903                                  * the hash table isn't filled with items
 904                                  * from the temporary setting.
 905                                  *
 906                                  * It would be better to forbit using and
 907                                  * updating the table while this command
 908                                  * runs, by the command finding mechanism
 909                                  * is heavily integrated with hash handling,
 910                                  * so we just delete the hash before and after
 911                                  * the command runs. Partly deleting like
 912                                  * changepatch() does doesn't seem worth the
 913                                  * bookinging effort, since most such runs add
 914                                  * directories in front of the new PATH.
 915                                  */
 916                                 clearcmdentry();
 917                                 do_clearcmdentry = 1;
 918                         }
 919
 920                 for (;;) {
 921                         if (bltinonly) {
 922                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 923                                 if (cmdentry.u.index < 0) {
 924                                         cmdentry.u.index = BLTINCMD;
 925                                         argv--;
 926                                         argc++;
 927                                         break;
 928                                 }
 929                         } else
 930                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 931                         /* implement the bltin and command builtins here */
 932                         if (cmdentry.cmdtype != CMDBUILTIN)
 933                                 break;
 934                         if (cmdentry.u.index == BLTINCMD) {
 935                                 if (argc == 1)
 936                                         break;
 937                                 argv++;
 938                                 argc--;
 939                                 bltinonly = 1;
 940                         } else if (cmdentry.u.index == COMMANDCMD) {
 941                                 if (argc == 1)
 942                                         break;
 943                                 if (!strcmp(argv[1], "-p")) {
 944                                         if (argc == 2)
 945                                                 break;
 946                                         if (argv[2][0] == '-') {
 947                                                 if (strcmp(argv[2], "--"))
 948                                                         break;
 949                                                 if (argc == 3)
 950                                                         break;
 951                                                 argv += 3;
 952                                                 argc -= 3;
 953                                         } else {
 954                                                 argv += 2;
 955                                                 argc -= 2;
 956                                         }
 957                                         path = _PATH_STDPATH;
 958                                         clearcmdentry();
 959                                         do_clearcmdentry = 1;
 960                                 } else if (!strcmp(argv[1], "--")) {
 961                                         if (argc == 2)
 962                                                 break;
 963                                         argv += 2;
 964                                         argc -= 2;
 965                                 } else if (argv[1][0] == '-')
 966                                         break;
 967                                 else {
 968                                         argv++;
 969                                         argc--;
 970                                 }
 971                                 cmd_flags |= DO_NOFUNC;
 972                                 bltinonly = 0;
 973                         } else
 974                                 break;
 975                 }
 976                 /*
 977                  * Special builtins lose their special properties when
 978                  * called via 'command'.
 979                  */
 980                 if (cmd_flags & DO_NOFUNC)
 981                         cmdentry.special = 0;
 982         }
 983
 984         /* Fork off a child process if necessary. */
 985         if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 986             && ((flags & EV_EXIT) == 0 || have_traps()))
 987          || ((flags & EV_BACKCMD) != 0
 988             && (cmdentry.cmdtype != CMDBUILTIN ||
 989                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 990                 jp = makejob(cmd, 1);
 991                 mode = FORK_FG;
 992                 if (flags & EV_BACKCMD) {
 993                         mode = FORK_NOJOB;
 994                         if (pipe(pip) < 0)
 995                                 error("Pipe call failed: %s", strerror(errno));
 996                 }
 997                 if (cmdentry.cmdtype == CMDNORMAL &&
 998                     cmd->ncmd.redirect == NULL &&
 999                     varlist.count == 0 &&
1000                     (mode == FORK_FG || mode == FORK_NOJOB) &&
1001                     !disvforkset() && !iflag && !mflag) {
1002                         vforkexecshell(jp, argv, environment(), path,
1003                             cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL);
1004                         goto parent;
1005                 }
1006                 if (forkshell(jp, cmd, mode) != 0)
1007                         goto parent;    /* at end of routine */
1008                 if (flags & EV_BACKCMD) {
1009                         FORCEINTON;
1010                         close(pip[0]);
1011                         if (pip[1] != 1) {
1012                                 dup2(pip[1], 1);
1013                                 close(pip[1]);
1014                         }
1015                         flags &= ~EV_BACKCMD;
1016                 }
1017                 flags |= EV_EXIT;
1018         }
1019
1020         /* This is the child process if a fork occurred. */
1021         /* Execute the command. */
1022         if (cmdentry.cmdtype == CMDFUNCTION) {
1023 #ifdef DEBUG
1024                 trputs("Shell function:  ");  trargs(argv);
1025 #endif
1026                 saveparam = shellparam;
1027                 shellparam.malloc = 0;
1028                 shellparam.reset = 1;
1029                 shellparam.nparam = argc - 1;
1030                 shellparam.p = argv + 1;
1031                 shellparam.optp = NULL;
1032                 shellparam.optnext = NULL;
1033                 INTOFF;
1034                 savelocalvars = localvars;
1035                 localvars = NULL;
1036                 reffunc(cmdentry.u.func);
1037                 savehandler = handler;
1038                 if (setjmp(jmploc.loc)) {
1039                         popredir();
1040                         unreffunc(cmdentry.u.func);
1041                         poplocalvars();
1042                         localvars = savelocalvars;
1043                         freeparam(&shellparam);
1044                         shellparam = saveparam;
1045                         funcnest--;
1046                         handler = savehandler;
1047                         longjmp(handler->loc, 1);
1048                 }
1049                 handler = &jmploc;
1050                 funcnest++;
1051                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
1052                 INTON;
1053                 for (i = 0; i < varlist.count; i++)
1054                         mklocal(varlist.args[i]);
1055                 exitstatus = oexitstatus;
1056                 evaltree(getfuncnode(cmdentry.u.func),
1057                     flags & (EV_TESTED | EV_EXIT));
1058                 INTOFF;
1059                 unreffunc(cmdentry.u.func);
1060                 poplocalvars();
1061                 localvars = savelocalvars;
1062                 freeparam(&shellparam);
1063                 shellparam = saveparam;
1064                 handler = savehandler;
1065                 funcnest--;
1066                 popredir();
1067                 INTON;
1068                 if (evalskip == SKIPRETURN) {
1069                         evalskip = 0;
1070                         skipcount = 0;
1071                 }
1072                 if (jp)
1073                         exitshell(exitstatus);
1074         } else if (cmdentry.cmdtype == CMDBUILTIN) {
1075 #ifdef DEBUG
1076                 trputs("builtin command:  ");  trargs(argv);
1077 #endif
1078                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
1079                 if (flags == EV_BACKCMD) {
1080                         memout.nextc = memout.buf;
1081                         mode |= REDIR_BACKQ;
1082                 }
1083                 savecmdname = commandname;
1084                 savetopfile = getcurrentfile();
1085                 cmdenviron = &varlist;
1086                 e = -1;
1087                 savehandler = handler;
1088                 if (setjmp(jmploc.loc)) {
1089                         e = exception;
1090                         if (e == EXINT)
1091                                 exitstatus = SIGINT+128;
1092                         else if (e != EXEXIT)
1093                                 exitstatus = 2;
1094                         goto cmddone;
1095                 }
1096                 handler = &jmploc;
1097                 redirect(cmd->ncmd.redirect, mode);
1098                 outclearerror(out1);
1099                 /*
1100                  * If there is no command word, redirection errors should
1101                  * not be fatal but assignment errors should.
1102                  */
1103                 if (argc == 0)
1104                         cmdentry.special = 1;
1105                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1106                 if (argc > 0)
1107                         bltinsetlocale();
1108                 commandname = argv[0];
1109                 argptr = argv + 1;
1110                 nextopt_optptr = NULL;          /* initialize nextopt */
1111                 builtin_flags = flags;
1112                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1113                 flushall();
1114                 if (outiserror(out1)) {
1115                         warning("write error on stdout");
1116                         if (exitstatus == 0 || exitstatus == 1)
1117                                 exitstatus = 2;
1118                 }
1119 cmddone:
1120                 if (argc > 0)
1121                         bltinunsetlocale();
1122                 cmdenviron = NULL;
1123                 out1 = &output;
1124                 out2 = &errout;
1125                 freestdout();
1126                 handler = savehandler;
1127                 commandname = savecmdname;
1128                 if (jp)
1129                         exitshell(exitstatus);
1130                 if (flags == EV_BACKCMD) {
1131                         backcmd->buf = memout.buf;
1132                         backcmd->nleft = memout.buf != NULL ?
1133                             memout.nextc - memout.buf : 0;
1134                         memout.buf = NULL;
1135                         memout.nextc = NULL;
1136                         memout.bufend = NULL;
1137                         memout.bufsize = 64;
1138                 }
1139                 if (cmdentry.u.index != EXECCMD)
1140                         popredir();
1141                 if (e != -1) {
1142                         if ((e != EXERROR && e != EXEXEC)
1143                             || cmdentry.special)
1144                                 exraise(e);
1145                         popfilesupto(savetopfile);
1146                         if (flags != EV_BACKCMD)
1147                                 FORCEINTON;
1148                 }
1149         } else {
1150 #ifdef DEBUG
1151                 trputs("normal command:  ");  trargs(argv);
1152 #endif
1153                 redirect(cmd->ncmd.redirect, 0);
1154                 for (i = 0; i < varlist.count; i++)
1155                         setvareq(varlist.args[i], VEXPORT|VSTACK);
1156                 envp = environment();
1157                 shellexec(argv, envp, path, cmdentry.u.index);
1158                 /*NOTREACHED*/
1159         }
1160         goto out;
1161
1162 parent: /* parent process gets here (if we forked) */
1163         if (mode == FORK_FG) {  /* argument to fork */
1164                 INTOFF;
1165                 exitstatus = waitforjob(jp, &signaled);
1166                 INTON;
1167                 if (iflag && loopnest > 0 && signaled) {
1168                         evalskip = SKIPBREAK;
1169                         skipcount = loopnest;
1170                 }
1171         } else if (mode == FORK_NOJOB) {
1172                 backcmd->fd = pip[0];
1173                 close(pip[1]);
1174                 backcmd->jp = jp;
1175         }
1176
1177 out:
1178         if (lastarg)
1179                 setvar("_", lastarg, 0);
1180         if (do_clearcmdentry)
1181                 clearcmdentry();
1182 }
1183
1184
1185
1186 /*
1187  * Search for a command.  This is called before we fork so that the
1188  * location of the command will be available in the parent as well as
1189  * the child.  The check for "goodname" is an overly conservative
1190  * check that the name will not be subject to expansion.
1191  */
1192
1193 static void
1194 prehash(union node *n)
1195 {
1196         struct cmdentry entry;
1197
1198         if (n && n->type == NCMD && n->ncmd.args)
1199                 if (goodname(n->ncmd.args->narg.text))
1200                         find_command(n->ncmd.args->narg.text, &entry, 0,
1201                                      pathval());
1202 }
1203
1204
1205
1206 /*
1207  * Builtin commands.  Builtin commands whose functions are closely
1208  * tied to evaluation are implemented here.
1209  */
1210
1211 /*
1212  * No command given, a bltin command with no arguments, or a bltin command
1213  * with an invalid name.
1214  */
1215
1216 int
1217 bltincmd(int argc, char **argv)
1218 {
1219         if (argc > 1) {
1220                 out2fmt_flush("%s: not found\n", argv[1]);
1221                 return 127;
1222         }
1223         /*
1224          * Preserve exitstatus of a previous possible command substitution
1225          * as POSIX mandates
1226          */
1227         return exitstatus;
1228 }
1229
1230
1231 /*
1232  * Handle break and continue commands.  Break, continue, and return are
1233  * all handled by setting the evalskip flag.  The evaluation routines
1234  * above all check this flag, and if it is set they start skipping
1235  * commands rather than executing them.  The variable skipcount is
1236  * the number of loops to break/continue, or the number of function
1237  * levels to return.  (The latter is always 1.)  It should probably
1238  * be an error to break out of more loops than exist, but it isn't
1239  * in the standard shell so we don't make it one here.
1240  */
1241
1242 int
1243 breakcmd(int argc, char **argv)
1244 {
1245         long n;
1246         char *end;
1247
1248         if (argc > 1) {
1249                 /* Allow arbitrarily large numbers. */
1250                 n = strtol(argv[1], &end, 10);
1251                 if (!is_digit(argv[1][0]) || *end != '\0')
1252                         error("Illegal number: %s", argv[1]);
1253         } else
1254                 n = 1;
1255         if (n > loopnest)
1256                 n = loopnest;
1257         if (n > 0) {
1258                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1259                 skipcount = n;
1260         }
1261         return 0;
1262 }
1263
1264 /*
1265  * The `command' command.
1266  */
1267 int
1268 commandcmd(int argc __unused, char **argv __unused)
1269 {
1270         const char *path;
1271         int ch;
1272         int cmd = -1;
1273
1274         path = bltinlookup("PATH", 1);
1275
1276         while ((ch = nextopt("pvV")) != '\0') {
1277                 switch (ch) {
1278                 case 'p':
1279                         path = _PATH_STDPATH;
1280                         break;
1281                 case 'v':
1282                         cmd = TYPECMD_SMALLV;
1283                         break;
1284                 case 'V':
1285                         cmd = TYPECMD_BIGV;
1286                         break;
1287                 }
1288         }
1289
1290         if (cmd != -1) {
1291                 if (*argptr == NULL || argptr[1] != NULL)
1292                         error("wrong number of arguments");
1293                 return typecmd_impl(2, argptr - 1, cmd, path);
1294         }
1295         if (*argptr != NULL)
1296                 error("commandcmd bad call");
1297
1298         /*
1299          * Do nothing successfully if no command was specified;
1300          * ksh also does this.
1301          */
1302         return 0;
1303 }
1304
1305
1306 /*
1307  * The return command.
1308  */
1309
1310 int
1311 returncmd(int argc, char **argv)
1312 {
1313         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1314
1315         evalskip = SKIPRETURN;
1316         skipcount = 1;
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         int i;
1339
1340         /*
1341          * Because we have historically not supported any options,
1342          * only treat "--" specially.
1343          */
1344         if (argc > 1 && strcmp(argv[1], "--") == 0)
1345                 argc--, argv++;
1346         if (argc > 1) {
1347                 iflag = 0;              /* exit on error */
1348                 mflag = 0;
1349                 optschanged();
1350                 for (i = 0; i < cmdenviron->count; i++)
1351                         setvareq(cmdenviron->args[i], 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 }