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