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                                 if (e == EXERROR)
 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)
 674                                 exitstatus = 2;
 675                         else if (exception == EXEXEC)
 676                                 /* nothing */;
 677                         else if (exception != 0) {
 678                                 handler = savehandler;
 679                                 forcelocal--;
 680                                 poplocalvars();
 681                                 localvars = savelocalvars;
 682                                 shellparam.reset = saveoptreset;
 683                                 longjmp(handler->loc, 1);
 684                         }
 685                 } else {
 686                         handler = &jmploc;
 687                         evalcommand(n, EV_BACKCMD, result);
 688                 }
 689                 handler = savehandler;
 690                 forcelocal--;
 691                 poplocalvars();
 692                 localvars = savelocalvars;
 693                 shellparam.reset = saveoptreset;
 694         } else {
 695                 if (pipe(pip) < 0)
 696                         error("Pipe call failed: %s", strerror(errno));
 697                 jp = makejob(n, 1);
 698                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 699                         FORCEINTON;
 700                         close(pip[0]);
 701                         if (pip[1] != 1) {
 702                                 dup2(pip[1], 1);
 703                                 close(pip[1]);
 704                         }
 705                         evaltree(n, EV_EXIT);
 706                 }
 707                 close(pip[1]);
 708                 result->fd = pip[0];
 709                 result->jp = jp;
 710         }
 711         popstackmark(&smark);
 712         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 713                 result->fd, result->buf, result->nleft, result->jp));
 714 }
 715
 716 static int
 717 mustexpandto(const char *argtext, const char *mask)
 718 {
 719         for (;;) {
 720                 if (*argtext == CTLQUOTEMARK || *argtext == CTLQUOTEEND) {
 721                         argtext++;
 722                         continue;
 723                 }
 724                 if (*argtext == CTLESC)
 725                         argtext++;
 726                 else if (BASESYNTAX[(int)*argtext] == CCTL)
 727                         return (0);
 728                 if (*argtext != *mask)
 729                         return (0);
 730                 if (*argtext == '\0')
 731                         return (1);
 732                 argtext++;
 733                 mask++;
 734         }
 735 }
 736
 737 static int
 738 isdeclarationcmd(struct narg *arg)
 739 {
 740         int have_command = 0;
 741
 742         if (arg == NULL)
 743                 return (0);
 744         while (mustexpandto(arg->text, "command")) {
 745                 have_command = 1;
 746                 arg = &arg->next->narg;
 747                 if (arg == NULL)
 748                         return (0);
 749                 /*
 750                  * To also allow "command -p" and "command --" as part of
 751                  * a declaration command, add code here.
 752                  * We do not do this, as ksh does not do it either and it
 753                  * is not required by POSIX.
 754                  */
 755         }
 756         return (mustexpandto(arg->text, "export") ||
 757             mustexpandto(arg->text, "readonly") ||
 758             (mustexpandto(arg->text, "local") &&
 759                 (have_command || !isfunc("local"))));
 760 }
 761
 762 static void
 763 xtracecommand(struct arglist *varlist, int argc, char **argv)
 764 {
 765         char sep = 0;
 766         const char *text, *p, *ps4;
 767         int i;
 768
 769         ps4 = expandstr(ps4val());
 770         out2str(ps4 != NULL ? ps4 : ps4val());
 771         for (i = 0; i < varlist->count; i++) {
 772                 text = varlist->args[i];
 773                 if (sep != 0)
 774                         out2c(' ');
 775                 p = strchr(text, '=');
 776                 if (p != NULL) {
 777                         p++;
 778                         outbin(text, p - text, out2);
 779                         out2qstr(p);
 780                 } else
 781                         out2qstr(text);
 782                 sep = ' ';
 783         }
 784         for (i = 0; i < argc; i++) {
 785                 text = argv[i];
 786                 if (sep != 0)
 787                         out2c(' ');
 788                 out2qstr(text);
 789                 sep = ' ';
 790         }
 791         out2c('\n');
 792         flushout(&errout);
 793 }
 794
 795 /*
 796  * Check if a builtin can safely be executed in the same process,
 797  * even though it should be in a subshell (command substitution).
 798  * Note that jobid, jobs, times and trap can show information not
 799  * available in a child process; this is deliberate.
 800  * The arguments should already have been expanded.
 801  */
 802 static int
 803 safe_builtin(int idx, int argc, char **argv)
 804 {
 805         /* Generated from builtins.def. */
 806         if (safe_builtin_always(idx))
 807                 return (1);
 808         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 809             idx == UMASKCMD)
 810                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 811         if (idx == SETCMD)
 812                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 813                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 814                     argv[1][2] == '\0'));
 815         return (0);
 816 }
 817
 818 /*
 819  * Execute a simple command.
 820  * Note: This may or may not return if (flags & EV_EXIT).
 821  */
 822
 823 static void
 824 evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
 825 {
 826         union node *argp;
 827         struct arglist arglist;
 828         struct arglist varlist;
 829         char **argv;
 830         int argc;
 831         char **envp;
 832         int varflag;
 833         int mode;
 834         int pip[2];
 835         struct cmdentry cmdentry;
 836         struct job *jp;
 837         struct jmploc jmploc;
 838         struct jmploc *savehandler;
 839         char *savecmdname;
 840         struct shparam saveparam;
 841         struct localvar *savelocalvars;
 842         struct parsefile *savetopfile;
 843         volatile int e;
 844         char *lastarg;
 845         int signaled;
 846         int do_clearcmdentry;
 847         const char *path = pathval();
 848         int i;
 849
 850         /* First expand the arguments. */
 851         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 852         emptyarglist(&arglist);
 853         emptyarglist(&varlist);
 854         varflag = 1;
 855         jp = NULL;
 856         do_clearcmdentry = 0;
 857         oexitstatus = exitstatus;
 858         exitstatus = 0;
 859         /* Add one slot at the beginning for tryexec(). */
 860         appendarglist(&arglist, nullstr);
 861         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 862                 if (varflag && isassignment(argp->narg.text)) {
 863                         expandarg(argp, varflag == 1 ? &varlist : &arglist,
 864                             EXP_VARTILDE);
 865                         continue;
 866                 } else if (varflag == 1)
 867                         varflag = isdeclarationcmd(&argp->narg) ? 2 : 0;
 868                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 869         }
 870         appendarglist(&arglist, nullstr);
 871         expredir(cmd->ncmd.redirect);
 872         argc = arglist.count - 2;
 873         argv = &arglist.args[1];
 874
 875         argv[argc] = NULL;
 876         lastarg = NULL;
 877         if (iflag && funcnest == 0 && argc > 0)
 878                 lastarg = argv[argc - 1];
 879
 880         /* Print the command if xflag is set. */
 881         if (xflag)
 882                 xtracecommand(&varlist, argc, argv);
 883
 884         /* Now locate the command. */
 885         if (argc == 0) {
 886                 /* Variable assignment(s) without command */
 887                 cmdentry.cmdtype = CMDBUILTIN;
 888                 cmdentry.u.index = BLTINCMD;
 889                 cmdentry.special = 0;
 890         } else {
 891                 static const char PATH[] = "PATH=";
 892                 int cmd_flags = 0, bltinonly = 0;
 893
 894                 /*
 895                  * Modify the command lookup path, if a PATH= assignment
 896                  * is present
 897                  */
 898                 for (i = 0; i < varlist.count; i++)
 899                         if (strncmp(varlist.args[i], PATH, sizeof(PATH) - 1) == 0) {
 900                                 path = varlist.args[i] + sizeof(PATH) - 1;
 901                                 /*
 902                                  * On `PATH=... command`, we need to make
 903                                  * sure that the command isn't using the
 904                                  * non-updated hash table of the outer PATH
 905                                  * setting and we need to make sure that
 906                                  * the hash table isn't filled with items
 907                                  * from the temporary setting.
 908                                  *
 909                                  * It would be better to forbit using and
 910                                  * updating the table while this command
 911                                  * runs, by the command finding mechanism
 912                                  * is heavily integrated with hash handling,
 913                                  * so we just delete the hash before and after
 914                                  * the command runs. Partly deleting like
 915                                  * changepatch() does doesn't seem worth the
 916                                  * bookinging effort, since most such runs add
 917                                  * directories in front of the new PATH.
 918                                  */
 919                                 clearcmdentry();
 920                                 do_clearcmdentry = 1;
 921                         }
 922
 923                 for (;;) {
 924                         if (bltinonly) {
 925                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 926                                 if (cmdentry.u.index < 0) {
 927                                         cmdentry.u.index = BLTINCMD;
 928                                         argv--;
 929                                         argc++;
 930                                         break;
 931                                 }
 932                         } else
 933                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 934                         /* implement the bltin and command builtins here */
 935                         if (cmdentry.cmdtype != CMDBUILTIN)
 936                                 break;
 937                         if (cmdentry.u.index == BLTINCMD) {
 938                                 if (argc == 1)
 939                                         break;
 940                                 argv++;
 941                                 argc--;
 942                                 bltinonly = 1;
 943                         } else if (cmdentry.u.index == COMMANDCMD) {
 944                                 if (argc == 1)
 945                                         break;
 946                                 if (!strcmp(argv[1], "-p")) {
 947                                         if (argc == 2)
 948                                                 break;
 949                                         if (argv[2][0] == '-') {
 950                                                 if (strcmp(argv[2], "--"))
 951                                                         break;
 952                                                 if (argc == 3)
 953                                                         break;
 954                                                 argv += 3;
 955                                                 argc -= 3;
 956                                         } else {
 957                                                 argv += 2;
 958                                                 argc -= 2;
 959                                         }
 960                                         path = _PATH_STDPATH;
 961                                         clearcmdentry();
 962                                         do_clearcmdentry = 1;
 963                                 } else if (!strcmp(argv[1], "--")) {
 964                                         if (argc == 2)
 965                                                 break;
 966                                         argv += 2;
 967                                         argc -= 2;
 968                                 } else if (argv[1][0] == '-')
 969                                         break;
 970                                 else {
 971                                         argv++;
 972                                         argc--;
 973                                 }
 974                                 cmd_flags |= DO_NOFUNC;
 975                                 bltinonly = 0;
 976                         } else
 977                                 break;
 978                 }
 979                 /*
 980                  * Special builtins lose their special properties when
 981                  * called via 'command'.
 982                  */
 983                 if (cmd_flags & DO_NOFUNC)
 984                         cmdentry.special = 0;
 985         }
 986
 987         /* Fork off a child process if necessary. */
 988         if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 989             && ((flags & EV_EXIT) == 0 || have_traps()))
 990          || ((flags & EV_BACKCMD) != 0
 991             && (cmdentry.cmdtype != CMDBUILTIN ||
 992                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 993                 jp = makejob(cmd, 1);
 994                 mode = FORK_FG;
 995                 if (flags & EV_BACKCMD) {
 996                         mode = FORK_NOJOB;
 997                         if (pipe(pip) < 0)
 998                                 error("Pipe call failed: %s", strerror(errno));
 999                 }
1000                 if (cmdentry.cmdtype == CMDNORMAL &&
1001                     cmd->ncmd.redirect == NULL &&
1002                     varlist.count == 0 &&
1003                     (mode == FORK_FG || mode == FORK_NOJOB) &&
1004                     !disvforkset() && !iflag && !mflag) {
1005                         vforkexecshell(jp, argv, environment(), path,
1006                             cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL);
1007                         goto parent;
1008                 }
1009                 if (forkshell(jp, cmd, mode) != 0)
1010                         goto parent;    /* at end of routine */
1011                 if (flags & EV_BACKCMD) {
1012                         FORCEINTON;
1013                         close(pip[0]);
1014                         if (pip[1] != 1) {
1015                                 dup2(pip[1], 1);
1016                                 close(pip[1]);
1017                         }
1018                         flags &= ~EV_BACKCMD;
1019                 }
1020                 flags |= EV_EXIT;
1021         }
1022
1023         /* This is the child process if a fork occurred. */
1024         /* Execute the command. */
1025         if (cmdentry.cmdtype == CMDFUNCTION) {
1026 #ifdef DEBUG
1027                 trputs("Shell function:  ");  trargs(argv);
1028 #endif
1029                 saveparam = shellparam;
1030                 shellparam.malloc = 0;
1031                 shellparam.reset = 1;
1032                 shellparam.nparam = argc - 1;
1033                 shellparam.p = argv + 1;
1034                 shellparam.optp = NULL;
1035                 shellparam.optnext = NULL;
1036                 INTOFF;
1037                 savelocalvars = localvars;
1038                 localvars = NULL;
1039                 reffunc(cmdentry.u.func);
1040                 savehandler = handler;
1041                 if (setjmp(jmploc.loc)) {
1042                         popredir();
1043                         unreffunc(cmdentry.u.func);
1044                         poplocalvars();
1045                         localvars = savelocalvars;
1046                         freeparam(&shellparam);
1047                         shellparam = saveparam;
1048                         funcnest--;
1049                         handler = savehandler;
1050                         longjmp(handler->loc, 1);
1051                 }
1052                 handler = &jmploc;
1053                 funcnest++;
1054                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
1055                 INTON;
1056                 for (i = 0; i < varlist.count; i++)
1057                         mklocal(varlist.args[i]);
1058                 exitstatus = oexitstatus;
1059                 evaltree(getfuncnode(cmdentry.u.func),
1060                     flags & (EV_TESTED | EV_EXIT));
1061                 INTOFF;
1062                 unreffunc(cmdentry.u.func);
1063                 poplocalvars();
1064                 localvars = savelocalvars;
1065                 freeparam(&shellparam);
1066                 shellparam = saveparam;
1067                 handler = savehandler;
1068                 funcnest--;
1069                 popredir();
1070                 INTON;
1071                 if (evalskip == SKIPRETURN) {
1072                         evalskip = 0;
1073                         skipcount = 0;
1074                 }
1075                 if (jp)
1076                         exitshell(exitstatus);
1077         } else if (cmdentry.cmdtype == CMDBUILTIN) {
1078 #ifdef DEBUG
1079                 trputs("builtin command:  ");  trargs(argv);
1080 #endif
1081                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
1082                 if (flags == EV_BACKCMD) {
1083                         memout.nextc = memout.buf;
1084                         mode |= REDIR_BACKQ;
1085                 }
1086                 savecmdname = commandname;
1087                 savetopfile = getcurrentfile();
1088                 cmdenviron = &varlist;
1089                 e = -1;
1090                 savehandler = handler;
1091                 if (setjmp(jmploc.loc)) {
1092                         e = exception;
1093                         if (e == EXINT)
1094                                 exitstatus = SIGINT+128;
1095                         else if (e != EXEXEC && e != EXEXIT)
1096                                 exitstatus = 2;
1097                         goto cmddone;
1098                 }
1099                 handler = &jmploc;
1100                 redirect(cmd->ncmd.redirect, mode);
1101                 outclearerror(out1);
1102                 /*
1103                  * If there is no command word, redirection errors should
1104                  * not be fatal but assignment errors should.
1105                  */
1106                 if (argc == 0)
1107                         cmdentry.special = 1;
1108                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1109                 if (argc > 0)
1110                         bltinsetlocale();
1111                 commandname = argv[0];
1112                 argptr = argv + 1;
1113                 nextopt_optptr = NULL;          /* initialize nextopt */
1114                 builtin_flags = flags;
1115                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1116                 flushall();
1117                 if (outiserror(out1)) {
1118                         warning("write error on stdout");
1119                         if (exitstatus == 0 || exitstatus == 1)
1120                                 exitstatus = 2;
1121                 }
1122 cmddone:
1123                 if (argc > 0)
1124                         bltinunsetlocale();
1125                 cmdenviron = NULL;
1126                 out1 = &output;
1127                 out2 = &errout;
1128                 freestdout();
1129                 handler = savehandler;
1130                 commandname = savecmdname;
1131                 if (jp)
1132                         exitshell(exitstatus);
1133                 if (flags == EV_BACKCMD) {
1134                         backcmd->buf = memout.buf;
1135                         backcmd->nleft = memout.buf != NULL ?
1136                             memout.nextc - memout.buf : 0;
1137                         memout.buf = NULL;
1138                         memout.nextc = NULL;
1139                         memout.bufend = NULL;
1140                         memout.bufsize = 64;
1141                 }
1142                 if (cmdentry.u.index != EXECCMD)
1143                         popredir();
1144                 if (e != -1) {
1145                         if ((e != EXERROR && e != EXEXEC)
1146                             || cmdentry.special)
1147                                 exraise(e);
1148                         popfilesupto(savetopfile);
1149                         if (flags != EV_BACKCMD)
1150                                 FORCEINTON;
1151                 }
1152         } else {
1153 #ifdef DEBUG
1154                 trputs("normal command:  ");  trargs(argv);
1155 #endif
1156                 redirect(cmd->ncmd.redirect, 0);
1157                 for (i = 0; i < varlist.count; i++)
1158                         setvareq(varlist.args[i], VEXPORT|VSTACK);
1159                 envp = environment();
1160                 shellexec(argv, envp, path, cmdentry.u.index);
1161                 /*NOTREACHED*/
1162         }
1163         goto out;
1164
1165 parent: /* parent process gets here (if we forked) */
1166         if (mode == FORK_FG) {  /* argument to fork */
1167                 INTOFF;
1168                 exitstatus = waitforjob(jp, &signaled);
1169                 INTON;
1170                 if (iflag && loopnest > 0 && signaled) {
1171                         evalskip = SKIPBREAK;
1172                         skipcount = loopnest;
1173                 }
1174         } else if (mode == FORK_NOJOB) {
1175                 backcmd->fd = pip[0];
1176                 close(pip[1]);
1177                 backcmd->jp = jp;
1178         }
1179
1180 out:
1181         if (lastarg)
1182                 setvar("_", lastarg, 0);
1183         if (do_clearcmdentry)
1184                 clearcmdentry();
1185 }
1186
1187
1188
1189 /*
1190  * Search for a command.  This is called before we fork so that the
1191  * location of the command will be available in the parent as well as
1192  * the child.  The check for "goodname" is an overly conservative
1193  * check that the name will not be subject to expansion.
1194  */
1195
1196 static void
1197 prehash(union node *n)
1198 {
1199         struct cmdentry entry;
1200
1201         if (n && n->type == NCMD && n->ncmd.args)
1202                 if (goodname(n->ncmd.args->narg.text))
1203                         find_command(n->ncmd.args->narg.text, &entry, 0,
1204                                      pathval());
1205 }
1206
1207
1208
1209 /*
1210  * Builtin commands.  Builtin commands whose functions are closely
1211  * tied to evaluation are implemented here.
1212  */
1213
1214 /*
1215  * No command given, a bltin command with no arguments, or a bltin command
1216  * with an invalid name.
1217  */
1218
1219 int
1220 bltincmd(int argc, char **argv)
1221 {
1222         if (argc > 1) {
1223                 out2fmt_flush("%s: not found\n", argv[1]);
1224                 return 127;
1225         }
1226         /*
1227          * Preserve exitstatus of a previous possible command substitution
1228          * as POSIX mandates
1229          */
1230         return exitstatus;
1231 }
1232
1233
1234 /*
1235  * Handle break and continue commands.  Break, continue, and return are
1236  * all handled by setting the evalskip flag.  The evaluation routines
1237  * above all check this flag, and if it is set they start skipping
1238  * commands rather than executing them.  The variable skipcount is
1239  * the number of loops to break/continue, or the number of function
1240  * levels to return.  (The latter is always 1.)  It should probably
1241  * be an error to break out of more loops than exist, but it isn't
1242  * in the standard shell so we don't make it one here.
1243  */
1244
1245 int
1246 breakcmd(int argc, char **argv)
1247 {
1248         long n;
1249         char *end;
1250
1251         if (argc > 1) {
1252                 /* Allow arbitrarily large numbers. */
1253                 n = strtol(argv[1], &end, 10);
1254                 if (!is_digit(argv[1][0]) || *end != '\0')
1255                         error("Illegal number: %s", argv[1]);
1256         } else
1257                 n = 1;
1258         if (n > loopnest)
1259                 n = loopnest;
1260         if (n > 0) {
1261                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1262                 skipcount = n;
1263         }
1264         return 0;
1265 }
1266
1267 /*
1268  * The `command' command.
1269  */
1270 int
1271 commandcmd(int argc __unused, char **argv __unused)
1272 {
1273         const char *path;
1274         int ch;
1275         int cmd = -1;
1276
1277         path = bltinlookup("PATH", 1);
1278
1279         while ((ch = nextopt("pvV")) != '\0') {
1280                 switch (ch) {
1281                 case 'p':
1282                         path = _PATH_STDPATH;
1283                         break;
1284                 case 'v':
1285                         cmd = TYPECMD_SMALLV;
1286                         break;
1287                 case 'V':
1288                         cmd = TYPECMD_BIGV;
1289                         break;
1290                 }
1291         }
1292
1293         if (cmd != -1) {
1294                 if (*argptr == NULL || argptr[1] != NULL)
1295                         error("wrong number of arguments");
1296                 return typecmd_impl(2, argptr - 1, cmd, path);
1297         }
1298         if (*argptr != NULL)
1299                 error("commandcmd bad call");
1300
1301         /*
1302          * Do nothing successfully if no command was specified;
1303          * ksh also does this.
1304          */
1305         return 0;
1306 }
1307
1308
1309 /*
1310  * The return command.
1311  */
1312
1313 int
1314 returncmd(int argc, char **argv)
1315 {
1316         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1317
1318         evalskip = SKIPRETURN;
1319         skipcount = 1;
1320         return ret;
1321 }
1322
1323
1324 int
1325 falsecmd(int argc __unused, char **argv __unused)
1326 {
1327         return 1;
1328 }
1329
1330
1331 int
1332 truecmd(int argc __unused, char **argv __unused)
1333 {
1334         return 0;
1335 }
1336
1337
1338 int
1339 execcmd(int argc, char **argv)
1340 {
1341         int i;
1342
1343         /*
1344          * Because we have historically not supported any options,
1345          * only treat "--" specially.
1346          */
1347         if (argc > 1 && strcmp(argv[1], "--") == 0)
1348                 argc--, argv++;
1349         if (argc > 1) {
1350                 iflag = 0;              /* exit on error */
1351                 mflag = 0;
1352                 optschanged();
1353                 for (i = 0; i < cmdenviron->count; i++)
1354                         setvareq(cmdenviron->args[i], VEXPORT|VSTACK);
1355                 shellexec(argv + 1, environment(), pathval(), 0);
1356
1357         }
1358         return 0;
1359 }
1360
1361
1362 int
1363 timescmd(int argc __unused, char **argv __unused)
1364 {
1365         struct rusage ru;
1366         long shumins, shsmins, chumins, chsmins;
1367         double shusecs, shssecs, chusecs, chssecs;
1368
1369         if (getrusage(RUSAGE_SELF, &ru) < 0)
1370                 return 1;
1371         shumins = ru.ru_utime.tv_sec / 60;
1372         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1373         shsmins = ru.ru_stime.tv_sec / 60;
1374         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1375         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1376                 return 1;
1377         chumins = ru.ru_utime.tv_sec / 60;
1378         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1379         chsmins = ru.ru_stime.tv_sec / 60;
1380         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1381         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1382             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1383         return 0;
1384 }