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