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: head/bin/sh/eval.c 340284 2018-11-09 14:58:24Z jilles $");
  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 && in_redirect) {
 470                         FORCEINTON;
 471                         return;
 472                 }
 473                 longjmp(handler->loc, 1);
 474         } else {
 475                 INTOFF;
 476                 handler = &jmploc;
 477                 redirect(n->nredir.redirect, REDIR_PUSH);
 478                 in_redirect = 0;
 479                 INTON;
 480                 evaltree(n->nredir.n, flags);
 481         }
 482         INTOFF;
 483         handler = savehandler;
 484         popredir();
 485         INTON;
 486 }
 487
 488
 489 static void
 490 exphere(union node *redir, struct arglist *fn)
 491 {
 492         struct jmploc jmploc;
 493         struct jmploc *savehandler;
 494         struct localvar *savelocalvars;
 495         int need_longjmp = 0;
 496         unsigned char saveoptreset;
 497
 498         redir->nhere.expdoc = "";
 499         savelocalvars = localvars;
 500         localvars = NULL;
 501         saveoptreset = shellparam.reset;
 502         forcelocal++;
 503         savehandler = handler;
 504         if (setjmp(jmploc.loc))
 505                 need_longjmp = exception != EXERROR;
 506         else {
 507                 handler = &jmploc;
 508                 expandarg(redir->nhere.doc, fn, 0);
 509                 redir->nhere.expdoc = fn->args[0];
 510                 INTOFF;
 511         }
 512         handler = savehandler;
 513         forcelocal--;
 514         poplocalvars();
 515         localvars = savelocalvars;
 516         shellparam.reset = saveoptreset;
 517         if (need_longjmp)
 518                 longjmp(handler->loc, 1);
 519         INTON;
 520 }
 521
 522
 523 /*
 524  * Compute the names of the files in a redirection list.
 525  */
 526
 527 static void
 528 expredir(union node *n)
 529 {
 530         union node *redir;
 531
 532         for (redir = n ; redir ; redir = redir->nfile.next) {
 533                 struct arglist fn;
 534                 emptyarglist(&fn);
 535                 switch (redir->type) {
 536                 case NFROM:
 537                 case NTO:
 538                 case NFROMTO:
 539                 case NAPPEND:
 540                 case NCLOBBER:
 541                         expandarg(redir->nfile.fname, &fn, EXP_TILDE);
 542                         redir->nfile.expfname = fn.args[0];
 543                         break;
 544                 case NFROMFD:
 545                 case NTOFD:
 546                         if (redir->ndup.vname) {
 547                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE);
 548                                 fixredir(redir, fn.args[0], 1);
 549                         }
 550                         break;
 551                 case NXHERE:
 552                         exphere(redir, &fn);
 553                         break;
 554                 }
 555         }
 556 }
 557
 558
 559
 560 /*
 561  * Evaluate a pipeline.  All the processes in the pipeline are children
 562  * of the process creating the pipeline.  (This differs from some versions
 563  * of the shell, which make the last process in a pipeline the parent
 564  * of all the rest.)
 565  */
 566
 567 static void
 568 evalpipe(union node *n)
 569 {
 570         struct job *jp;
 571         struct nodelist *lp;
 572         int pipelen;
 573         int prevfd;
 574         int pip[2];
 575
 576         TRACE(("evalpipe(%p) called\n", (void *)n));
 577         pipelen = 0;
 578         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
 579                 pipelen++;
 580         INTOFF;
 581         jp = makejob(n, pipelen);
 582         prevfd = -1;
 583         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
 584                 prehash(lp->n);
 585                 pip[1] = -1;
 586                 if (lp->next) {
 587                         if (pipe(pip) < 0) {
 588                                 if (prevfd >= 0)
 589                                         close(prevfd);
 590                                 error("Pipe call failed: %s", strerror(errno));
 591                         }
 592                 }
 593                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
 594                         INTON;
 595                         if (prevfd > 0) {
 596                                 dup2(prevfd, 0);
 597                                 close(prevfd);
 598                         }
 599                         if (pip[1] >= 0) {
 600                                 if (!(prevfd >= 0 && pip[0] == 0))
 601                                         close(pip[0]);
 602                                 if (pip[1] != 1) {
 603                                         dup2(pip[1], 1);
 604                                         close(pip[1]);
 605                                 }
 606                         }
 607                         evaltree(lp->n, EV_EXIT);
 608                 }
 609                 if (prevfd >= 0)
 610                         close(prevfd);
 611                 prevfd = pip[0];
 612                 if (pip[1] != -1)
 613                         close(pip[1]);
 614         }
 615         INTON;
 616         if (n->npipe.backgnd == 0) {
 617                 INTOFF;
 618                 exitstatus = waitforjob(jp, (int *)NULL);
 619                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 620                 INTON;
 621         } else
 622                 exitstatus = 0;
 623 }
 624
 625
 626
 627 static int
 628 is_valid_fast_cmdsubst(union node *n)
 629 {
 630
 631         return (n->type == NCMD);
 632 }
 633
 634 /*
 635  * Execute a command inside back quotes.  If it's a builtin command, we
 636  * want to save its output in a block obtained from malloc.  Otherwise
 637  * we fork off a subprocess and get the output of the command via a pipe.
 638  * Should be called with interrupts off.
 639  */
 640
 641 void
 642 evalbackcmd(union node *n, struct backcmd *result)
 643 {
 644         int pip[2];
 645         struct job *jp;
 646         struct stackmark smark;
 647         struct jmploc jmploc;
 648         struct jmploc *savehandler;
 649         struct localvar *savelocalvars;
 650         unsigned char saveoptreset;
 651
 652         result->fd = -1;
 653         result->buf = NULL;
 654         result->nleft = 0;
 655         result->jp = NULL;
 656         if (n == NULL) {
 657                 exitstatus = 0;
 658                 return;
 659         }
 660         setstackmark(&smark);
 661         exitstatus = oexitstatus;
 662         if (is_valid_fast_cmdsubst(n)) {
 663                 savelocalvars = localvars;
 664                 localvars = NULL;
 665                 saveoptreset = shellparam.reset;
 666                 forcelocal++;
 667                 savehandler = handler;
 668                 if (setjmp(jmploc.loc)) {
 669                         if (exception == EXERROR)
 670                                 /* nothing */;
 671                         else if (exception != 0) {
 672                                 handler = savehandler;
 673                                 forcelocal--;
 674                                 poplocalvars();
 675                                 localvars = savelocalvars;
 676                                 shellparam.reset = saveoptreset;
 677                                 longjmp(handler->loc, 1);
 678                         }
 679                 } else {
 680                         handler = &jmploc;
 681                         evalcommand(n, EV_BACKCMD, result);
 682                 }
 683                 handler = savehandler;
 684                 forcelocal--;
 685                 poplocalvars();
 686                 localvars = savelocalvars;
 687                 shellparam.reset = saveoptreset;
 688         } else {
 689                 if (pipe(pip) < 0)
 690                         error("Pipe call failed: %s", strerror(errno));
 691                 jp = makejob(n, 1);
 692                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 693                         FORCEINTON;
 694                         close(pip[0]);
 695                         if (pip[1] != 1) {
 696                                 dup2(pip[1], 1);
 697                                 close(pip[1]);
 698                         }
 699                         evaltree(n, EV_EXIT);
 700                 }
 701                 close(pip[1]);
 702                 result->fd = pip[0];
 703                 result->jp = jp;
 704         }
 705         popstackmark(&smark);
 706         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 707                 result->fd, result->buf, result->nleft, result->jp));
 708 }
 709
 710 static int
 711 mustexpandto(const char *argtext, const char *mask)
 712 {
 713         for (;;) {
 714                 if (*argtext == CTLQUOTEMARK || *argtext == CTLQUOTEEND) {
 715                         argtext++;
 716                         continue;
 717                 }
 718                 if (*argtext == CTLESC)
 719                         argtext++;
 720                 else if (BASESYNTAX[(int)*argtext] == CCTL)
 721                         return (0);
 722                 if (*argtext != *mask)
 723                         return (0);
 724                 if (*argtext == '\0')
 725                         return (1);
 726                 argtext++;
 727                 mask++;
 728         }
 729 }
 730
 731 static int
 732 isdeclarationcmd(struct narg *arg)
 733 {
 734         int have_command = 0;
 735
 736         if (arg == NULL)
 737                 return (0);
 738         while (mustexpandto(arg->text, "command")) {
 739                 have_command = 1;
 740                 arg = &arg->next->narg;
 741                 if (arg == NULL)
 742                         return (0);
 743                 /*
 744                  * To also allow "command -p" and "command --" as part of
 745                  * a declaration command, add code here.
 746                  * We do not do this, as ksh does not do it either and it
 747                  * is not required by POSIX.
 748                  */
 749         }
 750         return (mustexpandto(arg->text, "export") ||
 751             mustexpandto(arg->text, "readonly") ||
 752             (mustexpandto(arg->text, "local") &&
 753                 (have_command || !isfunc("local"))));
 754 }
 755
 756 static void
 757 xtracecommand(struct arglist *varlist, int argc, char **argv)
 758 {
 759         char sep = 0;
 760         const char *text, *p, *ps4;
 761         int i;
 762
 763         ps4 = expandstr(ps4val());
 764         out2str(ps4 != NULL ? ps4 : ps4val());
 765         for (i = 0; i < varlist->count; i++) {
 766                 text = varlist->args[i];
 767                 if (sep != 0)
 768                         out2c(' ');
 769                 p = strchr(text, '=');
 770                 if (p != NULL) {
 771                         p++;
 772                         outbin(text, p - text, out2);
 773                         out2qstr(p);
 774                 } else
 775                         out2qstr(text);
 776                 sep = ' ';
 777         }
 778         for (i = 0; i < argc; i++) {
 779                 text = argv[i];
 780                 if (sep != 0)
 781                         out2c(' ');
 782                 out2qstr(text);
 783                 sep = ' ';
 784         }
 785         out2c('\n');
 786         flushout(&errout);
 787 }
 788
 789 /*
 790  * Check if a builtin can safely be executed in the same process,
 791  * even though it should be in a subshell (command substitution).
 792  * Note that jobid, jobs, times and trap can show information not
 793  * available in a child process; this is deliberate.
 794  * The arguments should already have been expanded.
 795  */
 796 static int
 797 safe_builtin(int idx, int argc, char **argv)
 798 {
 799         /* Generated from builtins.def. */
 800         if (safe_builtin_always(idx))
 801                 return (1);
 802         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 803             idx == UMASKCMD)
 804                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 805         if (idx == SETCMD)
 806                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 807                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 808                     argv[1][2] == '\0'));
 809         return (0);
 810 }
 811
 812 /*
 813  * Execute a simple command.
 814  * Note: This may or may not return if (flags & EV_EXIT).
 815  */
 816
 817 static void
 818 evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
 819 {
 820         union node *argp;
 821         struct arglist arglist;
 822         struct arglist varlist;
 823         char **argv;
 824         int argc;
 825         char **envp;
 826         int varflag;
 827         int mode;
 828         int pip[2];
 829         struct cmdentry cmdentry;
 830         struct job *jp;
 831         struct jmploc jmploc;
 832         struct jmploc *savehandler;
 833         char *savecmdname;
 834         struct shparam saveparam;
 835         struct localvar *savelocalvars;
 836         struct parsefile *savetopfile;
 837         volatile int e;
 838         char *lastarg;
 839         int signaled;
 840         int do_clearcmdentry;
 841         const char *path = pathval();
 842         int i;
 843
 844         /* First expand the arguments. */
 845         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 846         emptyarglist(&arglist);
 847         emptyarglist(&varlist);
 848         varflag = 1;
 849         jp = NULL;
 850         do_clearcmdentry = 0;
 851         oexitstatus = exitstatus;
 852         exitstatus = 0;
 853         /* Add one slot at the beginning for tryexec(). */
 854         appendarglist(&arglist, nullstr);
 855         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 856                 if (varflag && isassignment(argp->narg.text)) {
 857                         expandarg(argp, varflag == 1 ? &varlist : &arglist,
 858                             EXP_VARTILDE);
 859                         continue;
 860                 } else if (varflag == 1)
 861                         varflag = isdeclarationcmd(&argp->narg) ? 2 : 0;
 862                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 863         }
 864         appendarglist(&arglist, nullstr);
 865         expredir(cmd->ncmd.redirect);
 866         argc = arglist.count - 2;
 867         argv = &arglist.args[1];
 868
 869         argv[argc] = NULL;
 870         lastarg = NULL;
 871         if (iflag && funcnest == 0 && argc > 0)
 872                 lastarg = argv[argc - 1];
 873
 874         /* Print the command if xflag is set. */
 875         if (xflag)
 876                 xtracecommand(&varlist, argc, argv);
 877
 878         /* Now locate the command. */
 879         if (argc == 0) {
 880                 /* Variable assignment(s) without command */
 881                 cmdentry.cmdtype = CMDBUILTIN;
 882                 cmdentry.u.index = BLTINCMD;
 883                 cmdentry.special = 0;
 884         } else {
 885                 static const char PATH[] = "PATH=";
 886                 int cmd_flags = 0, bltinonly = 0;
 887
 888                 /*
 889                  * Modify the command lookup path, if a PATH= assignment
 890                  * is present
 891                  */
 892                 for (i = 0; i < varlist.count; i++)
 893                         if (strncmp(varlist.args[i], PATH, sizeof(PATH) - 1) == 0) {
 894                                 path = varlist.args[i] + sizeof(PATH) - 1;
 895                                 /*
 896                                  * On `PATH=... command`, we need to make
 897                                  * sure that the command isn't using the
 898                                  * non-updated hash table of the outer PATH
 899                                  * setting and we need to make sure that
 900                                  * the hash table isn't filled with items
 901                                  * from the temporary setting.
 902                                  *
 903                                  * It would be better to forbit using and
 904                                  * updating the table while this command
 905                                  * runs, by the command finding mechanism
 906                                  * is heavily integrated with hash handling,
 907                                  * so we just delete the hash before and after
 908                                  * the command runs. Partly deleting like
 909                                  * changepatch() does doesn't seem worth the
 910                                  * bookinging effort, since most such runs add
 911                                  * directories in front of the new PATH.
 912                                  */
 913                                 clearcmdentry();
 914                                 do_clearcmdentry = 1;
 915                         }
 916
 917                 for (;;) {
 918                         if (bltinonly) {
 919                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 920                                 if (cmdentry.u.index < 0) {
 921                                         cmdentry.u.index = BLTINCMD;
 922                                         argv--;
 923                                         argc++;
 924                                         break;
 925                                 }
 926                         } else
 927                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 928                         /* implement the bltin and command builtins here */
 929                         if (cmdentry.cmdtype != CMDBUILTIN)
 930                                 break;
 931                         if (cmdentry.u.index == BLTINCMD) {
 932                                 if (argc == 1)
 933                                         break;
 934                                 argv++;
 935                                 argc--;
 936                                 bltinonly = 1;
 937                         } else if (cmdentry.u.index == COMMANDCMD) {
 938                                 if (argc == 1)
 939                                         break;
 940                                 if (!strcmp(argv[1], "-p")) {
 941                                         if (argc == 2)
 942                                                 break;
 943                                         if (argv[2][0] == '-') {
 944                                                 if (strcmp(argv[2], "--"))
 945                                                         break;
 946                                                 if (argc == 3)
 947                                                         break;
 948                                                 argv += 3;
 949                                                 argc -= 3;
 950                                         } else {
 951                                                 argv += 2;
 952                                                 argc -= 2;
 953                                         }
 954                                         path = _PATH_STDPATH;
 955                                         clearcmdentry();
 956                                         do_clearcmdentry = 1;
 957                                 } else if (!strcmp(argv[1], "--")) {
 958                                         if (argc == 2)
 959                                                 break;
 960                                         argv += 2;
 961                                         argc -= 2;
 962                                 } else if (argv[1][0] == '-')
 963                                         break;
 964                                 else {
 965                                         argv++;
 966                                         argc--;
 967                                 }
 968                                 cmd_flags |= DO_NOFUNC;
 969                                 bltinonly = 0;
 970                         } else
 971                                 break;
 972                 }
 973                 /*
 974                  * Special builtins lose their special properties when
 975                  * called via 'command'.
 976                  */
 977                 if (cmd_flags & DO_NOFUNC)
 978                         cmdentry.special = 0;
 979         }
 980
 981         /* Fork off a child process if necessary. */
 982         if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 983             && ((flags & EV_EXIT) == 0 || have_traps()))
 984          || ((flags & EV_BACKCMD) != 0
 985             && (cmdentry.cmdtype != CMDBUILTIN ||
 986                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 987                 jp = makejob(cmd, 1);
 988                 mode = FORK_FG;
 989                 if (flags & EV_BACKCMD) {
 990                         mode = FORK_NOJOB;
 991                         if (pipe(pip) < 0)
 992                                 error("Pipe call failed: %s", strerror(errno));
 993                 }
 994                 if (cmdentry.cmdtype == CMDNORMAL &&
 995                     cmd->ncmd.redirect == NULL &&
 996                     varlist.count == 0 &&
 997                     (mode == FORK_FG || mode == FORK_NOJOB) &&
 998                     !disvforkset() && !iflag && !mflag) {
 999                         vforkexecshell(jp, argv, environment(), path,
1000                             cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL);
1001                         goto parent;
1002                 }
1003                 if (forkshell(jp, cmd, mode) != 0)
1004                         goto parent;    /* at end of routine */
1005                 if (flags & EV_BACKCMD) {
1006                         FORCEINTON;
1007                         close(pip[0]);
1008                         if (pip[1] != 1) {
1009                                 dup2(pip[1], 1);
1010                                 close(pip[1]);
1011                         }
1012                         flags &= ~EV_BACKCMD;
1013                 }
1014                 flags |= EV_EXIT;
1015         }
1016
1017         /* This is the child process if a fork occurred. */
1018         /* Execute the command. */
1019         if (cmdentry.cmdtype == CMDFUNCTION) {
1020 #ifdef DEBUG
1021                 trputs("Shell function:  ");  trargs(argv);
1022 #endif
1023                 saveparam = shellparam;
1024                 shellparam.malloc = 0;
1025                 shellparam.reset = 1;
1026                 shellparam.nparam = argc - 1;
1027                 shellparam.p = argv + 1;
1028                 shellparam.optp = NULL;
1029                 shellparam.optnext = NULL;
1030                 INTOFF;
1031                 savelocalvars = localvars;
1032                 localvars = NULL;
1033                 reffunc(cmdentry.u.func);
1034                 savehandler = handler;
1035                 if (setjmp(jmploc.loc)) {
1036                         popredir();
1037                         unreffunc(cmdentry.u.func);
1038                         poplocalvars();
1039                         localvars = savelocalvars;
1040                         freeparam(&shellparam);
1041                         shellparam = saveparam;
1042                         funcnest--;
1043                         handler = savehandler;
1044                         longjmp(handler->loc, 1);
1045                 }
1046                 handler = &jmploc;
1047                 funcnest++;
1048                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
1049                 INTON;
1050                 for (i = 0; i < varlist.count; i++)
1051                         mklocal(varlist.args[i]);
1052                 exitstatus = oexitstatus;
1053                 evaltree(getfuncnode(cmdentry.u.func),
1054                     flags & (EV_TESTED | EV_EXIT));
1055                 INTOFF;
1056                 unreffunc(cmdentry.u.func);
1057                 poplocalvars();
1058                 localvars = savelocalvars;
1059                 freeparam(&shellparam);
1060                 shellparam = saveparam;
1061                 handler = savehandler;
1062                 funcnest--;
1063                 popredir();
1064                 INTON;
1065                 if (evalskip == SKIPRETURN) {
1066                         evalskip = 0;
1067                         skipcount = 0;
1068                 }
1069                 if (jp)
1070                         exitshell(exitstatus);
1071         } else if (cmdentry.cmdtype == CMDBUILTIN) {
1072 #ifdef DEBUG
1073                 trputs("builtin command:  ");  trargs(argv);
1074 #endif
1075                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
1076                 if (flags == EV_BACKCMD) {
1077                         memout.nextc = memout.buf;
1078                         mode |= REDIR_BACKQ;
1079                 }
1080                 savecmdname = commandname;
1081                 savetopfile = getcurrentfile();
1082                 cmdenviron = &varlist;
1083                 e = -1;
1084                 savehandler = handler;
1085                 if (setjmp(jmploc.loc)) {
1086                         e = exception;
1087                         if (e == EXINT)
1088                                 exitstatus = SIGINT+128;
1089                         goto cmddone;
1090                 }
1091                 handler = &jmploc;
1092                 redirect(cmd->ncmd.redirect, mode);
1093                 outclearerror(out1);
1094                 /*
1095                  * If there is no command word, redirection errors should
1096                  * not be fatal but assignment errors should.
1097                  */
1098                 if (argc == 0)
1099                         cmdentry.special = 1;
1100                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1101                 if (argc > 0)
1102                         bltinsetlocale();
1103                 commandname = argv[0];
1104                 argptr = argv + 1;
1105                 nextopt_optptr = NULL;          /* initialize nextopt */
1106                 builtin_flags = flags;
1107                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1108                 flushall();
1109                 if (outiserror(out1)) {
1110                         warning("write error on stdout");
1111                         if (exitstatus == 0 || exitstatus == 1)
1112                                 exitstatus = 2;
1113                 }
1114 cmddone:
1115                 if (argc > 0)
1116                         bltinunsetlocale();
1117                 cmdenviron = NULL;
1118                 out1 = &output;
1119                 out2 = &errout;
1120                 freestdout();
1121                 handler = savehandler;
1122                 commandname = savecmdname;
1123                 if (jp)
1124                         exitshell(exitstatus);
1125                 if (flags == EV_BACKCMD) {
1126                         backcmd->buf = memout.buf;
1127                         backcmd->nleft = memout.buf != NULL ?
1128                             memout.nextc - memout.buf : 0;
1129                         memout.buf = NULL;
1130                         memout.nextc = NULL;
1131                         memout.bufend = NULL;
1132                         memout.bufsize = 64;
1133                 }
1134                 if (cmdentry.u.index != EXECCMD)
1135                         popredir();
1136                 if (e != -1) {
1137                         if (e != EXERROR || cmdentry.special)
1138                                 exraise(e);
1139                         popfilesupto(savetopfile);
1140                         if (flags != EV_BACKCMD)
1141                                 FORCEINTON;
1142                 }
1143         } else {
1144 #ifdef DEBUG
1145                 trputs("normal command:  ");  trargs(argv);
1146 #endif
1147                 redirect(cmd->ncmd.redirect, 0);
1148                 for (i = 0; i < varlist.count; i++)
1149                         setvareq(varlist.args[i], VEXPORT|VSTACK);
1150                 envp = environment();
1151                 shellexec(argv, envp, path, cmdentry.u.index);
1152                 /*NOTREACHED*/
1153         }
1154         goto out;
1155
1156 parent: /* parent process gets here (if we forked) */
1157         if (mode == FORK_FG) {  /* argument to fork */
1158                 INTOFF;
1159                 exitstatus = waitforjob(jp, &signaled);
1160                 INTON;
1161                 if (iflag && loopnest > 0 && signaled) {
1162                         evalskip = SKIPBREAK;
1163                         skipcount = loopnest;
1164                 }
1165         } else if (mode == FORK_NOJOB) {
1166                 backcmd->fd = pip[0];
1167                 close(pip[1]);
1168                 backcmd->jp = jp;
1169         }
1170
1171 out:
1172         if (lastarg)
1173                 setvar("_", lastarg, 0);
1174         if (do_clearcmdentry)
1175                 clearcmdentry();
1176 }
1177
1178
1179
1180 /*
1181  * Search for a command.  This is called before we fork so that the
1182  * location of the command will be available in the parent as well as
1183  * the child.  The check for "goodname" is an overly conservative
1184  * check that the name will not be subject to expansion.
1185  */
1186
1187 static void
1188 prehash(union node *n)
1189 {
1190         struct cmdentry entry;
1191
1192         if (n && n->type == NCMD && n->ncmd.args)
1193                 if (goodname(n->ncmd.args->narg.text))
1194                         find_command(n->ncmd.args->narg.text, &entry, 0,
1195                                      pathval());
1196 }
1197
1198
1199
1200 /*
1201  * Builtin commands.  Builtin commands whose functions are closely
1202  * tied to evaluation are implemented here.
1203  */
1204
1205 /*
1206  * No command given, a bltin command with no arguments, or a bltin command
1207  * with an invalid name.
1208  */
1209
1210 int
1211 bltincmd(int argc, char **argv)
1212 {
1213         if (argc > 1) {
1214                 out2fmt_flush("%s: not found\n", argv[1]);
1215                 return 127;
1216         }
1217         /*
1218          * Preserve exitstatus of a previous possible command substitution
1219          * as POSIX mandates
1220          */
1221         return exitstatus;
1222 }
1223
1224
1225 /*
1226  * Handle break and continue commands.  Break, continue, and return are
1227  * all handled by setting the evalskip flag.  The evaluation routines
1228  * above all check this flag, and if it is set they start skipping
1229  * commands rather than executing them.  The variable skipcount is
1230  * the number of loops to break/continue, or the number of function
1231  * levels to return.  (The latter is always 1.)  It should probably
1232  * be an error to break out of more loops than exist, but it isn't
1233  * in the standard shell so we don't make it one here.
1234  */
1235
1236 int
1237 breakcmd(int argc, char **argv)
1238 {
1239         long n;
1240         char *end;
1241
1242         if (argc > 1) {
1243                 /* Allow arbitrarily large numbers. */
1244                 n = strtol(argv[1], &end, 10);
1245                 if (!is_digit(argv[1][0]) || *end != '\0')
1246                         error("Illegal number: %s", argv[1]);
1247         } else
1248                 n = 1;
1249         if (n > loopnest)
1250                 n = loopnest;
1251         if (n > 0) {
1252                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1253                 skipcount = n;
1254         }
1255         return 0;
1256 }
1257
1258 /*
1259  * The `command' command.
1260  */
1261 int
1262 commandcmd(int argc __unused, char **argv __unused)
1263 {
1264         const char *path;
1265         int ch;
1266         int cmd = -1;
1267
1268         path = bltinlookup("PATH", 1);
1269
1270         while ((ch = nextopt("pvV")) != '\0') {
1271                 switch (ch) {
1272                 case 'p':
1273                         path = _PATH_STDPATH;
1274                         break;
1275                 case 'v':
1276                         cmd = TYPECMD_SMALLV;
1277                         break;
1278                 case 'V':
1279                         cmd = TYPECMD_BIGV;
1280                         break;
1281                 }
1282         }
1283
1284         if (cmd != -1) {
1285                 if (*argptr == NULL || argptr[1] != NULL)
1286                         error("wrong number of arguments");
1287                 return typecmd_impl(2, argptr - 1, cmd, path);
1288         }
1289         if (*argptr != NULL)
1290                 error("commandcmd bad call");
1291
1292         /*
1293          * Do nothing successfully if no command was specified;
1294          * ksh also does this.
1295          */
1296         return 0;
1297 }
1298
1299
1300 /*
1301  * The return command.
1302  */
1303
1304 int
1305 returncmd(int argc, char **argv)
1306 {
1307         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1308
1309         evalskip = SKIPRETURN;
1310         skipcount = 1;
1311         return ret;
1312 }
1313
1314
1315 int
1316 falsecmd(int argc __unused, char **argv __unused)
1317 {
1318         return 1;
1319 }
1320
1321
1322 int
1323 truecmd(int argc __unused, char **argv __unused)
1324 {
1325         return 0;
1326 }
1327
1328
1329 int
1330 execcmd(int argc, char **argv)
1331 {
1332         int i;
1333
1334         /*
1335          * Because we have historically not supported any options,
1336          * only treat "--" specially.
1337          */
1338         if (argc > 1 && strcmp(argv[1], "--") == 0)
1339                 argc--, argv++;
1340         if (argc > 1) {
1341                 iflag = 0;              /* exit on error */
1342                 mflag = 0;
1343                 optschanged();
1344                 for (i = 0; i < cmdenviron->count; i++)
1345                         setvareq(cmdenviron->args[i], VEXPORT|VSTACK);
1346                 shellexec(argv + 1, environment(), pathval(), 0);
1347
1348         }
1349         return 0;
1350 }
1351
1352
1353 int
1354 timescmd(int argc __unused, char **argv __unused)
1355 {
1356         struct rusage ru;
1357         long shumins, shsmins, chumins, chsmins;
1358         double shusecs, shssecs, chusecs, chssecs;
1359
1360         if (getrusage(RUSAGE_SELF, &ru) < 0)
1361                 return 1;
1362         shumins = ru.ru_utime.tv_sec / 60;
1363         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1364         shsmins = ru.ru_stime.tv_sec / 60;
1365         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1366         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1367                 return 1;
1368         chumins = ru.ru_utime.tv_sec / 60;
1369         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1370         chsmins = ru.ru_stime.tv_sec / 60;
1371         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1372         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1373             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1374         return 0;
1375 }