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  * @(#)eval.c   8.9 (Berkeley) 6/8/95
  33  * $FreeBSD: head/bin/sh/eval.c 253658 2013-07-25 19:48:15Z jilles $
  34  */
  35
  36 #include <sys/time.h>
  37 #include <sys/resource.h>
  38 #include <sys/wait.h> /* For WIFSIGNALED(status) */
  39
  40 #include <errno.h>
  41 #include <paths.h>
  42 #include <signal.h>
  43 #include <stdlib.h>
  44 #include <unistd.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 const char *commandname;
  82 struct strlist *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         funcnest = 0;
 110 }
 111
 112
 113 /*
 114  * The eval command.
 115  */
 116
 117 int
 118 evalcmd(int argc, char **argv)
 119 {
 120         char *p;
 121         char *concat;
 122         char **ap;
 123
 124         if (argc > 1) {
 125                 p = argv[1];
 126                 if (argc > 2) {
 127                         STARTSTACKSTR(concat);
 128                         ap = argv + 2;
 129                         for (;;) {
 130                                 STPUTS(p, concat);
 131                                 if ((p = *ap++) == NULL)
 132                                         break;
 133                                 STPUTC(' ', concat);
 134                         }
 135                         STPUTC('\0', concat);
 136                         p = grabstackstr(concat);
 137                 }
 138                 evalstring(p, builtin_flags);
 139         } else
 140                 exitstatus = 0;
 141         return exitstatus;
 142 }
 143
 144
 145 /*
 146  * Execute a command or commands contained in a string.
 147  */
 148
 149 void
 150 evalstring(char *s, int flags)
 151 {
 152         union node *n;
 153         struct stackmark smark;
 154         int flags_exit;
 155         int any;
 156
 157         flags_exit = flags & EV_EXIT;
 158         flags &= ~EV_EXIT;
 159         any = 0;
 160         setstackmark(&smark);
 161         setinputstring(s, 1);
 162         while ((n = parsecmd(0)) != NEOF) {
 163                 if (n != NULL && !nflag) {
 164                         if (flags_exit && preadateof())
 165                                 evaltree(n, flags | EV_EXIT);
 166                         else
 167                                 evaltree(n, flags);
 168                         any = 1;
 169                 }
 170                 popstackmark(&smark);
 171                 setstackmark(&smark);
 172         }
 173         popfile();
 174         popstackmark(&smark);
 175         if (!any)
 176                 exitstatus = 0;
 177         if (flags_exit)
 178                 exraise(EXEXIT);
 179 }
 180
 181
 182 /*
 183  * Evaluate a parse tree.  The value is left in the global variable
 184  * exitstatus.
 185  */
 186
 187 void
 188 evaltree(union node *n, int flags)
 189 {
 190         int do_etest;
 191         union node *next;
 192         struct stackmark smark;
 193
 194         setstackmark(&smark);
 195         do_etest = 0;
 196         if (n == NULL) {
 197                 TRACE(("evaltree(NULL) called\n"));
 198                 exitstatus = 0;
 199                 goto out;
 200         }
 201         do {
 202                 next = NULL;
 203 #ifndef NO_HISTORY
 204                 displayhist = 1;        /* show history substitutions done with fc */
 205 #endif
 206                 TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
 207                 switch (n->type) {
 208                 case NSEMI:
 209                         evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
 210                         if (evalskip)
 211                                 goto out;
 212                         next = n->nbinary.ch2;
 213                         break;
 214                 case NAND:
 215                         evaltree(n->nbinary.ch1, EV_TESTED);
 216                         if (evalskip || exitstatus != 0) {
 217                                 goto out;
 218                         }
 219                         next = n->nbinary.ch2;
 220                         break;
 221                 case NOR:
 222                         evaltree(n->nbinary.ch1, EV_TESTED);
 223                         if (evalskip || exitstatus == 0)
 224                                 goto out;
 225                         next = n->nbinary.ch2;
 226                         break;
 227                 case NREDIR:
 228                         evalredir(n, flags);
 229                         break;
 230                 case NSUBSHELL:
 231                         evalsubshell(n, flags);
 232                         do_etest = !(flags & EV_TESTED);
 233                         break;
 234                 case NBACKGND:
 235                         evalsubshell(n, flags);
 236                         break;
 237                 case NIF: {
 238                         evaltree(n->nif.test, EV_TESTED);
 239                         if (evalskip)
 240                                 goto out;
 241                         if (exitstatus == 0)
 242                                 next = n->nif.ifpart;
 243                         else if (n->nif.elsepart)
 244                                 next = n->nif.elsepart;
 245                         else
 246                                 exitstatus = 0;
 247                         break;
 248                 }
 249                 case NWHILE:
 250                 case NUNTIL:
 251                         evalloop(n, flags & ~EV_EXIT);
 252                         break;
 253                 case NFOR:
 254                         evalfor(n, flags & ~EV_EXIT);
 255                         break;
 256                 case NCASE:
 257                         next = evalcase(n);
 258                         break;
 259                 case NCLIST:
 260                         next = n->nclist.body;
 261                         break;
 262                 case NCLISTFALLTHRU:
 263                         if (n->nclist.body) {
 264                                 evaltree(n->nclist.body, flags & ~EV_EXIT);
 265                                 if (evalskip)
 266                                         goto out;
 267                         }
 268                         next = n->nclist.next;
 269                         break;
 270                 case NDEFUN:
 271                         defun(n->narg.text, n->narg.next);
 272                         exitstatus = 0;
 273                         break;
 274                 case NNOT:
 275                         evaltree(n->nnot.com, EV_TESTED);
 276                         if (evalskip)
 277                                 goto out;
 278                         exitstatus = !exitstatus;
 279                         break;
 280
 281                 case NPIPE:
 282                         evalpipe(n);
 283                         do_etest = !(flags & EV_TESTED);
 284                         break;
 285                 case NCMD:
 286                         evalcommand(n, flags, NULL);
 287                         do_etest = !(flags & EV_TESTED);
 288                         break;
 289                 default:
 290                         out1fmt("Node type = %d\n", n->type);
 291                         flushout(&output);
 292                         break;
 293                 }
 294                 n = next;
 295                 popstackmark(&smark);
 296                 setstackmark(&smark);
 297         } while (n != NULL);
 298 out:
 299         popstackmark(&smark);
 300         if (pendingsig)
 301                 dotrap();
 302         if (eflag && exitstatus != 0 && do_etest)
 303                 exitshell(exitstatus);
 304         if (flags & EV_EXIT)
 305                 exraise(EXEXIT);
 306 }
 307
 308
 309 static void
 310 evalloop(union node *n, int flags)
 311 {
 312         int status;
 313
 314         loopnest++;
 315         status = 0;
 316         for (;;) {
 317                 evaltree(n->nbinary.ch1, EV_TESTED);
 318                 if (evalskip) {
 319 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
 320                                 evalskip = 0;
 321                                 continue;
 322                         }
 323                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 324                                 evalskip = 0;
 325                         if (evalskip == SKIPFUNC || evalskip == SKIPFILE)
 326                                 status = exitstatus;
 327                         break;
 328                 }
 329                 if (n->type == NWHILE) {
 330                         if (exitstatus != 0)
 331                                 break;
 332                 } else {
 333                         if (exitstatus == 0)
 334                                 break;
 335                 }
 336                 evaltree(n->nbinary.ch2, flags);
 337                 status = exitstatus;
 338                 if (evalskip)
 339                         goto skipping;
 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         struct strlist *sp;
 353         int status;
 354
 355         arglist.lastp = &arglist.list;
 356         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 357                 oexitstatus = exitstatus;
 358                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 359         }
 360         *arglist.lastp = NULL;
 361
 362         loopnest++;
 363         status = 0;
 364         for (sp = arglist.list ; sp ; sp = sp->next) {
 365                 setvar(n->nfor.var, sp->text, 0);
 366                 evaltree(n->nfor.body, flags);
 367                 status = exitstatus;
 368                 if (evalskip) {
 369                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 370                                 evalskip = 0;
 371                                 continue;
 372                         }
 373                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 374                                 evalskip = 0;
 375                         break;
 376                 }
 377         }
 378         loopnest--;
 379         exitstatus = status;
 380 }
 381
 382
 383 /*
 384  * Evaluate a case statement, returning the selected tree.
 385  *
 386  * The exit status needs care to get right.
 387  */
 388
 389 static union node *
 390 evalcase(union node *n)
 391 {
 392         union node *cp;
 393         union node *patp;
 394         struct arglist arglist;
 395
 396         arglist.lastp = &arglist.list;
 397         oexitstatus = exitstatus;
 398         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 399         for (cp = n->ncase.cases ; cp ; cp = cp->nclist.next) {
 400                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 401                         if (casematch(patp, arglist.list->text)) {
 402                                 while (cp->nclist.next &&
 403                                     cp->type == NCLISTFALLTHRU &&
 404                                     cp->nclist.body == NULL)
 405                                         cp = cp->nclist.next;
 406                                 if (cp->nclist.next &&
 407                                     cp->type == NCLISTFALLTHRU)
 408                                         return (cp);
 409                                 if (cp->nclist.body == NULL)
 410                                         exitstatus = 0;
 411                                 return (cp->nclist.body);
 412                         }
 413                 }
 414         }
 415         exitstatus = 0;
 416         return (NULL);
 417 }
 418
 419
 420
 421 /*
 422  * Kick off a subshell to evaluate a tree.
 423  */
 424
 425 static void
 426 evalsubshell(union node *n, int flags)
 427 {
 428         struct job *jp;
 429         int backgnd = (n->type == NBACKGND);
 430
 431         oexitstatus = exitstatus;
 432         expredir(n->nredir.redirect);
 433         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
 434             forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
 435                 if (backgnd)
 436                         flags &=~ EV_TESTED;
 437                 redirect(n->nredir.redirect, 0);
 438                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 439         } else if (!backgnd) {
 440                 INTOFF;
 441                 exitstatus = waitforjob(jp, NULL);
 442                 INTON;
 443         } else
 444                 exitstatus = 0;
 445 }
 446
 447
 448 /*
 449  * Evaluate a redirected compound command.
 450  */
 451
 452 static void
 453 evalredir(union node *n, int flags)
 454 {
 455         struct jmploc jmploc;
 456         struct jmploc *savehandler;
 457         volatile int in_redirect = 1;
 458
 459         oexitstatus = exitstatus;
 460         expredir(n->nredir.redirect);
 461         savehandler = handler;
 462         if (setjmp(jmploc.loc)) {
 463                 int e;
 464
 465                 handler = savehandler;
 466                 e = exception;
 467                 popredir();
 468                 if (e == EXERROR || e == EXEXEC) {
 469                         if (in_redirect) {
 470                                 exitstatus = 2;
 471                                 return;
 472                         }
 473                 }
 474                 longjmp(handler->loc, 1);
 475         } else {
 476                 INTOFF;
 477                 handler = &jmploc;
 478                 redirect(n->nredir.redirect, REDIR_PUSH);
 479                 in_redirect = 0;
 480                 INTON;
 481                 evaltree(n->nredir.n, flags);
 482         }
 483         INTOFF;
 484         handler = savehandler;
 485         popredir();
 486         INTON;
 487 }
 488
 489
 490 static void
 491 exphere(union node *redir, struct arglist *fn)
 492 {
 493         struct jmploc jmploc;
 494         struct jmploc *savehandler;
 495         struct localvar *savelocalvars;
 496         int need_longjmp = 0;
 497
 498         redir->nhere.expdoc = nullstr;
 499         savelocalvars = localvars;
 500         localvars = NULL;
 501         forcelocal++;
 502         savehandler = handler;
 503         if (setjmp(jmploc.loc))
 504                 need_longjmp = exception != EXERROR && exception != EXEXEC;
 505         else {
 506                 handler = &jmploc;
 507                 expandarg(redir->nhere.doc, fn, 0);
 508                 redir->nhere.expdoc = fn->list->text;
 509                 INTOFF;
 510         }
 511         handler = savehandler;
 512         forcelocal--;
 513         poplocalvars();
 514         localvars = savelocalvars;
 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                 fn.lastp = &fn.list;
 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 | EXP_REDIR);
 540                         redir->nfile.expfname = fn.list->text;
 541                         break;
 542                 case NFROMFD:
 543                 case NTOFD:
 544                         if (redir->ndup.vname) {
 545                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
 546                                 fixredir(redir, fn.list->text, 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, 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
 649         setstackmark(&smark);
 650         result->fd = -1;
 651         result->buf = NULL;
 652         result->nleft = 0;
 653         result->jp = NULL;
 654         if (n == NULL) {
 655                 exitstatus = 0;
 656                 goto out;
 657         }
 658         exitstatus = oexitstatus;
 659         if (is_valid_fast_cmdsubst(n)) {
 660                 savelocalvars = localvars;
 661                 localvars = NULL;
 662                 forcelocal++;
 663                 savehandler = handler;
 664                 if (setjmp(jmploc.loc)) {
 665                         if (exception == EXERROR || exception == EXEXEC)
 666                                 exitstatus = 2;
 667                         else if (exception != 0) {
 668                                 handler = savehandler;
 669                                 forcelocal--;
 670                                 poplocalvars();
 671                                 localvars = savelocalvars;
 672                                 longjmp(handler->loc, 1);
 673                         }
 674                 } else {
 675                         handler = &jmploc;
 676                         evalcommand(n, EV_BACKCMD, result);
 677                 }
 678                 handler = savehandler;
 679                 forcelocal--;
 680                 poplocalvars();
 681                 localvars = savelocalvars;
 682         } else {
 683                 if (pipe(pip) < 0)
 684                         error("Pipe call failed: %s", strerror(errno));
 685                 jp = makejob(n, 1);
 686                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 687                         FORCEINTON;
 688                         close(pip[0]);
 689                         if (pip[1] != 1) {
 690                                 dup2(pip[1], 1);
 691                                 close(pip[1]);
 692                         }
 693                         evaltree(n, EV_EXIT);
 694                 }
 695                 close(pip[1]);
 696                 result->fd = pip[0];
 697                 result->jp = jp;
 698         }
 699 out:
 700         popstackmark(&smark);
 701         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 702                 result->fd, result->buf, result->nleft, result->jp));
 703 }
 704
 705 static int
 706 mustexpandto(const char *argtext, const char *mask)
 707 {
 708         for (;;) {
 709                 if (*argtext == CTLQUOTEMARK || *argtext == CTLQUOTEEND) {
 710                         argtext++;
 711                         continue;
 712                 }
 713                 if (*argtext == CTLESC)
 714                         argtext++;
 715                 else if (BASESYNTAX[(int)*argtext] == CCTL)
 716                         return (0);
 717                 if (*argtext != *mask)
 718                         return (0);
 719                 if (*argtext == '\0')
 720                         return (1);
 721                 argtext++;
 722                 mask++;
 723         }
 724 }
 725
 726 static int
 727 isdeclarationcmd(struct narg *arg)
 728 {
 729         int have_command = 0;
 730
 731         if (arg == NULL)
 732                 return (0);
 733         while (mustexpandto(arg->text, "command")) {
 734                 have_command = 1;
 735                 arg = &arg->next->narg;
 736                 if (arg == NULL)
 737                         return (0);
 738                 /*
 739                  * To also allow "command -p" and "command --" as part of
 740                  * a declaration command, add code here.
 741                  * We do not do this, as ksh does not do it either and it
 742                  * is not required by POSIX.
 743                  */
 744         }
 745         return (mustexpandto(arg->text, "export") ||
 746             mustexpandto(arg->text, "readonly") ||
 747             (mustexpandto(arg->text, "local") &&
 748                 (have_command || !isfunc("local"))));
 749 }
 750
 751 /*
 752  * Check if a builtin can safely be executed in the same process,
 753  * even though it should be in a subshell (command substitution).
 754  * Note that jobid, jobs, times and trap can show information not
 755  * available in a child process; this is deliberate.
 756  * The arguments should already have been expanded.
 757  */
 758 static int
 759 safe_builtin(int idx, int argc, char **argv)
 760 {
 761         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
 762             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
 763             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
 764             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
 765             idx == TYPECMD)
 766                 return (1);
 767         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 768             idx == UMASKCMD)
 769                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 770         if (idx == SETCMD)
 771                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 772                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 773                     argv[1][2] == '\0'));
 774         return (0);
 775 }
 776
 777 /*
 778  * Execute a simple command.
 779  * Note: This may or may not return if (flags & EV_EXIT).
 780  */
 781
 782 static void
 783 evalcommand(union node *cmd, int flgs, struct backcmd *backcmd)
 784 {
 785         union node *argp;
 786         struct arglist arglist;
 787         struct arglist varlist;
 788         volatile int flags = flgs;
 789         char **volatile argv;
 790         volatile int argc;
 791         char **envp;
 792         int varflag;
 793         struct strlist *sp;
 794         int mode;
 795         int pip[2];
 796         struct cmdentry cmdentry;
 797         struct job *volatile jp;
 798         struct jmploc jmploc;
 799         struct jmploc *savehandler;
 800         const char *savecmdname;
 801         struct shparam saveparam;
 802         struct localvar *savelocalvars;
 803         struct parsefile *savetopfile;
 804         volatile int e;
 805         char *volatile lastarg;
 806         int realstatus;
 807         volatile int do_clearcmdentry;
 808         const char *path = pathval();
 809
 810         /* First expand the arguments. */
 811         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 812         arglist.lastp = &arglist.list;
 813         varlist.lastp = &varlist.list;
 814         varflag = 1;
 815         jp = NULL;
 816         do_clearcmdentry = 0;
 817         oexitstatus = exitstatus;
 818         exitstatus = 0;
 819         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 820                 if (varflag && isassignment(argp->narg.text)) {
 821                         expandarg(argp, varflag == 1 ? &varlist : &arglist,
 822                             EXP_VARTILDE);
 823                         continue;
 824                 } else if (varflag == 1)
 825                         varflag = isdeclarationcmd(&argp->narg) ? 2 : 0;
 826                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 827         }
 828         *arglist.lastp = NULL;
 829         *varlist.lastp = NULL;
 830         expredir(cmd->ncmd.redirect);
 831         argc = 0;
 832         for (sp = arglist.list ; sp ; sp = sp->next)
 833                 argc++;
 834         /* Add one slot at the beginning for tryexec(). */
 835         argv = stalloc(sizeof (char *) * (argc + 2));
 836         argv++;
 837
 838         for (sp = arglist.list ; sp ; sp = sp->next) {
 839                 TRACE(("evalcommand arg: %s\n", sp->text));
 840                 *argv++ = sp->text;
 841         }
 842         *argv = NULL;
 843         lastarg = NULL;
 844         if (iflag && funcnest == 0 && argc > 0)
 845                 lastarg = argv[-1];
 846         argv -= argc;
 847
 848         /* Print the command if xflag is set. */
 849         if (xflag) {
 850                 char sep = 0;
 851                 const char *p, *ps4;
 852                 ps4 = expandstr(ps4val());
 853                 out2str(ps4 != NULL ? ps4 : ps4val());
 854                 for (sp = varlist.list ; sp ; sp = sp->next) {
 855                         if (sep != 0)
 856                                 out2c(' ');
 857                         p = strchr(sp->text, '=');
 858                         if (p != NULL) {
 859                                 p++;
 860                                 outbin(sp->text, p - sp->text, out2);
 861                                 out2qstr(p);
 862                         } else
 863                                 out2qstr(sp->text);
 864                         sep = ' ';
 865                 }
 866                 for (sp = arglist.list ; sp ; sp = sp->next) {
 867                         if (sep != 0)
 868                                 out2c(' ');
 869                         /* Disambiguate command looking like assignment. */
 870                         if (sp == arglist.list &&
 871                                         strchr(sp->text, '=') != NULL &&
 872                                         strchr(sp->text, '\'') == NULL) {
 873                                 out2c('\'');
 874                                 out2str(sp->text);
 875                                 out2c('\'');
 876                         } else
 877                                 out2qstr(sp->text);
 878                         sep = ' ';
 879                 }
 880                 out2c('\n');
 881                 flushout(&errout);
 882         }
 883
 884         /* Now locate the command. */
 885         if (argc == 0) {
 886                 /* Variable assignment(s) without command */
 887                 cmdentry.cmdtype = CMDBUILTIN;
 888                 cmdentry.u.index = BLTINCMD;
 889                 cmdentry.special = 0;
 890         } else {
 891                 static const char PATH[] = "PATH=";
 892                 int cmd_flags = 0, bltinonly = 0;
 893
 894                 /*
 895                  * Modify the command lookup path, if a PATH= assignment
 896                  * is present
 897                  */
 898                 for (sp = varlist.list ; sp ; sp = sp->next)
 899                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 900                                 path = sp->text + sizeof(PATH) - 1;
 901                                 /*
 902                                  * On `PATH=... command`, we need to make
 903                                  * sure that the command isn't using the
 904                                  * non-updated hash table of the outer PATH
 905                                  * setting and we need to make sure that
 906                                  * the hash table isn't filled with items
 907                                  * from the temporary setting.
 908                                  *
 909                                  * It would be better to forbit using and
 910                                  * updating the table while this command
 911                                  * runs, by the command finding mechanism
 912                                  * is heavily integrated with hash handling,
 913                                  * so we just delete the hash before and after
 914                                  * the command runs. Partly deleting like
 915                                  * changepatch() does doesn't seem worth the
 916                                  * bookinging effort, since most such runs add
 917                                  * directories in front of the new PATH.
 918                                  */
 919                                 clearcmdentry();
 920                                 do_clearcmdentry = 1;
 921                         }
 922
 923                 for (;;) {
 924                         if (bltinonly) {
 925                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 926                                 if (cmdentry.u.index < 0) {
 927                                         cmdentry.u.index = BLTINCMD;
 928                                         argv--;
 929                                         argc++;
 930                                         break;
 931                                 }
 932                         } else
 933                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 934                         /* implement the bltin and command builtins here */
 935                         if (cmdentry.cmdtype != CMDBUILTIN)
 936                                 break;
 937                         if (cmdentry.u.index == BLTINCMD) {
 938                                 if (argc == 1)
 939                                         break;
 940                                 argv++;
 941                                 argc--;
 942                                 bltinonly = 1;
 943                         } else if (cmdentry.u.index == COMMANDCMD) {
 944                                 if (argc == 1)
 945                                         break;
 946                                 if (!strcmp(argv[1], "-p")) {
 947                                         if (argc == 2)
 948                                                 break;
 949                                         if (argv[2][0] == '-') {
 950                                                 if (strcmp(argv[2], "--"))
 951                                                         break;
 952                                                 if (argc == 3)
 953                                                         break;
 954                                                 argv += 3;
 955                                                 argc -= 3;
 956                                         } else {
 957                                                 argv += 2;
 958                                                 argc -= 2;
 959                                         }
 960                                         path = _PATH_STDPATH;
 961                                         clearcmdentry();
 962                                         do_clearcmdentry = 1;
 963                                 } else if (!strcmp(argv[1], "--")) {
 964                                         if (argc == 2)
 965                                                 break;
 966                                         argv += 2;
 967                                         argc -= 2;
 968                                 } else if (argv[1][0] == '-')
 969                                         break;
 970                                 else {
 971                                         argv++;
 972                                         argc--;
 973                                 }
 974                                 cmd_flags |= DO_NOFUNC;
 975                                 bltinonly = 0;
 976                         } else
 977                                 break;
 978                 }
 979                 /*
 980                  * Special builtins lose their special properties when
 981                  * called via 'command'.
 982                  */
 983                 if (cmd_flags & DO_NOFUNC)
 984                         cmdentry.special = 0;
 985         }
 986
 987         /* Fork off a child process if necessary. */
 988         if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 989             && ((flags & EV_EXIT) == 0 || have_traps()))
 990          || ((flags & EV_BACKCMD) != 0
 991             && (cmdentry.cmdtype != CMDBUILTIN ||
 992                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 993                 jp = makejob(cmd, 1);
 994                 mode = FORK_FG;
 995                 if (flags & EV_BACKCMD) {
 996                         mode = FORK_NOJOB;
 997                         if (pipe(pip) < 0)
 998                                 error("Pipe call failed: %s", strerror(errno));
 999                 }
1000                 if (cmdentry.cmdtype == CMDNORMAL &&
1001                     cmd->ncmd.redirect == NULL &&
1002                     varlist.list == NULL &&
1003                     (mode == FORK_FG || mode == FORK_NOJOB) &&
1004                     !disvforkset() && !iflag && !mflag) {
1005                         vforkexecshell(jp, argv, environment(), path,
1006                             cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL);
1007                         goto parent;
1008                 }
1009                 if (forkshell(jp, cmd, mode) != 0)
1010                         goto parent;    /* at end of routine */
1011                 if (flags & EV_BACKCMD) {
1012                         FORCEINTON;
1013                         close(pip[0]);
1014                         if (pip[1] != 1) {
1015                                 dup2(pip[1], 1);
1016                                 close(pip[1]);
1017                         }
1018                         flags &= ~EV_BACKCMD;
1019                 }
1020                 flags |= EV_EXIT;
1021         }
1022
1023         /* This is the child process if a fork occurred. */
1024         /* Execute the command. */
1025         if (cmdentry.cmdtype == CMDFUNCTION) {
1026 #ifdef DEBUG
1027                 trputs("Shell function:  ");  trargs(argv);
1028 #endif
1029                 saveparam = shellparam;
1030                 shellparam.malloc = 0;
1031                 shellparam.reset = 1;
1032                 shellparam.nparam = argc - 1;
1033                 shellparam.p = argv + 1;
1034                 shellparam.optnext = NULL;
1035                 INTOFF;
1036                 savelocalvars = localvars;
1037                 localvars = NULL;
1038                 reffunc(cmdentry.u.func);
1039                 savehandler = handler;
1040                 if (setjmp(jmploc.loc)) {
1041                         freeparam(&shellparam);
1042                         shellparam = saveparam;
1043                         popredir();
1044                         unreffunc(cmdentry.u.func);
1045                         poplocalvars();
1046                         localvars = savelocalvars;
1047                         funcnest--;
1048                         handler = savehandler;
1049                         longjmp(handler->loc, 1);
1050                 }
1051                 handler = &jmploc;
1052                 funcnest++;
1053                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
1054                 INTON;
1055                 for (sp = varlist.list ; sp ; sp = sp->next)
1056                         mklocal(sp->text);
1057                 exitstatus = oexitstatus;
1058                 evaltree(getfuncnode(cmdentry.u.func),
1059                     flags & (EV_TESTED | EV_EXIT));
1060                 INTOFF;
1061                 unreffunc(cmdentry.u.func);
1062                 poplocalvars();
1063                 localvars = savelocalvars;
1064                 freeparam(&shellparam);
1065                 shellparam = saveparam;
1066                 handler = savehandler;
1067                 funcnest--;
1068                 popredir();
1069                 INTON;
1070                 if (evalskip == SKIPFUNC) {
1071                         evalskip = 0;
1072                         skipcount = 0;
1073                 }
1074                 if (jp)
1075                         exitshell(exitstatus);
1076         } else if (cmdentry.cmdtype == CMDBUILTIN) {
1077 #ifdef DEBUG
1078                 trputs("builtin command:  ");  trargs(argv);
1079 #endif
1080                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
1081                 if (flags == EV_BACKCMD) {
1082                         memout.nleft = 0;
1083                         memout.nextc = memout.buf;
1084                         memout.bufsize = 64;
1085                         mode |= REDIR_BACKQ;
1086                 }
1087                 savecmdname = commandname;
1088                 savetopfile = getcurrentfile();
1089                 cmdenviron = varlist.list;
1090                 e = -1;
1091                 savehandler = handler;
1092                 if (setjmp(jmploc.loc)) {
1093                         e = exception;
1094                         if (e == EXINT)
1095                                 exitstatus = SIGINT+128;
1096                         else if (e != EXEXIT)
1097                                 exitstatus = 2;
1098                         goto cmddone;
1099                 }
1100                 handler = &jmploc;
1101                 redirect(cmd->ncmd.redirect, mode);
1102                 outclearerror(out1);
1103                 /*
1104                  * If there is no command word, redirection errors should
1105                  * not be fatal but assignment errors should.
1106                  */
1107                 if (argc == 0)
1108                         cmdentry.special = 1;
1109                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1110                 if (argc > 0)
1111                         bltinsetlocale();
1112                 commandname = argv[0];
1113                 argptr = argv + 1;
1114                 nextopt_optptr = NULL;          /* initialize nextopt */
1115                 builtin_flags = flags;
1116                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1117                 flushall();
1118                 if (outiserror(out1)) {
1119                         warning("write error on stdout");
1120                         if (exitstatus == 0 || exitstatus == 1)
1121                                 exitstatus = 2;
1122                 }
1123 cmddone:
1124                 if (argc > 0)
1125                         bltinunsetlocale();
1126                 cmdenviron = NULL;
1127                 out1 = &output;
1128                 out2 = &errout;
1129                 freestdout();
1130                 handler = savehandler;
1131                 commandname = savecmdname;
1132                 if (jp)
1133                         exitshell(exitstatus);
1134                 if (flags == EV_BACKCMD) {
1135                         backcmd->buf = memout.buf;
1136                         backcmd->nleft = memout.nextc - memout.buf;
1137                         memout.buf = NULL;
1138                 }
1139                 if (cmdentry.u.index != EXECCMD)
1140                         popredir();
1141                 if (e != -1) {
1142                         if ((e != EXERROR && e != EXEXEC)
1143                             || cmdentry.special)
1144                                 exraise(e);
1145                         popfilesupto(savetopfile);
1146                         if (flags != EV_BACKCMD)
1147                                 FORCEINTON;
1148                 }
1149         } else {
1150 #ifdef DEBUG
1151                 trputs("normal command:  ");  trargs(argv);
1152 #endif
1153                 redirect(cmd->ncmd.redirect, 0);
1154                 for (sp = varlist.list ; sp ; sp = sp->next)
1155                         setvareq(sp->text, VEXPORT|VSTACK);
1156                 envp = environment();
1157                 shellexec(argv, envp, path, cmdentry.u.index);
1158                 /*NOTREACHED*/
1159         }
1160         goto out;
1161
1162 parent: /* parent process gets here (if we forked) */
1163         if (mode == FORK_FG) {  /* argument to fork */
1164                 INTOFF;
1165                 exitstatus = waitforjob(jp, &realstatus);
1166                 INTON;
1167                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1168                         evalskip = SKIPBREAK;
1169                         skipcount = loopnest;
1170                 }
1171         } else if (mode == FORK_NOJOB) {
1172                 backcmd->fd = pip[0];
1173                 close(pip[1]);
1174                 backcmd->jp = jp;
1175         }
1176
1177 out:
1178         if (lastarg)
1179                 setvar("_", lastarg, 0);
1180         if (do_clearcmdentry)
1181                 clearcmdentry();
1182 }
1183
1184
1185
1186 /*
1187  * Search for a command.  This is called before we fork so that the
1188  * location of the command will be available in the parent as well as
1189  * the child.  The check for "goodname" is an overly conservative
1190  * check that the name will not be subject to expansion.
1191  */
1192
1193 static void
1194 prehash(union node *n)
1195 {
1196         struct cmdentry entry;
1197
1198         if (n && n->type == NCMD && n->ncmd.args)
1199                 if (goodname(n->ncmd.args->narg.text))
1200                         find_command(n->ncmd.args->narg.text, &entry, 0,
1201                                      pathval());
1202 }
1203
1204
1205
1206 /*
1207  * Builtin commands.  Builtin commands whose functions are closely
1208  * tied to evaluation are implemented here.
1209  */
1210
1211 /*
1212  * No command given, a bltin command with no arguments, or a bltin command
1213  * with an invalid name.
1214  */
1215
1216 int
1217 bltincmd(int argc, char **argv)
1218 {
1219         if (argc > 1) {
1220                 out2fmt_flush("%s: not found\n", argv[1]);
1221                 return 127;
1222         }
1223         /*
1224          * Preserve exitstatus of a previous possible redirection
1225          * as POSIX mandates
1226          */
1227         return exitstatus;
1228 }
1229
1230
1231 /*
1232  * Handle break and continue commands.  Break, continue, and return are
1233  * all handled by setting the evalskip flag.  The evaluation routines
1234  * above all check this flag, and if it is set they start skipping
1235  * commands rather than executing them.  The variable skipcount is
1236  * the number of loops to break/continue, or the number of function
1237  * levels to return.  (The latter is always 1.)  It should probably
1238  * be an error to break out of more loops than exist, but it isn't
1239  * in the standard shell so we don't make it one here.
1240  */
1241
1242 int
1243 breakcmd(int argc, char **argv)
1244 {
1245         int n = argc > 1 ? number(argv[1]) : 1;
1246
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         if (funcnest) {
1308                 evalskip = SKIPFUNC;
1309                 skipcount = 1;
1310         } else {
1311                 /* skip the rest of the file */
1312                 evalskip = SKIPFILE;
1313                 skipcount = 1;
1314         }
1315         return ret;
1316 }
1317
1318
1319 int
1320 falsecmd(int argc __unused, char **argv __unused)
1321 {
1322         return 1;
1323 }
1324
1325
1326 int
1327 truecmd(int argc __unused, char **argv __unused)
1328 {
1329         return 0;
1330 }
1331
1332
1333 int
1334 execcmd(int argc, char **argv)
1335 {
1336         /*
1337          * Because we have historically not supported any options,
1338          * only treat "--" specially.
1339          */
1340         if (argc > 1 && strcmp(argv[1], "--") == 0)
1341                 argc--, argv++;
1342         if (argc > 1) {
1343                 struct strlist *sp;
1344
1345                 iflag = 0;              /* exit on error */
1346                 mflag = 0;
1347                 optschanged();
1348                 for (sp = cmdenviron; sp ; sp = sp->next)
1349                         setvareq(sp->text, VEXPORT|VSTACK);
1350                 shellexec(argv + 1, environment(), pathval(), 0);
1351
1352         }
1353         return 0;
1354 }
1355
1356
1357 int
1358 timescmd(int argc __unused, char **argv __unused)
1359 {
1360         struct rusage ru;
1361         long shumins, shsmins, chumins, chsmins;
1362         double shusecs, shssecs, chusecs, chssecs;
1363
1364         if (getrusage(RUSAGE_SELF, &ru) < 0)
1365                 return 1;
1366         shumins = ru.ru_utime.tv_sec / 60;
1367         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1368         shsmins = ru.ru_stime.tv_sec / 60;
1369         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1370         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1371                 return 1;
1372         chumins = ru.ru_utime.tv_sec / 60;
1373         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1374         chsmins = ru.ru_stime.tv_sec / 60;
1375         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1376         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1377             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1378         return 0;
1379 }