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. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * @(#)eval.c   8.9 (Berkeley) 6/8/95
  37  * $FreeBSD: src/bin/sh/eval.c,v 1.115 2011/12/28 22:10:12 jilles Exp $
  38  */
  39
  40 #include <sys/time.h>
  41 #include <sys/resource.h>
  42 #include <sys/wait.h> /* For WIFSIGNALED(status) */
  43
  44 #include <errno.h>
  45 #include <paths.h>
  46 #include <signal.h>
  47 #include <stdlib.h>
  48 #include <unistd.h>
  49
  50 /*
  51  * Evaluate a command.
  52  */
  53
  54 #include "shell.h"
  55 #include "nodes.h"
  56 #include "syntax.h"
  57 #include "expand.h"
  58 #include "parser.h"
  59 #include "jobs.h"
  60 #include "eval.h"
  61 #include "builtins.h"
  62 #include "options.h"
  63 #include "exec.h"
  64 #include "redir.h"
  65 #include "input.h"
  66 #include "output.h"
  67 #include "trap.h"
  68 #include "var.h"
  69 #include "memalloc.h"
  70 #include "error.h"
  71 #include "show.h"
  72 #include "mystring.h"
  73 #ifndef NO_HISTORY
  74 #include "myhistedit.h"
  75 #endif
  76
  77
  78 int evalskip;                   /* set if we are skipping commands */
  79 static int skipcount;           /* number of levels to skip */
  80 MKINIT int loopnest;            /* current loop nesting level */
  81 int funcnest;                   /* depth of function calls */
  82 static int builtin_flags;       /* evalcommand flags for builtins */
  83
  84
  85 const char *commandname;
  86 struct strlist *cmdenviron;
  87 int exitstatus;                 /* exit status of last command */
  88 int oexitstatus;                /* saved exit status */
  89
  90
  91 static void evalloop(union node *, int);
  92 static void evalfor(union node *, int);
  93 static union node *evalcase(union node *, int);
  94 static void evalsubshell(union node *, int);
  95 static void evalredir(union node *, int);
  96 static void expredir(union node *);
  97 static void evalpipe(union node *);
  98 static int is_valid_fast_cmdsubst(union node *n);
  99 static void evalcommand(union node *, int, struct backcmd *);
 100 static void prehash(union node *);
 101
 102
 103 /*
 104  * Called to reset things after an exception.
 105  */
 106
 107 #ifdef mkinit
 108 INCLUDE "eval.h"
 109
 110 RESET {
 111         evalskip = 0;
 112         loopnest = 0;
 113         funcnest = 0;
 114 }
 115 #endif
 116
 117
 118
 119 /*
 120  * The eval command.
 121  */
 122
 123 int
 124 evalcmd(int argc, char **argv)
 125 {
 126         char *p;
 127         char *concat;
 128         char **ap;
 129
 130         if (argc > 1) {
 131                 p = argv[1];
 132                 if (argc > 2) {
 133                         STARTSTACKSTR(concat);
 134                         ap = argv + 2;
 135                         for (;;) {
 136                                 STPUTS(p, concat);
 137                                 if ((p = *ap++) == NULL)
 138                                         break;
 139                                 STPUTC(' ', concat);
 140                         }
 141                         STPUTC('\0', concat);
 142                         p = grabstackstr(concat);
 143                 }
 144                 evalstring(p, builtin_flags);
 145         } else
 146                 exitstatus = 0;
 147         return exitstatus;
 148 }
 149
 150
 151 /*
 152  * Execute a command or commands contained in a string.
 153  */
 154
 155 void
 156 evalstring(char *s, int flags)
 157 {
 158         union node *n;
 159         struct stackmark smark;
 160         int flags_exit;
 161         int any;
 162
 163         flags_exit = flags & EV_EXIT;
 164         flags &= ~EV_EXIT;
 165         any = 0;
 166         setstackmark(&smark);
 167         setinputstring(s, 1);
 168         while ((n = parsecmd(0)) != NEOF) {
 169                 if (n != NULL && !nflag) {
 170                         if (flags_exit && preadateof())
 171                                 evaltree(n, flags | EV_EXIT);
 172                         else
 173                                 evaltree(n, flags);
 174                         any = 1;
 175                 }
 176                 popstackmark(&smark);
 177         }
 178         popfile();
 179         popstackmark(&smark);
 180         if (!any)
 181                 exitstatus = 0;
 182         if (flags_exit)
 183                 exraise(EXEXIT);
 184 }
 185
 186
 187 /*
 188  * Evaluate a parse tree.  The value is left in the global variable
 189  * exitstatus.
 190  */
 191
 192 void
 193 evaltree(union node *n, int flags)
 194 {
 195         int do_etest;
 196         union node *next;
 197
 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, flags);
 261                         break;
 262                 case NDEFUN:
 263                         defun(n->narg.text, n->narg.next);
 264                         exitstatus = 0;
 265                         break;
 266                 case NNOT:
 267                         evaltree(n->nnot.com, EV_TESTED);
 268                         exitstatus = !exitstatus;
 269                         break;
 270
 271                 case NPIPE:
 272                         evalpipe(n);
 273                         do_etest = !(flags & EV_TESTED);
 274                         break;
 275                 case NCMD:
 276                         evalcommand(n, flags, NULL);
 277                         do_etest = !(flags & EV_TESTED);
 278                         break;
 279                 default:
 280                         out1fmt("Node type = %d\n", n->type);
 281                         flushout(&output);
 282                         break;
 283                 }
 284                 n = next;
 285         } while (n != NULL);
 286 out:
 287         if (pendingsigs)
 288                 dotrap();
 289         if (eflag && exitstatus != 0 && do_etest)
 290                 exitshell(exitstatus);
 291         if (flags & EV_EXIT)
 292                 exraise(EXEXIT);
 293 }
 294
 295
 296 static void
 297 evalloop(union node *n, int flags)
 298 {
 299         int status;
 300
 301         loopnest++;
 302         status = 0;
 303         for (;;) {
 304                 evaltree(n->nbinary.ch1, EV_TESTED);
 305                 if (evalskip) {
 306 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
 307                                 evalskip = 0;
 308                                 continue;
 309                         }
 310                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 311                                 evalskip = 0;
 312                         if (evalskip == SKIPFUNC || evalskip == SKIPFILE)
 313                                 status = exitstatus;
 314                         break;
 315                 }
 316                 if (n->type == NWHILE) {
 317                         if (exitstatus != 0)
 318                                 break;
 319                 } else {
 320                         if (exitstatus == 0)
 321                                 break;
 322                 }
 323                 evaltree(n->nbinary.ch2, flags);
 324                 status = exitstatus;
 325                 if (evalskip)
 326                         goto skipping;
 327         }
 328         loopnest--;
 329         exitstatus = status;
 330 }
 331
 332
 333
 334 static void
 335 evalfor(union node *n, int flags)
 336 {
 337         struct arglist arglist;
 338         union node *argp;
 339         struct strlist *sp;
 340         struct stackmark smark;
 341
 342         setstackmark(&smark);
 343         arglist.lastp = &arglist.list;
 344         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 345                 oexitstatus = exitstatus;
 346                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 347         }
 348         *arglist.lastp = NULL;
 349
 350         exitstatus = 0;
 351         loopnest++;
 352         for (sp = arglist.list ; sp ; sp = sp->next) {
 353                 setvar(n->nfor.var, sp->text, 0);
 354                 evaltree(n->nfor.body, flags);
 355                 if (evalskip) {
 356                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 357                                 evalskip = 0;
 358                                 continue;
 359                         }
 360                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 361                                 evalskip = 0;
 362                         break;
 363                 }
 364         }
 365         loopnest--;
 366         popstackmark(&smark);
 367 }
 368
 369
 370
 371 static union node *
 372 evalcase(union node *n, int flags)
 373 {
 374         union node *cp;
 375         union node *patp;
 376         struct arglist arglist;
 377         struct stackmark smark;
 378
 379         setstackmark(&smark);
 380         arglist.lastp = &arglist.list;
 381         oexitstatus = exitstatus;
 382         exitstatus = 0;
 383         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 384         for (cp = n->ncase.cases ; cp ; cp = cp->nclist.next) {
 385                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 386                         if (casematch(patp, arglist.list->text)) {
 387                                 popstackmark(&smark);
 388                                 while (cp->nclist.next &&
 389                                     cp->type == NCLISTFALLTHRU) {
 390                                         evaltree(cp->nclist.body,
 391                                             flags & ~EV_EXIT);
 392                                         if (evalskip != 0)
 393                                                 return (NULL);
 394                                         cp = cp->nclist.next;
 395                                 }
 396                                 return (cp->nclist.body);
 397                         }
 398                 }
 399         }
 400         popstackmark(&smark);
 401         return (NULL);
 402 }
 403
 404
 405
 406 /*
 407  * Kick off a subshell to evaluate a tree.
 408  */
 409
 410 static void
 411 evalsubshell(union node *n, int flags)
 412 {
 413         struct job *jp;
 414         int backgnd = (n->type == NBACKGND);
 415
 416         oexitstatus = exitstatus;
 417         expredir(n->nredir.redirect);
 418         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
 419             forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
 420                 if (backgnd)
 421                         flags &=~ EV_TESTED;
 422                 redirect(n->nredir.redirect, 0);
 423                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 424         } else if (!backgnd) {
 425                 INTOFF;
 426                 exitstatus = waitforjob(jp, NULL);
 427                 INTON;
 428         } else
 429                 exitstatus = 0;
 430 }
 431
 432
 433 /*
 434  * Evaluate a redirected compound command.
 435  */
 436
 437 static void
 438 evalredir(union node *n, int flags)
 439 {
 440         struct jmploc jmploc;
 441         struct jmploc *savehandler;
 442         volatile int in_redirect = 1;
 443
 444         oexitstatus = exitstatus;
 445         expredir(n->nredir.redirect);
 446         savehandler = handler;
 447         if (setjmp(jmploc.loc)) {
 448                 int e;
 449
 450                 handler = savehandler;
 451                 e = exception;
 452                 popredir();
 453                 if (e == EXERROR || e == EXEXEC) {
 454                         if (in_redirect) {
 455                                 exitstatus = 2;
 456                                 return;
 457                         }
 458                 }
 459                 longjmp(handler->loc, 1);
 460         } else {
 461                 INTOFF;
 462                 handler = &jmploc;
 463                 redirect(n->nredir.redirect, REDIR_PUSH);
 464                 in_redirect = 0;
 465                 INTON;
 466                 evaltree(n->nredir.n, flags);
 467         }
 468         INTOFF;
 469         handler = savehandler;
 470         popredir();
 471         INTON;
 472 }
 473
 474
 475 /*
 476  * Compute the names of the files in a redirection list.
 477  */
 478
 479 static void
 480 expredir(union node *n)
 481 {
 482         union node *redir;
 483
 484         for (redir = n ; redir ; redir = redir->nfile.next) {
 485                 struct arglist fn;
 486                 fn.lastp = &fn.list;
 487                 switch (redir->type) {
 488                 case NFROM:
 489                 case NTO:
 490                 case NFROMTO:
 491                 case NAPPEND:
 492                 case NCLOBBER:
 493                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 494                         redir->nfile.expfname = fn.list->text;
 495                         break;
 496                 case NFROMFD:
 497                 case NTOFD:
 498                         if (redir->ndup.vname) {
 499                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
 500                                 fixredir(redir, fn.list->text, 1);
 501                         }
 502                         break;
 503                 }
 504         }
 505 }
 506
 507
 508
 509 /*
 510  * Evaluate a pipeline.  All the processes in the pipeline are children
 511  * of the process creating the pipeline.  (This differs from some versions
 512  * of the shell, which make the last process in a pipeline the parent
 513  * of all the rest.)
 514  */
 515
 516 static void
 517 evalpipe(union node *n)
 518 {
 519         struct job *jp;
 520         struct nodelist *lp;
 521         int pipelen;
 522         int prevfd;
 523         int pip[2];
 524
 525         TRACE(("evalpipe(%p) called\n", (void *)n));
 526         pipelen = 0;
 527         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
 528                 pipelen++;
 529         INTOFF;
 530         jp = makejob(n, pipelen);
 531         prevfd = -1;
 532         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
 533                 prehash(lp->n);
 534                 pip[1] = -1;
 535                 if (lp->next) {
 536                         if (pipe(pip) < 0) {
 537                                 if (prevfd >= 0)
 538                                         close(prevfd);
 539                                 error("Pipe call failed: %s", strerror(errno));
 540                         }
 541                 }
 542                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
 543                         INTON;
 544                         if (prevfd > 0) {
 545                                 dup2(prevfd, 0);
 546                                 close(prevfd);
 547                         }
 548                         if (pip[1] >= 0) {
 549                                 if (!(prevfd >= 0 && pip[0] == 0))
 550                                         close(pip[0]);
 551                                 if (pip[1] != 1) {
 552                                         dup2(pip[1], 1);
 553                                         close(pip[1]);
 554                                 }
 555                         }
 556                         evaltree(lp->n, EV_EXIT);
 557                 }
 558                 if (prevfd >= 0)
 559                         close(prevfd);
 560                 prevfd = pip[0];
 561                 if (pip[1] != -1)
 562                         close(pip[1]);
 563         }
 564         INTON;
 565         if (n->npipe.backgnd == 0) {
 566                 INTOFF;
 567                 exitstatus = waitforjob(jp, NULL);
 568                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 569                 INTON;
 570         } else
 571                 exitstatus = 0;
 572 }
 573
 574
 575
 576 static int
 577 is_valid_fast_cmdsubst(union node *n)
 578 {
 579
 580         return (n->type == NCMD);
 581 }
 582
 583 /*
 584  * Execute a command inside back quotes.  If it's a builtin command, we
 585  * want to save its output in a block obtained from malloc.  Otherwise
 586  * we fork off a subprocess and get the output of the command via a pipe.
 587  * Should be called with interrupts off.
 588  */
 589
 590 void
 591 evalbackcmd(union node *n, struct backcmd *result)
 592 {
 593         int pip[2];
 594         struct job *jp;
 595         struct stackmark smark;         /* unnecessary */
 596         struct jmploc jmploc;
 597         struct jmploc *savehandler;
 598         struct localvar *savelocalvars;
 599
 600         setstackmark(&smark);
 601         result->fd = -1;
 602         result->buf = NULL;
 603         result->nleft = 0;
 604         result->jp = NULL;
 605         if (n == NULL) {
 606                 exitstatus = 0;
 607                 goto out;
 608         }
 609         if (is_valid_fast_cmdsubst(n)) {
 610                 exitstatus = oexitstatus;
 611                 savelocalvars = localvars;
 612                 localvars = NULL;
 613                 forcelocal++;
 614                 savehandler = handler;
 615                 if (setjmp(jmploc.loc)) {
 616                         if (exception == EXERROR || exception == EXEXEC)
 617                                 exitstatus = 2;
 618                         else if (exception != 0) {
 619                                 handler = savehandler;
 620                                 forcelocal--;
 621                                 poplocalvars();
 622                                 localvars = savelocalvars;
 623                                 longjmp(handler->loc, 1);
 624                         }
 625                 } else {
 626                         handler = &jmploc;
 627                         evalcommand(n, EV_BACKCMD, result);
 628                 }
 629                 handler = savehandler;
 630                 forcelocal--;
 631                 poplocalvars();
 632                 localvars = savelocalvars;
 633         } else {
 634                 exitstatus = 0;
 635                 if (pipe(pip) < 0)
 636                         error("Pipe call failed: %s", strerror(errno));
 637                 jp = makejob(n, 1);
 638                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 639                         FORCEINTON;
 640                         close(pip[0]);
 641                         if (pip[1] != 1) {
 642                                 dup2(pip[1], 1);
 643                                 close(pip[1]);
 644                         }
 645                         evaltree(n, EV_EXIT);
 646                 }
 647                 close(pip[1]);
 648                 result->fd = pip[0];
 649                 result->jp = jp;
 650         }
 651 out:
 652         popstackmark(&smark);
 653         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 654                 result->fd, result->buf, result->nleft, result->jp));
 655 }
 656
 657 /*
 658  * Check if a builtin can safely be executed in the same process,
 659  * even though it should be in a subshell (command substitution).
 660  * Note that jobid, jobs, times and trap can show information not
 661  * available in a child process; this is deliberate.
 662  * The arguments should already have been expanded.
 663  */
 664 static int
 665 safe_builtin(int idx, int argc, char **argv)
 666 {
 667         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
 668             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
 669             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
 670             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
 671             idx == TYPECMD)
 672                 return (1);
 673         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 674             idx == UMASKCMD)
 675                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 676         if (idx == SETCMD)
 677                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 678                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 679                     argv[1][2] == '\0'));
 680         return (0);
 681 }
 682
 683 /*
 684  * Execute a simple command.
 685  * Note: This may or may not return if (flags & EV_EXIT).
 686  */
 687
 688 static void
 689 evalcommand(union node *cmd, int flgs, struct backcmd *backcmd)
 690 {
 691         struct stackmark smark;
 692         union node *argp;
 693         struct arglist arglist;
 694         struct arglist varlist;
 695         volatile int flags = flgs;
 696         char **volatile argv;
 697         volatile int argc;
 698         char **envp;
 699         int varflag;
 700         struct strlist *sp;
 701         int mode;
 702         int pip[2];
 703         struct cmdentry cmdentry;
 704         struct job *volatile jp;
 705         struct jmploc jmploc;
 706         struct jmploc *savehandler;
 707         const char *savecmdname;
 708         struct shparam saveparam;
 709         struct localvar *savelocalvars;
 710         struct parsefile *savetopfile;
 711         volatile int e;
 712         char *volatile lastarg;
 713         int realstatus;
 714         volatile int do_clearcmdentry;
 715         const char *path = pathval();
 716
 717         /* First expand the arguments. */
 718         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 719         setstackmark(&smark);
 720         arglist.lastp = &arglist.list;
 721         varlist.lastp = &varlist.list;
 722         varflag = 1;
 723         jp = NULL;
 724         do_clearcmdentry = 0;
 725         oexitstatus = exitstatus;
 726         exitstatus = 0;
 727         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 728                 if (varflag && isassignment(argp->narg.text)) {
 729                         expandarg(argp, &varlist, EXP_VARTILDE);
 730                         continue;
 731                 }
 732                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 733                 varflag = 0;
 734         }
 735         *arglist.lastp = NULL;
 736         *varlist.lastp = NULL;
 737         expredir(cmd->ncmd.redirect);
 738         argc = 0;
 739         for (sp = arglist.list ; sp ; sp = sp->next)
 740                 argc++;
 741         /* Add one slot at the beginning for tryexec(). */
 742         argv = stalloc(sizeof (char *) * (argc + 2));
 743         argv++;
 744
 745         for (sp = arglist.list ; sp ; sp = sp->next) {
 746                 TRACE(("evalcommand arg: %s\n", sp->text));
 747                 *argv++ = sp->text;
 748         }
 749         *argv = NULL;
 750         lastarg = NULL;
 751         if (iflag && funcnest == 0 && argc > 0)
 752                 lastarg = argv[-1];
 753         argv -= argc;
 754
 755         /* Print the command if xflag is set. */
 756         if (xflag) {
 757                 char sep = 0;
 758                 const char *p, *ps4;
 759                 ps4 = expandstr(ps4val());
 760                 out2str(ps4 != NULL ? ps4 : ps4val());
 761                 for (sp = varlist.list ; sp ; sp = sp->next) {
 762                         if (sep != 0)
 763                                 out2c(' ');
 764                         p = strchr(sp->text, '=');
 765                         if (p != NULL) {
 766                                 p++;
 767                                 outbin(sp->text, p - sp->text, out2);
 768                                 out2qstr(p);
 769                         } else
 770                                 out2qstr(sp->text);
 771                         sep = ' ';
 772                 }
 773                 for (sp = arglist.list ; sp ; sp = sp->next) {
 774                         if (sep != 0)
 775                                 out2c(' ');
 776                         /* Disambiguate command looking like assignment. */
 777                         if (sp == arglist.list &&
 778                                         strchr(sp->text, '=') != NULL &&
 779                                         strchr(sp->text, '\'') == NULL) {
 780                                 out2c('\'');
 781                                 out2str(sp->text);
 782                                 out2c('\'');
 783                         } else
 784                                 out2qstr(sp->text);
 785                         sep = ' ';
 786                 }
 787                 out2c('\n');
 788                 flushout(&errout);
 789         }
 790
 791         /* Now locate the command. */
 792         if (argc == 0) {
 793                 /* Variable assignment(s) without command */
 794                 cmdentry.cmdtype = CMDBUILTIN;
 795                 cmdentry.u.index = BLTINCMD;
 796                 cmdentry.special = 0;
 797         } else {
 798                 static const char PATH[] = "PATH=";
 799                 int cmd_flags = 0, bltinonly = 0;
 800
 801                 /*
 802                  * Modify the command lookup path, if a PATH= assignment
 803                  * is present
 804                  */
 805                 for (sp = varlist.list ; sp ; sp = sp->next)
 806                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 807                                 path = sp->text + sizeof(PATH) - 1;
 808                                 /*
 809                                  * On `PATH=... command`, we need to make
 810                                  * sure that the command isn't using the
 811                                  * non-updated hash table of the outer PATH
 812                                  * setting and we need to make sure that
 813                                  * the hash table isn't filled with items
 814                                  * from the temporary setting.
 815                                  *
 816                                  * It would be better to forbit using and
 817                                  * updating the table while this command
 818                                  * runs, by the command finding mechanism
 819                                  * is heavily integrated with hash handling,
 820                                  * so we just delete the hash before and after
 821                                  * the command runs. Partly deleting like
 822                                  * changepatch() does doesn't seem worth the
 823                                  * bookinging effort, since most such runs add
 824                                  * directories in front of the new PATH.
 825                                  */
 826                                 clearcmdentry();
 827                                 do_clearcmdentry = 1;
 828                         }
 829
 830                 for (;;) {
 831                         if (bltinonly) {
 832                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 833                                 if (cmdentry.u.index < 0) {
 834                                         cmdentry.u.index = BLTINCMD;
 835                                         argv--;
 836                                         argc++;
 837                                         break;
 838                                 }
 839                         } else
 840                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 841                         /* implement the bltin and command builtins here */
 842                         if (cmdentry.cmdtype != CMDBUILTIN)
 843                                 break;
 844                         if (cmdentry.u.index == BLTINCMD) {
 845                                 if (argc == 1)
 846                                         break;
 847                                 argv++;
 848                                 argc--;
 849                                 bltinonly = 1;
 850                         } else if (cmdentry.u.index == COMMANDCMD) {
 851                                 if (argc == 1)
 852                                         break;
 853                                 if (!strcmp(argv[1], "-p")) {
 854                                         if (argc == 2)
 855                                                 break;
 856                                         if (argv[2][0] == '-') {
 857                                                 if (strcmp(argv[2], "--"))
 858                                                         break;
 859                                                 if (argc == 3)
 860                                                         break;
 861                                                 argv += 3;
 862                                                 argc -= 3;
 863                                         } else {
 864                                                 argv += 2;
 865                                                 argc -= 2;
 866                                         }
 867                                         path = _PATH_STDPATH;
 868                                         clearcmdentry();
 869                                         do_clearcmdentry = 1;
 870                                 } else if (!strcmp(argv[1], "--")) {
 871                                         if (argc == 2)
 872                                                 break;
 873                                         argv += 2;
 874                                         argc -= 2;
 875                                 } else if (argv[1][0] == '-')
 876                                         break;
 877                                 else {
 878                                         argv++;
 879                                         argc--;
 880                                 }
 881                                 cmd_flags |= DO_NOFUNC;
 882                                 bltinonly = 0;
 883                         } else
 884                                 break;
 885                 }
 886                 /*
 887                  * Special builtins lose their special properties when
 888                  * called via 'command'.
 889                  */
 890                 if (cmd_flags & DO_NOFUNC)
 891                         cmdentry.special = 0;
 892         }
 893
 894         /* Fork off a child process if necessary. */
 895         if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 896             && ((flags & EV_EXIT) == 0 || have_traps()))
 897          || ((flags & EV_BACKCMD) != 0
 898             && (cmdentry.cmdtype != CMDBUILTIN ||
 899                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 900                 jp = makejob(cmd, 1);
 901                 mode = FORK_FG;
 902                 if (flags & EV_BACKCMD) {
 903                         mode = FORK_NOJOB;
 904                         if (pipe(pip) < 0)
 905                                 error("Pipe call failed: %s", strerror(errno));
 906                 }
 907                 if (forkshell(jp, cmd, mode) != 0)
 908                         goto parent;    /* at end of routine */
 909                 if (flags & EV_BACKCMD) {
 910                         FORCEINTON;
 911                         close(pip[0]);
 912                         if (pip[1] != 1) {
 913                                 dup2(pip[1], 1);
 914                                 close(pip[1]);
 915                         }
 916                         flags &= ~EV_BACKCMD;
 917                 }
 918                 flags |= EV_EXIT;
 919         }
 920
 921         /* This is the child process if a fork occurred. */
 922         /* Execute the command. */
 923         if (cmdentry.cmdtype == CMDFUNCTION) {
 924 #ifdef DEBUG
 925                 trputs("Shell function:  ");  trargs(argv);
 926 #endif
 927                 saveparam = shellparam;
 928                 shellparam.malloc = 0;
 929                 shellparam.reset = 1;
 930                 shellparam.nparam = argc - 1;
 931                 shellparam.p = argv + 1;
 932                 shellparam.optnext = NULL;
 933                 INTOFF;
 934                 savelocalvars = localvars;
 935                 localvars = NULL;
 936                 reffunc(cmdentry.u.func);
 937                 savehandler = handler;
 938                 if (setjmp(jmploc.loc)) {
 939                         freeparam(&shellparam);
 940                         shellparam = saveparam;
 941                         popredir();
 942                         unreffunc(cmdentry.u.func);
 943                         poplocalvars();
 944                         localvars = savelocalvars;
 945                         funcnest--;
 946                         handler = savehandler;
 947                         longjmp(handler->loc, 1);
 948                 }
 949                 handler = &jmploc;
 950                 funcnest++;
 951                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
 952                 INTON;
 953                 for (sp = varlist.list ; sp ; sp = sp->next)
 954                         mklocal(sp->text);
 955                 exitstatus = oexitstatus;
 956                 evaltree(getfuncnode(cmdentry.u.func),
 957                     flags & (EV_TESTED | EV_EXIT));
 958                 INTOFF;
 959                 unreffunc(cmdentry.u.func);
 960                 poplocalvars();
 961                 localvars = savelocalvars;
 962                 freeparam(&shellparam);
 963                 shellparam = saveparam;
 964                 handler = savehandler;
 965                 funcnest--;
 966                 popredir();
 967                 INTON;
 968                 if (evalskip == SKIPFUNC) {
 969                         evalskip = 0;
 970                         skipcount = 0;
 971                 }
 972                 if (jp)
 973                         exitshell(exitstatus);
 974         } else if (cmdentry.cmdtype == CMDBUILTIN) {
 975 #ifdef DEBUG
 976                 trputs("builtin command:  ");  trargs(argv);
 977 #endif
 978                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
 979                 if (flags == EV_BACKCMD) {
 980                         memout.nleft = 0;
 981                         memout.nextc = memout.buf;
 982                         memout.bufsize = 64;
 983                         mode |= REDIR_BACKQ;
 984                 }
 985                 savecmdname = commandname;
 986                 savetopfile = getcurrentfile();
 987                 cmdenviron = varlist.list;
 988                 e = -1;
 989                 savehandler = handler;
 990                 if (setjmp(jmploc.loc)) {
 991                         e = exception;
 992                         if (e == EXINT)
 993                                 exitstatus = SIGINT+128;
 994                         else if (e != EXEXIT)
 995                                 exitstatus = 2;
 996                         goto cmddone;
 997                 }
 998                 handler = &jmploc;
 999                 redirect(cmd->ncmd.redirect, mode);
1000                 /*
1001                  * If there is no command word, redirection errors should
1002                  * not be fatal but assignment errors should.
1003                  */
1004                 if (argc == 0)
1005                         cmdentry.special = 1;
1006                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1007                 if (argc > 0)
1008                         bltinsetlocale();
1009                 commandname = argv[0];
1010                 argptr = argv + 1;
1011                 nextopt_optptr = NULL;          /* initialize nextopt */
1012                 builtin_flags = flags;
1013                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1014                 flushall();
1015 cmddone:
1016                 if (argc > 0)
1017                         bltinunsetlocale();
1018                 cmdenviron = NULL;
1019                 out1 = &output;
1020                 out2 = &errout;
1021                 freestdout();
1022                 handler = savehandler;
1023                 commandname = savecmdname;
1024                 if (jp)
1025                         exitshell(exitstatus);
1026                 if (flags == EV_BACKCMD) {
1027                         backcmd->buf = memout.buf;
1028                         backcmd->nleft = memout.nextc - memout.buf;
1029                         memout.buf = NULL;
1030                 }
1031                 if (cmdentry.u.index != EXECCMD)
1032                         popredir();
1033                 if (e != -1) {
1034                         if ((e != EXERROR && e != EXEXEC)
1035                             || cmdentry.special)
1036                                 exraise(e);
1037                         popfilesupto(savetopfile);
1038                         if (flags != EV_BACKCMD)
1039                                 FORCEINTON;
1040                 }
1041         } else {
1042 #ifdef DEBUG
1043                 trputs("normal command:  ");  trargs(argv);
1044 #endif
1045                 redirect(cmd->ncmd.redirect, 0);
1046                 for (sp = varlist.list ; sp ; sp = sp->next)
1047                         setvareq(sp->text, VEXPORT|VSTACK);
1048                 envp = environment();
1049                 shellexec(argv, envp, path, cmdentry.u.index);
1050                 /*NOTREACHED*/
1051         }
1052         goto out;
1053
1054 parent: /* parent process gets here (if we forked) */
1055         if (mode == FORK_FG) {  /* argument to fork */
1056                 INTOFF;
1057                 exitstatus = waitforjob(jp, &realstatus);
1058                 INTON;
1059                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1060                         evalskip = SKIPBREAK;
1061                         skipcount = loopnest;
1062                 }
1063         } else if (mode == FORK_NOJOB) {
1064                 backcmd->fd = pip[0];
1065                 close(pip[1]);
1066                 backcmd->jp = jp;
1067         }
1068
1069 out:
1070         if (lastarg)
1071                 setvar("_", lastarg, 0);
1072         if (do_clearcmdentry)
1073                 clearcmdentry();
1074         popstackmark(&smark);
1075 }
1076
1077
1078
1079 /*
1080  * Search for a command.  This is called before we fork so that the
1081  * location of the command will be available in the parent as well as
1082  * the child.  The check for "goodname" is an overly conservative
1083  * check that the name will not be subject to expansion.
1084  */
1085
1086 static void
1087 prehash(union node *n)
1088 {
1089         struct cmdentry entry;
1090
1091         if (n && n->type == NCMD && n->ncmd.args)
1092                 if (goodname(n->ncmd.args->narg.text))
1093                         find_command(n->ncmd.args->narg.text, &entry, 0,
1094                                      pathval());
1095 }
1096
1097
1098
1099 /*
1100  * Builtin commands.  Builtin commands whose functions are closely
1101  * tied to evaluation are implemented here.
1102  */
1103
1104 /*
1105  * No command given, a bltin command with no arguments, or a bltin command
1106  * with an invalid name.
1107  */
1108
1109 int
1110 bltincmd(int argc, char **argv)
1111 {
1112         if (argc > 1) {
1113                 out2fmt_flush("%s: not found\n", argv[1]);
1114                 return 127;
1115         }
1116         /*
1117          * Preserve exitstatus of a previous possible redirection
1118          * as POSIX mandates
1119          */
1120         return exitstatus;
1121 }
1122
1123
1124 /*
1125  * Handle break and continue commands.  Break, continue, and return are
1126  * all handled by setting the evalskip flag.  The evaluation routines
1127  * above all check this flag, and if it is set they start skipping
1128  * commands rather than executing them.  The variable skipcount is
1129  * the number of loops to break/continue, or the number of function
1130  * levels to return.  (The latter is always 1.)  It should probably
1131  * be an error to break out of more loops than exist, but it isn't
1132  * in the standard shell so we don't make it one here.
1133  */
1134
1135 int
1136 breakcmd(int argc, char **argv)
1137 {
1138         int n = argc > 1 ? number(argv[1]) : 1;
1139
1140         if (n > loopnest)
1141                 n = loopnest;
1142         if (n > 0) {
1143                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1144                 skipcount = n;
1145         }
1146         return 0;
1147 }
1148
1149 /*
1150  * The `command' command.
1151  */
1152 int
1153 commandcmd(int argc, char **argv)
1154 {
1155         const char *path;
1156         int ch;
1157         int cmd = -1;
1158
1159         path = bltinlookup("PATH", 1);
1160
1161         optind = optreset = 1;
1162         opterr = 0;
1163         while ((ch = getopt(argc, argv, "pvV")) != -1) {
1164                 switch (ch) {
1165                 case 'p':
1166                         path = _PATH_STDPATH;
1167                         break;
1168                 case 'v':
1169                         cmd = TYPECMD_SMALLV;
1170                         break;
1171                 case 'V':
1172                         cmd = TYPECMD_BIGV;
1173                         break;
1174                 case '?':
1175                 default:
1176                         error("unknown option: -%c", optopt);
1177                 }
1178         }
1179         argc -= optind;
1180         argv += optind;
1181
1182         if (cmd != -1) {
1183                 if (argc != 1)
1184                         error("wrong number of arguments");
1185                 return typecmd_impl(2, argv - 1, cmd, path);
1186         }
1187         if (argc != 0)
1188                 error("commandcmd bad call");
1189
1190         /*
1191          * Do nothing successfully if no command was specified;
1192          * ksh also does this.
1193          */
1194         return(0);
1195 }
1196
1197
1198 /*
1199  * The return command.
1200  */
1201
1202 int
1203 returncmd(int argc, char **argv)
1204 {
1205         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1206
1207         if (funcnest) {
1208                 evalskip = SKIPFUNC;
1209                 skipcount = 1;
1210         } else {
1211                 /* skip the rest of the file */
1212                 evalskip = SKIPFILE;
1213                 skipcount = 1;
1214         }
1215         return ret;
1216 }
1217
1218
1219 int
1220 falsecmd(int argc __unused, char **argv __unused)
1221 {
1222         return 1;
1223 }
1224
1225
1226 int
1227 truecmd(int argc __unused, char **argv __unused)
1228 {
1229         return 0;
1230 }
1231
1232
1233 int
1234 execcmd(int argc, char **argv)
1235 {
1236         /*
1237          * Because we have historically not supported any options,
1238          * only treat "--" specially.
1239          */
1240         if (argc > 1 && strcmp(argv[1], "--") == 0)
1241                 argc--, argv++;
1242         if (argc > 1) {
1243                 struct strlist *sp;
1244
1245                 iflag = 0;              /* exit on error */
1246                 mflag = 0;
1247                 optschanged();
1248                 for (sp = cmdenviron; sp ; sp = sp->next)
1249                         setvareq(sp->text, VEXPORT|VSTACK);
1250                 shellexec(argv + 1, environment(), pathval(), 0);
1251
1252         }
1253         return 0;
1254 }
1255
1256
1257 int
1258 timescmd(int argc __unused, char **argv __unused)
1259 {
1260         struct rusage ru;
1261         long shumins, shsmins, chumins, chsmins;
1262         double shusecs, shssecs, chusecs, chssecs;
1263
1264         if (getrusage(RUSAGE_SELF, &ru) < 0)
1265                 return 1;
1266         shumins = ru.ru_utime.tv_sec / 60;
1267         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1268         shsmins = ru.ru_stime.tv_sec / 60;
1269         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1270         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1271                 return 1;
1272         chumins = ru.ru_utime.tv_sec / 60;
1273         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1274         chsmins = ru.ru_stime.tv_sec / 60;
1275         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1276         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1277             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1278         return 0;
1279 }