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  * 4. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #ifndef lint
  34 #if 0
  35 static char sccsid[] = "@(#)eval.c      8.9 (Berkeley) 6/8/95";
  36 #endif
  37 #endif /* not lint */
  38 #include <sys/cdefs.h>
  39 __FBSDID("$FreeBSD$");
  40
  41 #include <paths.h>
  42 #include <signal.h>
  43 #include <stdlib.h>
  44 #include <unistd.h>
  45 #include <sys/resource.h>
  46 #include <sys/wait.h> /* For WIFSIGNALED(status) */
  47 #include <errno.h>
  48
  49 /*
  50  * Evaluate a command.
  51  */
  52
  53 #include "shell.h"
  54 #include "nodes.h"
  55 #include "syntax.h"
  56 #include "expand.h"
  57 #include "parser.h"
  58 #include "jobs.h"
  59 #include "eval.h"
  60 #include "builtins.h"
  61 #include "options.h"
  62 #include "exec.h"
  63 #include "redir.h"
  64 #include "input.h"
  65 #include "output.h"
  66 #include "trap.h"
  67 #include "var.h"
  68 #include "memalloc.h"
  69 #include "error.h"
  70 #include "show.h"
  71 #include "mystring.h"
  72 #ifndef NO_HISTORY
  73 #include "myhistedit.h"
  74 #endif
  75
  76
  77 int evalskip;                   /* set if we are skipping commands */
  78 int skipcount;                  /* number of levels to skip */
  79 static int loopnest;            /* current loop nesting level */
  80 int funcnest;                   /* depth of function calls */
  81 static int builtin_flags;       /* evalcommand flags for builtins */
  82
  83
  84 char *commandname;
  85 struct strlist *cmdenviron;
  86 int exitstatus;                 /* exit status of last command */
  87 int oexitstatus;                /* saved exit status */
  88
  89
  90 static void evalloop(union node *, int);
  91 static void evalfor(union node *, int);
  92 static union node *evalcase(union node *);
  93 static void evalsubshell(union node *, int);
  94 static void evalredir(union node *, int);
  95 static void exphere(union node *, struct arglist *);
  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 void
 108 reseteval(void)
 109 {
 110         evalskip = 0;
 111         loopnest = 0;
 112 }
 113
 114
 115 /*
 116  * The eval command.
 117  */
 118
 119 int
 120 evalcmd(int argc, char **argv)
 121 {
 122         char *p;
 123         char *concat;
 124         char **ap;
 125
 126         if (argc > 1) {
 127                 p = argv[1];
 128                 if (argc > 2) {
 129                         STARTSTACKSTR(concat);
 130                         ap = argv + 2;
 131                         for (;;) {
 132                                 STPUTS(p, concat);
 133                                 if ((p = *ap++) == NULL)
 134                                         break;
 135                                 STPUTC(' ', concat);
 136                         }
 137                         STPUTC('\0', concat);
 138                         p = grabstackstr(concat);
 139                 }
 140                 evalstring(p, builtin_flags);
 141         } else
 142                 exitstatus = 0;
 143         return exitstatus;
 144 }
 145
 146
 147 /*
 148  * Execute a command or commands contained in a string.
 149  */
 150
 151 void
 152 evalstring(char *s, int flags)
 153 {
 154         union node *n;
 155         struct stackmark smark;
 156         int flags_exit;
 157         int any;
 158
 159         flags_exit = flags & EV_EXIT;
 160         flags &= ~EV_EXIT;
 161         any = 0;
 162         setstackmark(&smark);
 163         setinputstring(s, 1);
 164         while ((n = parsecmd(0)) != NEOF) {
 165                 if (n != NULL && !nflag) {
 166                         if (flags_exit && preadateof())
 167                                 evaltree(n, flags | EV_EXIT);
 168                         else
 169                                 evaltree(n, flags);
 170                         any = 1;
 171                 }
 172                 popstackmark(&smark);
 173                 setstackmark(&smark);
 174         }
 175         popfile();
 176         popstackmark(&smark);
 177         if (!any)
 178                 exitstatus = 0;
 179         if (flags_exit)
 180                 exraise(EXEXIT);
 181 }
 182
 183
 184 /*
 185  * Evaluate a parse tree.  The value is left in the global variable
 186  * exitstatus.
 187  */
 188
 189 void
 190 evaltree(union node *n, int flags)
 191 {
 192         int do_etest;
 193         union node *next;
 194         struct stackmark smark;
 195
 196         setstackmark(&smark);
 197         do_etest = 0;
 198         if (n == NULL) {
 199                 TRACE(("evaltree(NULL) called\n"));
 200                 exitstatus = 0;
 201                 goto out;
 202         }
 203         do {
 204                 next = NULL;
 205 #ifndef NO_HISTORY
 206                 displayhist = 1;        /* show history substitutions done with fc */
 207 #endif
 208                 TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
 209                 switch (n->type) {
 210                 case NSEMI:
 211                         evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
 212                         if (evalskip)
 213                                 goto out;
 214                         next = n->nbinary.ch2;
 215                         break;
 216                 case NAND:
 217                         evaltree(n->nbinary.ch1, EV_TESTED);
 218                         if (evalskip || exitstatus != 0) {
 219                                 goto out;
 220                         }
 221                         next = n->nbinary.ch2;
 222                         break;
 223                 case NOR:
 224                         evaltree(n->nbinary.ch1, EV_TESTED);
 225                         if (evalskip || exitstatus == 0)
 226                                 goto out;
 227                         next = n->nbinary.ch2;
 228                         break;
 229                 case NREDIR:
 230                         evalredir(n, flags);
 231                         break;
 232                 case NSUBSHELL:
 233                         evalsubshell(n, flags);
 234                         do_etest = !(flags & EV_TESTED);
 235                         break;
 236                 case NBACKGND:
 237                         evalsubshell(n, flags);
 238                         break;
 239                 case NIF: {
 240                         evaltree(n->nif.test, EV_TESTED);
 241                         if (evalskip)
 242                                 goto out;
 243                         if (exitstatus == 0)
 244                                 next = n->nif.ifpart;
 245                         else if (n->nif.elsepart)
 246                                 next = n->nif.elsepart;
 247                         else
 248                                 exitstatus = 0;
 249                         break;
 250                 }
 251                 case NWHILE:
 252                 case NUNTIL:
 253                         evalloop(n, flags & ~EV_EXIT);
 254                         break;
 255                 case NFOR:
 256                         evalfor(n, flags & ~EV_EXIT);
 257                         break;
 258                 case NCASE:
 259                         next = evalcase(n);
 260                         break;
 261                 case NCLIST:
 262                         next = n->nclist.body;
 263                         break;
 264                 case NCLISTFALLTHRU:
 265                         if (n->nclist.body) {
 266                                 evaltree(n->nclist.body, flags & ~EV_EXIT);
 267                                 if (evalskip)
 268                                         goto out;
 269                         }
 270                         next = n->nclist.next;
 271                         break;
 272                 case NDEFUN:
 273                         defun(n->narg.text, n->narg.next);
 274                         exitstatus = 0;
 275                         break;
 276                 case NNOT:
 277                         evaltree(n->nnot.com, EV_TESTED);
 278                         if (evalskip)
 279                                 goto out;
 280                         exitstatus = !exitstatus;
 281                         break;
 282
 283                 case NPIPE:
 284                         evalpipe(n);
 285                         do_etest = !(flags & EV_TESTED);
 286                         break;
 287                 case NCMD:
 288                         evalcommand(n, flags, (struct backcmd *)NULL);
 289                         do_etest = !(flags & EV_TESTED);
 290                         break;
 291                 default:
 292                         out1fmt("Node type = %d\n", n->type);
 293                         flushout(&output);
 294                         break;
 295                 }
 296                 n = next;
 297                 popstackmark(&smark);
 298                 setstackmark(&smark);
 299         } while (n != NULL);
 300 out:
 301         popstackmark(&smark);
 302         if (pendingsig)
 303                 dotrap();
 304         if (eflag && exitstatus != 0 && do_etest)
 305                 exitshell(exitstatus);
 306         if (flags & EV_EXIT)
 307                 exraise(EXEXIT);
 308 }
 309
 310
 311 static void
 312 evalloop(union node *n, int flags)
 313 {
 314         int status;
 315
 316         loopnest++;
 317         status = 0;
 318         for (;;) {
 319                 if (!evalskip)
 320                         evaltree(n->nbinary.ch1, EV_TESTED);
 321                 if (evalskip) {
 322                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 323                                 evalskip = 0;
 324                                 continue;
 325                         }
 326                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 327                                 evalskip = 0;
 328                         if (evalskip == SKIPRETURN)
 329                                 status = exitstatus;
 330                         break;
 331                 }
 332                 if (n->type == NWHILE) {
 333                         if (exitstatus != 0)
 334                                 break;
 335                 } else {
 336                         if (exitstatus == 0)
 337                                 break;
 338                 }
 339                 evaltree(n->nbinary.ch2, flags);
 340                 status = exitstatus;
 341         }
 342         loopnest--;
 343         exitstatus = status;
 344 }
 345
 346
 347
 348 static void
 349 evalfor(union node *n, int flags)
 350 {
 351         struct arglist arglist;
 352         union node *argp;
 353         struct strlist *sp;
 354         int status;
 355
 356         arglist.lastp = &arglist.list;
 357         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 358                 oexitstatus = exitstatus;
 359                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 360         }
 361         *arglist.lastp = NULL;
 362
 363         loopnest++;
 364         status = 0;
 365         for (sp = arglist.list ; sp ; sp = sp->next) {
 366                 setvar(n->nfor.var, sp->text, 0);
 367                 evaltree(n->nfor.body, flags);
 368                 status = exitstatus;
 369                 if (evalskip) {
 370                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 371                                 evalskip = 0;
 372                                 continue;
 373                         }
 374                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 375                                 evalskip = 0;
 376                         break;
 377                 }
 378         }
 379         loopnest--;
 380         exitstatus = status;
 381 }
 382
 383
 384 /*
 385  * Evaluate a case statement, returning the selected tree.
 386  *
 387  * The exit status needs care to get right.
 388  */
 389
 390 static union node *
 391 evalcase(union node *n)
 392 {
 393         union node *cp;
 394         union node *patp;
 395         struct arglist arglist;
 396
 397         arglist.lastp = &arglist.list;
 398         oexitstatus = exitstatus;
 399         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 400         for (cp = n->ncase.cases ; cp ; cp = cp->nclist.next) {
 401                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 402                         if (casematch(patp, arglist.list->text)) {
 403                                 while (cp->nclist.next &&
 404                                     cp->type == NCLISTFALLTHRU &&
 405                                     cp->nclist.body == NULL)
 406                                         cp = cp->nclist.next;
 407                                 if (cp->nclist.next &&
 408                                     cp->type == NCLISTFALLTHRU)
 409                                         return (cp);
 410                                 if (cp->nclist.body == NULL)
 411                                         exitstatus = 0;
 412                                 return (cp->nclist.body);
 413                         }
 414                 }
 415         }
 416         exitstatus = 0;
 417         return (NULL);
 418 }
 419
 420
 421
 422 /*
 423  * Kick off a subshell to evaluate a tree.
 424  */
 425
 426 static void
 427 evalsubshell(union node *n, int flags)
 428 {
 429         struct job *jp;
 430         int backgnd = (n->type == NBACKGND);
 431
 432         oexitstatus = exitstatus;
 433         expredir(n->nredir.redirect);
 434         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
 435                         forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
 436                 if (backgnd)
 437                         flags &=~ EV_TESTED;
 438                 redirect(n->nredir.redirect, 0);
 439                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 440         } else if (! backgnd) {
 441                 INTOFF;
 442                 exitstatus = waitforjob(jp, (int *)NULL);
 443                 INTON;
 444         } else
 445                 exitstatus = 0;
 446 }
 447
 448
 449 /*
 450  * Evaluate a redirected compound command.
 451  */
 452
 453 static void
 454 evalredir(union node *n, int flags)
 455 {
 456         struct jmploc jmploc;
 457         struct jmploc *savehandler;
 458         volatile int in_redirect = 1;
 459
 460         oexitstatus = exitstatus;
 461         expredir(n->nredir.redirect);
 462         savehandler = handler;
 463         if (setjmp(jmploc.loc)) {
 464                 int e;
 465
 466                 handler = savehandler;
 467                 e = exception;
 468                 popredir();
 469                 if (e == EXERROR || e == EXEXEC) {
 470                         if (in_redirect) {
 471                                 exitstatus = 2;
 472                                 return;
 473                         }
 474                 }
 475                 longjmp(handler->loc, 1);
 476         } else {
 477                 INTOFF;
 478                 handler = &jmploc;
 479                 redirect(n->nredir.redirect, REDIR_PUSH);
 480                 in_redirect = 0;
 481                 INTON;
 482                 evaltree(n->nredir.n, flags);
 483         }
 484         INTOFF;
 485         handler = savehandler;
 486         popredir();
 487         INTON;
 488 }
 489
 490
 491 static void
 492 exphere(union node *redir, struct arglist *fn)
 493 {
 494         struct jmploc jmploc;
 495         struct jmploc *savehandler;
 496         struct localvar *savelocalvars;
 497         int need_longjmp = 0;
 498
 499         redir->nhere.expdoc = nullstr;
 500         savelocalvars = localvars;
 501         localvars = NULL;
 502         forcelocal++;
 503         savehandler = handler;
 504         if (setjmp(jmploc.loc))
 505                 need_longjmp = exception != EXERROR && exception != EXEXEC;
 506         else {
 507                 handler = &jmploc;
 508                 expandarg(redir->nhere.doc, fn, 0);
 509                 redir->nhere.expdoc = fn->list->text;
 510                 INTOFF;
 511         }
 512         handler = savehandler;
 513         forcelocal--;
 514         poplocalvars();
 515         localvars = savelocalvars;
 516         if (need_longjmp)
 517                 longjmp(handler->loc, 1);
 518         INTON;
 519 }
 520
 521
 522 /*
 523  * Compute the names of the files in a redirection list.
 524  */
 525
 526 static void
 527 expredir(union node *n)
 528 {
 529         union node *redir;
 530
 531         for (redir = n ; redir ; redir = redir->nfile.next) {
 532                 struct arglist fn;
 533                 fn.lastp = &fn.list;
 534                 switch (redir->type) {
 535                 case NFROM:
 536                 case NTO:
 537                 case NFROMTO:
 538                 case NAPPEND:
 539                 case NCLOBBER:
 540                         expandarg(redir->nfile.fname, &fn, EXP_TILDE);
 541                         redir->nfile.expfname = fn.list->text;
 542                         break;
 543                 case NFROMFD:
 544                 case NTOFD:
 545                         if (redir->ndup.vname) {
 546                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE);
 547                                 fixredir(redir, fn.list->text, 1);
 548                         }
 549                         break;
 550                 case NXHERE:
 551                         exphere(redir, &fn);
 552                         break;
 553                 }
 554         }
 555 }
 556
 557
 558
 559 /*
 560  * Evaluate a pipeline.  All the processes in the pipeline are children
 561  * of the process creating the pipeline.  (This differs from some versions
 562  * of the shell, which make the last process in a pipeline the parent
 563  * of all the rest.)
 564  */
 565
 566 static void
 567 evalpipe(union node *n)
 568 {
 569         struct job *jp;
 570         struct nodelist *lp;
 571         int pipelen;
 572         int prevfd;
 573         int pip[2];
 574
 575         TRACE(("evalpipe(%p) called\n", (void *)n));
 576         pipelen = 0;
 577         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
 578                 pipelen++;
 579         INTOFF;
 580         jp = makejob(n, pipelen);
 581         prevfd = -1;
 582         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
 583                 prehash(lp->n);
 584                 pip[1] = -1;
 585                 if (lp->next) {
 586                         if (pipe(pip) < 0) {
 587                                 if (prevfd >= 0)
 588                                         close(prevfd);
 589                                 error("Pipe call failed: %s", strerror(errno));
 590                         }
 591                 }
 592                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
 593                         INTON;
 594                         if (prevfd > 0) {
 595                                 dup2(prevfd, 0);
 596                                 close(prevfd);
 597                         }
 598                         if (pip[1] >= 0) {
 599                                 if (!(prevfd >= 0 && pip[0] == 0))
 600                                         close(pip[0]);
 601                                 if (pip[1] != 1) {
 602                                         dup2(pip[1], 1);
 603                                         close(pip[1]);
 604                                 }
 605                         }
 606                         evaltree(lp->n, EV_EXIT);
 607                 }
 608                 if (prevfd >= 0)
 609                         close(prevfd);
 610                 prevfd = pip[0];
 611                 if (pip[1] != -1)
 612                         close(pip[1]);
 613         }
 614         INTON;
 615         if (n->npipe.backgnd == 0) {
 616                 INTOFF;
 617                 exitstatus = waitforjob(jp, (int *)NULL);
 618                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 619                 INTON;
 620         } else
 621                 exitstatus = 0;
 622 }
 623
 624
 625
 626 static int
 627 is_valid_fast_cmdsubst(union node *n)
 628 {
 629
 630         return (n->type == NCMD);
 631 }
 632
 633 /*
 634  * Execute a command inside back quotes.  If it's a builtin command, we
 635  * want to save its output in a block obtained from malloc.  Otherwise
 636  * we fork off a subprocess and get the output of the command via a pipe.
 637  * Should be called with interrupts off.
 638  */
 639
 640 void
 641 evalbackcmd(union node *n, struct backcmd *result)
 642 {
 643         int pip[2];
 644         struct job *jp;
 645         struct stackmark smark;
 646         struct jmploc jmploc;
 647         struct jmploc *savehandler;
 648         struct localvar *savelocalvars;
 649
 650         result->fd = -1;
 651         result->buf = NULL;
 652         result->nleft = 0;
 653         result->jp = NULL;
 654         if (n == NULL) {
 655                 exitstatus = 0;
 656                 return;
 657         }
 658         setstackmark(&smark);
 659         exitstatus = oexitstatus;
 660         if (is_valid_fast_cmdsubst(n)) {
 661                 savelocalvars = localvars;
 662                 localvars = NULL;
 663                 forcelocal++;
 664                 savehandler = handler;
 665                 if (setjmp(jmploc.loc)) {
 666                         if (exception == EXERROR || exception == EXEXEC)
 667                                 exitstatus = 2;
 668                         else if (exception != 0) {
 669                                 handler = savehandler;
 670                                 forcelocal--;
 671                                 poplocalvars();
 672                                 localvars = savelocalvars;
 673                                 longjmp(handler->loc, 1);
 674                         }
 675                 } else {
 676                         handler = &jmploc;
 677                         evalcommand(n, EV_BACKCMD, result);
 678                 }
 679                 handler = savehandler;
 680                 forcelocal--;
 681                 poplocalvars();
 682                 localvars = savelocalvars;
 683         } else {
 684                 if (pipe(pip) < 0)
 685                         error("Pipe call failed: %s", strerror(errno));
 686                 jp = makejob(n, 1);
 687                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 688                         FORCEINTON;
 689                         close(pip[0]);
 690                         if (pip[1] != 1) {
 691                                 dup2(pip[1], 1);
 692                                 close(pip[1]);
 693                         }
 694                         evaltree(n, EV_EXIT);
 695                 }
 696                 close(pip[1]);
 697                 result->fd = pip[0];
 698                 result->jp = jp;
 699         }
 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 static void
 752 xtracecommand(struct arglist *varlist, struct arglist *arglist)
 753 {
 754         struct strlist *sp;
 755         char sep = 0;
 756         const char *p, *ps4;
 757
 758         ps4 = expandstr(ps4val());
 759         out2str(ps4 != NULL ? ps4 : ps4val());
 760         for (sp = varlist->list ; sp ; sp = sp->next) {
 761                 if (sep != 0)
 762                         out2c(' ');
 763                 p = strchr(sp->text, '=');
 764                 if (p != NULL) {
 765                         p++;
 766                         outbin(sp->text, p - sp->text, out2);
 767                         out2qstr(p);
 768                 } else
 769                         out2qstr(sp->text);
 770                 sep = ' ';
 771         }
 772         for (sp = arglist->list ; sp ; sp = sp->next) {
 773                 if (sep != 0)
 774                         out2c(' ');
 775                 /* Disambiguate command looking like assignment. */
 776                 if (sp == arglist->list &&
 777                                 strchr(sp->text, '=') != NULL &&
 778                                 strchr(sp->text, '\'') == NULL) {
 779                         out2c('\'');
 780                         out2str(sp->text);
 781                         out2c('\'');
 782                 } else
 783                         out2qstr(sp->text);
 784                 sep = ' ';
 785         }
 786         out2c('\n');
 787         flushout(&errout);
 788 }
 789
 790 /*
 791  * Check if a builtin can safely be executed in the same process,
 792  * even though it should be in a subshell (command substitution).
 793  * Note that jobid, jobs, times and trap can show information not
 794  * available in a child process; this is deliberate.
 795  * The arguments should already have been expanded.
 796  */
 797 static int
 798 safe_builtin(int idx, int argc, char **argv)
 799 {
 800         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
 801             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
 802             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
 803             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
 804             idx == TYPECMD)
 805                 return (1);
 806         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 807             idx == UMASKCMD)
 808                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 809         if (idx == SETCMD)
 810                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 811                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 812                     argv[1][2] == '\0'));
 813         return (0);
 814 }
 815
 816 /*
 817  * Execute a simple command.
 818  * Note: This may or may not return if (flags & EV_EXIT).
 819  */
 820
 821 static void
 822 evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
 823 {
 824         union node *argp;
 825         struct arglist arglist;
 826         struct arglist varlist;
 827         char **argv;
 828         int argc;
 829         char **envp;
 830         int varflag;
 831         struct strlist *sp;
 832         int mode;
 833         int pip[2];
 834         struct cmdentry cmdentry;
 835         struct job *jp;
 836         struct jmploc jmploc;
 837         struct jmploc *savehandler;
 838         char *savecmdname;
 839         struct shparam saveparam;
 840         struct localvar *savelocalvars;
 841         struct parsefile *savetopfile;
 842         volatile int e;
 843         char *lastarg;
 844         int realstatus;
 845         int do_clearcmdentry;
 846         const char *path = pathval();
 847
 848         /* First expand the arguments. */
 849         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 850         arglist.lastp = &arglist.list;
 851         varlist.lastp = &varlist.list;
 852         varflag = 1;
 853         jp = NULL;
 854         do_clearcmdentry = 0;
 855         oexitstatus = exitstatus;
 856         exitstatus = 0;
 857         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 858                 if (varflag && isassignment(argp->narg.text)) {
 859                         expandarg(argp, varflag == 1 ? &varlist : &arglist,
 860                             EXP_VARTILDE);
 861                         continue;
 862                 } else if (varflag == 1)
 863                         varflag = isdeclarationcmd(&argp->narg) ? 2 : 0;
 864                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 865         }
 866         *arglist.lastp = NULL;
 867         *varlist.lastp = NULL;
 868         expredir(cmd->ncmd.redirect);
 869         argc = 0;
 870         for (sp = arglist.list ; sp ; sp = sp->next)
 871                 argc++;
 872         /* Add one slot at the beginning for tryexec(). */
 873         argv = stalloc(sizeof (char *) * (argc + 2));
 874         argv++;
 875
 876         for (sp = arglist.list ; sp ; sp = sp->next) {
 877                 TRACE(("evalcommand arg: %s\n", sp->text));
 878                 *argv++ = sp->text;
 879         }
 880         *argv = NULL;
 881         lastarg = NULL;
 882         if (iflag && funcnest == 0 && argc > 0)
 883                 lastarg = argv[-1];
 884         argv -= argc;
 885
 886         /* Print the command if xflag is set. */
 887         if (xflag)
 888                 xtracecommand(&varlist, &arglist);
 889
 890         /* Now locate the command. */
 891         if (argc == 0) {
 892                 /* Variable assignment(s) without command */
 893                 cmdentry.cmdtype = CMDBUILTIN;
 894                 cmdentry.u.index = BLTINCMD;
 895                 cmdentry.special = 0;
 896         } else {
 897                 static const char PATH[] = "PATH=";
 898                 int cmd_flags = 0, bltinonly = 0;
 899
 900                 /*
 901                  * Modify the command lookup path, if a PATH= assignment
 902                  * is present
 903                  */
 904                 for (sp = varlist.list ; sp ; sp = sp->next)
 905                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 906                                 path = sp->text + sizeof(PATH) - 1;
 907                                 /*
 908                                  * On `PATH=... command`, we need to make
 909                                  * sure that the command isn't using the
 910                                  * non-updated hash table of the outer PATH
 911                                  * setting and we need to make sure that
 912                                  * the hash table isn't filled with items
 913                                  * from the temporary setting.
 914                                  *
 915                                  * It would be better to forbit using and
 916                                  * updating the table while this command
 917                                  * runs, by the command finding mechanism
 918                                  * is heavily integrated with hash handling,
 919                                  * so we just delete the hash before and after
 920                                  * the command runs. Partly deleting like
 921                                  * changepatch() does doesn't seem worth the
 922                                  * bookinging effort, since most such runs add
 923                                  * directories in front of the new PATH.
 924                                  */
 925                                 clearcmdentry();
 926                                 do_clearcmdentry = 1;
 927                         }
 928
 929                 for (;;) {
 930                         if (bltinonly) {
 931                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 932                                 if (cmdentry.u.index < 0) {
 933                                         cmdentry.u.index = BLTINCMD;
 934                                         argv--;
 935                                         argc++;
 936                                         break;
 937                                 }
 938                         } else
 939                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 940                         /* implement the bltin and command builtins here */
 941                         if (cmdentry.cmdtype != CMDBUILTIN)
 942                                 break;
 943                         if (cmdentry.u.index == BLTINCMD) {
 944                                 if (argc == 1)
 945                                         break;
 946                                 argv++;
 947                                 argc--;
 948                                 bltinonly = 1;
 949                         } else if (cmdentry.u.index == COMMANDCMD) {
 950                                 if (argc == 1)
 951                                         break;
 952                                 if (!strcmp(argv[1], "-p")) {
 953                                         if (argc == 2)
 954                                                 break;
 955                                         if (argv[2][0] == '-') {
 956                                                 if (strcmp(argv[2], "--"))
 957                                                         break;
 958                                                 if (argc == 3)
 959                                                         break;
 960                                                 argv += 3;
 961                                                 argc -= 3;
 962                                         } else {
 963                                                 argv += 2;
 964                                                 argc -= 2;
 965                                         }
 966                                         path = _PATH_STDPATH;
 967                                         clearcmdentry();
 968                                         do_clearcmdentry = 1;
 969                                 } else if (!strcmp(argv[1], "--")) {
 970                                         if (argc == 2)
 971                                                 break;
 972                                         argv += 2;
 973                                         argc -= 2;
 974                                 } else if (argv[1][0] == '-')
 975                                         break;
 976                                 else {
 977                                         argv++;
 978                                         argc--;
 979                                 }
 980                                 cmd_flags |= DO_NOFUNC;
 981                                 bltinonly = 0;
 982                         } else
 983                                 break;
 984                 }
 985                 /*
 986                  * Special builtins lose their special properties when
 987                  * called via 'command'.
 988                  */
 989                 if (cmd_flags & DO_NOFUNC)
 990                         cmdentry.special = 0;
 991         }
 992
 993         /* Fork off a child process if necessary. */
 994         if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 995             && ((flags & EV_EXIT) == 0 || have_traps()))
 996          || ((flags & EV_BACKCMD) != 0
 997             && (cmdentry.cmdtype != CMDBUILTIN ||
 998                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 999                 jp = makejob(cmd, 1);
1000                 mode = FORK_FG;
1001                 if (flags & EV_BACKCMD) {
1002                         mode = FORK_NOJOB;
1003                         if (pipe(pip) < 0)
1004                                 error("Pipe call failed: %s", strerror(errno));
1005                 }
1006                 if (cmdentry.cmdtype == CMDNORMAL &&
1007                     cmd->ncmd.redirect == NULL &&
1008                     varlist.list == NULL &&
1009                     (mode == FORK_FG || mode == FORK_NOJOB) &&
1010                     !disvforkset() && !iflag && !mflag) {
1011                         vforkexecshell(jp, argv, environment(), path,
1012                             cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL);
1013                         goto parent;
1014                 }
1015                 if (forkshell(jp, cmd, mode) != 0)
1016                         goto parent;    /* at end of routine */
1017                 if (flags & EV_BACKCMD) {
1018                         FORCEINTON;
1019                         close(pip[0]);
1020                         if (pip[1] != 1) {
1021                                 dup2(pip[1], 1);
1022                                 close(pip[1]);
1023                         }
1024                         flags &= ~EV_BACKCMD;
1025                 }
1026                 flags |= EV_EXIT;
1027         }
1028
1029         /* This is the child process if a fork occurred. */
1030         /* Execute the command. */
1031         if (cmdentry.cmdtype == CMDFUNCTION) {
1032 #ifdef DEBUG
1033                 trputs("Shell function:  ");  trargs(argv);
1034 #endif
1035                 saveparam = shellparam;
1036                 shellparam.malloc = 0;
1037                 shellparam.reset = 1;
1038                 shellparam.nparam = argc - 1;
1039                 shellparam.p = argv + 1;
1040                 shellparam.optnext = NULL;
1041                 INTOFF;
1042                 savelocalvars = localvars;
1043                 localvars = NULL;
1044                 reffunc(cmdentry.u.func);
1045                 savehandler = handler;
1046                 if (setjmp(jmploc.loc)) {
1047                         freeparam(&shellparam);
1048                         shellparam = saveparam;
1049                         popredir();
1050                         unreffunc(cmdentry.u.func);
1051                         poplocalvars();
1052                         localvars = savelocalvars;
1053                         funcnest--;
1054                         handler = savehandler;
1055                         longjmp(handler->loc, 1);
1056                 }
1057                 handler = &jmploc;
1058                 funcnest++;
1059                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
1060                 INTON;
1061                 for (sp = varlist.list ; sp ; sp = sp->next)
1062                         mklocal(sp->text);
1063                 exitstatus = oexitstatus;
1064                 evaltree(getfuncnode(cmdentry.u.func),
1065                     flags & (EV_TESTED | EV_EXIT));
1066                 INTOFF;
1067                 unreffunc(cmdentry.u.func);
1068                 poplocalvars();
1069                 localvars = savelocalvars;
1070                 freeparam(&shellparam);
1071                 shellparam = saveparam;
1072                 handler = savehandler;
1073                 funcnest--;
1074                 popredir();
1075                 INTON;
1076                 if (evalskip == SKIPRETURN) {
1077                         evalskip = 0;
1078                         skipcount = 0;
1079                 }
1080                 if (jp)
1081                         exitshell(exitstatus);
1082         } else if (cmdentry.cmdtype == CMDBUILTIN) {
1083 #ifdef DEBUG
1084                 trputs("builtin command:  ");  trargs(argv);
1085 #endif
1086                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
1087                 if (flags == EV_BACKCMD) {
1088                         memout.nleft = 0;
1089                         memout.nextc = memout.buf;
1090                         memout.bufsize = 64;
1091                         mode |= REDIR_BACKQ;
1092                 }
1093                 savecmdname = commandname;
1094                 savetopfile = getcurrentfile();
1095                 cmdenviron = varlist.list;
1096                 e = -1;
1097                 savehandler = handler;
1098                 if (setjmp(jmploc.loc)) {
1099                         e = exception;
1100                         if (e == EXINT)
1101                                 exitstatus = SIGINT+128;
1102                         else if (e != EXEXIT)
1103                                 exitstatus = 2;
1104                         goto cmddone;
1105                 }
1106                 handler = &jmploc;
1107                 redirect(cmd->ncmd.redirect, mode);
1108                 outclearerror(out1);
1109                 /*
1110                  * If there is no command word, redirection errors should
1111                  * not be fatal but assignment errors should.
1112                  */
1113                 if (argc == 0)
1114                         cmdentry.special = 1;
1115                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1116                 if (argc > 0)
1117                         bltinsetlocale();
1118                 commandname = argv[0];
1119                 argptr = argv + 1;
1120                 nextopt_optptr = NULL;          /* initialize nextopt */
1121                 builtin_flags = flags;
1122                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1123                 flushall();
1124                 if (outiserror(out1)) {
1125                         warning("write error on stdout");
1126                         if (exitstatus == 0 || exitstatus == 1)
1127                                 exitstatus = 2;
1128                 }
1129 cmddone:
1130                 if (argc > 0)
1131                         bltinunsetlocale();
1132                 cmdenviron = NULL;
1133                 out1 = &output;
1134                 out2 = &errout;
1135                 freestdout();
1136                 handler = savehandler;
1137                 commandname = savecmdname;
1138                 if (jp)
1139                         exitshell(exitstatus);
1140                 if (flags == EV_BACKCMD) {
1141                         backcmd->buf = memout.buf;
1142                         backcmd->nleft = memout.nextc - memout.buf;
1143                         memout.buf = NULL;
1144                 }
1145                 if (cmdentry.u.index != EXECCMD)
1146                         popredir();
1147                 if (e != -1) {
1148                         if ((e != EXERROR && e != EXEXEC)
1149                             || cmdentry.special)
1150                                 exraise(e);
1151                         popfilesupto(savetopfile);
1152                         if (flags != EV_BACKCMD)
1153                                 FORCEINTON;
1154                 }
1155         } else {
1156 #ifdef DEBUG
1157                 trputs("normal command:  ");  trargs(argv);
1158 #endif
1159                 redirect(cmd->ncmd.redirect, 0);
1160                 for (sp = varlist.list ; sp ; sp = sp->next)
1161                         setvareq(sp->text, VEXPORT|VSTACK);
1162                 envp = environment();
1163                 shellexec(argv, envp, path, cmdentry.u.index);
1164                 /*NOTREACHED*/
1165         }
1166         goto out;
1167
1168 parent: /* parent process gets here (if we forked) */
1169         if (mode == FORK_FG) {  /* argument to fork */
1170                 INTOFF;
1171                 exitstatus = waitforjob(jp, &realstatus);
1172                 INTON;
1173                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1174                         evalskip = SKIPBREAK;
1175                         skipcount = loopnest;
1176                 }
1177         } else if (mode == FORK_NOJOB) {
1178                 backcmd->fd = pip[0];
1179                 close(pip[1]);
1180                 backcmd->jp = jp;
1181         }
1182
1183 out:
1184         if (lastarg)
1185                 setvar("_", lastarg, 0);
1186         if (do_clearcmdentry)
1187                 clearcmdentry();
1188 }
1189
1190
1191
1192 /*
1193  * Search for a command.  This is called before we fork so that the
1194  * location of the command will be available in the parent as well as
1195  * the child.  The check for "goodname" is an overly conservative
1196  * check that the name will not be subject to expansion.
1197  */
1198
1199 static void
1200 prehash(union node *n)
1201 {
1202         struct cmdentry entry;
1203
1204         if (n && n->type == NCMD && n->ncmd.args)
1205                 if (goodname(n->ncmd.args->narg.text))
1206                         find_command(n->ncmd.args->narg.text, &entry, 0,
1207                                      pathval());
1208 }
1209
1210
1211
1212 /*
1213  * Builtin commands.  Builtin commands whose functions are closely
1214  * tied to evaluation are implemented here.
1215  */
1216
1217 /*
1218  * No command given, a bltin command with no arguments, or a bltin command
1219  * with an invalid name.
1220  */
1221
1222 int
1223 bltincmd(int argc, char **argv)
1224 {
1225         if (argc > 1) {
1226                 out2fmt_flush("%s: not found\n", argv[1]);
1227                 return 127;
1228         }
1229         /*
1230          * Preserve exitstatus of a previous possible redirection
1231          * as POSIX mandates
1232          */
1233         return exitstatus;
1234 }
1235
1236
1237 /*
1238  * Handle break and continue commands.  Break, continue, and return are
1239  * all handled by setting the evalskip flag.  The evaluation routines
1240  * above all check this flag, and if it is set they start skipping
1241  * commands rather than executing them.  The variable skipcount is
1242  * the number of loops to break/continue, or the number of function
1243  * levels to return.  (The latter is always 1.)  It should probably
1244  * be an error to break out of more loops than exist, but it isn't
1245  * in the standard shell so we don't make it one here.
1246  */
1247
1248 int
1249 breakcmd(int argc, char **argv)
1250 {
1251         int n = argc > 1 ? number(argv[1]) : 1;
1252
1253         if (n > loopnest)
1254                 n = loopnest;
1255         if (n > 0) {
1256                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1257                 skipcount = n;
1258         }
1259         return 0;
1260 }
1261
1262 /*
1263  * The `command' command.
1264  */
1265 int
1266 commandcmd(int argc __unused, char **argv __unused)
1267 {
1268         const char *path;
1269         int ch;
1270         int cmd = -1;
1271
1272         path = bltinlookup("PATH", 1);
1273
1274         while ((ch = nextopt("pvV")) != '\0') {
1275                 switch (ch) {
1276                 case 'p':
1277                         path = _PATH_STDPATH;
1278                         break;
1279                 case 'v':
1280                         cmd = TYPECMD_SMALLV;
1281                         break;
1282                 case 'V':
1283                         cmd = TYPECMD_BIGV;
1284                         break;
1285                 }
1286         }
1287
1288         if (cmd != -1) {
1289                 if (*argptr == NULL || argptr[1] != NULL)
1290                         error("wrong number of arguments");
1291                 return typecmd_impl(2, argptr - 1, cmd, path);
1292         }
1293         if (*argptr != NULL)
1294                 error("commandcmd bad call");
1295
1296         /*
1297          * Do nothing successfully if no command was specified;
1298          * ksh also does this.
1299          */
1300         return 0;
1301 }
1302
1303
1304 /*
1305  * The return command.
1306  */
1307
1308 int
1309 returncmd(int argc, char **argv)
1310 {
1311         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1312
1313         evalskip = SKIPRETURN;
1314         skipcount = 1;
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 }