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                 evaltree(n->nbinary.ch1, EV_TESTED);
 320                 if (evalskip) {
 321 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
 322                                 evalskip = 0;
 323                                 continue;
 324                         }
 325                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 326                                 evalskip = 0;
 327                         if (evalskip == SKIPRETURN)
 328                                 status = exitstatus;
 329                         break;
 330                 }
 331                 if (n->type == NWHILE) {
 332                         if (exitstatus != 0)
 333                                 break;
 334                 } else {
 335                         if (exitstatus == 0)
 336                                 break;
 337                 }
 338                 evaltree(n->nbinary.ch2, flags);
 339                 status = exitstatus;
 340                 if (evalskip)
 341                         goto skipping;
 342         }
 343         loopnest--;
 344         exitstatus = status;
 345 }
 346
 347
 348
 349 static void
 350 evalfor(union node *n, int flags)
 351 {
 352         struct arglist arglist;
 353         union node *argp;
 354         struct strlist *sp;
 355         int status;
 356
 357         arglist.lastp = &arglist.list;
 358         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
 359                 oexitstatus = exitstatus;
 360                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 361         }
 362         *arglist.lastp = NULL;
 363
 364         loopnest++;
 365         status = 0;
 366         for (sp = arglist.list ; sp ; sp = sp->next) {
 367                 setvar(n->nfor.var, sp->text, 0);
 368                 evaltree(n->nfor.body, flags);
 369                 status = exitstatus;
 370                 if (evalskip) {
 371                         if (evalskip == SKIPCONT && --skipcount <= 0) {
 372                                 evalskip = 0;
 373                                 continue;
 374                         }
 375                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 376                                 evalskip = 0;
 377                         break;
 378                 }
 379         }
 380         loopnest--;
 381         exitstatus = status;
 382 }
 383
 384
 385 /*
 386  * Evaluate a case statement, returning the selected tree.
 387  *
 388  * The exit status needs care to get right.
 389  */
 390
 391 static union node *
 392 evalcase(union node *n)
 393 {
 394         union node *cp;
 395         union node *patp;
 396         struct arglist arglist;
 397
 398         arglist.lastp = &arglist.list;
 399         oexitstatus = exitstatus;
 400         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
 401         for (cp = n->ncase.cases ; cp ; cp = cp->nclist.next) {
 402                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
 403                         if (casematch(patp, arglist.list->text)) {
 404                                 while (cp->nclist.next &&
 405                                     cp->type == NCLISTFALLTHRU &&
 406                                     cp->nclist.body == NULL)
 407                                         cp = cp->nclist.next;
 408                                 if (cp->nclist.next &&
 409                                     cp->type == NCLISTFALLTHRU)
 410                                         return (cp);
 411                                 if (cp->nclist.body == NULL)
 412                                         exitstatus = 0;
 413                                 return (cp->nclist.body);
 414                         }
 415                 }
 416         }
 417         exitstatus = 0;
 418         return (NULL);
 419 }
 420
 421
 422
 423 /*
 424  * Kick off a subshell to evaluate a tree.
 425  */
 426
 427 static void
 428 evalsubshell(union node *n, int flags)
 429 {
 430         struct job *jp;
 431         int backgnd = (n->type == NBACKGND);
 432
 433         oexitstatus = exitstatus;
 434         expredir(n->nredir.redirect);
 435         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
 436                         forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
 437                 if (backgnd)
 438                         flags &=~ EV_TESTED;
 439                 redirect(n->nredir.redirect, 0);
 440                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
 441         } else if (! backgnd) {
 442                 INTOFF;
 443                 exitstatus = waitforjob(jp, (int *)NULL);
 444                 INTON;
 445         } else
 446                 exitstatus = 0;
 447 }
 448
 449
 450 /*
 451  * Evaluate a redirected compound command.
 452  */
 453
 454 static void
 455 evalredir(union node *n, int flags)
 456 {
 457         struct jmploc jmploc;
 458         struct jmploc *savehandler;
 459         volatile int in_redirect = 1;
 460
 461         oexitstatus = exitstatus;
 462         expredir(n->nredir.redirect);
 463         savehandler = handler;
 464         if (setjmp(jmploc.loc)) {
 465                 int e;
 466
 467                 handler = savehandler;
 468                 e = exception;
 469                 popredir();
 470                 if (e == EXERROR || e == EXEXEC) {
 471                         if (in_redirect) {
 472                                 exitstatus = 2;
 473                                 return;
 474                         }
 475                 }
 476                 longjmp(handler->loc, 1);
 477         } else {
 478                 INTOFF;
 479                 handler = &jmploc;
 480                 redirect(n->nredir.redirect, REDIR_PUSH);
 481                 in_redirect = 0;
 482                 INTON;
 483                 evaltree(n->nredir.n, flags);
 484         }
 485         INTOFF;
 486         handler = savehandler;
 487         popredir();
 488         INTON;
 489 }
 490
 491
 492 static void
 493 exphere(union node *redir, struct arglist *fn)
 494 {
 495         struct jmploc jmploc;
 496         struct jmploc *savehandler;
 497         struct localvar *savelocalvars;
 498         int need_longjmp = 0;
 499
 500         redir->nhere.expdoc = nullstr;
 501         savelocalvars = localvars;
 502         localvars = NULL;
 503         forcelocal++;
 504         savehandler = handler;
 505         if (setjmp(jmploc.loc))
 506                 need_longjmp = exception != EXERROR && exception != EXEXEC;
 507         else {
 508                 handler = &jmploc;
 509                 expandarg(redir->nhere.doc, fn, 0);
 510                 redir->nhere.expdoc = fn->list->text;
 511                 INTOFF;
 512         }
 513         handler = savehandler;
 514         forcelocal--;
 515         poplocalvars();
 516         localvars = savelocalvars;
 517         if (need_longjmp)
 518                 longjmp(handler->loc, 1);
 519         INTON;
 520 }
 521
 522
 523 /*
 524  * Compute the names of the files in a redirection list.
 525  */
 526
 527 static void
 528 expredir(union node *n)
 529 {
 530         union node *redir;
 531
 532         for (redir = n ; redir ; redir = redir->nfile.next) {
 533                 struct arglist fn;
 534                 fn.lastp = &fn.list;
 535                 switch (redir->type) {
 536                 case NFROM:
 537                 case NTO:
 538                 case NFROMTO:
 539                 case NAPPEND:
 540                 case NCLOBBER:
 541                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 542                         redir->nfile.expfname = fn.list->text;
 543                         break;
 544                 case NFROMFD:
 545                 case NTOFD:
 546                         if (redir->ndup.vname) {
 547                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
 548                                 fixredir(redir, fn.list->text, 1);
 549                         }
 550                         break;
 551                 case NXHERE:
 552                         exphere(redir, &fn);
 553                         break;
 554                 }
 555         }
 556 }
 557
 558
 559
 560 /*
 561  * Evaluate a pipeline.  All the processes in the pipeline are children
 562  * of the process creating the pipeline.  (This differs from some versions
 563  * of the shell, which make the last process in a pipeline the parent
 564  * of all the rest.)
 565  */
 566
 567 static void
 568 evalpipe(union node *n)
 569 {
 570         struct job *jp;
 571         struct nodelist *lp;
 572         int pipelen;
 573         int prevfd;
 574         int pip[2];
 575
 576         TRACE(("evalpipe(%p) called\n", (void *)n));
 577         pipelen = 0;
 578         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
 579                 pipelen++;
 580         INTOFF;
 581         jp = makejob(n, pipelen);
 582         prevfd = -1;
 583         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
 584                 prehash(lp->n);
 585                 pip[1] = -1;
 586                 if (lp->next) {
 587                         if (pipe(pip) < 0) {
 588                                 if (prevfd >= 0)
 589                                         close(prevfd);
 590                                 error("Pipe call failed: %s", strerror(errno));
 591                         }
 592                 }
 593                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
 594                         INTON;
 595                         if (prevfd > 0) {
 596                                 dup2(prevfd, 0);
 597                                 close(prevfd);
 598                         }
 599                         if (pip[1] >= 0) {
 600                                 if (!(prevfd >= 0 && pip[0] == 0))
 601                                         close(pip[0]);
 602                                 if (pip[1] != 1) {
 603                                         dup2(pip[1], 1);
 604                                         close(pip[1]);
 605                                 }
 606                         }
 607                         evaltree(lp->n, EV_EXIT);
 608                 }
 609                 if (prevfd >= 0)
 610                         close(prevfd);
 611                 prevfd = pip[0];
 612                 if (pip[1] != -1)
 613                         close(pip[1]);
 614         }
 615         INTON;
 616         if (n->npipe.backgnd == 0) {
 617                 INTOFF;
 618                 exitstatus = waitforjob(jp, (int *)NULL);
 619                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
 620                 INTON;
 621         } else
 622                 exitstatus = 0;
 623 }
 624
 625
 626
 627 static int
 628 is_valid_fast_cmdsubst(union node *n)
 629 {
 630
 631         return (n->type == NCMD);
 632 }
 633
 634 /*
 635  * Execute a command inside back quotes.  If it's a builtin command, we
 636  * want to save its output in a block obtained from malloc.  Otherwise
 637  * we fork off a subprocess and get the output of the command via a pipe.
 638  * Should be called with interrupts off.
 639  */
 640
 641 void
 642 evalbackcmd(union node *n, struct backcmd *result)
 643 {
 644         int pip[2];
 645         struct job *jp;
 646         struct stackmark smark;
 647         struct jmploc jmploc;
 648         struct jmploc *savehandler;
 649         struct localvar *savelocalvars;
 650
 651         setstackmark(&smark);
 652         result->fd = -1;
 653         result->buf = NULL;
 654         result->nleft = 0;
 655         result->jp = NULL;
 656         if (n == NULL) {
 657                 exitstatus = 0;
 658                 goto out;
 659         }
 660         exitstatus = oexitstatus;
 661         if (is_valid_fast_cmdsubst(n)) {
 662                 savelocalvars = localvars;
 663                 localvars = NULL;
 664                 forcelocal++;
 665                 savehandler = handler;
 666                 if (setjmp(jmploc.loc)) {
 667                         if (exception == EXERROR || exception == EXEXEC)
 668                                 exitstatus = 2;
 669                         else if (exception != 0) {
 670                                 handler = savehandler;
 671                                 forcelocal--;
 672                                 poplocalvars();
 673                                 localvars = savelocalvars;
 674                                 longjmp(handler->loc, 1);
 675                         }
 676                 } else {
 677                         handler = &jmploc;
 678                         evalcommand(n, EV_BACKCMD, result);
 679                 }
 680                 handler = savehandler;
 681                 forcelocal--;
 682                 poplocalvars();
 683                 localvars = savelocalvars;
 684         } else {
 685                 if (pipe(pip) < 0)
 686                         error("Pipe call failed: %s", strerror(errno));
 687                 jp = makejob(n, 1);
 688                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
 689                         FORCEINTON;
 690                         close(pip[0]);
 691                         if (pip[1] != 1) {
 692                                 dup2(pip[1], 1);
 693                                 close(pip[1]);
 694                         }
 695                         evaltree(n, EV_EXIT);
 696                 }
 697                 close(pip[1]);
 698                 result->fd = pip[0];
 699                 result->jp = jp;
 700         }
 701 out:
 702         popstackmark(&smark);
 703         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 704                 result->fd, result->buf, result->nleft, result->jp));
 705 }
 706
 707 static int
 708 mustexpandto(const char *argtext, const char *mask)
 709 {
 710         for (;;) {
 711                 if (*argtext == CTLQUOTEMARK || *argtext == CTLQUOTEEND) {
 712                         argtext++;
 713                         continue;
 714                 }
 715                 if (*argtext == CTLESC)
 716                         argtext++;
 717                 else if (BASESYNTAX[(int)*argtext] == CCTL)
 718                         return (0);
 719                 if (*argtext != *mask)
 720                         return (0);
 721                 if (*argtext == '\0')
 722                         return (1);
 723                 argtext++;
 724                 mask++;
 725         }
 726 }
 727
 728 static int
 729 isdeclarationcmd(struct narg *arg)
 730 {
 731         int have_command = 0;
 732
 733         if (arg == NULL)
 734                 return (0);
 735         while (mustexpandto(arg->text, "command")) {
 736                 have_command = 1;
 737                 arg = &arg->next->narg;
 738                 if (arg == NULL)
 739                         return (0);
 740                 /*
 741                  * To also allow "command -p" and "command --" as part of
 742                  * a declaration command, add code here.
 743                  * We do not do this, as ksh does not do it either and it
 744                  * is not required by POSIX.
 745                  */
 746         }
 747         return (mustexpandto(arg->text, "export") ||
 748             mustexpandto(arg->text, "readonly") ||
 749             (mustexpandto(arg->text, "local") &&
 750                 (have_command || !isfunc("local"))));
 751 }
 752
 753 /*
 754  * Check if a builtin can safely be executed in the same process,
 755  * even though it should be in a subshell (command substitution).
 756  * Note that jobid, jobs, times and trap can show information not
 757  * available in a child process; this is deliberate.
 758  * The arguments should already have been expanded.
 759  */
 760 static int
 761 safe_builtin(int idx, int argc, char **argv)
 762 {
 763         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
 764             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
 765             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
 766             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
 767             idx == TYPECMD)
 768                 return (1);
 769         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 770             idx == UMASKCMD)
 771                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 772         if (idx == SETCMD)
 773                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 774                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 775                     argv[1][2] == '\0'));
 776         return (0);
 777 }
 778
 779 /*
 780  * Execute a simple command.
 781  * Note: This may or may not return if (flags & EV_EXIT).
 782  */
 783
 784 static void
 785 evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
 786 {
 787         union node *argp;
 788         struct arglist arglist;
 789         struct arglist varlist;
 790         char **argv;
 791         int argc;
 792         char **envp;
 793         int varflag;
 794         struct strlist *sp;
 795         int mode;
 796         int pip[2];
 797         struct cmdentry cmdentry;
 798         struct job *jp;
 799         struct jmploc jmploc;
 800         struct jmploc *savehandler;
 801         char *savecmdname;
 802         struct shparam saveparam;
 803         struct localvar *savelocalvars;
 804         struct parsefile *savetopfile;
 805         volatile int e;
 806         char *lastarg;
 807         int realstatus;
 808         int do_clearcmdentry;
 809         const char *path = pathval();
 810
 811         /* First expand the arguments. */
 812         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
 813         arglist.lastp = &arglist.list;
 814         varlist.lastp = &varlist.list;
 815         varflag = 1;
 816         jp = NULL;
 817         do_clearcmdentry = 0;
 818         oexitstatus = exitstatus;
 819         exitstatus = 0;
 820         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
 821                 if (varflag && isassignment(argp->narg.text)) {
 822                         expandarg(argp, varflag == 1 ? &varlist : &arglist,
 823                             EXP_VARTILDE);
 824                         continue;
 825                 } else if (varflag == 1)
 826                         varflag = isdeclarationcmd(&argp->narg) ? 2 : 0;
 827                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
 828         }
 829         *arglist.lastp = NULL;
 830         *varlist.lastp = NULL;
 831         expredir(cmd->ncmd.redirect);
 832         argc = 0;
 833         for (sp = arglist.list ; sp ; sp = sp->next)
 834                 argc++;
 835         /* Add one slot at the beginning for tryexec(). */
 836         argv = stalloc(sizeof (char *) * (argc + 2));
 837         argv++;
 838
 839         for (sp = arglist.list ; sp ; sp = sp->next) {
 840                 TRACE(("evalcommand arg: %s\n", sp->text));
 841                 *argv++ = sp->text;
 842         }
 843         *argv = NULL;
 844         lastarg = NULL;
 845         if (iflag && funcnest == 0 && argc > 0)
 846                 lastarg = argv[-1];
 847         argv -= argc;
 848
 849         /* Print the command if xflag is set. */
 850         if (xflag) {
 851                 char sep = 0;
 852                 const char *p, *ps4;
 853                 ps4 = expandstr(ps4val());
 854                 out2str(ps4 != NULL ? ps4 : ps4val());
 855                 for (sp = varlist.list ; sp ; sp = sp->next) {
 856                         if (sep != 0)
 857                                 out2c(' ');
 858                         p = strchr(sp->text, '=');
 859                         if (p != NULL) {
 860                                 p++;
 861                                 outbin(sp->text, p - sp->text, out2);
 862                                 out2qstr(p);
 863                         } else
 864                                 out2qstr(sp->text);
 865                         sep = ' ';
 866                 }
 867                 for (sp = arglist.list ; sp ; sp = sp->next) {
 868                         if (sep != 0)
 869                                 out2c(' ');
 870                         /* Disambiguate command looking like assignment. */
 871                         if (sp == arglist.list &&
 872                                         strchr(sp->text, '=') != NULL &&
 873                                         strchr(sp->text, '\'') == NULL) {
 874                                 out2c('\'');
 875                                 out2str(sp->text);
 876                                 out2c('\'');
 877                         } else
 878                                 out2qstr(sp->text);
 879                         sep = ' ';
 880                 }
 881                 out2c('\n');
 882                 flushout(&errout);
 883         }
 884
 885         /* Now locate the command. */
 886         if (argc == 0) {
 887                 /* Variable assignment(s) without command */
 888                 cmdentry.cmdtype = CMDBUILTIN;
 889                 cmdentry.u.index = BLTINCMD;
 890                 cmdentry.special = 0;
 891         } else {
 892                 static const char PATH[] = "PATH=";
 893                 int cmd_flags = 0, bltinonly = 0;
 894
 895                 /*
 896                  * Modify the command lookup path, if a PATH= assignment
 897                  * is present
 898                  */
 899                 for (sp = varlist.list ; sp ; sp = sp->next)
 900                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
 901                                 path = sp->text + sizeof(PATH) - 1;
 902                                 /*
 903                                  * On `PATH=... command`, we need to make
 904                                  * sure that the command isn't using the
 905                                  * non-updated hash table of the outer PATH
 906                                  * setting and we need to make sure that
 907                                  * the hash table isn't filled with items
 908                                  * from the temporary setting.
 909                                  *
 910                                  * It would be better to forbit using and
 911                                  * updating the table while this command
 912                                  * runs, by the command finding mechanism
 913                                  * is heavily integrated with hash handling,
 914                                  * so we just delete the hash before and after
 915                                  * the command runs. Partly deleting like
 916                                  * changepatch() does doesn't seem worth the
 917                                  * bookinging effort, since most such runs add
 918                                  * directories in front of the new PATH.
 919                                  */
 920                                 clearcmdentry();
 921                                 do_clearcmdentry = 1;
 922                         }
 923
 924                 for (;;) {
 925                         if (bltinonly) {
 926                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
 927                                 if (cmdentry.u.index < 0) {
 928                                         cmdentry.u.index = BLTINCMD;
 929                                         argv--;
 930                                         argc++;
 931                                         break;
 932                                 }
 933                         } else
 934                                 find_command(argv[0], &cmdentry, cmd_flags, path);
 935                         /* implement the bltin and command builtins here */
 936                         if (cmdentry.cmdtype != CMDBUILTIN)
 937                                 break;
 938                         if (cmdentry.u.index == BLTINCMD) {
 939                                 if (argc == 1)
 940                                         break;
 941                                 argv++;
 942                                 argc--;
 943                                 bltinonly = 1;
 944                         } else if (cmdentry.u.index == COMMANDCMD) {
 945                                 if (argc == 1)
 946                                         break;
 947                                 if (!strcmp(argv[1], "-p")) {
 948                                         if (argc == 2)
 949                                                 break;
 950                                         if (argv[2][0] == '-') {
 951                                                 if (strcmp(argv[2], "--"))
 952                                                         break;
 953                                                 if (argc == 3)
 954                                                         break;
 955                                                 argv += 3;
 956                                                 argc -= 3;
 957                                         } else {
 958                                                 argv += 2;
 959                                                 argc -= 2;
 960                                         }
 961                                         path = _PATH_STDPATH;
 962                                         clearcmdentry();
 963                                         do_clearcmdentry = 1;
 964                                 } else if (!strcmp(argv[1], "--")) {
 965                                         if (argc == 2)
 966                                                 break;
 967                                         argv += 2;
 968                                         argc -= 2;
 969                                 } else if (argv[1][0] == '-')
 970                                         break;
 971                                 else {
 972                                         argv++;
 973                                         argc--;
 974                                 }
 975                                 cmd_flags |= DO_NOFUNC;
 976                                 bltinonly = 0;
 977                         } else
 978                                 break;
 979                 }
 980                 /*
 981                  * Special builtins lose their special properties when
 982                  * called via 'command'.
 983                  */
 984                 if (cmd_flags & DO_NOFUNC)
 985                         cmdentry.special = 0;
 986         }
 987
 988         /* Fork off a child process if necessary. */
 989         if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
 990             && ((flags & EV_EXIT) == 0 || have_traps()))
 991          || ((flags & EV_BACKCMD) != 0
 992             && (cmdentry.cmdtype != CMDBUILTIN ||
 993                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
 994                 jp = makejob(cmd, 1);
 995                 mode = FORK_FG;
 996                 if (flags & EV_BACKCMD) {
 997                         mode = FORK_NOJOB;
 998                         if (pipe(pip) < 0)
 999                                 error("Pipe call failed: %s", strerror(errno));
1000                 }
1001                 if (cmdentry.cmdtype == CMDNORMAL &&
1002                     cmd->ncmd.redirect == NULL &&
1003                     varlist.list == NULL &&
1004                     (mode == FORK_FG || mode == FORK_NOJOB) &&
1005                     !disvforkset() && !iflag && !mflag) {
1006                         vforkexecshell(jp, argv, environment(), path,
1007                             cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL);
1008                         goto parent;
1009                 }
1010                 if (forkshell(jp, cmd, mode) != 0)
1011                         goto parent;    /* at end of routine */
1012                 if (flags & EV_BACKCMD) {
1013                         FORCEINTON;
1014                         close(pip[0]);
1015                         if (pip[1] != 1) {
1016                                 dup2(pip[1], 1);
1017                                 close(pip[1]);
1018                         }
1019                         flags &= ~EV_BACKCMD;
1020                 }
1021                 flags |= EV_EXIT;
1022         }
1023
1024         /* This is the child process if a fork occurred. */
1025         /* Execute the command. */
1026         if (cmdentry.cmdtype == CMDFUNCTION) {
1027 #ifdef DEBUG
1028                 trputs("Shell function:  ");  trargs(argv);
1029 #endif
1030                 saveparam = shellparam;
1031                 shellparam.malloc = 0;
1032                 shellparam.reset = 1;
1033                 shellparam.nparam = argc - 1;
1034                 shellparam.p = argv + 1;
1035                 shellparam.optnext = NULL;
1036                 INTOFF;
1037                 savelocalvars = localvars;
1038                 localvars = NULL;
1039                 reffunc(cmdentry.u.func);
1040                 savehandler = handler;
1041                 if (setjmp(jmploc.loc)) {
1042                         freeparam(&shellparam);
1043                         shellparam = saveparam;
1044                         popredir();
1045                         unreffunc(cmdentry.u.func);
1046                         poplocalvars();
1047                         localvars = savelocalvars;
1048                         funcnest--;
1049                         handler = savehandler;
1050                         longjmp(handler->loc, 1);
1051                 }
1052                 handler = &jmploc;
1053                 funcnest++;
1054                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
1055                 INTON;
1056                 for (sp = varlist.list ; sp ; sp = sp->next)
1057                         mklocal(sp->text);
1058                 exitstatus = oexitstatus;
1059                 evaltree(getfuncnode(cmdentry.u.func),
1060                     flags & (EV_TESTED | EV_EXIT));
1061                 INTOFF;
1062                 unreffunc(cmdentry.u.func);
1063                 poplocalvars();
1064                 localvars = savelocalvars;
1065                 freeparam(&shellparam);
1066                 shellparam = saveparam;
1067                 handler = savehandler;
1068                 funcnest--;
1069                 popredir();
1070                 INTON;
1071                 if (evalskip == SKIPRETURN) {
1072                         evalskip = 0;
1073                         skipcount = 0;
1074                 }
1075                 if (jp)
1076                         exitshell(exitstatus);
1077         } else if (cmdentry.cmdtype == CMDBUILTIN) {
1078 #ifdef DEBUG
1079                 trputs("builtin command:  ");  trargs(argv);
1080 #endif
1081                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
1082                 if (flags == EV_BACKCMD) {
1083                         memout.nleft = 0;
1084                         memout.nextc = memout.buf;
1085                         memout.bufsize = 64;
1086                         mode |= REDIR_BACKQ;
1087                 }
1088                 savecmdname = commandname;
1089                 savetopfile = getcurrentfile();
1090                 cmdenviron = varlist.list;
1091                 e = -1;
1092                 savehandler = handler;
1093                 if (setjmp(jmploc.loc)) {
1094                         e = exception;
1095                         if (e == EXINT)
1096                                 exitstatus = SIGINT+128;
1097                         else if (e != EXEXIT)
1098                                 exitstatus = 2;
1099                         goto cmddone;
1100                 }
1101                 handler = &jmploc;
1102                 redirect(cmd->ncmd.redirect, mode);
1103                 outclearerror(out1);
1104                 /*
1105                  * If there is no command word, redirection errors should
1106                  * not be fatal but assignment errors should.
1107                  */
1108                 if (argc == 0)
1109                         cmdentry.special = 1;
1110                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1111                 if (argc > 0)
1112                         bltinsetlocale();
1113                 commandname = argv[0];
1114                 argptr = argv + 1;
1115                 nextopt_optptr = NULL;          /* initialize nextopt */
1116                 builtin_flags = flags;
1117                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1118                 flushall();
1119                 if (outiserror(out1)) {
1120                         warning("write error on stdout");
1121                         if (exitstatus == 0 || exitstatus == 1)
1122                                 exitstatus = 2;
1123                 }
1124 cmddone:
1125                 if (argc > 0)
1126                         bltinunsetlocale();
1127                 cmdenviron = NULL;
1128                 out1 = &output;
1129                 out2 = &errout;
1130                 freestdout();
1131                 handler = savehandler;
1132                 commandname = savecmdname;
1133                 if (jp)
1134                         exitshell(exitstatus);
1135                 if (flags == EV_BACKCMD) {
1136                         backcmd->buf = memout.buf;
1137                         backcmd->nleft = memout.nextc - memout.buf;
1138                         memout.buf = NULL;
1139                 }
1140                 if (cmdentry.u.index != EXECCMD)
1141                         popredir();
1142                 if (e != -1) {
1143                         if ((e != EXERROR && e != EXEXEC)
1144                             || cmdentry.special)
1145                                 exraise(e);
1146                         popfilesupto(savetopfile);
1147                         if (flags != EV_BACKCMD)
1148                                 FORCEINTON;
1149                 }
1150         } else {
1151 #ifdef DEBUG
1152                 trputs("normal command:  ");  trargs(argv);
1153 #endif
1154                 redirect(cmd->ncmd.redirect, 0);
1155                 for (sp = varlist.list ; sp ; sp = sp->next)
1156                         setvareq(sp->text, VEXPORT|VSTACK);
1157                 envp = environment();
1158                 shellexec(argv, envp, path, cmdentry.u.index);
1159                 /*NOTREACHED*/
1160         }
1161         goto out;
1162
1163 parent: /* parent process gets here (if we forked) */
1164         if (mode == FORK_FG) {  /* argument to fork */
1165                 INTOFF;
1166                 exitstatus = waitforjob(jp, &realstatus);
1167                 INTON;
1168                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1169                         evalskip = SKIPBREAK;
1170                         skipcount = loopnest;
1171                 }
1172         } else if (mode == FORK_NOJOB) {
1173                 backcmd->fd = pip[0];
1174                 close(pip[1]);
1175                 backcmd->jp = jp;
1176         }
1177
1178 out:
1179         if (lastarg)
1180                 setvar("_", lastarg, 0);
1181         if (do_clearcmdentry)
1182                 clearcmdentry();
1183 }
1184
1185
1186
1187 /*
1188  * Search for a command.  This is called before we fork so that the
1189  * location of the command will be available in the parent as well as
1190  * the child.  The check for "goodname" is an overly conservative
1191  * check that the name will not be subject to expansion.
1192  */
1193
1194 static void
1195 prehash(union node *n)
1196 {
1197         struct cmdentry entry;
1198
1199         if (n && n->type == NCMD && n->ncmd.args)
1200                 if (goodname(n->ncmd.args->narg.text))
1201                         find_command(n->ncmd.args->narg.text, &entry, 0,
1202                                      pathval());
1203 }
1204
1205
1206
1207 /*
1208  * Builtin commands.  Builtin commands whose functions are closely
1209  * tied to evaluation are implemented here.
1210  */
1211
1212 /*
1213  * No command given, a bltin command with no arguments, or a bltin command
1214  * with an invalid name.
1215  */
1216
1217 int
1218 bltincmd(int argc, char **argv)
1219 {
1220         if (argc > 1) {
1221                 out2fmt_flush("%s: not found\n", argv[1]);
1222                 return 127;
1223         }
1224         /*
1225          * Preserve exitstatus of a previous possible redirection
1226          * as POSIX mandates
1227          */
1228         return exitstatus;
1229 }
1230
1231
1232 /*
1233  * Handle break and continue commands.  Break, continue, and return are
1234  * all handled by setting the evalskip flag.  The evaluation routines
1235  * above all check this flag, and if it is set they start skipping
1236  * commands rather than executing them.  The variable skipcount is
1237  * the number of loops to break/continue, or the number of function
1238  * levels to return.  (The latter is always 1.)  It should probably
1239  * be an error to break out of more loops than exist, but it isn't
1240  * in the standard shell so we don't make it one here.
1241  */
1242
1243 int
1244 breakcmd(int argc, char **argv)
1245 {
1246         int n = argc > 1 ? number(argv[1]) : 1;
1247
1248         if (n > loopnest)
1249                 n = loopnest;
1250         if (n > 0) {
1251                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1252                 skipcount = n;
1253         }
1254         return 0;
1255 }
1256
1257 /*
1258  * The `command' command.
1259  */
1260 int
1261 commandcmd(int argc __unused, char **argv __unused)
1262 {
1263         const char *path;
1264         int ch;
1265         int cmd = -1;
1266
1267         path = bltinlookup("PATH", 1);
1268
1269         while ((ch = nextopt("pvV")) != '\0') {
1270                 switch (ch) {
1271                 case 'p':
1272                         path = _PATH_STDPATH;
1273                         break;
1274                 case 'v':
1275                         cmd = TYPECMD_SMALLV;
1276                         break;
1277                 case 'V':
1278                         cmd = TYPECMD_BIGV;
1279                         break;
1280                 }
1281         }
1282
1283         if (cmd != -1) {
1284                 if (*argptr == NULL || argptr[1] != NULL)
1285                         error("wrong number of arguments");
1286                 return typecmd_impl(2, argptr - 1, cmd, path);
1287         }
1288         if (*argptr != NULL)
1289                 error("commandcmd bad call");
1290
1291         /*
1292          * Do nothing successfully if no command was specified;
1293          * ksh also does this.
1294          */
1295         return 0;
1296 }
1297
1298
1299 /*
1300  * The return command.
1301  */
1302
1303 int
1304 returncmd(int argc, char **argv)
1305 {
1306         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1307
1308         evalskip = SKIPRETURN;
1309         skipcount = 1;
1310         return ret;
1311 }
1312
1313
1314 int
1315 falsecmd(int argc __unused, char **argv __unused)
1316 {
1317         return 1;
1318 }
1319
1320
1321 int
1322 truecmd(int argc __unused, char **argv __unused)
1323 {
1324         return 0;
1325 }
1326
1327
1328 int
1329 execcmd(int argc, char **argv)
1330 {
1331         /*
1332          * Because we have historically not supported any options,
1333          * only treat "--" specially.
1334          */
1335         if (argc > 1 && strcmp(argv[1], "--") == 0)
1336                 argc--, argv++;
1337         if (argc > 1) {
1338                 struct strlist *sp;
1339
1340                 iflag = 0;              /* exit on error */
1341                 mflag = 0;
1342                 optschanged();
1343                 for (sp = cmdenviron; sp ; sp = sp->next)
1344                         setvareq(sp->text, VEXPORT|VSTACK);
1345                 shellexec(argv + 1, environment(), pathval(), 0);
1346
1347         }
1348         return 0;
1349 }
1350
1351
1352 int
1353 timescmd(int argc __unused, char **argv __unused)
1354 {
1355         struct rusage ru;
1356         long shumins, shsmins, chumins, chsmins;
1357         double shusecs, shssecs, chusecs, chssecs;
1358
1359         if (getrusage(RUSAGE_SELF, &ru) < 0)
1360                 return 1;
1361         shumins = ru.ru_utime.tv_sec / 60;
1362         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1363         shsmins = ru.ru_stime.tv_sec / 60;
1364         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1365         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1366                 return 1;
1367         chumins = ru.ru_utime.tv_sec / 60;
1368         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1369         chsmins = ru.ru_stime.tv_sec / 60;
1370         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1371         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1372             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1373         return 0;
1374 }