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  * @(#)eval.c   8.9 (Berkeley) 6/8/95
  33  * $FreeBSD: head/bin/sh/eval.c 247206 2013-02-23 22:50:57Z jilles $
  34  */
  35
  36 #include <sys/time.h>
  37 #include <sys/resource.h>
  38 #include <sys/wait.h> /* For WIFSIGNALED(status) */
  39
  40 #include <errno.h>
  41 #include <paths.h>
  42 #include <signal.h>
  43 #include <stdlib.h>
  44 #include <unistd.h>
  45
  46 /*
  47  * Evaluate a command.
  48  */
  49
  50 #include "shell.h"
  51 #include "nodes.h"
  52 #include "syntax.h"
  53 #include "expand.h"
  54 #include "parser.h"
  55 #include "jobs.h"
  56 #include "eval.h"
  57 #include "builtins.h"
  58 #include "options.h"
  59 #include "exec.h"
  60 #include "redir.h"
  61 #include "input.h"
  62 #include "output.h"
  63 #include "trap.h"
  64 #include "var.h"
  65 #include "memalloc.h"
  66 #include "error.h"
  67 #include "show.h"
  68 #include "mystring.h"
  69 #ifndef NO_HISTORY
  70 #include "myhistedit.h"
  71 #endif
  72
  73
  74 int evalskip;                   /* set if we are skipping commands */
  75 int skipcount;                  /* number of levels to skip */
  76 MKINIT int loopnest;            /* current loop nesting level */
  77 int funcnest;                   /* depth of function calls */
  78 static int builtin_flags;       /* evalcommand flags for builtins */
  79
  80
  81 const char *commandname;
  82 struct strlist *cmdenviron;
  83 int exitstatus;                 /* exit status of last command */
  84 int oexitstatus;                /* saved exit status */
  85
  86
  87 static void evalloop(union node *, int);
  88 static void evalfor(union node *, int);
  89 static union node *evalcase(union node *);
  90 static void evalsubshell(union node *, int);
  91 static void evalredir(union node *, int);
  92 static void exphere(union node *, struct arglist *);
  93 static void expredir(union node *);
  94 static void evalpipe(union node *);
  95 static int is_valid_fast_cmdsubst(union node *n);
  96 static void evalcommand(union node *, int, struct backcmd *);
  97 static void prehash(union node *);
  98
  99
 100 /*
 101  * Called to reset things after an exception.
 102  */
 103
 104 #ifdef mkinit
 105 INCLUDE "eval.h"
 106
 107 RESET {
 108         evalskip = 0;
 109         loopnest = 0;
 110         funcnest = 0;
 111 }
 112 #endif
 113
 114
 115
 116 /*
 117  * The eval command.
 118  */
 119
 120 int
 121 evalcmd(int argc, char **argv)
 122 {
 123         char *p;
 124         char *concat;
 125         char **ap;
 126
 127         if (argc > 1) {
 128                 p = argv[1];
 129                 if (argc > 2) {
 130                         STARTSTACKSTR(concat);
 131                         ap = argv + 2;
 132                         for (;;) {
 133                                 STPUTS(p, concat);
 134                                 if ((p = *ap++) == NULL)
 135                                         break;
 136                                 STPUTC(' ', concat);
 137                         }
 138                         STPUTC('\0', concat);
 139                         p = grabstackstr(concat);
 140                 }
 141                 evalstring(p, builtin_flags);
 142         } else
 143                 exitstatus = 0;
 144         return exitstatus;
 145 }
 146
 147
 148 /*
 149  * Execute a command or commands contained in a string.
 150  */
 151
 152 void
 153 evalstring(char *s, int flags)
 154 {
 155         union node *n;
 156         struct stackmark smark;
 157         int flags_exit;
 158         int any;
 159
 160         flags_exit = flags & EV_EXIT;
 161         flags &= ~EV_EXIT;
 162         any = 0;
 163         setstackmark(&smark);
 164         setinputstring(s, 1);
 165         while ((n = parsecmd(0)) != NEOF) {
 166                 if (n != NULL && !nflag) {
 167                         if (flags_exit && preadateof())
 168                                 evaltree(n, flags | EV_EXIT);
 169                         else
 170                                 evaltree(n, flags);
 171                         any = 1;
 172                 }
 173                 popstackmark(&smark);
 174                 setstackmark(&smark);
 175         }
 176         popfile();
 177         popstackmark(&smark);
 178         if (!any)
 179                 exitstatus = 0;
 180         if (flags_exit)
 181                 exraise(EXEXIT);
 182 }
 183
 184
 185 /*
 186  * Evaluate a parse tree.  The value is left in the global variable
 187  * exitstatus.
 188  */
 189
 190 void
 191 evaltree(union node *n, int flags)
 192 {
 193         int do_etest;
 194         union node *next;
 195         struct stackmark smark;
 196
 197         setstackmark(&smark);
 198         do_etest = 0;
 199         if (n == NULL) {
 200                 TRACE(("evaltree(NULL) called\n"));
 201                 exitstatus = 0;
 202                 goto out;
 203         }
 204         do {
 205                 next = NULL;
 206 #ifndef NO_HISTORY
 207                 displayhist = 1;        /* show history substitutions done with fc */
 208 #endif
 209                 TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
 210                 switch (n->type) {
 211                 case NSEMI:
 212                         evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
 213                         if (evalskip)
 214                                 goto out;
 215                         next = n->nbinary.ch2;
 216                         break;
 217                 case NAND:
 218                         evaltree(n->nbinary.ch1, EV_TESTED);
 219                         if (evalskip || exitstatus != 0) {
 220                                 goto out;
 221                         }
 222                         next = n->nbinary.ch2;
 223                         break;
 224                 case NOR:
 225                         evaltree(n->nbinary.ch1, EV_TESTED);
 226                         if (evalskip || exitstatus == 0)
 227                                 goto out;
 228                         next = n->nbinary.ch2;
 229                         break;
 230                 case NREDIR:
 231                         evalredir(n, flags);
 232                         break;
 233                 case NSUBSHELL:
 234                         evalsubshell(n, flags);
 235                         do_etest = !(flags & EV_TESTED);
 236                         break;
 237                 case NBACKGND:
 238                         evalsubshell(n, flags);
 239                         break;
 240                 case NIF: {
 241                         evaltree(n->nif.test, EV_TESTED);
 242                         if (evalskip)
 243                                 goto out;
 244                         if (exitstatus == 0)
 245                                 next = n->nif.ifpart;
 246                         else if (n->nif.elsepart)
 247                                 next = n->nif.elsepart;
 248                         else
 249                                 exitstatus = 0;
 250                         break;
 251                 }
 252                 case NWHILE:
 253                 case NUNTIL:
 254                         evalloop(n, flags & ~EV_EXIT);
 255                         break;
 256                 case NFOR:
 257                         evalfor(n, flags & ~EV_EXIT);
 258                         break;
 259                 case NCASE:
 260                         next = evalcase(n);
 261                         break;
 262                 case NCLIST:
 263                         next = n->nclist.body;
 264                         break;
 265                 case NCLISTFALLTHRU:
 266                         if (n->nclist.body) {
 267                                 evaltree(n->nclist.body, flags & ~EV_EXIT);
 268                                 if (evalskip)
 269                                         goto out;
 270                         }
 271                         next = n->nclist.next;
 272                         break;
 273                 case NDEFUN:
 274                         defun(n->narg.text, n->narg.next);
 275                         exitstatus = 0;
 276                         break;
 277                 case NNOT:
 278                         evaltree(n->nnot.com, EV_TESTED);
 279                         exitstatus = !exitstatus;
 280                         break;
 281
 282                 case NPIPE:
 283                         evalpipe(n);
 284                         do_etest = !(flags & EV_TESTED);
 285                         break;
 286                 case NCMD:
 287                         evalcommand(n, flags, NULL);
 288                         do_etest = !(flags & EV_TESTED);
 289                         break;
 290                 default:
 291                         out1fmt("Node type = %d\n", n->type);
 292                         flushout(&output);
 293                         break;
 294                 }
 295                 n = next;
 296                 popstackmark(&smark);
 297                 setstackmark(&smark);
 298         } while (n != NULL);
 299 out:
 300         popstackmark(&smark);
 301         if (pendingsig)
 302                 dotrap();
 303         if (eflag && exitstatus != 0 && do_etest)
 304                 exitshell(exitstatus);
 305         if (flags & EV_EXIT)
 306                 exraise(EXEXIT);
 307 }
 308
 309
 310 static void
 311 evalloop(union node *n, int flags)
 312 {
 313         int status;
 314
 315         loopnest++;
 316         status = 0;
 317         for (;;) {
 318                 evaltree(n->nbinary.ch1, EV_TESTED);
 319                 if (evalskip) {
 320 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
 321                                 evalskip = 0;
 322                                 continue;
 323                         }
 324                         if (evalskip == SKIPBREAK && --skipcount <= 0)
 325                                 evalskip = 0;
 326                         if (evalskip == SKIPFUNC || evalskip == SKIPFILE)
 327                                 status = exitstatus;
 328                         break;
 329                 }
 330                 if (n->type == NWHILE) {
 331                         if (exitstatus != 0)
 332                                 break;
 333                 } else {
 334                         if (exitstatus == 0)
 335                                 break;
 336                 }
 337                 evaltree(n->nbinary.ch2, flags);
 338                 status = exitstatus;
 339                 if (evalskip)
 340                         goto skipping;
 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, 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 | EXP_REDIR);
 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 | EXP_REDIR);
 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, 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         setstackmark(&smark);
 651         result->fd = -1;
 652         result->buf = NULL;
 653         result->nleft = 0;
 654         result->jp = NULL;
 655         if (n == NULL) {
 656                 exitstatus = 0;
 657                 goto out;
 658         }
 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 out:
 701         popstackmark(&smark);
 702         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
 703                 result->fd, result->buf, result->nleft, result->jp));
 704 }
 705
 706 static int
 707 mustexpandto(const char *argtext, const char *mask)
 708 {
 709         for (;;) {
 710                 if (*argtext == CTLQUOTEMARK || *argtext == CTLQUOTEEND) {
 711                         argtext++;
 712                         continue;
 713                 }
 714                 if (*argtext == CTLESC)
 715                         argtext++;
 716                 else if (BASESYNTAX[(int)*argtext] == CCTL)
 717                         return (0);
 718                 if (*argtext != *mask)
 719                         return (0);
 720                 if (*argtext == '\0')
 721                         return (1);
 722                 argtext++;
 723                 mask++;
 724         }
 725 }
 726
 727 static int
 728 isdeclarationcmd(struct narg *arg)
 729 {
 730         int have_command = 0;
 731
 732         if (arg == NULL)
 733                 return (0);
 734         while (mustexpandto(arg->text, "command")) {
 735                 have_command = 1;
 736                 arg = &arg->next->narg;
 737                 if (arg == NULL)
 738                         return (0);
 739                 /*
 740                  * To also allow "command -p" and "command --" as part of
 741                  * a declaration command, add code here.
 742                  * We do not do this, as ksh does not do it either and it
 743                  * is not required by POSIX.
 744                  */
 745         }
 746         return (mustexpandto(arg->text, "export") ||
 747             mustexpandto(arg->text, "readonly") ||
 748             (mustexpandto(arg->text, "local") &&
 749                 (have_command || !isfunc("local"))));
 750 }
 751
 752 /*
 753  * Check if a builtin can safely be executed in the same process,
 754  * even though it should be in a subshell (command substitution).
 755  * Note that jobid, jobs, times and trap can show information not
 756  * available in a child process; this is deliberate.
 757  * The arguments should already have been expanded.
 758  */
 759 static int
 760 safe_builtin(int idx, int argc, char **argv)
 761 {
 762         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
 763             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
 764             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
 765             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
 766             idx == TYPECMD)
 767                 return (1);
 768         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
 769             idx == UMASKCMD)
 770                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
 771         if (idx == SETCMD)
 772                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
 773                     argv[1][0] == '+') && argv[1][1] == 'o' &&
 774                     argv[1][2] == '\0'));
 775         return (0);
 776 }
 777
 778 /*
 779  * Execute a simple command.
 780  * Note: This may or may not return if (flags & EV_EXIT).
 781  */
 782
 783 static void
 784 evalcommand(union node *cmd, int flgs, struct backcmd *backcmd)
 785 {
 786         union node *argp;
 787         struct arglist arglist;
 788         struct arglist varlist;
 789         volatile int flags = flgs;
 790         char **volatile argv;
 791         volatile 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 *volatile jp;
 799         struct jmploc jmploc;
 800         struct jmploc *savehandler;
 801         const char *savecmdname;
 802         struct shparam saveparam;
 803         struct localvar *savelocalvars;
 804         struct parsefile *savetopfile;
 805         volatile int e;
 806         char *volatile lastarg;
 807         int realstatus;
 808         volatile 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 == SKIPFUNC) {
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         if (funcnest) {
1309                 evalskip = SKIPFUNC;
1310                 skipcount = 1;
1311         } else {
1312                 /* skip the rest of the file */
1313                 evalskip = SKIPFILE;
1314                 skipcount = 1;
1315         }
1316         return ret;
1317 }
1318
1319
1320 int
1321 falsecmd(int argc __unused, char **argv __unused)
1322 {
1323         return 1;
1324 }
1325
1326
1327 int
1328 truecmd(int argc __unused, char **argv __unused)
1329 {
1330         return 0;
1331 }
1332
1333
1334 int
1335 execcmd(int argc, char **argv)
1336 {
1337         /*
1338          * Because we have historically not supported any options,
1339          * only treat "--" specially.
1340          */
1341         if (argc > 1 && strcmp(argv[1], "--") == 0)
1342                 argc--, argv++;
1343         if (argc > 1) {
1344                 struct strlist *sp;
1345
1346                 iflag = 0;              /* exit on error */
1347                 mflag = 0;
1348                 optschanged();
1349                 for (sp = cmdenviron; sp ; sp = sp->next)
1350                         setvareq(sp->text, VEXPORT|VSTACK);
1351                 shellexec(argv + 1, environment(), pathval(), 0);
1352
1353         }
1354         return 0;
1355 }
1356
1357
1358 int
1359 timescmd(int argc __unused, char **argv __unused)
1360 {
1361         struct rusage ru;
1362         long shumins, shsmins, chumins, chsmins;
1363         double shusecs, shssecs, chusecs, chssecs;
1364
1365         if (getrusage(RUSAGE_SELF, &ru) < 0)
1366                 return 1;
1367         shumins = ru.ru_utime.tv_sec / 60;
1368         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1369         shsmins = ru.ru_stime.tv_sec / 60;
1370         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1371         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1372                 return 1;
1373         chumins = ru.ru_utime.tv_sec / 60;
1374         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1375         chsmins = ru.ru_stime.tv_sec / 60;
1376         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1377         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1378             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1379         return 0;
1380 }