sh: Allow EV_EXIT through function calls.
[dragonfly.git] / bin / sh / eval.c
1 /*-
2  * Copyright (c) 1993
3  *      The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Kenneth Almquist.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. All advertising materials mentioning features or use of this software
17  *    must display the following acknowledgement:
18  *      This product includes software developed by the University of
19  *      California, Berkeley and its contributors.
20  * 4. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  *
36  * @(#)eval.c   8.9 (Berkeley) 6/8/95
37  * $FreeBSD: src/bin/sh/eval.c,v 1.102 2011/04/23 22:28:56 jilles Exp $
38  */
39
40 #include <sys/time.h>
41 #include <sys/resource.h>
42 #include <sys/wait.h> /* For WIFSIGNALED(status) */
43
44 #include <errno.h>
45 #include <paths.h>
46 #include <signal.h>
47 #include <stdlib.h>
48 #include <unistd.h>
49
50 /*
51  * Evaluate a command.
52  */
53
54 #include "shell.h"
55 #include "nodes.h"
56 #include "syntax.h"
57 #include "expand.h"
58 #include "parser.h"
59 #include "jobs.h"
60 #include "eval.h"
61 #include "builtins.h"
62 #include "options.h"
63 #include "exec.h"
64 #include "redir.h"
65 #include "input.h"
66 #include "output.h"
67 #include "trap.h"
68 #include "var.h"
69 #include "memalloc.h"
70 #include "error.h"
71 #include "show.h"
72 #include "mystring.h"
73 #ifndef NO_HISTORY
74 #include "myhistedit.h"
75 #endif
76
77
78 int evalskip;                   /* set if we are skipping commands */
79 static int skipcount;           /* number of levels to skip */
80 MKINIT int loopnest;            /* current loop nesting level */
81 int funcnest;                   /* depth of function calls */
82 static int builtin_flags;       /* evalcommand flags for builtins */
83
84
85 const char *commandname;
86 struct strlist *cmdenviron;
87 int exitstatus;                 /* exit status of last command */
88 int oexitstatus;                /* saved exit status */
89
90
91 static void evalloop(union node *, int);
92 static void evalfor(union node *, int);
93 static void evalcase(union node *, int);
94 static void evalsubshell(union node *, int);
95 static void evalredir(union node *, int);
96 static void expredir(union node *);
97 static void evalpipe(union node *);
98 static int is_valid_fast_cmdsubst(union node *n);
99 static void evalcommand(union node *, int, struct backcmd *);
100 static void prehash(union node *);
101
102
103 /*
104  * Called to reset things after an exception.
105  */
106
107 #ifdef mkinit
108 INCLUDE "eval.h"
109
110 RESET {
111         evalskip = 0;
112         loopnest = 0;
113         funcnest = 0;
114 }
115 #endif
116
117
118
119 /*
120  * The eval command.
121  */
122
123 int
124 evalcmd(int argc, char **argv)
125 {
126         char *p;
127         char *concat;
128         char **ap;
129
130         if (argc > 1) {
131                 p = argv[1];
132                 if (argc > 2) {
133                         STARTSTACKSTR(concat);
134                         ap = argv + 2;
135                         for (;;) {
136                                 STPUTS(p, concat);
137                                 if ((p = *ap++) == NULL)
138                                         break;
139                                 STPUTC(' ', concat);
140                         }
141                         STPUTC('\0', concat);
142                         p = grabstackstr(concat);
143                 }
144                 evalstring(p, builtin_flags & EV_TESTED);
145         } else
146                 exitstatus = 0;
147         return exitstatus;
148 }
149
150
151 /*
152  * Execute a command or commands contained in a string.
153  */
154
155 void
156 evalstring(char *s, int flags)
157 {
158         union node *n;
159         struct stackmark smark;
160         int flags_exit;
161         int any;
162
163         flags_exit = flags & EV_EXIT;
164         flags &= ~EV_EXIT;
165         any = 0;
166         setstackmark(&smark);
167         setinputstring(s, 1);
168         while ((n = parsecmd(0)) != NEOF) {
169                 if (n != NULL) {
170                         if (flags_exit && preadateof())
171                                 evaltree(n, flags | EV_EXIT);
172                         else
173                                 evaltree(n, flags);
174                         any = 1;
175                 }
176                 popstackmark(&smark);
177         }
178         popfile();
179         popstackmark(&smark);
180         if (!any)
181                 exitstatus = 0;
182         if (flags_exit)
183                 exraise(EXEXIT);
184 }
185
186
187 /*
188  * Evaluate a parse tree.  The value is left in the global variable
189  * exitstatus.
190  */
191
192 void
193 evaltree(union node *n, int flags)
194 {
195         int do_etest;
196         union node *next;
197
198         do_etest = 0;
199         if (n == NULL) {
200                 TRACE(("evaltree(NULL) called\n"));
201                 exitstatus = 0;
202                 goto out;
203         }
204         do {
205                 next = NULL;
206 #ifndef NO_HISTORY
207                 displayhist = 1;        /* show history substitutions done with fc */
208 #endif
209                 TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
210                 switch (n->type) {
211                 case NSEMI:
212                         evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
213                         if (evalskip)
214                                 goto out;
215                         next = n->nbinary.ch2;
216                         break;
217                 case NAND:
218                         evaltree(n->nbinary.ch1, EV_TESTED);
219                         if (evalskip || exitstatus != 0) {
220                                 goto out;
221                         }
222                         next = n->nbinary.ch2;
223                         break;
224                 case NOR:
225                         evaltree(n->nbinary.ch1, EV_TESTED);
226                         if (evalskip || exitstatus == 0)
227                                 goto out;
228                         next = n->nbinary.ch2;
229                         break;
230                 case NREDIR:
231                         evalredir(n, flags);
232                         break;
233                 case NSUBSHELL:
234                         evalsubshell(n, flags);
235                         do_etest = !(flags & EV_TESTED);
236                         break;
237                 case NBACKGND:
238                         evalsubshell(n, flags);
239                         break;
240                 case NIF: {
241                         evaltree(n->nif.test, EV_TESTED);
242                         if (evalskip)
243                                 goto out;
244                         if (exitstatus == 0)
245                                 next = n->nif.ifpart;
246                         else if (n->nif.elsepart)
247                                 next = n->nif.elsepart;
248                         else
249                                 exitstatus = 0;
250                         break;
251                 }
252                 case NWHILE:
253                 case NUNTIL:
254                         evalloop(n, flags & ~EV_EXIT);
255                         break;
256                 case NFOR:
257                         evalfor(n, flags & ~EV_EXIT);
258                         break;
259                 case NCASE:
260                         evalcase(n, flags);
261                         break;
262                 case NDEFUN:
263                         defun(n->narg.text, n->narg.next);
264                         exitstatus = 0;
265                         break;
266                 case NNOT:
267                         evaltree(n->nnot.com, EV_TESTED);
268                         exitstatus = !exitstatus;
269                         break;
270
271                 case NPIPE:
272                         evalpipe(n);
273                         do_etest = !(flags & EV_TESTED);
274                         break;
275                 case NCMD:
276                         evalcommand(n, flags, NULL);
277                         do_etest = !(flags & EV_TESTED);
278                         break;
279                 default:
280                         out1fmt("Node type = %d\n", n->type);
281                         flushout(&output);
282                         break;
283                 }
284                 n = next;
285         } while (n != NULL);
286 out:
287         if (pendingsigs)
288                 dotrap();
289         if (eflag && exitstatus != 0 && do_etest)
290                 exitshell(exitstatus);
291         if (flags & EV_EXIT)
292                 exraise(EXEXIT);
293 }
294
295
296 static void
297 evalloop(union node *n, int flags)
298 {
299         int status;
300
301         loopnest++;
302         status = 0;
303         for (;;) {
304                 evaltree(n->nbinary.ch1, EV_TESTED);
305                 if (evalskip) {
306 skipping:         if (evalskip == SKIPCONT && --skipcount <= 0) {
307                                 evalskip = 0;
308                                 continue;
309                         }
310                         if (evalskip == SKIPBREAK && --skipcount <= 0)
311                                 evalskip = 0;
312                         if (evalskip == SKIPFUNC || evalskip == SKIPFILE)
313                                 status = exitstatus;
314                         break;
315                 }
316                 if (n->type == NWHILE) {
317                         if (exitstatus != 0)
318                                 break;
319                 } else {
320                         if (exitstatus == 0)
321                                 break;
322                 }
323                 evaltree(n->nbinary.ch2, flags);
324                 status = exitstatus;
325                 if (evalskip)
326                         goto skipping;
327         }
328         loopnest--;
329         exitstatus = status;
330 }
331
332
333
334 static void
335 evalfor(union node *n, int flags)
336 {
337         struct arglist arglist;
338         union node *argp;
339         struct strlist *sp;
340         struct stackmark smark;
341
342         setstackmark(&smark);
343         arglist.lastp = &arglist.list;
344         for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
345                 oexitstatus = exitstatus;
346                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
347                 if (evalskip)
348                         goto out;
349         }
350         *arglist.lastp = NULL;
351
352         exitstatus = 0;
353         loopnest++;
354         for (sp = arglist.list ; sp ; sp = sp->next) {
355                 setvar(n->nfor.var, sp->text, 0);
356                 evaltree(n->nfor.body, flags);
357                 if (evalskip) {
358                         if (evalskip == SKIPCONT && --skipcount <= 0) {
359                                 evalskip = 0;
360                                 continue;
361                         }
362                         if (evalskip == SKIPBREAK && --skipcount <= 0)
363                                 evalskip = 0;
364                         break;
365                 }
366         }
367         loopnest--;
368 out:
369         popstackmark(&smark);
370 }
371
372
373
374 static void
375 evalcase(union node *n, int flags)
376 {
377         union node *cp;
378         union node *patp;
379         struct arglist arglist;
380         struct stackmark smark;
381
382         setstackmark(&smark);
383         arglist.lastp = &arglist.list;
384         oexitstatus = exitstatus;
385         exitstatus = 0;
386         expandarg(n->ncase.expr, &arglist, EXP_TILDE);
387         for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
388                 for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
389                         if (casematch(patp, arglist.list->text)) {
390                                 if (evalskip == 0) {
391                                         evaltree(cp->nclist.body, flags);
392                                 }
393                                 goto out;
394                         }
395                 }
396         }
397 out:
398         popstackmark(&smark);
399 }
400
401
402
403 /*
404  * Kick off a subshell to evaluate a tree.
405  */
406
407 static void
408 evalsubshell(union node *n, int flags)
409 {
410         struct job *jp;
411         int backgnd = (n->type == NBACKGND);
412
413         expredir(n->nredir.redirect);
414         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
415             forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
416                 if (backgnd)
417                         flags &=~ EV_TESTED;
418                 redirect(n->nredir.redirect, 0);
419                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
420         } else if (!backgnd) {
421                 INTOFF;
422                 exitstatus = waitforjob(jp, NULL);
423                 INTON;
424         }
425 }
426
427
428 /*
429  * Evaluate a redirected compound command.
430  */
431
432 static void
433 evalredir(union node *n, int flags)
434 {
435         struct jmploc jmploc;
436         struct jmploc *savehandler;
437         volatile int in_redirect = 1;
438
439         expredir(n->nredir.redirect);
440         savehandler = handler;
441         if (setjmp(jmploc.loc)) {
442                 int e;
443
444                 handler = savehandler;
445                 e = exception;
446                 popredir();
447                 if (e == EXERROR || e == EXEXEC) {
448                         if (in_redirect) {
449                                 exitstatus = 2;
450                                 return;
451                         }
452                 }
453                 longjmp(handler->loc, 1);
454         } else {
455                 INTOFF;
456                 handler = &jmploc;
457                 redirect(n->nredir.redirect, REDIR_PUSH);
458                 in_redirect = 0;
459                 INTON;
460                 evaltree(n->nredir.n, flags);
461         }
462         INTOFF;
463         handler = savehandler;
464         popredir();
465         INTON;
466 }
467
468
469 /*
470  * Compute the names of the files in a redirection list.
471  */
472
473 static void
474 expredir(union node *n)
475 {
476         union node *redir;
477
478         for (redir = n ; redir ; redir = redir->nfile.next) {
479                 struct arglist fn;
480                 fn.lastp = &fn.list;
481                 oexitstatus = exitstatus;
482                 switch (redir->type) {
483                 case NFROM:
484                 case NTO:
485                 case NFROMTO:
486                 case NAPPEND:
487                 case NCLOBBER:
488                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
489                         redir->nfile.expfname = fn.list->text;
490                         break;
491                 case NFROMFD:
492                 case NTOFD:
493                         if (redir->ndup.vname) {
494                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
495                                 fixredir(redir, fn.list->text, 1);
496                         }
497                         break;
498                 }
499         }
500 }
501
502
503
504 /*
505  * Evaluate a pipeline.  All the processes in the pipeline are children
506  * of the process creating the pipeline.  (This differs from some versions
507  * of the shell, which make the last process in a pipeline the parent
508  * of all the rest.)
509  */
510
511 static void
512 evalpipe(union node *n)
513 {
514         struct job *jp;
515         struct nodelist *lp;
516         int pipelen;
517         int prevfd;
518         int pip[2];
519
520         TRACE(("evalpipe(%p) called\n", (void *)n));
521         pipelen = 0;
522         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
523                 pipelen++;
524         INTOFF;
525         jp = makejob(n, pipelen);
526         prevfd = -1;
527         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
528                 prehash(lp->n);
529                 pip[1] = -1;
530                 if (lp->next) {
531                         if (pipe(pip) < 0) {
532                                 if (prevfd >= 0)
533                                         close(prevfd);
534                                 error("Pipe call failed: %s", strerror(errno));
535                         }
536                 }
537                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
538                         INTON;
539                         if (prevfd > 0) {
540                                 dup2(prevfd, 0);
541                                 close(prevfd);
542                         }
543                         if (pip[1] >= 0) {
544                                 if (!(prevfd >= 0 && pip[0] == 0))
545                                         close(pip[0]);
546                                 if (pip[1] != 1) {
547                                         dup2(pip[1], 1);
548                                         close(pip[1]);
549                                 }
550                         }
551                         evaltree(lp->n, EV_EXIT);
552                 }
553                 if (prevfd >= 0)
554                         close(prevfd);
555                 prevfd = pip[0];
556                 close(pip[1]);
557         }
558         INTON;
559         if (n->npipe.backgnd == 0) {
560                 INTOFF;
561                 exitstatus = waitforjob(jp, NULL);
562                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
563                 INTON;
564         }
565 }
566
567
568
569 static int
570 is_valid_fast_cmdsubst(union node *n)
571 {
572         union node *argp;
573
574         if (n->type != NCMD)
575                 return 0;
576         for (argp = n->ncmd.args ; argp ; argp = argp->narg.next)
577                 if (expandhassideeffects(argp->narg.text))
578                         return 0;
579         return 1;
580 }
581
582 /*
583  * Execute a command inside back quotes.  If it's a builtin command, we
584  * want to save its output in a block obtained from malloc.  Otherwise
585  * we fork off a subprocess and get the output of the command via a pipe.
586  * Should be called with interrupts off.
587  */
588
589 void
590 evalbackcmd(union node *n, struct backcmd *result)
591 {
592         int pip[2];
593         struct job *jp;
594         struct stackmark smark;         /* unnecessary */
595         struct jmploc jmploc;
596         struct jmploc *savehandler;
597
598         setstackmark(&smark);
599         result->fd = -1;
600         result->buf = NULL;
601         result->nleft = 0;
602         result->jp = NULL;
603         if (n == NULL) {
604                 exitstatus = 0;
605                 goto out;
606         }
607         if (is_valid_fast_cmdsubst(n)) {
608                 exitstatus = oexitstatus;
609                 savehandler = handler;
610                 if (setjmp(jmploc.loc)) {
611                         if (exception == EXERROR || exception == EXEXEC)
612                                 exitstatus = 2;
613                         else if (exception != 0) {
614                                 handler = savehandler;
615                                 longjmp(handler->loc, 1);
616                         }
617                 } else {
618                         handler = &jmploc;
619                         evalcommand(n, EV_BACKCMD, result);
620                 }
621                 handler = savehandler;
622         } else {
623                 exitstatus = 0;
624                 if (pipe(pip) < 0)
625                         error("Pipe call failed: %s", strerror(errno));
626                 jp = makejob(n, 1);
627                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
628                         FORCEINTON;
629                         close(pip[0]);
630                         if (pip[1] != 1) {
631                                 dup2(pip[1], 1);
632                                 close(pip[1]);
633                         }
634                         evaltree(n, EV_EXIT);
635                 }
636                 close(pip[1]);
637                 result->fd = pip[0];
638                 result->jp = jp;
639         }
640 out:
641         popstackmark(&smark);
642         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
643                 result->fd, result->buf, result->nleft, result->jp));
644 }
645
646 /*
647  * Check if a builtin can safely be executed in the same process,
648  * even though it should be in a subshell (command substitution).
649  * Note that jobid, jobs, times and trap can show information not
650  * available in a child process; this is deliberate.
651  * The arguments should already have been expanded.
652  */
653 static int
654 safe_builtin(int idx, int argc, char **argv)
655 {
656         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
657             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
658             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
659             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
660             idx == TYPECMD)
661                 return (1);
662         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
663             idx == UMASKCMD)
664                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
665         if (idx == SETCMD)
666                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
667                     argv[1][0] == '+') && argv[1][1] == 'o' &&
668                     argv[1][2] == '\0'));
669         return (0);
670 }
671
672 /*
673  * Execute a simple command.
674  * Note: This may or may not return if (flags & EV_EXIT).
675  */
676
677 static void
678 evalcommand(union node *cmd, int flgs, struct backcmd *backcmd)
679 {
680         struct stackmark smark;
681         union node *argp;
682         struct arglist arglist;
683         struct arglist varlist;
684         volatile int flags = flgs;
685         char **volatile argv;
686         volatile int argc;
687         char **envp;
688         int varflag;
689         struct strlist *sp;
690         int mode;
691         int pip[2];
692         struct cmdentry cmdentry;
693         struct job *volatile jp;
694         struct jmploc jmploc;
695         struct jmploc *savehandler;
696         const char *savecmdname;
697         struct shparam saveparam;
698         struct localvar *savelocalvars;
699         struct parsefile *savetopfile;
700         volatile int e;
701         char *volatile lastarg;
702         int realstatus;
703         volatile int do_clearcmdentry;
704         const char *path = pathval();
705
706         /* First expand the arguments. */
707         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
708         setstackmark(&smark);
709         arglist.lastp = &arglist.list;
710         varlist.lastp = &varlist.list;
711         varflag = 1;
712         jp = NULL;
713         do_clearcmdentry = 0;
714         oexitstatus = exitstatus;
715         exitstatus = 0;
716         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
717                 char *p = argp->narg.text;
718                 if (varflag && is_name(*p)) {
719                         do {
720                                 p++;
721                         } while (is_in_name(*p));
722                         if (*p == '=') {
723                                 expandarg(argp, &varlist, EXP_VARTILDE);
724                                 continue;
725                         }
726                 }
727                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
728                 varflag = 0;
729         }
730         *arglist.lastp = NULL;
731         *varlist.lastp = NULL;
732         expredir(cmd->ncmd.redirect);
733         argc = 0;
734         for (sp = arglist.list ; sp ; sp = sp->next)
735                 argc++;
736         /* Add one slot at the beginning for tryexec(). */
737         argv = stalloc(sizeof (char *) * (argc + 2));
738         argv++;
739
740         for (sp = arglist.list ; sp ; sp = sp->next) {
741                 TRACE(("evalcommand arg: %s\n", sp->text));
742                 *argv++ = sp->text;
743         }
744         *argv = NULL;
745         lastarg = NULL;
746         if (iflag && funcnest == 0 && argc > 0)
747                 lastarg = argv[-1];
748         argv -= argc;
749
750         /* Print the command if xflag is set. */
751         if (xflag) {
752                 char sep = 0;
753                 const char *p;
754                 out2str(ps4val());
755                 for (sp = varlist.list ; sp ; sp = sp->next) {
756                         if (sep != 0)
757                                 out2c(' ');
758                         p = strchr(sp->text, '=');
759                         if (p != NULL) {
760                                 p++;
761                                 outbin(sp->text, p - sp->text, out2);
762                                 out2qstr(p);
763                         } else
764                                 out2qstr(sp->text);
765                         sep = ' ';
766                 }
767                 for (sp = arglist.list ; sp ; sp = sp->next) {
768                         if (sep != 0)
769                                 out2c(' ');
770                         /* Disambiguate command looking like assignment. */
771                         if (sp == arglist.list &&
772                                         strchr(sp->text, '=') != NULL &&
773                                         strchr(sp->text, '\'') == NULL) {
774                                 out2c('\'');
775                                 out2str(sp->text);
776                                 out2c('\'');
777                         } else
778                                 out2qstr(sp->text);
779                         sep = ' ';
780                 }
781                 out2c('\n');
782                 flushout(&errout);
783         }
784
785         /* Now locate the command. */
786         if (argc == 0) {
787                 /* Variable assignment(s) without command */
788                 cmdentry.cmdtype = CMDBUILTIN;
789                 cmdentry.u.index = BLTINCMD;
790                 cmdentry.special = 0;
791         } else {
792                 static const char PATH[] = "PATH=";
793                 int cmd_flags = 0, bltinonly = 0;
794
795                 /*
796                  * Modify the command lookup path, if a PATH= assignment
797                  * is present
798                  */
799                 for (sp = varlist.list ; sp ; sp = sp->next)
800                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
801                                 path = sp->text + sizeof(PATH) - 1;
802                                 /*
803                                  * On `PATH=... command`, we need to make
804                                  * sure that the command isn't using the
805                                  * non-updated hash table of the outer PATH
806                                  * setting and we need to make sure that
807                                  * the hash table isn't filled with items
808                                  * from the temporary setting.
809                                  *
810                                  * It would be better to forbit using and
811                                  * updating the table while this command
812                                  * runs, by the command finding mechanism
813                                  * is heavily integrated with hash handling,
814                                  * so we just delete the hash before and after
815                                  * the command runs. Partly deleting like
816                                  * changepatch() does doesn't seem worth the
817                                  * bookinging effort, since most such runs add
818                                  * directories in front of the new PATH.
819                                  */
820                                 clearcmdentry();
821                                 do_clearcmdentry = 1;
822                         }
823
824                 for (;;) {
825                         if (bltinonly) {
826                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
827                                 if (cmdentry.u.index < 0) {
828                                         cmdentry.u.index = BLTINCMD;
829                                         argv--;
830                                         argc++;
831                                         break;
832                                 }
833                         } else
834                                 find_command(argv[0], &cmdentry, cmd_flags, path);
835                         /* implement the bltin and command builtins here */
836                         if (cmdentry.cmdtype != CMDBUILTIN)
837                                 break;
838                         if (cmdentry.u.index == BLTINCMD) {
839                                 if (argc == 1)
840                                         break;
841                                 argv++;
842                                 argc--;
843                                 bltinonly = 1;
844                         } else if (cmdentry.u.index == COMMANDCMD) {
845                                 if (argc == 1)
846                                         break;
847                                 if (!strcmp(argv[1], "-p")) {
848                                         if (argc == 2)
849                                                 break;
850                                         if (argv[2][0] == '-') {
851                                                 if (strcmp(argv[2], "--"))
852                                                         break;
853                                                 if (argc == 3)
854                                                         break;
855                                                 argv += 3;
856                                                 argc -= 3;
857                                         } else {
858                                                 argv += 2;
859                                                 argc -= 2;
860                                         }
861                                         path = _PATH_STDPATH;
862                                         clearcmdentry();
863                                         do_clearcmdentry = 1;
864                                 } else if (!strcmp(argv[1], "--")) {
865                                         if (argc == 2)
866                                                 break;
867                                         argv += 2;
868                                         argc -= 2;
869                                 } else if (argv[1][0] == '-')
870                                         break;
871                                 else {
872                                         argv++;
873                                         argc--;
874                                 }
875                                 cmd_flags |= DO_NOFUNC;
876                                 bltinonly = 0;
877                         } else
878                                 break;
879                 }
880                 /*
881                  * Special builtins lose their special properties when
882                  * called via 'command'.
883                  */
884                 if (cmd_flags & DO_NOFUNC)
885                         cmdentry.special = 0;
886         }
887
888         /* Fork off a child process if necessary. */
889         if (cmd->ncmd.backgnd
890          || ((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
891             && ((flags & EV_EXIT) == 0 || have_traps()))
892          || ((flags & EV_BACKCMD) != 0
893             && (cmdentry.cmdtype != CMDBUILTIN ||
894                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
895                 jp = makejob(cmd, 1);
896                 mode = cmd->ncmd.backgnd;
897                 if (flags & EV_BACKCMD) {
898                         mode = FORK_NOJOB;
899                         if (pipe(pip) < 0)
900                                 error("Pipe call failed: %s", strerror(errno));
901                 }
902                 if (forkshell(jp, cmd, mode) != 0)
903                         goto parent;    /* at end of routine */
904                 if (flags & EV_BACKCMD) {
905                         FORCEINTON;
906                         close(pip[0]);
907                         if (pip[1] != 1) {
908                                 dup2(pip[1], 1);
909                                 close(pip[1]);
910                         }
911                 }
912                 flags |= EV_EXIT;
913         }
914
915         /* This is the child process if a fork occurred. */
916         /* Execute the command. */
917         if (cmdentry.cmdtype == CMDFUNCTION) {
918 #ifdef DEBUG
919                 trputs("Shell function:  ");  trargs(argv);
920 #endif
921                 saveparam = shellparam;
922                 shellparam.malloc = 0;
923                 shellparam.reset = 1;
924                 shellparam.nparam = argc - 1;
925                 shellparam.p = argv + 1;
926                 shellparam.optnext = NULL;
927                 INTOFF;
928                 savelocalvars = localvars;
929                 localvars = NULL;
930                 reffunc(cmdentry.u.func);
931                 savehandler = handler;
932                 if (setjmp(jmploc.loc)) {
933                         freeparam(&shellparam);
934                         shellparam = saveparam;
935                         popredir();
936                         unreffunc(cmdentry.u.func);
937                         poplocalvars();
938                         localvars = savelocalvars;
939                         funcnest--;
940                         handler = savehandler;
941                         longjmp(handler->loc, 1);
942                 }
943                 handler = &jmploc;
944                 funcnest++;
945                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
946                 INTON;
947                 for (sp = varlist.list ; sp ; sp = sp->next)
948                         mklocal(sp->text);
949                 exitstatus = oexitstatus;
950                 evaltree(getfuncnode(cmdentry.u.func),
951                     flags & (EV_TESTED | EV_EXIT));
952                 INTOFF;
953                 unreffunc(cmdentry.u.func);
954                 poplocalvars();
955                 localvars = savelocalvars;
956                 freeparam(&shellparam);
957                 shellparam = saveparam;
958                 handler = savehandler;
959                 funcnest--;
960                 popredir();
961                 INTON;
962                 if (evalskip == SKIPFUNC) {
963                         evalskip = 0;
964                         skipcount = 0;
965                 }
966                 if (jp)
967                         exitshell(exitstatus);
968         } else if (cmdentry.cmdtype == CMDBUILTIN) {
969 #ifdef DEBUG
970                 trputs("builtin command:  ");  trargs(argv);
971 #endif
972                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
973                 if (flags == EV_BACKCMD) {
974                         memout.nleft = 0;
975                         memout.nextc = memout.buf;
976                         memout.bufsize = 64;
977                         mode |= REDIR_BACKQ;
978                         cmdentry.special = 0;
979                 }
980                 savecmdname = commandname;
981                 savetopfile = getcurrentfile();
982                 cmdenviron = varlist.list;
983                 e = -1;
984                 savehandler = handler;
985                 if (setjmp(jmploc.loc)) {
986                         e = exception;
987                         if (e == EXINT)
988                                 exitstatus = SIGINT+128;
989                         else if (e != EXEXIT)
990                                 exitstatus = 2;
991                         goto cmddone;
992                 }
993                 handler = &jmploc;
994                 redirect(cmd->ncmd.redirect, mode);
995                 /*
996                  * If there is no command word, redirection errors should
997                  * not be fatal but assignment errors should.
998                  */
999                 if (argc == 0 && !(flags & EV_BACKCMD))
1000                         cmdentry.special = 1;
1001                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1002                 if (argc > 0)
1003                         bltinsetlocale();
1004                 commandname = argv[0];
1005                 argptr = argv + 1;
1006                 nextopt_optptr = NULL;          /* initialize nextopt */
1007                 builtin_flags = flags;
1008                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1009                 flushall();
1010 cmddone:
1011                 if (argc > 0)
1012                         bltinunsetlocale();
1013                 cmdenviron = NULL;
1014                 out1 = &output;
1015                 out2 = &errout;
1016                 freestdout();
1017                 handler = savehandler;
1018                 commandname = savecmdname;
1019                 if (jp)
1020                         exitshell(exitstatus);
1021                 if (flags == EV_BACKCMD) {
1022                         backcmd->buf = memout.buf;
1023                         backcmd->nleft = memout.nextc - memout.buf;
1024                         memout.buf = NULL;
1025                 }
1026                 if (cmdentry.u.index != EXECCMD)
1027                         popredir();
1028                 if (e != -1) {
1029                         if ((e != EXERROR && e != EXEXEC)
1030                             || cmdentry.special)
1031                                 exraise(e);
1032                         popfilesupto(savetopfile);
1033                         if (flags != EV_BACKCMD)
1034                                 FORCEINTON;
1035                 }
1036         } else {
1037 #ifdef DEBUG
1038                 trputs("normal command:  ");  trargs(argv);
1039 #endif
1040                 redirect(cmd->ncmd.redirect, 0);
1041                 for (sp = varlist.list ; sp ; sp = sp->next)
1042                         setvareq(sp->text, VEXPORT|VSTACK);
1043                 envp = environment();
1044                 shellexec(argv, envp, path, cmdentry.u.index);
1045                 /*NOTREACHED*/
1046         }
1047         goto out;
1048
1049 parent: /* parent process gets here (if we forked) */
1050         if (mode == FORK_FG) {  /* argument to fork */
1051                 INTOFF;
1052                 exitstatus = waitforjob(jp, &realstatus);
1053                 INTON;
1054                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1055                         evalskip = SKIPBREAK;
1056                         skipcount = loopnest;
1057                 }
1058         } else if (mode == FORK_NOJOB) {
1059                 backcmd->fd = pip[0];
1060                 close(pip[1]);
1061                 backcmd->jp = jp;
1062         }
1063
1064 out:
1065         if (lastarg)
1066                 setvar("_", lastarg, 0);
1067         if (do_clearcmdentry)
1068                 clearcmdentry();
1069         popstackmark(&smark);
1070 }
1071
1072
1073
1074 /*
1075  * Search for a command.  This is called before we fork so that the
1076  * location of the command will be available in the parent as well as
1077  * the child.  The check for "goodname" is an overly conservative
1078  * check that the name will not be subject to expansion.
1079  */
1080
1081 static void
1082 prehash(union node *n)
1083 {
1084         struct cmdentry entry;
1085
1086         if (n && n->type == NCMD && n->ncmd.args)
1087                 if (goodname(n->ncmd.args->narg.text))
1088                         find_command(n->ncmd.args->narg.text, &entry, 0,
1089                                      pathval());
1090 }
1091
1092
1093
1094 /*
1095  * Builtin commands.  Builtin commands whose functions are closely
1096  * tied to evaluation are implemented here.
1097  */
1098
1099 /*
1100  * No command given, a bltin command with no arguments, or a bltin command
1101  * with an invalid name.
1102  */
1103
1104 int
1105 bltincmd(int argc, char **argv)
1106 {
1107         if (argc > 1) {
1108                 out2fmt_flush("%s: not found\n", argv[1]);
1109                 return 127;
1110         }
1111         /*
1112          * Preserve exitstatus of a previous possible redirection
1113          * as POSIX mandates
1114          */
1115         return exitstatus;
1116 }
1117
1118
1119 /*
1120  * Handle break and continue commands.  Break, continue, and return are
1121  * all handled by setting the evalskip flag.  The evaluation routines
1122  * above all check this flag, and if it is set they start skipping
1123  * commands rather than executing them.  The variable skipcount is
1124  * the number of loops to break/continue, or the number of function
1125  * levels to return.  (The latter is always 1.)  It should probably
1126  * be an error to break out of more loops than exist, but it isn't
1127  * in the standard shell so we don't make it one here.
1128  */
1129
1130 int
1131 breakcmd(int argc, char **argv)
1132 {
1133         int n = argc > 1 ? number(argv[1]) : 1;
1134
1135         if (n > loopnest)
1136                 n = loopnest;
1137         if (n > 0) {
1138                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1139                 skipcount = n;
1140         }
1141         return 0;
1142 }
1143
1144 /*
1145  * The `command' command.
1146  */
1147 int
1148 commandcmd(int argc, char **argv)
1149 {
1150         const char *path;
1151         int ch;
1152         int cmd = -1;
1153
1154         path = bltinlookup("PATH", 1);
1155
1156         optind = optreset = 1;
1157         opterr = 0;
1158         while ((ch = getopt(argc, argv, "pvV")) != -1) {
1159                 switch (ch) {
1160                 case 'p':
1161                         path = _PATH_STDPATH;
1162                         break;
1163                 case 'v':
1164                         cmd = TYPECMD_SMALLV;
1165                         break;
1166                 case 'V':
1167                         cmd = TYPECMD_BIGV;
1168                         break;
1169                 case '?':
1170                 default:
1171                         error("unknown option: -%c", optopt);
1172                 }
1173         }
1174         argc -= optind;
1175         argv += optind;
1176
1177         if (cmd != -1) {
1178                 if (argc != 1)
1179                         error("wrong number of arguments");
1180                 return typecmd_impl(2, argv - 1, cmd, path);
1181         }
1182         if (argc != 0)
1183                 error("commandcmd bad call");
1184
1185         /*
1186          * Do nothing successfully if no command was specified;
1187          * ksh also does this.
1188          */
1189         return(0);
1190 }
1191
1192
1193 /*
1194  * The return command.
1195  */
1196
1197 int
1198 returncmd(int argc, char **argv)
1199 {
1200         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1201
1202         if (funcnest) {
1203                 evalskip = SKIPFUNC;
1204                 skipcount = 1;
1205         } else {
1206                 /* skip the rest of the file */
1207                 evalskip = SKIPFILE;
1208                 skipcount = 1;
1209         }
1210         return ret;
1211 }
1212
1213
1214 int
1215 falsecmd(int argc __unused, char **argv __unused)
1216 {
1217         return 1;
1218 }
1219
1220
1221 int
1222 truecmd(int argc __unused, char **argv __unused)
1223 {
1224         return 0;
1225 }
1226
1227
1228 int
1229 execcmd(int argc, char **argv)
1230 {
1231         /*
1232          * Because we have historically not supported any options,
1233          * only treat "--" specially.
1234          */
1235         if (argc > 1 && strcmp(argv[1], "--") == 0)
1236                 argc--, argv++;
1237         if (argc > 1) {
1238                 struct strlist *sp;
1239
1240                 iflag = 0;              /* exit on error */
1241                 mflag = 0;
1242                 optschanged();
1243                 for (sp = cmdenviron; sp ; sp = sp->next)
1244                         setvareq(sp->text, VEXPORT|VSTACK);
1245                 shellexec(argv + 1, environment(), pathval(), 0);
1246
1247         }
1248         return 0;
1249 }
1250
1251
1252 int
1253 timescmd(int argc __unused, char **argv __unused)
1254 {
1255         struct rusage ru;
1256         long shumins, shsmins, chumins, chsmins;
1257         double shusecs, shssecs, chusecs, chssecs;
1258
1259         if (getrusage(RUSAGE_SELF, &ru) < 0)
1260                 return 1;
1261         shumins = ru.ru_utime.tv_sec / 60;
1262         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1263         shsmins = ru.ru_stime.tv_sec / 60;
1264         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1265         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1266                 return 1;
1267         chumins = ru.ru_utime.tv_sec / 60;
1268         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1269         chsmins = ru.ru_stime.tv_sec / 60;
1270         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1271         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1272             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1273         return 0;
1274 }