sh: Expand aliases after assignments and redirections.
[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 1.105 2011/05/21 22:03:06 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         } else
425                 exitstatus = 0;
426 }
427
428
429 /*
430  * Evaluate a redirected compound command.
431  */
432
433 static void
434 evalredir(union node *n, int flags)
435 {
436         struct jmploc jmploc;
437         struct jmploc *savehandler;
438         volatile int in_redirect = 1;
439
440         expredir(n->nredir.redirect);
441         savehandler = handler;
442         if (setjmp(jmploc.loc)) {
443                 int e;
444
445                 handler = savehandler;
446                 e = exception;
447                 popredir();
448                 if (e == EXERROR || e == EXEXEC) {
449                         if (in_redirect) {
450                                 exitstatus = 2;
451                                 return;
452                         }
453                 }
454                 longjmp(handler->loc, 1);
455         } else {
456                 INTOFF;
457                 handler = &jmploc;
458                 redirect(n->nredir.redirect, REDIR_PUSH);
459                 in_redirect = 0;
460                 INTON;
461                 evaltree(n->nredir.n, flags);
462         }
463         INTOFF;
464         handler = savehandler;
465         popredir();
466         INTON;
467 }
468
469
470 /*
471  * Compute the names of the files in a redirection list.
472  */
473
474 static void
475 expredir(union node *n)
476 {
477         union node *redir;
478
479         for (redir = n ; redir ; redir = redir->nfile.next) {
480                 struct arglist fn;
481                 fn.lastp = &fn.list;
482                 oexitstatus = exitstatus;
483                 switch (redir->type) {
484                 case NFROM:
485                 case NTO:
486                 case NFROMTO:
487                 case NAPPEND:
488                 case NCLOBBER:
489                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
490                         redir->nfile.expfname = fn.list->text;
491                         break;
492                 case NFROMFD:
493                 case NTOFD:
494                         if (redir->ndup.vname) {
495                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
496                                 fixredir(redir, fn.list->text, 1);
497                         }
498                         break;
499                 }
500         }
501 }
502
503
504
505 /*
506  * Evaluate a pipeline.  All the processes in the pipeline are children
507  * of the process creating the pipeline.  (This differs from some versions
508  * of the shell, which make the last process in a pipeline the parent
509  * of all the rest.)
510  */
511
512 static void
513 evalpipe(union node *n)
514 {
515         struct job *jp;
516         struct nodelist *lp;
517         int pipelen;
518         int prevfd;
519         int pip[2];
520
521         TRACE(("evalpipe(%p) called\n", (void *)n));
522         pipelen = 0;
523         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
524                 pipelen++;
525         INTOFF;
526         jp = makejob(n, pipelen);
527         prevfd = -1;
528         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
529                 prehash(lp->n);
530                 pip[1] = -1;
531                 if (lp->next) {
532                         if (pipe(pip) < 0) {
533                                 if (prevfd >= 0)
534                                         close(prevfd);
535                                 error("Pipe call failed: %s", strerror(errno));
536                         }
537                 }
538                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
539                         INTON;
540                         if (prevfd > 0) {
541                                 dup2(prevfd, 0);
542                                 close(prevfd);
543                         }
544                         if (pip[1] >= 0) {
545                                 if (!(prevfd >= 0 && pip[0] == 0))
546                                         close(pip[0]);
547                                 if (pip[1] != 1) {
548                                         dup2(pip[1], 1);
549                                         close(pip[1]);
550                                 }
551                         }
552                         evaltree(lp->n, EV_EXIT);
553                 }
554                 if (prevfd >= 0)
555                         close(prevfd);
556                 prevfd = pip[0];
557                 if (pip[1] != -1)
558                         close(pip[1]);
559         }
560         INTON;
561         if (n->npipe.backgnd == 0) {
562                 INTOFF;
563                 exitstatus = waitforjob(jp, NULL);
564                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
565                 INTON;
566         } else
567                 exitstatus = 0;
568 }
569
570
571
572 static int
573 is_valid_fast_cmdsubst(union node *n)
574 {
575         union node *argp;
576
577         if (n->type != NCMD)
578                 return 0;
579         for (argp = n->ncmd.args ; argp ; argp = argp->narg.next)
580                 if (expandhassideeffects(argp->narg.text))
581                         return 0;
582         return 1;
583 }
584
585 /*
586  * Execute a command inside back quotes.  If it's a builtin command, we
587  * want to save its output in a block obtained from malloc.  Otherwise
588  * we fork off a subprocess and get the output of the command via a pipe.
589  * Should be called with interrupts off.
590  */
591
592 void
593 evalbackcmd(union node *n, struct backcmd *result)
594 {
595         int pip[2];
596         struct job *jp;
597         struct stackmark smark;         /* unnecessary */
598         struct jmploc jmploc;
599         struct jmploc *savehandler;
600
601         setstackmark(&smark);
602         result->fd = -1;
603         result->buf = NULL;
604         result->nleft = 0;
605         result->jp = NULL;
606         if (n == NULL) {
607                 exitstatus = 0;
608                 goto out;
609         }
610         if (is_valid_fast_cmdsubst(n)) {
611                 exitstatus = oexitstatus;
612                 savehandler = handler;
613                 if (setjmp(jmploc.loc)) {
614                         if (exception == EXERROR || exception == EXEXEC)
615                                 exitstatus = 2;
616                         else if (exception != 0) {
617                                 handler = savehandler;
618                                 longjmp(handler->loc, 1);
619                         }
620                 } else {
621                         handler = &jmploc;
622                         evalcommand(n, EV_BACKCMD, result);
623                 }
624                 handler = savehandler;
625         } else {
626                 exitstatus = 0;
627                 if (pipe(pip) < 0)
628                         error("Pipe call failed: %s", strerror(errno));
629                 jp = makejob(n, 1);
630                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
631                         FORCEINTON;
632                         close(pip[0]);
633                         if (pip[1] != 1) {
634                                 dup2(pip[1], 1);
635                                 close(pip[1]);
636                         }
637                         evaltree(n, EV_EXIT);
638                 }
639                 close(pip[1]);
640                 result->fd = pip[0];
641                 result->jp = jp;
642         }
643 out:
644         popstackmark(&smark);
645         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
646                 result->fd, result->buf, result->nleft, result->jp));
647 }
648
649 /*
650  * Check if a builtin can safely be executed in the same process,
651  * even though it should be in a subshell (command substitution).
652  * Note that jobid, jobs, times and trap can show information not
653  * available in a child process; this is deliberate.
654  * The arguments should already have been expanded.
655  */
656 static int
657 safe_builtin(int idx, int argc, char **argv)
658 {
659         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
660             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
661             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
662             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
663             idx == TYPECMD)
664                 return (1);
665         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
666             idx == UMASKCMD)
667                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
668         if (idx == SETCMD)
669                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
670                     argv[1][0] == '+') && argv[1][1] == 'o' &&
671                     argv[1][2] == '\0'));
672         return (0);
673 }
674
675 /*
676  * Execute a simple command.
677  * Note: This may or may not return if (flags & EV_EXIT).
678  */
679
680 static void
681 evalcommand(union node *cmd, int flgs, struct backcmd *backcmd)
682 {
683         struct stackmark smark;
684         union node *argp;
685         struct arglist arglist;
686         struct arglist varlist;
687         volatile int flags = flgs;
688         char **volatile argv;
689         volatile int argc;
690         char **envp;
691         int varflag;
692         struct strlist *sp;
693         int mode;
694         int pip[2];
695         struct cmdentry cmdentry;
696         struct job *volatile jp;
697         struct jmploc jmploc;
698         struct jmploc *savehandler;
699         const char *savecmdname;
700         struct shparam saveparam;
701         struct localvar *savelocalvars;
702         struct parsefile *savetopfile;
703         volatile int e;
704         char *volatile lastarg;
705         int realstatus;
706         volatile int do_clearcmdentry;
707         const char *path = pathval();
708
709         /* First expand the arguments. */
710         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
711         setstackmark(&smark);
712         arglist.lastp = &arglist.list;
713         varlist.lastp = &varlist.list;
714         varflag = 1;
715         jp = NULL;
716         do_clearcmdentry = 0;
717         oexitstatus = exitstatus;
718         exitstatus = 0;
719         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
720                 if (varflag && isassignment(argp->narg.text)) {
721                         expandarg(argp, &varlist, EXP_VARTILDE);
722                         continue;
723                 }
724                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
725                 varflag = 0;
726         }
727         *arglist.lastp = NULL;
728         *varlist.lastp = NULL;
729         expredir(cmd->ncmd.redirect);
730         argc = 0;
731         for (sp = arglist.list ; sp ; sp = sp->next)
732                 argc++;
733         /* Add one slot at the beginning for tryexec(). */
734         argv = stalloc(sizeof (char *) * (argc + 2));
735         argv++;
736
737         for (sp = arglist.list ; sp ; sp = sp->next) {
738                 TRACE(("evalcommand arg: %s\n", sp->text));
739                 *argv++ = sp->text;
740         }
741         *argv = NULL;
742         lastarg = NULL;
743         if (iflag && funcnest == 0 && argc > 0)
744                 lastarg = argv[-1];
745         argv -= argc;
746
747         /* Print the command if xflag is set. */
748         if (xflag) {
749                 char sep = 0;
750                 const char *p;
751                 out2str(ps4val());
752                 for (sp = varlist.list ; sp ; sp = sp->next) {
753                         if (sep != 0)
754                                 out2c(' ');
755                         p = strchr(sp->text, '=');
756                         if (p != NULL) {
757                                 p++;
758                                 outbin(sp->text, p - sp->text, out2);
759                                 out2qstr(p);
760                         } else
761                                 out2qstr(sp->text);
762                         sep = ' ';
763                 }
764                 for (sp = arglist.list ; sp ; sp = sp->next) {
765                         if (sep != 0)
766                                 out2c(' ');
767                         /* Disambiguate command looking like assignment. */
768                         if (sp == arglist.list &&
769                                         strchr(sp->text, '=') != NULL &&
770                                         strchr(sp->text, '\'') == NULL) {
771                                 out2c('\'');
772                                 out2str(sp->text);
773                                 out2c('\'');
774                         } else
775                                 out2qstr(sp->text);
776                         sep = ' ';
777                 }
778                 out2c('\n');
779                 flushout(&errout);
780         }
781
782         /* Now locate the command. */
783         if (argc == 0) {
784                 /* Variable assignment(s) without command */
785                 cmdentry.cmdtype = CMDBUILTIN;
786                 cmdentry.u.index = BLTINCMD;
787                 cmdentry.special = 0;
788         } else {
789                 static const char PATH[] = "PATH=";
790                 int cmd_flags = 0, bltinonly = 0;
791
792                 /*
793                  * Modify the command lookup path, if a PATH= assignment
794                  * is present
795                  */
796                 for (sp = varlist.list ; sp ; sp = sp->next)
797                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
798                                 path = sp->text + sizeof(PATH) - 1;
799                                 /*
800                                  * On `PATH=... command`, we need to make
801                                  * sure that the command isn't using the
802                                  * non-updated hash table of the outer PATH
803                                  * setting and we need to make sure that
804                                  * the hash table isn't filled with items
805                                  * from the temporary setting.
806                                  *
807                                  * It would be better to forbit using and
808                                  * updating the table while this command
809                                  * runs, by the command finding mechanism
810                                  * is heavily integrated with hash handling,
811                                  * so we just delete the hash before and after
812                                  * the command runs. Partly deleting like
813                                  * changepatch() does doesn't seem worth the
814                                  * bookinging effort, since most such runs add
815                                  * directories in front of the new PATH.
816                                  */
817                                 clearcmdentry();
818                                 do_clearcmdentry = 1;
819                         }
820
821                 for (;;) {
822                         if (bltinonly) {
823                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
824                                 if (cmdentry.u.index < 0) {
825                                         cmdentry.u.index = BLTINCMD;
826                                         argv--;
827                                         argc++;
828                                         break;
829                                 }
830                         } else
831                                 find_command(argv[0], &cmdentry, cmd_flags, path);
832                         /* implement the bltin and command builtins here */
833                         if (cmdentry.cmdtype != CMDBUILTIN)
834                                 break;
835                         if (cmdentry.u.index == BLTINCMD) {
836                                 if (argc == 1)
837                                         break;
838                                 argv++;
839                                 argc--;
840                                 bltinonly = 1;
841                         } else if (cmdentry.u.index == COMMANDCMD) {
842                                 if (argc == 1)
843                                         break;
844                                 if (!strcmp(argv[1], "-p")) {
845                                         if (argc == 2)
846                                                 break;
847                                         if (argv[2][0] == '-') {
848                                                 if (strcmp(argv[2], "--"))
849                                                         break;
850                                                 if (argc == 3)
851                                                         break;
852                                                 argv += 3;
853                                                 argc -= 3;
854                                         } else {
855                                                 argv += 2;
856                                                 argc -= 2;
857                                         }
858                                         path = _PATH_STDPATH;
859                                         clearcmdentry();
860                                         do_clearcmdentry = 1;
861                                 } else if (!strcmp(argv[1], "--")) {
862                                         if (argc == 2)
863                                                 break;
864                                         argv += 2;
865                                         argc -= 2;
866                                 } else if (argv[1][0] == '-')
867                                         break;
868                                 else {
869                                         argv++;
870                                         argc--;
871                                 }
872                                 cmd_flags |= DO_NOFUNC;
873                                 bltinonly = 0;
874                         } else
875                                 break;
876                 }
877                 /*
878                  * Special builtins lose their special properties when
879                  * called via 'command'.
880                  */
881                 if (cmd_flags & DO_NOFUNC)
882                         cmdentry.special = 0;
883         }
884
885         /* Fork off a child process if necessary. */
886         if (cmd->ncmd.backgnd
887          || ((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
888             && ((flags & EV_EXIT) == 0 || have_traps()))
889          || ((flags & EV_BACKCMD) != 0
890             && (cmdentry.cmdtype != CMDBUILTIN ||
891                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
892                 jp = makejob(cmd, 1);
893                 mode = cmd->ncmd.backgnd;
894                 if (flags & EV_BACKCMD) {
895                         mode = FORK_NOJOB;
896                         if (pipe(pip) < 0)
897                                 error("Pipe call failed: %s", strerror(errno));
898                 }
899                 if (forkshell(jp, cmd, mode) != 0)
900                         goto parent;    /* at end of routine */
901                 if (flags & EV_BACKCMD) {
902                         FORCEINTON;
903                         close(pip[0]);
904                         if (pip[1] != 1) {
905                                 dup2(pip[1], 1);
906                                 close(pip[1]);
907                         }
908                 }
909                 flags |= EV_EXIT;
910         }
911
912         /* This is the child process if a fork occurred. */
913         /* Execute the command. */
914         if (cmdentry.cmdtype == CMDFUNCTION) {
915 #ifdef DEBUG
916                 trputs("Shell function:  ");  trargs(argv);
917 #endif
918                 saveparam = shellparam;
919                 shellparam.malloc = 0;
920                 shellparam.reset = 1;
921                 shellparam.nparam = argc - 1;
922                 shellparam.p = argv + 1;
923                 shellparam.optnext = NULL;
924                 INTOFF;
925                 savelocalvars = localvars;
926                 localvars = NULL;
927                 reffunc(cmdentry.u.func);
928                 savehandler = handler;
929                 if (setjmp(jmploc.loc)) {
930                         freeparam(&shellparam);
931                         shellparam = saveparam;
932                         popredir();
933                         unreffunc(cmdentry.u.func);
934                         poplocalvars();
935                         localvars = savelocalvars;
936                         funcnest--;
937                         handler = savehandler;
938                         longjmp(handler->loc, 1);
939                 }
940                 handler = &jmploc;
941                 funcnest++;
942                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
943                 INTON;
944                 for (sp = varlist.list ; sp ; sp = sp->next)
945                         mklocal(sp->text);
946                 exitstatus = oexitstatus;
947                 evaltree(getfuncnode(cmdentry.u.func),
948                     flags & (EV_TESTED | EV_EXIT));
949                 INTOFF;
950                 unreffunc(cmdentry.u.func);
951                 poplocalvars();
952                 localvars = savelocalvars;
953                 freeparam(&shellparam);
954                 shellparam = saveparam;
955                 handler = savehandler;
956                 funcnest--;
957                 popredir();
958                 INTON;
959                 if (evalskip == SKIPFUNC) {
960                         evalskip = 0;
961                         skipcount = 0;
962                 }
963                 if (jp)
964                         exitshell(exitstatus);
965         } else if (cmdentry.cmdtype == CMDBUILTIN) {
966 #ifdef DEBUG
967                 trputs("builtin command:  ");  trargs(argv);
968 #endif
969                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
970                 if (flags == EV_BACKCMD) {
971                         memout.nleft = 0;
972                         memout.nextc = memout.buf;
973                         memout.bufsize = 64;
974                         mode |= REDIR_BACKQ;
975                         cmdentry.special = 0;
976                 }
977                 savecmdname = commandname;
978                 savetopfile = getcurrentfile();
979                 cmdenviron = varlist.list;
980                 e = -1;
981                 savehandler = handler;
982                 if (setjmp(jmploc.loc)) {
983                         e = exception;
984                         if (e == EXINT)
985                                 exitstatus = SIGINT+128;
986                         else if (e != EXEXIT)
987                                 exitstatus = 2;
988                         goto cmddone;
989                 }
990                 handler = &jmploc;
991                 redirect(cmd->ncmd.redirect, mode);
992                 /*
993                  * If there is no command word, redirection errors should
994                  * not be fatal but assignment errors should.
995                  */
996                 if (argc == 0 && !(flags & EV_BACKCMD))
997                         cmdentry.special = 1;
998                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
999                 if (argc > 0)
1000                         bltinsetlocale();
1001                 commandname = argv[0];
1002                 argptr = argv + 1;
1003                 nextopt_optptr = NULL;          /* initialize nextopt */
1004                 builtin_flags = flags;
1005                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1006                 flushall();
1007 cmddone:
1008                 if (argc > 0)
1009                         bltinunsetlocale();
1010                 cmdenviron = NULL;
1011                 out1 = &output;
1012                 out2 = &errout;
1013                 freestdout();
1014                 handler = savehandler;
1015                 commandname = savecmdname;
1016                 if (jp)
1017                         exitshell(exitstatus);
1018                 if (flags == EV_BACKCMD) {
1019                         backcmd->buf = memout.buf;
1020                         backcmd->nleft = memout.nextc - memout.buf;
1021                         memout.buf = NULL;
1022                 }
1023                 if (cmdentry.u.index != EXECCMD)
1024                         popredir();
1025                 if (e != -1) {
1026                         if ((e != EXERROR && e != EXEXEC)
1027                             || cmdentry.special)
1028                                 exraise(e);
1029                         popfilesupto(savetopfile);
1030                         if (flags != EV_BACKCMD)
1031                                 FORCEINTON;
1032                 }
1033         } else {
1034 #ifdef DEBUG
1035                 trputs("normal command:  ");  trargs(argv);
1036 #endif
1037                 redirect(cmd->ncmd.redirect, 0);
1038                 for (sp = varlist.list ; sp ; sp = sp->next)
1039                         setvareq(sp->text, VEXPORT|VSTACK);
1040                 envp = environment();
1041                 shellexec(argv, envp, path, cmdentry.u.index);
1042                 /*NOTREACHED*/
1043         }
1044         goto out;
1045
1046 parent: /* parent process gets here (if we forked) */
1047         if (mode == FORK_FG) {  /* argument to fork */
1048                 INTOFF;
1049                 exitstatus = waitforjob(jp, &realstatus);
1050                 INTON;
1051                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1052                         evalskip = SKIPBREAK;
1053                         skipcount = loopnest;
1054                 }
1055         } else if (mode == FORK_NOJOB) {
1056                 backcmd->fd = pip[0];
1057                 close(pip[1]);
1058                 backcmd->jp = jp;
1059         } else
1060                 exitstatus = 0;
1061
1062 out:
1063         if (lastarg)
1064                 setvar("_", lastarg, 0);
1065         if (do_clearcmdentry)
1066                 clearcmdentry();
1067         popstackmark(&smark);
1068 }
1069
1070
1071
1072 /*
1073  * Search for a command.  This is called before we fork so that the
1074  * location of the command will be available in the parent as well as
1075  * the child.  The check for "goodname" is an overly conservative
1076  * check that the name will not be subject to expansion.
1077  */
1078
1079 static void
1080 prehash(union node *n)
1081 {
1082         struct cmdentry entry;
1083
1084         if (n && n->type == NCMD && n->ncmd.args)
1085                 if (goodname(n->ncmd.args->narg.text))
1086                         find_command(n->ncmd.args->narg.text, &entry, 0,
1087                                      pathval());
1088 }
1089
1090
1091
1092 /*
1093  * Builtin commands.  Builtin commands whose functions are closely
1094  * tied to evaluation are implemented here.
1095  */
1096
1097 /*
1098  * No command given, a bltin command with no arguments, or a bltin command
1099  * with an invalid name.
1100  */
1101
1102 int
1103 bltincmd(int argc, char **argv)
1104 {
1105         if (argc > 1) {
1106                 out2fmt_flush("%s: not found\n", argv[1]);
1107                 return 127;
1108         }
1109         /*
1110          * Preserve exitstatus of a previous possible redirection
1111          * as POSIX mandates
1112          */
1113         return exitstatus;
1114 }
1115
1116
1117 /*
1118  * Handle break and continue commands.  Break, continue, and return are
1119  * all handled by setting the evalskip flag.  The evaluation routines
1120  * above all check this flag, and if it is set they start skipping
1121  * commands rather than executing them.  The variable skipcount is
1122  * the number of loops to break/continue, or the number of function
1123  * levels to return.  (The latter is always 1.)  It should probably
1124  * be an error to break out of more loops than exist, but it isn't
1125  * in the standard shell so we don't make it one here.
1126  */
1127
1128 int
1129 breakcmd(int argc, char **argv)
1130 {
1131         int n = argc > 1 ? number(argv[1]) : 1;
1132
1133         if (n > loopnest)
1134                 n = loopnest;
1135         if (n > 0) {
1136                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1137                 skipcount = n;
1138         }
1139         return 0;
1140 }
1141
1142 /*
1143  * The `command' command.
1144  */
1145 int
1146 commandcmd(int argc, char **argv)
1147 {
1148         const char *path;
1149         int ch;
1150         int cmd = -1;
1151
1152         path = bltinlookup("PATH", 1);
1153
1154         optind = optreset = 1;
1155         opterr = 0;
1156         while ((ch = getopt(argc, argv, "pvV")) != -1) {
1157                 switch (ch) {
1158                 case 'p':
1159                         path = _PATH_STDPATH;
1160                         break;
1161                 case 'v':
1162                         cmd = TYPECMD_SMALLV;
1163                         break;
1164                 case 'V':
1165                         cmd = TYPECMD_BIGV;
1166                         break;
1167                 case '?':
1168                 default:
1169                         error("unknown option: -%c", optopt);
1170                 }
1171         }
1172         argc -= optind;
1173         argv += optind;
1174
1175         if (cmd != -1) {
1176                 if (argc != 1)
1177                         error("wrong number of arguments");
1178                 return typecmd_impl(2, argv - 1, cmd, path);
1179         }
1180         if (argc != 0)
1181                 error("commandcmd bad call");
1182
1183         /*
1184          * Do nothing successfully if no command was specified;
1185          * ksh also does this.
1186          */
1187         return(0);
1188 }
1189
1190
1191 /*
1192  * The return command.
1193  */
1194
1195 int
1196 returncmd(int argc, char **argv)
1197 {
1198         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1199
1200         if (funcnest) {
1201                 evalskip = SKIPFUNC;
1202                 skipcount = 1;
1203         } else {
1204                 /* skip the rest of the file */
1205                 evalskip = SKIPFILE;
1206                 skipcount = 1;
1207         }
1208         return ret;
1209 }
1210
1211
1212 int
1213 falsecmd(int argc __unused, char **argv __unused)
1214 {
1215         return 1;
1216 }
1217
1218
1219 int
1220 truecmd(int argc __unused, char **argv __unused)
1221 {
1222         return 0;
1223 }
1224
1225
1226 int
1227 execcmd(int argc, char **argv)
1228 {
1229         /*
1230          * Because we have historically not supported any options,
1231          * only treat "--" specially.
1232          */
1233         if (argc > 1 && strcmp(argv[1], "--") == 0)
1234                 argc--, argv++;
1235         if (argc > 1) {
1236                 struct strlist *sp;
1237
1238                 iflag = 0;              /* exit on error */
1239                 mflag = 0;
1240                 optschanged();
1241                 for (sp = cmdenviron; sp ; sp = sp->next)
1242                         setvareq(sp->text, VEXPORT|VSTACK);
1243                 shellexec(argv + 1, environment(), pathval(), 0);
1244
1245         }
1246         return 0;
1247 }
1248
1249
1250 int
1251 timescmd(int argc __unused, char **argv __unused)
1252 {
1253         struct rusage ru;
1254         long shumins, shsmins, chumins, chsmins;
1255         double shusecs, shssecs, chusecs, chssecs;
1256
1257         if (getrusage(RUSAGE_SELF, &ru) < 0)
1258                 return 1;
1259         shumins = ru.ru_utime.tv_sec / 60;
1260         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1261         shsmins = ru.ru_stime.tv_sec / 60;
1262         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1263         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1264                 return 1;
1265         chumins = ru.ru_utime.tv_sec / 60;
1266         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1267         chsmins = ru.ru_stime.tv_sec / 60;
1268         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1269         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1270             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1271         return 0;
1272 }