sh: Save/restore changed variables in optimized command substitution.
[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 1.109 2011/06/12 23:06:04 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 && !nflag) {
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         oexitstatus = exitstatus;
414         expredir(n->nredir.redirect);
415         if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
416             forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
417                 if (backgnd)
418                         flags &=~ EV_TESTED;
419                 redirect(n->nredir.redirect, 0);
420                 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
421         } else if (!backgnd) {
422                 INTOFF;
423                 exitstatus = waitforjob(jp, NULL);
424                 INTON;
425         } else
426                 exitstatus = 0;
427 }
428
429
430 /*
431  * Evaluate a redirected compound command.
432  */
433
434 static void
435 evalredir(union node *n, int flags)
436 {
437         struct jmploc jmploc;
438         struct jmploc *savehandler;
439         volatile int in_redirect = 1;
440
441         oexitstatus = exitstatus;
442         expredir(n->nredir.redirect);
443         savehandler = handler;
444         if (setjmp(jmploc.loc)) {
445                 int e;
446
447                 handler = savehandler;
448                 e = exception;
449                 popredir();
450                 if (e == EXERROR || e == EXEXEC) {
451                         if (in_redirect) {
452                                 exitstatus = 2;
453                                 return;
454                         }
455                 }
456                 longjmp(handler->loc, 1);
457         } else {
458                 INTOFF;
459                 handler = &jmploc;
460                 redirect(n->nredir.redirect, REDIR_PUSH);
461                 in_redirect = 0;
462                 INTON;
463                 evaltree(n->nredir.n, flags);
464         }
465         INTOFF;
466         handler = savehandler;
467         popredir();
468         INTON;
469 }
470
471
472 /*
473  * Compute the names of the files in a redirection list.
474  */
475
476 static void
477 expredir(union node *n)
478 {
479         union node *redir;
480
481         for (redir = n ; redir ; redir = redir->nfile.next) {
482                 struct arglist fn;
483                 fn.lastp = &fn.list;
484                 switch (redir->type) {
485                 case NFROM:
486                 case NTO:
487                 case NFROMTO:
488                 case NAPPEND:
489                 case NCLOBBER:
490                         expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
491                         redir->nfile.expfname = fn.list->text;
492                         break;
493                 case NFROMFD:
494                 case NTOFD:
495                         if (redir->ndup.vname) {
496                                 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
497                                 fixredir(redir, fn.list->text, 1);
498                         }
499                         break;
500                 }
501         }
502 }
503
504
505
506 /*
507  * Evaluate a pipeline.  All the processes in the pipeline are children
508  * of the process creating the pipeline.  (This differs from some versions
509  * of the shell, which make the last process in a pipeline the parent
510  * of all the rest.)
511  */
512
513 static void
514 evalpipe(union node *n)
515 {
516         struct job *jp;
517         struct nodelist *lp;
518         int pipelen;
519         int prevfd;
520         int pip[2];
521
522         TRACE(("evalpipe(%p) called\n", (void *)n));
523         pipelen = 0;
524         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
525                 pipelen++;
526         INTOFF;
527         jp = makejob(n, pipelen);
528         prevfd = -1;
529         for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
530                 prehash(lp->n);
531                 pip[1] = -1;
532                 if (lp->next) {
533                         if (pipe(pip) < 0) {
534                                 if (prevfd >= 0)
535                                         close(prevfd);
536                                 error("Pipe call failed: %s", strerror(errno));
537                         }
538                 }
539                 if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
540                         INTON;
541                         if (prevfd > 0) {
542                                 dup2(prevfd, 0);
543                                 close(prevfd);
544                         }
545                         if (pip[1] >= 0) {
546                                 if (!(prevfd >= 0 && pip[0] == 0))
547                                         close(pip[0]);
548                                 if (pip[1] != 1) {
549                                         dup2(pip[1], 1);
550                                         close(pip[1]);
551                                 }
552                         }
553                         evaltree(lp->n, EV_EXIT);
554                 }
555                 if (prevfd >= 0)
556                         close(prevfd);
557                 prevfd = pip[0];
558                 if (pip[1] != -1)
559                         close(pip[1]);
560         }
561         INTON;
562         if (n->npipe.backgnd == 0) {
563                 INTOFF;
564                 exitstatus = waitforjob(jp, NULL);
565                 TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
566                 INTON;
567         } else
568                 exitstatus = 0;
569 }
570
571
572
573 static int
574 is_valid_fast_cmdsubst(union node *n)
575 {
576
577         return (n->type == NCMD);
578 }
579
580 /*
581  * Execute a command inside back quotes.  If it's a builtin command, we
582  * want to save its output in a block obtained from malloc.  Otherwise
583  * we fork off a subprocess and get the output of the command via a pipe.
584  * Should be called with interrupts off.
585  */
586
587 void
588 evalbackcmd(union node *n, struct backcmd *result)
589 {
590         int pip[2];
591         struct job *jp;
592         struct stackmark smark;         /* unnecessary */
593         struct jmploc jmploc;
594         struct jmploc *savehandler;
595         struct localvar *savelocalvars;
596
597         setstackmark(&smark);
598         result->fd = -1;
599         result->buf = NULL;
600         result->nleft = 0;
601         result->jp = NULL;
602         if (n == NULL) {
603                 exitstatus = 0;
604                 goto out;
605         }
606         if (is_valid_fast_cmdsubst(n)) {
607                 exitstatus = oexitstatus;
608                 savelocalvars = localvars;
609                 localvars = NULL;
610                 forcelocal++;
611                 savehandler = handler;
612                 if (setjmp(jmploc.loc)) {
613                         if (exception == EXERROR || exception == EXEXEC)
614                                 exitstatus = 2;
615                         else if (exception != 0) {
616                                 handler = savehandler;
617                                 forcelocal--;
618                                 poplocalvars();
619                                 localvars = savelocalvars;
620                                 longjmp(handler->loc, 1);
621                         }
622                 } else {
623                         handler = &jmploc;
624                         evalcommand(n, EV_BACKCMD, result);
625                 }
626                 handler = savehandler;
627                 forcelocal--;
628                 poplocalvars();
629                 localvars = savelocalvars;
630         } else {
631                 exitstatus = 0;
632                 if (pipe(pip) < 0)
633                         error("Pipe call failed: %s", strerror(errno));
634                 jp = makejob(n, 1);
635                 if (forkshell(jp, n, FORK_NOJOB) == 0) {
636                         FORCEINTON;
637                         close(pip[0]);
638                         if (pip[1] != 1) {
639                                 dup2(pip[1], 1);
640                                 close(pip[1]);
641                         }
642                         evaltree(n, EV_EXIT);
643                 }
644                 close(pip[1]);
645                 result->fd = pip[0];
646                 result->jp = jp;
647         }
648 out:
649         popstackmark(&smark);
650         TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
651                 result->fd, result->buf, result->nleft, result->jp));
652 }
653
654 /*
655  * Check if a builtin can safely be executed in the same process,
656  * even though it should be in a subshell (command substitution).
657  * Note that jobid, jobs, times and trap can show information not
658  * available in a child process; this is deliberate.
659  * The arguments should already have been expanded.
660  */
661 static int
662 safe_builtin(int idx, int argc, char **argv)
663 {
664         if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
665             idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
666             idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
667             idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
668             idx == TYPECMD)
669                 return (1);
670         if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
671             idx == UMASKCMD)
672                 return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
673         if (idx == SETCMD)
674                 return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
675                     argv[1][0] == '+') && argv[1][1] == 'o' &&
676                     argv[1][2] == '\0'));
677         return (0);
678 }
679
680 /*
681  * Execute a simple command.
682  * Note: This may or may not return if (flags & EV_EXIT).
683  */
684
685 static void
686 evalcommand(union node *cmd, int flgs, struct backcmd *backcmd)
687 {
688         struct stackmark smark;
689         union node *argp;
690         struct arglist arglist;
691         struct arglist varlist;
692         volatile int flags = flgs;
693         char **volatile argv;
694         volatile int argc;
695         char **envp;
696         int varflag;
697         struct strlist *sp;
698         int mode;
699         int pip[2];
700         struct cmdentry cmdentry;
701         struct job *volatile jp;
702         struct jmploc jmploc;
703         struct jmploc *savehandler;
704         const char *savecmdname;
705         struct shparam saveparam;
706         struct localvar *savelocalvars;
707         struct parsefile *savetopfile;
708         volatile int e;
709         char *volatile lastarg;
710         int realstatus;
711         volatile int do_clearcmdentry;
712         const char *path = pathval();
713
714         /* First expand the arguments. */
715         TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
716         setstackmark(&smark);
717         arglist.lastp = &arglist.list;
718         varlist.lastp = &varlist.list;
719         varflag = 1;
720         jp = NULL;
721         do_clearcmdentry = 0;
722         oexitstatus = exitstatus;
723         exitstatus = 0;
724         for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
725                 if (varflag && isassignment(argp->narg.text)) {
726                         expandarg(argp, &varlist, EXP_VARTILDE);
727                         continue;
728                 }
729                 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
730                 varflag = 0;
731         }
732         *arglist.lastp = NULL;
733         *varlist.lastp = NULL;
734         expredir(cmd->ncmd.redirect);
735         argc = 0;
736         for (sp = arglist.list ; sp ; sp = sp->next)
737                 argc++;
738         /* Add one slot at the beginning for tryexec(). */
739         argv = stalloc(sizeof (char *) * (argc + 2));
740         argv++;
741
742         for (sp = arglist.list ; sp ; sp = sp->next) {
743                 TRACE(("evalcommand arg: %s\n", sp->text));
744                 *argv++ = sp->text;
745         }
746         *argv = NULL;
747         lastarg = NULL;
748         if (iflag && funcnest == 0 && argc > 0)
749                 lastarg = argv[-1];
750         argv -= argc;
751
752         /* Print the command if xflag is set. */
753         if (xflag) {
754                 char sep = 0;
755                 const char *p, *ps4;
756                 ps4 = expandstr(ps4val());
757                 out2str(ps4 != NULL ? ps4 : ps4val());
758                 for (sp = varlist.list ; sp ; sp = sp->next) {
759                         if (sep != 0)
760                                 out2c(' ');
761                         p = strchr(sp->text, '=');
762                         if (p != NULL) {
763                                 p++;
764                                 outbin(sp->text, p - sp->text, out2);
765                                 out2qstr(p);
766                         } else
767                                 out2qstr(sp->text);
768                         sep = ' ';
769                 }
770                 for (sp = arglist.list ; sp ; sp = sp->next) {
771                         if (sep != 0)
772                                 out2c(' ');
773                         /* Disambiguate command looking like assignment. */
774                         if (sp == arglist.list &&
775                                         strchr(sp->text, '=') != NULL &&
776                                         strchr(sp->text, '\'') == NULL) {
777                                 out2c('\'');
778                                 out2str(sp->text);
779                                 out2c('\'');
780                         } else
781                                 out2qstr(sp->text);
782                         sep = ' ';
783                 }
784                 out2c('\n');
785                 flushout(&errout);
786         }
787
788         /* Now locate the command. */
789         if (argc == 0) {
790                 /* Variable assignment(s) without command */
791                 cmdentry.cmdtype = CMDBUILTIN;
792                 cmdentry.u.index = BLTINCMD;
793                 cmdentry.special = 0;
794         } else {
795                 static const char PATH[] = "PATH=";
796                 int cmd_flags = 0, bltinonly = 0;
797
798                 /*
799                  * Modify the command lookup path, if a PATH= assignment
800                  * is present
801                  */
802                 for (sp = varlist.list ; sp ; sp = sp->next)
803                         if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
804                                 path = sp->text + sizeof(PATH) - 1;
805                                 /*
806                                  * On `PATH=... command`, we need to make
807                                  * sure that the command isn't using the
808                                  * non-updated hash table of the outer PATH
809                                  * setting and we need to make sure that
810                                  * the hash table isn't filled with items
811                                  * from the temporary setting.
812                                  *
813                                  * It would be better to forbit using and
814                                  * updating the table while this command
815                                  * runs, by the command finding mechanism
816                                  * is heavily integrated with hash handling,
817                                  * so we just delete the hash before and after
818                                  * the command runs. Partly deleting like
819                                  * changepatch() does doesn't seem worth the
820                                  * bookinging effort, since most such runs add
821                                  * directories in front of the new PATH.
822                                  */
823                                 clearcmdentry();
824                                 do_clearcmdentry = 1;
825                         }
826
827                 for (;;) {
828                         if (bltinonly) {
829                                 cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
830                                 if (cmdentry.u.index < 0) {
831                                         cmdentry.u.index = BLTINCMD;
832                                         argv--;
833                                         argc++;
834                                         break;
835                                 }
836                         } else
837                                 find_command(argv[0], &cmdentry, cmd_flags, path);
838                         /* implement the bltin and command builtins here */
839                         if (cmdentry.cmdtype != CMDBUILTIN)
840                                 break;
841                         if (cmdentry.u.index == BLTINCMD) {
842                                 if (argc == 1)
843                                         break;
844                                 argv++;
845                                 argc--;
846                                 bltinonly = 1;
847                         } else if (cmdentry.u.index == COMMANDCMD) {
848                                 if (argc == 1)
849                                         break;
850                                 if (!strcmp(argv[1], "-p")) {
851                                         if (argc == 2)
852                                                 break;
853                                         if (argv[2][0] == '-') {
854                                                 if (strcmp(argv[2], "--"))
855                                                         break;
856                                                 if (argc == 3)
857                                                         break;
858                                                 argv += 3;
859                                                 argc -= 3;
860                                         } else {
861                                                 argv += 2;
862                                                 argc -= 2;
863                                         }
864                                         path = _PATH_STDPATH;
865                                         clearcmdentry();
866                                         do_clearcmdentry = 1;
867                                 } else if (!strcmp(argv[1], "--")) {
868                                         if (argc == 2)
869                                                 break;
870                                         argv += 2;
871                                         argc -= 2;
872                                 } else if (argv[1][0] == '-')
873                                         break;
874                                 else {
875                                         argv++;
876                                         argc--;
877                                 }
878                                 cmd_flags |= DO_NOFUNC;
879                                 bltinonly = 0;
880                         } else
881                                 break;
882                 }
883                 /*
884                  * Special builtins lose their special properties when
885                  * called via 'command'.
886                  */
887                 if (cmd_flags & DO_NOFUNC)
888                         cmdentry.special = 0;
889         }
890
891         /* Fork off a child process if necessary. */
892         if (cmd->ncmd.backgnd
893          || ((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
894             && ((flags & EV_EXIT) == 0 || have_traps()))
895          || ((flags & EV_BACKCMD) != 0
896             && (cmdentry.cmdtype != CMDBUILTIN ||
897                  !safe_builtin(cmdentry.u.index, argc, argv)))) {
898                 jp = makejob(cmd, 1);
899                 mode = cmd->ncmd.backgnd;
900                 if (flags & EV_BACKCMD) {
901                         mode = FORK_NOJOB;
902                         if (pipe(pip) < 0)
903                                 error("Pipe call failed: %s", strerror(errno));
904                 }
905                 if (forkshell(jp, cmd, mode) != 0)
906                         goto parent;    /* at end of routine */
907                 if (flags & EV_BACKCMD) {
908                         FORCEINTON;
909                         close(pip[0]);
910                         if (pip[1] != 1) {
911                                 dup2(pip[1], 1);
912                                 close(pip[1]);
913                         }
914                 }
915                 flags |= EV_EXIT;
916         }
917
918         /* This is the child process if a fork occurred. */
919         /* Execute the command. */
920         if (cmdentry.cmdtype == CMDFUNCTION) {
921 #ifdef DEBUG
922                 trputs("Shell function:  ");  trargs(argv);
923 #endif
924                 saveparam = shellparam;
925                 shellparam.malloc = 0;
926                 shellparam.reset = 1;
927                 shellparam.nparam = argc - 1;
928                 shellparam.p = argv + 1;
929                 shellparam.optnext = NULL;
930                 INTOFF;
931                 savelocalvars = localvars;
932                 localvars = NULL;
933                 reffunc(cmdentry.u.func);
934                 savehandler = handler;
935                 if (setjmp(jmploc.loc)) {
936                         freeparam(&shellparam);
937                         shellparam = saveparam;
938                         popredir();
939                         unreffunc(cmdentry.u.func);
940                         poplocalvars();
941                         localvars = savelocalvars;
942                         funcnest--;
943                         handler = savehandler;
944                         longjmp(handler->loc, 1);
945                 }
946                 handler = &jmploc;
947                 funcnest++;
948                 redirect(cmd->ncmd.redirect, REDIR_PUSH);
949                 INTON;
950                 for (sp = varlist.list ; sp ; sp = sp->next)
951                         mklocal(sp->text);
952                 exitstatus = oexitstatus;
953                 evaltree(getfuncnode(cmdentry.u.func),
954                     flags & (EV_TESTED | EV_EXIT));
955                 INTOFF;
956                 unreffunc(cmdentry.u.func);
957                 poplocalvars();
958                 localvars = savelocalvars;
959                 freeparam(&shellparam);
960                 shellparam = saveparam;
961                 handler = savehandler;
962                 funcnest--;
963                 popredir();
964                 INTON;
965                 if (evalskip == SKIPFUNC) {
966                         evalskip = 0;
967                         skipcount = 0;
968                 }
969                 if (jp)
970                         exitshell(exitstatus);
971         } else if (cmdentry.cmdtype == CMDBUILTIN) {
972 #ifdef DEBUG
973                 trputs("builtin command:  ");  trargs(argv);
974 #endif
975                 mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
976                 if (flags == EV_BACKCMD) {
977                         memout.nleft = 0;
978                         memout.nextc = memout.buf;
979                         memout.bufsize = 64;
980                         mode |= REDIR_BACKQ;
981                         cmdentry.special = 0;
982                 }
983                 savecmdname = commandname;
984                 savetopfile = getcurrentfile();
985                 cmdenviron = varlist.list;
986                 e = -1;
987                 savehandler = handler;
988                 if (setjmp(jmploc.loc)) {
989                         e = exception;
990                         if (e == EXINT)
991                                 exitstatus = SIGINT+128;
992                         else if (e != EXEXIT)
993                                 exitstatus = 2;
994                         goto cmddone;
995                 }
996                 handler = &jmploc;
997                 redirect(cmd->ncmd.redirect, mode);
998                 /*
999                  * If there is no command word, redirection errors should
1000                  * not be fatal but assignment errors should.
1001                  */
1002                 if (argc == 0 && !(flags & EV_BACKCMD))
1003                         cmdentry.special = 1;
1004                 listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1005                 if (argc > 0)
1006                         bltinsetlocale();
1007                 commandname = argv[0];
1008                 argptr = argv + 1;
1009                 nextopt_optptr = NULL;          /* initialize nextopt */
1010                 builtin_flags = flags;
1011                 exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1012                 flushall();
1013 cmddone:
1014                 if (argc > 0)
1015                         bltinunsetlocale();
1016                 cmdenviron = NULL;
1017                 out1 = &output;
1018                 out2 = &errout;
1019                 freestdout();
1020                 handler = savehandler;
1021                 commandname = savecmdname;
1022                 if (jp)
1023                         exitshell(exitstatus);
1024                 if (flags == EV_BACKCMD) {
1025                         backcmd->buf = memout.buf;
1026                         backcmd->nleft = memout.nextc - memout.buf;
1027                         memout.buf = NULL;
1028                 }
1029                 if (cmdentry.u.index != EXECCMD)
1030                         popredir();
1031                 if (e != -1) {
1032                         if ((e != EXERROR && e != EXEXEC)
1033                             || cmdentry.special)
1034                                 exraise(e);
1035                         popfilesupto(savetopfile);
1036                         if (flags != EV_BACKCMD)
1037                                 FORCEINTON;
1038                 }
1039         } else {
1040 #ifdef DEBUG
1041                 trputs("normal command:  ");  trargs(argv);
1042 #endif
1043                 redirect(cmd->ncmd.redirect, 0);
1044                 for (sp = varlist.list ; sp ; sp = sp->next)
1045                         setvareq(sp->text, VEXPORT|VSTACK);
1046                 envp = environment();
1047                 shellexec(argv, envp, path, cmdentry.u.index);
1048                 /*NOTREACHED*/
1049         }
1050         goto out;
1051
1052 parent: /* parent process gets here (if we forked) */
1053         if (mode == FORK_FG) {  /* argument to fork */
1054                 INTOFF;
1055                 exitstatus = waitforjob(jp, &realstatus);
1056                 INTON;
1057                 if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1058                         evalskip = SKIPBREAK;
1059                         skipcount = loopnest;
1060                 }
1061         } else if (mode == FORK_NOJOB) {
1062                 backcmd->fd = pip[0];
1063                 close(pip[1]);
1064                 backcmd->jp = jp;
1065         } else
1066                 exitstatus = 0;
1067
1068 out:
1069         if (lastarg)
1070                 setvar("_", lastarg, 0);
1071         if (do_clearcmdentry)
1072                 clearcmdentry();
1073         popstackmark(&smark);
1074 }
1075
1076
1077
1078 /*
1079  * Search for a command.  This is called before we fork so that the
1080  * location of the command will be available in the parent as well as
1081  * the child.  The check for "goodname" is an overly conservative
1082  * check that the name will not be subject to expansion.
1083  */
1084
1085 static void
1086 prehash(union node *n)
1087 {
1088         struct cmdentry entry;
1089
1090         if (n && n->type == NCMD && n->ncmd.args)
1091                 if (goodname(n->ncmd.args->narg.text))
1092                         find_command(n->ncmd.args->narg.text, &entry, 0,
1093                                      pathval());
1094 }
1095
1096
1097
1098 /*
1099  * Builtin commands.  Builtin commands whose functions are closely
1100  * tied to evaluation are implemented here.
1101  */
1102
1103 /*
1104  * No command given, a bltin command with no arguments, or a bltin command
1105  * with an invalid name.
1106  */
1107
1108 int
1109 bltincmd(int argc, char **argv)
1110 {
1111         if (argc > 1) {
1112                 out2fmt_flush("%s: not found\n", argv[1]);
1113                 return 127;
1114         }
1115         /*
1116          * Preserve exitstatus of a previous possible redirection
1117          * as POSIX mandates
1118          */
1119         return exitstatus;
1120 }
1121
1122
1123 /*
1124  * Handle break and continue commands.  Break, continue, and return are
1125  * all handled by setting the evalskip flag.  The evaluation routines
1126  * above all check this flag, and if it is set they start skipping
1127  * commands rather than executing them.  The variable skipcount is
1128  * the number of loops to break/continue, or the number of function
1129  * levels to return.  (The latter is always 1.)  It should probably
1130  * be an error to break out of more loops than exist, but it isn't
1131  * in the standard shell so we don't make it one here.
1132  */
1133
1134 int
1135 breakcmd(int argc, char **argv)
1136 {
1137         int n = argc > 1 ? number(argv[1]) : 1;
1138
1139         if (n > loopnest)
1140                 n = loopnest;
1141         if (n > 0) {
1142                 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1143                 skipcount = n;
1144         }
1145         return 0;
1146 }
1147
1148 /*
1149  * The `command' command.
1150  */
1151 int
1152 commandcmd(int argc, char **argv)
1153 {
1154         const char *path;
1155         int ch;
1156         int cmd = -1;
1157
1158         path = bltinlookup("PATH", 1);
1159
1160         optind = optreset = 1;
1161         opterr = 0;
1162         while ((ch = getopt(argc, argv, "pvV")) != -1) {
1163                 switch (ch) {
1164                 case 'p':
1165                         path = _PATH_STDPATH;
1166                         break;
1167                 case 'v':
1168                         cmd = TYPECMD_SMALLV;
1169                         break;
1170                 case 'V':
1171                         cmd = TYPECMD_BIGV;
1172                         break;
1173                 case '?':
1174                 default:
1175                         error("unknown option: -%c", optopt);
1176                 }
1177         }
1178         argc -= optind;
1179         argv += optind;
1180
1181         if (cmd != -1) {
1182                 if (argc != 1)
1183                         error("wrong number of arguments");
1184                 return typecmd_impl(2, argv - 1, cmd, path);
1185         }
1186         if (argc != 0)
1187                 error("commandcmd bad call");
1188
1189         /*
1190          * Do nothing successfully if no command was specified;
1191          * ksh also does this.
1192          */
1193         return(0);
1194 }
1195
1196
1197 /*
1198  * The return command.
1199  */
1200
1201 int
1202 returncmd(int argc, char **argv)
1203 {
1204         int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1205
1206         if (funcnest) {
1207                 evalskip = SKIPFUNC;
1208                 skipcount = 1;
1209         } else {
1210                 /* skip the rest of the file */
1211                 evalskip = SKIPFILE;
1212                 skipcount = 1;
1213         }
1214         return ret;
1215 }
1216
1217
1218 int
1219 falsecmd(int argc __unused, char **argv __unused)
1220 {
1221         return 1;
1222 }
1223
1224
1225 int
1226 truecmd(int argc __unused, char **argv __unused)
1227 {
1228         return 0;
1229 }
1230
1231
1232 int
1233 execcmd(int argc, char **argv)
1234 {
1235         /*
1236          * Because we have historically not supported any options,
1237          * only treat "--" specially.
1238          */
1239         if (argc > 1 && strcmp(argv[1], "--") == 0)
1240                 argc--, argv++;
1241         if (argc > 1) {
1242                 struct strlist *sp;
1243
1244                 iflag = 0;              /* exit on error */
1245                 mflag = 0;
1246                 optschanged();
1247                 for (sp = cmdenviron; sp ; sp = sp->next)
1248                         setvareq(sp->text, VEXPORT|VSTACK);
1249                 shellexec(argv + 1, environment(), pathval(), 0);
1250
1251         }
1252         return 0;
1253 }
1254
1255
1256 int
1257 timescmd(int argc __unused, char **argv __unused)
1258 {
1259         struct rusage ru;
1260         long shumins, shsmins, chumins, chsmins;
1261         double shusecs, shssecs, chusecs, chssecs;
1262
1263         if (getrusage(RUSAGE_SELF, &ru) < 0)
1264                 return 1;
1265         shumins = ru.ru_utime.tv_sec / 60;
1266         shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1267         shsmins = ru.ru_stime.tv_sec / 60;
1268         shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1269         if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1270                 return 1;
1271         chumins = ru.ru_utime.tv_sec / 60;
1272         chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1273         chsmins = ru.ru_stime.tv_sec / 60;
1274         chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1275         out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1276             shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1277         return 0;
1278 }