eval.c revision 214538 
1/*-
2 * Copyright (c) 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Kenneth Almquist.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#ifndef lint
34#if 0
35static char sccsid[] = "@(#)eval.c	8.9 (Berkeley) 6/8/95";
36#endif
37#endif /* not lint */
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD: head/bin/sh/eval.c 214538 2010-10-29 21:44:43Z jilles $");
40
41#include <paths.h>
42#include <signal.h>
43#include <stdlib.h>
44#include <unistd.h>
45#include <sys/resource.h>
46#include <sys/wait.h> /* For WIFSIGNALED(status) */
47#include <errno.h>
48
49/*
50 * Evaluate a command.
51 */
52
53#include "shell.h"
54#include "nodes.h"
55#include "syntax.h"
56#include "expand.h"
57#include "parser.h"
58#include "jobs.h"
59#include "eval.h"
60#include "builtins.h"
61#include "options.h"
62#include "exec.h"
63#include "redir.h"
64#include "input.h"
65#include "output.h"
66#include "trap.h"
67#include "var.h"
68#include "memalloc.h"
69#include "error.h"
70#include "show.h"
71#include "mystring.h"
72#ifndef NO_HISTORY
73#include "myhistedit.h"
74#endif
75
76
77int evalskip;			/* set if we are skipping commands */
78static int skipcount;		/* number of levels to skip */
79MKINIT int loopnest;		/* current loop nesting level */
80int funcnest;			/* depth of function calls */
81static int builtin_flags;	/* evalcommand flags for builtins */
82
83
84char *commandname;
85struct strlist *cmdenviron;
86int exitstatus;			/* exit status of last command */
87int oexitstatus;		/* saved exit status */
88
89
90static void evalloop(union node *, int);
91static void evalfor(union node *, int);
92static void evalcase(union node *, int);
93static void evalsubshell(union node *, int);
94static void evalredir(union node *, int);
95static void expredir(union node *);
96static void evalpipe(union node *);
97static void evalcommand(union node *, int, struct backcmd *);
98static void prehash(union node *);
99
100
101/*
102 * Called to reset things after an exception.
103 */
104
105#ifdef mkinit
106INCLUDE "eval.h"
107
108RESET {
109	evalskip = 0;
110	loopnest = 0;
111	funcnest = 0;
112}
113
114SHELLPROC {
115	exitstatus = 0;
116}
117#endif
118
119
120
121/*
122 * The eval command.
123 */
124
125int
126evalcmd(int argc, char **argv)
127{
128        char *p;
129        char *concat;
130        char **ap;
131
132        if (argc > 1) {
133                p = argv[1];
134                if (argc > 2) {
135                        STARTSTACKSTR(concat);
136                        ap = argv + 2;
137                        for (;;) {
138                                while (*p)
139                                        STPUTC(*p++, concat);
140                                if ((p = *ap++) == NULL)
141                                        break;
142                                STPUTC(' ', concat);
143                        }
144                        STPUTC('\0', concat);
145                        p = grabstackstr(concat);
146                }
147                evalstring(p, builtin_flags & EV_TESTED);
148        } else
149                exitstatus = 0;
150        return exitstatus;
151}
152
153
154/*
155 * Execute a command or commands contained in a string.
156 */
157
158void
159evalstring(char *s, int flags)
160{
161	union node *n;
162	struct stackmark smark;
163	int flags_exit;
164	int any;
165
166	flags_exit = flags & EV_EXIT;
167	flags &= ~EV_EXIT;
168	any = 0;
169	setstackmark(&smark);
170	setinputstring(s, 1);
171	while ((n = parsecmd(0)) != NEOF) {
172		if (n != NULL) {
173			if (flags_exit && preadateof())
174				evaltree(n, flags | EV_EXIT);
175			else
176				evaltree(n, flags);
177			any = 1;
178		}
179		popstackmark(&smark);
180	}
181	popfile();
182	popstackmark(&smark);
183	if (!any)
184		exitstatus = 0;
185	if (flags_exit)
186		exitshell(exitstatus);
187}
188
189
190/*
191 * Evaluate a parse tree.  The value is left in the global variable
192 * exitstatus.
193 */
194
195void
196evaltree(union node *n, int flags)
197{
198	int do_etest;
199
200	do_etest = 0;
201	if (n == NULL) {
202		TRACE(("evaltree(NULL) called\n"));
203		exitstatus = 0;
204		goto out;
205	}
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		evaltree(n->nbinary.ch2, flags);
216		break;
217	case NAND:
218		evaltree(n->nbinary.ch1, EV_TESTED);
219		if (evalskip || exitstatus != 0) {
220			goto out;
221		}
222		evaltree(n->nbinary.ch2, flags);
223		break;
224	case NOR:
225		evaltree(n->nbinary.ch1, EV_TESTED);
226		if (evalskip || exitstatus == 0)
227			goto out;
228		evaltree(n->nbinary.ch2, flags);
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			evaltree(n->nif.ifpart, flags);
246		else if (n->nif.elsepart)
247			evaltree(n->nif.elsepart, flags);
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, (struct backcmd *)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	}
284out:
285	if (pendingsigs)
286		dotrap();
287	if ((flags & EV_EXIT) || (eflag && exitstatus != 0 && do_etest))
288		exitshell(exitstatus);
289}
290
291
292static void
293evalloop(union node *n, int flags)
294{
295	int status;
296
297	loopnest++;
298	status = 0;
299	for (;;) {
300		evaltree(n->nbinary.ch1, EV_TESTED);
301		if (evalskip) {
302skipping:	  if (evalskip == SKIPCONT && --skipcount <= 0) {
303				evalskip = 0;
304				continue;
305			}
306			if (evalskip == SKIPBREAK && --skipcount <= 0)
307				evalskip = 0;
308			if (evalskip == SKIPFUNC || evalskip == SKIPFILE)
309				status = exitstatus;
310			break;
311		}
312		if (n->type == NWHILE) {
313			if (exitstatus != 0)
314				break;
315		} else {
316			if (exitstatus == 0)
317				break;
318		}
319		evaltree(n->nbinary.ch2, flags);
320		status = exitstatus;
321		if (evalskip)
322			goto skipping;
323	}
324	loopnest--;
325	exitstatus = status;
326}
327
328
329
330static void
331evalfor(union node *n, int flags)
332{
333	struct arglist arglist;
334	union node *argp;
335	struct strlist *sp;
336	struct stackmark smark;
337
338	setstackmark(&smark);
339	arglist.lastp = &arglist.list;
340	for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
341		oexitstatus = exitstatus;
342		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
343		if (evalskip)
344			goto out;
345	}
346	*arglist.lastp = NULL;
347
348	exitstatus = 0;
349	loopnest++;
350	for (sp = arglist.list ; sp ; sp = sp->next) {
351		setvar(n->nfor.var, sp->text, 0);
352		evaltree(n->nfor.body, flags);
353		if (evalskip) {
354			if (evalskip == SKIPCONT && --skipcount <= 0) {
355				evalskip = 0;
356				continue;
357			}
358			if (evalskip == SKIPBREAK && --skipcount <= 0)
359				evalskip = 0;
360			break;
361		}
362	}
363	loopnest--;
364out:
365	popstackmark(&smark);
366}
367
368
369
370static void
371evalcase(union node *n, int flags)
372{
373	union node *cp;
374	union node *patp;
375	struct arglist arglist;
376	struct stackmark smark;
377
378	setstackmark(&smark);
379	arglist.lastp = &arglist.list;
380	oexitstatus = exitstatus;
381	exitstatus = 0;
382	expandarg(n->ncase.expr, &arglist, EXP_TILDE);
383	for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
384		for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
385			if (casematch(patp, arglist.list->text)) {
386				if (evalskip == 0) {
387					evaltree(cp->nclist.body, flags);
388				}
389				goto out;
390			}
391		}
392	}
393out:
394	popstackmark(&smark);
395}
396
397
398
399/*
400 * Kick off a subshell to evaluate a tree.
401 */
402
403static void
404evalsubshell(union node *n, int flags)
405{
406	struct job *jp;
407	int backgnd = (n->type == NBACKGND);
408
409	expredir(n->nredir.redirect);
410	if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
411			forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
412		if (backgnd)
413			flags &=~ EV_TESTED;
414		redirect(n->nredir.redirect, 0);
415		evaltree(n->nredir.n, flags | EV_EXIT);	/* never returns */
416	} else if (! backgnd) {
417		INTOFF;
418		exitstatus = waitforjob(jp, (int *)NULL);
419		INTON;
420	}
421}
422
423
424/*
425 * Evaluate a redirected compound command.
426 */
427
428static void
429evalredir(union node *n, int flags)
430{
431	struct jmploc jmploc;
432	struct jmploc *savehandler;
433	volatile int in_redirect = 1;
434
435	expredir(n->nredir.redirect);
436	savehandler = handler;
437	if (setjmp(jmploc.loc)) {
438		int e;
439
440		handler = savehandler;
441		e = exception;
442		if (e == EXERROR || e == EXEXEC) {
443			popredir();
444			if (in_redirect) {
445				exitstatus = 2;
446				return;
447			}
448		}
449		longjmp(handler->loc, 1);
450	} else {
451		INTOFF;
452		handler = &jmploc;
453		redirect(n->nredir.redirect, REDIR_PUSH);
454		in_redirect = 0;
455		INTON;
456		evaltree(n->nredir.n, flags);
457	}
458	INTOFF;
459	handler = savehandler;
460	popredir();
461	INTON;
462}
463
464
465/*
466 * Compute the names of the files in a redirection list.
467 */
468
469static void
470expredir(union node *n)
471{
472	union node *redir;
473
474	for (redir = n ; redir ; redir = redir->nfile.next) {
475		struct arglist fn;
476		fn.lastp = &fn.list;
477		oexitstatus = exitstatus;
478		switch (redir->type) {
479		case NFROM:
480		case NTO:
481		case NFROMTO:
482		case NAPPEND:
483		case NCLOBBER:
484			expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
485			redir->nfile.expfname = fn.list->text;
486			break;
487		case NFROMFD:
488		case NTOFD:
489			if (redir->ndup.vname) {
490				expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
491				fixredir(redir, fn.list->text, 1);
492			}
493			break;
494		}
495	}
496}
497
498
499
500/*
501 * Evaluate a pipeline.  All the processes in the pipeline are children
502 * of the process creating the pipeline.  (This differs from some versions
503 * of the shell, which make the last process in a pipeline the parent
504 * of all the rest.)
505 */
506
507static void
508evalpipe(union node *n)
509{
510	struct job *jp;
511	struct nodelist *lp;
512	int pipelen;
513	int prevfd;
514	int pip[2];
515
516	TRACE(("evalpipe(%p) called\n", (void *)n));
517	pipelen = 0;
518	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
519		pipelen++;
520	INTOFF;
521	jp = makejob(n, pipelen);
522	prevfd = -1;
523	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
524		prehash(lp->n);
525		pip[1] = -1;
526		if (lp->next) {
527			if (pipe(pip) < 0) {
528				close(prevfd);
529				error("Pipe call failed: %s", strerror(errno));
530			}
531		}
532		if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
533			INTON;
534			if (prevfd > 0) {
535				dup2(prevfd, 0);
536				close(prevfd);
537			}
538			if (pip[1] >= 0) {
539				if (!(prevfd >= 0 && pip[0] == 0))
540					close(pip[0]);
541				if (pip[1] != 1) {
542					dup2(pip[1], 1);
543					close(pip[1]);
544				}
545			}
546			evaltree(lp->n, EV_EXIT);
547		}
548		if (prevfd >= 0)
549			close(prevfd);
550		prevfd = pip[0];
551		close(pip[1]);
552	}
553	INTON;
554	if (n->npipe.backgnd == 0) {
555		INTOFF;
556		exitstatus = waitforjob(jp, (int *)NULL);
557		TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
558		INTON;
559	}
560}
561
562
563
564/*
565 * Execute a command inside back quotes.  If it's a builtin command, we
566 * want to save its output in a block obtained from malloc.  Otherwise
567 * we fork off a subprocess and get the output of the command via a pipe.
568 * Should be called with interrupts off.
569 */
570
571void
572evalbackcmd(union node *n, struct backcmd *result)
573{
574	int pip[2];
575	struct job *jp;
576	struct stackmark smark;		/* unnecessary */
577
578	setstackmark(&smark);
579	result->fd = -1;
580	result->buf = NULL;
581	result->nleft = 0;
582	result->jp = NULL;
583	if (n == NULL) {
584		exitstatus = 0;
585		goto out;
586	}
587	if (n->type == NCMD) {
588		exitstatus = oexitstatus;
589		evalcommand(n, EV_BACKCMD, result);
590	} else {
591		exitstatus = 0;
592		if (pipe(pip) < 0)
593			error("Pipe call failed: %s", strerror(errno));
594		jp = makejob(n, 1);
595		if (forkshell(jp, n, FORK_NOJOB) == 0) {
596			FORCEINTON;
597			close(pip[0]);
598			if (pip[1] != 1) {
599				dup2(pip[1], 1);
600				close(pip[1]);
601			}
602			evaltree(n, EV_EXIT);
603		}
604		close(pip[1]);
605		result->fd = pip[0];
606		result->jp = jp;
607	}
608out:
609	popstackmark(&smark);
610	TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
611		result->fd, result->buf, result->nleft, result->jp));
612}
613
614
615
616/*
617 * Execute a simple command.
618 */
619
620static void
621evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
622{
623	struct stackmark smark;
624	union node *argp;
625	struct arglist arglist;
626	struct arglist varlist;
627	char **argv;
628	int argc;
629	char **envp;
630	int varflag;
631	struct strlist *sp;
632	int mode;
633	int pip[2];
634	struct cmdentry cmdentry;
635	struct job *jp;
636	struct jmploc jmploc;
637	struct jmploc *savehandler;
638	char *savecmdname;
639	struct shparam saveparam;
640	struct localvar *savelocalvars;
641	struct parsefile *savetopfile;
642	volatile int e;
643	char *lastarg;
644	int realstatus;
645	int do_clearcmdentry;
646	const char *path = pathval();
647
648	/* First expand the arguments. */
649	TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
650	setstackmark(&smark);
651	arglist.lastp = &arglist.list;
652	varlist.lastp = &varlist.list;
653	varflag = 1;
654	do_clearcmdentry = 0;
655	oexitstatus = exitstatus;
656	exitstatus = 0;
657	for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
658		char *p = argp->narg.text;
659		if (varflag && is_name(*p)) {
660			do {
661				p++;
662			} while (is_in_name(*p));
663			if (*p == '=') {
664				expandarg(argp, &varlist, EXP_VARTILDE);
665				continue;
666			}
667		}
668		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
669		varflag = 0;
670	}
671	*arglist.lastp = NULL;
672	*varlist.lastp = NULL;
673	expredir(cmd->ncmd.redirect);
674	argc = 0;
675	for (sp = arglist.list ; sp ; sp = sp->next)
676		argc++;
677	argv = stalloc(sizeof (char *) * (argc + 1));
678
679	for (sp = arglist.list ; sp ; sp = sp->next) {
680		TRACE(("evalcommand arg: %s\n", sp->text));
681		*argv++ = sp->text;
682	}
683	*argv = NULL;
684	lastarg = NULL;
685	if (iflag && funcnest == 0 && argc > 0)
686		lastarg = argv[-1];
687	argv -= argc;
688
689	/* Print the command if xflag is set. */
690	if (xflag) {
691		char sep = 0;
692		const char *p;
693		out2str(ps4val());
694		for (sp = varlist.list ; sp ; sp = sp->next) {
695			if (sep != 0)
696				out2c(' ');
697			p = sp->text;
698			while (*p != '=' && *p != '\0')
699				out2c(*p++);
700			if (*p != '\0') {
701				out2c(*p++);
702				out2qstr(p);
703			}
704			sep = ' ';
705		}
706		for (sp = arglist.list ; sp ; sp = sp->next) {
707			if (sep != 0)
708				out2c(' ');
709			/* Disambiguate command looking like assignment. */
710			if (sp == arglist.list &&
711					strchr(sp->text, '=') != NULL &&
712					strchr(sp->text, '\'') == NULL) {
713				out2c('\'');
714				out2str(sp->text);
715				out2c('\'');
716			} else
717				out2qstr(sp->text);
718			sep = ' ';
719		}
720		out2c('\n');
721		flushout(&errout);
722	}
723
724	/* Now locate the command. */
725	if (argc == 0) {
726		/* Variable assignment(s) without command */
727		cmdentry.cmdtype = CMDBUILTIN;
728		cmdentry.u.index = BLTINCMD;
729		cmdentry.special = 0;
730	} else {
731		static const char PATH[] = "PATH=";
732		int cmd_flags = 0, bltinonly = 0;
733
734		/*
735		 * Modify the command lookup path, if a PATH= assignment
736		 * is present
737		 */
738		for (sp = varlist.list ; sp ; sp = sp->next)
739			if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
740				path = sp->text + sizeof(PATH) - 1;
741				/*
742				 * On `PATH=... command`, we need to make
743				 * sure that the command isn't using the
744				 * non-updated hash table of the outer PATH
745				 * setting and we need to make sure that
746				 * the hash table isn't filled with items
747				 * from the temporary setting.
748				 *
749				 * It would be better to forbit using and
750				 * updating the table while this command
751				 * runs, by the command finding mechanism
752				 * is heavily integrated with hash handling,
753				 * so we just delete the hash before and after
754				 * the command runs. Partly deleting like
755				 * changepatch() does doesn't seem worth the
756				 * bookinging effort, since most such runs add
757				 * directories in front of the new PATH.
758				 */
759				clearcmdentry(0);
760				do_clearcmdentry = 1;
761			}
762
763		for (;;) {
764			if (bltinonly) {
765				cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
766				if (cmdentry.u.index < 0) {
767					cmdentry.u.index = BLTINCMD;
768					argv--;
769					argc++;
770					break;
771				}
772			} else
773				find_command(argv[0], &cmdentry, cmd_flags, path);
774			/* implement the bltin and command builtins here */
775			if (cmdentry.cmdtype != CMDBUILTIN)
776				break;
777			if (cmdentry.u.index == BLTINCMD) {
778				if (argc == 1)
779					break;
780				argv++;
781				argc--;
782				bltinonly = 1;
783			} else if (cmdentry.u.index == COMMANDCMD) {
784				if (argc == 1)
785					break;
786				if (!strcmp(argv[1], "-p")) {
787					if (argc == 2)
788						break;
789					if (argv[2][0] == '-') {
790						if (strcmp(argv[2], "--"))
791							break;
792						if (argc == 3)
793							break;
794						argv += 3;
795						argc -= 3;
796					} else {
797						argv += 2;
798						argc -= 2;
799					}
800					path = _PATH_STDPATH;
801					clearcmdentry(0);
802					do_clearcmdentry = 1;
803				} else if (!strcmp(argv[1], "--")) {
804					if (argc == 2)
805						break;
806					argv += 2;
807					argc -= 2;
808				} else if (argv[1][0] == '-')
809					break;
810				else {
811					argv++;
812					argc--;
813				}
814				cmd_flags |= DO_NOFUNC;
815				bltinonly = 0;
816			} else
817				break;
818		}
819		/*
820		 * Special builtins lose their special properties when
821		 * called via 'command'.
822		 */
823		if (cmd_flags & DO_NOFUNC)
824			cmdentry.special = 0;
825	}
826
827	/* Fork off a child process if necessary. */
828	if (cmd->ncmd.backgnd
829	 || ((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
830	    && ((flags & EV_EXIT) == 0 || have_traps()))
831	 || ((flags & EV_BACKCMD) != 0
832	    && (cmdentry.cmdtype != CMDBUILTIN
833		 || cmdentry.u.index == CDCMD
834		 || cmdentry.u.index == DOTCMD
835		 || cmdentry.u.index == EVALCMD))) {
836		jp = makejob(cmd, 1);
837		mode = cmd->ncmd.backgnd;
838		if (flags & EV_BACKCMD) {
839			mode = FORK_NOJOB;
840			if (pipe(pip) < 0)
841				error("Pipe call failed: %s", strerror(errno));
842		}
843		if (forkshell(jp, cmd, mode) != 0)
844			goto parent;	/* at end of routine */
845		if (flags & EV_BACKCMD) {
846			FORCEINTON;
847			close(pip[0]);
848			if (pip[1] != 1) {
849				dup2(pip[1], 1);
850				close(pip[1]);
851			}
852		}
853		flags |= EV_EXIT;
854	}
855
856	/* This is the child process if a fork occurred. */
857	/* Execute the command. */
858	if (cmdentry.cmdtype == CMDFUNCTION) {
859#ifdef DEBUG
860		trputs("Shell function:  ");  trargs(argv);
861#endif
862		saveparam = shellparam;
863		shellparam.malloc = 0;
864		shellparam.reset = 1;
865		shellparam.nparam = argc - 1;
866		shellparam.p = argv + 1;
867		shellparam.optnext = NULL;
868		INTOFF;
869		savelocalvars = localvars;
870		localvars = NULL;
871		reffunc(cmdentry.u.func);
872		savehandler = handler;
873		if (setjmp(jmploc.loc)) {
874			if (exception == EXSHELLPROC)
875				freeparam(&saveparam);
876			else {
877				freeparam(&shellparam);
878				shellparam = saveparam;
879				if (exception == EXERROR || exception == EXEXEC)
880					popredir();
881			}
882			unreffunc(cmdentry.u.func);
883			poplocalvars();
884			localvars = savelocalvars;
885			funcnest--;
886			handler = savehandler;
887			longjmp(handler->loc, 1);
888		}
889		handler = &jmploc;
890		funcnest++;
891		redirect(cmd->ncmd.redirect, REDIR_PUSH);
892		INTON;
893		for (sp = varlist.list ; sp ; sp = sp->next)
894			mklocal(sp->text);
895		exitstatus = oexitstatus;
896		if (flags & EV_TESTED)
897			evaltree(getfuncnode(cmdentry.u.func), EV_TESTED);
898		else
899			evaltree(getfuncnode(cmdentry.u.func), 0);
900		INTOFF;
901		unreffunc(cmdentry.u.func);
902		poplocalvars();
903		localvars = savelocalvars;
904		freeparam(&shellparam);
905		shellparam = saveparam;
906		handler = savehandler;
907		funcnest--;
908		popredir();
909		INTON;
910		if (evalskip == SKIPFUNC) {
911			evalskip = 0;
912			skipcount = 0;
913		}
914		if (flags & EV_EXIT)
915			exitshell(exitstatus);
916	} else if (cmdentry.cmdtype == CMDBUILTIN) {
917#ifdef DEBUG
918		trputs("builtin command:  ");  trargs(argv);
919#endif
920		mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
921		if (flags == EV_BACKCMD) {
922			memout.nleft = 0;
923			memout.nextc = memout.buf;
924			memout.bufsize = 64;
925			mode |= REDIR_BACKQ;
926			cmdentry.special = 0;
927		}
928		savecmdname = commandname;
929		savetopfile = getcurrentfile();
930		cmdenviron = varlist.list;
931		e = -1;
932		savehandler = handler;
933		if (setjmp(jmploc.loc)) {
934			e = exception;
935			exitstatus = (e == EXINT)? SIGINT+128 : 2;
936			goto cmddone;
937		}
938		handler = &jmploc;
939		redirect(cmd->ncmd.redirect, mode);
940		/*
941		 * If there is no command word, redirection errors should
942		 * not be fatal but assignment errors should.
943		 */
944		if (argc == 0 && !(flags & EV_BACKCMD))
945			cmdentry.special = 1;
946		if (cmdentry.special)
947			listsetvar(cmdenviron);
948		if (argc > 0)
949			bltinsetlocale();
950		commandname = argv[0];
951		argptr = argv + 1;
952		nextopt_optptr = NULL;		/* initialize nextopt */
953		builtin_flags = flags;
954		exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
955		flushall();
956cmddone:
957		if (argc > 0)
958			bltinunsetlocale();
959		cmdenviron = NULL;
960		out1 = &output;
961		out2 = &errout;
962		freestdout();
963		if (e != EXSHELLPROC) {
964			commandname = savecmdname;
965			if (flags & EV_EXIT) {
966				exitshell(exitstatus);
967			}
968		}
969		handler = savehandler;
970		if (flags == EV_BACKCMD) {
971			backcmd->buf = memout.buf;
972			backcmd->nleft = memout.nextc - memout.buf;
973			memout.buf = NULL;
974		}
975		if (cmdentry.u.index != EXECCMD &&
976				(e == -1 || e == EXERROR || e == EXEXEC))
977			popredir();
978		if (e != -1) {
979			if ((e != EXERROR && e != EXEXEC)
980			    || cmdentry.special)
981				exraise(e);
982			popfilesupto(savetopfile);
983			if (flags != EV_BACKCMD)
984				FORCEINTON;
985		}
986	} else {
987#ifdef DEBUG
988		trputs("normal command:  ");  trargs(argv);
989#endif
990		redirect(cmd->ncmd.redirect, 0);
991		for (sp = varlist.list ; sp ; sp = sp->next)
992			setvareq(sp->text, VEXPORT|VSTACK);
993		envp = environment();
994		shellexec(argv, envp, path, cmdentry.u.index);
995		/*NOTREACHED*/
996	}
997	goto out;
998
999parent:	/* parent process gets here (if we forked) */
1000	if (mode == FORK_FG) {	/* argument to fork */
1001		INTOFF;
1002		exitstatus = waitforjob(jp, &realstatus);
1003		INTON;
1004		if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1005			evalskip = SKIPBREAK;
1006			skipcount = loopnest;
1007		}
1008	} else if (mode == FORK_NOJOB) {
1009		backcmd->fd = pip[0];
1010		close(pip[1]);
1011		backcmd->jp = jp;
1012	}
1013
1014out:
1015	if (lastarg)
1016		setvar("_", lastarg, 0);
1017	if (do_clearcmdentry)
1018		clearcmdentry(0);
1019	popstackmark(&smark);
1020}
1021
1022
1023
1024/*
1025 * Search for a command.  This is called before we fork so that the
1026 * location of the command will be available in the parent as well as
1027 * the child.  The check for "goodname" is an overly conservative
1028 * check that the name will not be subject to expansion.
1029 */
1030
1031static void
1032prehash(union node *n)
1033{
1034	struct cmdentry entry;
1035
1036	if (n && n->type == NCMD && n->ncmd.args)
1037		if (goodname(n->ncmd.args->narg.text))
1038			find_command(n->ncmd.args->narg.text, &entry, 0,
1039				     pathval());
1040}
1041
1042
1043
1044/*
1045 * Builtin commands.  Builtin commands whose functions are closely
1046 * tied to evaluation are implemented here.
1047 */
1048
1049/*
1050 * No command given, a bltin command with no arguments, or a bltin command
1051 * with an invalid name.
1052 */
1053
1054int
1055bltincmd(int argc, char **argv)
1056{
1057	if (argc > 1) {
1058		out2fmt_flush("%s: not found\n", argv[1]);
1059		return 127;
1060	}
1061	/*
1062	 * Preserve exitstatus of a previous possible redirection
1063	 * as POSIX mandates
1064	 */
1065	return exitstatus;
1066}
1067
1068
1069/*
1070 * Handle break and continue commands.  Break, continue, and return are
1071 * all handled by setting the evalskip flag.  The evaluation routines
1072 * above all check this flag, and if it is set they start skipping
1073 * commands rather than executing them.  The variable skipcount is
1074 * the number of loops to break/continue, or the number of function
1075 * levels to return.  (The latter is always 1.)  It should probably
1076 * be an error to break out of more loops than exist, but it isn't
1077 * in the standard shell so we don't make it one here.
1078 */
1079
1080int
1081breakcmd(int argc, char **argv)
1082{
1083	int n = argc > 1 ? number(argv[1]) : 1;
1084
1085	if (n > loopnest)
1086		n = loopnest;
1087	if (n > 0) {
1088		evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1089		skipcount = n;
1090	}
1091	return 0;
1092}
1093
1094/*
1095 * The `command' command.
1096 */
1097int
1098commandcmd(int argc, char **argv)
1099{
1100	const char *path;
1101	int ch;
1102	int cmd = -1;
1103
1104	path = bltinlookup("PATH", 1);
1105
1106	optind = optreset = 1;
1107	opterr = 0;
1108	while ((ch = getopt(argc, argv, "pvV")) != -1) {
1109		switch (ch) {
1110		case 'p':
1111			path = _PATH_STDPATH;
1112			break;
1113		case 'v':
1114			cmd = TYPECMD_SMALLV;
1115			break;
1116		case 'V':
1117			cmd = TYPECMD_BIGV;
1118			break;
1119		case '?':
1120		default:
1121			error("unknown option: -%c", optopt);
1122		}
1123	}
1124	argc -= optind;
1125	argv += optind;
1126
1127	if (cmd != -1) {
1128		if (argc != 1)
1129			error("wrong number of arguments");
1130		return typecmd_impl(2, argv - 1, cmd, path);
1131	}
1132	if (argc != 0)
1133		error("commandcmd bad call");
1134
1135	/*
1136	 * Do nothing successfully if no command was specified;
1137	 * ksh also does this.
1138	 */
1139	return 0;
1140}
1141
1142
1143/*
1144 * The return command.
1145 */
1146
1147int
1148returncmd(int argc, char **argv)
1149{
1150	int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1151
1152	if (funcnest) {
1153		evalskip = SKIPFUNC;
1154		skipcount = 1;
1155	} else {
1156		/* skip the rest of the file */
1157		evalskip = SKIPFILE;
1158		skipcount = 1;
1159	}
1160	return ret;
1161}
1162
1163
1164int
1165falsecmd(int argc __unused, char **argv __unused)
1166{
1167	return 1;
1168}
1169
1170
1171int
1172truecmd(int argc __unused, char **argv __unused)
1173{
1174	return 0;
1175}
1176
1177
1178int
1179execcmd(int argc, char **argv)
1180{
1181	/*
1182	 * Because we have historically not supported any options,
1183	 * only treat "--" specially.
1184	 */
1185	if (argc > 1 && strcmp(argv[1], "--") == 0)
1186		argc--, argv++;
1187	if (argc > 1) {
1188		struct strlist *sp;
1189
1190		iflag = 0;		/* exit on error */
1191		mflag = 0;
1192		optschanged();
1193		for (sp = cmdenviron; sp ; sp = sp->next)
1194			setvareq(sp->text, VEXPORT|VSTACK);
1195		shellexec(argv + 1, environment(), pathval(), 0);
1196
1197	}
1198	return 0;
1199}
1200
1201
1202int
1203timescmd(int argc __unused, char **argv __unused)
1204{
1205	struct rusage ru;
1206	long shumins, shsmins, chumins, chsmins;
1207	double shusecs, shssecs, chusecs, chssecs;
1208
1209	if (getrusage(RUSAGE_SELF, &ru) < 0)
1210		return 1;
1211	shumins = ru.ru_utime.tv_sec / 60;
1212	shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1213	shsmins = ru.ru_stime.tv_sec / 60;
1214	shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1215	if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1216		return 1;
1217	chumins = ru.ru_utime.tv_sec / 60;
1218	chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1219	chsmins = ru.ru_stime.tv_sec / 60;
1220	chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1221	out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1222	    shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1223	return 0;
1224}
1225