eval.c revision 210829 
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 210829 2010-08-03 22:17:29Z 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			break;
309		}
310		if (n->type == NWHILE) {
311			if (exitstatus != 0)
312				break;
313		} else {
314			if (exitstatus == 0)
315				break;
316		}
317		evaltree(n->nbinary.ch2, flags);
318		status = exitstatus;
319		if (evalskip)
320			goto skipping;
321	}
322	loopnest--;
323	exitstatus = status;
324}
325
326
327
328STATIC void
329evalfor(union node *n, int flags)
330{
331	struct arglist arglist;
332	union node *argp;
333	struct strlist *sp;
334	struct stackmark smark;
335
336	setstackmark(&smark);
337	arglist.lastp = &arglist.list;
338	for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
339		oexitstatus = exitstatus;
340		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
341		if (evalskip)
342			goto out;
343	}
344	*arglist.lastp = NULL;
345
346	exitstatus = 0;
347	loopnest++;
348	for (sp = arglist.list ; sp ; sp = sp->next) {
349		setvar(n->nfor.var, sp->text, 0);
350		evaltree(n->nfor.body, flags);
351		if (evalskip) {
352			if (evalskip == SKIPCONT && --skipcount <= 0) {
353				evalskip = 0;
354				continue;
355			}
356			if (evalskip == SKIPBREAK && --skipcount <= 0)
357				evalskip = 0;
358			break;
359		}
360	}
361	loopnest--;
362out:
363	popstackmark(&smark);
364}
365
366
367
368STATIC void
369evalcase(union node *n, int flags)
370{
371	union node *cp;
372	union node *patp;
373	struct arglist arglist;
374	struct stackmark smark;
375
376	setstackmark(&smark);
377	arglist.lastp = &arglist.list;
378	oexitstatus = exitstatus;
379	exitstatus = 0;
380	expandarg(n->ncase.expr, &arglist, EXP_TILDE);
381	for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
382		for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
383			if (casematch(patp, arglist.list->text)) {
384				if (evalskip == 0) {
385					evaltree(cp->nclist.body, flags);
386				}
387				goto out;
388			}
389		}
390	}
391out:
392	popstackmark(&smark);
393}
394
395
396
397/*
398 * Kick off a subshell to evaluate a tree.
399 */
400
401STATIC void
402evalsubshell(union node *n, int flags)
403{
404	struct job *jp;
405	int backgnd = (n->type == NBACKGND);
406
407	expredir(n->nredir.redirect);
408	if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
409			forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
410		if (backgnd)
411			flags &=~ EV_TESTED;
412		redirect(n->nredir.redirect, 0);
413		evaltree(n->nredir.n, flags | EV_EXIT);	/* never returns */
414	} else if (! backgnd) {
415		INTOFF;
416		exitstatus = waitforjob(jp, (int *)NULL);
417		INTON;
418	}
419}
420
421
422/*
423 * Evaluate a redirected compound command.
424 */
425
426STATIC void
427evalredir(union node *n, int flags)
428{
429	struct jmploc jmploc;
430	struct jmploc *savehandler;
431	volatile int in_redirect = 1;
432
433	expredir(n->nredir.redirect);
434	savehandler = handler;
435	if (setjmp(jmploc.loc)) {
436		int e;
437
438		handler = savehandler;
439		e = exception;
440		if (e == EXERROR || e == EXEXEC) {
441			popredir();
442			if (in_redirect) {
443				exitstatus = 2;
444				return;
445			}
446		}
447		longjmp(handler->loc, 1);
448	} else {
449		INTOFF;
450		handler = &jmploc;
451		redirect(n->nredir.redirect, REDIR_PUSH);
452		in_redirect = 0;
453		INTON;
454		evaltree(n->nredir.n, flags);
455	}
456	INTOFF;
457	handler = savehandler;
458	popredir();
459	INTON;
460}
461
462
463/*
464 * Compute the names of the files in a redirection list.
465 */
466
467STATIC void
468expredir(union node *n)
469{
470	union node *redir;
471
472	for (redir = n ; redir ; redir = redir->nfile.next) {
473		struct arglist fn;
474		fn.lastp = &fn.list;
475		oexitstatus = exitstatus;
476		switch (redir->type) {
477		case NFROM:
478		case NTO:
479		case NFROMTO:
480		case NAPPEND:
481		case NCLOBBER:
482			expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
483			redir->nfile.expfname = fn.list->text;
484			break;
485		case NFROMFD:
486		case NTOFD:
487			if (redir->ndup.vname) {
488				expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
489				fixredir(redir, fn.list->text, 1);
490			}
491			break;
492		}
493	}
494}
495
496
497
498/*
499 * Evaluate a pipeline.  All the processes in the pipeline are children
500 * of the process creating the pipeline.  (This differs from some versions
501 * of the shell, which make the last process in a pipeline the parent
502 * of all the rest.)
503 */
504
505STATIC void
506evalpipe(union node *n)
507{
508	struct job *jp;
509	struct nodelist *lp;
510	int pipelen;
511	int prevfd;
512	int pip[2];
513
514	TRACE(("evalpipe(%p) called\n", (void *)n));
515	pipelen = 0;
516	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
517		pipelen++;
518	INTOFF;
519	jp = makejob(n, pipelen);
520	prevfd = -1;
521	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
522		prehash(lp->n);
523		pip[1] = -1;
524		if (lp->next) {
525			if (pipe(pip) < 0) {
526				close(prevfd);
527				error("Pipe call failed: %s", strerror(errno));
528			}
529		}
530		if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
531			INTON;
532			if (prevfd > 0) {
533				dup2(prevfd, 0);
534				close(prevfd);
535			}
536			if (pip[1] >= 0) {
537				if (!(prevfd >= 0 && pip[0] == 0))
538					close(pip[0]);
539				if (pip[1] != 1) {
540					dup2(pip[1], 1);
541					close(pip[1]);
542				}
543			}
544			evaltree(lp->n, EV_EXIT);
545		}
546		if (prevfd >= 0)
547			close(prevfd);
548		prevfd = pip[0];
549		close(pip[1]);
550	}
551	INTON;
552	if (n->npipe.backgnd == 0) {
553		INTOFF;
554		exitstatus = waitforjob(jp, (int *)NULL);
555		TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
556		INTON;
557	}
558}
559
560
561
562/*
563 * Execute a command inside back quotes.  If it's a builtin command, we
564 * want to save its output in a block obtained from malloc.  Otherwise
565 * we fork off a subprocess and get the output of the command via a pipe.
566 * Should be called with interrupts off.
567 */
568
569void
570evalbackcmd(union node *n, struct backcmd *result)
571{
572	int pip[2];
573	struct job *jp;
574	struct stackmark smark;		/* unnecessary */
575
576	setstackmark(&smark);
577	result->fd = -1;
578	result->buf = NULL;
579	result->nleft = 0;
580	result->jp = NULL;
581	if (n == NULL) {
582		exitstatus = 0;
583		goto out;
584	}
585	if (n->type == NCMD) {
586		exitstatus = oexitstatus;
587		evalcommand(n, EV_BACKCMD, result);
588	} else {
589		exitstatus = 0;
590		if (pipe(pip) < 0)
591			error("Pipe call failed: %s", strerror(errno));
592		jp = makejob(n, 1);
593		if (forkshell(jp, n, FORK_NOJOB) == 0) {
594			FORCEINTON;
595			close(pip[0]);
596			if (pip[1] != 1) {
597				dup2(pip[1], 1);
598				close(pip[1]);
599			}
600			evaltree(n, EV_EXIT);
601		}
602		close(pip[1]);
603		result->fd = pip[0];
604		result->jp = jp;
605	}
606out:
607	popstackmark(&smark);
608	TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
609		result->fd, result->buf, result->nleft, result->jp));
610}
611
612
613
614/*
615 * Execute a simple command.
616 */
617
618STATIC void
619evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
620{
621	struct stackmark smark;
622	union node *argp;
623	struct arglist arglist;
624	struct arglist varlist;
625	char **argv;
626	int argc;
627	char **envp;
628	int varflag;
629	struct strlist *sp;
630	int mode;
631	int pip[2];
632	struct cmdentry cmdentry;
633	struct job *jp;
634	struct jmploc jmploc;
635	struct jmploc *savehandler;
636	char *savecmdname;
637	struct shparam saveparam;
638	struct localvar *savelocalvars;
639	struct parsefile *savetopfile;
640	volatile int e;
641	char *lastarg;
642	int realstatus;
643	int do_clearcmdentry;
644	char *path = pathval();
645
646	/* First expand the arguments. */
647	TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
648	setstackmark(&smark);
649	arglist.lastp = &arglist.list;
650	varlist.lastp = &varlist.list;
651	varflag = 1;
652	do_clearcmdentry = 0;
653	oexitstatus = exitstatus;
654	exitstatus = 0;
655	for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
656		char *p = argp->narg.text;
657		if (varflag && is_name(*p)) {
658			do {
659				p++;
660			} while (is_in_name(*p));
661			if (*p == '=') {
662				expandarg(argp, &varlist, EXP_VARTILDE);
663				continue;
664			}
665		}
666		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
667		varflag = 0;
668	}
669	*arglist.lastp = NULL;
670	*varlist.lastp = NULL;
671	expredir(cmd->ncmd.redirect);
672	argc = 0;
673	for (sp = arglist.list ; sp ; sp = sp->next)
674		argc++;
675	argv = stalloc(sizeof (char *) * (argc + 1));
676
677	for (sp = arglist.list ; sp ; sp = sp->next) {
678		TRACE(("evalcommand arg: %s\n", sp->text));
679		*argv++ = sp->text;
680	}
681	*argv = NULL;
682	lastarg = NULL;
683	if (iflag && funcnest == 0 && argc > 0)
684		lastarg = argv[-1];
685	argv -= argc;
686
687	/* Print the command if xflag is set. */
688	if (xflag) {
689		char sep = 0;
690		const char *p;
691		out2str(ps4val());
692		for (sp = varlist.list ; sp ; sp = sp->next) {
693			if (sep != 0)
694				out2c(' ');
695			p = sp->text;
696			while (*p != '=' && *p != '\0')
697				out2c(*p++);
698			if (*p != '\0') {
699				out2c(*p++);
700				out2qstr(p);
701			}
702			sep = ' ';
703		}
704		for (sp = arglist.list ; sp ; sp = sp->next) {
705			if (sep != 0)
706				out2c(' ');
707			/* Disambiguate command looking like assignment. */
708			if (sp == arglist.list &&
709					strchr(sp->text, '=') != NULL &&
710					strchr(sp->text, '\'') == NULL) {
711				out2c('\'');
712				out2str(sp->text);
713				out2c('\'');
714			} else
715				out2qstr(sp->text);
716			sep = ' ';
717		}
718		out2c('\n');
719		flushout(&errout);
720	}
721
722	/* Now locate the command. */
723	if (argc == 0) {
724		/* Variable assignment(s) without command */
725		cmdentry.cmdtype = CMDBUILTIN;
726		cmdentry.u.index = BLTINCMD;
727		cmdentry.special = 0;
728	} else {
729		static const char PATH[] = "PATH=";
730		int cmd_flags = 0, bltinonly = 0;
731
732		/*
733		 * Modify the command lookup path, if a PATH= assignment
734		 * is present
735		 */
736		for (sp = varlist.list ; sp ; sp = sp->next)
737			if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
738				path = sp->text + sizeof(PATH) - 1;
739				/*
740				 * On `PATH=... command`, we need to make
741				 * sure that the command isn't using the
742				 * non-updated hash table of the outer PATH
743				 * setting and we need to make sure that
744				 * the hash table isn't filled with items
745				 * from the temporary setting.
746				 *
747				 * It would be better to forbit using and
748				 * updating the table while this command
749				 * runs, by the command finding mechanism
750				 * is heavily integrated with hash handling,
751				 * so we just delete the hash before and after
752				 * the command runs. Partly deleting like
753				 * changepatch() does doesn't seem worth the
754				 * bookinging effort, since most such runs add
755				 * directories in front of the new PATH.
756				 */
757				clearcmdentry(0);
758				do_clearcmdentry = 1;
759			}
760
761		for (;;) {
762			if (bltinonly) {
763				cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
764				if (cmdentry.u.index < 0) {
765					cmdentry.u.index = BLTINCMD;
766					argv--;
767					argc++;
768					break;
769				}
770			} else
771				find_command(argv[0], &cmdentry, cmd_flags, path);
772			/* implement the bltin and command builtins here */
773			if (cmdentry.cmdtype != CMDBUILTIN)
774				break;
775			if (cmdentry.u.index == BLTINCMD) {
776				if (argc == 1)
777					break;
778				argv++;
779				argc--;
780				bltinonly = 1;
781			} else if (cmdentry.u.index == COMMANDCMD) {
782				if (argc == 1)
783					break;
784				if (!strcmp(argv[1], "-p")) {
785					if (argc == 2)
786						break;
787					if (argv[2][0] == '-') {
788						if (strcmp(argv[2], "--"))
789							break;
790						if (argc == 3)
791							break;
792						argv += 3;
793						argc -= 3;
794					} else {
795						argv += 2;
796						argc -= 2;
797					}
798					path = _PATH_STDPATH;
799					clearcmdentry(0);
800					do_clearcmdentry = 1;
801				} else if (!strcmp(argv[1], "--")) {
802					if (argc == 2)
803						break;
804					argv += 2;
805					argc -= 2;
806				} else if (argv[1][0] == '-')
807					break;
808				else {
809					argv++;
810					argc--;
811				}
812				cmd_flags |= DO_NOFUNC;
813				bltinonly = 0;
814			} else
815				break;
816		}
817		/*
818		 * Special builtins lose their special properties when
819		 * called via 'command'.
820		 */
821		if (cmd_flags & DO_NOFUNC)
822			cmdentry.special = 0;
823	}
824
825	/* Fork off a child process if necessary. */
826	if (cmd->ncmd.backgnd
827	 || ((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
828	    && ((flags & EV_EXIT) == 0 || have_traps()))
829	 || ((flags & EV_BACKCMD) != 0
830	    && (cmdentry.cmdtype != CMDBUILTIN
831		 || cmdentry.u.index == CDCMD
832		 || cmdentry.u.index == DOTCMD
833		 || cmdentry.u.index == EVALCMD))) {
834		jp = makejob(cmd, 1);
835		mode = cmd->ncmd.backgnd;
836		if (flags & EV_BACKCMD) {
837			mode = FORK_NOJOB;
838			if (pipe(pip) < 0)
839				error("Pipe call failed: %s", strerror(errno));
840		}
841		if (forkshell(jp, cmd, mode) != 0)
842			goto parent;	/* at end of routine */
843		if (flags & EV_BACKCMD) {
844			FORCEINTON;
845			close(pip[0]);
846			if (pip[1] != 1) {
847				dup2(pip[1], 1);
848				close(pip[1]);
849			}
850		}
851		flags |= EV_EXIT;
852	}
853
854	/* This is the child process if a fork occurred. */
855	/* Execute the command. */
856	if (cmdentry.cmdtype == CMDFUNCTION) {
857#ifdef DEBUG
858		trputs("Shell function:  ");  trargs(argv);
859#endif
860		saveparam = shellparam;
861		shellparam.malloc = 0;
862		shellparam.reset = 1;
863		shellparam.nparam = argc - 1;
864		shellparam.p = argv + 1;
865		shellparam.optnext = NULL;
866		INTOFF;
867		savelocalvars = localvars;
868		localvars = NULL;
869		reffunc(cmdentry.u.func);
870		savehandler = handler;
871		if (setjmp(jmploc.loc)) {
872			if (exception == EXSHELLPROC)
873				freeparam(&saveparam);
874			else {
875				freeparam(&shellparam);
876				shellparam = saveparam;
877				if (exception == EXERROR || exception == EXEXEC)
878					popredir();
879			}
880			unreffunc(cmdentry.u.func);
881			poplocalvars();
882			localvars = savelocalvars;
883			funcnest--;
884			handler = savehandler;
885			longjmp(handler->loc, 1);
886		}
887		handler = &jmploc;
888		funcnest++;
889		redirect(cmd->ncmd.redirect, REDIR_PUSH);
890		INTON;
891		for (sp = varlist.list ; sp ; sp = sp->next)
892			mklocal(sp->text);
893		exitstatus = oexitstatus;
894		if (flags & EV_TESTED)
895			evaltree(getfuncnode(cmdentry.u.func), EV_TESTED);
896		else
897			evaltree(getfuncnode(cmdentry.u.func), 0);
898		INTOFF;
899		unreffunc(cmdentry.u.func);
900		poplocalvars();
901		localvars = savelocalvars;
902		freeparam(&shellparam);
903		shellparam = saveparam;
904		handler = savehandler;
905		funcnest--;
906		popredir();
907		INTON;
908		if (evalskip == SKIPFUNC) {
909			evalskip = 0;
910			skipcount = 0;
911		}
912		if (flags & EV_EXIT)
913			exitshell(exitstatus);
914	} else if (cmdentry.cmdtype == CMDBUILTIN) {
915#ifdef DEBUG
916		trputs("builtin command:  ");  trargs(argv);
917#endif
918		mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
919		if (flags == EV_BACKCMD) {
920			memout.nleft = 0;
921			memout.nextc = memout.buf;
922			memout.bufsize = 64;
923			mode |= REDIR_BACKQ;
924			cmdentry.special = 0;
925		}
926		savecmdname = commandname;
927		savetopfile = getcurrentfile();
928		cmdenviron = varlist.list;
929		e = -1;
930		savehandler = handler;
931		if (setjmp(jmploc.loc)) {
932			e = exception;
933			exitstatus = (e == EXINT)? SIGINT+128 : 2;
934			goto cmddone;
935		}
936		handler = &jmploc;
937		redirect(cmd->ncmd.redirect, mode);
938		/*
939		 * If there is no command word, redirection errors should
940		 * not be fatal but assignment errors should.
941		 */
942		if (argc == 0 && !(flags & EV_BACKCMD))
943			cmdentry.special = 1;
944		if (cmdentry.special)
945			listsetvar(cmdenviron);
946		if (argc > 0)
947			bltinsetlocale();
948		commandname = argv[0];
949		argptr = argv + 1;
950		nextopt_optptr = NULL;		/* initialize nextopt */
951		builtin_flags = flags;
952		exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
953		flushall();
954cmddone:
955		if (argc > 0)
956			bltinunsetlocale();
957		cmdenviron = NULL;
958		out1 = &output;
959		out2 = &errout;
960		freestdout();
961		if (e != EXSHELLPROC) {
962			commandname = savecmdname;
963			if (flags & EV_EXIT) {
964				exitshell(exitstatus);
965			}
966		}
967		handler = savehandler;
968		if (flags == EV_BACKCMD) {
969			backcmd->buf = memout.buf;
970			backcmd->nleft = memout.nextc - memout.buf;
971			memout.buf = NULL;
972		}
973		if (cmdentry.u.index != EXECCMD &&
974				(e == -1 || e == EXERROR || e == EXEXEC))
975			popredir();
976		if (e != -1) {
977			if ((e != EXERROR && e != EXEXEC)
978			    || cmdentry.special)
979				exraise(e);
980			popfilesupto(savetopfile);
981			if (flags != EV_BACKCMD)
982				FORCEINTON;
983		}
984	} else {
985#ifdef DEBUG
986		trputs("normal command:  ");  trargs(argv);
987#endif
988		redirect(cmd->ncmd.redirect, 0);
989		for (sp = varlist.list ; sp ; sp = sp->next)
990			setvareq(sp->text, VEXPORT|VSTACK);
991		envp = environment();
992		shellexec(argv, envp, path, cmdentry.u.index);
993		/*NOTREACHED*/
994	}
995	goto out;
996
997parent:	/* parent process gets here (if we forked) */
998	if (mode == 0) {	/* argument to fork */
999		INTOFF;
1000		exitstatus = waitforjob(jp, &realstatus);
1001		INTON;
1002		if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1003			evalskip = SKIPBREAK;
1004			skipcount = loopnest;
1005		}
1006	} else if (mode == 2) {
1007		backcmd->fd = pip[0];
1008		close(pip[1]);
1009		backcmd->jp = jp;
1010	}
1011
1012out:
1013	if (lastarg)
1014		setvar("_", lastarg, 0);
1015	if (do_clearcmdentry)
1016		clearcmdentry(0);
1017	popstackmark(&smark);
1018}
1019
1020
1021
1022/*
1023 * Search for a command.  This is called before we fork so that the
1024 * location of the command will be available in the parent as well as
1025 * the child.  The check for "goodname" is an overly conservative
1026 * check that the name will not be subject to expansion.
1027 */
1028
1029STATIC void
1030prehash(union node *n)
1031{
1032	struct cmdentry entry;
1033
1034	if (n && n->type == NCMD && n->ncmd.args)
1035		if (goodname(n->ncmd.args->narg.text))
1036			find_command(n->ncmd.args->narg.text, &entry, 0,
1037				     pathval());
1038}
1039
1040
1041
1042/*
1043 * Builtin commands.  Builtin commands whose functions are closely
1044 * tied to evaluation are implemented here.
1045 */
1046
1047/*
1048 * No command given, a bltin command with no arguments, or a bltin command
1049 * with an invalid name.
1050 */
1051
1052int
1053bltincmd(int argc, char **argv)
1054{
1055	if (argc > 1) {
1056		out2fmt_flush("%s: not found\n", argv[1]);
1057		return 127;
1058	}
1059	/*
1060	 * Preserve exitstatus of a previous possible redirection
1061	 * as POSIX mandates
1062	 */
1063	return exitstatus;
1064}
1065
1066
1067/*
1068 * Handle break and continue commands.  Break, continue, and return are
1069 * all handled by setting the evalskip flag.  The evaluation routines
1070 * above all check this flag, and if it is set they start skipping
1071 * commands rather than executing them.  The variable skipcount is
1072 * the number of loops to break/continue, or the number of function
1073 * levels to return.  (The latter is always 1.)  It should probably
1074 * be an error to break out of more loops than exist, but it isn't
1075 * in the standard shell so we don't make it one here.
1076 */
1077
1078int
1079breakcmd(int argc, char **argv)
1080{
1081	int n = argc > 1 ? number(argv[1]) : 1;
1082
1083	if (n > loopnest)
1084		n = loopnest;
1085	if (n > 0) {
1086		evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1087		skipcount = n;
1088	}
1089	return 0;
1090}
1091
1092/*
1093 * The `command' command.
1094 */
1095int
1096commandcmd(int argc, char **argv)
1097{
1098	const char *path;
1099	int ch;
1100	int cmd = -1;
1101
1102	path = bltinlookup("PATH", 1);
1103
1104	optind = optreset = 1;
1105	opterr = 0;
1106	while ((ch = getopt(argc, argv, "pvV")) != -1) {
1107		switch (ch) {
1108		case 'p':
1109			path = _PATH_STDPATH;
1110			break;
1111		case 'v':
1112			cmd = TYPECMD_SMALLV;
1113			break;
1114		case 'V':
1115			cmd = TYPECMD_BIGV;
1116			break;
1117		case '?':
1118		default:
1119			error("unknown option: -%c", optopt);
1120		}
1121	}
1122	argc -= optind;
1123	argv += optind;
1124
1125	if (cmd != -1) {
1126		if (argc != 1)
1127			error("wrong number of arguments");
1128		return typecmd_impl(2, argv - 1, cmd, path);
1129	}
1130	if (argc != 0)
1131		error("commandcmd() called while it should not be");
1132
1133	/*
1134	 * Do nothing successfully if no command was specified;
1135	 * ksh also does this.
1136	 */
1137	return 0;
1138}
1139
1140
1141/*
1142 * The return command.
1143 */
1144
1145int
1146returncmd(int argc, char **argv)
1147{
1148	int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1149
1150	if (funcnest) {
1151		evalskip = SKIPFUNC;
1152		skipcount = 1;
1153	} else {
1154		/* skip the rest of the file */
1155		evalskip = SKIPFILE;
1156		skipcount = 1;
1157	}
1158	return ret;
1159}
1160
1161
1162int
1163falsecmd(int argc __unused, char **argv __unused)
1164{
1165	return 1;
1166}
1167
1168
1169int
1170truecmd(int argc __unused, char **argv __unused)
1171{
1172	return 0;
1173}
1174
1175
1176int
1177execcmd(int argc, char **argv)
1178{
1179	/*
1180	 * Because we have historically not supported any options,
1181	 * only treat "--" specially.
1182	 */
1183	if (argc > 1 && strcmp(argv[1], "--") == 0)
1184		argc--, argv++;
1185	if (argc > 1) {
1186		struct strlist *sp;
1187
1188		iflag = 0;		/* exit on error */
1189		mflag = 0;
1190		optschanged();
1191		for (sp = cmdenviron; sp ; sp = sp->next)
1192			setvareq(sp->text, VEXPORT|VSTACK);
1193		shellexec(argv + 1, environment(), pathval(), 0);
1194
1195	}
1196	return 0;
1197}
1198
1199
1200int
1201timescmd(int argc __unused, char **argv __unused)
1202{
1203	struct rusage ru;
1204	long shumins, shsmins, chumins, chsmins;
1205	double shusecs, shssecs, chusecs, chssecs;
1206
1207	if (getrusage(RUSAGE_SELF, &ru) < 0)
1208		return 1;
1209	shumins = ru.ru_utime.tv_sec / 60;
1210	shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1211	shsmins = ru.ru_stime.tv_sec / 60;
1212	shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1213	if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1214		return 1;
1215	chumins = ru.ru_utime.tv_sec / 60;
1216	chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1217	chsmins = ru.ru_stime.tv_sec / 60;
1218	chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1219	out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1220	    shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1221	return 0;
1222}
1223