eval.c revision 159632 
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 159632 2006-06-15 07:00:49Z stefanf $");
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
77/* flags in argument to evaltree */
78#define EV_EXIT 01		/* exit after evaluating tree */
79#define EV_TESTED 02		/* exit status is checked; ignore -e flag */
80#define EV_BACKCMD 04		/* command executing within back quotes */
81
82MKINIT int evalskip;		/* set if we are skipping commands */
83STATIC int skipcount;		/* number of levels to skip */
84MKINIT int loopnest;		/* current loop nesting level */
85int funcnest;			/* depth of function calls */
86
87
88char *commandname;
89struct strlist *cmdenviron;
90int exitstatus;			/* exit status of last command */
91int oexitstatus;		/* saved exit status */
92
93
94STATIC void evalloop(union node *, int);
95STATIC void evalfor(union node *, int);
96STATIC void evalcase(union node *, int);
97STATIC void evalsubshell(union node *, int);
98STATIC void expredir(union node *);
99STATIC void evalpipe(union node *);
100STATIC void evalcommand(union node *, int, struct backcmd *);
101STATIC void prehash(union node *);
102
103
104/*
105 * Called to reset things after an exception.
106 */
107
108#ifdef mkinit
109INCLUDE "eval.h"
110
111RESET {
112	evalskip = 0;
113	loopnest = 0;
114	funcnest = 0;
115}
116
117SHELLPROC {
118	exitstatus = 0;
119}
120#endif
121
122
123
124/*
125 * The eval command.
126 */
127
128int
129evalcmd(int argc, char **argv)
130{
131        char *p;
132        char *concat;
133        char **ap;
134
135        if (argc > 1) {
136                p = argv[1];
137                if (argc > 2) {
138                        STARTSTACKSTR(concat);
139                        ap = argv + 2;
140                        for (;;) {
141                                while (*p)
142                                        STPUTC(*p++, concat);
143                                if ((p = *ap++) == NULL)
144                                        break;
145                                STPUTC(' ', concat);
146                        }
147                        STPUTC('\0', concat);
148                        p = grabstackstr(concat);
149                }
150                evalstring(p);
151        }
152        return exitstatus;
153}
154
155
156/*
157 * Execute a command or commands contained in a string.
158 */
159
160void
161evalstring(char *s)
162{
163	union node *n;
164	struct stackmark smark;
165
166	setstackmark(&smark);
167	setinputstring(s, 1);
168	while ((n = parsecmd(0)) != NEOF) {
169		evaltree(n, 0);
170		popstackmark(&smark);
171	}
172	popfile();
173	popstackmark(&smark);
174}
175
176
177
178/*
179 * Evaluate a parse tree.  The value is left in the global variable
180 * exitstatus.
181 */
182
183void
184evaltree(union node *n, int flags)
185{
186	int do_etest;
187
188	do_etest = 0;
189	if (n == NULL) {
190		TRACE(("evaltree(NULL) called\n"));
191		exitstatus = 0;
192		goto out;
193	}
194#ifndef NO_HISTORY
195	displayhist = 1;	/* show history substitutions done with fc */
196#endif
197	TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
198	switch (n->type) {
199	case NSEMI:
200		evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
201		if (evalskip)
202			goto out;
203		evaltree(n->nbinary.ch2, flags);
204		break;
205	case NAND:
206		evaltree(n->nbinary.ch1, EV_TESTED);
207		if (evalskip || exitstatus != 0) {
208			goto out;
209		}
210		evaltree(n->nbinary.ch2, flags);
211		break;
212	case NOR:
213		evaltree(n->nbinary.ch1, EV_TESTED);
214		if (evalskip || exitstatus == 0)
215			goto out;
216		evaltree(n->nbinary.ch2, flags);
217		break;
218	case NREDIR:
219		expredir(n->nredir.redirect);
220		redirect(n->nredir.redirect, REDIR_PUSH);
221		evaltree(n->nredir.n, flags);
222		popredir();
223		break;
224	case NSUBSHELL:
225		evalsubshell(n, flags);
226		do_etest = !(flags & EV_TESTED);
227		break;
228	case NBACKGND:
229		evalsubshell(n, flags);
230		break;
231	case NIF: {
232		evaltree(n->nif.test, EV_TESTED);
233		if (evalskip)
234			goto out;
235		if (exitstatus == 0)
236			evaltree(n->nif.ifpart, flags);
237		else if (n->nif.elsepart)
238			evaltree(n->nif.elsepart, flags);
239		else
240			exitstatus = 0;
241		break;
242	}
243	case NWHILE:
244	case NUNTIL:
245		evalloop(n, flags & ~EV_EXIT);
246		break;
247	case NFOR:
248		evalfor(n, flags & ~EV_EXIT);
249		break;
250	case NCASE:
251		evalcase(n, flags);
252		break;
253	case NDEFUN:
254		defun(n->narg.text, n->narg.next);
255		exitstatus = 0;
256		break;
257	case NNOT:
258		evaltree(n->nnot.com, EV_TESTED);
259		exitstatus = !exitstatus;
260		break;
261
262	case NPIPE:
263		evalpipe(n);
264		do_etest = !(flags & EV_TESTED);
265		break;
266	case NCMD:
267		evalcommand(n, flags, (struct backcmd *)NULL);
268		do_etest = !(flags & EV_TESTED);
269		break;
270	default:
271		out1fmt("Node type = %d\n", n->type);
272		flushout(&output);
273		break;
274	}
275out:
276	if (pendingsigs)
277		dotrap();
278	if ((flags & EV_EXIT) || (eflag && exitstatus != 0 && do_etest))
279		exitshell(exitstatus);
280}
281
282
283STATIC void
284evalloop(union node *n, int flags)
285{
286	int status;
287
288	loopnest++;
289	status = 0;
290	for (;;) {
291		evaltree(n->nbinary.ch1, EV_TESTED);
292		if (evalskip) {
293skipping:	  if (evalskip == SKIPCONT && --skipcount <= 0) {
294				evalskip = 0;
295				continue;
296			}
297			if (evalskip == SKIPBREAK && --skipcount <= 0)
298				evalskip = 0;
299			break;
300		}
301		if (n->type == NWHILE) {
302			if (exitstatus != 0)
303				break;
304		} else {
305			if (exitstatus == 0)
306				break;
307		}
308		evaltree(n->nbinary.ch2, flags);
309		status = exitstatus;
310		if (evalskip)
311			goto skipping;
312	}
313	loopnest--;
314	exitstatus = status;
315}
316
317
318
319STATIC void
320evalfor(union node *n, int flags)
321{
322	struct arglist arglist;
323	union node *argp;
324	struct strlist *sp;
325	struct stackmark smark;
326
327	setstackmark(&smark);
328	arglist.lastp = &arglist.list;
329	for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
330		oexitstatus = exitstatus;
331		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
332		if (evalskip)
333			goto out;
334	}
335	*arglist.lastp = NULL;
336
337	exitstatus = 0;
338	loopnest++;
339	for (sp = arglist.list ; sp ; sp = sp->next) {
340		setvar(n->nfor.var, sp->text, 0);
341		evaltree(n->nfor.body, flags);
342		if (evalskip) {
343			if (evalskip == SKIPCONT && --skipcount <= 0) {
344				evalskip = 0;
345				continue;
346			}
347			if (evalskip == SKIPBREAK && --skipcount <= 0)
348				evalskip = 0;
349			break;
350		}
351	}
352	loopnest--;
353out:
354	popstackmark(&smark);
355}
356
357
358
359STATIC void
360evalcase(union node *n, int flags)
361{
362	union node *cp;
363	union node *patp;
364	struct arglist arglist;
365	struct stackmark smark;
366
367	setstackmark(&smark);
368	arglist.lastp = &arglist.list;
369	oexitstatus = exitstatus;
370	expandarg(n->ncase.expr, &arglist, EXP_TILDE);
371	for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
372		for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
373			if (casematch(patp, arglist.list->text)) {
374				if (evalskip == 0) {
375					evaltree(cp->nclist.body, flags);
376				}
377				goto out;
378			}
379		}
380	}
381out:
382	popstackmark(&smark);
383}
384
385
386
387/*
388 * Kick off a subshell to evaluate a tree.
389 */
390
391STATIC void
392evalsubshell(union node *n, int flags)
393{
394	struct job *jp;
395	int backgnd = (n->type == NBACKGND);
396
397	expredir(n->nredir.redirect);
398	jp = makejob(n, 1);
399	if (forkshell(jp, n, backgnd) == 0) {
400		if (backgnd)
401			flags &=~ EV_TESTED;
402		redirect(n->nredir.redirect, 0);
403		evaltree(n->nredir.n, flags | EV_EXIT);	/* never returns */
404	}
405	if (! backgnd) {
406		INTOFF;
407		exitstatus = waitforjob(jp, (int *)NULL);
408		INTON;
409	}
410}
411
412
413
414/*
415 * Compute the names of the files in a redirection list.
416 */
417
418STATIC void
419expredir(union node *n)
420{
421	union node *redir;
422
423	for (redir = n ; redir ; redir = redir->nfile.next) {
424		struct arglist fn;
425		fn.lastp = &fn.list;
426		oexitstatus = exitstatus;
427		switch (redir->type) {
428		case NFROM:
429		case NTO:
430		case NFROMTO:
431		case NAPPEND:
432		case NCLOBBER:
433			expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
434			redir->nfile.expfname = fn.list->text;
435			break;
436		case NFROMFD:
437		case NTOFD:
438			if (redir->ndup.vname) {
439				expandarg(redir->ndup.vname, &fn, EXP_FULL | EXP_TILDE);
440				fixredir(redir, fn.list->text, 1);
441			}
442			break;
443		}
444	}
445}
446
447
448
449/*
450 * Evaluate a pipeline.  All the processes in the pipeline are children
451 * of the process creating the pipeline.  (This differs from some versions
452 * of the shell, which make the last process in a pipeline the parent
453 * of all the rest.)
454 */
455
456STATIC void
457evalpipe(union node *n)
458{
459	struct job *jp;
460	struct nodelist *lp;
461	int pipelen;
462	int prevfd;
463	int pip[2];
464
465	TRACE(("evalpipe(%p) called\n", (void *)n));
466	pipelen = 0;
467	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
468		pipelen++;
469	INTOFF;
470	jp = makejob(n, pipelen);
471	prevfd = -1;
472	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
473		prehash(lp->n);
474		pip[1] = -1;
475		if (lp->next) {
476			if (pipe(pip) < 0) {
477				close(prevfd);
478				error("Pipe call failed: %s", strerror(errno));
479			}
480		}
481		if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
482			INTON;
483			if (prevfd > 0) {
484				dup2(prevfd, 0);
485				close(prevfd);
486			}
487			if (pip[1] >= 0) {
488				if (!(prevfd >= 0 && pip[0] == 0))
489					close(pip[0]);
490				if (pip[1] != 1) {
491					dup2(pip[1], 1);
492					close(pip[1]);
493				}
494			}
495			evaltree(lp->n, EV_EXIT);
496		}
497		if (prevfd >= 0)
498			close(prevfd);
499		prevfd = pip[0];
500		close(pip[1]);
501	}
502	INTON;
503	if (n->npipe.backgnd == 0) {
504		INTOFF;
505		exitstatus = waitforjob(jp, (int *)NULL);
506		TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
507		INTON;
508	}
509}
510
511
512
513/*
514 * Execute a command inside back quotes.  If it's a builtin command, we
515 * want to save its output in a block obtained from malloc.  Otherwise
516 * we fork off a subprocess and get the output of the command via a pipe.
517 * Should be called with interrupts off.
518 */
519
520void
521evalbackcmd(union node *n, struct backcmd *result)
522{
523	int pip[2];
524	struct job *jp;
525	struct stackmark smark;		/* unnecessary */
526
527	setstackmark(&smark);
528	result->fd = -1;
529	result->buf = NULL;
530	result->nleft = 0;
531	result->jp = NULL;
532	if (n == NULL) {
533		exitstatus = 0;
534		goto out;
535	}
536	if (n->type == NCMD) {
537		exitstatus = oexitstatus;
538		evalcommand(n, EV_BACKCMD, result);
539	} else {
540		exitstatus = 0;
541		if (pipe(pip) < 0)
542			error("Pipe call failed: %s", strerror(errno));
543		jp = makejob(n, 1);
544		if (forkshell(jp, n, FORK_NOJOB) == 0) {
545			FORCEINTON;
546			close(pip[0]);
547			if (pip[1] != 1) {
548				dup2(pip[1], 1);
549				close(pip[1]);
550			}
551			evaltree(n, EV_EXIT);
552		}
553		close(pip[1]);
554		result->fd = pip[0];
555		result->jp = jp;
556	}
557out:
558	popstackmark(&smark);
559	TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
560		result->fd, result->buf, result->nleft, result->jp));
561}
562
563
564
565/*
566 * Execute a simple command.
567 */
568
569STATIC void
570evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
571{
572	struct stackmark smark;
573	union node *argp;
574	struct arglist arglist;
575	struct arglist varlist;
576	char **argv;
577	int argc;
578	char **envp;
579	int varflag;
580	struct strlist *sp;
581	int mode;
582	int pip[2];
583	struct cmdentry cmdentry;
584	struct job *jp;
585	struct jmploc jmploc;
586	struct jmploc *volatile savehandler;
587	char *volatile savecmdname;
588	volatile struct shparam saveparam;
589	struct localvar *volatile savelocalvars;
590	volatile int e;
591	char *lastarg;
592	int realstatus;
593	int do_clearcmdentry;
594#if __GNUC__
595	/* Avoid longjmp clobbering */
596	(void) &argv;
597	(void) &argc;
598	(void) &lastarg;
599	(void) &flags;
600	(void) &do_clearcmdentry;
601#endif
602
603	/* First expand the arguments. */
604	TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
605	setstackmark(&smark);
606	arglist.lastp = &arglist.list;
607	varlist.lastp = &varlist.list;
608	varflag = 1;
609	do_clearcmdentry = 0;
610	oexitstatus = exitstatus;
611	exitstatus = 0;
612	for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
613		char *p = argp->narg.text;
614		if (varflag && is_name(*p)) {
615			do {
616				p++;
617			} while (is_in_name(*p));
618			if (*p == '=') {
619				expandarg(argp, &varlist, EXP_VARTILDE);
620				continue;
621			}
622		}
623		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
624		varflag = 0;
625	}
626	*arglist.lastp = NULL;
627	*varlist.lastp = NULL;
628	expredir(cmd->ncmd.redirect);
629	argc = 0;
630	for (sp = arglist.list ; sp ; sp = sp->next)
631		argc++;
632	argv = stalloc(sizeof (char *) * (argc + 1));
633
634	for (sp = arglist.list ; sp ; sp = sp->next) {
635		TRACE(("evalcommand arg: %s\n", sp->text));
636		*argv++ = sp->text;
637	}
638	*argv = NULL;
639	lastarg = NULL;
640	if (iflag && funcnest == 0 && argc > 0)
641		lastarg = argv[-1];
642	argv -= argc;
643
644	/* Print the command if xflag is set. */
645	if (xflag) {
646		char sep = 0;
647		out2str(ps4val());
648		for (sp = varlist.list ; sp ; sp = sp->next) {
649			if (sep != 0)
650				outc(' ', &errout);
651			out2str(sp->text);
652			sep = ' ';
653		}
654		for (sp = arglist.list ; sp ; sp = sp->next) {
655			if (sep != 0)
656				outc(' ', &errout);
657			out2str(sp->text);
658			sep = ' ';
659		}
660		outc('\n', &errout);
661		flushout(&errout);
662	}
663
664	/* Now locate the command. */
665	if (argc == 0) {
666		/* Variable assignment(s) without command */
667		cmdentry.cmdtype = CMDBUILTIN;
668		cmdentry.u.index = BLTINCMD;
669		cmdentry.special = 1;
670	} else {
671		static const char PATH[] = "PATH=";
672		char *path = pathval();
673
674		/*
675		 * Modify the command lookup path, if a PATH= assignment
676		 * is present
677		 */
678		for (sp = varlist.list ; sp ; sp = sp->next)
679			if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
680				path = sp->text + sizeof(PATH) - 1;
681				/*
682				 * On `PATH=... command`, we need to make
683				 * sure that the command isn't using the
684				 * non-updated hash table of the outer PATH
685				 * setting and we need to make sure that
686				 * the hash table isn't filled with items
687				 * from the temporary setting.
688				 *
689				 * It would be better to forbit using and
690				 * updating the table while this command
691				 * runs, by the command finding mechanism
692				 * is heavily integrated with hash handling,
693				 * so we just delete the hash before and after
694				 * the command runs. Partly deleting like
695				 * changepatch() does doesn't seem worth the
696				 * bookinging effort, since most such runs add
697				 * directories in front of the new PATH.
698				 */
699				clearcmdentry(0);
700				do_clearcmdentry = 1;
701			}
702
703		find_command(argv[0], &cmdentry, 1, path);
704		if (cmdentry.cmdtype == CMDUNKNOWN) {	/* command not found */
705			exitstatus = 127;
706			flushout(&errout);
707			return;
708		}
709		/* implement the bltin builtin here */
710		if (cmdentry.cmdtype == CMDBUILTIN && cmdentry.u.index == BLTINCMD) {
711			for (;;) {
712				argv++;
713				if (--argc == 0)
714					break;
715				if ((cmdentry.u.index = find_builtin(*argv,
716				    &cmdentry.special)) < 0) {
717					outfmt(&errout, "%s: not found\n", *argv);
718					exitstatus = 127;
719					flushout(&errout);
720					return;
721				}
722				if (cmdentry.u.index != BLTINCMD)
723					break;
724			}
725		}
726	}
727
728	/* Fork off a child process if necessary. */
729	if (cmd->ncmd.backgnd
730	 || (cmdentry.cmdtype == CMDNORMAL
731	    && ((flags & EV_EXIT) == 0 || Tflag))
732	 || ((flags & EV_BACKCMD) != 0
733	    && (cmdentry.cmdtype != CMDBUILTIN
734		 || cmdentry.u.index == CDCMD
735		 || cmdentry.u.index == DOTCMD
736		 || cmdentry.u.index == EVALCMD))
737	 || (cmdentry.cmdtype == CMDBUILTIN &&
738	    cmdentry.u.index == COMMANDCMD)) {
739		jp = makejob(cmd, 1);
740		mode = cmd->ncmd.backgnd;
741		if (flags & EV_BACKCMD) {
742			mode = FORK_NOJOB;
743			if (pipe(pip) < 0)
744				error("Pipe call failed: %s", strerror(errno));
745		}
746		if (forkshell(jp, cmd, mode) != 0)
747			goto parent;	/* at end of routine */
748		if (flags & EV_BACKCMD) {
749			FORCEINTON;
750			close(pip[0]);
751			if (pip[1] != 1) {
752				dup2(pip[1], 1);
753				close(pip[1]);
754			}
755		}
756		flags |= EV_EXIT;
757	}
758
759	/* This is the child process if a fork occurred. */
760	/* Execute the command. */
761	if (cmdentry.cmdtype == CMDFUNCTION) {
762#ifdef DEBUG
763		trputs("Shell function:  ");  trargs(argv);
764#endif
765		redirect(cmd->ncmd.redirect, REDIR_PUSH);
766		saveparam = shellparam;
767		shellparam.malloc = 0;
768		shellparam.reset = 1;
769		shellparam.nparam = argc - 1;
770		shellparam.p = argv + 1;
771		shellparam.optnext = NULL;
772		INTOFF;
773		savelocalvars = localvars;
774		localvars = NULL;
775		INTON;
776		if (setjmp(jmploc.loc)) {
777			if (exception == EXSHELLPROC)
778				freeparam((struct shparam *)&saveparam);
779			else {
780				freeparam(&shellparam);
781				shellparam = saveparam;
782			}
783			poplocalvars();
784			localvars = savelocalvars;
785			handler = savehandler;
786			longjmp(handler->loc, 1);
787		}
788		savehandler = handler;
789		handler = &jmploc;
790		for (sp = varlist.list ; sp ; sp = sp->next)
791			mklocal(sp->text);
792		funcnest++;
793		if (flags & EV_TESTED)
794			evaltree(cmdentry.u.func, EV_TESTED);
795		else
796			evaltree(cmdentry.u.func, 0);
797		funcnest--;
798		INTOFF;
799		poplocalvars();
800		localvars = savelocalvars;
801		freeparam(&shellparam);
802		shellparam = saveparam;
803		handler = savehandler;
804		popredir();
805		INTON;
806		if (evalskip == SKIPFUNC) {
807			evalskip = 0;
808			skipcount = 0;
809		}
810		if (flags & EV_EXIT)
811			exitshell(exitstatus);
812	} else if (cmdentry.cmdtype == CMDBUILTIN) {
813#ifdef DEBUG
814		trputs("builtin command:  ");  trargs(argv);
815#endif
816		mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
817		if (flags == EV_BACKCMD) {
818			memout.nleft = 0;
819			memout.nextc = memout.buf;
820			memout.bufsize = 64;
821			mode |= REDIR_BACKQ;
822		}
823		savecmdname = commandname;
824		cmdenviron = varlist.list;
825		e = -1;
826		if (setjmp(jmploc.loc)) {
827			e = exception;
828			exitstatus = (e == EXINT)? SIGINT+128 : 2;
829			goto cmddone;
830		}
831		savehandler = handler;
832		handler = &jmploc;
833		redirect(cmd->ncmd.redirect, mode);
834		if (cmdentry.special)
835			listsetvar(cmdenviron);
836		commandname = argv[0];
837		argptr = argv + 1;
838		optptr = NULL;			/* initialize nextopt */
839		exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
840		flushall();
841cmddone:
842		cmdenviron = NULL;
843		out1 = &output;
844		out2 = &errout;
845		freestdout();
846		if (e != EXSHELLPROC) {
847			commandname = savecmdname;
848			if (flags & EV_EXIT) {
849				exitshell(exitstatus);
850			}
851		}
852		handler = savehandler;
853		if (e != -1) {
854			if ((e != EXERROR && e != EXEXEC)
855			    || cmdentry.special)
856				exraise(e);
857			FORCEINTON;
858		}
859		if (cmdentry.u.index != EXECCMD)
860			popredir();
861		if (flags == EV_BACKCMD) {
862			backcmd->buf = memout.buf;
863			backcmd->nleft = memout.nextc - memout.buf;
864			memout.buf = NULL;
865		}
866	} else {
867#ifdef DEBUG
868		trputs("normal command:  ");  trargs(argv);
869#endif
870		clearredir();
871		redirect(cmd->ncmd.redirect, 0);
872		for (sp = varlist.list ; sp ; sp = sp->next)
873			setvareq(sp->text, VEXPORT|VSTACK);
874		envp = environment();
875		shellexec(argv, envp, pathval(), cmdentry.u.index);
876		/*NOTREACHED*/
877	}
878	goto out;
879
880parent:	/* parent process gets here (if we forked) */
881	if (mode == 0) {	/* argument to fork */
882		INTOFF;
883		exitstatus = waitforjob(jp, &realstatus);
884		INTON;
885		if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
886			evalskip = SKIPBREAK;
887			skipcount = loopnest;
888		}
889	} else if (mode == 2) {
890		backcmd->fd = pip[0];
891		close(pip[1]);
892		backcmd->jp = jp;
893	}
894
895out:
896	if (lastarg)
897		setvar("_", lastarg, 0);
898	if (do_clearcmdentry)
899		clearcmdentry(0);
900	popstackmark(&smark);
901}
902
903
904
905/*
906 * Search for a command.  This is called before we fork so that the
907 * location of the command will be available in the parent as well as
908 * the child.  The check for "goodname" is an overly conservative
909 * check that the name will not be subject to expansion.
910 */
911
912STATIC void
913prehash(union node *n)
914{
915	struct cmdentry entry;
916
917	if (n->type == NCMD && n->ncmd.args)
918		if (goodname(n->ncmd.args->narg.text))
919			find_command(n->ncmd.args->narg.text, &entry, 0,
920				     pathval());
921}
922
923
924
925/*
926 * Builtin commands.  Builtin commands whose functions are closely
927 * tied to evaluation are implemented here.
928 */
929
930/*
931 * No command given, or a bltin command with no arguments.
932 */
933
934int
935bltincmd(int argc __unused, char **argv __unused)
936{
937	/*
938	 * Preserve exitstatus of a previous possible redirection
939	 * as POSIX mandates
940	 */
941	return exitstatus;
942}
943
944
945/*
946 * Handle break and continue commands.  Break, continue, and return are
947 * all handled by setting the evalskip flag.  The evaluation routines
948 * above all check this flag, and if it is set they start skipping
949 * commands rather than executing them.  The variable skipcount is
950 * the number of loops to break/continue, or the number of function
951 * levels to return.  (The latter is always 1.)  It should probably
952 * be an error to break out of more loops than exist, but it isn't
953 * in the standard shell so we don't make it one here.
954 */
955
956int
957breakcmd(int argc, char **argv)
958{
959	int n = argc > 1 ? number(argv[1]) : 1;
960
961	if (n > loopnest)
962		n = loopnest;
963	if (n > 0) {
964		evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
965		skipcount = n;
966	}
967	return 0;
968}
969
970/*
971 * The `command' command.
972 */
973int
974commandcmd(int argc, char **argv)
975{
976	static char stdpath[] = _PATH_STDPATH;
977	struct jmploc loc, *old;
978	struct strlist *sp;
979	char *path;
980	int ch;
981	int cmd = -1;
982
983	for (sp = cmdenviron; sp ; sp = sp->next)
984		setvareq(sp->text, VEXPORT|VSTACK);
985	path = pathval();
986
987	optind = optreset = 1;
988	opterr = 0;
989	while ((ch = getopt(argc, argv, "pvV")) != -1) {
990		switch (ch) {
991		case 'p':
992			path = stdpath;
993			break;
994		case 'v':
995			cmd = TYPECMD_SMALLV;
996			break;
997		case 'V':
998			cmd = TYPECMD_BIGV;
999			break;
1000		case '?':
1001		default:
1002			error("unknown option: -%c", optopt);
1003		}
1004	}
1005	argc -= optind;
1006	argv += optind;
1007
1008	if (cmd != -1) {
1009		if (argc != 1)
1010			error("wrong number of arguments");
1011		return typecmd_impl(2, argv - 1, cmd);
1012	}
1013	if (argc != 0) {
1014		old = handler;
1015		handler = &loc;
1016		if (setjmp(handler->loc) == 0)
1017			shellexec(argv, environment(), path, 0);
1018		handler = old;
1019		if (exception == EXEXEC)
1020			exit(exerrno);
1021		exraise(exception);
1022	}
1023
1024	/*
1025	 * Do nothing successfully if no command was specified;
1026	 * ksh also does this.
1027	 */
1028	exit(0);
1029}
1030
1031
1032/*
1033 * The return command.
1034 */
1035
1036int
1037returncmd(int argc, char **argv)
1038{
1039	int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1040
1041	if (funcnest) {
1042		evalskip = SKIPFUNC;
1043		skipcount = 1;
1044	} else {
1045		/* skip the rest of the file */
1046		evalskip = SKIPFILE;
1047		skipcount = 1;
1048	}
1049	return ret;
1050}
1051
1052
1053int
1054falsecmd(int argc __unused, char **argv __unused)
1055{
1056	return 1;
1057}
1058
1059
1060int
1061truecmd(int argc __unused, char **argv __unused)
1062{
1063	return 0;
1064}
1065
1066
1067int
1068execcmd(int argc, char **argv)
1069{
1070	if (argc > 1) {
1071		struct strlist *sp;
1072
1073		iflag = 0;		/* exit on error */
1074		mflag = 0;
1075		optschanged();
1076		for (sp = cmdenviron; sp ; sp = sp->next)
1077			setvareq(sp->text, VEXPORT|VSTACK);
1078		shellexec(argv + 1, environment(), pathval(), 0);
1079
1080	}
1081	return 0;
1082}
1083
1084
1085int
1086timescmd(int argc __unused, char **argv __unused)
1087{
1088	struct rusage ru;
1089	long shumins, shsmins, chumins, chsmins;
1090	double shusecs, shssecs, chusecs, chssecs;
1091
1092	if (getrusage(RUSAGE_SELF, &ru) < 0)
1093		return 1;
1094	shumins = ru.ru_utime.tv_sec / 60;
1095	shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1096	shsmins = ru.ru_stime.tv_sec / 60;
1097	shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1098	if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1099		return 1;
1100	chumins = ru.ru_utime.tv_sec / 60;
1101	chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1102	chsmins = ru.ru_stime.tv_sec / 60;
1103	chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1104	out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1105	    shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1106	return 0;
1107}
1108