eval.c revision 123996 
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
37#ifndef lint
38#if 0
39static char sccsid[] = "@(#)eval.c	8.9 (Berkeley) 6/8/95";
40#endif
41#endif /* not lint */
42#include <sys/cdefs.h>
43__FBSDID("$FreeBSD: head/bin/sh/eval.c 123996 2003-12-30 15:39:33Z maxim $");
44
45#include <paths.h>
46#include <signal.h>
47#include <stdlib.h>
48#include <unistd.h>
49#include <sys/wait.h> /* For WIFSIGNALED(status) */
50#include <errno.h>
51
52/*
53 * Evaluate a command.
54 */
55
56#include "shell.h"
57#include "nodes.h"
58#include "syntax.h"
59#include "expand.h"
60#include "parser.h"
61#include "jobs.h"
62#include "eval.h"
63#include "builtins.h"
64#include "options.h"
65#include "exec.h"
66#include "redir.h"
67#include "input.h"
68#include "output.h"
69#include "trap.h"
70#include "var.h"
71#include "memalloc.h"
72#include "error.h"
73#include "show.h"
74#include "mystring.h"
75#ifndef NO_HISTORY
76#include "myhistedit.h"
77#endif
78
79
80/* flags in argument to evaltree */
81#define EV_EXIT 01		/* exit after evaluating tree */
82#define EV_TESTED 02		/* exit status is checked; ignore -e flag */
83#define EV_BACKCMD 04		/* command executing within back quotes */
84
85MKINIT int evalskip;		/* set if we are skipping commands */
86STATIC int skipcount;		/* number of levels to skip */
87MKINIT int loopnest;		/* current loop nesting level */
88int funcnest;			/* depth of function calls */
89
90
91char *commandname;
92struct strlist *cmdenviron;
93int exitstatus;			/* exit status of last command */
94int oexitstatus;		/* saved exit status */
95
96
97STATIC void evalloop(union node *);
98STATIC void evalfor(union node *);
99STATIC void evalcase(union node *, int);
100STATIC void evalsubshell(union node *, int);
101STATIC void expredir(union node *);
102STATIC void evalpipe(union node *);
103STATIC void evalcommand(union node *, int, struct backcmd *);
104STATIC void prehash(union node *);
105
106
107/*
108 * Called to reset things after an exception.
109 */
110
111#ifdef mkinit
112INCLUDE "eval.h"
113
114RESET {
115	evalskip = 0;
116	loopnest = 0;
117	funcnest = 0;
118}
119
120SHELLPROC {
121	exitstatus = 0;
122}
123#endif
124
125
126
127/*
128 * The eval command.
129 */
130
131int
132evalcmd(int argc, char **argv)
133{
134        char *p;
135        char *concat;
136        char **ap;
137
138        if (argc > 1) {
139                p = argv[1];
140                if (argc > 2) {
141                        STARTSTACKSTR(concat);
142                        ap = argv + 2;
143                        for (;;) {
144                                while (*p)
145                                        STPUTC(*p++, concat);
146                                if ((p = *ap++) == NULL)
147                                        break;
148                                STPUTC(' ', concat);
149                        }
150                        STPUTC('\0', concat);
151                        p = grabstackstr(concat);
152                }
153                evalstring(p);
154        }
155        return exitstatus;
156}
157
158
159/*
160 * Execute a command or commands contained in a string.
161 */
162
163void
164evalstring(char *s)
165{
166	union node *n;
167	struct stackmark smark;
168
169	setstackmark(&smark);
170	setinputstring(s, 1);
171	while ((n = parsecmd(0)) != NEOF) {
172		evaltree(n, 0);
173		popstackmark(&smark);
174	}
175	popfile();
176	popstackmark(&smark);
177}
178
179
180
181/*
182 * Evaluate a parse tree.  The value is left in the global variable
183 * exitstatus.
184 */
185
186void
187evaltree(union node *n, int flags)
188{
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(0x%lx: %d) called\n", (long)n, n->type));
198	switch (n->type) {
199	case NSEMI:
200		evaltree(n->nbinary.ch1, 0);
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		break;
227	case NBACKGND:
228		evalsubshell(n, flags);
229		break;
230	case NIF: {
231		evaltree(n->nif.test, EV_TESTED);
232		if (evalskip)
233			goto out;
234		if (exitstatus == 0)
235			evaltree(n->nif.ifpart, flags);
236		else if (n->nif.elsepart)
237			evaltree(n->nif.elsepart, flags);
238		else
239			exitstatus = 0;
240		break;
241	}
242	case NWHILE:
243	case NUNTIL:
244		evalloop(n);
245		break;
246	case NFOR:
247		evalfor(n);
248		break;
249	case NCASE:
250		evalcase(n, flags);
251		break;
252	case NDEFUN:
253		defun(n->narg.text, n->narg.next);
254		exitstatus = 0;
255		break;
256	case NNOT:
257		evaltree(n->nnot.com, EV_TESTED);
258		exitstatus = !exitstatus;
259		break;
260
261	case NPIPE:
262		evalpipe(n);
263		break;
264	case NCMD:
265		evalcommand(n, flags, (struct backcmd *)NULL);
266		break;
267	default:
268		out1fmt("Node type = %d\n", n->type);
269		flushout(&output);
270		break;
271	}
272out:
273	if (pendingsigs)
274		dotrap();
275	if ((flags & EV_EXIT) || (eflag && exitstatus
276	    && !(flags & EV_TESTED) && (n->type == NCMD)))
277		exitshell(exitstatus);
278}
279
280
281STATIC void
282evalloop(union node *n)
283{
284	int status;
285
286	loopnest++;
287	status = 0;
288	for (;;) {
289		evaltree(n->nbinary.ch1, EV_TESTED);
290		if (evalskip) {
291skipping:	  if (evalskip == SKIPCONT && --skipcount <= 0) {
292				evalskip = 0;
293				continue;
294			}
295			if (evalskip == SKIPBREAK && --skipcount <= 0)
296				evalskip = 0;
297			break;
298		}
299		if (n->type == NWHILE) {
300			if (exitstatus != 0)
301				break;
302		} else {
303			if (exitstatus == 0)
304				break;
305		}
306		evaltree(n->nbinary.ch2, 0);
307		status = exitstatus;
308		if (evalskip)
309			goto skipping;
310	}
311	loopnest--;
312	exitstatus = status;
313}
314
315
316
317STATIC void
318evalfor(union node *n)
319{
320	struct arglist arglist;
321	union node *argp;
322	struct strlist *sp;
323	struct stackmark smark;
324
325	setstackmark(&smark);
326	arglist.lastp = &arglist.list;
327	for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
328		oexitstatus = exitstatus;
329		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
330		if (evalskip)
331			goto out;
332	}
333	*arglist.lastp = NULL;
334
335	exitstatus = 0;
336	loopnest++;
337	for (sp = arglist.list ; sp ; sp = sp->next) {
338		setvar(n->nfor.var, sp->text, 0);
339		evaltree(n->nfor.body, 0);
340		if (evalskip) {
341			if (evalskip == SKIPCONT && --skipcount <= 0) {
342				evalskip = 0;
343				continue;
344			}
345			if (evalskip == SKIPBREAK && --skipcount <= 0)
346				evalskip = 0;
347			break;
348		}
349	}
350	loopnest--;
351out:
352	popstackmark(&smark);
353}
354
355
356
357STATIC void
358evalcase(union node *n, int flags)
359{
360	union node *cp;
361	union node *patp;
362	struct arglist arglist;
363	struct stackmark smark;
364
365	setstackmark(&smark);
366	arglist.lastp = &arglist.list;
367	oexitstatus = exitstatus;
368	expandarg(n->ncase.expr, &arglist, EXP_TILDE);
369	for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
370		for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
371			if (casematch(patp, arglist.list->text)) {
372				if (evalskip == 0) {
373					evaltree(cp->nclist.body, flags);
374				}
375				goto out;
376			}
377		}
378	}
379out:
380	popstackmark(&smark);
381}
382
383
384
385/*
386 * Kick off a subshell to evaluate a tree.
387 */
388
389STATIC void
390evalsubshell(union node *n, int flags)
391{
392	struct job *jp;
393	int backgnd = (n->type == NBACKGND);
394
395	expredir(n->nredir.redirect);
396	jp = makejob(n, 1);
397	if (forkshell(jp, n, backgnd) == 0) {
398		if (backgnd)
399			flags &=~ EV_TESTED;
400		redirect(n->nredir.redirect, 0);
401		evaltree(n->nredir.n, flags | EV_EXIT);	/* never returns */
402	}
403	if (! backgnd) {
404		INTOFF;
405		exitstatus = waitforjob(jp, (int *)NULL);
406		INTON;
407	}
408}
409
410
411
412/*
413 * Compute the names of the files in a redirection list.
414 */
415
416STATIC void
417expredir(union node *n)
418{
419	union node *redir;
420
421	for (redir = n ; redir ; redir = redir->nfile.next) {
422		struct arglist fn;
423		fn.lastp = &fn.list;
424		oexitstatus = exitstatus;
425		switch (redir->type) {
426		case NFROM:
427		case NTO:
428		case NFROMTO:
429		case NAPPEND:
430		case NCLOBBER:
431			expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
432			redir->nfile.expfname = fn.list->text;
433			break;
434		case NFROMFD:
435		case NTOFD:
436			if (redir->ndup.vname) {
437				expandarg(redir->ndup.vname, &fn, EXP_FULL | EXP_TILDE);
438				fixredir(redir, fn.list->text, 1);
439			}
440			break;
441		}
442	}
443}
444
445
446
447/*
448 * Evaluate a pipeline.  All the processes in the pipeline are children
449 * of the process creating the pipeline.  (This differs from some versions
450 * of the shell, which make the last process in a pipeline the parent
451 * of all the rest.)
452 */
453
454STATIC void
455evalpipe(union node *n)
456{
457	struct job *jp;
458	struct nodelist *lp;
459	int pipelen;
460	int prevfd;
461	int pip[2];
462
463	TRACE(("evalpipe(0x%lx) called\n", (long)n));
464	pipelen = 0;
465	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
466		pipelen++;
467	INTOFF;
468	jp = makejob(n, pipelen);
469	prevfd = -1;
470	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
471		prehash(lp->n);
472		pip[1] = -1;
473		if (lp->next) {
474			if (pipe(pip) < 0) {
475				close(prevfd);
476				error("Pipe call failed: %s", strerror(errno));
477			}
478		}
479		if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
480			INTON;
481			if (prevfd > 0) {
482				close(0);
483				copyfd(prevfd, 0);
484				close(prevfd);
485			}
486			if (pip[1] >= 0) {
487				if (!(prevfd >= 0 && pip[0] == 0))
488					close(pip[0]);
489				if (pip[1] != 1) {
490					close(1);
491					copyfd(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				close(1);
549				copyfd(pip[1], 1);
550				close(pip[1]);
551			}
552			evaltree(n, EV_EXIT);
553		}
554		close(pip[1]);
555		result->fd = pip[0];
556		result->jp = jp;
557	}
558out:
559	popstackmark(&smark);
560	TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
561		result->fd, result->buf, result->nleft, result->jp));
562}
563
564
565
566/*
567 * Execute a simple command.
568 */
569
570STATIC void
571evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
572{
573	struct stackmark smark;
574	union node *argp;
575	struct arglist arglist;
576	struct arglist varlist;
577	char **argv;
578	int argc;
579	char **envp;
580	int varflag;
581	struct strlist *sp;
582	int mode;
583	int pip[2];
584	struct cmdentry cmdentry;
585	struct job *jp;
586	struct jmploc jmploc;
587	struct jmploc *volatile savehandler;
588	char *volatile savecmdname;
589	volatile struct shparam saveparam;
590	struct localvar *volatile savelocalvars;
591	volatile int e;
592	char *lastarg;
593	int realstatus;
594	int do_clearcmdentry;
595#if __GNUC__
596	/* Avoid longjmp clobbering */
597	(void) &argv;
598	(void) &argc;
599	(void) &lastarg;
600	(void) &flags;
601	(void) &do_clearcmdentry;
602#endif
603
604	/* First expand the arguments. */
605	TRACE(("evalcommand(0x%lx, %d) called\n", (long)cmd, flags));
606	setstackmark(&smark);
607	arglist.lastp = &arglist.list;
608	varlist.lastp = &varlist.list;
609	varflag = 1;
610	do_clearcmdentry = 0;
611	oexitstatus = exitstatus;
612	exitstatus = 0;
613	for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
614		char *p = argp->narg.text;
615		if (varflag && is_name(*p)) {
616			do {
617				p++;
618			} while (is_in_name(*p));
619			if (*p == '=') {
620				expandarg(argp, &varlist, EXP_VARTILDE);
621				continue;
622			}
623		}
624		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
625		varflag = 0;
626	}
627	*arglist.lastp = NULL;
628	*varlist.lastp = NULL;
629	expredir(cmd->ncmd.redirect);
630	argc = 0;
631	for (sp = arglist.list ; sp ; sp = sp->next)
632		argc++;
633	argv = stalloc(sizeof (char *) * (argc + 1));
634
635	for (sp = arglist.list ; sp ; sp = sp->next) {
636		TRACE(("evalcommand arg: %s\n", sp->text));
637		*argv++ = sp->text;
638	}
639	*argv = NULL;
640	lastarg = NULL;
641	if (iflag && funcnest == 0 && argc > 0)
642		lastarg = argv[-1];
643	argv -= argc;
644
645	/* Print the command if xflag is set. */
646	if (xflag) {
647		outc('+', &errout);
648		for (sp = varlist.list ; sp ; sp = sp->next) {
649			outc(' ', &errout);
650			out2str(sp->text);
651		}
652		for (sp = arglist.list ; sp ; sp = sp->next) {
653			outc(' ', &errout);
654			out2str(sp->text);
655		}
656		outc('\n', &errout);
657		flushout(&errout);
658	}
659
660	/* Now locate the command. */
661	if (argc == 0) {
662		cmdentry.cmdtype = CMDBUILTIN;
663		cmdentry.u.index = BLTINCMD;
664	} else {
665		static const char PATH[] = "PATH=";
666		char *path = pathval();
667
668		/*
669		 * Modify the command lookup path, if a PATH= assignment
670		 * is present
671		 */
672		for (sp = varlist.list ; sp ; sp = sp->next)
673			if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
674				path = sp->text + sizeof(PATH) - 1;
675				/*
676				 * On `PATH=... command`, we need to make
677				 * sure that the command isn't using the
678				 * non-updated hash table of the outer PATH
679				 * setting and we need to make sure that
680				 * the hash table isn't filled with items
681				 * from the temporary setting.
682				 *
683				 * It would be better to forbit using and
684				 * updating the table while this command
685				 * runs, by the command finding mechanism
686				 * is heavily integrated with hash handling,
687				 * so we just delete the hash before and after
688				 * the command runs. Partly deleting like
689				 * changepatch() does doesn't seem worth the
690				 * bookinging effort, since most such runs add
691				 * directories in front of the new PATH.
692				 */
693				clearcmdentry(0);
694				do_clearcmdentry = 1;
695			}
696
697		find_command(argv[0], &cmdentry, 1, path);
698		if (cmdentry.cmdtype == CMDUNKNOWN) {	/* command not found */
699			exitstatus = 127;
700			flushout(&errout);
701			return;
702		}
703		/* implement the bltin builtin here */
704		if (cmdentry.cmdtype == CMDBUILTIN && cmdentry.u.index == BLTINCMD) {
705			for (;;) {
706				argv++;
707				if (--argc == 0)
708					break;
709				if ((cmdentry.u.index = find_builtin(*argv)) < 0) {
710					outfmt(&errout, "%s: not found\n", *argv);
711					exitstatus = 127;
712					flushout(&errout);
713					return;
714				}
715				if (cmdentry.u.index != BLTINCMD)
716					break;
717			}
718		}
719	}
720
721	/* Fork off a child process if necessary. */
722	if (cmd->ncmd.backgnd
723	 || (cmdentry.cmdtype == CMDNORMAL
724	    && ((flags & EV_EXIT) == 0 || Tflag))
725	 || ((flags & EV_BACKCMD) != 0
726	    && (cmdentry.cmdtype != CMDBUILTIN
727		 || cmdentry.u.index == CDCMD
728		 || cmdentry.u.index == DOTCMD
729		 || cmdentry.u.index == EVALCMD))
730	 || (cmdentry.cmdtype == CMDBUILTIN &&
731	    cmdentry.u.index == COMMANDCMD)) {
732		jp = makejob(cmd, 1);
733		mode = cmd->ncmd.backgnd;
734		if (flags & EV_BACKCMD) {
735			mode = FORK_NOJOB;
736			if (pipe(pip) < 0)
737				error("Pipe call failed: %s", strerror(errno));
738		}
739		if (forkshell(jp, cmd, mode) != 0)
740			goto parent;	/* at end of routine */
741		if (flags & EV_BACKCMD) {
742			FORCEINTON;
743			close(pip[0]);
744			if (pip[1] != 1) {
745				close(1);
746				copyfd(pip[1], 1);
747				close(pip[1]);
748			}
749		}
750		flags |= EV_EXIT;
751	}
752
753	/* This is the child process if a fork occurred. */
754	/* Execute the command. */
755	if (cmdentry.cmdtype == CMDFUNCTION) {
756#ifdef DEBUG
757		trputs("Shell function:  ");  trargs(argv);
758#endif
759		redirect(cmd->ncmd.redirect, REDIR_PUSH);
760		saveparam = shellparam;
761		shellparam.malloc = 0;
762		shellparam.reset = 1;
763		shellparam.nparam = argc - 1;
764		shellparam.p = argv + 1;
765		shellparam.optnext = NULL;
766		INTOFF;
767		savelocalvars = localvars;
768		localvars = NULL;
769		INTON;
770		if (setjmp(jmploc.loc)) {
771			if (exception == EXSHELLPROC)
772				freeparam((struct shparam *)&saveparam);
773			else {
774				freeparam(&shellparam);
775				shellparam = saveparam;
776			}
777			poplocalvars();
778			localvars = savelocalvars;
779			handler = savehandler;
780			longjmp(handler->loc, 1);
781		}
782		savehandler = handler;
783		handler = &jmploc;
784		for (sp = varlist.list ; sp ; sp = sp->next)
785			mklocal(sp->text);
786		funcnest++;
787		if (flags & EV_TESTED)
788			evaltree(cmdentry.u.func, EV_TESTED);
789		else
790			evaltree(cmdentry.u.func, 0);
791		funcnest--;
792		INTOFF;
793		poplocalvars();
794		localvars = savelocalvars;
795		freeparam(&shellparam);
796		shellparam = saveparam;
797		handler = savehandler;
798		popredir();
799		INTON;
800		if (evalskip == SKIPFUNC) {
801			evalskip = 0;
802			skipcount = 0;
803		}
804		if (flags & EV_EXIT)
805			exitshell(exitstatus);
806	} else if (cmdentry.cmdtype == CMDBUILTIN) {
807#ifdef DEBUG
808		trputs("builtin command:  ");  trargs(argv);
809#endif
810		mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
811		if (flags == EV_BACKCMD) {
812			memout.nleft = 0;
813			memout.nextc = memout.buf;
814			memout.bufsize = 64;
815			mode |= REDIR_BACKQ;
816		}
817		redirect(cmd->ncmd.redirect, mode);
818		savecmdname = commandname;
819		cmdenviron = varlist.list;
820		e = -1;
821		if (setjmp(jmploc.loc)) {
822			e = exception;
823			exitstatus = (e == EXINT)? SIGINT+128 : 2;
824			goto cmddone;
825		}
826		savehandler = handler;
827		handler = &jmploc;
828		commandname = argv[0];
829		argptr = argv + 1;
830		optptr = NULL;			/* initialize nextopt */
831		exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
832		flushall();
833cmddone:
834		cmdenviron = NULL;
835		out1 = &output;
836		out2 = &errout;
837		freestdout();
838		if (e != EXSHELLPROC) {
839			commandname = savecmdname;
840			if (flags & EV_EXIT) {
841				exitshell(exitstatus);
842			}
843		}
844		handler = savehandler;
845		if (e != -1) {
846			if ((e != EXERROR && e != EXEXEC)
847			   || cmdentry.u.index == BLTINCMD
848			   || cmdentry.u.index == DOTCMD
849			   || cmdentry.u.index == EVALCMD
850#ifndef NO_HISTORY
851			   || cmdentry.u.index == HISTCMD
852#endif
853			   || cmdentry.u.index == EXECCMD
854			   || cmdentry.u.index == COMMANDCMD)
855				exraise(e);
856			FORCEINTON;
857		}
858		if (cmdentry.u.index != EXECCMD)
859			popredir();
860		if (flags == EV_BACKCMD) {
861			backcmd->buf = memout.buf;
862			backcmd->nleft = memout.nextc - memout.buf;
863			memout.buf = NULL;
864		}
865	} else {
866#ifdef DEBUG
867		trputs("normal command:  ");  trargs(argv);
868#endif
869		clearredir();
870		redirect(cmd->ncmd.redirect, 0);
871		for (sp = varlist.list ; sp ; sp = sp->next)
872			setvareq(sp->text, VEXPORT|VSTACK);
873		envp = environment();
874		shellexec(argv, envp, pathval(), cmdentry.u.index);
875		/*NOTREACHED*/
876	}
877	goto out;
878
879parent:	/* parent process gets here (if we forked) */
880	if (mode == 0) {	/* argument to fork */
881		INTOFF;
882		exitstatus = waitforjob(jp, &realstatus);
883		INTON;
884		if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
885			evalskip = SKIPBREAK;
886			skipcount = loopnest;
887		}
888	} else if (mode == 2) {
889		backcmd->fd = pip[0];
890		close(pip[1]);
891		backcmd->jp = jp;
892	}
893
894out:
895	if (lastarg)
896		setvar("_", lastarg, 0);
897	if (do_clearcmdentry)
898		clearcmdentry(0);
899	popstackmark(&smark);
900}
901
902
903
904/*
905 * Search for a command.  This is called before we fork so that the
906 * location of the command will be available in the parent as well as
907 * the child.  The check for "goodname" is an overly conservative
908 * check that the name will not be subject to expansion.
909 */
910
911STATIC void
912prehash(union node *n)
913{
914	struct cmdentry entry;
915
916	if (n->type == NCMD && n->ncmd.args)
917		if (goodname(n->ncmd.args->narg.text))
918			find_command(n->ncmd.args->narg.text, &entry, 0,
919				     pathval());
920}
921
922
923
924/*
925 * Builtin commands.  Builtin commands whose functions are closely
926 * tied to evaluation are implemented here.
927 */
928
929/*
930 * No command given, or a bltin command with no arguments.  Set the
931 * specified variables.
932 */
933
934int
935bltincmd(int argc __unused, char **argv __unused)
936{
937	listsetvar(cmdenviron);
938	/*
939	 * Preserve exitstatus of a previous possible redirection
940	 * as POSIX mandates
941	 */
942	return exitstatus;
943}
944
945
946/*
947 * Handle break and continue commands.  Break, continue, and return are
948 * all handled by setting the evalskip flag.  The evaluation routines
949 * above all check this flag, and if it is set they start skipping
950 * commands rather than executing them.  The variable skipcount is
951 * the number of loops to break/continue, or the number of function
952 * levels to return.  (The latter is always 1.)  It should probably
953 * be an error to break out of more loops than exist, but it isn't
954 * in the standard shell so we don't make it one here.
955 */
956
957int
958breakcmd(int argc, char **argv)
959{
960	int n = argc > 1 ? number(argv[1]) : 1;
961
962	if (n > loopnest)
963		n = loopnest;
964	if (n > 0) {
965		evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
966		skipcount = n;
967	}
968	return 0;
969}
970
971/*
972 * The `command' command.
973 */
974int
975commandcmd(int argc, char **argv)
976{
977	static char stdpath[] = _PATH_STDPATH;
978	struct jmploc loc, *old;
979	struct strlist *sp;
980	char *path;
981	int ch;
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, "p")) != -1) {
990		switch (ch) {
991		case 'p':
992			path = stdpath;
993			break;
994		case '?':
995		default:
996			error("unknown option: -%c", optopt);
997		}
998	}
999	argc -= optind;
1000	argv += optind;
1001
1002	if (argc != 0) {
1003		old = handler;
1004		handler = &loc;
1005		if (setjmp(handler->loc) == 0)
1006			shellexec(argv, environment(), path, 0);
1007		handler = old;
1008		if (exception == EXEXEC)
1009			exit(exerrno);
1010		exraise(exception);
1011	}
1012
1013	/*
1014	 * Do nothing successfully if no command was specified;
1015	 * ksh also does this.
1016	 */
1017	exit(0);
1018}
1019
1020
1021/*
1022 * The return command.
1023 */
1024
1025int
1026returncmd(int argc, char **argv)
1027{
1028	int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1029
1030	if (funcnest) {
1031		evalskip = SKIPFUNC;
1032		skipcount = 1;
1033	} else {
1034		/* skip the rest of the file */
1035		evalskip = SKIPFILE;
1036		skipcount = 1;
1037	}
1038	return ret;
1039}
1040
1041
1042int
1043falsecmd(int argc __unused, char **argv __unused)
1044{
1045	return 1;
1046}
1047
1048
1049int
1050truecmd(int argc __unused, char **argv __unused)
1051{
1052	return 0;
1053}
1054
1055
1056int
1057execcmd(int argc, char **argv)
1058{
1059	if (argc > 1) {
1060		struct strlist *sp;
1061
1062		iflag = 0;		/* exit on error */
1063		mflag = 0;
1064		optschanged();
1065		for (sp = cmdenviron; sp ; sp = sp->next)
1066			setvareq(sp->text, VEXPORT|VSTACK);
1067		shellexec(argv + 1, environment(), pathval(), 0);
1068
1069	}
1070	return 0;
1071}
1072