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. 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("$FreeBSD$");
40
41#include <paths.h>
42#include <signal.h>
43#include <stdlib.h>
44#include <unistd.h>
45#include <sys/resource.h>
46#include <errno.h>
47
48/*
49 * Evaluate a command.
50 */
51
52#include "shell.h"
53#include "nodes.h"
54#include "syntax.h"
55#include "expand.h"
56#include "parser.h"
57#include "jobs.h"
58#include "eval.h"
59#include "builtins.h"
60#include "options.h"
61#include "exec.h"
62#include "redir.h"
63#include "input.h"
64#include "output.h"
65#include "trap.h"
66#include "var.h"
67#include "memalloc.h"
68#include "error.h"
69#include "show.h"
70#include "mystring.h"
71#ifndef NO_HISTORY
72#include "myhistedit.h"
73#endif
74
75
76int evalskip;			/* set if we are skipping commands */
77int skipcount;			/* number of levels to skip */
78static int loopnest;		/* current loop nesting level */
79int funcnest;			/* depth of function calls */
80static int builtin_flags;	/* evalcommand flags for builtins */
81
82
83char *commandname;
84struct arglist *cmdenviron;
85int exitstatus;			/* exit status of last command */
86int oexitstatus;		/* saved exit status */
87
88
89static void evalloop(union node *, int);
90static void evalfor(union node *, int);
91static union node *evalcase(union node *);
92static void evalsubshell(union node *, int);
93static void evalredir(union node *, int);
94static void exphere(union node *, struct arglist *);
95static void expredir(union node *);
96static void evalpipe(union node *);
97static int is_valid_fast_cmdsubst(union node *n);
98static void evalcommand(union node *, int, struct backcmd *);
99static void prehash(union node *);
100
101
102/*
103 * Called to reset things after an exception.
104 */
105
106void
107reseteval(void)
108{
109	evalskip = 0;
110	loopnest = 0;
111}
112
113
114/*
115 * The eval command.
116 */
117
118int
119evalcmd(int argc, char **argv)
120{
121        char *p;
122        char *concat;
123        char **ap;
124
125        if (argc > 1) {
126                p = argv[1];
127                if (argc > 2) {
128                        STARTSTACKSTR(concat);
129                        ap = argv + 2;
130                        for (;;) {
131                                STPUTS(p, concat);
132                                if ((p = *ap++) == NULL)
133                                        break;
134                                STPUTC(' ', concat);
135                        }
136                        STPUTC('\0', concat);
137                        p = grabstackstr(concat);
138                }
139                evalstring(p, builtin_flags);
140        } else
141                exitstatus = 0;
142        return exitstatus;
143}
144
145
146/*
147 * Execute a command or commands contained in a string.
148 */
149
150void
151evalstring(const char *s, int flags)
152{
153	union node *n;
154	struct stackmark smark;
155	int flags_exit;
156	int any;
157
158	flags_exit = flags & EV_EXIT;
159	flags &= ~EV_EXIT;
160	any = 0;
161	setstackmark(&smark);
162	setinputstring(s, 1);
163	while ((n = parsecmd(0)) != NEOF) {
164		if (n != NULL && !nflag) {
165			if (flags_exit && preadateof())
166				evaltree(n, flags | EV_EXIT);
167			else
168				evaltree(n, flags);
169			any = 1;
170			if (evalskip)
171				break;
172		}
173		popstackmark(&smark);
174		setstackmark(&smark);
175	}
176	popfile();
177	popstackmark(&smark);
178	if (!any)
179		exitstatus = 0;
180	if (flags_exit)
181		exraise(EXEXIT);
182}
183
184
185/*
186 * Evaluate a parse tree.  The value is left in the global variable
187 * exitstatus.
188 */
189
190void
191evaltree(union node *n, int flags)
192{
193	int do_etest;
194	union node *next;
195	struct stackmark smark;
196
197	setstackmark(&smark);
198	do_etest = 0;
199	if (n == NULL) {
200		TRACE(("evaltree(NULL) called\n"));
201		exitstatus = 0;
202		goto out;
203	}
204	do {
205		next = NULL;
206#ifndef NO_HISTORY
207		displayhist = 1;	/* show history substitutions done with fc */
208#endif
209		TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
210		switch (n->type) {
211		case NSEMI:
212			evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
213			if (evalskip)
214				goto out;
215			next = n->nbinary.ch2;
216			break;
217		case NAND:
218			evaltree(n->nbinary.ch1, EV_TESTED);
219			if (evalskip || exitstatus != 0) {
220				goto out;
221			}
222			next = n->nbinary.ch2;
223			break;
224		case NOR:
225			evaltree(n->nbinary.ch1, EV_TESTED);
226			if (evalskip || exitstatus == 0)
227				goto out;
228			next = n->nbinary.ch2;
229			break;
230		case NREDIR:
231			evalredir(n, flags);
232			break;
233		case NSUBSHELL:
234			evalsubshell(n, flags);
235			do_etest = !(flags & EV_TESTED);
236			break;
237		case NBACKGND:
238			evalsubshell(n, flags);
239			break;
240		case NIF: {
241			evaltree(n->nif.test, EV_TESTED);
242			if (evalskip)
243				goto out;
244			if (exitstatus == 0)
245				next = n->nif.ifpart;
246			else if (n->nif.elsepart)
247				next = n->nif.elsepart;
248			else
249				exitstatus = 0;
250			break;
251		}
252		case NWHILE:
253		case NUNTIL:
254			evalloop(n, flags & ~EV_EXIT);
255			break;
256		case NFOR:
257			evalfor(n, flags & ~EV_EXIT);
258			break;
259		case NCASE:
260			next = evalcase(n);
261			break;
262		case NCLIST:
263			next = n->nclist.body;
264			break;
265		case NCLISTFALLTHRU:
266			if (n->nclist.body) {
267				evaltree(n->nclist.body, flags & ~EV_EXIT);
268				if (evalskip)
269					goto out;
270			}
271			next = n->nclist.next;
272			break;
273		case NDEFUN:
274			defun(n->narg.text, n->narg.next);
275			exitstatus = 0;
276			break;
277		case NNOT:
278			evaltree(n->nnot.com, EV_TESTED);
279			if (evalskip)
280				goto out;
281			exitstatus = !exitstatus;
282			break;
283
284		case NPIPE:
285			evalpipe(n);
286			do_etest = !(flags & EV_TESTED);
287			break;
288		case NCMD:
289			evalcommand(n, flags, (struct backcmd *)NULL);
290			do_etest = !(flags & EV_TESTED);
291			break;
292		default:
293			out1fmt("Node type = %d\n", n->type);
294			flushout(&output);
295			break;
296		}
297		n = next;
298		popstackmark(&smark);
299		setstackmark(&smark);
300	} while (n != NULL);
301out:
302	popstackmark(&smark);
303	if (pendingsig)
304		dotrap();
305	if (eflag && exitstatus != 0 && do_etest)
306		exitshell(exitstatus);
307	if (flags & EV_EXIT)
308		exraise(EXEXIT);
309}
310
311
312static void
313evalloop(union node *n, int flags)
314{
315	int status;
316
317	loopnest++;
318	status = 0;
319	for (;;) {
320		if (!evalskip)
321			evaltree(n->nbinary.ch1, EV_TESTED);
322		if (evalskip) {
323			if (evalskip == SKIPCONT && --skipcount <= 0) {
324				evalskip = 0;
325				continue;
326			}
327			if (evalskip == SKIPBREAK && --skipcount <= 0)
328				evalskip = 0;
329			if (evalskip == SKIPRETURN)
330				status = exitstatus;
331			break;
332		}
333		if (n->type == NWHILE) {
334			if (exitstatus != 0)
335				break;
336		} else {
337			if (exitstatus == 0)
338				break;
339		}
340		evaltree(n->nbinary.ch2, flags);
341		status = exitstatus;
342	}
343	loopnest--;
344	exitstatus = status;
345}
346
347
348
349static void
350evalfor(union node *n, int flags)
351{
352	struct arglist arglist;
353	union node *argp;
354	int i;
355	int status;
356
357	emptyarglist(&arglist);
358	for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
359		oexitstatus = exitstatus;
360		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
361	}
362
363	loopnest++;
364	status = 0;
365	for (i = 0; i < arglist.count; i++) {
366		setvar(n->nfor.var, arglist.args[i], 0);
367		evaltree(n->nfor.body, flags);
368		status = exitstatus;
369		if (evalskip) {
370			if (evalskip == SKIPCONT && --skipcount <= 0) {
371				evalskip = 0;
372				continue;
373			}
374			if (evalskip == SKIPBREAK && --skipcount <= 0)
375				evalskip = 0;
376			break;
377		}
378	}
379	loopnest--;
380	exitstatus = status;
381}
382
383
384/*
385 * Evaluate a case statement, returning the selected tree.
386 *
387 * The exit status needs care to get right.
388 */
389
390static union node *
391evalcase(union node *n)
392{
393	union node *cp;
394	union node *patp;
395	struct arglist arglist;
396
397	emptyarglist(&arglist);
398	oexitstatus = exitstatus;
399	expandarg(n->ncase.expr, &arglist, EXP_TILDE);
400	for (cp = n->ncase.cases ; cp ; cp = cp->nclist.next) {
401		for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
402			if (casematch(patp, arglist.args[0])) {
403				while (cp->nclist.next &&
404				    cp->type == NCLISTFALLTHRU &&
405				    cp->nclist.body == NULL)
406					cp = cp->nclist.next;
407				if (cp->nclist.next &&
408				    cp->type == NCLISTFALLTHRU)
409					return (cp);
410				if (cp->nclist.body == NULL)
411					exitstatus = 0;
412				return (cp->nclist.body);
413			}
414		}
415	}
416	exitstatus = 0;
417	return (NULL);
418}
419
420
421
422/*
423 * Kick off a subshell to evaluate a tree.
424 */
425
426static void
427evalsubshell(union node *n, int flags)
428{
429	struct job *jp;
430	int backgnd = (n->type == NBACKGND);
431
432	oexitstatus = exitstatus;
433	expredir(n->nredir.redirect);
434	if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
435			forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
436		if (backgnd)
437			flags &=~ EV_TESTED;
438		redirect(n->nredir.redirect, 0);
439		evaltree(n->nredir.n, flags | EV_EXIT);	/* never returns */
440	} else if (! backgnd) {
441		INTOFF;
442		exitstatus = waitforjob(jp, (int *)NULL);
443		INTON;
444	} else
445		exitstatus = 0;
446}
447
448
449/*
450 * Evaluate a redirected compound command.
451 */
452
453static void
454evalredir(union node *n, int flags)
455{
456	struct jmploc jmploc;
457	struct jmploc *savehandler;
458	volatile int in_redirect = 1;
459
460	oexitstatus = exitstatus;
461	expredir(n->nredir.redirect);
462	savehandler = handler;
463	if (setjmp(jmploc.loc)) {
464		int e;
465
466		handler = savehandler;
467		e = exception;
468		popredir();
469		if (e == EXERROR && in_redirect) {
470			FORCEINTON;
471			return;
472		}
473		longjmp(handler->loc, 1);
474	} else {
475		INTOFF;
476		handler = &jmploc;
477		redirect(n->nredir.redirect, REDIR_PUSH);
478		in_redirect = 0;
479		INTON;
480		evaltree(n->nredir.n, flags);
481	}
482	INTOFF;
483	handler = savehandler;
484	popredir();
485	INTON;
486}
487
488
489static void
490exphere(union node *redir, struct arglist *fn)
491{
492	struct jmploc jmploc;
493	struct jmploc *savehandler;
494	struct localvar *savelocalvars;
495	int need_longjmp = 0;
496	unsigned char saveoptreset;
497
498	redir->nhere.expdoc = "";
499	savelocalvars = localvars;
500	localvars = NULL;
501	saveoptreset = shellparam.reset;
502	forcelocal++;
503	savehandler = handler;
504	if (setjmp(jmploc.loc))
505		need_longjmp = exception != EXERROR;
506	else {
507		handler = &jmploc;
508		expandarg(redir->nhere.doc, fn, 0);
509		redir->nhere.expdoc = fn->args[0];
510		INTOFF;
511	}
512	handler = savehandler;
513	forcelocal--;
514	poplocalvars();
515	localvars = savelocalvars;
516	shellparam.reset = saveoptreset;
517	if (need_longjmp)
518		longjmp(handler->loc, 1);
519	INTON;
520}
521
522
523/*
524 * Compute the names of the files in a redirection list.
525 */
526
527static void
528expredir(union node *n)
529{
530	union node *redir;
531
532	for (redir = n ; redir ; redir = redir->nfile.next) {
533		struct arglist fn;
534		emptyarglist(&fn);
535		switch (redir->type) {
536		case NFROM:
537		case NTO:
538		case NFROMTO:
539		case NAPPEND:
540		case NCLOBBER:
541			expandarg(redir->nfile.fname, &fn, EXP_TILDE);
542			redir->nfile.expfname = fn.args[0];
543			break;
544		case NFROMFD:
545		case NTOFD:
546			if (redir->ndup.vname) {
547				expandarg(redir->ndup.vname, &fn, EXP_TILDE);
548				fixredir(redir, fn.args[0], 1);
549			}
550			break;
551		case NXHERE:
552			exphere(redir, &fn);
553			break;
554		}
555	}
556}
557
558
559
560/*
561 * Evaluate a pipeline.  All the processes in the pipeline are children
562 * of the process creating the pipeline.  (This differs from some versions
563 * of the shell, which make the last process in a pipeline the parent
564 * of all the rest.)
565 */
566
567static void
568evalpipe(union node *n)
569{
570	struct job *jp;
571	struct nodelist *lp;
572	int pipelen;
573	int prevfd;
574	int pip[2];
575
576	TRACE(("evalpipe(%p) called\n", (void *)n));
577	pipelen = 0;
578	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
579		pipelen++;
580	INTOFF;
581	jp = makejob(n, pipelen);
582	prevfd = -1;
583	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
584		prehash(lp->n);
585		pip[1] = -1;
586		if (lp->next) {
587			if (pipe(pip) < 0) {
588				if (prevfd >= 0)
589					close(prevfd);
590				error("Pipe call failed: %s", strerror(errno));
591			}
592		}
593		if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
594			INTON;
595			if (prevfd > 0) {
596				dup2(prevfd, 0);
597				close(prevfd);
598			}
599			if (pip[1] >= 0) {
600				if (!(prevfd >= 0 && pip[0] == 0))
601					close(pip[0]);
602				if (pip[1] != 1) {
603					dup2(pip[1], 1);
604					close(pip[1]);
605				}
606			}
607			evaltree(lp->n, EV_EXIT);
608		}
609		if (prevfd >= 0)
610			close(prevfd);
611		prevfd = pip[0];
612		if (pip[1] != -1)
613			close(pip[1]);
614	}
615	INTON;
616	if (n->npipe.backgnd == 0) {
617		INTOFF;
618		exitstatus = waitforjob(jp, (int *)NULL);
619		TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
620		INTON;
621	} else
622		exitstatus = 0;
623}
624
625
626
627static int
628is_valid_fast_cmdsubst(union node *n)
629{
630
631	return (n->type == NCMD);
632}
633
634/*
635 * Execute a command inside back quotes.  If it's a builtin command, we
636 * want to save its output in a block obtained from malloc.  Otherwise
637 * we fork off a subprocess and get the output of the command via a pipe.
638 * Should be called with interrupts off.
639 */
640
641void
642evalbackcmd(union node *n, struct backcmd *result)
643{
644	int pip[2];
645	struct job *jp;
646	struct stackmark smark;
647	struct jmploc jmploc;
648	struct jmploc *savehandler;
649	struct localvar *savelocalvars;
650	unsigned char saveoptreset;
651
652	result->fd = -1;
653	result->buf = NULL;
654	result->nleft = 0;
655	result->jp = NULL;
656	if (n == NULL) {
657		exitstatus = 0;
658		return;
659	}
660	setstackmark(&smark);
661	exitstatus = oexitstatus;
662	if (is_valid_fast_cmdsubst(n)) {
663		savelocalvars = localvars;
664		localvars = NULL;
665		saveoptreset = shellparam.reset;
666		forcelocal++;
667		savehandler = handler;
668		if (setjmp(jmploc.loc)) {
669			if (exception == EXERROR)
670				/* nothing */;
671			else if (exception != 0) {
672				handler = savehandler;
673				forcelocal--;
674				poplocalvars();
675				localvars = savelocalvars;
676				shellparam.reset = saveoptreset;
677				longjmp(handler->loc, 1);
678			}
679		} else {
680			handler = &jmploc;
681			evalcommand(n, EV_BACKCMD, result);
682		}
683		handler = savehandler;
684		forcelocal--;
685		poplocalvars();
686		localvars = savelocalvars;
687		shellparam.reset = saveoptreset;
688	} else {
689		if (pipe(pip) < 0)
690			error("Pipe call failed: %s", strerror(errno));
691		jp = makejob(n, 1);
692		if (forkshell(jp, n, FORK_NOJOB) == 0) {
693			FORCEINTON;
694			close(pip[0]);
695			if (pip[1] != 1) {
696				dup2(pip[1], 1);
697				close(pip[1]);
698			}
699			evaltree(n, EV_EXIT);
700		}
701		close(pip[1]);
702		result->fd = pip[0];
703		result->jp = jp;
704	}
705	popstackmark(&smark);
706	TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
707		result->fd, result->buf, result->nleft, result->jp));
708}
709
710static int
711mustexpandto(const char *argtext, const char *mask)
712{
713	for (;;) {
714		if (*argtext == CTLQUOTEMARK || *argtext == CTLQUOTEEND) {
715			argtext++;
716			continue;
717		}
718		if (*argtext == CTLESC)
719			argtext++;
720		else if (BASESYNTAX[(int)*argtext] == CCTL)
721			return (0);
722		if (*argtext != *mask)
723			return (0);
724		if (*argtext == '\0')
725			return (1);
726		argtext++;
727		mask++;
728	}
729}
730
731static int
732isdeclarationcmd(struct narg *arg)
733{
734	int have_command = 0;
735
736	if (arg == NULL)
737		return (0);
738	while (mustexpandto(arg->text, "command")) {
739		have_command = 1;
740		arg = &arg->next->narg;
741		if (arg == NULL)
742			return (0);
743		/*
744		 * To also allow "command -p" and "command --" as part of
745		 * a declaration command, add code here.
746		 * We do not do this, as ksh does not do it either and it
747		 * is not required by POSIX.
748		 */
749	}
750	return (mustexpandto(arg->text, "export") ||
751	    mustexpandto(arg->text, "readonly") ||
752	    (mustexpandto(arg->text, "local") &&
753		(have_command || !isfunc("local"))));
754}
755
756static void
757xtracecommand(struct arglist *varlist, int argc, char **argv)
758{
759	char sep = 0;
760	const char *text, *p, *ps4;
761	int i;
762
763	ps4 = expandstr(ps4val());
764	out2str(ps4 != NULL ? ps4 : ps4val());
765	for (i = 0; i < varlist->count; i++) {
766		text = varlist->args[i];
767		if (sep != 0)
768			out2c(' ');
769		p = strchr(text, '=');
770		if (p != NULL) {
771			p++;
772			outbin(text, p - text, out2);
773			out2qstr(p);
774		} else
775			out2qstr(text);
776		sep = ' ';
777	}
778	for (i = 0; i < argc; i++) {
779		text = argv[i];
780		if (sep != 0)
781			out2c(' ');
782		out2qstr(text);
783		sep = ' ';
784	}
785	out2c('\n');
786	flushout(&errout);
787}
788
789/*
790 * Check if a builtin can safely be executed in the same process,
791 * even though it should be in a subshell (command substitution).
792 * Note that jobid, jobs, times and trap can show information not
793 * available in a child process; this is deliberate.
794 * The arguments should already have been expanded.
795 */
796static int
797safe_builtin(int idx, int argc, char **argv)
798{
799	/* Generated from builtins.def. */
800	if (safe_builtin_always(idx))
801		return (1);
802	if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
803	    idx == UMASKCMD)
804		return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
805	if (idx == SETCMD)
806		return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
807		    argv[1][0] == '+') && argv[1][1] == 'o' &&
808		    argv[1][2] == '\0'));
809	return (0);
810}
811
812/*
813 * Execute a simple command.
814 * Note: This may or may not return if (flags & EV_EXIT).
815 */
816
817static void
818evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
819{
820	union node *argp;
821	struct arglist arglist;
822	struct arglist varlist;
823	char **argv;
824	int argc;
825	char **envp;
826	int varflag;
827	int mode;
828	int pip[2];
829	struct cmdentry cmdentry;
830	struct job *jp;
831	struct jmploc jmploc;
832	struct jmploc *savehandler;
833	char *savecmdname;
834	struct shparam saveparam;
835	struct localvar *savelocalvars;
836	struct parsefile *savetopfile;
837	volatile int e;
838	char *lastarg;
839	int signaled;
840	int do_clearcmdentry;
841	const char *path = pathval();
842	int i;
843
844	/* First expand the arguments. */
845	TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
846	emptyarglist(&arglist);
847	emptyarglist(&varlist);
848	varflag = 1;
849	jp = NULL;
850	do_clearcmdentry = 0;
851	oexitstatus = exitstatus;
852	exitstatus = 0;
853	/* Add one slot at the beginning for tryexec(). */
854	appendarglist(&arglist, nullstr);
855	for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
856		if (varflag && isassignment(argp->narg.text)) {
857			expandarg(argp, varflag == 1 ? &varlist : &arglist,
858			    EXP_VARTILDE);
859			continue;
860		} else if (varflag == 1)
861			varflag = isdeclarationcmd(&argp->narg) ? 2 : 0;
862		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
863	}
864	appendarglist(&arglist, nullstr);
865	expredir(cmd->ncmd.redirect);
866	argc = arglist.count - 2;
867	argv = &arglist.args[1];
868
869	argv[argc] = NULL;
870	lastarg = NULL;
871	if (iflag && funcnest == 0 && argc > 0)
872		lastarg = argv[argc - 1];
873
874	/* Print the command if xflag is set. */
875	if (xflag)
876		xtracecommand(&varlist, argc, argv);
877
878	/* Now locate the command. */
879	if (argc == 0) {
880		/* Variable assignment(s) without command */
881		cmdentry.cmdtype = CMDBUILTIN;
882		cmdentry.u.index = BLTINCMD;
883		cmdentry.special = 0;
884	} else {
885		static const char PATH[] = "PATH=";
886		int cmd_flags = 0, bltinonly = 0;
887
888		/*
889		 * Modify the command lookup path, if a PATH= assignment
890		 * is present
891		 */
892		for (i = 0; i < varlist.count; i++)
893			if (strncmp(varlist.args[i], PATH, sizeof(PATH) - 1) == 0) {
894				path = varlist.args[i] + sizeof(PATH) - 1;
895				/*
896				 * On `PATH=... command`, we need to make
897				 * sure that the command isn't using the
898				 * non-updated hash table of the outer PATH
899				 * setting and we need to make sure that
900				 * the hash table isn't filled with items
901				 * from the temporary setting.
902				 *
903				 * It would be better to forbit using and
904				 * updating the table while this command
905				 * runs, by the command finding mechanism
906				 * is heavily integrated with hash handling,
907				 * so we just delete the hash before and after
908				 * the command runs. Partly deleting like
909				 * changepatch() does doesn't seem worth the
910				 * bookinging effort, since most such runs add
911				 * directories in front of the new PATH.
912				 */
913				clearcmdentry();
914				do_clearcmdentry = 1;
915			}
916
917		for (;;) {
918			if (bltinonly) {
919				cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
920				if (cmdentry.u.index < 0) {
921					cmdentry.u.index = BLTINCMD;
922					argv--;
923					argc++;
924					break;
925				}
926			} else
927				find_command(argv[0], &cmdentry, cmd_flags, path);
928			/* implement the bltin and command builtins here */
929			if (cmdentry.cmdtype != CMDBUILTIN)
930				break;
931			if (cmdentry.u.index == BLTINCMD) {
932				if (argc == 1)
933					break;
934				argv++;
935				argc--;
936				bltinonly = 1;
937			} else if (cmdentry.u.index == COMMANDCMD) {
938				if (argc == 1)
939					break;
940				if (!strcmp(argv[1], "-p")) {
941					if (argc == 2)
942						break;
943					if (argv[2][0] == '-') {
944						if (strcmp(argv[2], "--"))
945							break;
946						if (argc == 3)
947							break;
948						argv += 3;
949						argc -= 3;
950					} else {
951						argv += 2;
952						argc -= 2;
953					}
954					path = _PATH_STDPATH;
955					clearcmdentry();
956					do_clearcmdentry = 1;
957				} else if (!strcmp(argv[1], "--")) {
958					if (argc == 2)
959						break;
960					argv += 2;
961					argc -= 2;
962				} else if (argv[1][0] == '-')
963					break;
964				else {
965					argv++;
966					argc--;
967				}
968				cmd_flags |= DO_NOFUNC;
969				bltinonly = 0;
970			} else
971				break;
972		}
973		/*
974		 * Special builtins lose their special properties when
975		 * called via 'command'.
976		 */
977		if (cmd_flags & DO_NOFUNC)
978			cmdentry.special = 0;
979	}
980
981	/* Fork off a child process if necessary. */
982	if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
983	    && ((flags & EV_EXIT) == 0 || have_traps()))
984	 || ((flags & EV_BACKCMD) != 0
985	    && (cmdentry.cmdtype != CMDBUILTIN ||
986		 !safe_builtin(cmdentry.u.index, argc, argv)))) {
987		jp = makejob(cmd, 1);
988		mode = FORK_FG;
989		if (flags & EV_BACKCMD) {
990			mode = FORK_NOJOB;
991			if (pipe(pip) < 0)
992				error("Pipe call failed: %s", strerror(errno));
993		}
994		if (cmdentry.cmdtype == CMDNORMAL &&
995		    cmd->ncmd.redirect == NULL &&
996		    varlist.count == 0 &&
997		    (mode == FORK_FG || mode == FORK_NOJOB) &&
998		    !disvforkset() && !iflag && !mflag) {
999			vforkexecshell(jp, argv, environment(), path,
1000			    cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL);
1001			goto parent;
1002		}
1003		if (forkshell(jp, cmd, mode) != 0)
1004			goto parent;	/* at end of routine */
1005		if (flags & EV_BACKCMD) {
1006			FORCEINTON;
1007			close(pip[0]);
1008			if (pip[1] != 1) {
1009				dup2(pip[1], 1);
1010				close(pip[1]);
1011			}
1012			flags &= ~EV_BACKCMD;
1013		}
1014		flags |= EV_EXIT;
1015	}
1016
1017	/* This is the child process if a fork occurred. */
1018	/* Execute the command. */
1019	if (cmdentry.cmdtype == CMDFUNCTION) {
1020#ifdef DEBUG
1021		trputs("Shell function:  ");  trargs(argv);
1022#endif
1023		saveparam = shellparam;
1024		shellparam.malloc = 0;
1025		shellparam.reset = 1;
1026		shellparam.nparam = argc - 1;
1027		shellparam.p = argv + 1;
1028		shellparam.optp = NULL;
1029		shellparam.optnext = NULL;
1030		INTOFF;
1031		savelocalvars = localvars;
1032		localvars = NULL;
1033		reffunc(cmdentry.u.func);
1034		savehandler = handler;
1035		if (setjmp(jmploc.loc)) {
1036			popredir();
1037			unreffunc(cmdentry.u.func);
1038			poplocalvars();
1039			localvars = savelocalvars;
1040			freeparam(&shellparam);
1041			shellparam = saveparam;
1042			funcnest--;
1043			handler = savehandler;
1044			longjmp(handler->loc, 1);
1045		}
1046		handler = &jmploc;
1047		funcnest++;
1048		redirect(cmd->ncmd.redirect, REDIR_PUSH);
1049		INTON;
1050		for (i = 0; i < varlist.count; i++)
1051			mklocal(varlist.args[i]);
1052		exitstatus = oexitstatus;
1053		evaltree(getfuncnode(cmdentry.u.func),
1054		    flags & (EV_TESTED | EV_EXIT));
1055		INTOFF;
1056		unreffunc(cmdentry.u.func);
1057		poplocalvars();
1058		localvars = savelocalvars;
1059		freeparam(&shellparam);
1060		shellparam = saveparam;
1061		handler = savehandler;
1062		funcnest--;
1063		popredir();
1064		INTON;
1065		if (evalskip == SKIPRETURN) {
1066			evalskip = 0;
1067			skipcount = 0;
1068		}
1069		if (jp)
1070			exitshell(exitstatus);
1071	} else if (cmdentry.cmdtype == CMDBUILTIN) {
1072#ifdef DEBUG
1073		trputs("builtin command:  ");  trargs(argv);
1074#endif
1075		mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
1076		if (flags == EV_BACKCMD) {
1077			memout.nextc = memout.buf;
1078			mode |= REDIR_BACKQ;
1079		}
1080		savecmdname = commandname;
1081		savetopfile = getcurrentfile();
1082		cmdenviron = &varlist;
1083		e = -1;
1084		savehandler = handler;
1085		if (setjmp(jmploc.loc)) {
1086			e = exception;
1087			if (e == EXINT)
1088				exitstatus = SIGINT+128;
1089			goto cmddone;
1090		}
1091		handler = &jmploc;
1092		redirect(cmd->ncmd.redirect, mode);
1093		outclearerror(out1);
1094		/*
1095		 * If there is no command word, redirection errors should
1096		 * not be fatal but assignment errors should.
1097		 */
1098		if (argc == 0)
1099			cmdentry.special = 1;
1100		listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1101		if (argc > 0)
1102			bltinsetlocale();
1103		commandname = argv[0];
1104		argptr = argv + 1;
1105		nextopt_optptr = NULL;		/* initialize nextopt */
1106		builtin_flags = flags;
1107		exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1108		flushall();
1109		if (outiserror(out1)) {
1110			warning("write error on stdout");
1111			if (exitstatus == 0 || exitstatus == 1)
1112				exitstatus = 2;
1113		}
1114cmddone:
1115		if (argc > 0)
1116			bltinunsetlocale();
1117		cmdenviron = NULL;
1118		out1 = &output;
1119		out2 = &errout;
1120		freestdout();
1121		handler = savehandler;
1122		commandname = savecmdname;
1123		if (jp)
1124			exitshell(exitstatus);
1125		if (flags == EV_BACKCMD) {
1126			backcmd->buf = memout.buf;
1127			backcmd->nleft = memout.buf != NULL ?
1128			    memout.nextc - memout.buf : 0;
1129			memout.buf = NULL;
1130			memout.nextc = NULL;
1131			memout.bufend = NULL;
1132			memout.bufsize = 64;
1133		}
1134		if (cmdentry.u.index != EXECCMD)
1135			popredir();
1136		if (e != -1) {
1137			if (e != EXERROR || cmdentry.special)
1138				exraise(e);
1139			popfilesupto(savetopfile);
1140			if (flags != EV_BACKCMD)
1141				FORCEINTON;
1142		}
1143	} else {
1144#ifdef DEBUG
1145		trputs("normal command:  ");  trargs(argv);
1146#endif
1147		redirect(cmd->ncmd.redirect, 0);
1148		for (i = 0; i < varlist.count; i++)
1149			setvareq(varlist.args[i], VEXPORT|VSTACK);
1150		envp = environment();
1151		shellexec(argv, envp, path, cmdentry.u.index);
1152		/*NOTREACHED*/
1153	}
1154	goto out;
1155
1156parent:	/* parent process gets here (if we forked) */
1157	if (mode == FORK_FG) {	/* argument to fork */
1158		INTOFF;
1159		exitstatus = waitforjob(jp, &signaled);
1160		INTON;
1161		if (iflag && loopnest > 0 && signaled) {
1162			evalskip = SKIPBREAK;
1163			skipcount = loopnest;
1164		}
1165	} else if (mode == FORK_NOJOB) {
1166		backcmd->fd = pip[0];
1167		close(pip[1]);
1168		backcmd->jp = jp;
1169	}
1170
1171out:
1172	if (lastarg)
1173		setvar("_", lastarg, 0);
1174	if (do_clearcmdentry)
1175		clearcmdentry();
1176}
1177
1178
1179
1180/*
1181 * Search for a command.  This is called before we fork so that the
1182 * location of the command will be available in the parent as well as
1183 * the child.  The check for "goodname" is an overly conservative
1184 * check that the name will not be subject to expansion.
1185 */
1186
1187static void
1188prehash(union node *n)
1189{
1190	struct cmdentry entry;
1191
1192	if (n && n->type == NCMD && n->ncmd.args)
1193		if (goodname(n->ncmd.args->narg.text))
1194			find_command(n->ncmd.args->narg.text, &entry, 0,
1195				     pathval());
1196}
1197
1198
1199
1200/*
1201 * Builtin commands.  Builtin commands whose functions are closely
1202 * tied to evaluation are implemented here.
1203 */
1204
1205/*
1206 * No command given, a bltin command with no arguments, or a bltin command
1207 * with an invalid name.
1208 */
1209
1210int
1211bltincmd(int argc, char **argv)
1212{
1213	if (argc > 1) {
1214		out2fmt_flush("%s: not found\n", argv[1]);
1215		return 127;
1216	}
1217	/*
1218	 * Preserve exitstatus of a previous possible command substitution
1219	 * as POSIX mandates
1220	 */
1221	return exitstatus;
1222}
1223
1224
1225/*
1226 * Handle break and continue commands.  Break, continue, and return are
1227 * all handled by setting the evalskip flag.  The evaluation routines
1228 * above all check this flag, and if it is set they start skipping
1229 * commands rather than executing them.  The variable skipcount is
1230 * the number of loops to break/continue, or the number of function
1231 * levels to return.  (The latter is always 1.)  It should probably
1232 * be an error to break out of more loops than exist, but it isn't
1233 * in the standard shell so we don't make it one here.
1234 */
1235
1236int
1237breakcmd(int argc, char **argv)
1238{
1239	long n;
1240	char *end;
1241
1242	if (argc > 1) {
1243		/* Allow arbitrarily large numbers. */
1244		n = strtol(argv[1], &end, 10);
1245		if (!is_digit(argv[1][0]) || *end != '\0')
1246			error("Illegal number: %s", argv[1]);
1247	} else
1248		n = 1;
1249	if (n > loopnest)
1250		n = loopnest;
1251	if (n > 0) {
1252		evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1253		skipcount = n;
1254	}
1255	return 0;
1256}
1257
1258/*
1259 * The `command' command.
1260 */
1261int
1262commandcmd(int argc __unused, char **argv __unused)
1263{
1264	const char *path;
1265	int ch;
1266	int cmd = -1;
1267
1268	path = bltinlookup("PATH", 1);
1269
1270	while ((ch = nextopt("pvV")) != '\0') {
1271		switch (ch) {
1272		case 'p':
1273			path = _PATH_STDPATH;
1274			break;
1275		case 'v':
1276			cmd = TYPECMD_SMALLV;
1277			break;
1278		case 'V':
1279			cmd = TYPECMD_BIGV;
1280			break;
1281		}
1282	}
1283
1284	if (cmd != -1) {
1285		if (*argptr == NULL || argptr[1] != NULL)
1286			error("wrong number of arguments");
1287		return typecmd_impl(2, argptr - 1, cmd, path);
1288	}
1289	if (*argptr != NULL)
1290		error("commandcmd bad call");
1291
1292	/*
1293	 * Do nothing successfully if no command was specified;
1294	 * ksh also does this.
1295	 */
1296	return 0;
1297}
1298
1299
1300/*
1301 * The return command.
1302 */
1303
1304int
1305returncmd(int argc, char **argv)
1306{
1307	int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1308
1309	evalskip = SKIPRETURN;
1310	skipcount = 1;
1311	return ret;
1312}
1313
1314
1315int
1316falsecmd(int argc __unused, char **argv __unused)
1317{
1318	return 1;
1319}
1320
1321
1322int
1323truecmd(int argc __unused, char **argv __unused)
1324{
1325	return 0;
1326}
1327
1328
1329int
1330execcmd(int argc, char **argv)
1331{
1332	int i;
1333
1334	/*
1335	 * Because we have historically not supported any options,
1336	 * only treat "--" specially.
1337	 */
1338	if (argc > 1 && strcmp(argv[1], "--") == 0)
1339		argc--, argv++;
1340	if (argc > 1) {
1341		iflag = 0;		/* exit on error */
1342		mflag = 0;
1343		optschanged();
1344		for (i = 0; i < cmdenviron->count; i++)
1345			setvareq(cmdenviron->args[i], VEXPORT|VSTACK);
1346		shellexec(argv + 1, environment(), pathval(), 0);
1347
1348	}
1349	return 0;
1350}
1351
1352
1353int
1354timescmd(int argc __unused, char **argv __unused)
1355{
1356	struct rusage ru;
1357	long shumins, shsmins, chumins, chsmins;
1358	double shusecs, shssecs, chusecs, chssecs;
1359
1360	if (getrusage(RUSAGE_SELF, &ru) < 0)
1361		return 1;
1362	shumins = ru.ru_utime.tv_sec / 60;
1363	shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1364	shsmins = ru.ru_stime.tv_sec / 60;
1365	shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1366	if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1367		return 1;
1368	chumins = ru.ru_utime.tv_sec / 60;
1369	chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1370	chsmins = ru.ru_stime.tv_sec / 60;
1371	chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1372	out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1373	    shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1374	return 0;
1375}
1376