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 || e == EXEXEC) {
470			if (in_redirect) {
471				exitstatus = 2;
472				FORCEINTON;
473				return;
474			}
475		}
476		longjmp(handler->loc, 1);
477	} else {
478		INTOFF;
479		handler = &jmploc;
480		redirect(n->nredir.redirect, REDIR_PUSH);
481		in_redirect = 0;
482		INTON;
483		evaltree(n->nredir.n, flags);
484	}
485	INTOFF;
486	handler = savehandler;
487	popredir();
488	INTON;
489}
490
491
492static void
493exphere(union node *redir, struct arglist *fn)
494{
495	struct jmploc jmploc;
496	struct jmploc *savehandler;
497	struct localvar *savelocalvars;
498	int need_longjmp = 0;
499	unsigned char saveoptreset;
500
501	redir->nhere.expdoc = "";
502	savelocalvars = localvars;
503	localvars = NULL;
504	saveoptreset = shellparam.reset;
505	forcelocal++;
506	savehandler = handler;
507	if (setjmp(jmploc.loc))
508		need_longjmp = exception != EXERROR && exception != EXEXEC;
509	else {
510		handler = &jmploc;
511		expandarg(redir->nhere.doc, fn, 0);
512		redir->nhere.expdoc = fn->args[0];
513		INTOFF;
514	}
515	handler = savehandler;
516	forcelocal--;
517	poplocalvars();
518	localvars = savelocalvars;
519	shellparam.reset = saveoptreset;
520	if (need_longjmp)
521		longjmp(handler->loc, 1);
522	INTON;
523}
524
525
526/*
527 * Compute the names of the files in a redirection list.
528 */
529
530static void
531expredir(union node *n)
532{
533	union node *redir;
534
535	for (redir = n ; redir ; redir = redir->nfile.next) {
536		struct arglist fn;
537		emptyarglist(&fn);
538		switch (redir->type) {
539		case NFROM:
540		case NTO:
541		case NFROMTO:
542		case NAPPEND:
543		case NCLOBBER:
544			expandarg(redir->nfile.fname, &fn, EXP_TILDE);
545			redir->nfile.expfname = fn.args[0];
546			break;
547		case NFROMFD:
548		case NTOFD:
549			if (redir->ndup.vname) {
550				expandarg(redir->ndup.vname, &fn, EXP_TILDE);
551				fixredir(redir, fn.args[0], 1);
552			}
553			break;
554		case NXHERE:
555			exphere(redir, &fn);
556			break;
557		}
558	}
559}
560
561
562
563/*
564 * Evaluate a pipeline.  All the processes in the pipeline are children
565 * of the process creating the pipeline.  (This differs from some versions
566 * of the shell, which make the last process in a pipeline the parent
567 * of all the rest.)
568 */
569
570static void
571evalpipe(union node *n)
572{
573	struct job *jp;
574	struct nodelist *lp;
575	int pipelen;
576	int prevfd;
577	int pip[2];
578
579	TRACE(("evalpipe(%p) called\n", (void *)n));
580	pipelen = 0;
581	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
582		pipelen++;
583	INTOFF;
584	jp = makejob(n, pipelen);
585	prevfd = -1;
586	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
587		prehash(lp->n);
588		pip[1] = -1;
589		if (lp->next) {
590			if (pipe(pip) < 0) {
591				if (prevfd >= 0)
592					close(prevfd);
593				error("Pipe call failed: %s", strerror(errno));
594			}
595		}
596		if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
597			INTON;
598			if (prevfd > 0) {
599				dup2(prevfd, 0);
600				close(prevfd);
601			}
602			if (pip[1] >= 0) {
603				if (!(prevfd >= 0 && pip[0] == 0))
604					close(pip[0]);
605				if (pip[1] != 1) {
606					dup2(pip[1], 1);
607					close(pip[1]);
608				}
609			}
610			evaltree(lp->n, EV_EXIT);
611		}
612		if (prevfd >= 0)
613			close(prevfd);
614		prevfd = pip[0];
615		if (pip[1] != -1)
616			close(pip[1]);
617	}
618	INTON;
619	if (n->npipe.backgnd == 0) {
620		INTOFF;
621		exitstatus = waitforjob(jp, (int *)NULL);
622		TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
623		INTON;
624	} else
625		exitstatus = 0;
626}
627
628
629
630static int
631is_valid_fast_cmdsubst(union node *n)
632{
633
634	return (n->type == NCMD);
635}
636
637/*
638 * Execute a command inside back quotes.  If it's a builtin command, we
639 * want to save its output in a block obtained from malloc.  Otherwise
640 * we fork off a subprocess and get the output of the command via a pipe.
641 * Should be called with interrupts off.
642 */
643
644void
645evalbackcmd(union node *n, struct backcmd *result)
646{
647	int pip[2];
648	struct job *jp;
649	struct stackmark smark;
650	struct jmploc jmploc;
651	struct jmploc *savehandler;
652	struct localvar *savelocalvars;
653	unsigned char saveoptreset;
654
655	result->fd = -1;
656	result->buf = NULL;
657	result->nleft = 0;
658	result->jp = NULL;
659	if (n == NULL) {
660		exitstatus = 0;
661		return;
662	}
663	setstackmark(&smark);
664	exitstatus = oexitstatus;
665	if (is_valid_fast_cmdsubst(n)) {
666		savelocalvars = localvars;
667		localvars = NULL;
668		saveoptreset = shellparam.reset;
669		forcelocal++;
670		savehandler = handler;
671		if (setjmp(jmploc.loc)) {
672			if (exception == EXERROR || exception == EXEXEC)
673				exitstatus = 2;
674			else if (exception != 0) {
675				handler = savehandler;
676				forcelocal--;
677				poplocalvars();
678				localvars = savelocalvars;
679				shellparam.reset = saveoptreset;
680				longjmp(handler->loc, 1);
681			}
682		} else {
683			handler = &jmploc;
684			evalcommand(n, EV_BACKCMD, result);
685		}
686		handler = savehandler;
687		forcelocal--;
688		poplocalvars();
689		localvars = savelocalvars;
690		shellparam.reset = saveoptreset;
691	} else {
692		if (pipe(pip) < 0)
693			error("Pipe call failed: %s", strerror(errno));
694		jp = makejob(n, 1);
695		if (forkshell(jp, n, FORK_NOJOB) == 0) {
696			FORCEINTON;
697			close(pip[0]);
698			if (pip[1] != 1) {
699				dup2(pip[1], 1);
700				close(pip[1]);
701			}
702			evaltree(n, EV_EXIT);
703		}
704		close(pip[1]);
705		result->fd = pip[0];
706		result->jp = jp;
707	}
708	popstackmark(&smark);
709	TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
710		result->fd, result->buf, result->nleft, result->jp));
711}
712
713static int
714mustexpandto(const char *argtext, const char *mask)
715{
716	for (;;) {
717		if (*argtext == CTLQUOTEMARK || *argtext == CTLQUOTEEND) {
718			argtext++;
719			continue;
720		}
721		if (*argtext == CTLESC)
722			argtext++;
723		else if (BASESYNTAX[(int)*argtext] == CCTL)
724			return (0);
725		if (*argtext != *mask)
726			return (0);
727		if (*argtext == '\0')
728			return (1);
729		argtext++;
730		mask++;
731	}
732}
733
734static int
735isdeclarationcmd(struct narg *arg)
736{
737	int have_command = 0;
738
739	if (arg == NULL)
740		return (0);
741	while (mustexpandto(arg->text, "command")) {
742		have_command = 1;
743		arg = &arg->next->narg;
744		if (arg == NULL)
745			return (0);
746		/*
747		 * To also allow "command -p" and "command --" as part of
748		 * a declaration command, add code here.
749		 * We do not do this, as ksh does not do it either and it
750		 * is not required by POSIX.
751		 */
752	}
753	return (mustexpandto(arg->text, "export") ||
754	    mustexpandto(arg->text, "readonly") ||
755	    (mustexpandto(arg->text, "local") &&
756		(have_command || !isfunc("local"))));
757}
758
759static void
760xtracecommand(struct arglist *varlist, int argc, char **argv)
761{
762	char sep = 0;
763	const char *text, *p, *ps4;
764	int i;
765
766	ps4 = expandstr(ps4val());
767	out2str(ps4 != NULL ? ps4 : ps4val());
768	for (i = 0; i < varlist->count; i++) {
769		text = varlist->args[i];
770		if (sep != 0)
771			out2c(' ');
772		p = strchr(text, '=');
773		if (p != NULL) {
774			p++;
775			outbin(text, p - text, out2);
776			out2qstr(p);
777		} else
778			out2qstr(text);
779		sep = ' ';
780	}
781	for (i = 0; i < argc; i++) {
782		text = argv[i];
783		if (sep != 0)
784			out2c(' ');
785		out2qstr(text);
786		sep = ' ';
787	}
788	out2c('\n');
789	flushout(&errout);
790}
791
792/*
793 * Check if a builtin can safely be executed in the same process,
794 * even though it should be in a subshell (command substitution).
795 * Note that jobid, jobs, times and trap can show information not
796 * available in a child process; this is deliberate.
797 * The arguments should already have been expanded.
798 */
799static int
800safe_builtin(int idx, int argc, char **argv)
801{
802	/* Generated from builtins.def. */
803	if (safe_builtin_always(idx))
804		return (1);
805	if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
806	    idx == UMASKCMD)
807		return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
808	if (idx == SETCMD)
809		return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
810		    argv[1][0] == '+') && argv[1][1] == 'o' &&
811		    argv[1][2] == '\0'));
812	return (0);
813}
814
815/*
816 * Execute a simple command.
817 * Note: This may or may not return if (flags & EV_EXIT).
818 */
819
820static void
821evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
822{
823	union node *argp;
824	struct arglist arglist;
825	struct arglist varlist;
826	char **argv;
827	int argc;
828	char **envp;
829	int varflag;
830	int mode;
831	int pip[2];
832	struct cmdentry cmdentry;
833	struct job *jp;
834	struct jmploc jmploc;
835	struct jmploc *savehandler;
836	char *savecmdname;
837	struct shparam saveparam;
838	struct localvar *savelocalvars;
839	struct parsefile *savetopfile;
840	volatile int e;
841	char *lastarg;
842	int signaled;
843	int do_clearcmdentry;
844	const char *path = pathval();
845	int i;
846
847	/* First expand the arguments. */
848	TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
849	emptyarglist(&arglist);
850	emptyarglist(&varlist);
851	varflag = 1;
852	jp = NULL;
853	do_clearcmdentry = 0;
854	oexitstatus = exitstatus;
855	exitstatus = 0;
856	/* Add one slot at the beginning for tryexec(). */
857	appendarglist(&arglist, nullstr);
858	for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
859		if (varflag && isassignment(argp->narg.text)) {
860			expandarg(argp, varflag == 1 ? &varlist : &arglist,
861			    EXP_VARTILDE);
862			continue;
863		} else if (varflag == 1)
864			varflag = isdeclarationcmd(&argp->narg) ? 2 : 0;
865		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
866	}
867	appendarglist(&arglist, nullstr);
868	expredir(cmd->ncmd.redirect);
869	argc = arglist.count - 2;
870	argv = &arglist.args[1];
871
872	argv[argc] = NULL;
873	lastarg = NULL;
874	if (iflag && funcnest == 0 && argc > 0)
875		lastarg = argv[argc - 1];
876
877	/* Print the command if xflag is set. */
878	if (xflag)
879		xtracecommand(&varlist, argc, argv);
880
881	/* Now locate the command. */
882	if (argc == 0) {
883		/* Variable assignment(s) without command */
884		cmdentry.cmdtype = CMDBUILTIN;
885		cmdentry.u.index = BLTINCMD;
886		cmdentry.special = 0;
887	} else {
888		static const char PATH[] = "PATH=";
889		int cmd_flags = 0, bltinonly = 0;
890
891		/*
892		 * Modify the command lookup path, if a PATH= assignment
893		 * is present
894		 */
895		for (i = 0; i < varlist.count; i++)
896			if (strncmp(varlist.args[i], PATH, sizeof(PATH) - 1) == 0) {
897				path = varlist.args[i] + sizeof(PATH) - 1;
898				/*
899				 * On `PATH=... command`, we need to make
900				 * sure that the command isn't using the
901				 * non-updated hash table of the outer PATH
902				 * setting and we need to make sure that
903				 * the hash table isn't filled with items
904				 * from the temporary setting.
905				 *
906				 * It would be better to forbit using and
907				 * updating the table while this command
908				 * runs, by the command finding mechanism
909				 * is heavily integrated with hash handling,
910				 * so we just delete the hash before and after
911				 * the command runs. Partly deleting like
912				 * changepatch() does doesn't seem worth the
913				 * bookinging effort, since most such runs add
914				 * directories in front of the new PATH.
915				 */
916				clearcmdentry();
917				do_clearcmdentry = 1;
918			}
919
920		for (;;) {
921			if (bltinonly) {
922				cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
923				if (cmdentry.u.index < 0) {
924					cmdentry.u.index = BLTINCMD;
925					argv--;
926					argc++;
927					break;
928				}
929			} else
930				find_command(argv[0], &cmdentry, cmd_flags, path);
931			/* implement the bltin and command builtins here */
932			if (cmdentry.cmdtype != CMDBUILTIN)
933				break;
934			if (cmdentry.u.index == BLTINCMD) {
935				if (argc == 1)
936					break;
937				argv++;
938				argc--;
939				bltinonly = 1;
940			} else if (cmdentry.u.index == COMMANDCMD) {
941				if (argc == 1)
942					break;
943				if (!strcmp(argv[1], "-p")) {
944					if (argc == 2)
945						break;
946					if (argv[2][0] == '-') {
947						if (strcmp(argv[2], "--"))
948							break;
949						if (argc == 3)
950							break;
951						argv += 3;
952						argc -= 3;
953					} else {
954						argv += 2;
955						argc -= 2;
956					}
957					path = _PATH_STDPATH;
958					clearcmdentry();
959					do_clearcmdentry = 1;
960				} else if (!strcmp(argv[1], "--")) {
961					if (argc == 2)
962						break;
963					argv += 2;
964					argc -= 2;
965				} else if (argv[1][0] == '-')
966					break;
967				else {
968					argv++;
969					argc--;
970				}
971				cmd_flags |= DO_NOFUNC;
972				bltinonly = 0;
973			} else
974				break;
975		}
976		/*
977		 * Special builtins lose their special properties when
978		 * called via 'command'.
979		 */
980		if (cmd_flags & DO_NOFUNC)
981			cmdentry.special = 0;
982	}
983
984	/* Fork off a child process if necessary. */
985	if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
986	    && ((flags & EV_EXIT) == 0 || have_traps()))
987	 || ((flags & EV_BACKCMD) != 0
988	    && (cmdentry.cmdtype != CMDBUILTIN ||
989		 !safe_builtin(cmdentry.u.index, argc, argv)))) {
990		jp = makejob(cmd, 1);
991		mode = FORK_FG;
992		if (flags & EV_BACKCMD) {
993			mode = FORK_NOJOB;
994			if (pipe(pip) < 0)
995				error("Pipe call failed: %s", strerror(errno));
996		}
997		if (cmdentry.cmdtype == CMDNORMAL &&
998		    cmd->ncmd.redirect == NULL &&
999		    varlist.count == 0 &&
1000		    (mode == FORK_FG || mode == FORK_NOJOB) &&
1001		    !disvforkset() && !iflag && !mflag) {
1002			vforkexecshell(jp, argv, environment(), path,
1003			    cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL);
1004			goto parent;
1005		}
1006		if (forkshell(jp, cmd, mode) != 0)
1007			goto parent;	/* at end of routine */
1008		if (flags & EV_BACKCMD) {
1009			FORCEINTON;
1010			close(pip[0]);
1011			if (pip[1] != 1) {
1012				dup2(pip[1], 1);
1013				close(pip[1]);
1014			}
1015			flags &= ~EV_BACKCMD;
1016		}
1017		flags |= EV_EXIT;
1018	}
1019
1020	/* This is the child process if a fork occurred. */
1021	/* Execute the command. */
1022	if (cmdentry.cmdtype == CMDFUNCTION) {
1023#ifdef DEBUG
1024		trputs("Shell function:  ");  trargs(argv);
1025#endif
1026		saveparam = shellparam;
1027		shellparam.malloc = 0;
1028		shellparam.reset = 1;
1029		shellparam.nparam = argc - 1;
1030		shellparam.p = argv + 1;
1031		shellparam.optp = NULL;
1032		shellparam.optnext = NULL;
1033		INTOFF;
1034		savelocalvars = localvars;
1035		localvars = NULL;
1036		reffunc(cmdentry.u.func);
1037		savehandler = handler;
1038		if (setjmp(jmploc.loc)) {
1039			popredir();
1040			unreffunc(cmdentry.u.func);
1041			poplocalvars();
1042			localvars = savelocalvars;
1043			freeparam(&shellparam);
1044			shellparam = saveparam;
1045			funcnest--;
1046			handler = savehandler;
1047			longjmp(handler->loc, 1);
1048		}
1049		handler = &jmploc;
1050		funcnest++;
1051		redirect(cmd->ncmd.redirect, REDIR_PUSH);
1052		INTON;
1053		for (i = 0; i < varlist.count; i++)
1054			mklocal(varlist.args[i]);
1055		exitstatus = oexitstatus;
1056		evaltree(getfuncnode(cmdentry.u.func),
1057		    flags & (EV_TESTED | EV_EXIT));
1058		INTOFF;
1059		unreffunc(cmdentry.u.func);
1060		poplocalvars();
1061		localvars = savelocalvars;
1062		freeparam(&shellparam);
1063		shellparam = saveparam;
1064		handler = savehandler;
1065		funcnest--;
1066		popredir();
1067		INTON;
1068		if (evalskip == SKIPRETURN) {
1069			evalskip = 0;
1070			skipcount = 0;
1071		}
1072		if (jp)
1073			exitshell(exitstatus);
1074	} else if (cmdentry.cmdtype == CMDBUILTIN) {
1075#ifdef DEBUG
1076		trputs("builtin command:  ");  trargs(argv);
1077#endif
1078		mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
1079		if (flags == EV_BACKCMD) {
1080			memout.nextc = memout.buf;
1081			mode |= REDIR_BACKQ;
1082		}
1083		savecmdname = commandname;
1084		savetopfile = getcurrentfile();
1085		cmdenviron = &varlist;
1086		e = -1;
1087		savehandler = handler;
1088		if (setjmp(jmploc.loc)) {
1089			e = exception;
1090			if (e == EXINT)
1091				exitstatus = SIGINT+128;
1092			else if (e != EXEXIT)
1093				exitstatus = 2;
1094			goto cmddone;
1095		}
1096		handler = &jmploc;
1097		redirect(cmd->ncmd.redirect, mode);
1098		outclearerror(out1);
1099		/*
1100		 * If there is no command word, redirection errors should
1101		 * not be fatal but assignment errors should.
1102		 */
1103		if (argc == 0)
1104			cmdentry.special = 1;
1105		listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1106		if (argc > 0)
1107			bltinsetlocale();
1108		commandname = argv[0];
1109		argptr = argv + 1;
1110		nextopt_optptr = NULL;		/* initialize nextopt */
1111		builtin_flags = flags;
1112		exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1113		flushall();
1114		if (outiserror(out1)) {
1115			warning("write error on stdout");
1116			if (exitstatus == 0 || exitstatus == 1)
1117				exitstatus = 2;
1118		}
1119cmddone:
1120		if (argc > 0)
1121			bltinunsetlocale();
1122		cmdenviron = NULL;
1123		out1 = &output;
1124		out2 = &errout;
1125		freestdout();
1126		handler = savehandler;
1127		commandname = savecmdname;
1128		if (jp)
1129			exitshell(exitstatus);
1130		if (flags == EV_BACKCMD) {
1131			backcmd->buf = memout.buf;
1132			backcmd->nleft = memout.buf != NULL ?
1133			    memout.nextc - memout.buf : 0;
1134			memout.buf = NULL;
1135			memout.nextc = NULL;
1136			memout.bufend = NULL;
1137			memout.bufsize = 64;
1138		}
1139		if (cmdentry.u.index != EXECCMD)
1140			popredir();
1141		if (e != -1) {
1142			if ((e != EXERROR && e != EXEXEC)
1143			    || cmdentry.special)
1144				exraise(e);
1145			popfilesupto(savetopfile);
1146			if (flags != EV_BACKCMD)
1147				FORCEINTON;
1148		}
1149	} else {
1150#ifdef DEBUG
1151		trputs("normal command:  ");  trargs(argv);
1152#endif
1153		redirect(cmd->ncmd.redirect, 0);
1154		for (i = 0; i < varlist.count; i++)
1155			setvareq(varlist.args[i], VEXPORT|VSTACK);
1156		envp = environment();
1157		shellexec(argv, envp, path, cmdentry.u.index);
1158		/*NOTREACHED*/
1159	}
1160	goto out;
1161
1162parent:	/* parent process gets here (if we forked) */
1163	if (mode == FORK_FG) {	/* argument to fork */
1164		INTOFF;
1165		exitstatus = waitforjob(jp, &signaled);
1166		INTON;
1167		if (iflag && loopnest > 0 && signaled) {
1168			evalskip = SKIPBREAK;
1169			skipcount = loopnest;
1170		}
1171	} else if (mode == FORK_NOJOB) {
1172		backcmd->fd = pip[0];
1173		close(pip[1]);
1174		backcmd->jp = jp;
1175	}
1176
1177out:
1178	if (lastarg)
1179		setvar("_", lastarg, 0);
1180	if (do_clearcmdentry)
1181		clearcmdentry();
1182}
1183
1184
1185
1186/*
1187 * Search for a command.  This is called before we fork so that the
1188 * location of the command will be available in the parent as well as
1189 * the child.  The check for "goodname" is an overly conservative
1190 * check that the name will not be subject to expansion.
1191 */
1192
1193static void
1194prehash(union node *n)
1195{
1196	struct cmdentry entry;
1197
1198	if (n && n->type == NCMD && n->ncmd.args)
1199		if (goodname(n->ncmd.args->narg.text))
1200			find_command(n->ncmd.args->narg.text, &entry, 0,
1201				     pathval());
1202}
1203
1204
1205
1206/*
1207 * Builtin commands.  Builtin commands whose functions are closely
1208 * tied to evaluation are implemented here.
1209 */
1210
1211/*
1212 * No command given, a bltin command with no arguments, or a bltin command
1213 * with an invalid name.
1214 */
1215
1216int
1217bltincmd(int argc, char **argv)
1218{
1219	if (argc > 1) {
1220		out2fmt_flush("%s: not found\n", argv[1]);
1221		return 127;
1222	}
1223	/*
1224	 * Preserve exitstatus of a previous possible command substitution
1225	 * as POSIX mandates
1226	 */
1227	return exitstatus;
1228}
1229
1230
1231/*
1232 * Handle break and continue commands.  Break, continue, and return are
1233 * all handled by setting the evalskip flag.  The evaluation routines
1234 * above all check this flag, and if it is set they start skipping
1235 * commands rather than executing them.  The variable skipcount is
1236 * the number of loops to break/continue, or the number of function
1237 * levels to return.  (The latter is always 1.)  It should probably
1238 * be an error to break out of more loops than exist, but it isn't
1239 * in the standard shell so we don't make it one here.
1240 */
1241
1242int
1243breakcmd(int argc, char **argv)
1244{
1245	long n;
1246	char *end;
1247
1248	if (argc > 1) {
1249		/* Allow arbitrarily large numbers. */
1250		n = strtol(argv[1], &end, 10);
1251		if (!is_digit(argv[1][0]) || *end != '\0')
1252			error("Illegal number: %s", argv[1]);
1253	} else
1254		n = 1;
1255	if (n > loopnest)
1256		n = loopnest;
1257	if (n > 0) {
1258		evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1259		skipcount = n;
1260	}
1261	return 0;
1262}
1263
1264/*
1265 * The `command' command.
1266 */
1267int
1268commandcmd(int argc __unused, char **argv __unused)
1269{
1270	const char *path;
1271	int ch;
1272	int cmd = -1;
1273
1274	path = bltinlookup("PATH", 1);
1275
1276	while ((ch = nextopt("pvV")) != '\0') {
1277		switch (ch) {
1278		case 'p':
1279			path = _PATH_STDPATH;
1280			break;
1281		case 'v':
1282			cmd = TYPECMD_SMALLV;
1283			break;
1284		case 'V':
1285			cmd = TYPECMD_BIGV;
1286			break;
1287		}
1288	}
1289
1290	if (cmd != -1) {
1291		if (*argptr == NULL || argptr[1] != NULL)
1292			error("wrong number of arguments");
1293		return typecmd_impl(2, argptr - 1, cmd, path);
1294	}
1295	if (*argptr != NULL)
1296		error("commandcmd bad call");
1297
1298	/*
1299	 * Do nothing successfully if no command was specified;
1300	 * ksh also does this.
1301	 */
1302	return 0;
1303}
1304
1305
1306/*
1307 * The return command.
1308 */
1309
1310int
1311returncmd(int argc, char **argv)
1312{
1313	int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1314
1315	evalskip = SKIPRETURN;
1316	skipcount = 1;
1317	return ret;
1318}
1319
1320
1321int
1322falsecmd(int argc __unused, char **argv __unused)
1323{
1324	return 1;
1325}
1326
1327
1328int
1329truecmd(int argc __unused, char **argv __unused)
1330{
1331	return 0;
1332}
1333
1334
1335int
1336execcmd(int argc, char **argv)
1337{
1338	int i;
1339
1340	/*
1341	 * Because we have historically not supported any options,
1342	 * only treat "--" specially.
1343	 */
1344	if (argc > 1 && strcmp(argv[1], "--") == 0)
1345		argc--, argv++;
1346	if (argc > 1) {
1347		iflag = 0;		/* exit on error */
1348		mflag = 0;
1349		optschanged();
1350		for (i = 0; i < cmdenviron->count; i++)
1351			setvareq(cmdenviron->args[i], VEXPORT|VSTACK);
1352		shellexec(argv + 1, environment(), pathval(), 0);
1353
1354	}
1355	return 0;
1356}
1357
1358
1359int
1360timescmd(int argc __unused, char **argv __unused)
1361{
1362	struct rusage ru;
1363	long shumins, shsmins, chumins, chsmins;
1364	double shusecs, shssecs, chusecs, chssecs;
1365
1366	if (getrusage(RUSAGE_SELF, &ru) < 0)
1367		return 1;
1368	shumins = ru.ru_utime.tv_sec / 60;
1369	shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1370	shsmins = ru.ru_stime.tv_sec / 60;
1371	shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1372	if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1373		return 1;
1374	chumins = ru.ru_utime.tv_sec / 60;
1375	chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1376	chsmins = ru.ru_stime.tv_sec / 60;
1377	chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1378	out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1379	    shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1380	return 0;
1381}
1382