1/*-
2 * Copyright (c) 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Kenneth Almquist.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#ifndef lint
34#if 0
35static char sccsid[] = "@(#)eval.c	8.9 (Berkeley) 6/8/95";
36#endif
37#endif /* not lint */
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD$");
40
41#include <paths.h>
42#include <signal.h>
43#include <stdlib.h>
44#include <unistd.h>
45#include <sys/resource.h>
46#include <sys/wait.h> /* For WIFSIGNALED(status) */
47#include <errno.h>
48
49/*
50 * Evaluate a command.
51 */
52
53#include "shell.h"
54#include "nodes.h"
55#include "syntax.h"
56#include "expand.h"
57#include "parser.h"
58#include "jobs.h"
59#include "eval.h"
60#include "builtins.h"
61#include "options.h"
62#include "exec.h"
63#include "redir.h"
64#include "input.h"
65#include "output.h"
66#include "trap.h"
67#include "var.h"
68#include "memalloc.h"
69#include "error.h"
70#include "show.h"
71#include "mystring.h"
72#ifndef NO_HISTORY
73#include "myhistedit.h"
74#endif
75
76
77int evalskip;			/* set if we are skipping commands */
78int skipcount;			/* number of levels to skip */
79static int loopnest;		/* current loop nesting level */
80int funcnest;			/* depth of function calls */
81static int builtin_flags;	/* evalcommand flags for builtins */
82
83
84char *commandname;
85struct strlist *cmdenviron;
86int exitstatus;			/* exit status of last command */
87int oexitstatus;		/* saved exit status */
88
89
90static void evalloop(union node *, int);
91static void evalfor(union node *, int);
92static union node *evalcase(union node *);
93static void evalsubshell(union node *, int);
94static void evalredir(union node *, int);
95static void exphere(union node *, struct arglist *);
96static void expredir(union node *);
97static void evalpipe(union node *);
98static int is_valid_fast_cmdsubst(union node *n);
99static void evalcommand(union node *, int, struct backcmd *);
100static void prehash(union node *);
101
102
103/*
104 * Called to reset things after an exception.
105 */
106
107void
108reseteval(void)
109{
110	evalskip = 0;
111	loopnest = 0;
112}
113
114
115/*
116 * The eval command.
117 */
118
119int
120evalcmd(int argc, char **argv)
121{
122        char *p;
123        char *concat;
124        char **ap;
125
126        if (argc > 1) {
127                p = argv[1];
128                if (argc > 2) {
129                        STARTSTACKSTR(concat);
130                        ap = argv + 2;
131                        for (;;) {
132                                STPUTS(p, concat);
133                                if ((p = *ap++) == NULL)
134                                        break;
135                                STPUTC(' ', concat);
136                        }
137                        STPUTC('\0', concat);
138                        p = grabstackstr(concat);
139                }
140                evalstring(p, builtin_flags);
141        } else
142                exitstatus = 0;
143        return exitstatus;
144}
145
146
147/*
148 * Execute a command or commands contained in a string.
149 */
150
151void
152evalstring(char *s, int flags)
153{
154	union node *n;
155	struct stackmark smark;
156	int flags_exit;
157	int any;
158
159	flags_exit = flags & EV_EXIT;
160	flags &= ~EV_EXIT;
161	any = 0;
162	setstackmark(&smark);
163	setinputstring(s, 1);
164	while ((n = parsecmd(0)) != NEOF) {
165		if (n != NULL && !nflag) {
166			if (flags_exit && preadateof())
167				evaltree(n, flags | EV_EXIT);
168			else
169				evaltree(n, flags);
170			any = 1;
171		}
172		popstackmark(&smark);
173		setstackmark(&smark);
174	}
175	popfile();
176	popstackmark(&smark);
177	if (!any)
178		exitstatus = 0;
179	if (flags_exit)
180		exraise(EXEXIT);
181}
182
183
184/*
185 * Evaluate a parse tree.  The value is left in the global variable
186 * exitstatus.
187 */
188
189void
190evaltree(union node *n, int flags)
191{
192	int do_etest;
193	union node *next;
194	struct stackmark smark;
195
196	setstackmark(&smark);
197	do_etest = 0;
198	if (n == NULL) {
199		TRACE(("evaltree(NULL) called\n"));
200		exitstatus = 0;
201		goto out;
202	}
203	do {
204		next = NULL;
205#ifndef NO_HISTORY
206		displayhist = 1;	/* show history substitutions done with fc */
207#endif
208		TRACE(("evaltree(%p: %d) called\n", (void *)n, n->type));
209		switch (n->type) {
210		case NSEMI:
211			evaltree(n->nbinary.ch1, flags & ~EV_EXIT);
212			if (evalskip)
213				goto out;
214			next = n->nbinary.ch2;
215			break;
216		case NAND:
217			evaltree(n->nbinary.ch1, EV_TESTED);
218			if (evalskip || exitstatus != 0) {
219				goto out;
220			}
221			next = n->nbinary.ch2;
222			break;
223		case NOR:
224			evaltree(n->nbinary.ch1, EV_TESTED);
225			if (evalskip || exitstatus == 0)
226				goto out;
227			next = n->nbinary.ch2;
228			break;
229		case NREDIR:
230			evalredir(n, flags);
231			break;
232		case NSUBSHELL:
233			evalsubshell(n, flags);
234			do_etest = !(flags & EV_TESTED);
235			break;
236		case NBACKGND:
237			evalsubshell(n, flags);
238			break;
239		case NIF: {
240			evaltree(n->nif.test, EV_TESTED);
241			if (evalskip)
242				goto out;
243			if (exitstatus == 0)
244				next = n->nif.ifpart;
245			else if (n->nif.elsepart)
246				next = n->nif.elsepart;
247			else
248				exitstatus = 0;
249			break;
250		}
251		case NWHILE:
252		case NUNTIL:
253			evalloop(n, flags & ~EV_EXIT);
254			break;
255		case NFOR:
256			evalfor(n, flags & ~EV_EXIT);
257			break;
258		case NCASE:
259			next = evalcase(n);
260			break;
261		case NCLIST:
262			next = n->nclist.body;
263			break;
264		case NCLISTFALLTHRU:
265			if (n->nclist.body) {
266				evaltree(n->nclist.body, flags & ~EV_EXIT);
267				if (evalskip)
268					goto out;
269			}
270			next = n->nclist.next;
271			break;
272		case NDEFUN:
273			defun(n->narg.text, n->narg.next);
274			exitstatus = 0;
275			break;
276		case NNOT:
277			evaltree(n->nnot.com, EV_TESTED);
278			if (evalskip)
279				goto out;
280			exitstatus = !exitstatus;
281			break;
282
283		case NPIPE:
284			evalpipe(n);
285			do_etest = !(flags & EV_TESTED);
286			break;
287		case NCMD:
288			evalcommand(n, flags, (struct backcmd *)NULL);
289			do_etest = !(flags & EV_TESTED);
290			break;
291		default:
292			out1fmt("Node type = %d\n", n->type);
293			flushout(&output);
294			break;
295		}
296		n = next;
297		popstackmark(&smark);
298		setstackmark(&smark);
299	} while (n != NULL);
300out:
301	popstackmark(&smark);
302	if (pendingsig)
303		dotrap();
304	if (eflag && exitstatus != 0 && do_etest)
305		exitshell(exitstatus);
306	if (flags & EV_EXIT)
307		exraise(EXEXIT);
308}
309
310
311static void
312evalloop(union node *n, int flags)
313{
314	int status;
315
316	loopnest++;
317	status = 0;
318	for (;;) {
319		evaltree(n->nbinary.ch1, EV_TESTED);
320		if (evalskip) {
321skipping:	  if (evalskip == SKIPCONT && --skipcount <= 0) {
322				evalskip = 0;
323				continue;
324			}
325			if (evalskip == SKIPBREAK && --skipcount <= 0)
326				evalskip = 0;
327			if (evalskip == SKIPRETURN)
328				status = exitstatus;
329			break;
330		}
331		if (n->type == NWHILE) {
332			if (exitstatus != 0)
333				break;
334		} else {
335			if (exitstatus == 0)
336				break;
337		}
338		evaltree(n->nbinary.ch2, flags);
339		status = exitstatus;
340		if (evalskip)
341			goto skipping;
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	struct strlist *sp;
355	int status;
356
357	arglist.lastp = &arglist.list;
358	for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
359		oexitstatus = exitstatus;
360		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
361	}
362	*arglist.lastp = NULL;
363
364	loopnest++;
365	status = 0;
366	for (sp = arglist.list ; sp ; sp = sp->next) {
367		setvar(n->nfor.var, sp->text, 0);
368		evaltree(n->nfor.body, flags);
369		status = exitstatus;
370		if (evalskip) {
371			if (evalskip == SKIPCONT && --skipcount <= 0) {
372				evalskip = 0;
373				continue;
374			}
375			if (evalskip == SKIPBREAK && --skipcount <= 0)
376				evalskip = 0;
377			break;
378		}
379	}
380	loopnest--;
381	exitstatus = status;
382}
383
384
385/*
386 * Evaluate a case statement, returning the selected tree.
387 *
388 * The exit status needs care to get right.
389 */
390
391static union node *
392evalcase(union node *n)
393{
394	union node *cp;
395	union node *patp;
396	struct arglist arglist;
397
398	arglist.lastp = &arglist.list;
399	oexitstatus = exitstatus;
400	expandarg(n->ncase.expr, &arglist, EXP_TILDE);
401	for (cp = n->ncase.cases ; cp ; cp = cp->nclist.next) {
402		for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
403			if (casematch(patp, arglist.list->text)) {
404				while (cp->nclist.next &&
405				    cp->type == NCLISTFALLTHRU &&
406				    cp->nclist.body == NULL)
407					cp = cp->nclist.next;
408				if (cp->nclist.next &&
409				    cp->type == NCLISTFALLTHRU)
410					return (cp);
411				if (cp->nclist.body == NULL)
412					exitstatus = 0;
413				return (cp->nclist.body);
414			}
415		}
416	}
417	exitstatus = 0;
418	return (NULL);
419}
420
421
422
423/*
424 * Kick off a subshell to evaluate a tree.
425 */
426
427static void
428evalsubshell(union node *n, int flags)
429{
430	struct job *jp;
431	int backgnd = (n->type == NBACKGND);
432
433	oexitstatus = exitstatus;
434	expredir(n->nredir.redirect);
435	if ((!backgnd && flags & EV_EXIT && !have_traps()) ||
436			forkshell(jp = makejob(n, 1), n, backgnd) == 0) {
437		if (backgnd)
438			flags &=~ EV_TESTED;
439		redirect(n->nredir.redirect, 0);
440		evaltree(n->nredir.n, flags | EV_EXIT);	/* never returns */
441	} else if (! backgnd) {
442		INTOFF;
443		exitstatus = waitforjob(jp, (int *)NULL);
444		INTON;
445	} else
446		exitstatus = 0;
447}
448
449
450/*
451 * Evaluate a redirected compound command.
452 */
453
454static void
455evalredir(union node *n, int flags)
456{
457	struct jmploc jmploc;
458	struct jmploc *savehandler;
459	volatile int in_redirect = 1;
460
461	oexitstatus = exitstatus;
462	expredir(n->nredir.redirect);
463	savehandler = handler;
464	if (setjmp(jmploc.loc)) {
465		int e;
466
467		handler = savehandler;
468		e = exception;
469		popredir();
470		if (e == EXERROR || e == EXEXEC) {
471			if (in_redirect) {
472				exitstatus = 2;
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
500	redir->nhere.expdoc = nullstr;
501	savelocalvars = localvars;
502	localvars = NULL;
503	forcelocal++;
504	savehandler = handler;
505	if (setjmp(jmploc.loc))
506		need_longjmp = exception != EXERROR && exception != EXEXEC;
507	else {
508		handler = &jmploc;
509		expandarg(redir->nhere.doc, fn, 0);
510		redir->nhere.expdoc = fn->list->text;
511		INTOFF;
512	}
513	handler = savehandler;
514	forcelocal--;
515	poplocalvars();
516	localvars = savelocalvars;
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		fn.lastp = &fn.list;
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 | EXP_REDIR);
542			redir->nfile.expfname = fn.list->text;
543			break;
544		case NFROMFD:
545		case NTOFD:
546			if (redir->ndup.vname) {
547				expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
548				fixredir(redir, fn.list->text, 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
651	setstackmark(&smark);
652	result->fd = -1;
653	result->buf = NULL;
654	result->nleft = 0;
655	result->jp = NULL;
656	if (n == NULL) {
657		exitstatus = 0;
658		goto out;
659	}
660	exitstatus = oexitstatus;
661	if (is_valid_fast_cmdsubst(n)) {
662		savelocalvars = localvars;
663		localvars = NULL;
664		forcelocal++;
665		savehandler = handler;
666		if (setjmp(jmploc.loc)) {
667			if (exception == EXERROR || exception == EXEXEC)
668				exitstatus = 2;
669			else if (exception != 0) {
670				handler = savehandler;
671				forcelocal--;
672				poplocalvars();
673				localvars = savelocalvars;
674				longjmp(handler->loc, 1);
675			}
676		} else {
677			handler = &jmploc;
678			evalcommand(n, EV_BACKCMD, result);
679		}
680		handler = savehandler;
681		forcelocal--;
682		poplocalvars();
683		localvars = savelocalvars;
684	} else {
685		if (pipe(pip) < 0)
686			error("Pipe call failed: %s", strerror(errno));
687		jp = makejob(n, 1);
688		if (forkshell(jp, n, FORK_NOJOB) == 0) {
689			FORCEINTON;
690			close(pip[0]);
691			if (pip[1] != 1) {
692				dup2(pip[1], 1);
693				close(pip[1]);
694			}
695			evaltree(n, EV_EXIT);
696		}
697		close(pip[1]);
698		result->fd = pip[0];
699		result->jp = jp;
700	}
701out:
702	popstackmark(&smark);
703	TRACE(("evalbackcmd done: fd=%d buf=%p nleft=%d jp=%p\n",
704		result->fd, result->buf, result->nleft, result->jp));
705}
706
707static int
708mustexpandto(const char *argtext, const char *mask)
709{
710	for (;;) {
711		if (*argtext == CTLQUOTEMARK || *argtext == CTLQUOTEEND) {
712			argtext++;
713			continue;
714		}
715		if (*argtext == CTLESC)
716			argtext++;
717		else if (BASESYNTAX[(int)*argtext] == CCTL)
718			return (0);
719		if (*argtext != *mask)
720			return (0);
721		if (*argtext == '\0')
722			return (1);
723		argtext++;
724		mask++;
725	}
726}
727
728static int
729isdeclarationcmd(struct narg *arg)
730{
731	int have_command = 0;
732
733	if (arg == NULL)
734		return (0);
735	while (mustexpandto(arg->text, "command")) {
736		have_command = 1;
737		arg = &arg->next->narg;
738		if (arg == NULL)
739			return (0);
740		/*
741		 * To also allow "command -p" and "command --" as part of
742		 * a declaration command, add code here.
743		 * We do not do this, as ksh does not do it either and it
744		 * is not required by POSIX.
745		 */
746	}
747	return (mustexpandto(arg->text, "export") ||
748	    mustexpandto(arg->text, "readonly") ||
749	    (mustexpandto(arg->text, "local") &&
750		(have_command || !isfunc("local"))));
751}
752
753/*
754 * Check if a builtin can safely be executed in the same process,
755 * even though it should be in a subshell (command substitution).
756 * Note that jobid, jobs, times and trap can show information not
757 * available in a child process; this is deliberate.
758 * The arguments should already have been expanded.
759 */
760static int
761safe_builtin(int idx, int argc, char **argv)
762{
763	if (idx == BLTINCMD || idx == COMMANDCMD || idx == ECHOCMD ||
764	    idx == FALSECMD || idx == JOBIDCMD || idx == JOBSCMD ||
765	    idx == KILLCMD || idx == PRINTFCMD || idx == PWDCMD ||
766	    idx == TESTCMD || idx == TIMESCMD || idx == TRUECMD ||
767	    idx == TYPECMD)
768		return (1);
769	if (idx == EXPORTCMD || idx == TRAPCMD || idx == ULIMITCMD ||
770	    idx == UMASKCMD)
771		return (argc <= 1 || (argc == 2 && argv[1][0] == '-'));
772	if (idx == SETCMD)
773		return (argc <= 1 || (argc == 2 && (argv[1][0] == '-' ||
774		    argv[1][0] == '+') && argv[1][1] == 'o' &&
775		    argv[1][2] == '\0'));
776	return (0);
777}
778
779/*
780 * Execute a simple command.
781 * Note: This may or may not return if (flags & EV_EXIT).
782 */
783
784static void
785evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
786{
787	union node *argp;
788	struct arglist arglist;
789	struct arglist varlist;
790	char **argv;
791	int argc;
792	char **envp;
793	int varflag;
794	struct strlist *sp;
795	int mode;
796	int pip[2];
797	struct cmdentry cmdentry;
798	struct job *jp;
799	struct jmploc jmploc;
800	struct jmploc *savehandler;
801	char *savecmdname;
802	struct shparam saveparam;
803	struct localvar *savelocalvars;
804	struct parsefile *savetopfile;
805	volatile int e;
806	char *lastarg;
807	int realstatus;
808	int do_clearcmdentry;
809	const char *path = pathval();
810
811	/* First expand the arguments. */
812	TRACE(("evalcommand(%p, %d) called\n", (void *)cmd, flags));
813	arglist.lastp = &arglist.list;
814	varlist.lastp = &varlist.list;
815	varflag = 1;
816	jp = NULL;
817	do_clearcmdentry = 0;
818	oexitstatus = exitstatus;
819	exitstatus = 0;
820	for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
821		if (varflag && isassignment(argp->narg.text)) {
822			expandarg(argp, varflag == 1 ? &varlist : &arglist,
823			    EXP_VARTILDE);
824			continue;
825		} else if (varflag == 1)
826			varflag = isdeclarationcmd(&argp->narg) ? 2 : 0;
827		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
828	}
829	*arglist.lastp = NULL;
830	*varlist.lastp = NULL;
831	expredir(cmd->ncmd.redirect);
832	argc = 0;
833	for (sp = arglist.list ; sp ; sp = sp->next)
834		argc++;
835	/* Add one slot at the beginning for tryexec(). */
836	argv = stalloc(sizeof (char *) * (argc + 2));
837	argv++;
838
839	for (sp = arglist.list ; sp ; sp = sp->next) {
840		TRACE(("evalcommand arg: %s\n", sp->text));
841		*argv++ = sp->text;
842	}
843	*argv = NULL;
844	lastarg = NULL;
845	if (iflag && funcnest == 0 && argc > 0)
846		lastarg = argv[-1];
847	argv -= argc;
848
849	/* Print the command if xflag is set. */
850	if (xflag) {
851		char sep = 0;
852		const char *p, *ps4;
853		ps4 = expandstr(ps4val());
854		out2str(ps4 != NULL ? ps4 : ps4val());
855		for (sp = varlist.list ; sp ; sp = sp->next) {
856			if (sep != 0)
857				out2c(' ');
858			p = strchr(sp->text, '=');
859			if (p != NULL) {
860				p++;
861				outbin(sp->text, p - sp->text, out2);
862				out2qstr(p);
863			} else
864				out2qstr(sp->text);
865			sep = ' ';
866		}
867		for (sp = arglist.list ; sp ; sp = sp->next) {
868			if (sep != 0)
869				out2c(' ');
870			/* Disambiguate command looking like assignment. */
871			if (sp == arglist.list &&
872					strchr(sp->text, '=') != NULL &&
873					strchr(sp->text, '\'') == NULL) {
874				out2c('\'');
875				out2str(sp->text);
876				out2c('\'');
877			} else
878				out2qstr(sp->text);
879			sep = ' ';
880		}
881		out2c('\n');
882		flushout(&errout);
883	}
884
885	/* Now locate the command. */
886	if (argc == 0) {
887		/* Variable assignment(s) without command */
888		cmdentry.cmdtype = CMDBUILTIN;
889		cmdentry.u.index = BLTINCMD;
890		cmdentry.special = 0;
891	} else {
892		static const char PATH[] = "PATH=";
893		int cmd_flags = 0, bltinonly = 0;
894
895		/*
896		 * Modify the command lookup path, if a PATH= assignment
897		 * is present
898		 */
899		for (sp = varlist.list ; sp ; sp = sp->next)
900			if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0) {
901				path = sp->text + sizeof(PATH) - 1;
902				/*
903				 * On `PATH=... command`, we need to make
904				 * sure that the command isn't using the
905				 * non-updated hash table of the outer PATH
906				 * setting and we need to make sure that
907				 * the hash table isn't filled with items
908				 * from the temporary setting.
909				 *
910				 * It would be better to forbit using and
911				 * updating the table while this command
912				 * runs, by the command finding mechanism
913				 * is heavily integrated with hash handling,
914				 * so we just delete the hash before and after
915				 * the command runs. Partly deleting like
916				 * changepatch() does doesn't seem worth the
917				 * bookinging effort, since most such runs add
918				 * directories in front of the new PATH.
919				 */
920				clearcmdentry();
921				do_clearcmdentry = 1;
922			}
923
924		for (;;) {
925			if (bltinonly) {
926				cmdentry.u.index = find_builtin(*argv, &cmdentry.special);
927				if (cmdentry.u.index < 0) {
928					cmdentry.u.index = BLTINCMD;
929					argv--;
930					argc++;
931					break;
932				}
933			} else
934				find_command(argv[0], &cmdentry, cmd_flags, path);
935			/* implement the bltin and command builtins here */
936			if (cmdentry.cmdtype != CMDBUILTIN)
937				break;
938			if (cmdentry.u.index == BLTINCMD) {
939				if (argc == 1)
940					break;
941				argv++;
942				argc--;
943				bltinonly = 1;
944			} else if (cmdentry.u.index == COMMANDCMD) {
945				if (argc == 1)
946					break;
947				if (!strcmp(argv[1], "-p")) {
948					if (argc == 2)
949						break;
950					if (argv[2][0] == '-') {
951						if (strcmp(argv[2], "--"))
952							break;
953						if (argc == 3)
954							break;
955						argv += 3;
956						argc -= 3;
957					} else {
958						argv += 2;
959						argc -= 2;
960					}
961					path = _PATH_STDPATH;
962					clearcmdentry();
963					do_clearcmdentry = 1;
964				} else if (!strcmp(argv[1], "--")) {
965					if (argc == 2)
966						break;
967					argv += 2;
968					argc -= 2;
969				} else if (argv[1][0] == '-')
970					break;
971				else {
972					argv++;
973					argc--;
974				}
975				cmd_flags |= DO_NOFUNC;
976				bltinonly = 0;
977			} else
978				break;
979		}
980		/*
981		 * Special builtins lose their special properties when
982		 * called via 'command'.
983		 */
984		if (cmd_flags & DO_NOFUNC)
985			cmdentry.special = 0;
986	}
987
988	/* Fork off a child process if necessary. */
989	if (((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
990	    && ((flags & EV_EXIT) == 0 || have_traps()))
991	 || ((flags & EV_BACKCMD) != 0
992	    && (cmdentry.cmdtype != CMDBUILTIN ||
993		 !safe_builtin(cmdentry.u.index, argc, argv)))) {
994		jp = makejob(cmd, 1);
995		mode = FORK_FG;
996		if (flags & EV_BACKCMD) {
997			mode = FORK_NOJOB;
998			if (pipe(pip) < 0)
999				error("Pipe call failed: %s", strerror(errno));
1000		}
1001		if (cmdentry.cmdtype == CMDNORMAL &&
1002		    cmd->ncmd.redirect == NULL &&
1003		    varlist.list == NULL &&
1004		    (mode == FORK_FG || mode == FORK_NOJOB) &&
1005		    !disvforkset() && !iflag && !mflag) {
1006			vforkexecshell(jp, argv, environment(), path,
1007			    cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL);
1008			goto parent;
1009		}
1010		if (forkshell(jp, cmd, mode) != 0)
1011			goto parent;	/* at end of routine */
1012		if (flags & EV_BACKCMD) {
1013			FORCEINTON;
1014			close(pip[0]);
1015			if (pip[1] != 1) {
1016				dup2(pip[1], 1);
1017				close(pip[1]);
1018			}
1019			flags &= ~EV_BACKCMD;
1020		}
1021		flags |= EV_EXIT;
1022	}
1023
1024	/* This is the child process if a fork occurred. */
1025	/* Execute the command. */
1026	if (cmdentry.cmdtype == CMDFUNCTION) {
1027#ifdef DEBUG
1028		trputs("Shell function:  ");  trargs(argv);
1029#endif
1030		saveparam = shellparam;
1031		shellparam.malloc = 0;
1032		shellparam.reset = 1;
1033		shellparam.nparam = argc - 1;
1034		shellparam.p = argv + 1;
1035		shellparam.optnext = NULL;
1036		INTOFF;
1037		savelocalvars = localvars;
1038		localvars = NULL;
1039		reffunc(cmdentry.u.func);
1040		savehandler = handler;
1041		if (setjmp(jmploc.loc)) {
1042			freeparam(&shellparam);
1043			shellparam = saveparam;
1044			popredir();
1045			unreffunc(cmdentry.u.func);
1046			poplocalvars();
1047			localvars = savelocalvars;
1048			funcnest--;
1049			handler = savehandler;
1050			longjmp(handler->loc, 1);
1051		}
1052		handler = &jmploc;
1053		funcnest++;
1054		redirect(cmd->ncmd.redirect, REDIR_PUSH);
1055		INTON;
1056		for (sp = varlist.list ; sp ; sp = sp->next)
1057			mklocal(sp->text);
1058		exitstatus = oexitstatus;
1059		evaltree(getfuncnode(cmdentry.u.func),
1060		    flags & (EV_TESTED | EV_EXIT));
1061		INTOFF;
1062		unreffunc(cmdentry.u.func);
1063		poplocalvars();
1064		localvars = savelocalvars;
1065		freeparam(&shellparam);
1066		shellparam = saveparam;
1067		handler = savehandler;
1068		funcnest--;
1069		popredir();
1070		INTON;
1071		if (evalskip == SKIPRETURN) {
1072			evalskip = 0;
1073			skipcount = 0;
1074		}
1075		if (jp)
1076			exitshell(exitstatus);
1077	} else if (cmdentry.cmdtype == CMDBUILTIN) {
1078#ifdef DEBUG
1079		trputs("builtin command:  ");  trargs(argv);
1080#endif
1081		mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
1082		if (flags == EV_BACKCMD) {
1083			memout.nleft = 0;
1084			memout.nextc = memout.buf;
1085			memout.bufsize = 64;
1086			mode |= REDIR_BACKQ;
1087		}
1088		savecmdname = commandname;
1089		savetopfile = getcurrentfile();
1090		cmdenviron = varlist.list;
1091		e = -1;
1092		savehandler = handler;
1093		if (setjmp(jmploc.loc)) {
1094			e = exception;
1095			if (e == EXINT)
1096				exitstatus = SIGINT+128;
1097			else if (e != EXEXIT)
1098				exitstatus = 2;
1099			goto cmddone;
1100		}
1101		handler = &jmploc;
1102		redirect(cmd->ncmd.redirect, mode);
1103		outclearerror(out1);
1104		/*
1105		 * If there is no command word, redirection errors should
1106		 * not be fatal but assignment errors should.
1107		 */
1108		if (argc == 0)
1109			cmdentry.special = 1;
1110		listsetvar(cmdenviron, cmdentry.special ? 0 : VNOSET);
1111		if (argc > 0)
1112			bltinsetlocale();
1113		commandname = argv[0];
1114		argptr = argv + 1;
1115		nextopt_optptr = NULL;		/* initialize nextopt */
1116		builtin_flags = flags;
1117		exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
1118		flushall();
1119		if (outiserror(out1)) {
1120			warning("write error on stdout");
1121			if (exitstatus == 0 || exitstatus == 1)
1122				exitstatus = 2;
1123		}
1124cmddone:
1125		if (argc > 0)
1126			bltinunsetlocale();
1127		cmdenviron = NULL;
1128		out1 = &output;
1129		out2 = &errout;
1130		freestdout();
1131		handler = savehandler;
1132		commandname = savecmdname;
1133		if (jp)
1134			exitshell(exitstatus);
1135		if (flags == EV_BACKCMD) {
1136			backcmd->buf = memout.buf;
1137			backcmd->nleft = memout.nextc - memout.buf;
1138			memout.buf = NULL;
1139		}
1140		if (cmdentry.u.index != EXECCMD)
1141			popredir();
1142		if (e != -1) {
1143			if ((e != EXERROR && e != EXEXEC)
1144			    || cmdentry.special)
1145				exraise(e);
1146			popfilesupto(savetopfile);
1147			if (flags != EV_BACKCMD)
1148				FORCEINTON;
1149		}
1150	} else {
1151#ifdef DEBUG
1152		trputs("normal command:  ");  trargs(argv);
1153#endif
1154		redirect(cmd->ncmd.redirect, 0);
1155		for (sp = varlist.list ; sp ; sp = sp->next)
1156			setvareq(sp->text, VEXPORT|VSTACK);
1157		envp = environment();
1158		shellexec(argv, envp, path, cmdentry.u.index);
1159		/*NOTREACHED*/
1160	}
1161	goto out;
1162
1163parent:	/* parent process gets here (if we forked) */
1164	if (mode == FORK_FG) {	/* argument to fork */
1165		INTOFF;
1166		exitstatus = waitforjob(jp, &realstatus);
1167		INTON;
1168		if (iflag && loopnest > 0 && WIFSIGNALED(realstatus)) {
1169			evalskip = SKIPBREAK;
1170			skipcount = loopnest;
1171		}
1172	} else if (mode == FORK_NOJOB) {
1173		backcmd->fd = pip[0];
1174		close(pip[1]);
1175		backcmd->jp = jp;
1176	}
1177
1178out:
1179	if (lastarg)
1180		setvar("_", lastarg, 0);
1181	if (do_clearcmdentry)
1182		clearcmdentry();
1183}
1184
1185
1186
1187/*
1188 * Search for a command.  This is called before we fork so that the
1189 * location of the command will be available in the parent as well as
1190 * the child.  The check for "goodname" is an overly conservative
1191 * check that the name will not be subject to expansion.
1192 */
1193
1194static void
1195prehash(union node *n)
1196{
1197	struct cmdentry entry;
1198
1199	if (n && n->type == NCMD && n->ncmd.args)
1200		if (goodname(n->ncmd.args->narg.text))
1201			find_command(n->ncmd.args->narg.text, &entry, 0,
1202				     pathval());
1203}
1204
1205
1206
1207/*
1208 * Builtin commands.  Builtin commands whose functions are closely
1209 * tied to evaluation are implemented here.
1210 */
1211
1212/*
1213 * No command given, a bltin command with no arguments, or a bltin command
1214 * with an invalid name.
1215 */
1216
1217int
1218bltincmd(int argc, char **argv)
1219{
1220	if (argc > 1) {
1221		out2fmt_flush("%s: not found\n", argv[1]);
1222		return 127;
1223	}
1224	/*
1225	 * Preserve exitstatus of a previous possible redirection
1226	 * as POSIX mandates
1227	 */
1228	return exitstatus;
1229}
1230
1231
1232/*
1233 * Handle break and continue commands.  Break, continue, and return are
1234 * all handled by setting the evalskip flag.  The evaluation routines
1235 * above all check this flag, and if it is set they start skipping
1236 * commands rather than executing them.  The variable skipcount is
1237 * the number of loops to break/continue, or the number of function
1238 * levels to return.  (The latter is always 1.)  It should probably
1239 * be an error to break out of more loops than exist, but it isn't
1240 * in the standard shell so we don't make it one here.
1241 */
1242
1243int
1244breakcmd(int argc, char **argv)
1245{
1246	int n = argc > 1 ? number(argv[1]) : 1;
1247
1248	if (n > loopnest)
1249		n = loopnest;
1250	if (n > 0) {
1251		evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1252		skipcount = n;
1253	}
1254	return 0;
1255}
1256
1257/*
1258 * The `command' command.
1259 */
1260int
1261commandcmd(int argc __unused, char **argv __unused)
1262{
1263	const char *path;
1264	int ch;
1265	int cmd = -1;
1266
1267	path = bltinlookup("PATH", 1);
1268
1269	while ((ch = nextopt("pvV")) != '\0') {
1270		switch (ch) {
1271		case 'p':
1272			path = _PATH_STDPATH;
1273			break;
1274		case 'v':
1275			cmd = TYPECMD_SMALLV;
1276			break;
1277		case 'V':
1278			cmd = TYPECMD_BIGV;
1279			break;
1280		}
1281	}
1282
1283	if (cmd != -1) {
1284		if (*argptr == NULL || argptr[1] != NULL)
1285			error("wrong number of arguments");
1286		return typecmd_impl(2, argptr - 1, cmd, path);
1287	}
1288	if (*argptr != NULL)
1289		error("commandcmd bad call");
1290
1291	/*
1292	 * Do nothing successfully if no command was specified;
1293	 * ksh also does this.
1294	 */
1295	return 0;
1296}
1297
1298
1299/*
1300 * The return command.
1301 */
1302
1303int
1304returncmd(int argc, char **argv)
1305{
1306	int ret = argc > 1 ? number(argv[1]) : oexitstatus;
1307
1308	evalskip = SKIPRETURN;
1309	skipcount = 1;
1310	return ret;
1311}
1312
1313
1314int
1315falsecmd(int argc __unused, char **argv __unused)
1316{
1317	return 1;
1318}
1319
1320
1321int
1322truecmd(int argc __unused, char **argv __unused)
1323{
1324	return 0;
1325}
1326
1327
1328int
1329execcmd(int argc, char **argv)
1330{
1331	/*
1332	 * Because we have historically not supported any options,
1333	 * only treat "--" specially.
1334	 */
1335	if (argc > 1 && strcmp(argv[1], "--") == 0)
1336		argc--, argv++;
1337	if (argc > 1) {
1338		struct strlist *sp;
1339
1340		iflag = 0;		/* exit on error */
1341		mflag = 0;
1342		optschanged();
1343		for (sp = cmdenviron; sp ; sp = sp->next)
1344			setvareq(sp->text, VEXPORT|VSTACK);
1345		shellexec(argv + 1, environment(), pathval(), 0);
1346
1347	}
1348	return 0;
1349}
1350
1351
1352int
1353timescmd(int argc __unused, char **argv __unused)
1354{
1355	struct rusage ru;
1356	long shumins, shsmins, chumins, chsmins;
1357	double shusecs, shssecs, chusecs, chssecs;
1358
1359	if (getrusage(RUSAGE_SELF, &ru) < 0)
1360		return 1;
1361	shumins = ru.ru_utime.tv_sec / 60;
1362	shusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1363	shsmins = ru.ru_stime.tv_sec / 60;
1364	shssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1365	if (getrusage(RUSAGE_CHILDREN, &ru) < 0)
1366		return 1;
1367	chumins = ru.ru_utime.tv_sec / 60;
1368	chusecs = ru.ru_utime.tv_sec % 60 + ru.ru_utime.tv_usec / 1000000.;
1369	chsmins = ru.ru_stime.tv_sec / 60;
1370	chssecs = ru.ru_stime.tv_sec % 60 + ru.ru_stime.tv_usec / 1000000.;
1371	out1fmt("%ldm%.3fs %ldm%.3fs\n%ldm%.3fs %ldm%.3fs\n", shumins,
1372	    shusecs, shsmins, shssecs, chumins, chusecs, chsmins, chssecs);
1373	return 0;
1374}
1375