summary refs log tree commit diff
path: root/src/eval.c
blob: 77291b406747e462ddc72abd1411b6b37b77891d (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
/*-
 * Copyright (c) 1993
 *	The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1997-2005
 *	Herbert Xu <herbert@gondor.apana.org.au>.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
#include <sys/types.h>

/*
 * Evaluate a command.
 */

#include "shell.h"
#include "nodes.h"
#include "syntax.h"
#include "expand.h"
#include "parser.h"
#include "jobs.h"
#include "eval.h"
#include "builtins.h"
#include "options.h"
#include "exec.h"
#include "redir.h"
#include "input.h"
#include "output.h"
#include "trap.h"
#include "var.h"
#include "memalloc.h"
#include "error.h"
#include "show.h"
#include "mystring.h"
#ifndef SMALL
#include "myhistedit.h"
#endif


/* flags in argument to evaltree */
#define EV_EXIT 01		/* exit after evaluating tree */
#define EV_TESTED 02		/* exit status is checked; ignore -e flag */
#define EV_BACKCMD 04		/* command executing within back quotes */

int evalskip;			/* set if we are skipping commands */
STATIC int skipcount;		/* number of levels to skip */
MKINIT int loopnest;		/* current loop nesting level */
static int funcnest;		/* depth of function calls */


char *commandname;
struct strlist *cmdenviron;
int exitstatus;			/* exit status of last command */
int back_exitstatus;		/* exit status of backquoted command */


#if !defined(__alpha__) || (defined(__GNUC__) && __GNUC__ >= 3)
STATIC
#endif
void evaltreenr(union node *, int) __attribute__ ((__noreturn__));
STATIC void evalloop(union node *, int);
STATIC void evalfor(union node *, int);
STATIC void evalcase(union node *, int);
STATIC void evalsubshell(union node *, int);
STATIC void expredir(union node *);
STATIC void evalpipe(union node *, int);
#ifdef notyet
STATIC void evalcommand(union node *, int, struct backcmd *);
#else
STATIC void evalcommand(union node *, int);
#endif
STATIC int evalbltin(const struct builtincmd *, int, char **);
STATIC int evalfun(struct funcnode *, int, char **, int);
STATIC void prehash(union node *);
STATIC int eprintlist(struct output *, struct strlist *, int);
STATIC int bltincmd(int, char **);


STATIC const struct builtincmd bltin = {
	name: nullstr,
	builtin: bltincmd
};


/*
 * Called to reset things after an exception.
 */

#ifdef mkinit
INCLUDE "eval.h"

RESET {
	evalskip = 0;
	loopnest = 0;
}
#endif



/*
 * The eval commmand.
 */

int
evalcmd(int argc, char **argv)
{
        char *p;
        char *concat;
        char **ap;

        if (argc > 1) {
                p = argv[1];
                if (argc > 2) {
                        STARTSTACKSTR(concat);
                        ap = argv + 2;
                        for (;;) {
                        	concat = stputs(p, concat);
                                if ((p = *ap++) == NULL)
                                        break;
                                STPUTC(' ', concat);
                        }
                        STPUTC('\0', concat);
                        p = grabstackstr(concat);
                }
                return evalstring(p, ~SKIPEVAL);
        }
        return 0;
}


/*
 * Execute a command or commands contained in a string.
 */

int
evalstring(char *s, int mask)
{
	union node *n;
	struct stackmark smark;
	int status;

	setinputstring(s);
	setstackmark(&smark);

	status = 0;
	while ((n = parsecmd(0)) != NEOF) {
		evaltree(n, 0);
		status = exitstatus;
		popstackmark(&smark);
		if (evalskip)
			break;
	}
	popfile();

	evalskip &= mask;
	return status;
}



/*
 * Evaluate a parse tree.  The value is left in the global variable
 * exitstatus.
 */

void
evaltree(union node *n, int flags)
{
	int checkexit = 0;
	void (*evalfn)(union node *, int);
	unsigned isor;
	int status;
	if (n == NULL) {
		TRACE(("evaltree(NULL) called\n"));
		goto out;
	}
#ifndef SMALL
	displayhist = 1;	/* show history substitutions done with fc */
#endif
	TRACE(("pid %d, evaltree(%p: %d, %d) called\n",
	    getpid(), n, n->type, flags));
	switch (n->type) {
	default:
#ifdef DEBUG
		out1fmt("Node type = %d\n", n->type);
#ifndef USE_GLIBC_STDIO
		flushout(out1);
#endif
		break;
#endif
	case NNOT:
		evaltree(n->nnot.com, EV_TESTED);
		status = !exitstatus;
		goto setstatus;
	case NREDIR:
		expredir(n->nredir.redirect);
		status = redirectsafe(n->nredir.redirect, REDIR_PUSH);
		if (!status) {
			evaltree(n->nredir.n, flags & EV_TESTED);
			status = exitstatus;
		}
		popredir(0);
		goto setstatus;
	case NCMD:
#ifdef notyet
		if (eflag && !(flags & EV_TESTED))
			checkexit = ~0;
		evalcommand(n, flags, (struct backcmd *)NULL);
		break;
#else
		evalfn = evalcommand;
checkexit:
		if (eflag && !(flags & EV_TESTED))
			checkexit = ~0;
		goto calleval;
#endif
	case NFOR:
		evalfn = evalfor;
		goto calleval;
	case NWHILE:
	case NUNTIL:
		evalfn = evalloop;
		goto calleval;
	case NSUBSHELL:
	case NBACKGND:
		evalfn = evalsubshell;
		goto calleval;
	case NPIPE:
		evalfn = evalpipe;
#ifdef notyet
		if (eflag && !(flags & EV_TESTED))
			checkexit = ~0;
		goto calleval;
#else
		goto checkexit;
#endif
	case NCASE:
		evalfn = evalcase;
		goto calleval;
	case NAND:
	case NOR:
	case NSEMI:
#if NAND + 1 != NOR
#error NAND + 1 != NOR
#endif
#if NOR + 1 != NSEMI
#error NOR + 1 != NSEMI
#endif
		isor = n->type - NAND;
		evaltree(
			n->nbinary.ch1,
			(flags | ((isor >> 1) - 1)) & EV_TESTED
		);
		if (!exitstatus == isor)
			break;
		if (!evalskip) {
			n = n->nbinary.ch2;
evaln:
			evalfn = evaltree;
calleval:
			evalfn(n, flags);
			break;
		}
		break;
	case NIF:
		evaltree(n->nif.test, EV_TESTED);
		if (evalskip)
			break;
		if (exitstatus == 0) {
			n = n->nif.ifpart;
			goto evaln;
		} else if (n->nif.elsepart) {
			n = n->nif.elsepart;
			goto evaln;
		}
		goto success;
	case NDEFUN:
		defun(n->narg.text, n->narg.next);
success:
		status = 0;
setstatus:
		exitstatus = status;
		break;
	}
out:
	if ((checkexit & exitstatus))
		evalskip |= SKIPEVAL;
	else if (pendingsigs && dotrap())
		goto exexit;

	if (flags & EV_EXIT) {
exexit:
		exraise(EXEXIT);
	}
}


#if !defined(__alpha__) || (defined(__GNUC__) && __GNUC__ >= 3)
STATIC
#endif
void evaltreenr(union node *, int) __attribute__ ((alias("evaltree")));


STATIC void
evalloop(union node *n, int flags)
{
	int status;

	loopnest++;
	status = 0;
	flags &= EV_TESTED;
	for (;;) {
		int i;

		evaltree(n->nbinary.ch1, EV_TESTED);
		if (evalskip) {
skipping:	  if (evalskip == SKIPCONT && --skipcount <= 0) {
				evalskip = 0;
				continue;
			}
			if (evalskip == SKIPBREAK && --skipcount <= 0)
				evalskip = 0;
			break;
		}
		i = exitstatus;
		if (n->type != NWHILE)
			i = !i;
		if (i != 0)
			break;
		evaltree(n->nbinary.ch2, flags);
		status = exitstatus;
		if (evalskip)
			goto skipping;
	}
	loopnest--;
	exitstatus = status;
}



STATIC void
evalfor(union node *n, int flags)
{
	struct arglist arglist;
	union node *argp;
	struct strlist *sp;
	struct stackmark smark;

	setstackmark(&smark);
	arglist.lastp = &arglist.list;
	for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
		/* XXX */
		if (evalskip)
			goto out;
	}
	*arglist.lastp = NULL;

	exitstatus = 0;
	loopnest++;
	flags &= EV_TESTED;
	for (sp = arglist.list ; sp ; sp = sp->next) {
		setvar(n->nfor.var, sp->text, 0);
		evaltree(n->nfor.body, flags);
		if (evalskip) {
			if (evalskip == SKIPCONT && --skipcount <= 0) {
				evalskip = 0;
				continue;
			}
			if (evalskip == SKIPBREAK && --skipcount <= 0)
				evalskip = 0;
			break;
		}
	}
	loopnest--;
out:
	popstackmark(&smark);
}



STATIC void
evalcase(union node *n, int flags)
{
	union node *cp;
	union node *patp;
	struct arglist arglist;
	struct stackmark smark;

	setstackmark(&smark);
	arglist.lastp = &arglist.list;
	expandarg(n->ncase.expr, &arglist, EXP_TILDE);
	exitstatus = 0;
	for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
		for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
			if (casematch(patp, arglist.list->text)) {
				if (evalskip == 0) {
					evaltree(cp->nclist.body, flags);
				}
				goto out;
			}
		}
	}
out:
	popstackmark(&smark);
}



/*
 * Kick off a subshell to evaluate a tree.
 */

STATIC void
evalsubshell(union node *n, int flags)
{
	struct job *jp;
	int backgnd = (n->type == NBACKGND);
	int status;

	expredir(n->nredir.redirect);
	if (!backgnd && flags & EV_EXIT && !trap[0])
		goto nofork;
	INTOFF;
	jp = makejob(n, 1);
	if (forkshell(jp, n, backgnd) == 0) {
		INTON;
		flags |= EV_EXIT;
		if (backgnd)
			flags &=~ EV_TESTED;
nofork:
		redirect(n->nredir.redirect, 0);
		evaltreenr(n->nredir.n, flags);
		/* never returns */
	}
	status = 0;
	if (! backgnd)
		status = waitforjob(jp);
	exitstatus = status;
	INTON;
}



/*
 * Compute the names of the files in a redirection list.
 */

STATIC void
expredir(union node *n)
{
	union node *redir;

	for (redir = n ; redir ; redir = redir->nfile.next) {
		struct arglist fn;
		fn.lastp = &fn.list;
		switch (redir->type) {
		case NFROMTO:
		case NFROM:
		case NTO:
		case NCLOBBER:
		case NAPPEND:
			expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
			redir->nfile.expfname = fn.list->text;
			break;
		case NFROMFD:
		case NTOFD:
			if (redir->ndup.vname) {
				expandarg(redir->ndup.vname, &fn, EXP_FULL | EXP_TILDE);
				fixredir(redir, fn.list->text, 1);
			}
			break;
		}
	}
}



/*
 * Evaluate a pipeline.  All the processes in the pipeline are children
 * of the process creating the pipeline.  (This differs from some versions
 * of the shell, which make the last process in a pipeline the parent
 * of all the rest.)
 */

STATIC void
evalpipe(union node *n, int flags)
{
	struct job *jp;
	struct nodelist *lp;
	int pipelen;
	int prevfd;
	int pip[2];

	TRACE(("evalpipe(0x%lx) called\n", (long)n));
	pipelen = 0;
	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
		pipelen++;
	flags |= EV_EXIT;
	INTOFF;
	jp = makejob(n, pipelen);
	prevfd = -1;
	for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
		prehash(lp->n);
		pip[1] = -1;
		if (lp->next) {
			if (pipe(pip) < 0) {
				close(prevfd);
				sh_error("Pipe call failed");
			}
		}
		if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
			INTON;
			if (pip[1] >= 0) {
				close(pip[0]);
			}
			if (prevfd > 0) {
				dup2(prevfd, 0);
				close(prevfd);
			}
			if (pip[1] > 1) {
				dup2(pip[1], 1);
				close(pip[1]);
			}
			evaltreenr(lp->n, flags);
			/* never returns */
		}
		if (prevfd >= 0)
			close(prevfd);
		prevfd = pip[0];
		close(pip[1]);
	}
	if (n->npipe.backgnd == 0) {
		exitstatus = waitforjob(jp);
		TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
	}
	INTON;
}



/*
 * Execute a command inside back quotes.  If it's a builtin command, we
 * want to save its output in a block obtained from malloc.  Otherwise
 * we fork off a subprocess and get the output of the command via a pipe.
 * Should be called with interrupts off.
 */

void
evalbackcmd(union node *n, struct backcmd *result)
{
	result->fd = -1;
	result->buf = NULL;
	result->nleft = 0;
	result->jp = NULL;
	if (n == NULL) {
		goto out;
	}

#ifdef notyet
	/*
	 * For now we disable executing builtins in the same
	 * context as the shell, because we are not keeping
	 * enough state to recover from changes that are
	 * supposed only to affect subshells. eg. echo "`cd /`"
	 */
	if (n->type == NCMD) {
		struct ifsregion saveifs;
		struct ifsregion *savelastp;
		struct nodelist *saveargbackq;

		saveifs = ifsfirst;
		savelastp = ifslastp;
		saveargbackq = argbackq;

		exitstatus = oexitstatus;
		evalcommand(n, EV_BACKCMD, result);

		ifsfirst = saveifs;
		ifslastp = savelastp;
		argbackq = saveargbackq;
	} else
#endif
	{
		int pip[2];
		struct job *jp;

		if (pipe(pip) < 0)
			sh_error("Pipe call failed");
		jp = makejob(n, 1);
		if (forkshell(jp, n, FORK_NOJOB) == 0) {
			FORCEINTON;
			close(pip[0]);
			if (pip[1] != 1) {
				dup2(pip[1], 1);
				close(pip[1]);
			}
			eflag = 0;
			evaltreenr(n, EV_EXIT);
			/* NOTREACHED */
		}
		close(pip[1]);
		result->fd = pip[0];
		result->jp = jp;
	}
out:
	TRACE(("evalbackcmd done: fd=%d buf=0x%x nleft=%d jp=0x%x\n",
		result->fd, result->buf, result->nleft, result->jp));
}

static char **
parse_command_args(char **argv, const char **path)
{
	char *cp, c;

	for (;;) {
		cp = *++argv;
		if (!cp)
			return 0;
		if (*cp++ != '-')
			break;
		if (!(c = *cp++))
			break;
		if (c == '-' && !*cp) {
			argv++;
			break;
		}
		do {
			switch (c) {
			case 'p':
				*path = defpath;
				break;
			default:
				/* run 'typecmd' for other options */
				return 0;
			}
		} while ((c = *cp++));
	}
	return argv;
}



/*
 * Execute a simple command.
 */

STATIC void
#ifdef notyet
evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
#else
evalcommand(union node *cmd, int flags)
#endif
{
	struct stackmark smark;
	union node *argp;
	struct arglist arglist;
	struct arglist varlist;
	char **argv;
	int argc;
	struct strlist *sp;
#ifdef notyet
	int pip[2];
#endif
	struct cmdentry cmdentry;
	struct job *jp;
	char *lastarg;
	const char *path;
	int spclbltin;
	int execcmd;
	int status;
	char **nargv;

	/* First expand the arguments. */
	TRACE(("evalcommand(0x%lx, %d) called\n", (long)cmd, flags));
	setstackmark(&smark);
	back_exitstatus = 0;

	cmdentry.cmdtype = CMDBUILTIN;
	cmdentry.u.cmd = &bltin;
	varlist.lastp = &varlist.list;
	*varlist.lastp = NULL;
	arglist.lastp = &arglist.list;
	*arglist.lastp = NULL;

	argc = 0;
	for (argp = cmd->ncmd.args; argp; argp = argp->narg.next) {
		struct strlist **spp;

		spp = arglist.lastp;
		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
		for (sp = *spp; sp; sp = sp->next)
			argc++;
	}

	/* Reserve one extra spot at the front for shellexec. */
	nargv = stalloc(sizeof (char *) * (argc + 2));
	argv = ++nargv;
	for (sp = arglist.list ; sp ; sp = sp->next) {
		TRACE(("evalcommand arg: %s\n", sp->text));
		*nargv++ = sp->text;
	}
	*nargv = NULL;

	lastarg = NULL;
	if (iflag && funcnest == 0 && argc > 0)
		lastarg = nargv[-1];

	preverrout.fd = 2;
	expredir(cmd->ncmd.redirect);
	status = redirectsafe(cmd->ncmd.redirect, REDIR_PUSH|REDIR_SAVEFD2);

	path = vpath.text;
	for (argp = cmd->ncmd.assign; argp; argp = argp->narg.next) {
		struct strlist **spp;
		char *p;

		spp = varlist.lastp;
		expandarg(argp, &varlist, EXP_VARTILDE);

		/*
		 * Modify the command lookup path, if a PATH= assignment
		 * is present
		 */
		p = (*spp)->text;
		if (varequal(p, path))
			path = p;
	}

	/* Print the command if xflag is set. */
	if (xflag) {
		struct output *out;
		int sep;

		out = &preverrout;
		outstr(expandstr(ps4val()), out);
		sep = 0;
		sep = eprintlist(out, varlist.list, sep);
		eprintlist(out, arglist.list, sep);
		outcslow('\n', out);
#ifdef FLUSHERR
		flushout(out);
#endif
	}

	execcmd = 0;
	spclbltin = -1;

	/* Now locate the command. */
	if (argc) {
		const char *oldpath;
		int cmd_flag = DO_ERR;

		path += 5;
		oldpath = path;
		for (;;) {
			find_command(argv[0], &cmdentry, cmd_flag, path);
			if (cmdentry.cmdtype == CMDUNKNOWN) {
				status = 127;
#ifdef FLUSHERR
				flushout(&errout);
#endif
				goto bail;
			}

			/* implement bltin and command here */
			if (cmdentry.cmdtype != CMDBUILTIN)
				break;
			if (spclbltin < 0)
				spclbltin = 
					cmdentry.u.cmd->flags &
					BUILTIN_SPECIAL
				;
			if (cmdentry.u.cmd == EXECCMD)
				execcmd++;
			if (cmdentry.u.cmd != COMMANDCMD)
				break;

			path = oldpath;
			nargv = parse_command_args(argv, &path);
			if (!nargv)
				break;
			argc -= nargv - argv;
			argv = nargv;
			cmd_flag |= DO_NOFUNC;
		}
	}

	if (status) {
		/* We have a redirection error. */
		if (spclbltin > 0)
			exraise(EXERROR);
bail:
		exitstatus = status;
		goto out;
	}

	/* Execute the command. */
	switch (cmdentry.cmdtype) {
	default:
		/* Fork off a child process if necessary. */
		if (!(flags & EV_EXIT) || trap[0]) {
			INTOFF;
			jp = makejob(cmd, 1);
			if (forkshell(jp, cmd, FORK_FG) != 0) {
				exitstatus = waitforjob(jp);
				INTON;
				break;
			}
			FORCEINTON;
		}
		listsetvar(varlist.list, VEXPORT|VSTACK);
		shellexec(argv, path, cmdentry.u.index);
		/* NOTREACHED */

	case CMDBUILTIN:
		cmdenviron = varlist.list;
		if (cmdenviron) {
			struct strlist *list = cmdenviron;
			int i = VNOSET;
			if (spclbltin > 0 || argc == 0) {
				i = 0;
				if (execcmd && argc > 1)
					i = VEXPORT;
			}
			listsetvar(list, i);
		}
		if (evalbltin(cmdentry.u.cmd, argc, argv)) {
			int status;
			int i, j;

			i = exception;
			if (i == EXEXIT)
				goto raise;

			status = 2;
			j = 0;
			if (i == EXINT)
				j = SIGINT;
			if (i == EXSIG)
				j = pendingsigs;
			if (j)
				status = j + 128;
			exitstatus = status;

			if (i == EXINT || spclbltin > 0) {
raise:
				longjmp(handler->loc, 1);
			}
			FORCEINTON;
		}
		break;

	case CMDFUNCTION:
		listsetvar(varlist.list, 0);
		if (evalfun(cmdentry.u.func, argc, argv, flags))
			goto raise;
		break;
	}

out:
	popredir(execcmd);
	if (lastarg)
		/* dsl: I think this is intended to be used to support
		 * '_' in 'vi' command mode during line editing...
		 * However I implemented that within libedit itself.
		 */
		setvar("_", lastarg, 0);
	popstackmark(&smark);
}

STATIC int
evalbltin(const struct builtincmd *cmd, int argc, char **argv) {
	char *volatile savecmdname;
	struct jmploc *volatile savehandler;
	struct jmploc jmploc;
	int i;

	savecmdname = commandname;
	if ((i = setjmp(jmploc.loc)))
		goto cmddone;
	savehandler = handler;
	handler = &jmploc;
	commandname = argv[0];
	argptr = argv + 1;
	optptr = NULL;			/* initialize nextopt */
	exitstatus = (*cmd->builtin)(argc, argv);
	flushall();
cmddone:
	exitstatus |= outerr(out1);
	freestdout();
	commandname = savecmdname;
	exsig = 0;
	handler = savehandler;

	return i;
}

STATIC int
evalfun(struct funcnode *func, int argc, char **argv, int flags)
{
	volatile struct shparam saveparam;
	struct localvar *volatile savelocalvars;
	struct jmploc *volatile savehandler;
	struct jmploc jmploc;
	int e;

	saveparam = shellparam;
	savelocalvars = localvars;
	if ((e = setjmp(jmploc.loc))) {
		goto funcdone;
	}
	INTOFF;
	savehandler = handler;
	handler = &jmploc;
	localvars = NULL;
	shellparam.malloc = 0;
	func->count++;
	funcnest++;
	INTON;
	shellparam.nparam = argc - 1;
	shellparam.p = argv + 1;
	shellparam.optind = 1;
	shellparam.optoff = -1;
	evaltree(&func->n, flags & EV_TESTED);
funcdone:
	INTOFF;
	funcnest--;
	freefunc(func);
	poplocalvars();
	localvars = savelocalvars;
	freeparam(&shellparam);
	shellparam = saveparam;
	handler = savehandler;
	INTON;
	evalskip &= ~SKIPFUNC;
	return e;
}


/*
 * Search for a command.  This is called before we fork so that the
 * location of the command will be available in the parent as well as
 * the child.  The check for "goodname" is an overly conservative
 * check that the name will not be subject to expansion.
 */

STATIC void
prehash(union node *n)
{
	struct cmdentry entry;

	if (n->type == NCMD && n->ncmd.args)
		if (goodname(n->ncmd.args->narg.text))
			find_command(n->ncmd.args->narg.text, &entry, 0,
				     pathval());
}



/*
 * Builtin commands.  Builtin commands whose functions are closely
 * tied to evaluation are implemented here.
 */

/*
 * No command given.
 */

STATIC int
bltincmd(int argc, char **argv)
{
	/*
	 * Preserve exitstatus of a previous possible redirection
	 * as POSIX mandates
	 */
	return back_exitstatus;
}


/*
 * Handle break and continue commands.  Break, continue, and return are
 * all handled by setting the evalskip flag.  The evaluation routines
 * above all check this flag, and if it is set they start skipping
 * commands rather than executing them.  The variable skipcount is
 * the number of loops to break/continue, or the number of function
 * levels to return.  (The latter is always 1.)  It should probably
 * be an error to break out of more loops than exist, but it isn't
 * in the standard shell so we don't make it one here.
 */

int
breakcmd(int argc, char **argv)
{
	int n = argc > 1 ? number(argv[1]) : 1;

	if (n <= 0)
		badnum(argv[1]);
	if (n > loopnest)
		n = loopnest;
	if (n > 0) {
		evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
		skipcount = n;
	}
	return 0;
}


/*
 * The return command.
 */

int
returncmd(int argc, char **argv)
{
	/*
	 * If called outside a function, do what ksh does;
	 * skip the rest of the file.
	 */
	evalskip = funcnest ? SKIPFUNC : SKIPFILE;
	return argv[1] ? number(argv[1]) : exitstatus;
}


int
falsecmd(int argc, char **argv)
{
	return 1;
}


int
truecmd(int argc, char **argv)
{
	return 0;
}


int
execcmd(int argc, char **argv)
{
	if (argc > 1) {
		iflag = 0;		/* exit on error */
		mflag = 0;
		optschanged();
		shellexec(argv + 1, pathval(), 0);
	}
	return 0;
}


STATIC int
eprintlist(struct output *out, struct strlist *sp, int sep)
{
	while (sp) {
		const char *p;

		p = " %s" + (1 - sep);
		sep |= 1;
		outfmt(out, p, sp->text);
		sp = sp->next;
	}

	return sep;
}