aboutsummaryrefslogtreecommitdiff
path: root/hush.c
blob: 9a43a03dc958f4d0fb8b3e97725fa1bdac61c5f3 (plain)
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
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
/* vi: set sw=4 ts=4: */
/*
 * sh.c -- a prototype Bourne shell grammar parser
 *      Intended to follow the original Thompson and Ritchie
 *      "small and simple is beautiful" philosophy, which
 *      incidentally is a good match to today's BusyBox.
 *
 * Copyright (C) 2000,2001  Larry Doolittle  <larry@doolittle.boa.org>
 *
 * Credits:
 *      The parser routines proper are all original material, first
 *      written Dec 2000 and Jan 2001 by Larry Doolittle.
 *      The execution engine, the builtins, and much of the underlying
 *      support has been adapted from busybox-0.49pre's lash,
 *      which is Copyright (C) 2000 by Lineo, Inc., and
 *      written by Erik Andersen <andersen@lineo.com>, <andersee@debian.org>.
 *      That, in turn, is based in part on ladsh.c, by Michael K. Johnson and
 *      Erik W. Troan, which they placed in the public domain.  I don't know
 *      how much of the Johnson/Troan code has survived the repeated rewrites.
 * Other credits:
 *      simple_itoa() was lifted from boa-0.93.15
 *      b_addchr() derived from similar w_addchar function in glibc-2.2
 *      setup_redirect(), redirect_opt_num(), and big chunks of main()
 *        and many builtins derived from contributions by Erik Andersen
 *      miscellaneous bugfixes from Matt Kraai
 *
 * There are two big (and related) architecture differences between
 * this parser and the lash parser.  One is that this version is
 * actually designed from the ground up to understand nearly all
 * of the Bourne grammar.  The second, consequential change is that
 * the parser and input reader have been turned inside out.  Now,
 * the parser is in control, and asks for input as needed.  The old
 * way had the input reader in control, and it asked for parsing to
 * take place as needed.  The new way makes it much easier to properly
 * handle the recursion implicit in the various substitutions, especially
 * across continuation lines.
 *
 * Bash grammar not implemented: (how many of these were in original sh?)
 *      $@ (those sure look like weird quoting rules)
 *      $_
 *      ! negation operator for pipes
 *      &> and >& redirection of stdout+stderr
 *      Brace Expansion
 *      Tilde Expansion
 *      fancy forms of Parameter Expansion
 *      Arithmetic Expansion
 *      <(list) and >(list) Process Substitution
 *      reserved words: if, then, elif, else, fi, while, until, for,
 *                      do, done, case
 *      Here Documents ( << word )
 *      Functions
 * Major bugs:
 *      job handling woefully incomplete and buggy
 *      reserved word execution woefully incomplete and buggy
 *      incomplete reserved word sequence doesn't request more lines of input
 * to-do:
 *      port selected bugfixes from post-0.49 busybox lash
 *      finish implementing reserved words
 *      handle children going into background
 *      clean up recognition of null pipes
 *      have builtin_exec set flag to avoid restore_redirects
 *      figure out if "echo foo}" is fixable
 *      check setting of global_argc and global_argv
 *      control-C handling, probably with longjmp
 *      VAR=value prefix for simple commands
 *      follow IFS rules more precisely, including update semantics
 *      write builtin_eval, builtin_ulimit, builtin_umask
 *      figure out what to do with backslash-newline
 *      explain why we use signal instead of sigaction
 *      propagate syntax errors, die on resource errors?
 *      continuation lines, both explicit and implicit - done?
 *      memory leak finding and plugging - done?
 *      more testing, especially quoting rules and redirection
 *      maybe change map[] to use 2-bit entries
 *      (eventually) remove all the printf's
 *      more integration with BusyBox: prompts, cmdedit, applets
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
#include <ctype.h>     /* isalpha, isdigit */
#include <unistd.h>    /* getpid */
#include <stdlib.h>    /* getenv, atoi */
#include <string.h>    /* strchr */
#include <stdio.h>     /* popen etc. */
#include <glob.h>      /* glob, of course */
#include <stdarg.h>    /* va_list */
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>    /* should be pretty obvious */

#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>

/* #include <dmalloc.h> */
/* #define DEBUG_SHELL */

#ifdef BB_VER
#include "busybox.h"
#include "cmdedit.h"
#else
#define applet_name "hush"
#include "standalone.h"
#define shell_main main
#define BB_FEATURE_SH_SIMPLE_PROMPT
#endif

typedef enum {
	REDIRECT_INPUT     = 1,
	REDIRECT_OVERWRITE = 2,
	REDIRECT_APPEND    = 3,
	REDIRECT_HEREIS    = 4,
	REDIRECT_IO        = 5
} redir_type;

/* The descrip member of this structure is only used to make debugging
 * output pretty */
struct {int mode; int default_fd; char *descrip;} redir_table[] = {
	{ 0,                         0, "()" },
	{ O_RDONLY,                  0, "<"  },
	{ O_CREAT|O_TRUNC|O_WRONLY,  1, ">"  },
	{ O_CREAT|O_APPEND|O_WRONLY, 1, ">>" },
	{ O_RDONLY,                 -1, "<<" },
	{ O_RDWR,                    1, "<>" }
};

typedef enum {
	PIPE_SEQ = 1,
	PIPE_AND = 2,
	PIPE_OR  = 3,
	PIPE_BG  = 4,
} pipe_style;

/* might eventually control execution */
typedef enum {
	RES_NONE  = 0,
	RES_IF    = 1,
	RES_THEN  = 2,
	RES_ELIF  = 3,
	RES_ELSE  = 4,
	RES_FI    = 5,
	RES_FOR   = 6,
	RES_WHILE = 7,
	RES_UNTIL = 8,
	RES_DO    = 9,
	RES_DONE  = 10,
	RES_XXXX  = 11,
	RES_SNTX  = 12
} reserved_style;
#define FLAG_END   (1<<RES_NONE)
#define FLAG_IF    (1<<RES_IF)
#define FLAG_THEN  (1<<RES_THEN)
#define FLAG_ELIF  (1<<RES_ELIF)
#define FLAG_ELSE  (1<<RES_ELSE)
#define FLAG_FI    (1<<RES_FI)
#define FLAG_FOR   (1<<RES_FOR)
#define FLAG_WHILE (1<<RES_WHILE)
#define FLAG_UNTIL (1<<RES_UNTIL)
#define FLAG_DO    (1<<RES_DO)
#define FLAG_DONE  (1<<RES_DONE)
#define FLAG_START (1<<RES_XXXX)

/* This holds pointers to the various results of parsing */
struct p_context {
	struct child_prog *child;
	struct pipe *list_head;
	struct pipe *pipe;
	struct redir_struct *pending_redirect;
	reserved_style w;
	int old_flag;				/* for figuring out valid reserved words */
	struct p_context *stack;
	/* How about quoting status? */
};

struct redir_struct {
	redir_type type;			/* type of redirection */
	int fd;						/* file descriptor being redirected */
	int dup;					/* -1, or file descriptor being duplicated */
	struct redir_struct *next;	/* pointer to the next redirect in the list */ 
	glob_t word;				/* *word.gl_pathv is the filename */
};

struct child_prog {
	pid_t pid;					/* 0 if exited */
	char **argv;				/* program name and arguments */
	struct pipe *group;			/* if non-NULL, first in group or subshell */
	int subshell;				/* flag, non-zero if group must be forked */
	struct redir_struct *redirects;	/* I/O redirections */
	glob_t glob_result;			/* result of parameter globbing */
	int is_stopped;				/* is the program currently running? */
	struct pipe *family;		/* pointer back to the child's parent pipe */
};

struct pipe {
	int jobid;					/* job number */
	int num_progs;				/* total number of programs in job */
	int running_progs;			/* number of programs running */
	char *text;					/* name of job */
	char *cmdbuf;				/* buffer various argv's point into */
	pid_t pgrp;					/* process group ID for the job */
	struct child_prog *progs;	/* array of commands in pipe */
	struct pipe *next;			/* to track background commands */
	int stopped_progs;			/* number of programs alive, but stopped */
	int job_context;			/* bitmask defining current context */
	pipe_style followup;		/* PIPE_BG, PIPE_SEQ, PIPE_OR, PIPE_AND */
	reserved_style r_mode;		/* supports if, for, while, until */
	struct jobset *job_list;
};

struct jobset {
	struct pipe *head;			/* head of list of running jobs */
	struct pipe *fg;			/* current foreground job */
};

struct close_me {
	int fd;
	struct close_me *next;
};

/* globals, connect us to the outside world
 * the first three support $?, $#, and $1 */
char **global_argv;
unsigned int global_argc;
unsigned int last_return_code;
extern char **environ; /* This is in <unistd.h>, but protected with __USE_GNU */
 
/* Variables we export */
unsigned int shell_context;  /* Used in cmdedit.c to reset the
                              * context when someone hits ^C */

/* "globals" within this file */
static char *ifs=NULL;
static char map[256];
static int fake_mode=0;
static int interactive=0;
static struct close_me *close_me_head = NULL;
static char *cwd;
/* static struct jobset job_list = { NULL, NULL }; */
static unsigned int last_bg_pid=0;
static char *PS1;
static char *PS2 = "> ";

#define B_CHUNK (100)
#define B_NOSPAC 1
#define MAX_LINE 256       /* for cwd */
#define MAX_READ 256       /* for builtin_read */

typedef struct {
	char *data;
	int length;
	int maxlen;
	int quote;
	int nonnull;
} o_string;
#define NULL_O_STRING {NULL,0,0,0,0}
/* used for initialization:
	o_string foo = NULL_O_STRING; */

/* I can almost use ordinary FILE *.  Is open_memstream() universally
 * available?  Where is it documented? */
struct in_str {
	const char *p;
	int __promptme;
	int promptmode;
	FILE *file;
	int (*get) (struct in_str *);
	int (*peek) (struct in_str *);
};
#define b_getch(input) ((input)->get(input))
#define b_peek(input) ((input)->peek(input))

#define JOB_STATUS_FORMAT "[%d] %-22s %.40s\n"

struct built_in_command {
	char *cmd;					/* name */
	char *descr;				/* description */
	int (*function) (struct child_prog *);	/* function ptr */
};

/* belongs in busybox.h */
static inline int max(int a, int b) {
	return (a>b)?a:b;
}

/* This should be in utility.c */
#ifdef DEBUG_SHELL
static void debug_printf(const char *format, ...)
{
	va_list args;
	va_start(args, format);
	vfprintf(stderr, format, args);
	va_end(args);
}
#else
static void debug_printf(const char *format, ...) { }
#endif
#define final_printf debug_printf

void __syntax(char *file, int line) {
	fprintf(stderr,"syntax error %s:%d\n",file,line);
}
#define syntax() __syntax(__FILE__, __LINE__)

/* Index of subroutines: */
/*   function prototypes for builtins */
static int builtin_cd(struct child_prog *child);
static int builtin_env(struct child_prog *child);
static int builtin_exec(struct child_prog *child);
static int builtin_exit(struct child_prog *child);
static int builtin_export(struct child_prog *child);
static int builtin_fg_bg(struct child_prog *child);
static int builtin_help(struct child_prog *child);
static int builtin_jobs(struct child_prog *child);
static int builtin_pwd(struct child_prog *child);
static int builtin_read(struct child_prog *child);
static int builtin_shift(struct child_prog *child);
static int builtin_source(struct child_prog *child);
static int builtin_ulimit(struct child_prog *child);
static int builtin_umask(struct child_prog *child);
static int builtin_unset(struct child_prog *child);
/*   o_string manipulation: */
static int b_check_space(o_string *o, int len);
static int b_addchr(o_string *o, int ch);
static void b_reset(o_string *o);
static int b_addqchr(o_string *o, int ch, int quote);
static int b_adduint(o_string *o, unsigned int i);
/*  in_str manipulations: */
static int static_get(struct in_str *i);
static int static_peek(struct in_str *i);
static int file_get(struct in_str *i);
static int file_peek(struct in_str *i);
static void setup_file_in_str(struct in_str *i, FILE *f);
static void setup_string_in_str(struct in_str *i, const char *s);
/*  close_me manipulations: */
static void mark_open(int fd);
static void mark_closed(int fd);
static void close_all();
/*  "run" the final data structures: */
static char *indenter(int i);
static int run_list_test(struct pipe *head, int indent);
static int run_pipe_test(struct pipe *pi, int indent);
/*  really run the final data structures: */
static int setup_redirects(struct child_prog *prog, int squirrel[]);
static int pipe_wait(struct pipe *pi);
static int run_list_real(struct pipe *pi);
static void pseudo_exec(struct child_prog *child) __attribute__ ((noreturn));
static int run_pipe_real(struct pipe *pi);
/*   extended glob support: */
static int globhack(const char *src, int flags, glob_t *pglob);
static int glob_needed(const char *s);
static int xglob(o_string *dest, int flags, glob_t *pglob);
/*   data structure manipulation: */
static int setup_redirect(struct p_context *ctx, int fd, redir_type style, struct in_str *input);
static void initialize_context(struct p_context *ctx);
static int done_word(o_string *dest, struct p_context *ctx);
static int done_command(struct p_context *ctx);
static int done_pipe(struct p_context *ctx, pipe_style type);
/*   primary string parsing: */
static int redirect_dup_num(struct in_str *input);
static int redirect_opt_num(o_string *o);
static int process_command_subs(o_string *dest, struct p_context *ctx, struct in_str *input, int subst_end);
static int parse_group(o_string *dest, struct p_context *ctx, struct in_str *input, int ch);
static void lookup_param(o_string *dest, struct p_context *ctx, o_string *src);
static int handle_dollar(o_string *dest, struct p_context *ctx, struct in_str *input);
static int parse_string(o_string *dest, struct p_context *ctx, const char *src);
static int parse_stream(o_string *dest, struct p_context *ctx, struct in_str *input0, int end_trigger);
/*   setup: */
static int parse_stream_outer(struct in_str *inp);
static int parse_string_outer(const char *s);
static int parse_file_outer(FILE *f);

/* Table of built-in functions.  They can be forked or not, depending on
 * context: within pipes, they fork.  As simple commands, they do not.
 * When used in non-forking context, they can change global variables
 * in the parent shell process.  If forked, of course they can not.
 * For example, 'unset foo | whatever' will parse and run, but foo will
 * still be set at the end. */
static struct built_in_command bltins[] = {
	{"bg", "Resume a job in the background", builtin_fg_bg},
	{"cd", "Change working directory", builtin_cd},
	{"env", "Print all environment variables", builtin_env},
	{"exec", "Exec command, replacing this shell with the exec'd process", builtin_exec},
	{"exit", "Exit from shell()", builtin_exit},
	{"export", "Set environment variable", builtin_export},
	{"fg", "Bring job into the foreground", builtin_fg_bg},
	{"jobs", "Lists the active jobs", builtin_jobs},
	{"pwd", "Print current directory", builtin_pwd},
	{"read", "Input environment variable", builtin_read},
	{"shift", "Shift positional parameters", builtin_shift},
	{"ulimit","Controls resource limits", builtin_ulimit},
	{"umask","Sets file creation mask", builtin_umask},
	{"unset", "Unset environment variable", builtin_unset},
	{".", "Source-in and run commands in a file", builtin_source},
	{"help", "List shell built-in commands", builtin_help},
	{NULL, NULL, NULL}
};

/* built-in 'cd <path>' handler */
static int builtin_cd(struct child_prog *child)
{
	char *newdir;
	if (child->argv[1] == NULL)
		newdir = getenv("HOME");
	else
		newdir = child->argv[1];
	if (chdir(newdir)) {
		printf("cd: %s: %s\n", newdir, strerror(errno));
		return EXIT_FAILURE;
	}
	getcwd(cwd, sizeof(char)*MAX_LINE);
	return EXIT_SUCCESS;
}

/* built-in 'env' handler */
static int builtin_env(struct child_prog *dummy)
{
	char **e = environ;
	if (e == NULL) return EXIT_FAILURE;
	for (; *e; e++) {
		puts(*e);
	}
	return EXIT_SUCCESS;
}

/* built-in 'exec' handler */
static int builtin_exec(struct child_prog *child)
{
	if (child->argv[1] == NULL)
		return EXIT_SUCCESS;   /* Really? */
	child->argv++;
	pseudo_exec(child);
	/* never returns */
}

/* built-in 'exit' handler */
static int builtin_exit(struct child_prog *child)
{
	if (child->argv[1] == NULL)
		exit(EXIT_SUCCESS);
	exit (atoi(child->argv[1]));
}

/* built-in 'export VAR=value' handler */
static int builtin_export(struct child_prog *child)
{
	int res;

	if (child->argv[1] == NULL) {
		return (builtin_env(child));
	}
	res = putenv(child->argv[1]);
	if (res)
		fprintf(stderr, "export: %s\n", strerror(errno));
	return (res);
}

/* built-in 'fg' and 'bg' handler */
static int builtin_fg_bg(struct child_prog *child)
{
	int i, jobNum;
	struct pipe *job=NULL;
	
	if (!child->argv[1] || child->argv[2]) {
		error_msg("%s: exactly one argument is expected\n",
				child->argv[0]);
		return EXIT_FAILURE;
	}

	if (sscanf(child->argv[1], "%%%d", &jobNum) != 1) {
		error_msg("%s: bad argument '%s'\n",
				child->argv[0], child->argv[1]);
		return EXIT_FAILURE;
	}

	for (job = child->family->job_list->head; job; job = job->next) {
		if (job->jobid == jobNum) {
			break;
		}
	}

	if (!job) {
		error_msg("%s: unknown job %d\n",
				child->argv[0], jobNum);
		return EXIT_FAILURE;
	}

	if (*child->argv[0] == 'f') {
		/* Make this job the foreground job */
		/* suppress messages when run from /linuxrc mag@sysgo.de */
		if (tcsetpgrp(0, job->pgrp) && errno != ENOTTY)
			perror_msg("tcsetpgrp"); 
		child->family->job_list->fg = job;
	}

	/* Restart the processes in the job */
	for (i = 0; i < job->num_progs; i++)
		job->progs[i].is_stopped = 0;

	kill(-job->pgrp, SIGCONT);

	job->stopped_progs = 0;
	return EXIT_SUCCESS;
}

/* built-in 'help' handler */
static int builtin_help(struct child_prog *dummy)
{
	struct built_in_command *x;

	printf("\nBuilt-in commands:\n");
	printf("-------------------\n");
	for (x = bltins; x->cmd; x++) {
		if (x->descr==NULL)
			continue;
		printf("%s\t%s\n", x->cmd, x->descr);
	}
	printf("\n\n");
	return EXIT_SUCCESS;
}

/* built-in 'jobs' handler */
static int builtin_jobs(struct child_prog *child)
{
	struct pipe *job;
	char *status_string;

	for (job = child->family->job_list->head; job; job = job->next) {
		if (job->running_progs == job->stopped_progs)
			status_string = "Stopped";
		else
			status_string = "Running";
		printf(JOB_STATUS_FORMAT, job->jobid, status_string, job->text);
	}
	return EXIT_SUCCESS;
}


/* built-in 'pwd' handler */
static int builtin_pwd(struct child_prog *dummy)
{
	getcwd(cwd, MAX_LINE);
	puts(cwd);
	return EXIT_SUCCESS;
}

/* built-in 'read VAR' handler */
static int builtin_read(struct child_prog *child)
{
	int res = 0, len, newlen;
	char *s;
	char string[MAX_READ];

	if (child->argv[1]) {
		/* argument (VAR) given: put "VAR=" into buffer */
		strcpy(string, child->argv[1]);
		len = strlen(string);
		string[len++] = '=';
		string[len]   = '\0';
		/* XXX would it be better to go through in_str? */
		fgets(&string[len], sizeof(string) - len, stdin);	/* read string */
		newlen = strlen(string);
		if(newlen > len)
			string[--newlen] = '\0';	/* chomp trailing newline */
		/*
		** string should now contain "VAR=<value>"
		** copy it (putenv() won't do that, so we must make sure
		** the string resides in a static buffer!)
		*/
		res = -1;
		if((s = strdup(string)))
			res = putenv(s);
		if (res)
			fprintf(stderr, "read: %s\n", strerror(errno));
	}
	else
		fgets(string, sizeof(string), stdin);

	return (res);
}

/* Built-in 'shift' handler */
static int builtin_shift(struct child_prog *child)
{
	int n=1;
	if (child->argv[1]) {
		n=atoi(child->argv[1]);
	}
	if (n>=0 && n<global_argc) {
		/* XXX This probably breaks $0 */
		global_argc -= n;
		global_argv += n;
		return EXIT_SUCCESS;
	} else {
		return EXIT_FAILURE;
	}
}

/* Built-in '.' handler (read-in and execute commands from file) */
static int builtin_source(struct child_prog *child)
{
	FILE *input;
	int status;

	if (child->argv[1] == NULL)
		return EXIT_FAILURE;

	/* XXX search through $PATH is missing */
	input = fopen(child->argv[1], "r");
	if (!input) {
		fprintf(stderr, "Couldn't open file '%s'\n", child->argv[1]);
		return EXIT_FAILURE;
	}

	/* Now run the file */
	/* XXX argv and argc are broken; need to save old global_argv
	 * (pointer only is OK!) on this stack frame,
	 * set global_argv=child->argv+1, recurse, and restore. */
	mark_open(fileno(input));
	status = parse_file_outer(input);
	mark_closed(fileno(input));
	fclose(input);
	return (status);
}

static int builtin_ulimit(struct child_prog *child)
{
	printf("builtin_ulimit not written\n");
	return EXIT_FAILURE;
}

static int builtin_umask(struct child_prog *child)
{
	printf("builtin_umask not written\n");
	return EXIT_FAILURE;
}

/* built-in 'unset VAR' handler */
static int builtin_unset(struct child_prog *child)
{
	if (child->argv[1] == NULL) {
		fprintf(stderr, "unset: parameter required.\n");
		return EXIT_FAILURE;
	}
	unsetenv(child->argv[1]);
	return EXIT_SUCCESS;
}

static int b_check_space(o_string *o, int len)
{
	/* It would be easy to drop a more restrictive policy
	 * in here, such as setting a maximum string length */
	if (o->length + len > o->maxlen) {
		char *old_data = o->data;
		/* assert (data == NULL || o->maxlen != 0); */
		o->maxlen += max(2*len, B_CHUNK);
		o->data = realloc(o->data, 1 + o->maxlen);
		if (o->data == NULL) {
			free(old_data);
		}
	}
	return o->data == NULL;
}

static int b_addchr(o_string *o, int ch)
{
	debug_printf("b_addchr: %c %d %p\n", ch, o->length, o);
	if (b_check_space(o, 1)) return B_NOSPAC;
	o->data[o->length] = ch;
	o->length++;
	o->data[o->length] = '\0';
	return 0;
}

static void b_reset(o_string *o)
{
	o->length = 0;
	o->nonnull = 0;
	if (o->data != NULL) *o->data = '\0';
}

static void b_free(o_string *o)
{
	b_reset(o);
	if (o->data != NULL) free(o->data);
	o->data = NULL;
	o->maxlen = 0;
}

/* My analysis of quoting semantics tells me that state information
 * is associated with a destination, not a source.
 */
static int b_addqchr(o_string *o, int ch, int quote)
{
	if (quote && strchr("*?[\\",ch)) {
		int rc;
		rc = b_addchr(o, '\\');
		if (rc) return rc;
	}
	return b_addchr(o, ch);
}

/* belongs in utility.c */
char *simple_itoa(unsigned int i)
{
	/* 21 digits plus null terminator, good for 64-bit or smaller ints */
	static char local[22];
	char *p = &local[21];
	*p-- = '\0';
	do {
		*p-- = '0' + i % 10;
		i /= 10;
	} while (i > 0);
	return p + 1;
}

static int b_adduint(o_string *o, unsigned int i)
{
	int r;
	char *p = simple_itoa(i);
	/* no escape checking necessary */
	do r=b_addchr(o, *p++); while (r==0 && *p);
	return r;
}

static int static_get(struct in_str *i)
{
	int ch=*i->p++;
	if (ch=='\0') return EOF;
	return ch;
}

static int static_peek(struct in_str *i)
{
	return *i->p;
}

static inline void cmdedit_set_initial_prompt(void)
{
#ifdef BB_FEATURE_SH_SIMPLE_PROMPT
	PS1 = NULL;
#else
	PS1 = getenv("PS1");
	if(PS1==0)
		PS1 = "\\w \\$ ";
#endif	
}

static inline void setup_prompt_string(int promptmode, char **prompt_str)
{
	debug_printf("setup_prompt_string %d ",promptmode);
#ifdef BB_FEATURE_SH_SIMPLE_PROMPT
	/* Set up the prompt */
	if (promptmode == 1) {
		if (PS1)
			free(PS1);
		PS1=xmalloc(strlen(cwd)+4);
		sprintf(PS1, "%s %s", cwd, ( geteuid() != 0 ) ?  "$ ":"# ");
		*prompt_str = PS1;
	} else {
		*prompt_str = PS2;
	}
#else
	*prompt_str = (promptmode==0)? PS1 : PS2;
#endif
	debug_printf("result %s\n",*prompt_str);
}

static void get_user_input(struct in_str *i)
{
	char *prompt_str;
	static char the_command[BUFSIZ];

	setup_prompt_string(i->promptmode, &prompt_str);
#ifdef BB_FEATURE_COMMAND_EDITING
	/*
	 ** enable command line editing only while a command line
	 ** is actually being read; otherwise, we'll end up bequeathing
	 ** atexit() handlers and other unwanted stuff to our
	 ** child processes (rob@sysgo.de)
	 */
	cmdedit_read_input(prompt_str, the_command);
	cmdedit_terminate();
#else
	fputs(prompt_str, stdout);
	fflush(stdout);
	the_command[0]=fgetc(i->file);
	the_command[1]='\0';
#endif
	i->p = the_command;
}

/* This is the magic location that prints prompts 
 * and gets data back from the user */
static int file_get(struct in_str *i)
{
	int ch;

	ch = 0;
	/* If there is data waiting, eat it up */
	if (i->p && *i->p) {
		ch=*i->p++;
	} else {
		/* need to double check i->file because we might be doing something
		 * more complicated by now, like sourcing or substituting. */
		if (i->__promptme && interactive && i->file == stdin) {
			get_user_input(i);
			i->promptmode=2;
		}
		i->__promptme = 0;

		if (i->p && *i->p) {
			ch=*i->p++;
		}
		debug_printf("b_getch: got a %d\n", ch);
	}
	if (ch == '\n') i->__promptme=1;
	return ch;
}

/* All the callers guarantee this routine will never be
 * used right after a newline, so prompting is not needed.
 */
static int file_peek(struct in_str *i)
{
	if (i->p && *i->p) {
		return *i->p;
	} else {
		static char buffer;
		buffer = fgetc(i->file);
		i->p = &buffer;
		debug_printf("b_peek: got a %d\n", *i->p);
		return *i->p; 
	}
}

static void setup_file_in_str(struct in_str *i, FILE *f)
{
	i->peek = file_peek;
	i->get = file_get;
	i->__promptme=1;
	i->promptmode=1;
	i->file = f;
	i->p = NULL;
}

static void setup_string_in_str(struct in_str *i, const char *s)
{
	i->peek = static_peek;
	i->get = static_get;
	i->__promptme=1;
	i->promptmode=1;
	i->p = s;
}

static void mark_open(int fd)
{
	struct close_me *new = xmalloc(sizeof(struct close_me));
	new->fd = fd;
	new->next = close_me_head;
	close_me_head = new;
}

static void mark_closed(int fd)
{
	struct close_me *tmp;
	if (close_me_head == NULL || close_me_head->fd != fd)
		error_msg_and_die("corrupt close_me");
	tmp = close_me_head;
	close_me_head = close_me_head->next;
	free(tmp);
}

static void close_all()
{
	struct close_me *c;
	for (c=close_me_head; c; c=c->next) {
		close(c->fd);
	}
	close_me_head = NULL;
}

/* squirrel != NULL means we squirrel away copies of stdin, stdout,
 * and stderr if they are redirected. */
static int setup_redirects(struct child_prog *prog, int squirrel[])
{
	int openfd, mode;
	struct redir_struct *redir;

	for (redir=prog->redirects; redir; redir=redir->next) {
		if (redir->dup == -1) {
			mode=redir_table[redir->type].mode;
			openfd = open(redir->word.gl_pathv[0], mode, 0666);
			if (openfd < 0) {
			/* this could get lost if stderr has been redirected, but
			   bash and ash both lose it as well (though zsh doesn't!) */
				fprintf(stderr,"error opening %s: %s\n", redir->word.gl_pathv[0],
					strerror(errno));
				return 1;
			}
		} else {
			openfd = redir->dup;
		}

		if (openfd != redir->fd) {
			if (squirrel && redir->fd < 3) {
				squirrel[redir->fd] = dup(redir->fd);
			}
			dup2(openfd, redir->fd);
			close(openfd);
		}
	}
	return 0;
}

static void restore_redirects(int squirrel[])
{
	int i, fd;
	for (i=0; i<3; i++) {
		fd = squirrel[i];
		if (fd != -1) {
			/* No error checking.  I sure wouldn't know what
			 * to do with an error if I found one! */
			dup2(fd, i);
			close(fd);
		}
	}
}

/* XXX this definitely needs some more thought, work, and
 * cribbing from other shells */
static int pipe_wait(struct pipe *pi)
{
	int rcode=0, i, pid, running, status;
	running = pi->num_progs;
	while (running) {
		pid=waitpid(-1, &status, 0);
		if (pid < 0) perror_msg_and_die("waitpid");
		for (i=0; i < pi->num_progs; i++) {
			if (pi->progs[i].pid == pid) {
				if (i==pi->num_progs-1) rcode=WEXITSTATUS(status);
				pi->progs[i].pid = 0;
				running--;
				break;
			}
		}
	}
	return rcode;
}

/* very simple version for testing */
static void pseudo_exec(struct child_prog *child)
{
	int rcode;
	struct built_in_command *x;
	if (child->argv) {
		/*
		 * Check if the command matches any of the builtins.
		 * Depending on context, this might be redundant.  But it's
		 * easier to waste a few CPU cycles than it is to figure out
		 * if this is one of those cases.
		 */
		for (x = bltins; x->cmd; x++) {
			if (strcmp(child->argv[0], x->cmd) == 0 ) {
				debug_printf("builtin exec %s\n", child->argv[0]);
				exit(x->function(child));
			}
		}
		debug_printf("exec of %s\n",child->argv[0]);
		execvp(child->argv[0],child->argv);
		perror("execvp");
		exit(1);
	} else if (child->group) {
		debug_printf("runtime nesting to group\n");
		interactive=0;    /* crucial!!!! */
		rcode = run_list_real(child->group);
		/* OK to leak memory by not calling run_list_test,
		 * since this process is about to exit */
		exit(rcode);
	} else {
		/* Can happen.  See what bash does with ">foo" by itself. */
		debug_printf("trying to pseudo_exec null command\n");
		exit(EXIT_SUCCESS);
	}
}

/* run_pipe_real() starts all the jobs, but doesn't wait for anything
 * to finish.  See pipe_wait().
 *
 * return code is normally -1, when the caller has to wait for children
 * to finish to determine the exit status of the pipe.  If the pipe
 * is a simple builtin command, however, the action is done by the
 * time run_pipe_real returns, and the exit code is provided as the
 * return value.
 *
 * The input of the pipe is always stdin, the output is always
 * stdout.  The outpipe[] mechanism in BusyBox-0.48 lash is bogus,
 * because it tries to avoid running the command substitution in
 * subshell, when that is in fact necessary.  The subshell process
 * now has its stdout directed to the input of the appropriate pipe,
 * so this routine is noticeably simpler.
 */
static int run_pipe_real(struct pipe *pi)
{
	int i;
	int nextin, nextout;
	int pipefds[2];				/* pipefds[0] is for reading */
	struct child_prog *child;
	struct built_in_command *x;

	nextin = 0;
	pi->pgrp = 0;

	/* Check if this is a simple builtin (not part of a pipe).
	 * Builtins within pipes have to fork anyway, and are handled in
	 * pseudo_exec.  "echo foo | read bar" doesn't work on bash, either.
	 */
	if (pi->num_progs == 1 && pi->progs[0].argv != NULL) {
		child = & (pi->progs[0]);
		if (child->group && ! child->subshell) {
			int squirrel[] = {-1, -1, -1};
			int rcode;
			debug_printf("non-subshell grouping\n");
			setup_redirects(child, squirrel);
			/* XXX could we merge code with following builtin case,
			 * by creating a pseudo builtin that calls run_list_real? */
			rcode = run_list_real(child->group);
			restore_redirects(squirrel);
			return rcode;
		}
		for (x = bltins; x->cmd; x++) {
			if (strcmp(child->argv[0], x->cmd) == 0 ) {
				int squirrel[] = {-1, -1, -1};
				int rcode;
				debug_printf("builtin inline %s\n", child->argv[0]);
				/* XXX setup_redirects acts on file descriptors, not FILEs.
				 * This is perfect for work that comes after exec().
				 * Is it really safe for inline use?  Experimentally,
				 * things seem to work with glibc. */
				setup_redirects(child, squirrel);
				rcode = x->function(child);
				restore_redirects(squirrel);
				return rcode;
			}
		}
	}

	for (i = 0; i < pi->num_progs; i++) {
		child = & (pi->progs[i]);

		/* pipes are inserted between pairs of commands */
		if ((i + 1) < pi->num_progs) {
			if (pipe(pipefds)<0) perror_msg_and_die("pipe");
			nextout = pipefds[1];
		} else {
			nextout=1;
			pipefds[0] = -1;
		}

		/* XXX test for failed fork()? */
		if (!(child->pid = fork())) {
			close_all();

			if (nextin != 0) {
				dup2(nextin, 0);
				close(nextin);
			}
			if (nextout != 1) {
				dup2(nextout, 1);
				close(nextout);
			}
			if (pipefds[0]!=-1) {
				close(pipefds[0]);  /* opposite end of our output pipe */
			}

			/* Like bash, explicit redirects override pipes,
			 * and the pipe fd is available for dup'ing. */
			setup_redirects(child,NULL);

			pseudo_exec(child);
		}
		if (interactive) {
			/* Put our child in the process group whose leader is the
			 * first process in this pipe. */
			if (pi->pgrp==0) {
				pi->pgrp = child->pid;
			}
			/* Don't check for errors.  The child may be dead already,
			 * in which case setpgid returns error code EACCES. */
			setpgid(child->pid, pi->pgrp);
		}
		/* In the non-interactive case, do nothing.  Leave the children
		 * with the process group that they inherited from us. */
	
		if (nextin != 0)
			close(nextin);
		if (nextout != 1)
			close(nextout);

		/* If there isn't another process, nextin is garbage 
		   but it doesn't matter */
		nextin = pipefds[0];
	}
	return -1;
}

static int run_list_real(struct pipe *pi)
{
	int rcode=0;
	int if_code=0, next_if_code=0;  /* need double-buffer to handle elif */
	reserved_style rmode=RES_NONE;
	for (;pi;pi=pi->next) {
		rmode = pi->r_mode;
		debug_printf("rmode=%d  if_code=%d  next_if_code=%d\n", rmode, if_code, next_if_code);
		if (rmode == RES_THEN || rmode == RES_ELSE) if_code = next_if_code;
		if (rmode == RES_THEN &&  if_code) continue;
		if (rmode == RES_ELSE && !if_code) continue;
		if (rmode == RES_ELIF && !if_code) continue;
		if (pi->num_progs == 0) break;
		rcode = run_pipe_real(pi);
		if (rcode!=-1) {
			/* We only ran a builtin: rcode was set by the return value
			 * of run_pipe_real(), and we don't need to wait for anything. */
		} else if (pi->followup==PIPE_BG) {
			/* XXX check bash's behavior with nontrivial pipes */
			/* XXX compute jobid */
			/* XXX what does bash do with attempts to background builtins? */
			printf("[%d] %d\n", pi->jobid, pi->pgrp);
			last_bg_pid = pi->pgrp;
			rcode = EXIT_SUCCESS;
		} else {
			if (interactive) {
				/* move the new process group into the foreground */
				/* suppress messages when run from /linuxrc mag@sysgo.de */
				signal(SIGTTIN, SIG_IGN);
				signal(SIGTTOU, SIG_IGN);
				if (tcsetpgrp(0, pi->pgrp) && errno != ENOTTY)
					perror_msg("tcsetpgrp");
				rcode = pipe_wait(pi);
				if (tcsetpgrp(0, getpid()) && errno != ENOTTY)
					perror_msg("tcsetpgrp");
				signal(SIGTTIN, SIG_DFL);
				signal(SIGTTOU, SIG_DFL);
			} else {
				rcode = pipe_wait(pi);
			}
		}
		last_return_code=rcode;
		if ( rmode == RES_IF || rmode == RES_ELIF )
			next_if_code=rcode;  /* can be overwritten a number of times */
		if ( (rcode==EXIT_SUCCESS && pi->followup==PIPE_OR) ||
		     (rcode!=EXIT_SUCCESS && pi->followup==PIPE_AND) )
			return rcode;  /* XXX broken if list is part of if/then/else */
	}
	return rcode;
}

/* broken, of course, but OK for testing */
static char *indenter(int i)
{
	static char blanks[]="                                    ";
	return &blanks[sizeof(blanks)-i-1];
}

/* return code is the exit status of the pipe */
static int run_pipe_test(struct pipe *pi, int indent)
{
	char **p;
	struct child_prog *child;
	struct redir_struct *r, *rnext;
	int a, i, ret_code=0;
	char *ind = indenter(indent);
	final_printf("%s run pipe: (pid %d)\n",ind,getpid());
	for (i=0; i<pi->num_progs; i++) {
		child = &pi->progs[i];
		final_printf("%s  command %d:\n",ind,i);
		if (child->argv) {
			for (a=0,p=child->argv; *p; a++,p++) {
				final_printf("%s   argv[%d] = %s\n",ind,a,*p);
			}
			globfree(&child->glob_result);
			child->argv=NULL;
		} else if (child->group) {
			final_printf("%s   begin group (subshell:%d)\n",ind, child->subshell);
			ret_code = run_list_test(child->group,indent+3);
			final_printf("%s   end group\n",ind);
		} else {
			final_printf("%s   (nil)\n",ind);
		}
		for (r=child->redirects; r; r=rnext) {
			final_printf("%s   redirect %d%s", ind, r->fd, redir_table[r->type].descrip);
			if (r->dup == -1) {
				final_printf(" %s\n", *r->word.gl_pathv);
				globfree(&r->word);
			} else {
				final_printf("&%d\n", r->dup);
			}
			rnext=r->next;
			free(r);
		}
		child->redirects=NULL;
	}
	free(pi->progs);   /* children are an array, they get freed all at once */
	pi->progs=NULL;
	return ret_code;
}

static int run_list_test(struct pipe *head, int indent)
{
	int rcode=0;   /* if list has no members */
	struct pipe *pi, *next;
	char *ind = indenter(indent);
	for (pi=head; pi; pi=next) {
		if (pi->num_progs == 0) break;
		final_printf("%s pipe reserved mode %d\n", ind, pi->r_mode);
		rcode = run_pipe_test(pi, indent);
		final_printf("%s pipe followup code %d\n", ind, pi->followup);
		next=pi->next;
		pi->next=NULL;
		free(pi);
	}
	return rcode;	
}

/* Select which version we will use */
static int run_list(struct pipe *pi)
{
	int rcode=0;
	if (fake_mode==0) {
		rcode = run_list_real(pi);
	} 
	/* run_list_test has the side effect of clearing memory
	 * In the long run that function can be merged with run_list_real,
	 * but doing that now would hobble the debugging effort. */
	run_list_test(pi,0);
	return rcode;
}

/* The API for glob is arguably broken.  This routine pushes a non-matching
 * string into the output structure, removing non-backslashed backslashes.
 * If someone can prove me wrong, by performing this function within the
 * original glob(3) api, feel free to rewrite this routine into oblivion.
 * Return code (0 vs. GLOB_NOSPACE) matches glob(3).
 * XXX broken if the last character is '\\', check that before calling.
 */
static int globhack(const char *src, int flags, glob_t *pglob)
{
	int cnt, pathc;
	const char *s;
	char *dest;
	for (cnt=1, s=src; *s; s++) {
		if (*s == '\\') s++;
		cnt++;
	}
	dest = malloc(cnt);
	if (!dest) return GLOB_NOSPACE;
	if (!(flags & GLOB_APPEND)) {
		pglob->gl_pathv=NULL;
		pglob->gl_pathc=0;
		pglob->gl_offs=0;
		pglob->gl_offs=0;
	}
	pathc = ++pglob->gl_pathc;
	pglob->gl_pathv = realloc(pglob->gl_pathv, (pathc+1)*sizeof(*pglob->gl_pathv));
	if (pglob->gl_pathv == NULL) return GLOB_NOSPACE;
	pglob->gl_pathv[pathc-1]=dest;
	pglob->gl_pathv[pathc]=NULL;
	for (s=src; *s; s++, dest++) {
		if (*s == '\\') s++;
		*dest = *s;
	}
	*dest='\0';
	return 0;
}

/* XXX broken if the last character is '\\', check that before calling */
static int glob_needed(const char *s)
{
	for (; *s; s++) {
		if (*s == '\\') s++;
		if (strchr("*[?",*s)) return 1;
	}
	return 0;
}

#if 0
static void globprint(glob_t *pglob)
{
	int i;
	debug_printf("glob_t at %p:\n", pglob);
	debug_printf("  gl_pathc=%d  gl_pathv=%p  gl_offs=%d  gl_flags=%d\n",
		pglob->gl_pathc, pglob->gl_pathv, pglob->gl_offs, pglob->gl_flags);
	for (i=0; i<pglob->gl_pathc; i++)
		debug_printf("pglob->gl_pathv[%d] = %p = %s\n", i,
			pglob->gl_pathv[i], pglob->gl_pathv[i]);
}
#endif

static int xglob(o_string *dest, int flags, glob_t *pglob)
{
	int gr;

 	/* short-circuit for null word */
	/* we can code this better when the debug_printf's are gone */
 	if (dest->length == 0) {
 		if (dest->nonnull) {
 			/* bash man page calls this an "explicit" null */
 			gr = globhack(dest->data, flags, pglob);
 			debug_printf("globhack returned %d\n",gr);
 		} else {
			return 0;
		}
 	} else if (glob_needed(dest->data)) {
		gr = glob(dest->data, flags, NULL, pglob);
		debug_printf("glob returned %d\n",gr);
		if (gr == GLOB_NOMATCH) {
			/* quote removal, or more accurately, backslash removal */
			gr = globhack(dest->data, flags, pglob);
			debug_printf("globhack returned %d\n",gr);
		}
	} else {
		gr = globhack(dest->data, flags, pglob);
		debug_printf("globhack returned %d\n",gr);
	}
	if (gr == GLOB_NOSPACE) {
		fprintf(stderr,"out of memory during glob\n");
		exit(1);
	}
	if (gr != 0) { /* GLOB_ABORTED ? */
		fprintf(stderr,"glob(3) error %d\n",gr);
	}
	/* globprint(glob_target); */
	return gr;
}

/* the src parameter allows us to peek forward to a possible &n syntax
 * for file descriptor duplication, e.g., "2>&1".
 * Return code is 0 normally, 1 if a syntax error is detected in src.
 * Resource errors (in xmalloc) cause the process to exit */
static int setup_redirect(struct p_context *ctx, int fd, redir_type style,
	struct in_str *input)
{
	struct child_prog *child=ctx->child;
	struct redir_struct *redir = child->redirects;
	struct redir_struct *last_redir=NULL;

	/* Create a new redir_struct and drop it onto the end of the linked list */
	while(redir) {
		last_redir=redir;
		redir=redir->next;
	}
	redir = xmalloc(sizeof(struct redir_struct));
	redir->next=NULL;
	if (last_redir) {
		last_redir->next=redir;
	} else {
		child->redirects=redir;
	}

	redir->type=style;
	redir->fd= (fd==-1) ? redir_table[style].default_fd : fd ;

	debug_printf("Redirect type %d%s\n", redir->fd, redir_table[style].descrip);

	/* Check for a '2>&1' type redirect */ 
	redir->dup = redirect_dup_num(input);
	if (redir->dup == -2) return 1;  /* syntax error */
	if (redir->dup != -1) {
		/* Erik had a check here that the file descriptor in question
		 * is legit; I postpone that to "run time" */
		debug_printf("Duplicating redirect '%d>&%d'\n", redir->fd, redir->dup);
	} else {
		/* We do _not_ try to open the file that src points to,
		 * since we need to return and let src be expanded first.
		 * Set ctx->pending_redirect, so we know what to do at the
		 * end of the next parsed word.
		 */
		ctx->pending_redirect = redir;
	}
	return 0;
}

struct pipe *new_pipe(void) {
	struct pipe *pi;
	pi = xmalloc(sizeof(struct pipe));
	pi->num_progs = 0;
	pi->progs = NULL;
	pi->next = NULL;
	pi->followup = 0;  /* invalid */
	return pi;
}

static void initialize_context(struct p_context *ctx)
{
	ctx->pipe=NULL;
	ctx->pending_redirect=NULL;
	ctx->child=NULL;
	ctx->list_head=new_pipe();
	ctx->pipe=ctx->list_head;
	ctx->w=RES_NONE;
	ctx->stack=NULL;
	done_command(ctx);   /* creates the memory for working child */
}

/* normal return is 0
 * if a reserved word is found, and processed, return 1
 * should handle if, then, elif, else, fi, for, while, until, do, done.
 * case, function, and select are obnoxious, save those for later.
 */
int reserved_word(o_string *dest, struct p_context *ctx)
{
	struct reserved_combo {
		char *literal;
		int code;
		long flag;
	};
	/* Mostly a list of accepted follow-up reserved words.
	 * FLAG_END means we are done with the sequence, and are ready
	 * to turn the compound list into a command.
	 * FLAG_START means the word must start a new compound list.
	 */
	static struct reserved_combo reserved_list[] = {
		{ "if",    RES_IF,    FLAG_THEN | FLAG_START },
		{ "then",  RES_THEN,  FLAG_ELIF | FLAG_ELSE | FLAG_FI },
		{ "elif",  RES_ELIF,  FLAG_THEN },
		{ "else",  RES_ELSE,  FLAG_FI   },
		{ "fi",    RES_FI,    FLAG_END  },
		{ "for",   RES_FOR,   FLAG_DO   | FLAG_START },
		{ "while", RES_WHILE, FLAG_DO   | FLAG_START },
		{ "until", RES_UNTIL, FLAG_DO   | FLAG_START },
		{ "do",    RES_DO,    FLAG_DONE },
		{ "done",  RES_DONE,  FLAG_END  }
	};
	struct reserved_combo *r;
	for (r=reserved_list;
#define NRES sizeof(reserved_list)/sizeof(struct reserved_combo)
		r<reserved_list+NRES; r++) {
		if (strcmp(dest->data, r->literal) == 0) {
			debug_printf("found reserved word %s, code %d\n",r->literal,r->code);
			if (r->flag & FLAG_START) {
				struct p_context *new = xmalloc(sizeof(struct p_context));
				debug_printf("push stack\n");
				*new = *ctx;   /* physical copy */
				initialize_context(ctx);
				ctx->stack=new;
			} else if ( ctx->w == RES_NONE || ! (ctx->old_flag & (1<<r->code))) {
				syntax();
				ctx->w = RES_SNTX;
				b_reset (dest);
				return 1;
			}
			ctx->w=r->code;
			ctx->old_flag = r->flag;
			if (ctx->old_flag & FLAG_END) {
				struct p_context *old;
				debug_printf("pop stack\n");
				old = ctx->stack;
				old->child->group = ctx->list_head;
				*ctx = *old;   /* physical copy */
				free(old);
				ctx->w=RES_NONE;
			}
			b_reset (dest);
			return 1;
		}
	}
	return 0;
}

/* normal return is 0.
 * Syntax or xglob errors return 1. */
static int done_word(o_string *dest, struct p_context *ctx)
{
	struct child_prog *child=ctx->child;
	glob_t *glob_target;
	int gr, flags = 0;

	debug_printf("done_word: %s %p\n", dest->data, child);
	if (dest->length == 0 && !dest->nonnull) {
		debug_printf("  true null, ignored\n");
		return 0;
	}
	if (ctx->pending_redirect) {
		glob_target = &ctx->pending_redirect->word;
	} else {
		if (child->group) {
			syntax();
			return 1;  /* syntax error, groups and arglists don't mix */
		}
		if (!child->argv) {
			debug_printf("checking %s for reserved-ness\n",dest->data);
			if (reserved_word(dest,ctx)) return ctx->w==RES_SNTX;
		}
		glob_target = &child->glob_result;
 		if (child->argv) flags |= GLOB_APPEND;
	}
	gr = xglob(dest, flags, glob_target);
	if (gr != 0) return 1;

	b_reset(dest);
	if (ctx->pending_redirect) {
		ctx->pending_redirect=NULL;
		if (glob_target->gl_pathc != 1) {
			fprintf(stderr, "ambiguous redirect\n");
			return 1;
		}
	} else {
		child->argv = glob_target->gl_pathv;
	}
	return 0;
}

/* The only possible error here is out of memory, in which case
 * xmalloc exits. */
static int done_command(struct p_context *ctx)
{
	/* The child is really already in the pipe structure, so
	 * advance the pipe counter and make a new, null child.
	 * Only real trickiness here is that the uncommitted
	 * child structure, to which ctx->child points, is not
	 * counted in pi->num_progs. */
	struct pipe *pi=ctx->pipe;
	struct child_prog *prog=ctx->child;

	if (prog && prog->group == NULL
	         && prog->argv == NULL
	         && prog->redirects == NULL) {
		debug_printf("done_command: skipping null command\n");
		return 0;
	} else if (prog) {
		pi->num_progs++;
		debug_printf("done_command: num_progs incremented to %d\n",pi->num_progs);
	} else {
		debug_printf("done_command: initializing\n");
	}
	pi->progs = xrealloc(pi->progs, sizeof(*pi->progs) * (pi->num_progs+1));

	prog = pi->progs + pi->num_progs;
	prog->redirects = NULL;
	prog->argv = NULL;
	prog->is_stopped = 0;
	prog->group = NULL;
	prog->glob_result.gl_pathv = NULL;
	prog->family = pi;

	ctx->child=prog;
	/* but ctx->pipe and ctx->list_head remain unchanged */
	return 0;
}

static int done_pipe(struct p_context *ctx, pipe_style type)
{
	struct pipe *new_p;
	done_command(ctx);  /* implicit closure of previous command */
	debug_printf("done_pipe, type %d\n", type);
	ctx->pipe->followup = type;
	ctx->pipe->r_mode = ctx->w;
	new_p=new_pipe();
	ctx->pipe->next = new_p;
	ctx->pipe = new_p;
	ctx->child = NULL;
	done_command(ctx);  /* set up new pipe to accept commands */
	return 0;
}

/* peek ahead in the in_str to find out if we have a "&n" construct,
 * as in "2>&1", that represents duplicating a file descriptor.
 * returns either -2 (syntax error), -1 (no &), or the number found.
 */
static int redirect_dup_num(struct in_str *input)
{
	int ch, d=0, ok=0;
	ch = b_peek(input);
	if (ch != '&') return -1;

	b_getch(input);  /* get the & */
	while (ch=b_peek(input),isdigit(ch)) {
		d = d*10+(ch-'0');
		ok=1;
		b_getch(input);
	}
	if (ok) return d;

	fprintf(stderr, "ambiguous redirect\n");
	return -2;
}

/* If a redirect is immediately preceded by a number, that number is
 * supposed to tell which file descriptor to redirect.  This routine
 * looks for such preceding numbers.  In an ideal world this routine
 * needs to handle all the following classes of redirects...
 *     echo 2>foo     # redirects fd  2 to file "foo", nothing passed to echo
 *     echo 49>foo    # redirects fd 49 to file "foo", nothing passed to echo
 *     echo -2>foo    # redirects fd  1 to file "foo",    "-2" passed to echo
 *     echo 49x>foo   # redirects fd  1 to file "foo",   "49x" passed to echo
 * A -1 output from this program means no valid number was found, so the
 * caller should use the appropriate default for this redirection.
 */
static int redirect_opt_num(o_string *o)
{
	int num;

	if (o->length==0) return -1;
	for(num=0; num<o->length; num++) {
		if (!isdigit(*(o->data+num))) {
			return -1;
		}
	}
	/* reuse num (and save an int) */
	num=atoi(o->data);
	b_reset(o);
	return num;
}

FILE *generate_stream_from_list(struct pipe *head)
{
	FILE *pf;
#if 1
	int pid, channel[2];
	if (pipe(channel)<0) perror_msg_and_die("pipe");
	pid=fork();
	if (pid<0) {
		perror_msg_and_die("fork");
	} else if (pid==0) {
		close(channel[0]);
		if (channel[1] != 1) {
			dup2(channel[1],1);
			close(channel[1]);
		}
#if 0
#define SURROGATE "surrogate response"
		write(1,SURROGATE,sizeof(SURROGATE));
		exit(run_list(head));
#else
		exit(run_list_real(head));   /* leaks memory */
#endif
	}
	debug_printf("forked child %d\n",pid);
	close(channel[1]);
	pf = fdopen(channel[0],"r");
	debug_printf("pipe on FILE *%p\n",pf);
#else
	run_list_test(head,0);
	pf=popen("echo surrogate response","r");
	debug_printf("started fake pipe on FILE *%p\n",pf);
#endif
	return pf;
}

/* this version hacked for testing purposes */
/* return code is exit status of the process that is run. */
static int process_command_subs(o_string *dest, struct p_context *ctx, struct in_str *input, int subst_end)
{
	int retcode;
	o_string result=NULL_O_STRING;
	struct p_context inner;
	FILE *p;
	struct in_str pipe_str;
	initialize_context(&inner);

	/* recursion to generate command */
	retcode = parse_stream(&result, &inner, input, subst_end);
	if (retcode != 0) return retcode;  /* syntax error or EOF */
	done_word(&result, &inner);
	done_pipe(&inner, PIPE_SEQ);
	b_free(&result);

	p=generate_stream_from_list(inner.list_head);
	if (p==NULL) return 1;
	mark_open(fileno(p));
	setup_file_in_str(&pipe_str, p);

	/* now send results of command back into original context */
	retcode = parse_stream(dest, ctx, &pipe_str, '\0');
	/* XXX In case of a syntax error, should we try to kill the child?
	 * That would be tough to do right, so just read until EOF. */
	if (retcode == 1) {
		while (b_getch(&pipe_str)!=EOF) { /* discard */ };
	}

	debug_printf("done reading from pipe, pclose()ing\n");
	/* This is the step that wait()s for the child.  Should be pretty
	 * safe, since we just read an EOF from its stdout.  We could try
	 * to better, by using wait(), and keeping track of background jobs
	 * at the same time.  That would be a lot of work, and contrary
	 * to the KISS philosophy of this program. */
	mark_closed(fileno(p));
	retcode=pclose(p);
	debug_printf("pclosed, retcode=%d\n",retcode);
	/* XXX this process fails to trim a single trailing newline */
	return retcode;
}

static int parse_group(o_string *dest, struct p_context *ctx,
	struct in_str *input, int ch)
{
	int rcode, endch=0;
	struct p_context sub;
	struct child_prog *child = ctx->child;
	if (child->argv) {
		syntax();
		return 1;  /* syntax error, groups and arglists don't mix */
	}
	initialize_context(&sub);
	switch(ch) {
		case '(': endch=')'; child->subshell=1; break;
		case '{': endch='}'; break;
		default: syntax();   /* really logic error */
	}
	rcode=parse_stream(dest,&sub,input,endch);
	done_word(dest,&sub); /* finish off the final word in the subcontext */
	done_pipe(&sub, PIPE_SEQ);  /* and the final command there, too */
	child->group = sub.list_head;
	return rcode;
	/* child remains "open", available for possible redirects */
}

/* basically useful version until someone wants to get fancier,
 * see the bash man page under "Parameter Expansion" */
static void lookup_param(o_string *dest, struct p_context *ctx, o_string *src)
{
	const char *p=NULL;
	if (src->data) p = getenv(src->data);
	if (p) parse_string(dest, ctx, p);   /* recursion */
	b_free(src);
}

/* return code: 0 for OK, 1 for syntax error */
static int handle_dollar(o_string *dest, struct p_context *ctx, struct in_str *input)
{
	int i, advance=0;
	o_string alt=NULL_O_STRING;
	char sep[]=" ";
	int ch = input->peek(input);  /* first character after the $ */
	debug_printf("handle_dollar: ch=%c\n",ch);
	if (isalpha(ch)) {
		while(ch=b_peek(input),isalnum(ch) || ch=='_') {
			b_getch(input);
			b_addchr(&alt,ch);
		}
		lookup_param(dest, ctx, &alt);
	} else if (isdigit(ch)) {
		i = ch-'0';  /* XXX is $0 special? */
		if (i<global_argc) {
			parse_string(dest, ctx, global_argv[i]); /* recursion */
		}
		advance = 1;
	} else switch (ch) {
		case '$':
			b_adduint(dest,getpid());
			advance = 1;
			break;
		case '!':
			if (last_bg_pid > 0) b_adduint(dest, last_bg_pid);
			advance = 1;
			break;
		case '?':
			b_adduint(dest,last_return_code);
			advance = 1;
			break;
		case '#':
			b_adduint(dest,global_argc ? global_argc-1 : 0);
			advance = 1;
			break;
		case '{':
			b_getch(input);
			/* XXX maybe someone will try to escape the '}' */
			while(ch=b_getch(input),ch!=EOF && ch!='}') {
				b_addchr(&alt,ch);
			}
			if (ch != '}') {
				syntax();
				return 1;
			}
			lookup_param(dest, ctx, &alt);
			break;
		case '(':
			process_command_subs(dest, ctx, input, ')');
			break;
		case '*':
			sep[0]=ifs[0];
			for (i=1; i<global_argc; i++) {
				parse_string(dest, ctx, global_argv[i]);
				if (i+1 < global_argc) parse_string(dest, ctx, sep);
			}
			break;
		case '@':
		case '-':
		case '_':
			/* still unhandled, but should be eventually */
			fprintf(stderr,"unhandled syntax: $%c\n",ch);
			return 1;
			break;
		default:
			b_addqchr(dest,'$',dest->quote);
	}
	/* Eat the character if the flag was set.  If the compiler
	 * is smart enough, we could substitute "b_getch(input);"
	 * for all the "advance = 1;" above, and also end up with
	 * a nice size-optimized program.  Hah!  That'll be the day.
	 */
	if (advance) b_getch(input);
	return 0;
}

int parse_string(o_string *dest, struct p_context *ctx, const char *src)
{
	struct in_str foo;
	setup_string_in_str(&foo, src);
	return parse_stream(dest, ctx, &foo, '\0');
}

/* return code is 0 for normal exit, 1 for syntax error */
int parse_stream(o_string *dest, struct p_context *ctx,
	struct in_str *input, int end_trigger)
{
	unsigned int ch, m;
	int redir_fd;
	redir_type redir_style;
	int next;

	/* Only double-quote state is handled in the state variable dest->quote.
	 * A single-quote triggers a bypass of the main loop until its mate is
	 * found.  When recursing, quote state is passed in via dest->quote. */

	debug_printf("parse_stream, end_trigger=%d\n",end_trigger);
	while ((ch=b_getch(input))!=EOF) {
		m = map[ch];
		next = (ch == '\n') ? 0 : b_peek(input);
		debug_printf("parse_stream: ch=%c (%d) m=%d quote=%d\n",
			ch,ch,m,dest->quote);
		if (m==0 || ((m==1 || m==2) && dest->quote)) {
			b_addqchr(dest, ch, dest->quote);
		} else if (ch == end_trigger && !dest->quote && ctx->w==RES_NONE) {
			debug_printf("leaving parse_stream\n");
			return 0;
		} else if (m==2 && !dest->quote) {  /* IFS */
			done_word(dest, ctx);
			if (ch=='\n') done_pipe(ctx,PIPE_SEQ);
			if (ch == end_trigger && !dest->quote && ctx->w==RES_NONE) {
				debug_printf("leaving parse_stream (stupid duplication)\n");
				return 0;
			}
#if 0
			if (ch=='\n') {
				/* Yahoo!  Time to run with it! */
				done_pipe(ctx,PIPE_SEQ);
				run_list(ctx->list_head);
				initialize_context(ctx);
			}
#endif
		} else switch (ch) {
		case '#':
			if (dest->length == 0 && !dest->quote) {
				while(ch=b_peek(input),ch!=EOF && ch!='\n') { b_getch(input); }
			} else {
				b_addqchr(dest, ch, dest->quote);
			}
			break;
		case '\\':
			if (next == EOF) {
				syntax();
				return 1;
			}
			b_addqchr(dest, '\\', dest->quote);
			b_addqchr(dest, b_getch(input), dest->quote);
			break;
		case '$':
			if (handle_dollar(dest, ctx, input)!=0) return 1;
			break;
		case '\'':
			dest->nonnull = 1;
			while(ch=b_getch(input),ch!=EOF && ch!='\'') {
				b_addchr(dest,ch);
			}
			if (ch==EOF) {
				syntax();
				return 1;
			}
			break;
		case '"':
			dest->nonnull = 1;
			dest->quote = !dest->quote;
			break;
		case '`':
			process_command_subs(dest, ctx, input, '`');
			break;
		case '>':
			redir_fd = redirect_opt_num(dest);
			done_word(dest, ctx);
			redir_style=REDIRECT_OVERWRITE;
			if (next == '>') {
				redir_style=REDIRECT_APPEND;
				b_getch(input);
			} else if (next == '(') {
				syntax();   /* until we support >(list) Process Substitution */
				return 1;
			}
			setup_redirect(ctx, redir_fd, redir_style, input);
			break;
		case '<':
			redir_fd = redirect_opt_num(dest);
			done_word(dest, ctx);
			redir_style=REDIRECT_INPUT;
			if (next == '<') {
				redir_style=REDIRECT_HEREIS;
				b_getch(input);
			} else if (next == '>') {
				redir_style=REDIRECT_IO;
				b_getch(input);
			} else if (next == '(') {
				syntax();   /* until we support <(list) Process Substitution */
				return 1;
			}
			setup_redirect(ctx, redir_fd, redir_style, input);
			break;
		case ';':
			done_word(dest, ctx);
			done_pipe(ctx,PIPE_SEQ);
			break;
		case '&':
			done_word(dest, ctx);
			if (next=='&') {
				b_getch(input);
				done_pipe(ctx,PIPE_AND);
			} else {
				done_pipe(ctx,PIPE_BG);
			}
			break;
		case '|':
			done_word(dest, ctx);
			if (next=='|') {
				b_getch(input);
				done_pipe(ctx,PIPE_OR);
			} else {
				/* we could pick up a file descriptor choice here
				 * with redirect_opt_num(), but bash doesn't do it.
				 * "echo foo 2| cat" yields "foo 2". */
				done_command(ctx);
			}
			break;
		case '(':
		case '{':
			if (parse_group(dest, ctx, input, ch)!=0) return 1;
			break;
		case ')':
		case '}':
			syntax();   /* Proper use of this character caught by end_trigger */
			return 1;
			break;
		default:
			syntax();   /* this is really an internal logic error */
			return 1;
		}
	}
	/* complain if quote?  No, maybe we just finished a command substitution
	 * that was quoted.  Example:
	 * $ echo "`cat foo` plus more" 
	 * and we just got the EOF generated by the subshell that ran "cat foo"
	 * The only real complaint is if we got an EOF when end_trigger != '\0',
	 * that is, we were really supposed to get end_trigger, and never got
	 * one before the EOF.  Can't use the standard "syntax error" return code,
	 * so that parse_stream_outer can distinguish the EOF and exit smoothly. */
	if (end_trigger != '\0') return -1;
	return 0;
}

void mapset(const unsigned char *set, int code)
{
	const unsigned char *s;
	for (s=set; *s; s++) map[*s] = code;
}

void update_ifs_map(void)
{
	/* char *ifs and char map[256] are both globals. */
	ifs = getenv("IFS");
	if (ifs == NULL) ifs=" \t\n";
	/* Precompute a list of 'flow through' behavior so it can be treated
	 * quickly up front.  Computation is necessary because of IFS.
	 * Special case handling of IFS == " \t\n" is not implemented.
	 * The map[] array only really needs two bits each, and on most machines
	 * that would be faster because of the reduced L1 cache footprint.
	 */
	memset(map,0,256);        /* most characters flow through always */
	mapset("\\$'\"`", 3);     /* never flow through */
	mapset("<>;&|(){}#", 1);  /* flow through if quoted */
	mapset(ifs, 2);           /* also flow through if quoted */
}

/* most recursion does not come through here, the exeception is
 * from builtin_source() */
int parse_stream_outer(struct in_str *inp)
{

	struct p_context ctx;
	o_string temp=NULL_O_STRING;
	int rcode;
	do {
		initialize_context(&ctx);
		update_ifs_map();
		inp->promptmode=1;
		rcode = parse_stream(&temp, &ctx, inp, '\n');
		done_word(&temp, &ctx);
		done_pipe(&ctx,PIPE_SEQ);
		run_list(ctx.list_head);
	} while (rcode != -1);   /* loop on syntax errors, return on EOF */
	return 0;
}

static int parse_string_outer(const char *s)
{
	struct in_str input;
	setup_string_in_str(&input, s);
	return parse_stream_outer(&input);
}

static int parse_file_outer(FILE *f)
{
	int rcode;
	struct in_str input;
	setup_file_in_str(&input, f);
	rcode = parse_stream_outer(&input);
	return rcode;
}

int shell_main(int argc, char **argv)
{
	int opt;
	FILE *input;

	/* XXX what should these be while sourcing /etc/profile? */
	global_argc = argc;
	global_argv = argv;

	if (argv[0] && argv[0][0] == '-') {
		debug_printf("\nsourcing /etc/profile\n");
		input = xfopen("/etc/profile", "r");
		mark_open(fileno(input));
		parse_file_outer(input);
		mark_closed(fileno(input));
		fclose(input);
	}
	input=stdin;
	
	/* initialize the cwd -- this is never freed...*/
	cwd = xgetcwd(0);
#ifdef BB_FEATURE_COMMAND_EDITING
	cmdedit_set_initial_prompt();
#else
	PS1 = NULL;
#endif
	
	while ((opt = getopt(argc, argv, "c:xif")) > 0) {
		switch (opt) {
			case 'c':
				{
					global_argv = argv+optind;
					global_argc = argc-optind;
					opt = parse_string_outer(optarg);
					exit(opt);
				}
				break;
			case 'i':
				interactive++;
				break;
			case 'f':
				fake_mode++;
				break;
			default:
				fprintf(stderr, "Usage: sh [FILE]...\n"
						"   or: sh -c command [args]...\n\n");
				exit(EXIT_FAILURE);
		}
	}
	/* A shell is interactive if the `-i' flag was given, or if all of
	 * the following conditions are met:
	 *	  no -c command
	 *    no arguments remaining or the -s flag given
	 *    standard input is a terminal
	 *    standard output is a terminal
	 *    Refer to Posix.2, the description of the `sh' utility. */
	if (argv[optind]==NULL && input==stdin &&
			isatty(fileno(stdin)) && isatty(fileno(stdout))) {
		interactive++;
	}
	
	if (interactive) {
		/* Looks like they want an interactive shell */
		fprintf(stdout, "\nhush -- the humble shell v0.01 (testing)\n\n");
		exit(parse_file_outer(stdin));
	}
	debug_printf("\ninteractive=%d\n", interactive);

	debug_printf("\nrunning script '%s'\n", argv[optind]);
	global_argv = argv+optind;
	global_argc = argc-optind;
	input = xfopen(argv[optind], "r");
	opt = parse_file_outer(input);

#ifdef BB_FEATURE_CLEAN_UP
	fclose(input.file);
#endif

	return(opt);
}