aboutsummaryrefslogtreecommitdiff
path: root/toys/pending/sh.c
blob: 959330f51c5f210a23778ad0cb454c2b695482fc (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
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
/* sh.c - toybox shell
 *
 * Copyright 2006 Rob Landley <rob@landley.net>
 *
 * The POSIX-2008/SUSv4 spec for this is at:
 * http://opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html
 * and http://opengroup.org/onlinepubs/9699919799/utilities/sh.html
 *
 * The first link describes the following shell builtins:
 *
 *   break : continue exit
 *   . eval exec export readonly return set shift times trap unset
 *
 * The second link (the utilities directory) also contains specs for the
 * following shell builtins:
 *
 *   cd ulimit umask
 *   alias bg command fc fg getopts hash jobs kill read type unalias wait
 *
 * Things like the bash man page are good to read too.
 *
 * deviations from posix: don't care about $LANG or $LC_ALL

 * TODO: test that $PS1 color changes work without stupid \[ \] hack
 * TODO: Handle embedded NUL bytes in the command line? (When/how?)

 * builtins: alias bg command fc fg getopts jobs newgrp read umask unalias wait
 *           disown umask suspend source pushd popd dirs logout times trap
 *           unset local export readonly set : . let history declare
 * "special" builtins: break continue eval exec return shift
 * builtins with extra shell behavior: kill pwd time test

 * | & ; < > ( ) $ ` \ " ' <space> <tab> <newline>
 * * ? [ # ~ = %
 * ! { } case do done elif else esac fi for if in then until while
 * [[ ]] function select

 * label:
 * TODO: test exit from "trap EXIT" doesn't recurse
 * TODO: ! history expansion
 * TODO: getuid() vs geteuid()
 *
 * bash man page:
 * control operators || & && ; ;; ;& ;;& ( ) | |& <newline>
 * reserved words
 *   ! case  coproc  do done elif else esac fi for  function  if  in  select
 *   then until while { } time [[ ]]

USE_SH(NEWTOY(cd, ">1LP[-LP]", TOYFLAG_NOFORK))
USE_SH(NEWTOY(eval, 0, TOYFLAG_NOFORK))
USE_SH(NEWTOY(exec, "cla:", TOYFLAG_NOFORK))
USE_SH(NEWTOY(exit, 0, TOYFLAG_NOFORK))
USE_SH(NEWTOY(export, "np", TOYFLAG_NOFORK))
USE_SH(NEWTOY(unset, "fvn", TOYFLAG_NOFORK))

USE_SH(NEWTOY(sh, "(noediting)(noprofile)(norc)sc:i", TOYFLAG_BIN))
USE_SH(OLDTOY(toysh, sh, TOYFLAG_BIN))
USE_SH(OLDTOY(bash, sh, TOYFLAG_BIN))
// Login lies in argv[0], so add some aliases to catch that
USE_SH(OLDTOY(-sh, sh, 0))
USE_SH(OLDTOY(-toysh, sh, 0))
USE_SH(OLDTOY(-bash, sh, 0))

config SH
  bool "sh (toysh)"
  default n
  help
    usage: sh [-c command] [script]

    Command shell.  Runs a shell script, or reads input interactively
    and responds to it.

    -c	command line to execute
    -i	interactive mode (default when STDIN is a tty)

# These are here for the help text, they're not selectable and control nothing
config CD
  bool
  default n
  depends on SH
  help
    usage: cd [-PL] [path]

    Change current directory.  With no arguments, go $HOME.

    -P	Physical path: resolve symlinks in path
    -L	Local path: .. trims directories off $PWD (default)

config EXIT
  bool
  default n
  depends on SH
  help
    usage: exit [status]

    Exit shell.  If no return value supplied on command line, use value
    of most recent command, or 0 if none.

config UNSET
  bool
  default n
  depends on SH
  help
    usage: unset [-fvn] NAME...

    -f	NAME is a function
    -v	NAME is a variable
    -n	dereference NAME and unset that

config EVAL
  bool
  default n
  depends on SH
  help
    usage: eval COMMAND...

    Execute (combined) arguments as a shell command.

config EXEC
  bool
  default n
  depends on SH
  help
    usage: exec [-cl] [-a NAME] COMMAND...

    -a	set argv[0] to NAME
    -c	clear environment
    -l	prepend - to argv[0]

config EXPORT
  bool
  default n
  depends on SH
  help
    usage: export [-n] [NAME[=VALUE]...]

    Make variables available to child processes. NAME exports existing local
    variable(s), NAME=VALUE sets and exports.

    -n	Unexport. Turn listed variable(s) into local variables.

    With no arguments list exported variables/attributes as "declare" statements.
*/

#define FOR_sh
#include "toys.h"

GLOBALS(
  union {
    struct {
      char *c;
    } sh;
    struct {
      char *a;
    } exec;
  };

  // keep lineno here, we use it to work around a compiler bug
  long lineno;
  char *ifs;
  struct double_list functions;
  unsigned options, jobcnt;
  int hfd, pid, varlen, cdcount;
  unsigned long long SECONDS;

  struct sh_vars {
    long flags;
    char *str;
  } *vars;

  // Running jobs for job control.
  struct sh_job {
    struct sh_job *next, *prev;
    unsigned jobno;

    // Every pipeline has at least one set of arguments or it's Not A Thing
    struct sh_arg {
      char **v;
      int c;
    } pipeline;

    // null terminated array of running processes in pipeline
    struct sh_process {
      struct sh_process *next, *prev;
      struct arg_list *delete;   // expanded strings
      // undo redirects, a=b at start, child PID, exit status, has !
      int *urd, envlen, pid, exit, not;
      struct sh_arg arg;
    } *procs, *proc;
  } *jobs, *job;

  struct sh_process *pp;
  struct sh_arg *arg;
)

// Can't yet avoid this prototype. Fundamental problem is $($($(blah))) nests,
// leading to function loop with run->parse->run
static int sh_run(char *new);

// Pipeline segments
struct sh_pipeline {
  struct sh_pipeline *next, *prev;
  int count, here, type;
  struct sh_arg arg[1];
};

// scratch space (state held between calls). Don't want to make it global yet
// because this could be reentrant.
struct sh_function {
  char *name;
  struct sh_pipeline *pipeline;
  struct double_list *expect;
// TODO: lifetime rules for arg? remember "shift" command.
  struct sh_arg *arg; // arguments to function call
  char *end;
};

#define BUGBUG 0

// call with NULL to just dump FDs
static void dump_state(struct sh_function *sp)
{
  struct sh_pipeline *pl;
  long i;
  int q = 0, fd = open("/proc/self/fd", O_RDONLY);
  DIR *dir = fdopendir(fd);
  char buf[256];

  if (sp && sp->expect) {
    struct double_list *dl;

    for (dl = sp->expect; dl; dl = (dl->next == sp->expect) ? 0 : dl->next)
      dprintf(255, "expecting %s\n", dl->data);
    if (sp->pipeline)
      dprintf(255, "pipeline count=%d here=%d\n", sp->pipeline->prev->count,
        sp->pipeline->prev->here);
  }

  if (sp) for (pl = sp->pipeline; pl ; pl = (pl->next == sp->pipeline) ? 0 : pl->next) {
    for (i = 0; i<pl->arg->c; i++)
      dprintf(255, "arg[%d][%ld]=%s\n", q, i, pl->arg->v[i]);
    if (pl->arg->c<0) dprintf(255, "argc=%d\n", pl->arg->c);
    else dprintf(255, "type=%d term[%d]=%s\n", pl->type, q++, pl->arg->v[pl->arg->c]);
  }

  if (dir) {
    struct dirent *dd;

    while ((dd = readdir(dir))) {
      if (atoi(dd->d_name)!=fd && 0<readlinkat(fd, dd->d_name, buf,sizeof(buf)))
        dprintf(255, "OPEN %d: %s = %s\n", getpid(), dd->d_name, buf);
    }
    closedir(dir);
  }
  close(fd);
}

// ordered for greedy matching, so >&; becomes >& ; not > &;
// making these const means I need to typecast the const away later to
// avoid endless warnings.
static const char *redirectors[] = {"<<<", "<<-", "<<", "<&", "<>", "<", ">>",
  ">&", ">|", ">", "&>>", "&>", 0};

#define SH_NOCLOBBER 1   // set -C

static void syntax_err(char *s)
{
  error_msg("syntax error: %s", s);
  toys.exitval = 2;
}

// append to array with null terminator and realloc as necessary
static void array_add(char ***list, unsigned count, char *data)
{
  if (!(count&31)) *list = xrealloc(*list, sizeof(char *)*(count+33));
  (*list)[count] = data;
  (*list)[count+1] = 0;
}

// add argument to an arg_list
static void add_arg(struct arg_list **list, char *arg)
{
  struct arg_list *al;

  if (!list) return;
  al = xmalloc(sizeof(struct arg_list));
  al->next = *list;
  al->arg = arg;
  *list = al;
}

static void array_add_del(char ***list, unsigned count, char *data,
  struct arg_list **delete)
{
  if (delete) add_arg(delete, data);
  array_add(list, count, data);
}

// return length of valid variable name
static char *varend(char *s)
{
  if (isdigit(*s)) return s;
  while (*s>' ' && (*s=='_' || !ispunct(*s))) s++;

  return s;
}

// Return index of variable within this list
static struct sh_vars *findvar(char *name)
{
  int len = varend(name)-name;
  struct sh_vars *var = TT.vars+TT.varlen;

  if (len) while (var-- != TT.vars) 
    if (!strncmp(var->str, name, len) && var->str[len] == '=') return var;

  return 0;
}

// Append variable to TT.vars, returning *struct. Does not check duplicates.
static struct sh_vars *addvar(char *s)
{
  if (!(TT.varlen&31))
    TT.vars = xrealloc(TT.vars, (TT.varlen+32)*sizeof(*TT.vars));
  TT.vars[TT.varlen].flags = 0;
  TT.vars[TT.varlen].str = s;

  return TT.vars+TT.varlen++;
}

// TODO function to resolve a string into a number for $((1+2)) etc
long long do_math(char *s)
{
  return atoll(s);
}

// Assign one variable from malloced key=val string, returns var struct
// TODO implement remaining types
#define VAR_DICT      256
#define VAR_ARRAY     128
#define VAR_INT       64
#define VAR_TOLOWER   32
#define VAR_TOUPPER   16
#define VAR_NAMEREF   8
#define VAR_GLOBAL    4
#define VAR_READONLY  2
#define VAR_MAGIC     1

// declare -aAilnrux
// ft
static struct sh_vars *setvar(char *s)
{
  int len = varend(s)-s;
  long flags;
  struct sh_vars *var;

  if (s[len] != '=') {
    error_msg("bad setvar %s\n", s);
    free(s);
    return 0;
  }
  if (len == 3 && !memcmp(s, "IFS", 3)) TT.ifs = s+4;

  if (!(var = findvar(s))) return addvar(s);
  flags = var->flags;

  if (flags&VAR_READONLY) {
    error_msg("%.*s: read only", len, s);
    free(s);

    return var;
  } else if (flags&VAR_MAGIC) {
    if (*s == 'S') TT.SECONDS = millitime() - 1000*do_math(s+len-1);
    else if (*s == 'R') srandom(do_math(s+len-1));
  } else if (flags&VAR_GLOBAL) xsetenv(var->str = s, 0);
  else {
    free(var->str);
    var->str = s;
  }
// TODO if (flags&(VAR_TOUPPER|VAR_TOLOWER)) 
// unicode _is stupid enough for upper/lower case to be different utf8 byte
// lengths. example: lowercase of U+0130 (C4 B0) is U+0069 (69)
// TODO VAR_INT
// TODO VAR_ARRAY VAR_DICT

  return var;
}

static struct sh_vars *setvarval(char *name, char *val)
{
  return setvar(xmprintf("%s=%s", name, val));
}

// get value of variable starting at s.
static char *getvar(char *s)
{
  struct sh_vars *var = findvar(s);

  if (!var) return 0;

  if (var->flags & VAR_MAGIC) {
    char c = *var->str;

    if (c == 'S') sprintf(toybuf, "%lld", (millitime()-TT.SECONDS)/1000);
    else if (c == 'R') sprintf(toybuf, "%ld", random()&((1<<16)-1));
    else if (c == 'L') sprintf(toybuf, "%ld", TT.lineno);
    else if (c == 'G') sprintf(toybuf, "TODO: GROUPS");

    return toybuf;
  }

  return varend(var->str)+1;
}

static void unsetvar(char *name)
{
  struct sh_vars *var = findvar(name);
  int ii;

  if (!var) return;
  if (var->flags&VAR_GLOBAL) {
    *varend(var->str) = 0;
    xunsetenv(var->str);
  } else free(var->str);

  ii = var-TT.vars;
  memmove(TT.vars+ii, TT.vars+ii+1, TT.varlen-ii);
}

// malloc declare -x "escaped string"
static char *declarep(struct sh_vars *var)
{
  char *types = "-rgnuliaA", *in = types, flags[16], *out = flags, *ss;
  int len;

  while (*++in) if (var->flags&(1<<(in-types))) *out++ = *in;
  if (in == types) *out++ = *types;
  *out = 0;
  len = out-flags;

  for (in = types = varend(var->str); *in; in++) len += !!strchr("$\"\\`", *in);
  len += in-types;
  ss = xmalloc(len+13);

  out = ss + sprintf(ss, "declare -%s \"", out);
  while (types) {
    if (strchr("$\"\\`", *in)) *out++ = '\\';
    *out++ = *types++;
  }
  *out++ = '"';
  *out = 0;
 
  return ss; 
}

// return length of match found at this point (try is null terminated array)
static int anystart(char *s, char **try)
{
  char *ss = s;

  while (*try) if (strstart(&s, *try++)) return s-ss;

  return 0;
}

// does this entire string match one of the strings in try[]
static int anystr(char *s, char **try)
{
  while (*try) if (!strcmp(s, *try++)) return 1;

  return 0;
}

// return length of valid prefix that could go before redirect
static int redir_prefix(char *word)
{
  char *s = word;

  if (*s == '{') {
    if (*(s = varend(s+1)) == '}' && s != word+1) s++;
    else s = word;
  } else while (isdigit(*s)) s++;

  return s-word;
}

// parse next word from command line. Returns end, or 0 if need continuation
// caller eats leading spaces. early = skip one quote block (or return start)
static char *parse_word(char *start, int early)
{
  int i, quote = 0, q, qc = 0;
  char *end = start, *s;

  // Things we should only return at the _start_ of a word

  if (strstart(&end, "<(") || strstart(&end, ">(")) toybuf[quote++]=')';

  // Redirections. 123<<file- parses as 2 args: "123<<" "file-".
  s = end + redir_prefix(end);
  if ((i = anystart(s, (void *)redirectors))) return s+i;

  // (( is a special quote at the start of a word
  if (strstart(&end, "((")) toybuf[quote++] = 254;

  // find end of this word
  while (*end) {
    i = 0;

    // barf if we're near overloading quote stack (nesting ridiculously deep)
    if (quote>4000) {
      syntax_err("tilt");
      return (void *)1;
    }

    // Handle quote contexts
    if ((q = quote ? toybuf[quote-1] : 0)) {

      // when waiting for parentheses, they nest
      if ((q == ')' || q >= 254) && (*end == '(' || *end == ')')) {
        if (*end == '(') qc++;
        else if (qc) qc--;
        else if (q >= 254) {
          // (( can end with )) or retroactively become two (( if we hit one )
          if (strstart(&end, "))")) quote--;
          else if (q == 254) return start+1;
          else if (q == 255) toybuf[quote-1] = ')';
        } else if (*end == ')') quote--;
        end++;

      // end quote?
      } else if (*end == q) quote--, end++;

      // single quote claims everything
      else if (q == '\'') end++;
      else i++;

      // loop if we already handled a symbol and aren't stopping early
      if (early && !quote) return end;
      if (!i) continue;
    } else {
      // Things that only matter when unquoted

      if (isspace(*end)) break;
      if (*end == ')') return end+(start==end);

      // Flow control characters that end pipeline segments
      s = end + anystart(end, (char *[]){";;&", ";;", ";&", ";", "||",
        "|&", "|", "&&", "&", "(", ")", 0});
      if (s != end) return (end == start) ? s : end;
    }

    // Things the same unquoted or in most non-single-quote contexts

    // start new quote context?
    if (strchr("\"'`", *end)) toybuf[quote++] = *end++;

    // backslash escapes
    else if (*end == '\\') {
      if (!end[1] || (end[1]=='\n' && !end[2])) return 0;
      end += 2;
    } else if (*end == '$' && -1 != (i = stridx("({[", end[1]))) {
      end++;
      if (strstart(&end, "((")) toybuf[quote++] = 255;
      else {
        toybuf[quote++] = ")}]"[i];
        end++;
      }
    }
    if (early && !quote) return end;
    end++;
  }

  return quote ? 0 : end;
}

// Return next available high (>=10) file descriptor
static int next_hfd()
{
  int hfd;

  for (; TT.hfd<=99999; TT.hfd++) if (-1 == fcntl(TT.hfd, F_GETFL)) break;
  hfd = TT.hfd;
  if (TT.hfd > 99999) {
    hfd = -1;
    if (!errno) errno = EMFILE;
  }

  return hfd;
}

// Perform a redirect, saving displaced filehandle to a high (>10) fd
// rd is an int array: [0] = count, followed by from/to pairs to restore later.
// If from >= 0 dup from->to after saving to. If from == -1 just save to.
// if from == -2 schedule "to" to be closed by unredirect.
static int save_redirect(int **rd, int from, int to)
{
  int cnt, hfd, *rr;

  if (from == to) return 0;
  // save displaced to, copying to high (>=10) file descriptor to undo later
  // except if we're saving to environment variable instead (don't undo that)
  if (from>-2) {
    if ((hfd = next_hfd())==-1) return 1;
    if (hfd != dup2(to, hfd)) hfd = -1;
    else fcntl(hfd, F_SETFD, FD_CLOEXEC);
if (BUGBUG) dprintf(255, "%d redir from=%d to=%d hfd=%d\n", getpid(), from, to, hfd);
    // dup "to"
    if (from >= 0 && to != dup2(from, to)) {
      if (hfd >= 0) close(hfd);

      return 1;
    }
  } else {
if (BUGBUG) dprintf(255, "%d schedule close %d\n", getpid(), to);
    hfd = to;
    to = -1;
  }

  // Append undo information to redirect list so we can restore saved hfd later.
  if (!((cnt = *rd ? **rd : 0)&31)) *rd = xrealloc(*rd, (cnt+33)*2*sizeof(int));
  *(rr = *rd) = ++cnt;
  rr[2*cnt-1] = hfd;
  rr[2*cnt] = to;

  return 0;
}

// TODO: waitpid(WNOHANG) to clean up zombies and catch background& ending
static void subshell_callback(void)
{
  char *s;

  xsetenv(s = xmprintf("@%d,%d=", getpid(), getppid()), 0);
  s[strlen(s)-1] = 0;
  xsetenv(xmprintf("$=%d", TT.pid), 0);
// TODO: test $$ in (nommu)
}

// TODO check every caller of run_subshell for error, or syntax_error() here
// from pipe() failure

// Pass environment and command string to child shell, return PID of child
static int run_subshell(char *str, int len)
{
  pid_t pid;

if (BUGBUG) dprintf(255, "run_subshell %.*s\n", len, str);
  // The with-mmu path is significantly faster.
  if (CFG_TOYBOX_FORK) {
    char *s;

    if ((pid = fork())<0) perror_msg("fork");
    else if (!pid) {
      s = xstrndup(str, len);
      sh_run(s);
      free(s);
      _exit(toys.exitval);
    }

  // On nommu vfork, exec /proc/self/exe, and pipe state data to ourselves.
  } else {
    int pipes[2], i;

    // open pipe to child
    if (pipe(pipes) || 254 != dup2(pipes[0], 254)) return 1;
    close(pipes[0]);
    fcntl(pipes[1], F_SETFD, FD_CLOEXEC);

    // vfork child
    pid = xpopen_setup(0, 0, subshell_callback);

    // free entries added to end of environment by callback (shared heap)
    for (i = 0; environ[i]; i++) {
      if (!ispunct(environ[i][0])) continue;
      free(environ[i]);
      environ[i] = 0;
    }

    // marshall data to child
    close(254);
    for (i = 0; i<TT.varlen; i++) {
      char *s;

      if (TT.vars[i].flags&VAR_GLOBAL) continue;
      dprintf(pipes[1], "%s\n", s = declarep(TT.vars+i));
      free(s);
    }
    dprintf(pipes[1], "%.*s\n", len, str);
    close(pipes[1]);
  }

  return pid;
}

// restore displaced filehandles, closing high filehandles they were copied to
static void unredirect(int *urd)
{
  int *rr = urd+1, i;

  if (!urd) return;

  for (i = 0; i<*urd; i++, rr += 2) {
if (BUGBUG) dprintf(255, "%d urd %d %d\n", getpid(), rr[0], rr[1]);
    if (rr[0] != -1) {
      // No idea what to do about fd exhaustion here, so Steinbach's Guideline.
      dup2(rr[0], rr[1]);
      close(rr[0]);
    }
  }
  free(urd);
}

// Call subshell with either stdin/stdout redirected, return other end of pipe
static int pipe_subshell(char *s, int len, int out)
{
  int pipes[2], *uu = 0, in = !out;

  // Grab subshell data
  if (pipe(pipes)) {
    perror_msg("%.*s", len, s);

    return -1;
  }

  // Perform input or output redirect and launch process (ignoring errors)
  save_redirect(&uu, pipes[in], in);
  close(pipes[in]);
  run_subshell(s, len);
  unredirect(uu);

  return pipes[out];
}

// utf8 strchr: return wide char matched at wc from chrs, or 0 if not matched
// if len, save length of wc
static int utf8chr(char *wc, char *chrs, int *len)
{
  wchar_t wc1, wc2;
  int ll;

  if (len) *len = 1;
  if (!*wc) return 0;
  if (0<(ll = utf8towc(&wc1, wc, 99))) {
    if (len) *len = ll;
    while (*chrs) {
      if(1>(ll = utf8towc(&wc2, chrs, 99))) chrs++;
      else {
        if (wc1 == wc2) return wc1;
        chrs += ll;
      }
    }
  }

  return 0;
}

// find utf8 characters in utf string
// if c return first char in chrs or null terminator (ala strcspn)
// else return first char not in chars (ala strspn)
static char *utf8spnc(char *str, char *chrs, int c)
{
  int ll, len;

  while (*str) {
    ll = utf8chr(str, chrs, &len);
    if (c ? ll : !ll) break;
    str += len;
  }

  return str;
}

// glue together argument list with separator, plus pre/post sections
static char *merge_args(char *pre, int argc, char *argv[], char *sep,
  int *len, char *post)
{
  int prlen = strlen(pre), polen = strlen(post)+1, jj = 1, kk = 0;
  char *s, *ss;

  while (jj<argc) kk += *len + strlen(argv[jj++]);
  s = ss = xmalloc(prlen+kk+polen);
  memcpy(s, pre, prlen);
  s += prlen;
  for (jj = 1; jj<argc; jj++) s += sprintf(s, "%s%s", argv[jj], sep);
  if (jj != 1) s -= *len;
  *len = s-ss;
  memcpy(s, post, polen);

  return ss;
}


#define NO_PATH  (1<<0)    // path expansion (wildcards)
#define NO_SPLIT (1<<1)    // word splitting
#define NO_BRACE (1<<2)    // {brace,expansion}
#define NO_TILDE (1<<3)    // ~username/path
#define NO_QUOTE (1<<4)    // quote removal
#define FORCE_COPY (1<<31) // don't keep original, copy even if not modified
// TODO: parameter/variable $(command) $((math)) split pathglob
// TODO: ${name:?error} causes an error/abort here (syntax_err longjmp?)
// TODO: $1 $@ $* need args marshalled down here: function+structure?
// arg = append to this
// str = string to expand
// flags = type of expansions (not) to do
// delete = append new allocations to this so they can be freed later
// TODO: at_args: $1 $2 $3 $* $@
static void expand_arg_nobrace(struct sh_arg *arg, char *str, unsigned flags,
  struct arg_list **delete)
{
  char cc, qq = 0, *old = str, *new = str, *s, *ss, *ifs = 0, *del = 0;
  int at = 0, ii = 0, dd, jj, kk, ll, oo = 0;

if (BUGBUG) dprintf(255, "expand %s\n", str);

// TODO ls -l /proc/$$/fd

  // Tilde expansion
  if (!(flags&NO_TILDE) && *str == '~') {
    struct passwd *pw = 0;

    ss = 0;
    while (str[ii] && str[ii]!=':' && str[ii]!='/') ii++;
    if (ii==1) {
      if (!(ss = getvar("HOME")) || !*ss) pw = bufgetpwuid(getuid());
    } else {
      // TODO bufgetpwnam
      pw = getpwnam(s = xstrndup(str+1, ii-1));
      free(s);
    }
    if (pw) {
      ss = pw->pw_dir;
      if (!ss || !*ss) ss = "/";
    }
    if (ss) {
      oo = strlen(ss);
      s = xmprintf("%s%s", ss, str+ii);
      if (old != new) free(new);
      new = s;
    }
  }

  // parameter/variable expansion, and dequoting

  for (; (cc = str[ii++]); old!=new && (new[oo] = 0)) {

    // skip literal chars
    if (!strchr("$'`\\\"", cc)) {
      if (old != new) new[oo++] = cc;
      continue;
    }

    // allocate snapshot if we just started modifying
    if (old == new) {
      new = xstrdup(new);
      new[oo = ii-1] = 0;
    }

    // handle different types of escapes
    if (cc == '\\') new[oo++] = str[ii] ? str[ii++] : cc;
    else if (cc == '"') qq++;
    else if (cc == '\'') {
      if (qq&1) new[oo++] = cc;
      else {
        qq += 2;
        while ((cc = str[ii++]) != '\'') new[oo++] = cc;
      }
    // both types of subshell work the same, so do $( here not in '$' below
// TODO $((echo hello) | cat) ala $(( becomes $( ( retroactively
    } else if (cc == '`' || (cc == '$' && str[ii] == '(')) {
      off_t pp = 0;

      s = str+ii-1;
      kk = parse_word(s, 1)-s;
      if (*toybuf == 255) {
        s += 3;
        kk -= 5;
dprintf(2, "TODO: do math for %.*s\n", kk, s);
      } else {
        // Run subshell and trim trailing newlines
        s += (jj = 1+(cc == '$'));
        ii += --kk;
        kk -= jj;

        // Special case echo $(<input)
        for (ss = s; isspace(*ss); ss++);
        if (*ss != '<') ss = 0;
        else {
          while (isspace(*++ss));
          if (!(ll = parse_word(ss, 0)-ss)) ss = 0;
          else {
            jj = ll+(ss-s);
            while (isspace(s[jj])) jj++;
            if (jj != kk) ss = 0;
            else {
              jj = xcreate_stdio(ss = xstrndup(ss, ll), O_RDONLY|WARN_ONLY, 0);
              free(ss);
            }
          }
        }

// TODO what does \ in `` mean? What is echo `printf %s \$x` supposed to do?
        if (!ss) jj = pipe_subshell(s, kk, 0);
        if ((ifs = del = readfd(jj, 0, &pp)))
          for (kk = strlen(ifs); kk && ifs[kk-1]=='\n'; ifs[--kk] = 0);
        close(jj);
      }
    } else if (cc == '$') {

// *@#?-$!_0 "Special Paremeters" ($0 not affected by shift)

      if (!(cc = str[ii++])) {
        new[oo++] = cc;
        break;
      } else if (cc == '?') ifs = del = xmprintf("%d", toys.exitval);
      else if (cc == '$') ifs = del = xmprintf("%d", TT.pid);
      else if (cc == '#') ifs = del = xmprintf("%d", TT.arg->c?TT.arg->c-1:0);
      else if (cc == '*' || cc == '@') {
        // If not doing word split, handle here
        if ((qq&1) && cc=='*') {
          char buf[8];
          wchar_t wc;

          new[oo] = 0;
          if (0>(oo = utf8towc(&wc, TT.ifs, 4))) oo = 0;
          memcpy(buf, TT.ifs, oo);
          buf[oo] = 0;
          s = merge_args(new, TT.arg->c, TT.arg->v, buf, &oo, str+ii);
          if (new != old) free(new);
          new = s;

        // otherwise hand off to IFS logic at end of loop.
        } else at = 1;
      } else if(isdigit(cc)) {
        for (kk = 0, ii--; isdigit(cc = str[ii]); ii++) kk = (10*kk)+cc-'0';
        if (kk<TT.arg->c) ifs = TT.arg->v[kk];

      // TODO: ${ $(( $[ $'
//      } else if (cc == '{') {

      // $VARIABLE
      } else {
        s = varend(ss = str+--ii);
        if (!(jj = s-ss)) new[oo++] = '$';
// TODO: $((a=42)) can change var, affect lifetime here
        else ifs = getvar(ss);
        ii += jj;
      }
    }

    // combine before/ifs/after sections, splitting words on $IFS in ifs
    if (ifs || at) {
      if (!at && !*ifs && !qq) continue;

      // when at!=0, loop through argv for "$@". Otherwise process ifs as-is
      do {

        // get next argument, is this last entry, first IFS separator character
        if (at) ifs = TT.arg->v[at++];
        kk = !at || at==TT.arg->c;
        ss = (qq&1) ? ifs+strlen(ifs) : utf8spnc(ifs, TT.ifs, 1);

        // loop within current ifs due to word break
        do {
          // fast path: no new allocation when no prefix, no separator,
          // and either not last entry or no suffix
          if (!oo && !*ss && (!kk || !str[ii])) {
            if (!qq && ss==ifs) break;
            dd = !!del;
            del = 0;
          } else {
            // combine prefix, ifs before separator, and suffix (as appropriate)
            ifs = xmprintf("%.*s%.*s%s", oo, new, ll = ss-ifs, ifs,
                         (jj = (kk && !*ss)) ? str+ii : "");
            if (old != new) free(new);
            new = 0;
            dd = 1;
            if (jj) {
              oo += ll;
              new = ifs;

              break;
            } else oo = 0;

            // combine whitespace separators
            while ((jj = utf8chr(ss, TT.ifs, &ll)) && iswspace(jj)) ss += ll;

            // add argument if quoted, non-blank, or non-whitespace separator
            if (!qq && !*ifs && !*ss) {
              free(ifs);

              continue;
            }
          }

          array_add_del(&arg->v, arg->c++, ifs, dd ? delete : 0);
          qq &= 1;
        } while (*(ifs = ss));
      } while (!kk);

      free(del);
      ifs = del = 0;
      at = 0;
    }
  }

// TODO globbing * ? [

// Word splitting completely eliminating argument when no non-$IFS data left
// wordexp keeps pattern when no matches

// TODO NO_SPLIT cares about IFS, see also trailing \n

// quote removal

  // Record result.
  if (*new || qq) {
    if (old==new && (flags&FORCE_COPY)) new = xstrdup(new);
    array_add_del(&arg->v, arg->c++, new, (old != new) ? delete : 0);
  } else if(old != new) free(new);
}

// expand braces (ala {a,b,c}) and call expand_arg_nobrace() each permutation
static void expand_arg(struct sh_arg *arg, char *old, unsigned flags,
  struct arg_list **delete)
{
  struct brace {
    struct brace *next, *prev, *stack;
    int active, cnt, idx, dots[2], commas[];
  } *bb = 0, *blist = 0, *bstk, *bnext;
  int i, j;
  char *s, *ss;

  // collect brace spans
  if (!(flags&NO_BRACE)) for (i = 0; ; i++) {
    while ((s = parse_word(old+i, 1)) != old+i) i += s-(old+i);
    if (!bb && !old[i]) break;
    if (bb && (!old[i] || old[i] == '}')) {
      bb->active = bb->commas[bb->cnt+1] = i;
      for (bnext = bb; bb && bb->active; bb = (bb==blist)?0:bb->prev);
      if (!old[i] || !bnext->cnt) // discard commaless brace from start/middle
        free(dlist_pop((blist == bnext) ? &blist : &bnext));
    } else if (old[i] == '{') {
      dlist_add_nomalloc((void *)&blist,
        (void *)(bb = xzalloc(sizeof(struct brace)+34*4)));
      bb->commas[0] = i;
    } else if (!bb) continue;
    else if  (bb && old[i] == ',') {
      if (bb->cnt && !(bb->cnt&31)) {
        dlist_lpop(&blist);
        dlist_add_nomalloc((void *)&blist,
          (void *)(bb = xrealloc(bb, sizeof(struct brace)+(bb->cnt+34)*4)));
      }
      bb->commas[++bb->cnt] = i;
    }
  }

// TODO NOSPLIT with braces? (Collate with spaces?)
  // If none, pass on verbatim
  if (!blist) return expand_arg_nobrace(arg, old, flags, delete);

  // enclose entire range in top level brace.
  (bstk = xzalloc(sizeof(struct brace)+8))->commas[1] = strlen(old)+1;
  bstk->commas[0] = -1;

  // loop through each combination
  for (;;) {

    // Brace expansion can't be longer than original string. Keep start to {
    s = ss = xmalloc(bstk->commas[1]);

    // Append output from active braces (in "saved" list)
    for (bb = blist; bb;) {

      // keep prefix and push self onto stack
      if (bstk == bb) bstk = bstk->stack;  // pop self
      i = bstk->commas[bstk->idx]+1;
      if (bstk->commas[bstk->cnt+1]>bb->commas[0])
        s = stpncpy(s, old+i, bb->commas[0]-i);

      // pop sibling
      if (bstk->commas[bstk->cnt+1]<bb->commas[0]) bstk = bstk->stack;
 
      bb->stack = bstk; // push
      bb->active = 1;
      bstk = bnext = bb;

      // skip inactive spans from earlier or later commas
      while ((bnext = (bnext->next==blist) ? 0 : bnext->next)) {
        i = bnext->commas[0];

        // past end of this brace
        if (i>bb->commas[bb->cnt+1]) break;

        // in this brace but not this selection
        if (i<bb->commas[bb->idx] || i>bb->commas[bb->idx+1]) {
          bnext->active = 0;
          bnext->stack = 0;

        // in this selection
        } else break;
      }

      // is next span past this range?
      if (!bnext || bnext->commas[0]>bb->commas[bb->idx+1]) {

        // output uninterrupted span
        i = bb->commas[bstk->idx]+1;
        s = stpncpy(s, old+i, bb->commas[bb->idx+1]-i);

        // While not sibling, output tail and pop
        while (!bnext || bnext->commas[0] > bstk->commas[bstk->cnt+1]) {
          if (!(bb = bstk->stack)) break;
          i = bstk->commas[bstk->cnt+1]+1; // start of span
          j = bb->commas[bb->idx+1]; // enclosing comma span

          while (bnext) {
            if (bnext->commas[0]<j) {
              j = bnext->commas[0];// sibling
              break;
            } else if (bb->commas[bb->cnt+1]>bnext->commas[0])
              bnext = (bnext->next == blist) ? 0 : bnext->next;
            else break;
          }
          s = stpncpy(s, old+i, j-i);

          // if next is sibling but parent _not_ a sibling, don't pop
          if (bnext && bnext->commas[0]<bstk->stack->commas[bstk->stack->cnt+1])
            break;
          bstk = bstk->stack;
        }
      }
      bb = (bnext == blist) ? 0 : bnext;
    }

    // Save result
    add_arg(delete, ss);
    expand_arg_nobrace(arg, ss, flags, delete);

    // increment
    for (bb = blist->prev; bb; bb = (bb == blist) ? 0 : bb->prev) {
      if (!bb->stack) continue;
      else if (++bb->idx > bb->cnt) bb->idx = 0;
      else break;
    }

    // if increment went off left edge, done expanding
    if (!bb) return llist_traverse(blist, free);
  }
}

// Expand exactly one arg, returning NULL if it split.
static char *expand_one_arg(char *new, unsigned flags, struct arg_list **del)
{
  struct sh_arg arg;
  char *s = 0;
  int i;

  memset(&arg, 0, sizeof(arg));
  expand_arg(&arg, new, flags, del);
  if (arg.c == 1) s = *arg.v;
  else if (!del) for (i = 0; i < arg.c; i++) free(arg.v[i]);
  free(arg.v);

  return s;
}

// TODO |&

// turn a parsed pipeline back into a string.
static char *pl2str(struct sh_pipeline *pl)
{
  struct sh_pipeline *end = 0;
  int level = 0, len = 0, i, j;
  char *s, *ss, *sss;

  // measure, then allocate
  for (j = 0; ; j++) for (end = pl; end; end = end->next) {
    if (end->type == 1) level++;
    else if (end->type == 3 && --level<0) break;

    for (i = 0; i<pl->arg->c; i++)
      if (j) ss += sprintf(ss, "%s ", pl->arg->v[i]);
      else len += strlen(pl->arg->v[i])+1;

    sss = pl->arg->v[pl->arg->c];
    if (!sss) sss = ";";
    if (j) ss = stpcpy(ss, sss);
    else len += strlen(sss);

// TODO add HERE documents back in
    if (j) return s;
    s = ss = xmalloc(len+1);
  }
}

// Expand arguments and perform redirections. Return new process object with
// expanded args. This can be called from command or block context.
static struct sh_process *expand_redir(struct sh_arg *arg, int envlen, int *urd)
{
  struct sh_process *pp;
  char *s = s, *ss, *sss, *cv = 0;
  int j, to, from, here = 0;

  TT.hfd = 10;

  pp = xzalloc(sizeof(struct sh_process));
  pp->urd = urd;

  // When we redirect, we copy each displaced filehandle to restore it later.

  // Expand arguments and perform redirections
  for (j = envlen; j<arg->c; j++) {
    int saveclose = 0, bad = 0;

    s = arg->v[j];

    if (!strcmp(s, "!")) {
      pp->not ^= 1;

      continue;
    }

    // Handle <() >() redirectionss
    if ((*s == '<' || *s == '>') && s[1] == '(') {
      int new = pipe_subshell(s+2, strlen(s+2)-1, *s == '>');

      // Grab subshell data
      if (new == -1) {
        pp->exit = 1;

        return pp;
      }
      save_redirect(&pp->urd, -2, new);

      // bash uses /dev/fd/%d which requires /dev/fd to be a symlink to
      // /proc/self/fd so we just produce that directly.
      array_add_del(&pp->arg.v, pp->arg.c++,
        ss = xmprintf("/proc/self/fd/%d", new), &pp->delete);

      continue;
    }

    // Is this a redirect? s = prefix, ss = operator
    ss = s + redir_prefix(arg->v[j]);
    sss = ss + anystart(ss, (void *)redirectors);
    if (ss == sss) {
      // Nope: save/expand argument and loop
      expand_arg(&pp->arg, s, 0, &pp->delete);

      continue;
    } else if (j+1 >= arg->c) {
      // redirect needs one argument
      s = "\\n";
      break;
    }
    sss = arg->v[++j];

    // It's a redirect: for [to]<from s = start of [to], ss = <, sss = from
    if (isdigit(*s) && ss-s>5) break;

    // expand arguments for everything but << and <<-
    if (strncmp(ss, "<<", 2) && ss[2] != '<' &&
      !(sss = expand_one_arg(sss, NO_PATH, &pp->delete)))
    {
      s = sss;
      break; // arg splitting here is an error
    }

    // Parse the [fd] part of [fd]<name
    to = *ss != '<';
    if (isdigit(*s)) to = atoi(s);
    else if (*s == '{') {
      if (*varend(s+1) != '}') break;
      // when we close a filehandle, we _read_ from {var}, not write to it
      if ((!strcmp(ss, "<&") || !strcmp(ss, ">&")) && !strcmp(sss, "-")) {
        if (!(ss = getvar(s+1))) break;
        to = atoi(ss); // TODO trailing garbage?
        if (save_redirect(&pp->urd, -1, to)) break;
        close(to);

        continue;
      // record high file descriptor in {to}<from environment variable
      } else {
        // we don't save this, it goes in the env var and user can close it.
        if (-1 == (to = next_hfd())) break;
        cv = xmprintf("%.*s=%d", (int)(ss-s-2), s+1, to);
      }
    }

    // HERE documents?
    if (!strcmp(ss, "<<<") || !strcmp(ss, "<<-") || !strcmp(ss, "<<")) {
      char *tmp = getvar("TMPDIR");
      int i, len, zap = (ss[2] == '-'), x = !ss[strcspn(ss, "\"'")];

      // store contents in open-but-deleted /tmp file.
      tmp = xmprintf("%s/sh-XXXXXX", tmp ? tmp : "/tmp");
      if ((from = mkstemp(tmp))>=0) {
        if (unlink(tmp)) bad++;

        // write contents to file (if <<< else <<) then lseek back to start
        else if (ss[2] == '<') {
          if (x) sss = expand_one_arg(sss, NO_PATH|NO_SPLIT, 0);
          len = strlen(sss);
          if (len != writeall(from, sss, len)) bad++;
          if (x) free(sss);
        } else {
          struct sh_arg *hh = arg+here++;

          for (i = 0; i<hh->c; i++) {
            ss = hh->v[i];
            sss = 0;
            // expand_parameter, commands, and arithmetic
            if (x) ss = sss = expand_one_arg(ss,
              NO_PATH|NO_SPLIT|NO_BRACE|NO_TILDE|NO_QUOTE, 0);

            while (zap && *ss == '\t') ss++;
            x = writeall(from, ss, len = strlen(ss));
            free(sss);
            if (len != x) break;
          }
          if (i != hh->c) bad++;
        }
        if (!bad && lseek(from, 0, SEEK_SET)) bad++;
        if (bad) close(from);
      } else bad++;
      free(tmp);
      if (bad) break;

    // from is fd<<2 (new fd to dup2() after vfork()) plus
    // 2 if we should close(from>>2) after dup2(from>>2, to),
    // 1 if we should close but dup for nofork recovery (ala <&2-)

    // Handle file descriptor duplication/close (&> &>> <& >& with number or -)
    // These redirect existing fd so nothing to open()
    } else if (*ss == '&' || ss[1] == '&') {

      // is there an explicit fd?
      for (ss = sss; isdigit(*ss); ss++);
      if (ss-sss>5 || (*ss && (*ss != '-' || ss[1]))) {
        if (*ss=='&') ss++;
        saveclose = 4;
        goto notfd;
      }

      from = (ss==sss) ? to : atoi(sss);
      saveclose = 2-(*ss == '-');
    } else {
notfd:
      // Permissions to open external file with: < > >> <& >& <> >| &>> &>
      if (!strcmp(ss, "<>")) from = O_CREAT|O_RDWR;
      else if (strstr(ss, ">>")) from = O_CREAT|O_APPEND|O_WRONLY;
      else {
        from = (*ss == '<') ? O_RDONLY : O_CREAT|O_WRONLY|O_TRUNC;
        if (!strcmp(ss, ">") && (TT.options&SH_NOCLOBBER)) {
          struct stat st;

          // Not _just_ O_EXCL: > /dev/null allowed
          if (stat(sss, &st) || !S_ISREG(st.st_mode)) from |= O_EXCL;
        }
      }

      // we expect /dev/fd/# and /dev/{stdin,stdout,stderr} to be in /dev

// TODO: /dev/{tcp,udp}/host/port

      // Open the file
      if (-1 == (from = xcreate_stdio(sss, from|WARN_ONLY, 0666))) {
        s = 0;

        break;
      }
    }

    // perform redirect, saving displaced "to".
    if (save_redirect(&pp->urd, from, to)) bad++;
    // Do we save displaced "to" in env variable instead of undo list?
    if (cv) {
      --*pp->urd;
      setvar(cv);
      cv = 0;
    }
    if ((saveclose&1) && save_redirect(&pp->urd, -1, from)) bad++;
    if ((saveclose&4) && save_redirect(&pp->urd, from, 2)) bad++;
    if (!(saveclose&2)) close(from);
    if (bad) break;
  }

  // didn't parse everything?
  if (j != arg->c) {
    if (s) syntax_err(s);
    if (!pp->exit) pp->exit = 1;
    free(cv);
  }

  return pp;
}

// Execute a single command
static struct sh_process *run_command(struct sh_arg *arg)
{
  struct sh_process *pp;
  struct toy_list *tl;
  int envlen, j;
  char *s;

if (BUGBUG) dprintf(255, "run_command %s\n", arg->v[0]);

  // Grab leading variable assignments
  for (envlen = 0; envlen<arg->c; envlen++) {
    s = varend(arg->v[envlen]);
    if (s == arg->v[envlen] || *s != '=') break;
  }

  // expand arguments and perform redirects
  pp = expand_redir(arg, envlen, 0);

if (BUGBUG) { int i; dprintf(255, "envlen=%d arg->c=%d run=", envlen, arg->c); for (i=0; i<pp->arg.c; i++) dprintf(255, "'%s' ", pp->arg.v[i]); dprintf(255, "\n"); }
  // perform assignments locally if there's no command
  if (envlen == arg->c) {
    for (j = 0; j<envlen; j++) {
      s = expand_one_arg(arg->v[j], NO_PATH|NO_SPLIT, 0);
      if (s == arg->v[j]) s = xstrdup(s);
      setvar(s);
    }

  // Do nothing if nothing to do
  } else if (pp->exit || !pp->arg.v);
//  else if (!strcmp(*pp->arg.v, "(("))
// TODO: handle ((math)) currently totally broken
// TODO: call functions()
  // Is this command a builtin that should run in this process?
  else if ((tl = toy_find(*pp->arg.v))
    && (tl->flags & (TOYFLAG_NOFORK|TOYFLAG_MAYFORK)))
  {
    sigjmp_buf rebound;
    char temp[j = offsetof(struct toy_context, rebound)];

    // This fakes lots of what toybox_main() does.
    memcpy(&temp, &toys, j);
    memset(&toys, 0, j);

    // If we give the union in TT a name, the compiler complains
    // "declaration does not declare anything", but if we DON'T give it a name
    // it accepts it. So we can't use the union's type name here, and have
    // to offsetof() the first thing _after_ the union to get the size.
    memset(&TT, 0, offsetof(struct sh_data, lineno));

    TT.pp = pp;
    if (!sigsetjmp(rebound, 1)) {
      toys.rebound = &rebound;
      toy_singleinit(tl, pp->arg.v);  // arg.v must be null terminated
      tl->toy_main();
      xflush(0);
    }
    TT.pp = 0;
    toys.rebound = 0;
    pp->exit = toys.exitval;
    if (toys.optargs != toys.argv+1) free(toys.optargs);
    if (toys.old_umask) umask(toys.old_umask);
    memcpy(&toys, &temp, j);
  } else {
    char **env = 0, **old = environ, *ss = 0, *sss;
    int kk = 0, ll, mm = -1;

    // We don't allocate/free any array members, just the array
    if (environ) while (environ[kk]) {
      if (strncmp(environ[kk], "SHLVL=", 6)) mm = kk;
      kk++;
    }
    if (kk) {
      env = xmalloc(sizeof(char *)*(kk+33));
      memcpy(env, environ, sizeof(char *)*(kk+1));
      if (mm != -1) env[mm] = xmprintf("SHLVL=%d", atoi(env[mm]+6)+1);
      environ = env;
    }

    // assign leading environment variables
    for (j = 0; j<envlen; j++) {
      sss = expand_one_arg(arg->v[j], NO_PATH|NO_SPLIT, &pp->delete);
      for (ll = 0; ll<kk; ll++) {
        for (s = sss, ss = env[ll]; *s == *ss && *s != '='; s++, ss++);
        if (*s != '=') continue;
        env[ll] = sss;
        break;
      }
      if (ll == kk) array_add(&environ, kk++, sss);
    }

    if (-1 == (pp->pid = xpopen_both(pp->arg.v, 0)))
      perror_msg("%s: vfork", *pp->arg.v);

    // Restore environment variables
    environ = old;
    if (mm != -1) free(env[mm]);
    free(env);
  }

  // cleanup process
  unredirect(pp->urd);

  return pp;
}

static void free_process(void *ppp)
{
  struct sh_process *pp = ppp;
  llist_traverse(pp->delete, llist_free_arg);
  free(pp);
}

// if then fi for while until select done done case esac break continue return

// Free one pipeline segment.
static void free_pipeline(void *pipeline)
{
  struct sh_pipeline *pl = pipeline;
  int i, j;

  if (pl) for (j=0; j<=pl->count; j++) {
    for (i = 0; i<=pl->arg->c; i++)  free(pl->arg[j].v[i]);
    free(pl->arg[j].v);
  }
  free(pl);
}

// Return end of current block, or NULL if we weren't in block and fell off end.
static struct sh_pipeline *block_end(struct sh_pipeline *pl)
{
  int i = 0;

// TODO: should this be inlined into type 1 processing to set blk->end and
// then everything else use that?

  while (pl) {
    if (pl->type == 1 || pl->type == 'f') i++;
    else if (pl->type == 3) if (--i<1) break;
    pl = pl->next;
  }

  return pl;
}

static void free_function(struct sh_function *sp)
{
  llist_traverse(sp->pipeline, free_pipeline);
  llist_traverse(sp->expect, free);
  memset(sp, 0, sizeof(struct sh_function));
}

// TODO this has to add to a namespace context. Functions within functions...
static struct sh_pipeline *add_function(char *name, struct sh_pipeline *pl)
{
dprintf(2, "stub add_function");

  return block_end(pl->next);
}

// Add a line of shell script to a shell function. Returns 0 if finished,
// 1 to request another line of input (> prompt), -1 for syntax err
static int parse_line(char *line, struct sh_function *sp)
{
  char *start = line, *delete = 0, *end, *last = 0, *s, *ex, done = 0;
  struct sh_pipeline *pl = sp->pipeline ? sp->pipeline->prev : 0;
  struct sh_arg *arg = 0;
  long i;

  // Resume appending to last statement?
  if (pl) {
    arg = pl->arg;

    // Extend/resume quoted block
    if (arg->c<0) {
      delete = start = xmprintf("%s%s", arg->v[arg->c = (-arg->c)-1], start);
      free(arg->v[arg->c]);
      arg->v[arg->c] = 0;

    // is a HERE document in progress?
    } else if (pl->count != pl->here) {
      arg += 1+pl->here;

      // Match unquoted EOF.
      for (s = line, end = arg->v[arg->c]; *s && *end; s++, i++) {
        s += strspn(s, "\\\"'");
        if (*s != *end) break;
      }
      if (!*s && !*end) {
        // Add this line
        array_add(&arg->v, arg->c++, xstrdup(line));
        array_add(&arg->v, arg->c, arg->v[arg->c]);
        arg->c++;
      // EOF hit, end HERE document
      } else {
        arg->v[arg->c] = 0;
        pl->here++;
      }
      start = 0;

    // Nope, new segment
    } else pl = 0;
  }

  // Parse words, assemble argv[] pipelines, check flow control and HERE docs
  if (start) for (;;) {
    ex = sp->expect ? sp->expect->prev->data : 0;

    // Look for << HERE redirections in completed pipeline segment
    if (pl && pl->count == -1) {
      pl->count = 0;
      arg = pl->arg;

      // find arguments of the form [{n}]<<[-] with another one after it
      for (i = 0; i<arg->c; i++) {
        s = arg->v[i] + redir_prefix(arg->v[i]);
// TODO <<< is funky
// argc[] entries removed from main list? Can have more than one?
        if (strcmp(s, "<<") && strcmp(s, "<<-") && strcmp(s, "<<<")) continue;
        if (i+1 == arg->c) goto flush;

        // Add another arg[] to the pipeline segment (removing/readding to list
        // because realloc can move pointer)
        dlist_lpop(&sp->pipeline);
        pl = xrealloc(pl, sizeof(*pl) + ++pl->count*sizeof(struct sh_arg));
        dlist_add_nomalloc((void *)&sp->pipeline, (void *)pl);

        // queue up HERE EOF so input loop asks for more lines.
        arg[pl->count].v = xzalloc(2*sizeof(void *));
        arg[pl->count].v[0] = arg->v[++i];
        arg[pl->count].v[1] = 0;
        arg[pl->count].c = 0;
        if (s[2] == '<') pl->here++; // <<< doesn't load more data
      }
      pl = 0;
    }
    if (done) break;
    s = 0;

    // skip leading whitespace/comment here to know where next word starts
    while (isspace(*start)) ++start;
    if (*start=='#') while (*start && *start != '\n') ++start;

    // Parse next word and detect overflow (too many nested quotes).
    if ((end = parse_word(start, 0)) == (void *)1) goto flush;

if (BUGBUG>1) dprintf(255, "[%.*s]%c", end ? (int)(end-start) : 0, start, pl ? ' ' : '\n');
    // Is this a new pipeline segment?
    if (!pl) {
      pl = xzalloc(sizeof(struct sh_pipeline));
      arg = pl->arg;
      dlist_add_nomalloc((void *)&sp->pipeline, (void *)pl);
    }

    // Do we need to request another line to finish word (find ending quote)?
    if (!end) {
      // Save unparsed bit of this line, we'll need to re-parse it.
      array_add(&arg->v, arg->c++, xstrndup(start, strlen(start)));
      arg->c = -arg->c;
      free(delete);

      return 1;
    }

    // Ok, we have a word. What does it _mean_?

    // Did we hit end of line or ) outside a function declaration?
    // ) is only saved at start of a statement, ends current statement
    if (end == start || (arg->c && *start == ')' && pl->type!='f')) {
      if (!arg->v) array_add(&arg->v, arg->c, 0);

      if (pl->type == 'f' && arg->c<3) {
        s = "function()";
        goto flush;
      }

      // "for" on its own line is an error.
      if (arg->c == 1 && ex && !memcmp(ex, "do\0A", 4)) {
        s = "newline";
        goto flush;
      }

      // don't save blank pipeline segments
      if (!arg->c) free_pipeline(dlist_lpop(&sp->pipeline));

      // stop at EOL, else continue with new pipeline segment for )
      if (end == start) done++;
      pl->count = -1;
      last = 0;

      continue;
    }

    // Save argument (strdup) and check for flow control
    array_add(&arg->v, arg->c, s = xstrndup(start, end-start));
    start = end;

    if (strchr(";|&", *s) && strncmp(s, "&>", 2)) {

      // treat ; as newline so we don't have to check both elsewhere.
      if (!strcmp(s, ";")) {
        arg->v[arg->c] = 0;
        free(s);
        s = 0;
// TODO enforce only one ; allowed between "for i" and in or do.
        if (!arg->c && ex && !memcmp(ex, "do\0C", 4)) continue;

      // ;; and friends only allowed in case statements
      } else if (*s == ';' && (!ex || strcmp(ex, "esac"))) goto flush;
      last = s;

      // flow control without a statement is an error
      if (!arg->c) goto flush;
      pl->count = -1;

      continue;
    } else arg->v[++arg->c] = 0;

    // is a function() in progress?
    if (arg->c>1 && !strcmp(s, "(")) pl->type = 'f';
    if (pl->type=='f') {
      if (arg->c == 2 && strcmp(s, "(")) goto flush;
      if (arg->c == 3) {
        if (strcmp(s, ")")) goto flush;

        // end function segment, expect function body
        pl->count = -1;
        last = 0;
        dlist_add(&sp->expect, "}");
        dlist_add(&sp->expect, 0);
        dlist_add(&sp->expect, "{");

        continue;
      }

    // a for/select must have at least one additional argument on same line
    } else if (ex && !memcmp(ex, "do\0A", 4)) {

      // Sanity check and break the segment
      if (strncmp(s, "((", 2) && strchr(s, '=')) goto flush;
      pl->count = -1;
      sp->expect->prev->data = "do\0C";

      continue;

    // flow control is the first word of a pipeline segment
    } else if (arg->c>1) continue;

    // Do we expect something that _must_ come next? (no multiple statements)
    if (ex) {
      // When waiting for { it must be next symbol, but can be on a new line.
      if (!strcmp(ex, "{")) {
        if (strcmp(s, "{")) goto flush;
        free(arg->v[--arg->c]);  // don't save the {, function starts the block
        free(dlist_lpop(&sp->expect));

        continue;

      // The "test" part of for/select loops can have (at most) one "in" line,
      // for {((;;))|name [in...]} do
      } else if (!memcmp(ex, "do\0C", 4)) {
        if (strcmp(s, "do")) {
          // can only have one "in" line between for/do, but not with for(())
          if (!pl->prev->type) goto flush;
          if (!strncmp(pl->prev->arg->v[1], "((", 2)) goto flush;
          else if (strcmp(s, "in")) goto flush;

          continue;
        }
      }
    }

    // start of a new block?

    // for/select requires variable name on same line, can't break segment yet
    if (!strcmp(s, "for") || !strcmp(s, "select")) {
      if (!pl->type) pl->type = 1;
      dlist_add(&sp->expect, "do\0A");

      continue;
    }

    end = 0;
    if (!strcmp(s, "if")) end = "then";
    else if (!strcmp(s, "while") || !strcmp(s, "until")) end = "do\0B";
    else if (!strcmp(s, "case")) end = "esac";
    else if (!strcmp(s, "{")) end = "}";
    else if (!strcmp(s, "[[")) end = "]]";
    else if (!strcmp(s, "(")) end = ")";

    // Expecting NULL means a statement: I.E. any otherwise unrecognized word
    else if (sp->expect && !ex) {
      free(dlist_lpop(&sp->expect));
      continue;
    } else if (!ex) goto check;

    // Did we start a new statement?
    if (end) {
      pl->type = 1;

      // Only innermost statement needed in { { { echo ;} ;} ;} and such
      if (sp->expect && !sp->expect->prev->data) free(dlist_lpop(&sp->expect));

    // If we got here we expect a specific word to end this block: is this it?
    } else if (!strcmp(s, ex)) {
      // can't "if | then" or "while && do", only ; & or newline works
      if (last && (strcmp(ex, "then") || strcmp(last, "&"))) {
        s = end;
        goto flush;
      }

      free(dlist_lpop(&sp->expect));
      pl->type = anystr(s, (char *[]){"fi", "done", "esac", "}", "]]", ")", 0})
        ? 3 : 2;

      // if it's a multipart block, what comes next?
      if (!strcmp(s, "do")) end = "done";
      else if (!strcmp(s, "then")) end = "fi\0A";

    // fi could have elif, which queues a then.
    } else if (!strcmp(ex, "fi")) {
      if (!strcmp(s, "elif")) {
        free(dlist_lpop(&sp->expect));
        end = "then";
      // catch duplicate else while we're here
      } else if (!strcmp(s, "else")) {
        if (ex[3] != 'A') {
          s = "2 else";
          goto flush;
        }
        free(dlist_lpop(&sp->expect));
        end = "fi\0B";
      }
    }

    // Do we need to queue up the next thing to expect?
    if (end) {
      if (!pl->type) pl->type = 2;
      dlist_add(&sp->expect, end);
      dlist_add(&sp->expect, 0);    // they're all preceded by a statement
      pl->count = -1;
    }

check:
    // syntax error check: these can't be the first word in an unexpected place
    if (!pl->type && anystr(s, (char *[]){"then", "do", "esac", "}", "]]", ")",
        "done", "fi", "elif", "else", 0})) goto flush;
  }
  free(delete);

  // ignore blank and comment lines
  if (!sp->pipeline) return 0;

// TODO <<< has no parsing impact, why play with it here at all?
  // advance past <<< arguments (stored as here documents, but no new input)
  pl = sp->pipeline->prev;
  while (pl->count<pl->here && pl->arg[pl->count].c<0)
    pl->arg[pl->count++].c = 0;

  // return if HERE document pending or more flow control needed to complete
  if (sp->expect) return 1;
  if (sp->pipeline && pl->count != pl->here) return 1;
  if (pl->arg->v[pl->arg->c]) return 1;

  // Don't need more input, can start executing.

  dlist_terminate(sp->pipeline);
  return 0;

flush:
  if (s) syntax_err(s);
  free_function(sp);

  return 0-!!s;
}

/* Flow control statements:

  if/then/elif/else/fi, for select while until/do/done, case/esac,
  {/}, [[/]], (/), function assignment
*/


// wait for every process in a pipeline to end
static int wait_pipeline(struct sh_process *pp)
{
  int rc = 0;

  for (dlist_terminate(pp); pp; pp = pp->next) {
    if (pp->pid) {
      // TODO job control: not xwait, handle EINTR ourselves and check signals
      pp->exit = xwaitpid(pp->pid);
      pp->pid = 0;
    }
    // TODO handle set -o pipefail here
    rc = pp->not ? !pp->exit : pp->exit;
  }

  return rc;
}

// pipe data into and out of this segment, I.E. handle leading and trailing |
static int pipe_segments(char *ctl, int *pipes, int **urd)
{
  unredirect(*urd);
  *urd = 0;

  // Did the previous pipe segment pipe input into us?
  if (*pipes != -1) {
    if (save_redirect(urd, *pipes, 0)) return 1;
    close(*pipes);
    *pipes = -1;
  }

  // are we piping output to the next segment?
  if (ctl && *ctl == '|' && ctl[1] != '|') {
    if (pipe(pipes)) {
      perror_msg("pipe");
// TODO record pipeline rc
// TODO check did not reach end of pipeline after loop
      return 1;
    }
    if (save_redirect(urd, pipes[1], 1)) {
      close(pipes[0]);
      close(pipes[1]);

      return 1;
    }
    if (pipes[1] != 1) close(pipes[1]);
    fcntl(*pipes, F_SETFD, FD_CLOEXEC);
    if (ctl[1] == '&') save_redirect(urd, 1, 2);
  }

  return 0;
}

// Handle && and || traversal in pipeline segments
static struct sh_pipeline *skip_andor(int rc, struct sh_pipeline *pl)
{
  char *ctl = pl->arg->v[pl->arg->c];

  // For && and || skip pipeline segment(s) based on return code
  while (ctl && ((!strcmp(ctl, "&&") && rc) || (!strcmp(ctl, "||") && !rc))) {
    if (!pl->next || pl->next->type == 2 || pl->next->type == 3) break;
    pl = pl->type ? block_end(pl) : pl->next;
    ctl = pl ? pl->arg->v[pl->arg->c] : 0;
  }

  return pl;
}

// run a parsed shell function. Handle flow control blocks and characters,
// setup pipes and block redirection, break/continue, call builtins,
// vfork/exec external commands.
static void run_function(struct sh_pipeline *pl)
{
  struct sh_pipeline *end;
  struct blockstack {
    struct blockstack *next;
    struct sh_pipeline *start, *end;
    struct sh_process *pin;      // processes piping into this block
    int run, loop, *urd, pout;
    struct sh_arg farg;          // for/select arg stack
    struct arg_list *fdelete; // farg's cleanup list
    char *fvar;                  // for/select's iteration variable name
  } *blk = 0, *new;
  struct sh_process *pplist = 0; // processes piping into current level
  int *urd = 0, pipes[2] = {-1, -1};
  long i;

// TODO can't free sh_process delete until ready to dispose else no debug output

  TT.hfd = 10;

  // iterate through pipeline segments
  while (pl) {
    struct sh_arg *arg = pl->arg;
    char *s = *arg->v, *ss = arg->v[1], *ctl = arg->v[arg->c];
if (BUGBUG) dprintf(255, "%d runtype=%d %s %s\n", getpid(), pl->type, s, ctl);
    // Is this an executable segment?
    if (!pl->type) {

      // Skip disabled block
      if (blk && !blk->run) {
        pl = pl->next;
        continue;
      }
      if (pipe_segments(ctl, pipes, &urd)) break;

      // If we just started a new pipeline, implicit parentheses (subshell)

// TODO: "echo | read i" is backgroundable with ctrl-Z despite read = builtin.
//       probably have to inline run_command here to do that? Implicit ()
//       also "X=42 | true; echo $X" doesn't get X.

      // TODO: bash supports "break &" and "break > file". No idea why.

      // Is it a flow control jump? These aren't handled as normal builtins
      // because they move *pl to other pipeline segments which is local here.
      if (!strcmp(s, "break") || !strcmp(s, "continue")) {

        // How many layers to peel off?
        i = ss ? atol(ss) : 0;
        if (i<1) i = 1;
        if (!blk || arg->c>2 || ss[strspn(ss, "0123456789")]) {
          syntax_err(s);
          break;
        }
        i = atol(ss);
        if (!i) i++;
        while (i && blk) {
          if (--i && *s == 'c') {
            pl = blk->start;
            break;
          }
          pl = blk->end;
// TODO collate end_block logic

          // if ending a block, free, cleanup redirects and pop stack.
          llist_traverse(blk->fdelete, free);
          unredirect(blk->urd);
          if (*pipes) close(*pipes);
          *pipes = blk->pout;
          free(llist_pop(&blk));
        }
        if (i) {
          syntax_err("break outside loop");
          break;
        }
        pl = pl->next;
        continue;

      // Parse and run next command
      } else {

// TODO: "echo | read i" is backgroundable with ctrl-Z despite read = builtin.
//       probably have to inline run_command here to do that? Implicit ()
//       also "X=42 | true; echo $X" doesn't get X.
//       I.E. run_subshell() here sometimes? (But when?)

        dlist_add_nomalloc((void *)&pplist, (void *)run_command(arg));
      }

      if (*pipes == -1) {
        toys.exitval = wait_pipeline(pplist);
        llist_traverse(pplist, free_process);
        pplist = 0;
        pl = skip_andor(toys.exitval, pl);
      }

    // Start of flow control block?
    } else if (pl->type == 1) {
      struct sh_process *pp = 0;

      // are we entering this block (rather than looping back to it)?
      if (!blk || blk->start != pl) {

        // If it's a nested block we're not running, skip ahead.
        end = block_end(pl->next);
        if (blk && !blk->run) {
          pl = end;
          if (pl) pl = pl->next;
          continue;
        }

        // If previous piped into this block, save context until block end
        if (pipe_segments(end->arg->v[end->arg->c], pipes, &urd)) break;

        // It's a new block we're running, save context and add it to the stack.
        new = xzalloc(sizeof(*blk));
        new->next = blk;
        blk = new;
        blk->start = pl;
        blk->end = end;
        blk->run = 1;

        // save context until block end
        blk->pout = *pipes;
        blk->urd = urd;
        urd = 0;
        *pipes = -1;

        // Perform redirects listed at end of block
        pp = expand_redir(end->arg, 1, blk->urd);
        blk->urd = pp->urd;
        if (pp->arg.c) {
          syntax_err(*pp->arg.v);
          llist_traverse(pp->delete, free);
          free(pp);
          break;
        }
      }

      // What flow control statement is this?

      // {/} if/then/elif/else/fi, while until/do/done - no special handling

      // for select/do/done
      if (!strcmp(s, "for") || !strcmp(s, "select")) {
        if (blk->loop);
        else if (!strncmp(blk->fvar = ss, "((", 2)) {
          blk->loop = 1;
dprintf(2, "TODO skipped init for((;;)), need math parser\n");
        } else {

          // populate blk->farg with expanded arguments
          if (!pl->next->type) {
            for (i = 1; i<pl->next->arg->c; i++)
              expand_arg(&blk->farg, pl->next->arg->v[i], 0, &blk->fdelete);
          } else expand_arg(&blk->farg, "\"$@\"", 0, &blk->fdelete);
        }
        if (!pl->next->type) pl = pl->next;

// TODO case/esac [[/]] (/) ((/)) function/}

/*
TODO: a | b | c needs subshell for builtins?
        - anything that can produce output
        - echo declare dirs
      (a; b; c) like { } but subshell
      when to auto-exec? ps vs sh -c 'ps' vs sh -c '(ps)'
*/

      // subshell
      } else if (!strcmp(s, "(")) {
        if (!CFG_TOYBOX_FORK) {
          ss = pl2str(pl->next);
          pp->pid = run_subshell(ss, strlen(ss));
          free(ss);
        } else {
          if (!(pp->pid = fork())) {
            run_function(pl->next);
            _exit(toys.exitval);
          }
        }

        dlist_add_nomalloc((void *)&pplist, (void *)pp);
        pl = blk->end->prev;
      }

    // gearshift from block start to block body (end of flow control test)
    } else if (pl->type == 2) {

      // Handle if statement
      if (!strcmp(s, "then")) blk->run = blk->run && !toys.exitval;
      else if (!strcmp(s, "else") || !strcmp(s, "elif")) blk->run = !blk->run;
      else if (!strcmp(s, "do")) {
        ss = *blk->start->arg->v;
        if (!strcmp(ss, "while")) blk->run = blk->run && !toys.exitval;
        else if (!strcmp(ss, "until")) blk->run = blk->run && toys.exitval;
        else if (blk->loop >= blk->farg.c) {
          blk->run = 0;
          pl = block_end(pl);
          continue;
        } else if (!strncmp(blk->fvar, "((", 2)) {
dprintf(2, "TODO skipped running for((;;)), need math parser\n");
        } else setvarval(blk->fvar, blk->farg.v[blk->loop++]);
      }

    // end of block, may have trailing redirections and/or pipe
    } else if (pl->type == 3) {

      // if we end a block we're not in, we started in a block.
      if (!blk) break;

      // repeating block?
      if (blk->run && !strcmp(s, "done")) {
        pl = blk->start;
        continue;
      }

// TODO goto "break" above instead of copying it here?
      // if ending a block, free, cleanup redirects, and pop stack.
      // needing to unredirect(urd) or close(pipes[0]) here would be syntax err
      llist_traverse(blk->fdelete, free);
      unredirect(blk->urd);
      *pipes = blk->pout;
      free(llist_pop(&blk));
    } else if (pl->type == 'f') pl = add_function(s, pl);

    pl = pl->next;
  }

  // did we exit with unfinished stuff?
  if (*pipes != -1) close(*pipes);
  if (pplist) {
    toys.exitval = wait_pipeline(pplist);
    llist_traverse(pplist, free_process);
  }
  unredirect(urd);

  // Cleanup from syntax_err();
  while (blk) {
    llist_traverse(blk->fdelete, free);
    unredirect(blk->urd);
    free(llist_pop(&blk));
  }

  return;
}

// Parse and run a self-contained command line with no prompt/continuation
static int sh_run(char *new)
{
  struct sh_function scratch;
  int rc;

// TODO switch the fmemopen for -c to use this? Error checking? $(blah)

  memset(&scratch, 0, sizeof(struct sh_function));
  if (!parse_line(new, &scratch)) run_function(scratch.pipeline);
  free_function(&scratch);
  rc = toys.exitval;
  toys.exitval = 0;

  return rc;
}

// Print prompt to stderr, parsing escapes
// Truncated to 4k at the moment, waiting for somebody to complain.
static void do_prompt(char *prompt)
{
  char *s, *ss, c, cc, *pp = toybuf;
  int len, ll;

  if (!prompt) prompt = "\\$ ";
  while ((len = sizeof(toybuf)-(pp-toybuf))>0 && *prompt) {
    c = *(prompt++);

    if (c=='!') {
      if (*prompt=='!') prompt++;
      else {
        pp += snprintf(pp, len, "%ld", TT.lineno);
        continue;
      }
    } else if (c=='\\') {
      cc = *(prompt++);
      if (!cc) {
        *pp++ = c;
        break;
      }

      // \nnn \dD{}hHjlstT@AuvVwW!#$
      // Ignore bash's "nonprintable" hack; query our cursor position instead.
      if (cc=='[' || cc==']') continue;
      else if (cc=='$') *pp++ = getuid() ? '$' : '#';
      else if (cc=='h' || cc=='H') {
        *pp = 0;
        gethostname(pp, len);
        pp[len-1] = 0;
        if (cc=='h' && (s = strchr(pp, '.'))) *s = 0;
        pp += strlen(pp);
      } else if (cc=='s') {
        s = getbasename(*toys.argv);
        while (*s && len--) *pp++ = *s++;
      } else if (cc=='w') {
        if ((s = getvar("PWD"))) {
          if ((ss = getvar("HOME")) && strstart(&s, ss)) {
            *pp++ = '~';
            if (--len && *s!='/') *pp++ = '/';
            len--;
          }
          if (len>0) {
            ll = strlen(s);
            pp = stpncpy(pp, s, ll>len ? len : ll);
          }
        }
      } else if (!(c = unescape(cc))) {
        *pp++ = '\\';
        if (--len) *pp++ = c;
      } else *pp++ = c;
    } else *pp++ = c;
  }
  len = pp-toybuf;
  if (len>=sizeof(toybuf)) len = sizeof(toybuf);
  writeall(2, toybuf, len);
}

// only set local variable when global not present, does not extend array
static struct sh_vars *initlocal(char *name, char *val)
{
  return addvar(xmprintf("%s=%s", name, val ? val : ""));
}

// export malloced name=value string
static void export(char *str)
{
  struct sh_vars *shv;
  char *s;

  // Make sure variable exists and is updated
  if (strchr(str, '=')) shv = setvar(xstrdup(str));
  else if (!findvar(str)) shv = addvar(str = xmprintf("%s=", str));
  if (!shv || (shv->flags&VAR_GLOBAL)) return;

  // Resolve local magic for export
  if (shv->flags&VAR_MAGIC) {
    s = shv->str;
    shv->str = xmprintf("%.*s=%s", (int)(varend(str)-str), str, getvar(str));
    free(s);
  }

  xsetenv(shv->str, 0);
  shv->flags |= VAR_GLOBAL;
}

static void unexport(char *str)
{
  struct sh_vars *shv = findvar(str);

  if (shv) {
    if (shv->flags&VAR_GLOBAL) shv->str = xpop_env(str);
    shv->flags &=~VAR_GLOBAL;
  }
  if (strchr(str, '=')) setvar(str);
}

// init locals, sanitize environment, handle nommu subshell handoff
static void subshell_setup(void)
{
  struct passwd *pw = getpwuid(getuid());
  int ii, to, from, pid, ppid, zpid, myppid = getppid(), len;
// TODO: you can unset readonly and these first 4 aren't malloc()
  char *s, *ss, *magic[] = {"SECONDS","RANDOM","LINENO","GROUPS"},
    *readonly[] = {xmprintf("EUID=%d", geteuid()), xmprintf("UID=%d", getuid()),
                   xmprintf("PPID=%d", myppid)};
  struct stat st;
  struct utsname uu;
  FILE *fp;

  // Initialize magic and read only local variables
  srandom(TT.SECONDS = millitime());
  for (ii = 0; ii<ARRAY_LEN(magic); ii++)
    initlocal(magic[ii], "")->flags = VAR_MAGIC|(VAR_INT*('G'!=*magic[ii]));
  for (ii = 0; ii<ARRAY_LEN(readonly); ii++)
    addvar(readonly[ii])->flags = VAR_READONLY|VAR_INT;

  // Add local variables that can be overwritten
  initlocal("PATH", _PATH_DEFPATH);
  if (!pw) pw = (void *)toybuf; // first use, so still zeroed
  initlocal("HOME", *pw->pw_dir ? pw->pw_dir : "/");
  initlocal("SHELL", pw->pw_shell);
  initlocal("USER", pw->pw_name);
  initlocal("LOGNAME", pw->pw_name);
  gethostname(toybuf, sizeof(toybuf)-1);
  initlocal("HOSTNAME", toybuf);
  uname(&uu);
  initlocal("HOSTTYPE", uu.machine);
  sprintf(toybuf, "%s-unknown-linux", uu.machine);
  initlocal("MACHTYPE", toybuf);
  initlocal("OSTYPE", uu.sysname);
  // sprintf(toybuf, "%s-toybox", TOYBOX_VERSION);
  // initlocal("BASH_VERSION", toybuf);
  initlocal("OPTERR", "1"); // TODO: test if already exported?
  if (readlink0("/proc/self/exe", toybuf, sizeof(toybuf)))
    initlocal("BASH", toybuf);

  // Ensure environ copied and toys.envc set, and clean out illegal entries
  TT.ifs = " \t\n";
  for (to = from = pid = ppid = zpid = 0; (s = environ[from]); from++) {

    // If nommu subshell gets handoff
    if (!CFG_TOYBOX_FORK && !toys.stacktop) {
      len = 0;
      sscanf(s, "@%d,%d%n", &pid, &ppid, &len);
      if (s[len]) pid = ppid = 0;
      if (*s == '$' && s[1] == '=') zpid = atoi(s+2);
    }

    // Filter out non-shell variable names from inherited environ.
    // (haven't xsetenv() yet so no need to free() or adjust toys.envc)
    ss = varend(s);
    if (*ss == '=') {
      struct sh_vars *shv = findvar(s);

      if (!shv) addvar(environ[from])->flags = VAR_GLOBAL;
      else if (shv->flags&VAR_READONLY) continue;
      else {
        shv->flags |= VAR_GLOBAL;
        free(shv->str);
        shv->str = s;
      }
      environ[to++] = s;
    }
    if (!memcmp(s, "IFS=", 4)) TT.ifs = s+4;
  }
  environ[toys.optc = to] = 0;

  // set/update PWD
  sh_run("cd .");

  // set _ to path to this shell
  s = toys.argv[0];
  ss = 0;
  if (!strchr(s, '/')) {
    if ((ss = getcwd(0, 0))) {
      s = xmprintf("%s/%s", ss, s);
      free(ss);
      ss = s;
    } else if (*toybuf) s = toybuf;
  }
  s = xsetenv("_", s);
  if (!findvar(s)) addvar(s)->flags = VAR_GLOBAL;
  free(ss);
  if (!getvar("SHLVL")) {
    s = xsetenv("SHLVL", "1");
    if (!findvar(s)) addvar(s)->flags = VAR_GLOBAL;
  }

//TODO indexed array,associative array,integer,local,nameref,readonly,uppercase
//          if (s+1<ss && strchr("aAilnru", *s)) {

  // sanity check: magic env variable, pipe status
  if (CFG_TOYBOX_FORK || toys.stacktop || pid!=getpid() || ppid!=myppid) return;
  if (fstat(254, &st) || !S_ISFIFO(st.st_mode)) error_exit(0);
  TT.pid = zpid;
  fcntl(254, F_SETFD, FD_CLOEXEC);
  fp = fdopen(254, "r");

  // This is not efficient, could array_add the local vars.
// TODO implicit exec when possible
  while ((s = xgetline(fp, 0))) to = sh_run(s);
  fclose(fp);

  toys.exitval = to;
  xexit();
}

void sh_main(void)
{
  char *new, *cc = TT.sh.c;
  struct sh_function scratch;
  int prompt = 0, ii = FLAG(i);
  struct string_list *sl = 0;
  struct sh_arg arg;
  FILE *f;

  signal(SIGPIPE, SIG_IGN);

  TT.pid = getpid();
  TT.SECONDS = time(0);
  TT.arg = &arg;
  if (!(arg.c = toys.optc)) {
    arg.v = xmalloc(2*sizeof(char *));
    arg.v[arg.c++] = *toys.argv;
    arg.v[arg.c] = 0;
  } else memcpy(arg.v = xmalloc((arg.c+1)*sizeof(char *)), toys.optargs,
      (arg.c+1)*sizeof(char *));

  // TODO euid stuff?
  // TODO login shell?
  // TODO read profile, read rc

  // if (!FLAG(noprofile)) { }

if (BUGBUG) { int fd = open("/dev/tty", O_RDWR); dup2(fd, 255); close(fd); }
  // Is this an interactive shell?
  if (ii || (!FLAG(c)&&(FLAG(s)||!toys.optc) && isatty(0))) {
    ii = 1;
    // TODO Set up signal handlers and grab control of this tty.
  }

  // Read environment for exports from parent shell. Note, calls run_sh()
  // which blanks argument sections of TT and this, so parse everything
  // we need from shell command line before that.
  subshell_setup();
  memset(&scratch, 0, sizeof(scratch));

// TODO unify fmemopen() here with sh_run
  if (cc) f = fmemopen(cc, strlen(cc), "r");
  else if (*toys.optargs) {
// TODO: syntax_err should exit from shell scripts
    if (!(f = fopen(*toys.optargs, "r"))) {
      char *pp = getvar("PATH") ? : _PATH_DEFPATH;

      for (sl = find_in_path(pp, *toys.optargs); sl; free(llist_pop(&sl)))
        if ((f = fopen(sl->str, "r"))) break;
      if (sl) llist_traverse(sl->next, free);
      else perror_exit_raw(*toys.optargs);
    }
  } else f = stdin;

  // Loop prompting and reading lines
  for (;;) {
    TT.lineno++;
    if (ii && f == stdin) {
      char *s = getvar(prompt ? "PS2" : "PS1");

      if (!s) s = prompt ? "> " : (getpid() ? "\\$ " : "# ");
      do_prompt(s);
    }

// TODO line editing/history, should set $COLUMNS $LINES and sigwinch update
    if (!(new = xgetline(f, 0))) break;
    if (sl) {
      if (*new == 0x7f) error_exit("'%s' is ELF", sl->str);
      free(sl);
      sl = 0;
    }
// TODO if (!isspace(*new)) add_to_history(line);

    // returns 0 if line consumed, command if it needs more data
    prompt = parse_line(new, &scratch);
if (BUGBUG) dump_state(&scratch);
    if (prompt != 1) {
// TODO: ./blah.sh one two three: put one two three in scratch.arg
      if (!prompt) run_function(scratch.pipeline);
      free_function(&scratch);
      prompt = 0;
    }
    free(new);
  }

  if (prompt) error_exit("%ld:unfinished line"+4*!TT.lineno, TT.lineno);
  toys.exitval = f && ferror(f);
  clearerr(stdout);
}

/********************* shell builtin functions *************************/

#define CLEANUP_sh
#define FOR_cd
#include "generated/flags.h"
void cd_main(void)
{
  char *home = getvar("HOME"), *pwd = getvar("PWD"), *dd = 0, *from, *to,
    *dest = (*toys.optargs && **toys.optargs) ? *toys.optargs : "~";
  int bad = 0;

  // TODO: CDPATH? Really?

  if (!home) home = "/";

  // expand variables
  if (dest) dd = expand_one_arg(dest, FORCE_COPY|NO_SPLIT, 0);
  if (!dd || !*dd) {
    free(dd);
    dd = xstrdup("/");
  }

  // prepend cwd or $PWD to relative path
  if (*dd != '/') {
    to = 0;
    from = pwd ? pwd : (to = getcwd(0, 0));
    if (!from) setvarval("PWD", "(nowhere)");
    else {
      from = xmprintf("%s/%s", from, dd);
      free(dd);
      free(to);
      dd = from;
    }
  }

  if (FLAG(P)) {
    struct stat st;
    char *pp;

    // Does this directory exist?
    if ((pp = xabspath(dd, 1)) && stat(pp, &st) && !S_ISDIR(st.st_mode))
      bad++, errno = ENOTDIR;
    else {
      free(dd);
      dd = pp;
    }
  } else {

    // cancel out . and .. in the string
    for (from = to = dd; *from;) {
      if (*from=='/' && from[1]=='/') from++;
      else if (*from!='/' || from[1]!='.') *to++ = *from++;
      else if (!from[2] || from[2]=='/') from += 2;
      else if (from[2]=='.' && (!from[3] || from[3]=='/')) {
        from += 3;
        while (to>dd && *--to != '/');
      } else *to++ = *from++;
    }
    if (to == dd) to++;
    if (to-dd>1 && to[-1]=='/') to--;
    *to = 0;
  }

  if (bad || chdir(dd)) perror_msg("chdir '%s'", dd);
  else {
    if (pwd) {
      setvarval("OLDPWD", pwd);
      if (TT.cdcount == 1) {
        export("OLDPWD");
        TT.cdcount++;
      }
    }
    setvarval("PWD", dd);
    if (!TT.cdcount) {
      export("PWD");
      TT.cdcount++;
    }
  }
  free(dd);
}

void exit_main(void)
{
  exit(*toys.optargs ? atoi(*toys.optargs) : 0);
}

void unset_main(void)
{
  char **arg, *s;

  for (arg = toys.optargs; *arg; arg++) {
    s = varend(*arg);
    if (s == *arg || *s) {
      error_msg("bad '%s'", *arg);
      continue;
    }

    // unset magic variable?
    if (!strcmp(*arg, "IFS")) TT.ifs = " \t\n";
    unsetvar(*arg);
  }
}

#define CLEANUP_cd
#define FOR_export
#include "generated/flags.h"

void export_main(void)
{
  char **arg, *eq;

  // list existing variables?
  if (!toys.optc) {
    for (arg = environ; *arg; arg++) xprintf("declare -x %s\n", *arg);
    return;
  }

  // set/move variables
  for (arg = toys.optargs; *arg; arg++) {
    eq = varend(*arg);
    if (eq == *arg || (*eq && *eq != '=')) {
      error_msg("bad %s", *arg);
      continue;
    }

    if (FLAG(n)) unexport(*arg);
    else export(*arg);
  }
}

void eval_main(void)
{
  int len = 1;
  char *s;

  sh_run(s = merge_args("", toys.optc+1, toys.argv, " ", &len, ""));
  free(s);
}

#define CLEANUP_export
#define FOR_exec
#include "generated/flags.h"

void exec_main(void)
{
  char *ee[1] = {0}, *cc, *pp = getvar("PATH");
  struct string_list *sl;

  // discard redirects and return if nothing to exec
  free(TT.pp->urd);
  TT.pp->urd = 0;
  if (!toys.optc) return;

  // exec, handling -acl
  cc = *toys.optargs;
  if (TT.exec.a || FLAG(l))
    *toys.optargs = xmprintf("%s%s", FLAG(l)?"-":"", TT.exec.a?TT.exec.a:cc);
  for (sl = find_in_path(pp?pp:_PATH_DEFPATH, cc); sl; free(llist_pop(&sl)))
    execve(sl->str, toys.optargs, FLAG(c) ? ee : environ);

  // report error (usually ENOENT) and return
  perror_msg("%s", cc);
  toys.exitval = 127;
}