aboutsummaryrefslogtreecommitdiff
path: root/miscutils/less.c
blob: d1d4a71be815fbf09c3b0c8513776c16d615e015 (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
/* vi: set sw=4 ts=4: */
/*
 * Mini less implementation for busybox
 *
 * Copyright (C) 2005 by Rob Sullivan <cogito.ergo.cogito@gmail.com>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

/*
 * TODO:
 * - Add more regular expression support - search modifiers, certain matches, etc.
 * - Add more complex bracket searching - currently, nested brackets are
 *   not considered.
 * - Add support for "F" as an input. This causes less to act in
 *   a similar way to tail -f.
 * - Allow horizontal scrolling.
 *
 * Notes:
 * - the inp file pointer is used so that keyboard input works after
 *   redirected input has been read from stdin
 */

//config:config LESS
//config:	bool "less"
//config:	default y
//config:	help
//config:	  'less' is a pager, meaning that it displays text files. It possesses
//config:	  a wide array of features, and is an improvement over 'more'.
//config:
//config:config FEATURE_LESS_MAXLINES
//config:	int "Max number of input lines less will try to eat"
//config:	default 9999999
//config:	depends on LESS
//config:
//config:config FEATURE_LESS_BRACKETS
//config:	bool "Enable bracket searching"
//config:	default y
//config:	depends on LESS
//config:	help
//config:	  This option adds the capability to search for matching left and right
//config:	  brackets, facilitating programming.
//config:
//config:config FEATURE_LESS_FLAGS
//config:	bool "Enable -m/-M"
//config:	default y
//config:	depends on LESS
//config:	help
//config:	  The -M/-m flag enables a more sophisticated status line.
//config:
//config:config FEATURE_LESS_TRUNCATE
//config:	bool "Enable -S"
//config:	default y
//config:	depends on LESS
//config:	help
//config:	  The -S flag causes long lines to be truncated rather than
//config:	  wrapped.
//config:
//config:config FEATURE_LESS_MARKS
//config:	bool "Enable marks"
//config:	default y
//config:	depends on LESS
//config:	help
//config:	  Marks enable positions in a file to be stored for easy reference.
//config:
//config:config FEATURE_LESS_REGEXP
//config:	bool "Enable regular expressions"
//config:	default y
//config:	depends on LESS
//config:	help
//config:	  Enable regular expressions, allowing complex file searches.
//config:
//config:config FEATURE_LESS_WINCH
//config:	bool "Enable automatic resizing on window size changes"
//config:	default y
//config:	depends on LESS
//config:	help
//config:	  Makes less track window size changes.
//config:
//config:config FEATURE_LESS_ASK_TERMINAL
//config:	bool "Use 'tell me cursor position' ESC sequence to measure window"
//config:	default y
//config:	depends on FEATURE_LESS_WINCH
//config:	help
//config:	  Makes less track window size changes.
//config:	  If terminal size can't be retrieved and $LINES/$COLUMNS are not set,
//config:	  this option makes less perform a last-ditch effort to find it:
//config:	  position cursor to 999,999 and ask terminal to report real
//config:	  cursor position using "ESC [ 6 n" escape sequence, then read stdin.
//config:
//config:	  This is not clean but helps a lot on serial lines and such.
//config:
//config:config FEATURE_LESS_DASHCMD
//config:	bool "Enable flag changes ('-' command)"
//config:	default y
//config:	depends on LESS
//config:	help
//config:	  This enables the ability to change command-line flags within
//config:	  less itself ('-' keyboard command).
//config:
//config:config FEATURE_LESS_LINENUMS
//config:	bool "Enable dynamic switching of line numbers"
//config:	default y
//config:	depends on FEATURE_LESS_DASHCMD
//config:	help
//config:	  Enables "-N" command.

//usage:#define less_trivial_usage
//usage:       "[-E" IF_FEATURE_LESS_REGEXP("I")IF_FEATURE_LESS_FLAGS("Mm")
//usage:       "N" IF_FEATURE_LESS_TRUNCATE("S") "h~] [FILE]..."
//usage:#define less_full_usage "\n\n"
//usage:       "View FILE (or stdin) one screenful at a time\n"
//usage:     "\n	-E	Quit once the end of a file is reached"
//usage:	IF_FEATURE_LESS_REGEXP(
//usage:     "\n	-I	Ignore case in all searches"
//usage:	)
//usage:	IF_FEATURE_LESS_FLAGS(
//usage:     "\n	-M,-m	Display status line with line numbers"
//usage:     "\n		and percentage through the file"
//usage:	)
//usage:     "\n	-N	Prefix line number to each line"
//usage:	IF_FEATURE_LESS_TRUNCATE(
//usage:     "\n	-S	Truncate long lines"
//usage:	)
//usage:     "\n	-~	Suppress ~s displayed past EOF"

#include <sched.h>  /* sched_yield() */

#include "libbb.h"
#include "common_bufsiz.h"
#if ENABLE_FEATURE_LESS_REGEXP
#include "xregex.h"
#endif


#define ESC "\033"
/* The escape codes for highlighted and normal text */
#define HIGHLIGHT   ESC"[7m"
#define NORMAL      ESC"[0m"
/* The escape code to home and clear to the end of screen */
#define CLEAR       ESC"[H\033[J"
/* The escape code to clear to the end of line */
#define CLEAR_2_EOL ESC"[K"

enum {
/* Absolute max of lines eaten */
	MAXLINES = CONFIG_FEATURE_LESS_MAXLINES,
/* This many "after the end" lines we will show (at max) */
	TILDES = 1,
};

/* Command line options */
enum {
	FLAG_E = 1 << 0,
	FLAG_M = 1 << 1,
	FLAG_m = 1 << 2,
	FLAG_N = 1 << 3,
	FLAG_TILDE = 1 << 4,
	FLAG_I = 1 << 5,
	FLAG_S = (1 << 6) * ENABLE_FEATURE_LESS_TRUNCATE,
/* hijack command line options variable for internal state vars */
	LESS_STATE_MATCH_BACKWARDS = 1 << 15,
};

#if !ENABLE_FEATURE_LESS_REGEXP
enum { pattern_valid = 0 };
#endif

struct globals {
	int cur_fline; /* signed */
	int kbd_fd;  /* fd to get input from */
	int less_gets_pos;
/* last position in last line, taking into account tabs */
	size_t last_line_pos;
	unsigned max_fline;
	unsigned max_lineno; /* this one tracks linewrap */
	unsigned max_displayed_line;
	unsigned width;
#if ENABLE_FEATURE_LESS_WINCH
	unsigned winch_counter;
#endif
	ssize_t eof_error; /* eof if 0, error if < 0 */
	ssize_t readpos;
	ssize_t readeof; /* must be signed */
	const char **buffer;
	const char **flines;
	const char *empty_line_marker;
	unsigned num_files;
	unsigned current_file;
	char *filename;
	char **files;
#if ENABLE_FEATURE_LESS_FLAGS
	int num_lines; /* a flag if < 0, line count if >= 0 */
# define REOPEN_AND_COUNT (-1)
# define REOPEN_STDIN     (-2)
# define NOT_REGULAR_FILE (-3)
#endif
#if ENABLE_FEATURE_LESS_MARKS
	unsigned num_marks;
	unsigned mark_lines[15][2];
#endif
#if ENABLE_FEATURE_LESS_REGEXP
	unsigned *match_lines;
	int match_pos; /* signed! */
	int wanted_match; /* signed! */
	int num_matches;
	regex_t pattern;
	smallint pattern_valid;
#endif
#if ENABLE_FEATURE_LESS_ASK_TERMINAL
	smallint winsize_err;
#endif
	smallint terminated;
	struct termios term_orig, term_less;
	char kbd_input[KEYCODE_BUFFER_SIZE];
};
#define G (*ptr_to_globals)
#define cur_fline           (G.cur_fline         )
#define kbd_fd              (G.kbd_fd            )
#define less_gets_pos       (G.less_gets_pos     )
#define last_line_pos       (G.last_line_pos     )
#define max_fline           (G.max_fline         )
#define max_lineno          (G.max_lineno        )
#define max_displayed_line  (G.max_displayed_line)
#define width               (G.width             )
#define winch_counter       (G.winch_counter     )
/* This one is 100% not cached by compiler on read access */
#define WINCH_COUNTER (*(volatile unsigned *)&winch_counter)
#define eof_error           (G.eof_error         )
#define readpos             (G.readpos           )
#define readeof             (G.readeof           )
#define buffer              (G.buffer            )
#define flines              (G.flines            )
#define empty_line_marker   (G.empty_line_marker )
#define num_files           (G.num_files         )
#define current_file        (G.current_file      )
#define filename            (G.filename          )
#define files               (G.files             )
#define num_lines           (G.num_lines         )
#define num_marks           (G.num_marks         )
#define mark_lines          (G.mark_lines        )
#if ENABLE_FEATURE_LESS_REGEXP
#define match_lines         (G.match_lines       )
#define match_pos           (G.match_pos         )
#define num_matches         (G.num_matches       )
#define wanted_match        (G.wanted_match      )
#define pattern             (G.pattern           )
#define pattern_valid       (G.pattern_valid     )
#endif
#define terminated          (G.terminated        )
#define term_orig           (G.term_orig         )
#define term_less           (G.term_less         )
#define kbd_input           (G.kbd_input         )
#define INIT_G() do { \
	SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
	less_gets_pos = -1; \
	empty_line_marker = "~"; \
	num_files = 1; \
	current_file = 1; \
	eof_error = 1; \
	terminated = 1; \
	IF_FEATURE_LESS_REGEXP(wanted_match = -1;) \
} while (0)

/* flines[] are lines read from stdin, each in malloc'ed buffer.
 * Line numbers are stored as uint32_t prepended to each line.
 * Pointer is adjusted so that flines[i] points directly past
 * line number. Accesor: */
#define MEMPTR(p) ((char*)(p) - 4)
#define LINENO(p) (*(uint32_t*)((p) - 4))


/* Reset terminal input to normal */
static void set_tty_cooked(void)
{
	fflush_all();
	tcsetattr(kbd_fd, TCSANOW, &term_orig);
}

/* Move the cursor to a position (x,y), where (0,0) is the
   top-left corner of the console */
static void move_cursor(int line, int row)
{
	printf(ESC"[%u;%uH", line, row);
}

static void clear_line(void)
{
	printf(ESC"[%u;0H" CLEAR_2_EOL, max_displayed_line + 2);
}

static void print_hilite(const char *str)
{
	printf(HIGHLIGHT"%s"NORMAL, str);
}

static void print_statusline(const char *str)
{
	clear_line();
	printf(HIGHLIGHT"%.*s"NORMAL, width - 1, str);
}

/* Exit the program gracefully */
static void less_exit(int code)
{
	set_tty_cooked();
	clear_line();
	if (code < 0)
		kill_myself_with_sig(- code); /* does not return */
	exit(code);
}

#if (ENABLE_FEATURE_LESS_DASHCMD && ENABLE_FEATURE_LESS_LINENUMS) \
 || ENABLE_FEATURE_LESS_WINCH
static void re_wrap(void)
{
	int w = width;
	int new_line_pos;
	int src_idx;
	int dst_idx;
	int new_cur_fline = 0;
	uint32_t lineno;
	char linebuf[w + 1];
	const char **old_flines = flines;
	const char *s;
	char **new_flines = NULL;
	char *d;

	if (option_mask32 & FLAG_N)
		w -= 8;

	src_idx = 0;
	dst_idx = 0;
	s = old_flines[0];
	lineno = LINENO(s);
	d = linebuf;
	new_line_pos = 0;
	while (1) {
		*d = *s;
		if (*d != '\0') {
			new_line_pos++;
			if (*d == '\t') { /* tab */
				new_line_pos += 7;
				new_line_pos &= (~7);
			}
			s++;
			d++;
			if (new_line_pos >= w) {
				int sz;
				/* new line is full, create next one */
				*d = '\0';
 next_new:
				sz = (d - linebuf) + 1; /* + 1: NUL */
				d = ((char*)xmalloc(sz + 4)) + 4;
				LINENO(d) = lineno;
				memcpy(d, linebuf, sz);
				new_flines = xrealloc_vector(new_flines, 8, dst_idx);
				new_flines[dst_idx] = d;
				dst_idx++;
				if (new_line_pos < w) {
					/* if we came here thru "goto next_new" */
					if (src_idx > max_fline)
						break;
					lineno = LINENO(s);
				}
				d = linebuf;
				new_line_pos = 0;
			}
			continue;
		}
		/* *d == NUL: old line ended, go to next old one */
		free(MEMPTR(old_flines[src_idx]));
		/* btw, convert cur_fline... */
		if (cur_fline == src_idx)
			new_cur_fline = dst_idx;
		src_idx++;
		/* no more lines? finish last new line (and exit the loop) */
		if (src_idx > max_fline)
			goto next_new;
		s = old_flines[src_idx];
		if (lineno != LINENO(s)) {
			/* this is not a continuation line!
			 * create next _new_ line too */
			goto next_new;
		}
	}

	free(old_flines);
	flines = (const char **)new_flines;

	max_fline = dst_idx - 1;
	last_line_pos = new_line_pos;
	cur_fline = new_cur_fline;
	/* max_lineno is screen-size independent */
#if ENABLE_FEATURE_LESS_REGEXP
	pattern_valid = 0;
#endif
}
#endif

#if ENABLE_FEATURE_LESS_REGEXP
static void fill_match_lines(unsigned pos);
#else
#define fill_match_lines(pos) ((void)0)
#endif

static int at_end(void)
{
	return (option_mask32 & FLAG_S)
		? !(cur_fline <= max_fline &&
			max_lineno > LINENO(flines[cur_fline]) + max_displayed_line)
		: !(max_fline > cur_fline + max_displayed_line);
}

/* Devilishly complex routine.
 *
 * Has to deal with EOF and EPIPE on input,
 * with line wrapping, with last line not ending in '\n'
 * (possibly not ending YET!), with backspace and tabs.
 * It reads input again if last time we got an EOF (thus supporting
 * growing files) or EPIPE (watching output of slow process like make).
 *
 * Variables used:
 * flines[] - array of lines already read. Linewrap may cause
 *      one source file line to occupy several flines[n].
 * flines[max_fline] - last line, possibly incomplete.
 * terminated - 1 if flines[max_fline] is 'terminated'
 *      (if there was '\n' [which isn't stored itself, we just remember
 *      that it was seen])
 * max_lineno - last line's number, this one doesn't increment
 *      on line wrap, only on "real" new lines.
 * readbuf[0..readeof-1] - small preliminary buffer.
 * readbuf[readpos] - next character to add to current line.
 * last_line_pos - screen line position of next char to be read
 *      (takes into account tabs and backspaces)
 * eof_error - < 0 error, == 0 EOF, > 0 not EOF/error
 *
 * "git log -p | less -m" on the kernel git tree is a good test for EAGAINs,
 * "/search on very long input" and "reaching max line count" corner cases.
 */
static void read_lines(void)
{
	char *current_line, *p;
	int w = width;
	char last_terminated = terminated;
	time_t last_time = 0;
	int retry_EAGAIN = 2;
#if ENABLE_FEATURE_LESS_REGEXP
	unsigned old_max_fline = max_fline;
#endif

#define readbuf bb_common_bufsiz1
	setup_common_bufsiz();

	/* (careful: max_fline can be -1) */
	if (max_fline + 1 > MAXLINES)
		return;

	if (option_mask32 & FLAG_N)
		w -= 8;

	p = current_line = ((char*)xmalloc(w + 5)) + 4;
	if (!last_terminated) {
		const char *cp = flines[max_fline];
		p = stpcpy(p, cp);
		free(MEMPTR(cp));
		/* last_line_pos is still valid from previous read_lines() */
	} else {
		max_fline++;
		last_line_pos = 0;
	}

	while (1) { /* read lines until we reach cur_fline or wanted_match */
		*p = '\0';
		terminated = 0;
		while (1) { /* read chars until we have a line */
			char c;
			/* if no unprocessed chars left, eat more */
			if (readpos >= readeof) {
				int flags = ndelay_on(0);

				while (1) {
					time_t t;

					errno = 0;
					eof_error = safe_read(STDIN_FILENO, readbuf, COMMON_BUFSIZE);
					if (errno != EAGAIN)
						break;
					t = time(NULL);
					if (t != last_time) {
						last_time = t;
						if (--retry_EAGAIN < 0)
							break;
					}
					sched_yield();
				}
				fcntl(0, F_SETFL, flags); /* ndelay_off(0) */
				readpos = 0;
				readeof = eof_error;
				if (eof_error <= 0)
					goto reached_eof;
				retry_EAGAIN = 1;
			}
			c = readbuf[readpos];
			/* backspace? [needed for manpages] */
			/* <tab><bs> is (a) insane and */
			/* (b) harder to do correctly, so we refuse to do it */
			if (c == '\x8' && last_line_pos && p[-1] != '\t') {
				readpos++; /* eat it */
				last_line_pos--;
			/* was buggy (p could end up <= current_line)... */
				*--p = '\0';
				continue;
			}
			{
				size_t new_last_line_pos = last_line_pos + 1;
				if (c == '\t') {
					new_last_line_pos += 7;
					new_last_line_pos &= (~7);
				}
				if ((int)new_last_line_pos > w)
					break;
				last_line_pos = new_last_line_pos;
			}
			/* ok, we will eat this char */
			readpos++;
			if (c == '\n') {
				terminated = 1;
				last_line_pos = 0;
				break;
			}
			/* NUL is substituted by '\n'! */
			if (c == '\0') c = '\n';
			*p++ = c;
			*p = '\0';
		} /* end of "read chars until we have a line" loop */
#if 0
//BUG: also triggers on this:
// { printf "\nfoo\n"; sleep 1; printf "\nbar\n"; } | less
// (resulting in lost empty line between "foo" and "bar" lines)
// the "terminated" logic needs fixing (or explaining)
		/* Corner case: linewrap with only "" wrapping to next line */
		/* Looks ugly on screen, so we do not store this empty line */
		if (!last_terminated && !current_line[0]) {
			last_terminated = 1;
			max_lineno++;
			continue;
		}
#endif
 reached_eof:
		last_terminated = terminated;
		flines = xrealloc_vector(flines, 8, max_fline);

		flines[max_fline] = (char*)xrealloc(MEMPTR(current_line), strlen(current_line) + 1 + 4) + 4;
		LINENO(flines[max_fline]) = max_lineno;
		if (terminated)
			max_lineno++;

		if (max_fline >= MAXLINES) {
			eof_error = 0; /* Pretend we saw EOF */
			break;
		}
		if (!at_end()) {
#if !ENABLE_FEATURE_LESS_REGEXP
			break;
#else
			if (wanted_match >= num_matches) { /* goto_match called us */
				fill_match_lines(old_max_fline);
				old_max_fline = max_fline;
			}
			if (wanted_match < num_matches)
				break;
#endif
		}
		if (eof_error <= 0) {
			break;
		}
		max_fline++;
		current_line = ((char*)xmalloc(w + 5)) + 4;
		p = current_line;
		last_line_pos = 0;
	} /* end of "read lines until we reach cur_fline" loop */

	if (eof_error < 0) {
		if (errno == EAGAIN) {
			eof_error = 1;
		} else {
			print_statusline(bb_msg_read_error);
		}
	}
#if ENABLE_FEATURE_LESS_FLAGS
	else if (eof_error == 0)
		num_lines = max_lineno;
#endif

	fill_match_lines(old_max_fline);
#if ENABLE_FEATURE_LESS_REGEXP
	/* prevent us from being stuck in search for a match */
	wanted_match = -1;
#endif
#undef readbuf
}

#if ENABLE_FEATURE_LESS_FLAGS
static int safe_lineno(int fline)
{
	if (fline >= max_fline)
		fline = max_fline - 1;

	/* also catches empty file (max_fline == 0) */
	if (fline < 0)
		return 0;

	return LINENO(flines[fline]) + 1;
}

/* count number of lines in file */
static void update_num_lines(void)
{
	int count, fd;
	struct stat stbuf;
	ssize_t len, i;
	char buf[4096];

	/* only do this for regular files */
	if (num_lines == REOPEN_AND_COUNT || num_lines == REOPEN_STDIN) {
		count = 0;
		fd = open("/proc/self/fd/0", O_RDONLY);
		if (fd < 0 && num_lines == REOPEN_AND_COUNT) {
			/* "filename" is valid only if REOPEN_AND_COUNT */
			fd = open(filename, O_RDONLY);
		}
		if (fd < 0) {
			/* somebody stole my file! */
			num_lines = NOT_REGULAR_FILE;
			return;
		}
		if (fstat(fd, &stbuf) != 0 || !S_ISREG(stbuf.st_mode)) {
			num_lines = NOT_REGULAR_FILE;
			goto do_close;
		}
		while ((len = safe_read(fd, buf, sizeof(buf))) > 0) {
			for (i = 0; i < len; ++i) {
				if (buf[i] == '\n' && ++count == MAXLINES)
					goto done;
			}
		}
 done:
		num_lines = count;
 do_close:
		close(fd);
	}
}

/* Print a status line if -M was specified */
static void m_status_print(void)
{
	int first, last;
	unsigned percent;

	if (less_gets_pos >= 0) /* don't touch statusline while input is done! */
		return;

	clear_line();
	printf(HIGHLIGHT"%s", filename);
	if (num_files > 1)
		printf(" (file %i of %i)", current_file, num_files);

	first = safe_lineno(cur_fline);
	last = (option_mask32 & FLAG_S)
			? MIN(first + max_displayed_line, max_lineno)
			: safe_lineno(cur_fline + max_displayed_line);
	printf(" lines %i-%i", first, last);

	update_num_lines();
	if (num_lines >= 0)
		printf("/%i", num_lines);

	if (at_end()) {
		printf(" (END)");
		if (num_files > 1 && current_file != num_files)
			printf(" - next: %s", files[current_file]);
	} else if (num_lines > 0) {
		percent = (100 * last + num_lines/2) / num_lines;
		printf(" %i%%", percent <= 100 ? percent : 100);
	}
	printf(NORMAL);
}
#endif

/* Print the status line */
static void status_print(void)
{
	const char *p;

	if (less_gets_pos >= 0) /* don't touch statusline while input is done! */
		return;

	/* Change the status if flags have been set */
#if ENABLE_FEATURE_LESS_FLAGS
	if (option_mask32 & (FLAG_M|FLAG_m)) {
		m_status_print();
		return;
	}
	/* No flags set */
#endif

	clear_line();
	if (cur_fline && !at_end()) {
		bb_putchar(':');
		return;
	}
	p = "(END)";
	if (!cur_fline)
		p = filename;
	if (num_files > 1) {
		printf(HIGHLIGHT"%s (file %i of %i)"NORMAL,
				p, current_file, num_files);
		return;
	}
	print_hilite(p);
}

static const char controls[] ALIGN1 =
	/* NUL: never encountered; TAB: not converted */
	/**/"\x01\x02\x03\x04\x05\x06\x07\x08"  "\x0a\x0b\x0c\x0d\x0e\x0f"
	"\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f"
	"\x7f\x9b"; /* DEL and infamous Meta-ESC :( */
static const char ctrlconv[] ALIGN1 =
	/* why 40 instead of 4a below? - it is a replacement for '\n'.
	 * '\n' is a former NUL - we subst it with @, not J */
	"\x40\x41\x42\x43\x44\x45\x46\x47\x48\x49\x40\x4b\x4c\x4d\x4e\x4f"
	"\x50\x51\x52\x53\x54\x55\x56\x57\x58\x59\x5a\x5b\x5c\x5d\x5e\x5f";

static void print_lineno(const char *line)
{
	const char *fmt = "        ";
	unsigned n = n; /* for compiler */

	if (line != empty_line_marker) {
		/* Width of 7 preserves tab spacing in the text */
		fmt = "%7u ";
		n = LINENO(line) + 1;
		if (n > 9999999 && MAXLINES > 9999999) {
			n %= 10000000;
			fmt = "%07u ";
		}
	}
	printf(fmt, n);
}


#if ENABLE_FEATURE_LESS_REGEXP
static void print_found(const char *line)
{
	int match_status;
	int eflags;
	char *growline;
	regmatch_t match_structs;

	char buf[width+1];
	const char *str = line;
	char *p = buf;
	size_t n;

	while (*str) {
		n = strcspn(str, controls);
		if (n) {
			if (!str[n]) break;
			memcpy(p, str, n);
			p += n;
			str += n;
		}
		n = strspn(str, controls);
		memset(p, '.', n);
		p += n;
		str += n;
	}
	strcpy(p, str);

	/* buf[] holds quarantined version of str */

	/* Each part of the line that matches has the HIGHLIGHT
	 * and NORMAL escape sequences placed around it.
	 * NB: we regex against line, but insert text
	 * from quarantined copy (buf[]) */
	str = buf;
	growline = NULL;
	eflags = 0;
	goto start;

	while (match_status == 0) {
		char *new = xasprintf("%s%.*s"HIGHLIGHT"%.*s"NORMAL,
				growline ? growline : "",
				(int)match_structs.rm_so, str,
				(int)(match_structs.rm_eo - match_structs.rm_so),
						str + match_structs.rm_so);
		free(growline);
		growline = new;
		str += match_structs.rm_eo;
		line += match_structs.rm_eo;
		eflags = REG_NOTBOL;
 start:
		/* Most of the time doesn't find the regex, optimize for that */
		match_status = regexec(&pattern, line, 1, &match_structs, eflags);
		/* if even "" matches, treat it as "not a match" */
		if (match_structs.rm_so >= match_structs.rm_eo)
			match_status = 1;
	}

	printf("%s%s\n", growline ? growline : "", str);
	free(growline);
}
#else
void print_found(const char *line);
#endif

static void print_ascii(const char *str)
{
	char buf[width+1];
	char *p;
	size_t n;

	while (*str) {
		n = strcspn(str, controls);
		if (n) {
			if (!str[n]) break;
			printf("%.*s", (int) n, str);
			str += n;
		}
		n = strspn(str, controls);
		p = buf;
		do {
			if (*str == 0x7f)
				*p++ = '?';
			else if (*str == (char)0x9b)
			/* VT100's CSI, aka Meta-ESC. Who's inventor? */
			/* I want to know who committed this sin */
				*p++ = '{';
			else
				*p++ = ctrlconv[(unsigned char)*str];
			str++;
		} while (--n);
		*p = '\0';
		print_hilite(buf);
	}
	puts(str);
}

/* Print the buffer */
static void buffer_print(void)
{
	unsigned i;

	move_cursor(0, 0);
	for (i = 0; i <= max_displayed_line; i++) {
		printf(CLEAR_2_EOL);
		if (option_mask32 & FLAG_N)
			print_lineno(buffer[i]);
		if (pattern_valid)
			print_found(buffer[i]);
		else
			print_ascii(buffer[i]);
	}
	if ((option_mask32 & FLAG_E)
	 && eof_error <= 0
	 && (max_fline - cur_fline) <= max_displayed_line
	) {
		less_exit(EXIT_SUCCESS);
	}
	status_print();
}

static void buffer_fill_and_print(void)
{
	unsigned i;
#if ENABLE_FEATURE_LESS_TRUNCATE
	int fpos = cur_fline;

	if (option_mask32 & FLAG_S) {
		/* Go back to the beginning of this line */
		while (fpos && LINENO(flines[fpos]) == LINENO(flines[fpos-1]))
			fpos--;
	}

	i = 0;
	while (i <= max_displayed_line && fpos <= max_fline) {
		int lineno = LINENO(flines[fpos]);
		buffer[i] = flines[fpos];
		i++;
		do {
			fpos++;
		} while ((fpos <= max_fline)
		      && (option_mask32 & FLAG_S)
		      && lineno == LINENO(flines[fpos])
		);
	}
#else
	for (i = 0; i <= max_displayed_line && cur_fline + i <= max_fline; i++) {
		buffer[i] = flines[cur_fline + i];
	}
#endif
	for (; i <= max_displayed_line; i++) {
		buffer[i] = empty_line_marker;
	}
	buffer_print();
}

/* move cur_fline to a given line number, reading lines if necessary */
static void goto_lineno(int target)
{
	if (target <= 0 ) {
		cur_fline = 0;
	}
	else if (target > LINENO(flines[cur_fline])) {
 retry:
		while (LINENO(flines[cur_fline]) != target && cur_fline < max_fline)
			++cur_fline;
		/* target not reached but more input is available */
		if (LINENO(flines[cur_fline]) != target && eof_error > 0) {
			read_lines();
			goto retry;
		}
	}
	else {
		/* search backwards through already-read lines */
		while (LINENO(flines[cur_fline]) != target && cur_fline > 0)
			--cur_fline;
	}
}

static void cap_cur_fline(void)
{
	if ((option_mask32 & FLAG_S)) {
		if (cur_fline > max_fline)
			cur_fline = max_fline;
		if (LINENO(flines[cur_fline]) + max_displayed_line > max_lineno + TILDES) {
			goto_lineno(max_lineno - max_displayed_line + TILDES);
			read_lines();
		}
	}
	else {
		if (cur_fline + max_displayed_line > max_fline + TILDES)
			cur_fline = max_fline - max_displayed_line + TILDES;
		if (cur_fline < 0)
			cur_fline = 0;
	}
}

/* Move the buffer up and down in the file in order to scroll */
static void buffer_down(int nlines)
{
	if ((option_mask32 & FLAG_S))
		goto_lineno(LINENO(flines[cur_fline]) + nlines);
	else
		cur_fline += nlines;
	read_lines();
	cap_cur_fline();
	buffer_fill_and_print();
}

static void buffer_up(int nlines)
{
	if ((option_mask32 & FLAG_S)) {
		goto_lineno(LINENO(flines[cur_fline]) - nlines);
	}
	else {
		cur_fline -= nlines;
		if (cur_fline < 0)
			cur_fline = 0;
	}
	read_lines();
	buffer_fill_and_print();
}

/* display a given line where the argument can be either an index into
 * the flines array or a line number */
static void buffer_to_line(int linenum, int is_lineno)
{
	if (linenum <= 0)
		cur_fline = 0;
	else if (is_lineno)
		goto_lineno(linenum);
	else
		cur_fline = linenum;
	read_lines();
	cap_cur_fline();
	buffer_fill_and_print();
}

static void buffer_line(int linenum)
{
	buffer_to_line(linenum, FALSE);
}

static void buffer_lineno(int lineno)
{
	buffer_to_line(lineno, TRUE);
}

static void open_file_and_read_lines(void)
{
	if (filename) {
		xmove_fd(xopen(filename, O_RDONLY), STDIN_FILENO);
#if ENABLE_FEATURE_LESS_FLAGS
		num_lines = REOPEN_AND_COUNT;
#endif
	} else {
		/* "less" with no arguments in argv[] */
		/* For status line only */
		filename = xstrdup(bb_msg_standard_input);
#if ENABLE_FEATURE_LESS_FLAGS
		num_lines = REOPEN_STDIN;
#endif
	}
	readpos = 0;
	readeof = 0;
	last_line_pos = 0;
	terminated = 1;
	read_lines();
}

/* Reinitialize everything for a new file - free the memory and start over */
static void reinitialize(void)
{
	unsigned i;

	if (flines) {
		for (i = 0; i <= max_fline; i++)
			free(MEMPTR(flines[i]));
		free(flines);
		flines = NULL;
	}

	max_fline = -1;
	cur_fline = 0;
	max_lineno = 0;
	open_file_and_read_lines();
#if ENABLE_FEATURE_LESS_ASK_TERMINAL
	if (G.winsize_err)
		printf("\033[999;999H" "\033[6n");
#endif
	buffer_fill_and_print();
}

static int64_t getch_nowait(void)
{
	int rd;
	int64_t key64;
	struct pollfd pfd[2];

	pfd[0].fd = STDIN_FILENO;
	pfd[0].events = POLLIN;
	pfd[1].fd = kbd_fd;
	pfd[1].events = POLLIN;
 again:
	tcsetattr(kbd_fd, TCSANOW, &term_less);
	/* NB: select/poll returns whenever read will not block. Therefore:
	 * if eof is reached, select/poll will return immediately
	 * because read will immediately return 0 bytes.
	 * Even if select/poll says that input is available, read CAN block
	 * (switch fd into O_NONBLOCK'ed mode to avoid it)
	 */
	rd = 1;
	/* Are we interested in stdin? */
	if (at_end()) {
		if (eof_error > 0) /* did NOT reach eof yet */
			rd = 0; /* yes, we are interested in stdin */
	}
	/* Position cursor if line input is done */
	if (less_gets_pos >= 0)
		move_cursor(max_displayed_line + 2, less_gets_pos + 1);
	fflush_all();

	if (kbd_input[0] == 0) { /* if nothing is buffered */
#if ENABLE_FEATURE_LESS_WINCH
		while (1) {
			int r;
			/* NB: SIGWINCH interrupts poll() */
			r = poll(pfd + rd, 2 - rd, -1);
			if (/*r < 0 && errno == EINTR &&*/ winch_counter)
				return '\\'; /* anything which has no defined function */
			if (r) break;
		}
#else
		safe_poll(pfd + rd, 2 - rd, -1);
#endif
	}

	/* We have kbd_fd in O_NONBLOCK mode, read inside read_key()
	 * would not block even if there is no input available */
	key64 = read_key(kbd_fd, kbd_input, /*timeout off:*/ -2);
	if ((int)key64 == -1) {
		if (errno == EAGAIN) {
			/* No keyboard input available. Since poll() did return,
			 * we should have input on stdin */
			read_lines();
			buffer_fill_and_print();
			goto again;
		}
		/* EOF/error (ssh session got killed etc) */
		less_exit(0);
	}
	set_tty_cooked();
	return key64;
}

/* Grab a character from input without requiring the return key.
 * May return KEYCODE_xxx values.
 * Note that this function works best with raw input. */
static int64_t less_getch(int pos)
{
	int64_t key64;
	int key;

 again:
	less_gets_pos = pos;
	key = key64 = getch_nowait();
	less_gets_pos = -1;

	/* Discard Ctrl-something chars.
	 * (checking only lower 32 bits is a size optimization:
	 * upper 32 bits are used only by KEYCODE_CURSOR_POS)
	 */
	if (key >= 0 && key < ' ' && key != 0x0d && key != 8)
		goto again;

	return key64;
}

static char* less_gets(int sz)
{
	int c;
	unsigned i = 0;
	char *result = xzalloc(1);

	while (1) {
		c = '\0';
		less_gets_pos = sz + i;
		c = getch_nowait();
		if (c == 0x0d) {
			result[i] = '\0';
			less_gets_pos = -1;
			return result;
		}
		if (c == 0x7f)
			c = 8;
		if (c == 8 && i) {
			printf("\x8 \x8");
			i--;
		}
		if (c < ' ') /* filters out KEYCODE_xxx too (<0) */
			continue;
		if (i >= width - sz - 1)
			continue; /* len limit */
		bb_putchar(c);
		result[i++] = c;
		result = xrealloc(result, i+1);
	}
}

static void examine_file(void)
{
	char *new_fname;

	print_statusline("Examine: ");
	new_fname = less_gets(sizeof("Examine: ") - 1);
	if (!new_fname[0]) {
		status_print();
 err:
		free(new_fname);
		return;
	}
	if (access(new_fname, R_OK) != 0) {
		print_statusline("Cannot read this file");
		goto err;
	}
	free(filename);
	filename = new_fname;
	/* files start by = argv. why we assume that argv is infinitely long??
	files[num_files] = filename;
	current_file = num_files + 1;
	num_files++; */
	files[0] = filename;
	num_files = current_file = 1;
	reinitialize();
}

/* This function changes the file currently being paged. direction can be one of the following:
 * -1: go back one file
 *  0: go to the first file
 *  1: go forward one file */
static void change_file(int direction)
{
	if (current_file != ((direction > 0) ? num_files : 1)) {
		current_file = direction ? current_file + direction : 1;
		free(filename);
		filename = xstrdup(files[current_file - 1]);
		reinitialize();
	} else {
		print_statusline(direction > 0 ? "No next file" : "No previous file");
	}
}

static void remove_current_file(void)
{
	unsigned i;

	if (num_files < 2)
		return;

	if (current_file != 1) {
		change_file(-1);
		for (i = 3; i <= num_files; i++)
			files[i - 2] = files[i - 1];
		num_files--;
	} else {
		change_file(1);
		for (i = 2; i <= num_files; i++)
			files[i - 2] = files[i - 1];
		num_files--;
		current_file--;
	}
}

static void colon_process(void)
{
	int keypress;

	/* Clear the current line and print a prompt */
	print_statusline(" :");

	keypress = less_getch(2);
	switch (keypress) {
	case 'd':
		remove_current_file();
		break;
	case 'e':
		examine_file();
		break;
#if ENABLE_FEATURE_LESS_FLAGS
	case 'f':
		m_status_print();
		break;
#endif
	case 'n':
		change_file(1);
		break;
	case 'p':
		change_file(-1);
		break;
	case 'q':
		less_exit(EXIT_SUCCESS);
		break;
	case 'x':
		change_file(0);
		break;
	}
}

#if ENABLE_FEATURE_LESS_REGEXP
static void normalize_match_pos(int match)
{
	if (match >= num_matches)
		match = num_matches - 1;
	if (match < 0)
		match = 0;
	match_pos = match;
}

static void goto_match(int match)
{
	if (!pattern_valid)
		return;
	if (match < 0)
		match = 0;
	/* Try to find next match if eof isn't reached yet */
	if (match >= num_matches && eof_error > 0) {
		wanted_match = match; /* "I want to read until I see N'th match" */
		read_lines();
	}
	if (num_matches) {
		normalize_match_pos(match);
		buffer_line(match_lines[match_pos]);
	} else {
		print_statusline("No matches found");
	}
}

static void fill_match_lines(unsigned pos)
{
	if (!pattern_valid)
		return;
	/* Run the regex on each line of the current file */
	while (pos <= max_fline) {
		/* If this line matches */
		if (regexec(&pattern, flines[pos], 0, NULL, 0) == 0
		/* and we didn't match it last time */
		 && !(num_matches && match_lines[num_matches-1] == pos)
		) {
			match_lines = xrealloc_vector(match_lines, 4, num_matches);
			match_lines[num_matches++] = pos;
		}
		pos++;
	}
}

static void regex_process(void)
{
	char *uncomp_regex, *err;

	/* Reset variables */
	free(match_lines);
	match_lines = NULL;
	match_pos = 0;
	num_matches = 0;
	if (pattern_valid) {
		regfree(&pattern);
		pattern_valid = 0;
	}

	/* Get the uncompiled regular expression from the user */
	clear_line();
	bb_putchar((option_mask32 & LESS_STATE_MATCH_BACKWARDS) ? '?' : '/');
	uncomp_regex = less_gets(1);
	if (!uncomp_regex[0]) {
		free(uncomp_regex);
		buffer_print();
		return;
	}

	/* Compile the regex and check for errors */
	err = regcomp_or_errmsg(&pattern, uncomp_regex,
				(option_mask32 & FLAG_I) ? REG_ICASE : 0);
	free(uncomp_regex);
	if (err) {
		print_statusline(err);
		free(err);
		return;
	}

	pattern_valid = 1;
	match_pos = 0;
	fill_match_lines(0);
	while (match_pos < num_matches) {
		if ((int)match_lines[match_pos] > cur_fline)
			break;
		match_pos++;
	}
	if (option_mask32 & LESS_STATE_MATCH_BACKWARDS)
		match_pos--;

	/* It's possible that no matches are found yet.
	 * goto_match() will read input looking for match,
	 * if needed */
	goto_match(match_pos);
}
#endif

static void number_process(int first_digit)
{
	unsigned i;
	int num;
	int keypress;
	char num_input[sizeof(int)*4]; /* more than enough */

	num_input[0] = first_digit;

	/* Clear the current line, print a prompt, and then print the digit */
	clear_line();
	printf(":%c", first_digit);

	/* Receive input until a letter is given */
	i = 1;
	while (i < sizeof(num_input)-1) {
		keypress = less_getch(i + 1);
		if ((unsigned)keypress > 255 || !isdigit(keypress))
			break;
		num_input[i] = keypress;
		bb_putchar(keypress);
		i++;
	}

	num_input[i] = '\0';
	num = bb_strtou(num_input, NULL, 10);
	/* on format error, num == -1 */
	if (num < 1 || num > MAXLINES) {
		buffer_print();
		return;
	}

	/* We now know the number and the letter entered, so we process them */
	switch (keypress) {
	case KEYCODE_DOWN: case 'z': case 'd': case 'e': case ' ': case '\015':
		buffer_down(num);
		break;
	case KEYCODE_UP: case 'b': case 'w': case 'y': case 'u':
		buffer_up(num);
		break;
	case 'g': case '<': case 'G': case '>':
		buffer_lineno(num - 1);
		break;
	case 'p': case '%':
#if ENABLE_FEATURE_LESS_FLAGS
		update_num_lines();
		num = num * (num_lines > 0 ? num_lines : max_lineno) / 100;
#else
		num = num * max_lineno / 100;
#endif
		buffer_lineno(num);
		break;
#if ENABLE_FEATURE_LESS_REGEXP
	case 'n':
		goto_match(match_pos + num);
		break;
	case '/':
		option_mask32 &= ~LESS_STATE_MATCH_BACKWARDS;
		regex_process();
		break;
	case '?':
		option_mask32 |= LESS_STATE_MATCH_BACKWARDS;
		regex_process();
		break;
#endif
	}
}

#if ENABLE_FEATURE_LESS_DASHCMD
static void flag_change(void)
{
	int keypress;

	clear_line();
	bb_putchar('-');
	keypress = less_getch(1);

	switch (keypress) {
	case 'M':
		option_mask32 ^= FLAG_M;
		break;
	case 'm':
		option_mask32 ^= FLAG_m;
		break;
	case 'E':
		option_mask32 ^= FLAG_E;
		break;
	case '~':
		option_mask32 ^= FLAG_TILDE;
		break;
#if ENABLE_FEATURE_LESS_TRUNCATE
	case 'S':
		option_mask32 ^= FLAG_S;
		buffer_fill_and_print();
		break;
#endif
#if ENABLE_FEATURE_LESS_LINENUMS
	case 'N':
		option_mask32 ^= FLAG_N;
		re_wrap();
		buffer_fill_and_print();
		break;
#endif
	}
}

#ifdef BLOAT
static void show_flag_status(void)
{
	int keypress;
	int flag_val;

	clear_line();
	bb_putchar('_');
	keypress = less_getch(1);

	switch (keypress) {
	case 'M':
		flag_val = option_mask32 & FLAG_M;
		break;
	case 'm':
		flag_val = option_mask32 & FLAG_m;
		break;
	case '~':
		flag_val = option_mask32 & FLAG_TILDE;
		break;
	case 'N':
		flag_val = option_mask32 & FLAG_N;
		break;
	case 'E':
		flag_val = option_mask32 & FLAG_E;
		break;
	default:
		flag_val = 0;
		break;
	}

	clear_line();
	printf(HIGHLIGHT"The status of the flag is: %u"NORMAL, flag_val != 0);
}
#endif

#endif /* ENABLE_FEATURE_LESS_DASHCMD */

static void save_input_to_file(void)
{
	const char *msg = "";
	char *current_line;
	unsigned i;
	FILE *fp;

	print_statusline("Log file: ");
	current_line = less_gets(sizeof("Log file: ")-1);
	if (current_line[0]) {
		fp = fopen_for_write(current_line);
		if (!fp) {
			msg = "Error opening log file";
			goto ret;
		}
		for (i = 0; i <= max_fline; i++)
			fprintf(fp, "%s\n", flines[i]);
		fclose(fp);
		msg = "Done";
	}
 ret:
	print_statusline(msg);
	free(current_line);
}

#if ENABLE_FEATURE_LESS_MARKS
static void add_mark(void)
{
	int letter;

	print_statusline("Mark: ");
	letter = less_getch(sizeof("Mark: ") - 1);

	if (isalpha(letter)) {
		/* If we exceed 15 marks, start overwriting previous ones */
		if (num_marks == 14)
			num_marks = 0;

		mark_lines[num_marks][0] = letter;
		mark_lines[num_marks][1] = cur_fline;
		num_marks++;
	} else {
		print_statusline("Invalid mark letter");
	}
}

static void goto_mark(void)
{
	int letter;
	int i;

	print_statusline("Go to mark: ");
	letter = less_getch(sizeof("Go to mark: ") - 1);
	clear_line();

	if (isalpha(letter)) {
		for (i = 0; i <= num_marks; i++)
			if (letter == mark_lines[i][0]) {
				buffer_line(mark_lines[i][1]);
				break;
			}
		if (num_marks == 14 && letter != mark_lines[14][0])
			print_statusline("Mark not set");
	} else
		print_statusline("Invalid mark letter");
}
#endif

#if ENABLE_FEATURE_LESS_BRACKETS
static char opp_bracket(char bracket)
{
	switch (bracket) {
		case '{': case '[': /* '}' == '{' + 2. Same for '[' */
			bracket++;
		case '(':           /* ')' == '(' + 1 */
			bracket++;
			break;
		case '}': case ']':
			bracket--;
		case ')':
			bracket--;
			break;
	};
	return bracket;
}

static void match_right_bracket(char bracket)
{
	unsigned i = cur_fline;

	if (i >= max_fline
	 || strchr(flines[i], bracket) == NULL
	) {
		print_statusline("No bracket in top line");
		return;
	}

	bracket = opp_bracket(bracket);
	for (; i < max_fline; i++) {
		if (strchr(flines[i], bracket) != NULL) {
			/*
			 * Line with matched right bracket becomes
			 * last visible line
			 */
			buffer_line(i - max_displayed_line);
			return;
		}
	}
	print_statusline("No matching bracket found");
}

static void match_left_bracket(char bracket)
{
	int i = cur_fline + max_displayed_line;

	if (i >= max_fline
	 || strchr(flines[i], bracket) == NULL
	) {
		print_statusline("No bracket in bottom line");
		return;
	}

	bracket = opp_bracket(bracket);
	for (; i >= 0; i--) {
		if (strchr(flines[i], bracket) != NULL) {
			/*
			 * Line with matched left bracket becomes
			 * first visible line
			 */
			buffer_line(i);
			return;
		}
	}
	print_statusline("No matching bracket found");
}
#endif  /* FEATURE_LESS_BRACKETS */

static void keypress_process(int keypress)
{
	switch (keypress) {
	case KEYCODE_DOWN: case 'e': case 'j': case 0x0d:
		buffer_down(1);
		break;
	case KEYCODE_UP: case 'y': case 'k':
		buffer_up(1);
		break;
	case KEYCODE_PAGEDOWN: case ' ': case 'z': case 'f':
		buffer_down(max_displayed_line + 1);
		break;
	case KEYCODE_PAGEUP: case 'w': case 'b':
		buffer_up(max_displayed_line + 1);
		break;
	case 'd':
		buffer_down((max_displayed_line + 1) / 2);
		break;
	case 'u':
		buffer_up((max_displayed_line + 1) / 2);
		break;
	case KEYCODE_HOME: case 'g': case 'p': case '<': case '%':
		buffer_line(0);
		break;
	case KEYCODE_END: case 'G': case '>':
		cur_fline = MAXLINES;
		read_lines();
		buffer_line(cur_fline);
		break;
	case 'q': case 'Q':
		less_exit(EXIT_SUCCESS);
		break;
#if ENABLE_FEATURE_LESS_MARKS
	case 'm':
		add_mark();
		buffer_print();
		break;
	case '\'':
		goto_mark();
		buffer_print();
		break;
#endif
	case 'r': case 'R':
		/* TODO: (1) also bind ^R, ^L to this?
		 * (2) re-measure window size?
		 */
		buffer_print();
		break;
	/*case 'R':
		full_repaint();
		break;*/
	case 's':
		save_input_to_file();
		break;
	case 'E':
		examine_file();
		break;
#if ENABLE_FEATURE_LESS_FLAGS
	case '=':
		m_status_print();
		break;
#endif
#if ENABLE_FEATURE_LESS_REGEXP
	case '/':
		option_mask32 &= ~LESS_STATE_MATCH_BACKWARDS;
		regex_process();
		break;
	case 'n':
		goto_match(match_pos + 1);
		break;
	case 'N':
		goto_match(match_pos - 1);
		break;
	case '?':
		option_mask32 |= LESS_STATE_MATCH_BACKWARDS;
		regex_process();
		break;
#endif
#if ENABLE_FEATURE_LESS_DASHCMD
	case '-':
		flag_change();
		buffer_print();
		break;
#ifdef BLOAT
	case '_':
		show_flag_status();
		break;
#endif
#endif
#if ENABLE_FEATURE_LESS_BRACKETS
	case '{': case '(': case '[':
		match_right_bracket(keypress);
		break;
	case '}': case ')': case ']':
		match_left_bracket(keypress);
		break;
#endif
	case ':':
		colon_process();
		break;
	}

	if (isdigit(keypress))
		number_process(keypress);
}

static void sig_catcher(int sig)
{
	less_exit(- sig);
}

#if ENABLE_FEATURE_LESS_WINCH
static void sigwinch_handler(int sig UNUSED_PARAM)
{
	winch_counter++;
}
#endif

int less_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int less_main(int argc, char **argv)
{
	char *tty_name;
	int tty_fd;

	INIT_G();

	/* TODO: -x: do not interpret backspace, -xx: tab also
	 * -xxx: newline also
	 * -w N: assume width N (-xxx -w 32: hex viewer of sorts)
	 * -s: condense many empty lines to one
	 *     (used by some setups for manpage display)
	 */
	getopt32(argv, "EMmN~I" IF_FEATURE_LESS_TRUNCATE("S") /*ignored:*/"s");
	argc -= optind;
	argv += optind;
	num_files = argc;
	files = argv;

	/* Another popular pager, most, detects when stdout
	 * is not a tty and turns into cat. This makes sense. */
	if (!isatty(STDOUT_FILENO))
		return bb_cat(argv);

	if (!num_files) {
		if (isatty(STDIN_FILENO)) {
			/* Just "less"? No args and no redirection? */
			bb_error_msg("missing filename");
			bb_show_usage();
		}
	} else {
		filename = xstrdup(files[0]);
	}

	if (option_mask32 & FLAG_TILDE)
		empty_line_marker = "";

	/* Some versions of less can survive w/o controlling tty,
	 * try to do the same. This also allows to specify an alternative
	 * tty via "less 1<>TTY".
	 * We don't try to use STDOUT_FILENO directly,
	 * since we want to set this fd to non-blocking mode,
	 * and not bother with restoring it on exit.
	 */
	tty_name = xmalloc_ttyname(STDOUT_FILENO);
	if (tty_name) {
		tty_fd = open(tty_name, O_RDONLY);
		free(tty_name);
		if (tty_fd < 0)
			goto try_ctty;
	} else {
		/* Try controlling tty */
 try_ctty:
		tty_fd = open(CURRENT_TTY, O_RDONLY);
		if (tty_fd < 0)
			return bb_cat(argv);
	}
	ndelay_on(tty_fd);
	kbd_fd = tty_fd; /* save in a global */

	tcgetattr(kbd_fd, &term_orig);
	term_less = term_orig;
	term_less.c_lflag &= ~(ICANON | ECHO);
	term_less.c_iflag &= ~(IXON | ICRNL);
	/*term_less.c_oflag &= ~ONLCR;*/
	term_less.c_cc[VMIN] = 1;
	term_less.c_cc[VTIME] = 0;

	IF_FEATURE_LESS_ASK_TERMINAL(G.winsize_err =) get_terminal_width_height(kbd_fd, &width, &max_displayed_line);
	/* 20: two tabstops + 4 */
	if (width < 20 || max_displayed_line < 3)
		return bb_cat(argv);
	max_displayed_line -= 2;

	/* We want to restore term_orig on exit */
	bb_signals(BB_FATAL_SIGS, sig_catcher);
#if ENABLE_FEATURE_LESS_WINCH
	signal(SIGWINCH, sigwinch_handler);
#endif

	buffer = xmalloc((max_displayed_line+1) * sizeof(char *));
	reinitialize();
	while (1) {
		int64_t keypress;

#if ENABLE_FEATURE_LESS_WINCH
		while (WINCH_COUNTER) {
 again:
			winch_counter--;
			IF_FEATURE_LESS_ASK_TERMINAL(G.winsize_err =) get_terminal_width_height(kbd_fd, &width, &max_displayed_line);
 IF_FEATURE_LESS_ASK_TERMINAL(got_size:)
			/* 20: two tabstops + 4 */
			if (width < 20)
				width = 20;
			if (max_displayed_line < 3)
				max_displayed_line = 3;
			max_displayed_line -= 2;
			free(buffer);
			buffer = xmalloc((max_displayed_line+1) * sizeof(char *));
			/* Avoid re-wrap and/or redraw if we already know
			 * we need to do it again. These ops are expensive */
			if (WINCH_COUNTER)
				goto again;
			re_wrap();
			if (WINCH_COUNTER)
				goto again;
			buffer_fill_and_print();
			/* This took some time. Loop back and check,
			 * were there another SIGWINCH? */
		}
		keypress = less_getch(-1); /* -1: do not position cursor */
# if ENABLE_FEATURE_LESS_ASK_TERMINAL
		if ((int32_t)keypress == KEYCODE_CURSOR_POS) {
			uint32_t rc = (keypress >> 32);
			width = (rc & 0x7fff);
			max_displayed_line = ((rc >> 16) & 0x7fff);
			goto got_size;
		}
# endif
#else
		keypress = less_getch(-1); /* -1: do not position cursor */
#endif
		keypress_process(keypress);
	}
}

/*
Help text of less version 418 is below.
If you are implementing something, keeping
key and/or command line switch compatibility is a good idea:


                   SUMMARY OF LESS COMMANDS

      Commands marked with * may be preceded by a number, N.
      Notes in parentheses indicate the behavior if N is given.
  h  H                 Display this help.
  q  :q  Q  :Q  ZZ     Exit.
 ---------------------------------------------------------------------------
                           MOVING
  e  ^E  j  ^N  CR  *  Forward  one line   (or N lines).
  y  ^Y  k  ^K  ^P  *  Backward one line   (or N lines).
  f  ^F  ^V  SPACE  *  Forward  one window (or N lines).
  b  ^B  ESC-v      *  Backward one window (or N lines).
  z                 *  Forward  one window (and set window to N).
  w                 *  Backward one window (and set window to N).
  ESC-SPACE         *  Forward  one window, but don't stop at end-of-file.
  d  ^D             *  Forward  one half-window (and set half-window to N).
  u  ^U             *  Backward one half-window (and set half-window to N).
  ESC-)  RightArrow *  Left  one half screen width (or N positions).
  ESC-(  LeftArrow  *  Right one half screen width (or N positions).
  F                    Forward forever; like "tail -f".
  r  ^R  ^L            Repaint screen.
  R                    Repaint screen, discarding buffered input.
        ---------------------------------------------------
        Default "window" is the screen height.
        Default "half-window" is half of the screen height.
 ---------------------------------------------------------------------------
                          SEARCHING
  /pattern          *  Search forward for (N-th) matching line.
  ?pattern          *  Search backward for (N-th) matching line.
  n                 *  Repeat previous search (for N-th occurrence).
  N                 *  Repeat previous search in reverse direction.
  ESC-n             *  Repeat previous search, spanning files.
  ESC-N             *  Repeat previous search, reverse dir. & spanning files.
  ESC-u                Undo (toggle) search highlighting.
        ---------------------------------------------------
        Search patterns may be modified by one or more of:
        ^N or !  Search for NON-matching lines.
        ^E or *  Search multiple files (pass thru END OF FILE).
        ^F or @  Start search at FIRST file (for /) or last file (for ?).
        ^K       Highlight matches, but don't move (KEEP position).
        ^R       Don't use REGULAR EXPRESSIONS.
 ---------------------------------------------------------------------------
                           JUMPING
  g  <  ESC-<       *  Go to first line in file (or line N).
  G  >  ESC->       *  Go to last line in file (or line N).
  p  %              *  Go to beginning of file (or N percent into file).
  t                 *  Go to the (N-th) next tag.
  T                 *  Go to the (N-th) previous tag.
  {  (  [           *  Find close bracket } ) ].
  }  )  ]           *  Find open bracket { ( [.
  ESC-^F <c1> <c2>  *  Find close bracket <c2>.
  ESC-^B <c1> <c2>  *  Find open bracket <c1>
        ---------------------------------------------------
        Each "find close bracket" command goes forward to the close bracket
          matching the (N-th) open bracket in the top line.
        Each "find open bracket" command goes backward to the open bracket
          matching the (N-th) close bracket in the bottom line.
  m<letter>            Mark the current position with <letter>.
  '<letter>            Go to a previously marked position.
  ''                   Go to the previous position.
  ^X^X                 Same as '.
        ---------------------------------------------------
        A mark is any upper-case or lower-case letter.
        Certain marks are predefined:
             ^  means  beginning of the file
             $  means  end of the file
 ---------------------------------------------------------------------------
                        CHANGING FILES
  :e [file]            Examine a new file.
  ^X^V                 Same as :e.
  :n                *  Examine the (N-th) next file from the command line.
  :p                *  Examine the (N-th) previous file from the command line.
  :x                *  Examine the first (or N-th) file from the command line.
  :d                   Delete the current file from the command line list.
  =  ^G  :f            Print current file name.
 ---------------------------------------------------------------------------
                    MISCELLANEOUS COMMANDS
  -<flag>              Toggle a command line option [see OPTIONS below].
  --<name>             Toggle a command line option, by name.
  _<flag>              Display the setting of a command line option.
  __<name>             Display the setting of an option, by name.
  +cmd                 Execute the less cmd each time a new file is examined.
  !command             Execute the shell command with $SHELL.
  |Xcommand            Pipe file between current pos & mark X to shell command.
  v                    Edit the current file with $VISUAL or $EDITOR.
  V                    Print version number of "less".
 ---------------------------------------------------------------------------
                           OPTIONS
        Most options may be changed either on the command line,
        or from within less by using the - or -- command.
        Options may be given in one of two forms: either a single
        character preceded by a -, or a name preceded by --.
  -?  ........  --help
                  Display help (from command line).
  -a  ........  --search-skip-screen
                  Forward search skips current screen.
  -b [N]  ....  --buffers=[N]
                  Number of buffers.
  -B  ........  --auto-buffers
                  Don't automatically allocate buffers for pipes.
  -c  ........  --clear-screen
                  Repaint by clearing rather than scrolling.
  -d  ........  --dumb
                  Dumb terminal.
  -D [xn.n]  .  --color=xn.n
                  Set screen colors. (MS-DOS only)
  -e  -E  ....  --quit-at-eof  --QUIT-AT-EOF
                  Quit at end of file.
  -f  ........  --force
                  Force open non-regular files.
  -F  ........  --quit-if-one-screen
                  Quit if entire file fits on first screen.
  -g  ........  --hilite-search
                  Highlight only last match for searches.
  -G  ........  --HILITE-SEARCH
                  Don't highlight any matches for searches.
  -h [N]  ....  --max-back-scroll=[N]
                  Backward scroll limit.
  -i  ........  --ignore-case
                  Ignore case in searches that do not contain uppercase.
  -I  ........  --IGNORE-CASE
                  Ignore case in all searches.
  -j [N]  ....  --jump-target=[N]
                  Screen position of target lines.
  -J  ........  --status-column
                  Display a status column at left edge of screen.
  -k [file]  .  --lesskey-file=[file]
                  Use a lesskey file.
  -L  ........  --no-lessopen
                  Ignore the LESSOPEN environment variable.
  -m  -M  ....  --long-prompt  --LONG-PROMPT
                  Set prompt style.
  -n  -N  ....  --line-numbers  --LINE-NUMBERS
                  Don't use line numbers.
  -o [file]  .  --log-file=[file]
                  Copy to log file (standard input only).
  -O [file]  .  --LOG-FILE=[file]
                  Copy to log file (unconditionally overwrite).
  -p [pattern]  --pattern=[pattern]
                  Start at pattern (from command line).
  -P [prompt]   --prompt=[prompt]
                  Define new prompt.
  -q  -Q  ....  --quiet  --QUIET  --silent --SILENT
                  Quiet the terminal bell.
  -r  -R  ....  --raw-control-chars  --RAW-CONTROL-CHARS
                  Output "raw" control characters.
  -s  ........  --squeeze-blank-lines
                  Squeeze multiple blank lines.
  -S  ........  --chop-long-lines
                  Chop long lines.
  -t [tag]  ..  --tag=[tag]
                  Find a tag.
  -T [tagsfile] --tag-file=[tagsfile]
                  Use an alternate tags file.
  -u  -U  ....  --underline-special  --UNDERLINE-SPECIAL
                  Change handling of backspaces.
  -V  ........  --version
                  Display the version number of "less".
  -w  ........  --hilite-unread
                  Highlight first new line after forward-screen.
  -W  ........  --HILITE-UNREAD
                  Highlight first new line after any forward movement.
  -x [N[,...]]  --tabs=[N[,...]]
                  Set tab stops.
  -X  ........  --no-init
                  Don't use termcap init/deinit strings.
                --no-keypad
                  Don't use termcap keypad init/deinit strings.
  -y [N]  ....  --max-forw-scroll=[N]
                  Forward scroll limit.
  -z [N]  ....  --window=[N]
                  Set size of window.
  -" [c[c]]  .  --quotes=[c[c]]
                  Set shell quote characters.
  -~  ........  --tilde
                  Don't display tildes after end of file.
  -# [N]  ....  --shift=[N]
                  Horizontal scroll amount (0 = one half screen width)

 ---------------------------------------------------------------------------
                          LINE EDITING
        These keys can be used to edit text being entered
        on the "command line" at the bottom of the screen.
 RightArrow                       ESC-l     Move cursor right one character.
 LeftArrow                        ESC-h     Move cursor left one character.
 CNTL-RightArrow  ESC-RightArrow  ESC-w     Move cursor right one word.
 CNTL-LeftArrow   ESC-LeftArrow   ESC-b     Move cursor left one word.
 HOME                             ESC-0     Move cursor to start of line.
 END                              ESC-$     Move cursor to end of line.
 BACKSPACE                                  Delete char to left of cursor.
 DELETE                           ESC-x     Delete char under cursor.
 CNTL-BACKSPACE   ESC-BACKSPACE             Delete word to left of cursor.
 CNTL-DELETE      ESC-DELETE      ESC-X     Delete word under cursor.
 CNTL-U           ESC (MS-DOS only)         Delete entire line.
 UpArrow                          ESC-k     Retrieve previous command line.
 DownArrow                        ESC-j     Retrieve next command line.
 TAB                                        Complete filename & cycle.
 SHIFT-TAB                        ESC-TAB   Complete filename & reverse cycle.
 CNTL-L                                     Complete filename, list all.
*/