aboutsummaryrefslogtreecommitdiff
path: root/miscutils/less.c
blob: d7898caab96ee5df2e5555cce18cbe2a7d693e82 (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
/* vi: set sw=4 ts=4: */
/*
 * Mini less implementation for busybox
 *
 *
 * Copyright (C) 2005 by Rob Sullivan <cogito.ergo.cogito@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
 * 02111-1307 USA
 *
 *	This program needs a lot of development, so consider it in a beta stage
 *	at best.
 *
 *	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.
 *	- Check for binary files, and prompt the user if a binary file
 *	is detected.
 *	- Allow horizontal scrolling. Currently, lines simply continue onto
 *	the next line, per the terminal's discretion
 *
 *	Notes:
 *	- filename is an array and not a pointer because that avoids all sorts
 *	of complications involving the fact that something that is pointed to
 *	will be changed if the pointer is changed.
 *	- the inp file pointer is used so that keyboard input works after
 *	redirected input has been read from stdin
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include <ctype.h>

#include "busybox.h"

#ifdef CONFIG_FEATURE_LESS_REGEXP
#include "xregex.h"
#endif


/* These are the escape sequences corresponding to special keys */
#define REAL_KEY_UP 'A'
#define REAL_KEY_DOWN 'B'
#define REAL_KEY_RIGHT 'C'
#define REAL_KEY_LEFT 'D'
#define REAL_PAGE_UP '5'
#define REAL_PAGE_DOWN '6'

/* These are the special codes assigned by this program to the special keys */
#define PAGE_UP 20
#define PAGE_DOWN 21
#define KEY_UP 22
#define KEY_DOWN 23
#define KEY_RIGHT 24
#define KEY_LEFT 25

/* The escape codes for highlighted and normal text */
#define HIGHLIGHT "\033[7m"
#define NORMAL "\033[0m"

/* The escape code to clear the screen */
#define CLEAR "\033[2J"

/* Maximum number of lines in a file */
#define MAXLINES 10000

/* Get height and width of terminal */
#define tty_width_height()              get_terminal_width_height(0, &width, &height)

static int height;
static int width;
static char **files;
static char filename[256];
static char buffer[100][256];
static char *flines[MAXLINES];
static int current_file = 1;
static int line_pos;
static int num_flines;
static int num_files = 1;
static int past_eof;

/* Command line options */
static int E_FLAG;
static int M_FLAG;
static int N_FLAG;
static int m_FLAG;
static int TILDE_FLAG;

/* This is needed so that program behaviour changes when input comes from
   stdin */
static int inp_stdin;
/* This is required so that when a file is requested to be examined after
   input has come from stdin (e.g. dmesg | less), the input stream from
   the keyboard still stays the same. If it switched back to stdin, keyboard
   input wouldn't work. */
static int ea_inp_stdin;

#ifdef CONFIG_FEATURE_LESS_MARKS
static int mark_lines[15][2];
static int num_marks;
#endif

#ifdef CONFIG_FEATURE_LESS_REGEXP
static int match_found;
static int match_lines[100];
static int match_pos;
static int num_matches;
static int match_backwards;
static int num_back_match = 1;
#endif

/* Needed termios structures */
static struct termios term_orig, term_vi;

/* File pointer to get input from */
static FILE *inp;

/* Reset terminal input to normal */
static void set_tty_cooked(void) {
	fflush(stdout);
	tcsetattr(0, TCSANOW, &term_orig);
}

/* Set terminal input to raw mode */
static void set_tty_raw(void) {
       tcgetattr(0, &term_orig);
	term_vi = term_orig;
	term_vi.c_lflag &= (~ICANON & ~ECHO);
	term_vi.c_iflag &= (~IXON & ~ICRNL);
	term_vi.c_oflag &= (~ONLCR);
	term_vi.c_cc[VMIN] = 1;
	term_vi.c_cc[VTIME] = 0;
	tcsetattr(0, TCSANOW, &term_vi);
}

/* Exit the program gracefully */
static void tless_exit(int code) {

	/* TODO: We really should save the terminal state when we start,
		 and restore it when we exit. Less does this with the
		 "ti" and "te" termcap commands; can this be done with
		 only termios.h? */

	putchar('\n');
	exit(code);
}

/* Grab a character from input without requiring the return key. If the
   character is ASCII \033, get more characters and assign certain sequences
   special return codes. Note that this function works best with raw input. */
static int tless_getch(void) {

	set_tty_raw();
	char input_key[3];

	input_key[0] = getc(inp);
	/* Detect escape sequences (i.e. arrow keys) and handle
	   them accordingly */

	if (input_key[0] == '\033') {
		input_key[1] = getc(inp);
		input_key[2] = getc(inp);
		set_tty_cooked();
		if (input_key[1] == '[') {
			if (input_key[2] == REAL_KEY_UP)
				return KEY_UP;
			else if (input_key[2] == REAL_KEY_DOWN)
				return KEY_DOWN;
			else if (input_key[2] == REAL_KEY_RIGHT)
				return KEY_RIGHT;
			else if (input_key[2] == REAL_KEY_LEFT)
				return KEY_LEFT;
			else if (input_key[2] == REAL_PAGE_UP)
				return PAGE_UP;
			else if (input_key[2] == REAL_PAGE_DOWN)
				return PAGE_DOWN;
		}
	}
	/* The input is a normal ASCII value */
	else {
		set_tty_cooked();
		return input_key[0];
	}
	return 0;
}

/* Move the cursor to a position (x,y), where (0,0) is the
   top-left corner of the console */
static void move_cursor(int x, int y) {
	printf("\033[%i;%iH", x, y);
}

static void clear_line(void) {
	move_cursor(height, 0);
	printf("\033[K");
}

/* This adds line numbers to every line, as the -N flag necessitates */
static void add_linenumbers(void) {

	char current_line[256];
	int i;

	for (i = 0; i <= num_flines; i++) {
		safe_strncpy(current_line, flines[i], 256);
		flines[i] = xrealloc(flines[i], strlen(current_line) + 7 );
		sprintf(flines[i],"%5d %s", i+1, current_line);
	}
}

static void data_readlines(void) {

	int i;
	char current_line[256];
	FILE *fp;

	fp = (inp_stdin) ? stdin : bb_xfopen(filename, "rt");

	for (i = 0; (!feof(fp)) && (i <= MAXLINES); i++) {
		strcpy(current_line, "");
		fgets(current_line, 256, fp);
		bb_xferror(fp, filename);
		flines[i] = (char *) bb_xstrndup(current_line, (strlen(current_line) + 1) * sizeof(char));
	}
	num_flines = i - 2;

/* Reset variables for a new file */

	line_pos = 0;
	past_eof = 0;

	fclose(fp);

	if (inp_stdin)
		inp = fopen(CURRENT_TTY, "r");
	else
		inp = stdin;

	if (ea_inp_stdin) {
		fclose(inp);
		inp = fopen(CURRENT_TTY, "r");
	}

	if (N_FLAG)
		add_linenumbers();
}

/* Free the file data */
static void free_flines(void) {

	int i;

	for (i = 0; i <= num_flines; i++)
		free(flines[i]);
}

#ifdef CONFIG_FEATURE_LESS_FLAGS
/* Calculate the percentage the current line position is through the file */
static int calc_percent(void) {
	return ((100 * (line_pos + height - 2) / num_flines) + 1);
}
#endif

/* Turn a percentage into a line number */
static int reverse_percent(int percentage) {
	double linenum = percentage;
	linenum = ((linenum / 100) * num_flines) - 1;
	return(linenum);
}

#ifdef CONFIG_FEATURE_LESS_FLAGS
/* Print a status line if -M was specified */
static void m_status_print(void) {

	int percentage;

	if (!past_eof) {
		if (!line_pos) {
			if (num_files > 1)
				printf("%s%s %s%i%s%i%s%i-%i/%i ", HIGHLIGHT, filename, "(file ", current_file, " of ", num_files, ") lines ", line_pos + 1, line_pos + height - 1, num_flines + 1);
			else {
				printf("%s%s lines %i-%i/%i ", HIGHLIGHT, filename, line_pos + 1, line_pos + height - 1, num_flines + 1);
			}
		}
		else {
			printf("%s %s lines %i-%i/%i ", HIGHLIGHT, filename, line_pos + 1, line_pos + height - 1, num_flines + 1);
		}

		if (line_pos == num_flines - height + 2) {
			printf("(END) %s", NORMAL);
			if ((num_files > 1) && (current_file != num_files))
				printf("%s- Next: %s%s", HIGHLIGHT, files[current_file], NORMAL);
		}
		else {
			percentage = calc_percent();
			printf("%i%s %s", percentage, "%", NORMAL);
		}
	}
	else {
		printf("%s%s lines %i-%i/%i (END) ", HIGHLIGHT, filename, line_pos + 1, num_flines + 1, num_flines + 1);
		if ((num_files > 1) && (current_file != num_files))
			printf("- Next: %s", files[current_file]);
		printf("%s", NORMAL);
	}
}

/* Print a status line if -m was specified */
static void medium_status_print(void) {

	int percentage;
	percentage = calc_percent();

	if (!line_pos)
		printf("%s%s %i%s%s", HIGHLIGHT, filename, percentage, "%", NORMAL);
	else if (line_pos == num_flines - height + 2)
		printf("%s(END)%s", HIGHLIGHT, NORMAL);
	else
		printf("%s%i%s%s", HIGHLIGHT, percentage, "%", NORMAL);
}
#endif

/* Print the status line */
static void status_print(void) {

	/* Change the status if flags have been set */
#ifdef CONFIG_FEATURE_LESS_FLAGS
	if (M_FLAG)
		m_status_print();
	else if (m_FLAG)
		medium_status_print();
	/* No flags set */
	else {
#endif
		if (!line_pos) {
			printf("%s%s %s", HIGHLIGHT, filename, NORMAL);
			if (num_files > 1)
				printf("%s%s%i%s%i%s%s", HIGHLIGHT, "(file ", current_file, " of ", num_files, ")", NORMAL);
		}
		else if (line_pos == num_flines - height + 2) {
			printf("%s%s %s", HIGHLIGHT, "(END)", NORMAL);
			if ((num_files > 1) && (current_file != num_files))
				printf("%s%s%s%s", HIGHLIGHT, "- Next: ", files[current_file], NORMAL);
		}
		else {
			printf("%c", ':');
		}
#ifdef CONFIG_FEATURE_LESS_FLAGS
	}
#endif
}

/* Print the buffer */
static void buffer_print(void) {

	int i;

	if (num_flines >= height - 2) {
		printf("%s", CLEAR);
		move_cursor(0,0);
		for (i = 0; i < height - 1; i++)
			printf("%s", buffer[i]);
		status_print();
	}
	else {
		printf("%s", CLEAR);
		move_cursor(0,0);
		for (i = 1; i < (height - 1 - num_flines); i++)
			putchar('\n');
		for (i = 0; i < height - 1; i++)
			printf("%s", buffer[i]);
		status_print();
	}
}

/* Initialise the buffer */
static void buffer_init(void) {

	int i;

	for (i = 0; i < (height - 1); i++)
		memset(buffer[i], '\0', 256);

	/* Fill the buffer until the end of the file or the
	   end of the buffer is reached */
	for (i = 0; (i < (height - 1)) && (i <= num_flines); i++) {
		strcpy(buffer[i], flines[i]);
	}

	/* If the buffer still isn't full, fill it with blank lines */
	for (; i < (height - 1); i++) {
		strcpy(buffer[i], "");
	}
}

/* Move the buffer up and down in the file in order to scroll */
static void buffer_down(int nlines) {

	int i;

	if (!past_eof) {
		if (line_pos + (height - 3) + nlines < num_flines) {
			line_pos += nlines;
			for (i = 0; i < (height - 1); i++)
				strcpy(buffer[i], flines[line_pos + i]);
		}
		else {
			/* As the number of lines requested was too large, we just move
			to the end of the file */
			while (line_pos + (height - 3) + 1 < num_flines) {
				line_pos += 1;
				for (i = 0; i < (height - 1); i++)
					strcpy(buffer[i], flines[line_pos + i]);
			}
		}

		/* We exit if the -E flag has been set */
		if (E_FLAG && (line_pos + (height - 2) == num_flines))
			tless_exit(0);
	}
}

static void buffer_up(int nlines) {

	int i;
	int tilde_line;

	if (!past_eof) {
		if (line_pos - nlines >= 0) {
			line_pos -= nlines;
			for (i = 0; i < (height - 1); i++)
				strcpy(buffer[i], flines[line_pos + i]);
		}
		else {
		/* As the requested number of lines to move was too large, we
		   move one line up at a time until we can't. */
			while (line_pos != 0) {
				line_pos -= 1;
				for (i = 0; i < (height - 1); i++)
					strcpy(buffer[i], flines[line_pos + i]);
			}
		}
	}
	else {
		/* Work out where the tildes start */
		tilde_line = num_flines - line_pos + 3;

		line_pos -= nlines;
		/* Going backwards nlines lines has taken us to a point where
		   nothing is past the EOF, so we revert to normal. */
		if (line_pos < num_flines - height + 3) {
			past_eof = 0;
			buffer_up(nlines);
		}
		else {
			/* We only move part of the buffer, as the rest
			is past the EOF */
			for (i = 0; i < (height - 1); i++) {
				if (i < tilde_line - nlines + 1)
					strcpy(buffer[i], flines[line_pos + i]);
				else {
					if (line_pos >= num_flines - height + 2)
						strcpy(buffer[i], "~\n");
				}
			}
		}
	}
}

static void buffer_line(int linenum) {

	int i;

	past_eof = 0;

	if (linenum < 1 || linenum > num_flines) {
		clear_line();
		printf("%s%s%i%s", HIGHLIGHT, "Cannot seek to line number ", linenum, NORMAL);
	}
	else if (linenum < (num_flines - height - 2)) {
		for (i = 0; i < (height - 1); i++)
			strcpy(buffer[i], flines[linenum + i]);
		line_pos = linenum;
	}
	else {
		for (i = 0; i < (height - 1); i++) {
			if (linenum + i < num_flines + 2)
				strcpy(buffer[i], flines[linenum + i]);
			else
				strcpy(buffer[i], (TILDE_FLAG) ? "\n" : "~\n");
		}
		line_pos = linenum;
		/* Set past_eof so buffer_down and buffer_up act differently */
		past_eof = 1;
	}
}

static void examine_file(void) {

	int newline_offset;

	clear_line();
	printf("Examine: ");
	fgets(filename, 256, inp);

	/* As fgets adds a newline to the end of an input string, we
	   need to remove it */
	newline_offset = strlen(filename) - 1;
	filename[newline_offset] = '\0';

	files[num_files] = bb_xstrndup(filename, (strlen(filename) + 1) * sizeof(char));
	current_file = num_files + 1;
	num_files++;

	inp_stdin = 0;
	ea_inp_stdin = 1;
	free_flines();
	data_readlines();
	buffer_init();
	buffer_print();
}


static void next_file(void) {
	if (current_file != num_files) {
		current_file++;
		strcpy(filename, files[current_file - 1]);
		free_flines();
		data_readlines();
		buffer_init();
		buffer_print();
	}
	else {
		clear_line();
		printf("%s%s%s", HIGHLIGHT, "No next file", NORMAL);
	}
}

static void previous_file(void) {
	if (current_file != 1) {
		current_file--;
		strcpy(filename, files[current_file - 1]);

		free_flines();
		data_readlines();
		buffer_init();
		buffer_print();
	}
	else {
		clear_line();
		printf("%s%s%s", HIGHLIGHT, "No previous file", NORMAL);
	}
}

static void first_file(void) {
	if (current_file != 1) {
		current_file = 1;
		strcpy(filename, files[current_file - 1]);
		free_flines();
		data_readlines();
		buffer_init();
		buffer_print();
	}
}

static void remove_current_file(void) {

	int i;

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

static void colon_process(void) {

	int keypress;

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

	keypress = tless_getch();
	switch (keypress) {
		case 'd':
			remove_current_file();
			break;
		case 'e':
			examine_file();
			break;
#ifdef CONFIG_FEATURE_LESS_FLAGS
		case 'f':
			clear_line();
			m_status_print();
			break;
#endif
		case 'n':
			next_file();
			break;
		case 'p':
			previous_file();
			break;
		case 'q':
			tless_exit(0);
			break;
		case 'x':
			first_file();
			break;
		default:
			break;
	}
}

#ifdef CONFIG_FEATURE_LESS_REGEXP
/* The below two regular expression handler functions NEED development. */

/* Get a regular expression from the user, and then go through the current
   file line by line, running a processing regex function on each one. */

static char *insert_highlights (char *line, int start, int end) {

	char *new_line = (char *) malloc((sizeof(char) * (strlen(line) + 1)) + 10);

	memset(new_line, 0, ((sizeof(char) * (strlen(line) + 1)) + 10));
	strncat(new_line, line, start);
	strcat(new_line, HIGHLIGHT);
	strncat(new_line, line + start, end - start);
	strcat(new_line, NORMAL);
	strncat(new_line, line + end, strlen(line) - end);

	return new_line;
}

static char *process_regex_on_line(char *line, regex_t *pattern) {
	/* This function takes the regex and applies it to the line.
	   Each part of the line that matches has the HIGHLIGHT
	   and NORMAL escape sequences placed around it by
	   insert_highlights, and then the line is returned. */

	int match_status;
	char *line2 = (char *) malloc((sizeof(char) * (strlen(line) + 1)) + 64);
	char sub_line[256];
	int prev_eo = 0;
	regmatch_t match_structs;
	
	memset(sub_line, 0, 256);
	strcpy(line2, line);

	match_found = 0;
	match_status = regexec(pattern, line2, 1, &match_structs, 0);

	while (match_status == 0) {

		memset(sub_line, 0, 256);

		if (match_found == 0)
			match_found = 1;

		line2 = insert_highlights(line2, match_structs.rm_so + prev_eo, match_structs.rm_eo + prev_eo);
		if (match_structs.rm_eo + 11 + prev_eo < strlen(line2))
			strcat(sub_line, line2 + match_structs.rm_eo + 11 + prev_eo);

		prev_eo += match_structs.rm_eo + 11;
		match_status = regexec(pattern, sub_line, 1, &match_structs, REG_NOTBOL);
	}

	return line2;
}

static void regex_process(void) {

	char uncomp_regex[100];
	char current_line[256];
	int i;
	int j = 0;
	regex_t *pattern;

	/* Reset variables */
	match_lines[0] = -1;
	match_pos = 0;
	num_matches = 0;
	match_found = 0;

	pattern = (regex_t *) malloc(sizeof(regex_t));
	memset(pattern, 0, sizeof(regex_t));

	/* Get the uncompiled regular expression from the user */
	clear_line();
	if (match_backwards)
		printf("?");
	else
		printf("/");
	scanf("%s", uncomp_regex);

	/* Compile the regex and check for errors */
	xregcomp(pattern, uncomp_regex, 0);

	/* Run the regex on each line of the current file here */
	for (i = 0; i <= num_flines; i++) {
		strcpy(current_line, process_regex_on_line(flines[i], pattern));
		flines[i] = (char *) bb_xstrndup(current_line, sizeof(char) * (strlen(current_line)+1));

		if (match_found) {
			match_lines[j] = i;
			j++;
		}
	}

	num_matches = j;

	if ((match_lines[0] != -1) && (num_flines > height - 2))
		buffer_line(match_lines[0]);
	else
		buffer_init();
}

static void goto_match(int match) {

	/* This goes to a specific match - all line positions of matches are
	   stored within the match_lines[] array. */
	if ((match < num_matches) && (match >= 0)) {
		buffer_line(match_lines[match]);
		match_pos = match;
	}
}

static void search_backwards(void) {

	int current_linepos = line_pos;
	int i;

	match_backwards = 1;
	regex_process();

	for (i = 0; i < num_matches; i++) {
		if (match_lines[i] > current_linepos) {
			buffer_line(match_lines[i - num_back_match]);
			break;
		}
	}

	/* Reset variables */
	match_backwards = 0;
	num_back_match = 1;

}
#endif

static void number_process(int first_digit) {

	int i = 1;
	int num;
	char num_input[80];
	char keypress;
	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 */
	while((num_input[i] = tless_getch()) && isdigit(num_input[i])) {
		printf("%c",num_input[i]);
		i++;
	}

	/* Take the final letter out of the digits string */
	keypress = num_input[i];
	num_input[i] = '\0';
	i--;
	num = atoi(num_input);

	/* We now know the number and the letter entered, so we process them */
	switch (keypress) {
		case KEY_DOWN: case 'z': case 'd': case 'e': case ' ': case '\015':
			buffer_down(num);
			buffer_print();
			break;
		case KEY_UP: case 'b': case 'w': case 'y': case 'u':
			buffer_up(num);
			buffer_print();
			break;
		case 'g': case '<': case 'G': case '>':
			if (num_flines >= height - 2)
				buffer_line(num - 1);
			buffer_print();
			break;
		case 'p': case '%':
			buffer_line(reverse_percent(num));
			buffer_print();
			break;
#ifdef CONFIG_FEATURE_LESS_REGEXP
		case 'n':
			goto_match(match_pos + num - 1);
			buffer_print();
			break;
		case '/':
			regex_process();
			goto_match(num - 1);
			buffer_print();
			break;
		case '?':
			num_back_match = num;
			search_backwards();
			buffer_print();
			break;
#endif
		default:
			break;
	}
}

#ifdef CONFIG_FEATURE_LESS_FLAGCS
static void flag_change(void) {

	int keypress;

	clear_line();
	printf("-");
	keypress = tless_getch();

	switch (keypress) {
		case 'M':
			M_FLAG = !M_FLAG;
			break;
		case 'm':
			m_FLAG = !m_FLAG;
			break;
		case 'E':
			E_FLAG = !E_FLAG;
			break;
		case '~':
			TILDE_FLAG = !TILDE_FLAG;
			break;
		default:
			break;
	}
}

static void show_flag_status(void) {

	int keypress;
	int flag_val;

	clear_line();
	printf("_");
	keypress = tless_getch();

	switch (keypress) {
		case 'M':
			flag_val = M_FLAG;
			break;
		case 'm':
			flag_val = m_FLAG;
			break;
		case '~':
			flag_val = TILDE_FLAG;
			break;
		case 'N':
			flag_val = N_FLAG;
			break;
		case 'E':
			flag_val = E_FLAG;
			break;
		default:
			flag_val = 0;
			break;
	}

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

static void full_repaint(void) {

	int temp_line_pos = line_pos;
	data_readlines();
	buffer_init();
	buffer_line(temp_line_pos);
	buffer_print();
}


static void save_input_to_file(void) {

	char current_line[256];
	int i;
	FILE *fp;

	clear_line();
	printf("Log file: ");
	fgets(current_line, 256, inp);
	current_line[strlen(current_line) - 1] = '\0';
	if (strlen(current_line)) {
		fp = bb_xfopen(current_line, "w");
		for (i = 0; i < num_flines; i++)
			fprintf(fp, "%s", flines[i]);
		fclose(fp);
		buffer_print();
	}
	else
		printf("%sNo log file%s", HIGHLIGHT, NORMAL);
}

#ifdef CONFIG_FEATURE_LESS_MARKS
static void add_mark(void) {

	int letter;
	int mark_line;

	clear_line();
	printf("Mark: ");
	letter = tless_getch();

	if (isalpha(letter)) {
		mark_line = line_pos;

		/* 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] = line_pos;
		num_marks++;
	}
	else {
		clear_line();
		printf("%s%s%s", HIGHLIGHT, "Invalid mark letter", NORMAL);
	}
}

static void goto_mark(void) {

	int letter;
	int i;

	clear_line();
	printf("Go to mark: ");
	letter = tless_getch();
	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])) {
			clear_line();
			printf("%s%s%s", HIGHLIGHT, "Mark not set", NORMAL);
		}
	}
	else {
		clear_line();
		printf("%s%s%s", HIGHLIGHT, "Invalid mark letter", NORMAL);
	}
}
#endif


#ifdef CONFIG_FEATURE_LESS_BRACKETS

static char opp_bracket (char bracket) {

	switch (bracket) {
		case '{': case '[':
			return bracket + 2;
			break;
		case '(':
			return ')';
			break;
		case '}': case ']':
			return bracket - 2;
			break;
		case ')':
			return '(';
			break;
		default:
			return 0;
			break;
	}
}

static void match_right_bracket(char bracket) {

	int bracket_line = -1;
	int i;

	if (strchr(flines[line_pos], bracket) == NULL) {
		clear_line();
		printf("%s%s%s", HIGHLIGHT, "No bracket in top line", NORMAL);
	}
	else {
		for (i = line_pos + 1; i < num_flines; i++) {
			if (strchr(flines[i], opp_bracket(bracket)) != NULL) {
				bracket_line = i;
				break;
			}
		}

		if (bracket_line == -1) {
			clear_line();
			printf("%s%s%s", HIGHLIGHT, "No matching bracket found", NORMAL);
		}

		buffer_line(bracket_line - height + 2);
		buffer_print();
	}
}

static void match_left_bracket (char bracket) {

	int bracket_line = -1;
	int i;

	if (strchr(flines[line_pos + height - 2], bracket) == NULL) {
		clear_line();
		printf("%s%s%s", HIGHLIGHT, "No bracket in bottom line", NORMAL);
		printf("%s", flines[line_pos + height]);
		sleep(4);
	}
	else {
		for (i = line_pos + height - 2; i >= 0; i--) {
			if (strchr(flines[i], opp_bracket(bracket)) != NULL) {
				bracket_line = i;
				break;
			}
		}

		if (bracket_line == -1) {
			clear_line();
			printf("%s%s%s", HIGHLIGHT, "No matching bracket found", NORMAL);
		}

		buffer_line(bracket_line);
		buffer_print();
	}
}

#endif  /* CONFIG_FEATURE_LESS_BRACKETS */

static void keypress_process(int keypress) {
	switch (keypress) {
		case KEY_DOWN: case 'e': case 'j': case '\015':
			buffer_down(1);
			buffer_print();
			break;
		case KEY_UP: case 'y': case 'k':
			buffer_up(1);
			buffer_print();
			break;
		case PAGE_DOWN: case ' ': case 'z':
			buffer_down(height - 1);
			buffer_print();
			break;
		case PAGE_UP: case 'w': case 'b':
			buffer_up(height - 1);
			buffer_print();
			break;
		case 'd':
			buffer_down((height - 1) / 2);
			buffer_print();
			break;
		case 'u':
			buffer_up((height - 1) / 2);
			buffer_print();
			break;
		case 'g': case 'p': case '<': case '%':
			buffer_up(num_flines + 1);
			buffer_print();
			break;
		case 'G': case '>':
			buffer_down(num_flines + 1);
			buffer_print();
			break;
		case 'q': case 'Q':
			tless_exit(0);
			break;
#ifdef CONFIG_FEATURE_LESS_MARKS
		case 'm':
			add_mark();
			buffer_print();
			break;
		case '\'':
			goto_mark();
			buffer_print();
			break;
#endif
		case 'r':
			buffer_print();
			break;
		case 'R':
			full_repaint();
			break;
		case 's':
			if (inp_stdin)
				save_input_to_file();
			break;
		case 'E':
			examine_file();
			break;
#ifdef CONFIG_FEATURE_LESS_FLAGS
		case '=':
			clear_line();
			m_status_print();
			break;
#endif
#ifdef CONFIG_FEATURE_LESS_REGEXP
		case '/':
			regex_process();
			buffer_print();
			break;
		case 'n':
			goto_match(match_pos + 1);
			buffer_print();
			break;
		case 'N':
			goto_match(match_pos - 1);
			buffer_print();
			break;
		case '?':
			search_backwards();
			buffer_print();
			break;
#endif
#ifdef CONFIG_FEATURE_LESS_FLAGCS
		case '-':
			flag_change();
			buffer_print();
			break;
		case '_':
			show_flag_status();
			break;
#endif
#ifdef CONFIG_FEATURE_LESS_BRACKETS
		case '{': case '(': case '[':
			match_right_bracket(keypress);
			break;
		case '}': case ')': case ']':
			match_left_bracket(keypress);
			break;
#endif
		case ':':
			colon_process();
			break;
		default:
			break;
	}
	if (isdigit(keypress))
		number_process(keypress);
}

int less_main(int argc, char **argv) {

	unsigned long flags;
	int keypress;

	flags =  bb_getopt_ulflags(argc, argv, "EMNm~");
	E_FLAG = (flags & 1);
	M_FLAG = (flags & 2);
	N_FLAG = (flags & 4);
	m_FLAG = (flags & 8);
	TILDE_FLAG = (flags & 16);

	argc -= optind;
	argv += optind;
	files = argv;
	num_files = argc;

	if (!num_files) {
		if (ttyname(STDIN_FILENO) == NULL)
			inp_stdin = 1;
		else {
			bb_error_msg("Missing filename");
			bb_show_usage();
		}
	}

	strcpy(filename, (inp_stdin) ? "stdin" : files[0]);
	tty_width_height();
	data_readlines();
	buffer_init();
	buffer_print();

	while (1) {
		keypress = tless_getch();
		keypress_process(keypress);
	}
}