summaryrefslogtreecommitdiff
path: root/editors/sed.c
blob: 229a9feaaa086fe98a06a6c05c1e62c88b3d1299 (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
/* vi: set sw=4 ts=4: */
/*
 * sed.c - very minimalist version of sed
 *
 * Copyright (C) 1999,2000,2001 by Lineo, inc. and Mark Whitley
 * Copyright (C) 1999,2000,2001 by Mark Whitley <markw@codepoet.org>
 * Copyright (C) 2002  Matt Kraai
 * Copyright (C) 2003 by Glenn McGrath <bug1@iinet.net.au>
 * Copyright (C) 2003,2004 by Rob Landley <rob@landley.net>
 *
 * MAINTAINER: Rob Landley <rob@landley.net>
 *
 * Licensed under GPL version 2, see file LICENSE in this tarball for details.
 */

/* Code overview.

  Files are laid out to avoid unnecessary function declarations.  So for
  example, every function add_cmd calls occurs before add_cmd in this file.

  add_cmd() is called on each line of sed command text (from a file or from
  the command line).  It calls get_address() and parse_cmd_args().  The
  resulting sed_cmd_t structures are appended to a linked list
  (bbg.sed_cmd_head/bbg.sed_cmd_tail).

  add_input_file() adds a FILE * to the list of input files.  We need to
  know all input sources ahead of time to find the last line for the $ match.

  process_files() does actual sedding, reading data lines from each input FILE *
  (which could be stdin) and applying the sed command list (sed_cmd_head) to
  each of the resulting lines.

  sed_main() is where external code calls into this, with a command line.
*/


/*
	Supported features and commands in this version of sed:

	 - comments ('#')
	 - address matching: num|/matchstr/[,num|/matchstr/|$]command
	 - commands: (p)rint, (d)elete, (s)ubstitue (with g & I flags)
	 - edit commands: (a)ppend, (i)nsert, (c)hange
	 - file commands: (r)ead
	 - backreferences in substitution expressions (\0, \1, \2...\9)
	 - grouped commands: {cmd1;cmd2}
	 - transliteration (y/source-chars/dest-chars/)
	 - pattern space hold space storing / swapping (g, h, x)
	 - labels / branching (: label, b, t, T)

	 (Note: Specifying an address (range) to match is *optional*; commands
	 default to the whole pattern space if no specific address match was
	 requested.)

	Todo:
	 - Create a wrapper around regex to make libc's regex conform with sed

	Reference http://www.opengroup.org/onlinepubs/007904975/utilities/sed.html
*/

#include "busybox.h"
#include "xregex.h"

/* Each sed command turns into one of these structures. */
typedef struct sed_cmd_s {
    /* Ordered by alignment requirements: currently 36 bytes on x86 */

    /* address storage */
    regex_t *beg_match;	/* sed -e '/match/cmd' */
    regex_t *end_match;	/* sed -e '/match/,/end_match/cmd' */
    regex_t *sub_match;	/* For 's/sub_match/string/' */
    int beg_line;		/* 'sed 1p'   0 == apply commands to all lines */
    int end_line;		/* 'sed 1,3p' 0 == one line only. -1 = last line ($) */

    FILE *file;			/* File (sw) command writes to, -1 for none. */
    char *string;		/* Data string for (saicytb) commands. */

    unsigned short which_match;		/* (s) Which match to replace (0 for all) */

    /* Bitfields (gcc won't group them if we don't) */
    unsigned int invert:1;			/* the '!' after the address */
    unsigned int in_match:1;		/* Next line also included in match? */
    unsigned int no_newline:1;		/* Last line written by (sw) had no '\n' */
    unsigned int sub_p:1;			/* (s) print option */

    /* GENERAL FIELDS */
    char cmd;				/* The command char: abcdDgGhHilnNpPqrstwxy:={} */
    struct sed_cmd_s *next;	/* Next command (linked list, NULL terminated) */
} sed_cmd_t;

static const char *const semicolon_whitespace = "; \n\r\t\v";

struct sed_globals
{
	/* options */
	int be_quiet, in_place, regex_type;
	FILE *nonstdout;
	char *outname, *hold_space;

	/* List of input files */
	int input_file_count,current_input_file;
	FILE **input_file_list;

	regmatch_t regmatch[10];
	regex_t *previous_regex_ptr;

	/* linked list of sed commands */
	sed_cmd_t sed_cmd_head, *sed_cmd_tail;

	/* Linked list of append lines */
	llist_t *append_head;

	char *add_cmd_line;

	struct pipeline {
		char *buf;	/* Space to hold string */
		int idx;	/* Space used */
		int len;	/* Space allocated */
	} pipeline;
} bbg;


void sed_free_and_close_stuff(void);
#if ENABLE_FEATURE_CLEAN_UP
void sed_free_and_close_stuff(void)
{
	sed_cmd_t *sed_cmd = bbg.sed_cmd_head.next;

	llist_free(bbg.append_head, free);

	while (sed_cmd) {
		sed_cmd_t *sed_cmd_next = sed_cmd->next;

		if(sed_cmd->file)
			xprint_and_close_file(sed_cmd->file);

		if (sed_cmd->beg_match) {
			regfree(sed_cmd->beg_match);
			free(sed_cmd->beg_match);
		}
		if (sed_cmd->end_match) {
			regfree(sed_cmd->end_match);
			free(sed_cmd->end_match);
		}
		if (sed_cmd->sub_match) {
			regfree(sed_cmd->sub_match);
			free(sed_cmd->sub_match);
		}
		free(sed_cmd->string);
		free(sed_cmd);
		sed_cmd = sed_cmd_next;
	}

	if(bbg.hold_space) free(bbg.hold_space);

    while(bbg.current_input_file<bbg.input_file_count)
		fclose(bbg.input_file_list[bbg.current_input_file++]);
}
#endif

/* If something bad happens during -i operation, delete temp file */

static void cleanup_outname(void)
{
  if(bbg.outname) unlink(bbg.outname);
}

/* strdup, replacing "\n" with '\n', and "\delimiter" with 'delimiter' */

static void parse_escapes(char *dest, char *string, int len, char from, char to)
{
	int i=0;

	while(i<len) {
		if(string[i] == '\\') {
			if(!to || string[i+1] == from) {
				*(dest++) = to ? to : string[i+1];
				i+=2;
				continue;
			} else *(dest++)=string[i++];
		}
		*(dest++) = string[i++];
	}
	*dest=0;
}

static char *copy_parsing_escapes(char *string, int len)
{
	char *dest=xmalloc(len+1);

	parse_escapes(dest,string,len,'n','\n');
	return dest;
}


/*
 * index_of_next_unescaped_regexp_delim - walks left to right through a string
 * beginning at a specified index and returns the index of the next regular
 * expression delimiter (typically a forward * slash ('/')) not preceded by
 * a backslash ('\').  A negative delimiter disables square bracket checking.
 */
static int index_of_next_unescaped_regexp_delim(int delimiter, char *str)
{
	int bracket = -1;
	int escaped = 0;
	int idx = 0;
	char ch;

	if (delimiter < 0) {
		bracket--;
		delimiter *= -1;
	}

	for (; (ch = str[idx]); idx++) {
		if (bracket >= 0) {
			if (ch == ']' && !(bracket == idx - 1 || (bracket == idx - 2
					&& str[idx - 1] == '^')))
				bracket = -1;
		} else if (escaped)
			escaped = 0;
		else if (ch == '\\')
			escaped = 1;
		else if (bracket == -1 && ch == '[')
			bracket = idx;
		else if (ch == delimiter)
			return idx;
	}

	/* if we make it to here, we've hit the end of the string */
	bb_error_msg_and_die("unmatched '%c'",delimiter);
}

/*
 *  Returns the index of the third delimiter
 */
static int parse_regex_delim(char *cmdstr, char **match, char **replace)
{
	char *cmdstr_ptr = cmdstr;
	char delimiter;
	int idx = 0;

	/* verify that the 's' or 'y' is followed by something.  That something
	 * (typically a 'slash') is now our regexp delimiter... */
	if (*cmdstr == '\0')
		bb_error_msg_and_die("bad format in substitution expression");
	delimiter = *(cmdstr_ptr++);

	/* save the match string */
	idx = index_of_next_unescaped_regexp_delim(delimiter, cmdstr_ptr);
	*match = copy_parsing_escapes(cmdstr_ptr, idx);

	/* save the replacement string */
	cmdstr_ptr += idx + 1;
	idx = index_of_next_unescaped_regexp_delim(-delimiter, cmdstr_ptr);
	*replace = copy_parsing_escapes(cmdstr_ptr, idx);

	return ((cmdstr_ptr - cmdstr) + idx);
}

/*
 * returns the index in the string just past where the address ends.
 */
static int get_address(char *my_str, int *linenum, regex_t ** regex)
{
	char *pos = my_str;

	if (isdigit(*my_str)) {
		*linenum = strtol(my_str, &pos, 10);
		/* endstr shouldnt ever equal NULL */
	} else if (*my_str == '$') {
		*linenum = -1;
		pos++;
	} else if (*my_str == '/' || *my_str == '\\') {
		int next;
		char delimiter;
		char *temp;

		if (*my_str == '\\') delimiter = *(++pos);
		else delimiter = '/';
		next = index_of_next_unescaped_regexp_delim(delimiter, ++pos);
		temp = copy_parsing_escapes(pos,next);
		*regex = (regex_t *) xmalloc(sizeof(regex_t));
		xregcomp(*regex, temp, bbg.regex_type|REG_NEWLINE);
		free(temp);
		/* Move position to next character after last delimiter */
		pos += (next+1);
	}
	return pos - my_str;
}

/* Grab a filename.  Whitespace at start is skipped, then goes to EOL. */
static int parse_file_cmd(sed_cmd_t *sed_cmd, char *filecmdstr, char **retval)
{
	int start = 0, idx, hack=0;

	/* Skip whitespace, then grab filename to end of line */
	while (isspace(filecmdstr[start])) start++;
	idx=start;
	while(filecmdstr[idx] && filecmdstr[idx]!='\n') idx++;
	/* If lines glued together, put backslash back. */
	if(filecmdstr[idx]=='\n') hack=1;
	if(idx==start) bb_error_msg_and_die("Empty filename");
	*retval = xstrndup(filecmdstr+start, idx-start+hack+1);
	if(hack) *(idx+*retval)='\\';

	return idx;
}

static int parse_subst_cmd(sed_cmd_t *sed_cmd, char *substr)
{
	int cflags = bbg.regex_type;
	char *match;
	int idx = 0;

	/*
	 * A substitution command should look something like this:
	 *    s/match/replace/ #gIpw
	 *    ||     |        |||
	 *    mandatory       optional
	 */
	idx = parse_regex_delim(substr, &match, &sed_cmd->string);

	/* determine the number of back references in the match string */
	/* Note: we compute this here rather than in the do_subst_command()
	 * function to save processor time, at the expense of a little more memory
	 * (4 bits) per sed_cmd */

	/* process the flags */

	sed_cmd->which_match=1;
	while (substr[++idx]) {
		/* Parse match number */
		if(isdigit(substr[idx])) {
			if(match[0]!='^') {
				/* Match 0 treated as all, multiple matches we take the last one. */
				char *pos=substr+idx;
				sed_cmd->which_match=(unsigned short)strtol(substr+idx,&pos,10);
				idx=pos-substr;
			}
			continue;
		}
		/* Skip spaces */
		if(isspace(substr[idx])) continue;

		switch (substr[idx]) {
			/* Replace all occurrences */
			case 'g':
				if (match[0] != '^') sed_cmd->which_match = 0;
				break;
			/* Print pattern space */
			case 'p':
				sed_cmd->sub_p = 1;
				break;
			/* Write to file */
			case 'w':
			{
				char *temp;
				idx+=parse_file_cmd(sed_cmd,substr+idx,&temp);

				break;
			}
			/* Ignore case (gnu exension) */
			case 'I':
				cflags |= REG_ICASE;
				break;
			/* Comment */
			case '#':
				while(substr[++idx]);
				/* Fall through */
			/* End of command */
			case ';':
			case '}':
				goto out;
			default:
				bb_error_msg_and_die("bad option in substitution expression");
		}
	}
out:
	/* compile the match string into a regex */
	if (*match != '\0') {
		/* If match is empty, we use last regex used at runtime */
		sed_cmd->sub_match = (regex_t *) xmalloc(sizeof(regex_t));
		xregcomp(sed_cmd->sub_match, match, cflags);
	}
	free(match);

	return idx;
}

/*
 *  Process the commands arguments
 */
static char *parse_cmd_args(sed_cmd_t *sed_cmd, char *cmdstr)
{
	/* handle (s)ubstitution command */
	if (sed_cmd->cmd == 's') cmdstr += parse_subst_cmd(sed_cmd, cmdstr);
	/* handle edit cmds: (a)ppend, (i)nsert, and (c)hange */
	else if (strchr("aic", sed_cmd->cmd)) {
		if ((sed_cmd->end_line || sed_cmd->end_match) && sed_cmd->cmd != 'c')
			bb_error_msg_and_die
				("only a beginning address can be specified for edit commands");
		for(;;) {
			if(*cmdstr=='\n' || *cmdstr=='\\') {
				cmdstr++;
				break;
			} else if(isspace(*cmdstr)) cmdstr++;
			else break;
		}
		sed_cmd->string = xstrdup(cmdstr);
		parse_escapes(sed_cmd->string,sed_cmd->string,strlen(cmdstr),0,0);
		cmdstr += strlen(cmdstr);
	/* handle file cmds: (r)ead */
	} else if(strchr("rw", sed_cmd->cmd)) {
		if (sed_cmd->end_line || sed_cmd->end_match)
			bb_error_msg_and_die("Command only uses one address");
		cmdstr += parse_file_cmd(sed_cmd, cmdstr, &sed_cmd->string);
		if(sed_cmd->cmd=='w')
			sed_cmd->file=xfopen(sed_cmd->string,"w");
	/* handle branch commands */
	} else if (strchr(":btT", sed_cmd->cmd)) {
		int length;

		while(isspace(*cmdstr)) cmdstr++;
		length = strcspn(cmdstr, semicolon_whitespace);
		if (length) {
			sed_cmd->string = xstrndup(cmdstr, length);
			cmdstr += length;
		}
	}
	/* translation command */
	else if (sed_cmd->cmd == 'y') {
		char *match, *replace;
		int i=cmdstr[0];

		cmdstr+=parse_regex_delim(cmdstr, &match, &replace)+1;
		/* \n already parsed, but \delimiter needs unescaping. */
		parse_escapes(match,match,strlen(match),i,i);
		parse_escapes(replace,replace,strlen(replace),i,i);

		sed_cmd->string = xzalloc((strlen(match) + 1) * 2);
		for (i = 0; match[i] && replace[i]; i++) {
			sed_cmd->string[i * 2] = match[i];
			sed_cmd->string[(i * 2) + 1] = replace[i];
		}
		free(match);
		free(replace);
	}
	/* if it wasnt a single-letter command that takes no arguments
	 * then it must be an invalid command.
	 */
	else if (strchr("dDgGhHlnNpPqx={}", sed_cmd->cmd) == 0) {
		bb_error_msg_and_die("Unsupported command %c", sed_cmd->cmd);
	}

	/* give back whatever's left over */
	return (cmdstr);
}


/* Parse address+command sets, skipping comment lines. */

static void add_cmd(char *cmdstr)
{
	sed_cmd_t *sed_cmd;
	int temp;

	/* Append this line to any unfinished line from last time. */
	if (bbg.add_cmd_line) {
		cmdstr = xasprintf("%s\n%s", bbg.add_cmd_line, cmdstr);
		free(bbg.add_cmd_line);
		bbg.add_cmd_line = cmdstr;
	}

	/* If this line ends with backslash, request next line. */
	temp=strlen(cmdstr);
	if(temp && cmdstr[temp-1]=='\\') {
		if (!bbg.add_cmd_line) bbg.add_cmd_line = xstrdup(cmdstr);
		bbg.add_cmd_line[temp-1] = 0;
		return;
	}

	/* Loop parsing all commands in this line. */
	while(*cmdstr) {
		/* Skip leading whitespace and semicolons */
		cmdstr += strspn(cmdstr, semicolon_whitespace);

		/* If no more commands, exit. */
		if(!*cmdstr) break;

		/* if this is a comment, jump past it and keep going */
		if (*cmdstr == '#') {
			/* "#n" is the same as using -n on the command line */
			if (cmdstr[1] == 'n') bbg.be_quiet++;
			if(!(cmdstr=strpbrk(cmdstr, "\n\r"))) break;
			continue;
		}

		/* parse the command
		 * format is: [addr][,addr][!]cmd
		 *            |----||-----||-|
		 *            part1 part2  part3
		 */

		sed_cmd = xzalloc(sizeof(sed_cmd_t));

		/* first part (if present) is an address: either a '$', a number or a /regex/ */
		cmdstr += get_address(cmdstr, &sed_cmd->beg_line, &sed_cmd->beg_match);

		/* second part (if present) will begin with a comma */
		if (*cmdstr == ',') {
			int idx;

			cmdstr++;
			idx = get_address(cmdstr, &sed_cmd->end_line, &sed_cmd->end_match);
			if (!idx) bb_error_msg_and_die("no address after comma");
			cmdstr += idx;
		}

		/* skip whitespace before the command */
		while (isspace(*cmdstr)) cmdstr++;

		/* Check for inversion flag */
		if (*cmdstr == '!') {
			sed_cmd->invert = 1;
			cmdstr++;

			/* skip whitespace before the command */
			while (isspace(*cmdstr)) cmdstr++;
		}

		/* last part (mandatory) will be a command */
		if (!*cmdstr) bb_error_msg_and_die("missing command");
		sed_cmd->cmd = *(cmdstr++);
		cmdstr = parse_cmd_args(sed_cmd, cmdstr);

		/* Add the command to the command array */
		bbg.sed_cmd_tail->next = sed_cmd;
		bbg.sed_cmd_tail = bbg.sed_cmd_tail->next;
	}

	/* If we glued multiple lines together, free the memory. */
	free(bbg.add_cmd_line);
	bbg.add_cmd_line = NULL;
}

/* Append to a string, reallocating memory as necessary. */

#define PIPE_GROW 64

static void pipe_putc(char c)
{
	if(bbg.pipeline.idx==bbg.pipeline.len) {
		bbg.pipeline.buf = xrealloc(bbg.pipeline.buf,
								bbg.pipeline.len + PIPE_GROW);
		bbg.pipeline.len+=PIPE_GROW;
	}
	bbg.pipeline.buf[bbg.pipeline.idx++] = c;
}

static void do_subst_w_backrefs(char *line, char *replace)
{
	int i,j;

	/* go through the replacement string */
	for (i = 0; replace[i]; i++) {
		/* if we find a backreference (\1, \2, etc.) print the backref'ed * text */
		if (replace[i] == '\\' && replace[i+1]>='0' && replace[i+1]<='9') {
			int backref=replace[++i]-'0';

			/* print out the text held in bbg.regmatch[backref] */
			if(bbg.regmatch[backref].rm_so != -1)
				for (j = bbg.regmatch[backref].rm_so;
					j < bbg.regmatch[backref].rm_eo; j++) pipe_putc(line[j]);
		}

		/* if we find a backslash escaped character, print the character */
		else if (replace[i] == '\\') pipe_putc(replace[++i]);

		/* if we find an unescaped '&' print out the whole matched text. */
		else if (replace[i] == '&')
			for (j = bbg.regmatch[0].rm_so; j < bbg.regmatch[0].rm_eo; j++)
				pipe_putc(line[j]);
		/* Otherwise just output the character. */
		else pipe_putc(replace[i]);
	}
}

static int do_subst_command(sed_cmd_t *sed_cmd, char **line)
{
	char *oldline = *line;
	int altered = 0;
	int match_count=0;
	regex_t *current_regex;

	/* Handle empty regex. */
	if (sed_cmd->sub_match == NULL) {
		current_regex = bbg.previous_regex_ptr;
		if(!current_regex)
			bb_error_msg_and_die("No previous regexp.");
	} else bbg.previous_regex_ptr = current_regex = sed_cmd->sub_match;

	/* Find the first match */
	if(REG_NOMATCH==regexec(current_regex, oldline, 10, bbg.regmatch, 0))
		return 0;

	/* Initialize temporary output buffer. */
	bbg.pipeline.buf=xmalloc(PIPE_GROW);
	bbg.pipeline.len=PIPE_GROW;
	bbg.pipeline.idx=0;

	/* Now loop through, substituting for matches */
	do {
		int i;

		/* Work around bug in glibc regexec, demonstrated by:
		   echo " a.b" | busybox sed 's [^ .]* x g'
		   The match_count check is so not to break
		   echo "hi" | busybox sed 's/^/!/g' */
		if(!bbg.regmatch[0].rm_so && !bbg.regmatch[0].rm_eo && match_count) {
			pipe_putc(*(oldline++));
			continue;
		}

		match_count++;

		/* If we aren't interested in this match, output old line to
		   end of match and continue */
		if(sed_cmd->which_match && sed_cmd->which_match!=match_count) {
			for(i=0;i<bbg.regmatch[0].rm_eo;i++)
				pipe_putc(*(oldline++));
			continue;
		}

		/* print everything before the match */
		for (i = 0; i < bbg.regmatch[0].rm_so; i++) pipe_putc(oldline[i]);

		/* then print the substitution string */
		do_subst_w_backrefs(oldline, sed_cmd->string);

		/* advance past the match */
		oldline += bbg.regmatch[0].rm_eo;
		/* flag that something has changed */
		altered++;

		/* if we're not doing this globally, get out now */
		if (sed_cmd->which_match) break;
	} while (*oldline && (regexec(current_regex, oldline, 10, bbg.regmatch, 0) != REG_NOMATCH));

	/* Copy rest of string into output pipeline */

	while(*oldline) pipe_putc(*(oldline++));
	pipe_putc(0);

	free(*line);
	*line = bbg.pipeline.buf;
	return altered;
}

/* Set command pointer to point to this label.  (Does not handle null label.) */
static sed_cmd_t *branch_to(char *label)
{
	sed_cmd_t *sed_cmd;

	for (sed_cmd = bbg.sed_cmd_head.next; sed_cmd; sed_cmd = sed_cmd->next) {
		if ((sed_cmd->cmd == ':') && (sed_cmd->string) && (strcmp(sed_cmd->string, label) == 0)) {
			return (sed_cmd);
		}
	}
	bb_error_msg_and_die("Can't find label for jump to `%s'", label);
}

static void append(char *s)
{
	llist_add_to_end(&bbg.append_head, xstrdup(s));
}

static void flush_append(void)
{
	char *data;

	/* Output appended lines. */
	while((data = (char *)llist_pop(&bbg.append_head))) {
		fprintf(bbg.nonstdout,"%s\n",data);
		free(data);
	}
}

static void add_input_file(FILE *file)
{
	bbg.input_file_list=xrealloc(bbg.input_file_list,
			(bbg.input_file_count + 1) * sizeof(FILE *));
	bbg.input_file_list[bbg.input_file_count++] = file;
}

/* Get next line of input from bbg.input_file_list, flushing append buffer and
 * noting if we ran out of files without a newline on the last line we read.
 */
static char *get_next_line(int *no_newline)
{
	char *temp=NULL;
	int len;

	flush_append();
	while (bbg.current_input_file<bbg.input_file_count) {
		temp = bb_get_chunk_from_file(bbg.input_file_list[bbg.current_input_file],&len);
		if (temp) {
			*no_newline = !(len && temp[len-1]=='\n');
			if (!*no_newline) temp[len-1] = 0;
			break;
		// Close this file and advance to next one
		} else fclose(bbg.input_file_list[bbg.current_input_file++]);
	}

	return temp;
}

/* Output line of text.  missing_newline means the last line output did not
   end with a newline.  no_newline means this line does not end with a
   newline. */

static int puts_maybe_newline(char *s, FILE *file, int missing_newline, int no_newline)
{
	if(missing_newline) fputc('\n',file);
	fputs(s,file);
	if(!no_newline) fputc('\n',file);

    if(ferror(file)) {
		bb_default_error_retval = 4;  /* It's what gnu sed exits with... */
		bb_error_msg_and_die(bb_msg_write_error);
	}

	return no_newline;
}

#define sed_puts(s,n) missing_newline=puts_maybe_newline(s,bbg.nonstdout,missing_newline,n)

/* Process all the lines in all the files */

static void process_files(void)
{
	char *pattern_space, *next_line;
	int linenum = 0, missing_newline=0;
	int no_newline,next_no_newline=0;

	/* Prime the pump */
	next_line = get_next_line(&next_no_newline);

	/* go through every line in each file */
	for(;;) {
		sed_cmd_t *sed_cmd;
		int substituted=0;

		/* Advance to next line.  Stop if out of lines. */
		if(!(pattern_space=next_line)) break;
		no_newline=next_no_newline;

		/* Read one line in advance so we can act on the last line,
		 * the '$' address */
		next_line = get_next_line(&next_no_newline);
		linenum++;
restart:
		/* for every line, go through all the commands */
		for (sed_cmd = bbg.sed_cmd_head.next; sed_cmd; sed_cmd = sed_cmd->next)
		{
			int old_matched, matched;

			old_matched = sed_cmd->in_match;

			/* Determine if this command matches this line: */

			/* Are we continuing a previous multi-line match? */

			sed_cmd->in_match = sed_cmd->in_match

			/* Or is no range necessary? */
				|| (!sed_cmd->beg_line && !sed_cmd->end_line
					&& !sed_cmd->beg_match && !sed_cmd->end_match)

			/* Or did we match the start of a numerical range? */
				|| (sed_cmd->beg_line > 0 && (sed_cmd->beg_line == linenum))

			/* Or does this line match our begin address regex? */
				|| (sed_cmd->beg_match &&
				    !regexec(sed_cmd->beg_match, pattern_space, 0, NULL, 0))

			/* Or did we match last line of input? */
				|| (sed_cmd->beg_line == -1 && next_line == NULL);

			/* Snapshot the value */

			matched = sed_cmd->in_match;

			/* Is this line the end of the current match? */

			if(matched) {
				sed_cmd->in_match = !(
					/* has the ending line come, or is this a single address command? */
					(sed_cmd->end_line ?
						sed_cmd->end_line==-1 ?
							!next_line
							: sed_cmd->end_line<=linenum
						: !sed_cmd->end_match)
					/* or does this line matches our last address regex */
					|| (sed_cmd->end_match && old_matched && (regexec(sed_cmd->end_match, pattern_space, 0, NULL, 0) == 0))
				);
			}

			/* Skip blocks of commands we didn't match. */
			if (sed_cmd->cmd == '{') {
				if(sed_cmd->invert ? matched : !matched)
					while(sed_cmd && sed_cmd->cmd!='}') sed_cmd=sed_cmd->next;
				if(!sed_cmd) bb_error_msg_and_die("Unterminated {");
				continue;
			}

			/* Okay, so did this line match? */
			if (sed_cmd->invert ? !matched : matched) {
				/* Update last used regex in case a blank substitute BRE is found */
				if (sed_cmd->beg_match) {
					bbg.previous_regex_ptr = sed_cmd->beg_match;
				}

				/* actual sedding */
				switch (sed_cmd->cmd) {

					/* Print line number */
					case '=':
						fprintf(bbg.nonstdout,"%d\n", linenum);
						break;

					/* Write the current pattern space up to the first newline */
					case 'P':
					{
						char *tmp = strchr(pattern_space, '\n');

						if (tmp) {
							*tmp = '\0';
							sed_puts(pattern_space,1);
							*tmp = '\n';
							break;
						}
						/* Fall Through */
					}

					/* Write the current pattern space to output */
					case 'p':
						sed_puts(pattern_space,no_newline);
						break;
					/* Delete up through first newline */
					case 'D':
					{
						char *tmp = strchr(pattern_space,'\n');

						if(tmp) {
							tmp=xstrdup(tmp+1);
							free(pattern_space);
							pattern_space=tmp;
							goto restart;
						}
					}
					/* discard this line. */
					case 'd':
						goto discard_line;

					/* Substitute with regex */
					case 's':
						if(do_subst_command(sed_cmd, &pattern_space)) {
							substituted|=1;

							/* handle p option */
							if(sed_cmd->sub_p)
								sed_puts(pattern_space,no_newline);
							/* handle w option */
							if(sed_cmd->file)
								sed_cmd->no_newline=puts_maybe_newline(pattern_space, sed_cmd->file, sed_cmd->no_newline, no_newline);

						}
						break;

					/* Append line to linked list to be printed later */
					case 'a':
					{
						append(sed_cmd->string);
						break;
					}

					/* Insert text before this line */
					case 'i':
						sed_puts(sed_cmd->string,1);
						break;

					/* Cut and paste text (replace) */
					case 'c':
						/* Only triggers on last line of a matching range. */
						if (!sed_cmd->in_match) sed_puts(sed_cmd->string,0);
						goto discard_line;

					/* Read file, append contents to output */
					case 'r':
					{
						FILE *rfile;

						rfile = fopen(sed_cmd->string, "r");
						if (rfile) {
							char *line;

							while ((line = bb_get_chomped_line_from_file(rfile))
									!= NULL)
								append(line);
							xprint_and_close_file(rfile);
						}

						break;
					}

					/* Write pattern space to file. */
					case 'w':
						sed_cmd->no_newline=puts_maybe_newline(pattern_space,sed_cmd->file, sed_cmd->no_newline,no_newline);
						break;

					/* Read next line from input */
					case 'n':
						if (!bbg.be_quiet)
							sed_puts(pattern_space,no_newline);
						if (next_line) {
							free(pattern_space);
							pattern_space = next_line;
							no_newline=next_no_newline;
							next_line = get_next_line(&next_no_newline);
							linenum++;
							break;
						}
						/* fall through */

					/* Quit.  End of script, end of input. */
					case 'q':
						/* Exit the outer while loop */
						free(next_line);
						next_line = NULL;
						goto discard_commands;

					/* Append the next line to the current line */
					case 'N':
					{
						/* If no next line, jump to end of script and exit. */
						if (next_line == NULL) {
							/* Jump to end of script and exit */
							free(next_line);
							next_line = NULL;
							goto discard_line;
						/* append next_line, read new next_line. */
						} else {
							int len=strlen(pattern_space);

							pattern_space = realloc(pattern_space, len + strlen(next_line) + 2);
							pattern_space[len]='\n';
							strcpy(pattern_space+len+1, next_line);
							no_newline=next_no_newline;
							next_line = get_next_line(&next_no_newline);
							linenum++;
						}
						break;
					}

					/* Test/branch if substitution occurred */
					case 't':
						if(!substituted) break;
						substituted=0;
						/* Fall through */
					/* Test/branch if substitution didn't occur */
					case 'T':
						if (substituted) break;
						/* Fall through */
					/* Branch to label */
					case 'b':
						if (!sed_cmd->string) goto discard_commands;
						else sed_cmd = branch_to(sed_cmd->string);
						break;
					/* Transliterate characters */
					case 'y':
					{
						int i;

						for (i = 0; pattern_space[i]; i++) {
							int j;

							for (j = 0; sed_cmd->string[j]; j += 2) {
								if (pattern_space[i] == sed_cmd->string[j]) {
									pattern_space[i] = sed_cmd->string[j + 1];
									break;
								}
							}
						}

						break;
					}
					case 'g':	/* Replace pattern space with hold space */
						free(pattern_space);
						pattern_space = xstrdup(bbg.hold_space ? bbg.hold_space : "");
						break;
					case 'G':	/* Append newline and hold space to pattern space */
					{
						int pattern_space_size = 2;
						int hold_space_size = 0;

						if (pattern_space)
							pattern_space_size += strlen(pattern_space);
						if (bbg.hold_space)
							hold_space_size = strlen(bbg.hold_space);
						pattern_space = xrealloc(pattern_space,
								pattern_space_size + hold_space_size);
						if (pattern_space_size == 2) pattern_space[0]=0;
						strcat(pattern_space, "\n");
						if (bbg.hold_space)
							strcat(pattern_space, bbg.hold_space);
						no_newline=0;

						break;
					}
					case 'h':	/* Replace hold space with pattern space */
						free(bbg.hold_space);
						bbg.hold_space = xstrdup(pattern_space);
						break;
					case 'H':	/* Append newline and pattern space to hold space */
					{
						int hold_space_size = 2;
						int pattern_space_size = 0;

						if (bbg.hold_space)
							hold_space_size += strlen(bbg.hold_space);
						if (pattern_space)
							pattern_space_size = strlen(pattern_space);
						bbg.hold_space = xrealloc(bbg.hold_space,
											hold_space_size + pattern_space_size);

						if (hold_space_size == 2) *bbg.hold_space=0;
						strcat(bbg.hold_space, "\n");
						if (pattern_space) strcat(bbg.hold_space, pattern_space);

						break;
					}
					case 'x': /* Exchange hold and pattern space */
					{
						char *tmp = pattern_space;
						pattern_space = bbg.hold_space ? : xzalloc(1);
						no_newline=0;
						bbg.hold_space = tmp;
						break;
					}
				}
			}
		}

		/*
		 * exit point from sedding...
		 */
discard_commands:
		/* we will print the line unless we were told to be quiet ('-n')
		   or if the line was suppressed (ala 'd'elete) */
		if (!bbg.be_quiet) sed_puts(pattern_space,no_newline);

		/* Delete and such jump here. */
discard_line:
		flush_append();
		free(pattern_space);
	}
}

/* It is possible to have a command line argument with embedded
   newlines.  This counts as multiple command lines. */

static void add_cmd_block(char *cmdstr)
{
	int go=1;
	char *temp=xstrdup(cmdstr),*temp2=temp;

	while(go) {
		int len=strcspn(temp2,"\n");
		if(!temp2[len]) go=0;
		else temp2[len]=0;
		add_cmd(temp2);
		temp2+=len+1;
	}
	free(temp);
}

int sed_main(int argc, char **argv)
{
	unsigned long opt;
	llist_t *opt_e, *opt_f;
	int status = EXIT_SUCCESS;

	bbg.sed_cmd_tail=&bbg.sed_cmd_head;

	/* destroy command strings on exit */
	if (ENABLE_FEATURE_CLEAN_UP) atexit(sed_free_and_close_stuff);

	/* Lie to autoconf when it starts asking stupid questions. */
	if(argc==2 && !strcmp(argv[1],"--version")) {
		printf("This is not GNU sed version 4.0\n");
		exit(0);
	}

	/* do normal option parsing */
	opt_e = opt_f = NULL;
	bb_opt_complementally = "e::f::"; /* can occur multiple times */
	opt = bb_getopt_ulflags(argc, argv, "irne:f:", &opt_e, &opt_f);
	if (opt & 0x1) { // -i
		bbg.in_place++;
		atexit(cleanup_outname);
	}
	if (opt & 0x2) bbg.regex_type|=REG_EXTENDED; // -r
	if (opt & 0x4) bbg.be_quiet++; // -n
	if (opt & 0x8) { // -e
		while (opt_e) {
			llist_t *cur = opt_e;
			add_cmd_block(cur->data);
			opt_e = cur->link;
			free(cur);
		}
	}
	if (opt & 0x10) { // -f
		while (opt_f) {
			llist_t *cur = opt_f;
			FILE *cmdfile;
			char *line;
			cmdfile = xfopen(cur->data, "r");
			while ((line = bb_get_chomped_line_from_file(cmdfile)) != NULL) {
				add_cmd(line);
				free(line);
			}
			xprint_and_close_file(cmdfile);
			opt_f = cur->link;
			free(cur);
		}
	}
	/* if we didn't get a pattern from -e or -f, use argv[optind] */
	if(!(opt & 0x18)) {
		if (argv[optind] == NULL)
			bb_show_usage();
		else
			add_cmd_block(argv[optind++]);
	}
	/* Flush any unfinished commands. */
	add_cmd("");

	/* By default, we write to stdout */
	bbg.nonstdout = stdout;

	/* argv[(optind)..(argc-1)] should be names of file to process. If no
	 * files were specified or '-' was specified, take input from stdin.
	 * Otherwise, we process all the files specified. */
	if (argv[optind] == NULL) {
		if(bbg.in_place) bb_error_msg_and_die(bb_msg_requires_arg, "-i");
		add_input_file(stdin);
		process_files();
	} else {
		int i;
		FILE *file;

		for (i = optind; i < argc; i++) {
			if(!strcmp(argv[i], "-") && !bbg.in_place) {
				add_input_file(stdin);
				process_files();
			} else {
				file = bb_wfopen(argv[i], "r");
				if (file) {
					if(bbg.in_place) {
						struct stat statbuf;
						int nonstdoutfd;

						bbg.outname=xstrndup(argv[i],strlen(argv[i])+6);
						strcat(bbg.outname,"XXXXXX");
						if(-1==(nonstdoutfd=mkstemp(bbg.outname)))
							bb_error_msg_and_die("no temp file");
						bbg.nonstdout=fdopen(nonstdoutfd,"w");

						/* Set permissions of output file */

						fstat(fileno(file),&statbuf);
						fchmod(nonstdoutfd,statbuf.st_mode);
						add_input_file(file);
						process_files();
						fclose(bbg.nonstdout);

						bbg.nonstdout=stdout;
						unlink(argv[i]);
						rename(bbg.outname,argv[i]);
						free(bbg.outname);
						bbg.outname=0;
					} else add_input_file(file);
				} else {
					status = EXIT_FAILURE;
				}
			}
		}
		if(bbg.input_file_count>bbg.current_input_file) process_files();
	}

	return status;
}