aboutsummaryrefslogtreecommitdiffstats
path: root/wiretap/file_wrappers.c
blob: 443bd5ce6daf988970c87709f6d598be9637717d (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
/* file_wrappers.c
 *
 * $Id$
 *
 * Wiretap Library
 * Copyright (c) 1998 by Gilbert Ramirez <gram@alumni.rice.edu>
 *
 * 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.
 */

/* file_access interface based heavily on zlib gzread.c and gzlib.c from zlib
 * Copyright (C) 1995-2010 Jean-loup Gailly and Mark Adler
 * under licence:
 *
 *  This software is provided 'as-is', without any express or implied
 *  warranty.  In no event will the authors be held liable for any damages
 *  arising from the use of this software.
 *
 *  Permission is granted to anyone to use this software for any purpose,
 *  including commercial applications, and to alter it and redistribute it
 *  freely, subject to the following restrictions:
 *
 *  1. The origin of this software must not be misrepresented; you must not
 *     claim that you wrote the original software. If you use this software
 *     in a product, an acknowledgment in the product documentation would be
 *     appreciated but is not required.
 *  2. Altered source versions must be plainly marked as such, and must not be
 *     misrepresented as being the original software.
 *  3. This notice may not be removed or altered from any source distribution.
*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif /* HAVE_UNISTD_H */

#include <errno.h>
#include <stdio.h>
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif /* HAVE_FCNTL_H */
#include <string.h>
#include "wtap-int.h"
#include "file_wrappers.h"
#include <wsutil/file_util.h>

#ifdef HAVE_LIBZ
#include <zlib.h>
#endif /* HAVE_LIBZ */

/*
 * See RFC 1952 for a description of the gzip file format.
 *
 * Some other compressed file formats we might want to support:
 *
 *	XZ format: http://tukaani.org/xz/
 *
 *	Bzip2 format: http://bzip.org/
 */

/*
 * List of extensions for compressed files.
 * If we add support for more compressed file types, this table
 * might be expanded to include routines to handle the various
 * compression types.
 */
static const char *compressed_file_extensions[] = {
#ifdef HAVE_LIBZ
	"gz",
#endif
	NULL
};

/*
 * Return a GSList of all the compressed file extensions.
 * The data pointers all point to items in compressed_file_extensions[],
 * so the GSList can just be freed with g_slist_free().
 */
GSList *
wtap_get_compressed_file_extensions(void)
{
	const char **extension;
	GSList *extensions;

	extensions = NULL;
	for (extension = &compressed_file_extensions[0]; *extension != NULL;
	    extension++)
		extensions = g_slist_append(extensions, (gpointer)(*extension));
	return extensions;
}

/* #define GZBUFSIZE 8192 */
#define GZBUFSIZE 4096

struct wtap_reader {
	int fd;                 /* file descriptor */
	gint64 raw_pos;         /* current position in file (just to not call lseek()) */
	gint64 pos;             /* current position in uncompressed data */
	unsigned size;          /* buffer size */
	unsigned char *in;      /* input buffer */
	unsigned char *out;     /* output buffer (double-sized when reading) */
	unsigned char *next;    /* next output data to deliver or write */

	unsigned have;          /* amount of output data unused at next */
	int eof;                /* true if end of input file reached */
	gint64 start;           /* where the gzip data started, for rewinding */
	gint64 raw;             /* where the raw data started, for seeking */
	int compression;        /* 0: ?, 1: uncompressed, 2: zlib */
	gboolean is_compressed; /* FALSE if completely uncompressed, TRUE otherwise */
	/* seek request */
	gint64 skip;            /* amount to skip (already rewound if backwards) */
	int seek;               /* true if seek request pending */
	/* error information */
	int err;                /* error code */
	const char *err_info;   /* additional error information string for some errors */

	unsigned int  avail_in; /* number of bytes available at next_in */
	unsigned char *next_in; /* next input byte */
#ifdef HAVE_LIBZ
	/* zlib inflate stream */
	z_stream strm;          /* stream structure in-place (not a pointer) */
	int dont_check_crc;	/* 1 if we aren't supposed to check the CRC */
#endif
	/* fast seeking */
	GPtrArray *fast_seek;
	void *fast_seek_cur;
};

/* values for wtap_reader compression */
#define UNKNOWN		0	/* look for a gzip header */
#define UNCOMPRESSED	1	/* copy input directly */
#ifdef HAVE_LIBZ
#define ZLIB		2	/* decompress a zlib stream */
#define GZIP_AFTER_HEADER 3
#endif

static int	/* gz_load */
raw_read(FILE_T state, unsigned char *buf, unsigned int count, unsigned *have)
{
	int ret;

	*have = 0;
	do {
		ret = read(state->fd, buf + *have, count - *have);
		if (ret <= 0)
			break;
		*have += ret;
		state->raw_pos += ret;
	} while (*have < count);
	if (ret < 0) {
		state->err = errno;
		state->err_info = NULL;
		return -1;
	}
	if (ret == 0)
		state->eof = 1;
	return 0;
}

static int /* gz_avail */
fill_in_buffer(FILE_T state)
{
	if (state->err)
		return -1;
	if (state->eof == 0) {
		if (raw_read(state, state->in, state->size, (unsigned *)&(state->avail_in)) == -1)
			return -1;
		state->next_in = state->in;
	}
	return 0;
}

#define ZLIB_WINSIZE 32768

struct fast_seek_point {
	gint64 out; 	/* corresponding offset in uncompressed data */
	gint64 in;		/* offset in input file of first full byte */

	int compression;
	union {
		struct {
#ifdef HAVE_INFLATEPRIME
			int bits;		/* number of bits (1-7) from byte at in - 1, or 0 */
#endif
			unsigned char window[ZLIB_WINSIZE];	/* preceding 32K of uncompressed data */

			/* be gentle with Z_STREAM_END, 8 bytes more... Another solution would be to comment checks out */
			guint32 adler;
			guint32 total_out;
		} zlib;
	} data;
};

struct zlib_cur_seek_point {
	unsigned char window[ZLIB_WINSIZE];	/* preceding 32K of uncompressed data */
	unsigned int pos;
	unsigned int have;
};

#define SPAN G_GINT64_CONSTANT(1048576)
static struct fast_seek_point *
fast_seek_find(FILE_T file, gint64 pos)
{
	struct fast_seek_point *smallest = NULL;
	struct fast_seek_point *item;
	guint low, i, max;

	if (!file->fast_seek)
		return NULL;

	for (low = 0, max = file->fast_seek->len; low < max; ) {
		i = (low + max) / 2;
		item = (struct fast_seek_point *)file->fast_seek->pdata[i];

		if (pos < item->out)
			max = i;
		else if (pos > item->out) {
			smallest = item;
			low = i + 1;
		} else {
			return item;
		}
	}
	return smallest;
}

static void
fast_seek_header(FILE_T file, gint64 in_pos, gint64 out_pos, int compression)
{
	struct fast_seek_point *item = NULL;

	if (file->fast_seek->len != 0)
		item = (struct fast_seek_point *)file->fast_seek->pdata[file->fast_seek->len - 1];

	if (!item || item->out < out_pos) {
		struct fast_seek_point *val = g_new(struct fast_seek_point,1);
		val->in = in_pos;
		val->out = out_pos;
		val->compression = compression;

		g_ptr_array_add(file->fast_seek, val);
	}
}

static void
fast_seek_reset(FILE_T state _U_)
{
#ifdef HAVE_LIBZ
	if (state->compression == ZLIB && state->fast_seek_cur) {
		struct zlib_cur_seek_point *cur = (struct zlib_cur_seek_point *) state->fast_seek_cur;

		cur->have = 0;
	}
#endif
}

#ifdef HAVE_LIBZ

/* Get next byte from input, or -1 if end or error.
 *
 * Note:
 *
 *	1) errors from raw_read(), and thus from fill_in_buffer(), are
 *	"sticky", and fill_in_buffer() won't do any reading if there's
 *	an error;
 *
 *	2) GZ_GETC() returns -1 on an EOF;
 *
 * so it's safe to make multiple GZ_GETC() calls and only check the
 * last one for an error. */
#define GZ_GETC() ((state->avail_in == 0 && fill_in_buffer(state) == -1) ? -1 : \
                (state->avail_in == 0 ? -1 : \
                 (state->avail_in--, *(state->next_in)++)))

/* Get a one-byte integer and return 0 on success and the value in *ret.
   Otherwise -1 is returned, state->err is set, and *ret is not modified. */
static int
gz_next1(FILE_T state, guint8 *ret)
{
	int ch;

	ch = GZ_GETC();
	if (ch == -1) {
		if (state->err == 0) {
			/* EOF */
			state->err = WTAP_ERR_SHORT_READ;
			state->err_info = NULL;
		}
		return -1;
	}
	*ret = ch;
	return 0;
}

/* Get a two-byte little-endian integer and return 0 on success and the value
   in *ret.  Otherwise -1 is returned, state->err is set, and *ret is not
   modified. */
static int
gz_next2(FILE_T state, guint16 *ret)
{
	guint16 val;
	int ch;

	val = GZ_GETC();
	ch = GZ_GETC();
	if (ch == -1) {
		if (state->err == 0) {
			/* EOF */
			state->err = WTAP_ERR_SHORT_READ;
			state->err_info = NULL;
		}
		return -1;
	}
	val += (guint16)ch << 8;
	*ret = val;
	return 0;
}

/* Get a four-byte little-endian integer and return 0 on success and the value
   in *ret.  Otherwise -1 is returned, state->err is set, and *ret is not
   modified. */
static int
gz_next4(FILE_T state, guint32 *ret)
{
	guint32 val;
	int ch;

	val = GZ_GETC();
	val += (unsigned)GZ_GETC() << 8;
	val += (guint32)GZ_GETC() << 16;
	ch = GZ_GETC();
	if (ch == -1) {
		if (state->err == 0) {
			/* EOF */
			state->err = WTAP_ERR_SHORT_READ;
			state->err_info = NULL;
		}
		return -1;
	}
	val += (guint32)ch << 24;
	*ret = val;
	return 0;
}

/* Skip the specified number of bytes and return 0 on success.  Otherwise -1
   is returned. */
static int
gz_skipn(FILE_T state, size_t n)
{
	while (n != 0) {
		if (GZ_GETC() == -1) {
			if (state->err == 0) {
				/* EOF */
				state->err = WTAP_ERR_SHORT_READ;
				state->err_info = NULL;
			}
			return -1;
		}
		n--;
	}
	return 0;
}

/* Skip a null-terminated string and return 0 on success.  Otherwise -1
   is returned. */
static int
gz_skipzstr(FILE_T state)
{
	int ch;

	/* It's null-terminated, so scan until we read a byte with
	   the value 0 or get an error. */
	while ((ch = GZ_GETC()) > 0)
		;
	if (ch == -1) {
		if (state->err == 0) {
			/* EOF */
			state->err = WTAP_ERR_SHORT_READ;
			state->err_info = NULL;
		}
		return -1;
	}
	return 0;
}

static void
zlib_fast_seek_add(FILE_T file, struct zlib_cur_seek_point *point, int bits, gint64 in_pos, gint64 out_pos)
{
	/* it's for sure after gzip header, so file->fast_seek->len != 0 */
	struct fast_seek_point *item = (struct fast_seek_point *)file->fast_seek->pdata[file->fast_seek->len - 1];

#ifndef HAVE_INFLATEPRIME
	if (bits)
		return;
#endif

	/* Glib has got Balanced Binary Trees (GTree) but I couldn't find a way to do quick search for nearest (and smaller) value to seek (It's what fast_seek_find() do)
	 *      Inserting value in middle of sorted array is expensive, so we want to add only in the end.
	 *      It's not big deal, cause first-read don't usually invoke seeking
	 */
	if (item->out + SPAN < out_pos) {
		struct fast_seek_point *val = g_new(struct fast_seek_point,1);
		val->in = in_pos;
		val->out = out_pos;
		val->compression = ZLIB;
#ifdef HAVE_INFLATEPRIME
		val->data.zlib.bits = bits;
#endif
		if (point->pos != 0) {
			unsigned int left = ZLIB_WINSIZE - point->pos;

			memcpy(val->data.zlib.window, point->window + point->pos, left);
			memcpy(val->data.zlib.window + left, point->window, point->pos);
		} else
			memcpy(val->data.zlib.window, point->window, ZLIB_WINSIZE);

		val->data.zlib.adler = file->strm.adler;
		val->data.zlib.total_out = file->strm.total_out;
		g_ptr_array_add(file->fast_seek, val);
	}
}

static void /* gz_decomp */
zlib_read(FILE_T state, unsigned char *buf, unsigned int count)
{
	int ret = 0;	/* XXX */
	guint32 crc, len;
	z_streamp strm = &(state->strm);

	unsigned char *buf2 = buf;
	unsigned int count2 = count;

	strm->avail_out = count;
	strm->next_out = buf;

	/* fill output buffer up to end of deflate stream or error */
	do {
		/* get more input for inflate() */
		if (state->avail_in == 0 && fill_in_buffer(state) == -1)
			break;
		if (state->avail_in == 0) {
			/* EOF */
			state->err = WTAP_ERR_SHORT_READ;
			state->err_info = NULL;
			break;
		}

		strm->avail_in = state->avail_in;
		strm->next_in = state->next_in;
		/* decompress and handle errors */
#ifdef Z_BLOCK
		ret = inflate(strm, Z_BLOCK);
#else
		ret = inflate(strm, Z_NO_FLUSH);
#endif
		state->avail_in = strm->avail_in;
		state->next_in = strm->next_in;
		if (ret == Z_STREAM_ERROR) {
			state->err = WTAP_ERR_DECOMPRESS;
			state->err_info = strm->msg;
			break;
		}
		if (ret == Z_NEED_DICT) {
			state->err = WTAP_ERR_DECOMPRESS;
			state->err_info = "preset dictionary needed";
			break;
		}
		if (ret == Z_MEM_ERROR) {
			/* This means "not enough memory". */
			state->err = ENOMEM;
			state->err_info = NULL;
			break;
		}
		if (ret == Z_DATA_ERROR) {              /* deflate stream invalid */
			state->err = WTAP_ERR_DECOMPRESS;
			state->err_info = strm->msg;
			break;
		}
		/*
		 * XXX - Z_BUF_ERROR?
		 */

		strm->adler = crc32(strm->adler, buf2, count2 - strm->avail_out);
#ifdef Z_BLOCK
		if (state->fast_seek_cur) {
			struct zlib_cur_seek_point *cur = (struct zlib_cur_seek_point *) state->fast_seek_cur;
			unsigned int ready = count2 - strm->avail_out;

			if (ready < ZLIB_WINSIZE) {
				unsigned left = ZLIB_WINSIZE - cur->pos;

				if (ready >= left) {
					memcpy(cur->window + cur->pos, buf2, left);
					if (ready != left)
						memcpy(cur->window, buf2 + left, ready - left);

					cur->pos = ready - left;
					cur->have += ready;
				} else {
					memcpy(cur->window + cur->pos, buf2, ready);
					cur->pos += ready;
					cur->have += ready;
				}

				if (cur->have >= ZLIB_WINSIZE)
					cur->have = ZLIB_WINSIZE;

			} else {
				memcpy(cur->window, buf2 + (ready - ZLIB_WINSIZE), ZLIB_WINSIZE);
				cur->pos = 0;
				cur->have = ZLIB_WINSIZE;
			}

			if (cur->have >= ZLIB_WINSIZE && ret != Z_STREAM_END && (strm->data_type & 128) && !(strm->data_type & 64))
				zlib_fast_seek_add(state, cur, (strm->data_type & 7), state->raw_pos - strm->avail_in, state->pos + (count - strm->avail_out));
		}
#endif
		buf2 = (buf2 + count2 - strm->avail_out);
		count2 = strm->avail_out;

	} while (strm->avail_out && ret != Z_STREAM_END);

	/* update available output and crc check value */
	state->next = buf;
	state->have = count - strm->avail_out;

	/* Check gzip trailer if at end of deflate stream.
	   We don't fail immediately here, we just set an error
	   indication, so that we try to process what data we
	   got before the error.  The next attempt to read
	   something past that data will get the error. */
	if (ret == Z_STREAM_END) {
		if (gz_next4(state, &crc) != -1 &&
		    gz_next4(state, &len) != -1) {
			if (crc != strm->adler && !state->dont_check_crc) {
				state->err = WTAP_ERR_DECOMPRESS;
				state->err_info = "bad CRC";
			} else if (len != (strm->total_out & 0xffffffffL)) {
				state->err = WTAP_ERR_DECOMPRESS;
				state->err_info = "length field wrong";
			}
		}
		state->compression = UNKNOWN;      /* ready for next stream, once have is 0 */
		g_free(state->fast_seek_cur);
		state->fast_seek_cur = NULL;
	}
}
#endif

static int
gz_head(FILE_T state)
{
	/* get some data in the input buffer */
	if (state->avail_in == 0) {
		if (fill_in_buffer(state) == -1)
			return -1;
		if (state->avail_in == 0)
			return 0;
	}

	/* look for the gzip magic header bytes 31 and 139 */
#ifdef HAVE_LIBZ
	if (state->next_in[0] == 31) {
		state->avail_in--;
		state->next_in++;
		if (state->avail_in == 0 && fill_in_buffer(state) == -1)
			return -1;
		if (state->avail_in && state->next_in[0] == 139) {
			guint8 cm;
			guint8 flags;
			guint16 len;
			guint16 hcrc;

			/* we have a gzip header, woo hoo! */
			state->avail_in--;
			state->next_in++;

			/* read rest of header */

			/* compression method (CM) */
			if (gz_next1(state, &cm) == -1)
				return -1;
			if (cm != 8) {
				state->err = WTAP_ERR_DECOMPRESS;
				state->err_info = "unknown compression method";
				return -1;
			}

			/* flags (FLG) */
			if (gz_next1(state, &flags) == -1)
				return -1;
			if (flags & 0xe0) {     /* reserved flag bits */
				state->err = WTAP_ERR_DECOMPRESS;
				state->err_info = "reserved flag bits set";
				return -1;
			}

			/* modification time (MTIME) */
			if (gz_skipn(state, 4) == -1)
				return -1;

			/* extra flags (XFL) */
			if (gz_skipn(state, 1) == -1)
				return -1;

			/* operating system (OS) */
			if (gz_skipn(state, 1) == -1)
				return -1;

			if (flags & 4) {
				/* extra field - get XLEN */
				if (gz_next2(state, &len) == -1)
					return -1;

				/* skip the extra field */
				if (gz_skipn(state, len) == -1)
					return -1;
			}
			if (flags & 8) {
				/* file name */
				if (gz_skipzstr(state) == -1)
					return -1;
			}
			if (flags & 16) {
				/* comment */
				if (gz_skipzstr(state) == -1)
					return -1;
			}
			if (flags & 2) {
				/* header crc */
				if (gz_next2(state, &hcrc) == -1)
					return -1;
				/* XXX - check the CRC? */
			}

			/* set up for decompression */
			inflateReset(&(state->strm));
			state->strm.adler = crc32(0L, Z_NULL, 0);
			state->compression = ZLIB;
			state->is_compressed = TRUE;
#ifdef Z_BLOCK
			if (state->fast_seek) {
				struct zlib_cur_seek_point *cur = g_new(struct zlib_cur_seek_point,1);

				cur->pos = cur->have = 0;
				g_free(state->fast_seek_cur);
				state->fast_seek_cur = cur;
				fast_seek_header(state, state->raw_pos - state->avail_in, state->pos, GZIP_AFTER_HEADER);
			}
#endif
			return 0;
		}
		else {
			/* not a gzip file -- save first byte (31) and fall to raw i/o */
			state->out[0] = 31;
			state->have = 1;
		}
	}
#endif
#ifdef HAVE_LIBXZ
	/* { 0xFD, '7', 'z', 'X', 'Z', 0x00 } */
	/* FD 37 7A 58 5A 00 */
#endif
	if (state->fast_seek)
		fast_seek_header(state, state->raw_pos - state->avail_in - state->have, state->pos, UNCOMPRESSED);

	/* doing raw i/o, save start of raw data for seeking, copy any leftover
	   input to output -- this assumes that the output buffer is larger than
	   the input buffer, which also assures space for gzungetc() */
	state->raw = state->pos;
	state->next = state->out;
	if (state->avail_in) {
		memcpy(state->next + state->have, state->next_in, state->avail_in);
		state->have += state->avail_in;
		state->avail_in = 0;
	}
	state->compression = UNCOMPRESSED;
	return 0;
}

static int /* gz_make */
fill_out_buffer(FILE_T state)
{
	if (state->compression == UNKNOWN) {           /* look for gzip header */
		if (gz_head(state) == -1)
			return -1;
		if (state->have)                /* got some data from gz_head() */
			return 0;
	}
	if (state->compression == UNCOMPRESSED) {           /* straight copy */
		if (raw_read(state, state->out, state->size /* << 1 */, &(state->have)) == -1)
			return -1;
		state->next = state->out;
	}
#ifdef HAVE_LIBZ
	else if (state->compression == ZLIB) {      /* decompress */
		zlib_read(state, state->out, state->size << 1);
	}
#endif
	return 0;
}

static int
gz_skip(FILE_T state, gint64 len)
{
	unsigned n;

	/* skip over len bytes or reach end-of-file, whichever comes first */
	while (len)
		if (state->have) {
			/* We have stuff in the output buffer; skip over
			   it. */
			n = (gint64)state->have > len ? (unsigned)len : state->have;
			state->have -= n;
			state->next += n;
			state->pos += n;
			len -= n;
		} else if (state->err) {
			/* We have nothing in the output buffer, and
			   we have an error that may not have been
			   reported yet; that means we can't generate
			   any more data into the output buffer, so
			   return an error indication. */
			return -1;
		} else if (state->eof && state->avail_in == 0) {
			/* We have nothing in the output buffer, and
			   we're at the end of the input; just return. */
			break;
		} else {
			/* We have nothing in the output buffer, and
			   we can generate more data; get more output,
			   looking for header if required. */
			if (fill_out_buffer(state) == -1)
				return -1;
		}
	return 0;
}

static void
gz_reset(FILE_T state)
{
	state->have = 0;              /* no output data available */
	state->eof = 0;               /* not at end of file */
	state->compression = UNKNOWN; /* look for gzip header */

	state->seek = 0;              /* no seek request pending */
	state->err = 0;               /* clear error */
	state->err_info = NULL;
	state->pos = 0;               /* no uncompressed data yet */
	state->avail_in = 0;          /* no input data yet */
}

FILE_T
file_fdopen(int fd)
{
#ifdef _STATBUF_ST_BLKSIZE	/* XXX, _STATBUF_ST_BLKSIZE portable? */
	struct stat st;
#endif
	int want = GZBUFSIZE;
	FILE_T state;

	if (fd == -1)
		return NULL;

	/* allocate FILE_T structure to return */
	state = (FILE_T)g_try_malloc(sizeof *state);
	if (state == NULL)
		return NULL;

	state->fast_seek_cur = NULL;
	state->fast_seek = NULL;

	/* open the file with the appropriate mode (or just use fd) */
	state->fd = fd;

	/* we don't yet know whether it's compressed */
	state->is_compressed = FALSE;

	/* save the current position for rewinding (only if reading) */
	state->start = ws_lseek64(state->fd, 0, SEEK_CUR);
	if (state->start == -1) state->start = 0;
	state->raw_pos = state->start;

	/* initialize stream */
	gz_reset(state);

#ifdef _STATBUF_ST_BLKSIZE
	if (fstat(fd, &st) >= 0) {
		want = st.st_blksize;
		/* XXX, verify result? */
	}
#endif

	/* allocate buffers */
	state->in = (unsigned char *)g_try_malloc(want);
	state->out = (unsigned char *)g_try_malloc(want << 1);
	state->size = want;
	if (state->in == NULL || state->out == NULL) {
		g_free(state->out);
		g_free(state->in);
		g_free(state);
		errno = ENOMEM;
		return NULL;
	}

#ifdef HAVE_LIBZ
	/* allocate inflate memory */
	state->strm.zalloc = Z_NULL;
	state->strm.zfree = Z_NULL;
	state->strm.opaque = Z_NULL;
	state->strm.avail_in = 0;
	state->strm.next_in = Z_NULL;
	if (inflateInit2(&(state->strm), -15) != Z_OK) {    /* raw inflate */
		g_free(state->out);
		g_free(state->in);
		g_free(state);
		errno = ENOMEM;
		return NULL;
	}

	/* for now, assume we should check the crc */
	state->dont_check_crc = 0;
#endif
	/* return stream */
	return state;
}

FILE_T
file_open(const char *path)
{
	int fd;
	FILE_T ft;
#ifdef HAVE_LIBZ
	const char *suffixp;
#endif

	/* open file and do correct filename conversions.

	   XXX - do we need O_LARGEFILE?  On UN*X, if we need to do
	   something special to get large file support, the configure
	   script should have set us up with the appropriate #defines,
	   so we should be getting a large-file-enabled file descriptor
	   here.  Pre-Large File Summit UN*Xes, and possibly even some
	   post-LFS UN*Xes, might require O_LARGEFILE here, though.
	   If so, we should probably handle that in ws_open(). */
	if ((fd = ws_open(path, O_RDONLY|O_BINARY, 0000)) == -1)
		return NULL;

	/* open file handle */
	ft = file_fdopen(fd);
	if (ft == NULL) {
		ws_close(fd);
		return NULL;
	}

#ifdef HAVE_LIBZ
	/*
	 * If this file's name ends in ".caz", it's probably a compressed
	 * Windows Sniffer file.  The compression is gzip, but if we
	 * process the CRC as specified by RFC 1952, the computed CRC
	 * doesn't match the stored CRC.
	 *
	 * Compressed Windows Sniffer files don't all have the same CRC
	 * value; is it just random crap, or are they running the CRC on
	 * a different set of data than you're supposed to (e.g., not
	 * CRCing some of the data), or something such as that?
	 *
	 * For now, we just set a flag to ignore CRC errors.
	 */
	suffixp = strrchr(path, '.');
	if (suffixp != NULL) {
		if (g_ascii_strcasecmp(suffixp, ".caz") == 0)
			ft->dont_check_crc = 1;
	}
#endif

	return ft;
}

void 
file_set_random_access(FILE_T stream, gboolean random _U_, GPtrArray *seek)
{
	stream->fast_seek = seek;
}

gint64
file_seek(FILE_T file, gint64 offset, int whence, int *err)
{
	struct fast_seek_point *here;
	unsigned n;

	/* can only seek from start or relative to current position */
	if (whence != SEEK_SET && whence != SEEK_CUR) {
		g_assert_not_reached();
/*
		*err = EINVAL;
		return -1;
 */
	}

	/* normalize offset to a SEEK_CUR specification */
	if (whence == SEEK_SET)
		offset -= file->pos;
	else if (file->seek)
		offset += file->skip;
	file->seek = 0;

	if (offset < 0 && file->next) {
		ptrdiff_t had = file->next - file->out;
		if (-offset <= had) {
			file->have -= offset;
			file->next += offset;
			file->pos += offset;
			return file->pos;
		}
	}

	/* XXX, profile */
	if ((here = fast_seek_find(file, file->pos + offset)) && (offset < 0 || offset > SPAN || here->compression == UNCOMPRESSED)) {
		gint64 off, off2;

#ifdef HAVE_LIBZ
		if (here->compression == ZLIB) {
#ifdef HAVE_INFLATEPRIME
			off = here->in - (here->data.zlib.bits ? 1 : 0);
#else
			off = here->in;
#endif
			off2 = here->out;
		} else if (here->compression == GZIP_AFTER_HEADER) {
			off = here->in;
			off2 = here->out;
		} else
#endif
		{
			off2 = (file->pos + offset);
			off = here->in + (off2 - here->out);
		}

		if (ws_lseek64(file->fd, off, SEEK_SET) == -1) {
			*err = errno;
			return -1;
		}
		fast_seek_reset(file);

		file->raw_pos = off;
		file->have = 0;
		file->eof = 0;
		file->seek = 0;
		file->err = 0;
		file->err_info = NULL;
		file->avail_in = 0;

#ifdef HAVE_LIBZ
		if (here->compression == ZLIB) {
			z_stream *strm = &file->strm;

			inflateReset(strm);
			strm->adler = here->data.zlib.adler;
			strm->total_out = here->data.zlib.total_out;
#ifdef HAVE_INFLATEPRIME
			if (here->data.zlib.bits) {
				FILE_T state = file;
				int ret = GZ_GETC();

				if (ret == -1) {
					if (state->err == 0) {
						/* EOF */
						*err = WTAP_ERR_SHORT_READ;
					} else
						*err = state->err;
					return -1;
				}
				(void)inflatePrime(strm, here->data.zlib.bits, ret >> (8 - here->data.zlib.bits));
			}
#endif
			(void)inflateSetDictionary(strm, here->data.zlib.window, ZLIB_WINSIZE);
			file->compression = ZLIB;
		} else if (here->compression == GZIP_AFTER_HEADER) {
			z_stream *strm = &file->strm;

			inflateReset(strm);
			strm->adler = crc32(0L, Z_NULL, 0);
			file->compression = ZLIB;
		} else
#endif
			file->compression = here->compression;

		offset = (file->pos + offset) - off2;
		file->pos = off2;
		/* g_print("OK! %ld\n", offset); */

		if (offset) {
			file->seek = 1;
			file->skip = offset;
		}
		return file->pos + offset;
	}

	/* if within raw area while reading, just go there */
	if (file->compression == UNCOMPRESSED && file->pos + offset >= file->raw 
			&& (offset < 0 || offset >= file->have) /* seek only when we don't have that offset in buffer */)
	{
		if (ws_lseek64(file->fd, offset - file->have, SEEK_CUR) == -1) {
			*err = errno;
			return -1;
		}
		file->raw_pos += (offset - file->have);
		file->have = 0;
		file->eof = 0;
		file->seek = 0;
		file->err = 0;
		file->err_info = NULL;
		file->avail_in = 0;
		file->pos += offset;
		return file->pos;
	}

	/* calculate skip amount, rewinding if needed for back seek when reading */
	if (offset < 0) {
		offset += file->pos;
		if (offset < 0) {                    /* before start of file! */
			*err = EINVAL;
			return -1;
		}
		/* rewind, then skip to offset */

		/* back up and start over */
		if (ws_lseek64(file->fd, file->start, SEEK_SET) == -1) {
			*err = errno;
			return -1;
		}
		fast_seek_reset(file);
		file->raw_pos = file->start;
		gz_reset(file);
	}

	/* skip what's in output buffer (one less gzgetc() check) */
	n = (gint64)file->have > offset ? (unsigned)offset : file->have;
	file->have -= n;
	file->next += n;
	file->pos += n;
	offset -= n;

	/* request skip (if not zero) */
	if (offset) {
		file->seek = 1;
		file->skip = offset;
	}
	return file->pos + offset;
}

/*
 * Skip forward the specified number of bytes in the file.
 * Currently implemented as a wrapper around file_seek(),
 * but if, for example, we ever add support for reading
 * sequentially from a pipe, this could instead just skip
 * forward by reading the bytes in question.
 */
gint64
file_skip(FILE_T file, gint64 delta, int *err)
{
	return file_seek(file, delta, SEEK_CUR, err);
}

gint64
file_tell(FILE_T stream)
{
	/* return position */
	return stream->pos + (stream->seek ? stream->skip : 0);
}

gint64
file_tell_raw(FILE_T stream)
{
	return stream->raw_pos;
}

int
file_fstat(FILE_T stream, ws_statb64 *statb, int *err)
{
	if (ws_fstat64(stream->fd, statb) == -1) {
		if (err != NULL)
			*err = errno;
		return -1;
	}
	return 0;
}

gboolean
file_iscompressed(FILE_T stream)
{
	return stream->is_compressed;
}

int 
file_read(void *buf, unsigned int len, FILE_T file)
{
	unsigned got, n;

	/* if len is zero, avoid unnecessary operations */
	if (len == 0)
		return 0;

	/* process a skip request */
	if (file->seek) {
		file->seek = 0;
		if (gz_skip(file, file->skip) == -1)
			return -1;
	}

	/* get len bytes to buf, or less than len if at the end */
	got = 0;
	do {
		if (file->have) {
			/* We have stuff in the output buffer; copy
			   what we have. */
			n = file->have > len ? len : file->have;
			memcpy(buf, file->next, n);
			file->next += n;
			file->have -= n;
		} else if (file->err) {
			/* We have nothing in the output buffer, and
			   we have an error that may not have been
			   reported yet; that means we can't generate
			   any more data into the output buffer, so
			   return an error indication. */
			return -1;
		} else if (file->eof && file->avail_in == 0) {
			/* We have nothing in the output buffer, and
			   we're at the end of the input; just return
			   with what we've gotten so far. */
			break;
		} else {
			/* We have nothing in the output buffer, and
			   we can generate more data; get more output,
			   looking for header if required, and
			   keep looping to process the new stuff
			   in the output buffer. */
			if (fill_out_buffer(file) == -1)
				return -1;
			continue;       /* no progress yet -- go back to memcpy() above */
		}
		/* update progress */
		len -= n;
		buf = (char *)buf + n;
		got += n;
		file->pos += n;
	} while (len);

	return (int)got;
}

int
file_getc(FILE_T file)
{
	unsigned char buf[1];
	int ret;

	/* check that we're reading and that there's no error */
	if (file->err)
		return -1;

	/* try output buffer (no need to check for skip request) */
	if (file->have) {
		file->have--;
		file->pos++;
		return *(file->next)++;
	}

	ret = file_read(buf, 1, file);
	return ret < 1 ? -1 : buf[0];
}

char *
file_gets(char *buf, int len, FILE_T file)
{
	unsigned left, n;
	char *str;
	unsigned char *eol;

	/* check parameters */
	if (buf == NULL || len < 1)
		return NULL;

	/* check that there's no error */
	if (file->err)
		return NULL;

	/* process a skip request */
	if (file->seek) {
		file->seek = 0;
		if (gz_skip(file, file->skip) == -1)
			return NULL;
	}

	/* copy output bytes up to new line or len - 1, whichever comes first --
	   append a terminating zero to the string (we don't check for a zero in
	   the contents, let the user worry about that) */
	str = buf;
	left = (unsigned)len - 1;
	if (left) do {
		/* assure that something is in the output buffer */
		if (file->have == 0) {
			/* We have nothing in the output buffer. */
			if (file->err) {
				/* We have an error that may not have
				   been reported yet; that means we
				   can't generate any more data into
				   the output buffer, so return an
				   error indication. */
				return NULL;
			}
			if (fill_out_buffer(file) == -1)
				return NULL;            /* error */
			if (file->have == 0)  {     /* end of file */
				if (buf == str)         /* got bupkus */
					return NULL;
				break;                  /* got something -- return it */
			}
		}

		/* look for end-of-line in current output buffer */
		n = file->have > left ? left : file->have;
		eol = (unsigned char *)memchr(file->next, '\n', n);
		if (eol != NULL)
			n = (unsigned)(eol - file->next) + 1;

		/* copy through end-of-line, or remainder if not found */
		memcpy(buf, file->next, n);
		file->have -= n;
		file->next += n;
		file->pos += n;
		left -= n;
		buf += n;
	} while (left && eol == NULL);

	/* found end-of-line or out of space -- terminate string and return it */
	buf[0] = 0;
	return str;
}

int 
file_eof(FILE_T file)
{
	/* return end-of-file state */
	return (file->eof && file->avail_in == 0 && file->have == 0);
}

/*
 * Routine to return a Wiretap error code (0 for no error, an errno
 * for a file error, or a WTAP_ERR_ code for other errors) for an
 * I/O stream.  Also returns an error string for some errors.
 */
int
file_error(FILE_T fh, gchar **err_info)
{
	if (fh->err != 0) {
		*err_info = (fh->err_info == NULL) ? NULL : g_strdup(fh->err_info);
		return fh->err;
	}
	return 0;
}

void
file_clearerr(FILE_T stream)
{
	/* clear error and end-of-file */
	stream->err = 0;
	stream->err_info = NULL;
	stream->eof = 0;
}

void
file_fdclose(FILE_T file)
{
	ws_close(file->fd);
	file->fd = -1;
}

gboolean
file_fdreopen(FILE_T file, const char *path)
{
	int fd;

	if ((fd = ws_open(path, O_RDONLY|O_BINARY, 0000)) == -1)
		return FALSE;
	file->fd = fd;
	return TRUE;
}

void
file_close(FILE_T file)
{
	int fd = file->fd;

	/* free memory and close file */
	if (file->size) {
#ifdef HAVE_LIBZ
		inflateEnd(&(file->strm));
#endif
		g_free(file->out);
		g_free(file->in);
	}
	g_free(file->fast_seek_cur);
	file->err = 0;
	file->err_info = NULL;
	g_free(file);
	/*
	 * If fd is -1, somebody's done a file_closefd() on us, so
	 * we don't need to close the FD itself, and shouldn't do
	 * so.
	 */
	if (fd != -1)
		ws_close(fd);
}

#ifdef HAVE_LIBZ
/* internal gzip file state data structure for writing */
struct wtap_writer {
    int fd;                 /* file descriptor */
    gint64 pos;             /* current position in uncompressed data */
    unsigned size;          /* buffer size, zero if not allocated yet */
    unsigned want;          /* requested buffer size, default is GZBUFSIZE */
    unsigned char *in;      /* input buffer */
    unsigned char *out;     /* output buffer (double-sized when reading) */
    unsigned char *next;    /* next output data to deliver or write */
    int level;              /* compression level */
    int strategy;           /* compression strategy */
    int err;                /* error code */
	/* zlib deflate stream */
    z_stream strm;          /* stream structure in-place (not a pointer) */
};

GZWFILE_T
gzwfile_open(const char *path)
{
    int fd;
    GZWFILE_T state;
    int save_errno;

    fd = ws_open(path, O_BINARY|O_WRONLY|O_CREAT|O_TRUNC, 0666);
    if (fd == -1)
        return NULL;
    state = gzwfile_fdopen(fd);
    if (state == NULL) {
        save_errno = errno;
        close(fd);
        errno = save_errno;
    }
    return state;
}

GZWFILE_T
gzwfile_fdopen(int fd)
{
    GZWFILE_T state;

    /* allocate wtap_writer structure to return */
    state = (GZWFILE_T)g_try_malloc(sizeof *state);
    if (state == NULL)
        return NULL;
    state->fd = fd;
    state->size = 0;            /* no buffers allocated yet */
    state->want = GZBUFSIZE;    /* requested buffer size */

    state->level = Z_DEFAULT_COMPRESSION;
    state->strategy = Z_DEFAULT_STRATEGY;

    /* initialize stream */
    state->err = Z_OK;              /* clear error */
    state->pos = 0;                 /* no uncompressed data yet */
    state->strm.avail_in = 0;       /* no input data yet */

    /* return stream */
    return state;
}

/* Initialize state for writing a gzip file.  Mark initialization by setting
   state->size to non-zero.  Return -1, and set state->err, on failure;
   return 0 on success. */
static int
gz_init(GZWFILE_T state)
{
    int ret;
    z_streamp strm = &(state->strm);

    /* allocate input and output buffers */
    state->in = (unsigned char *)g_try_malloc(state->want);
    state->out = (unsigned char *)g_try_malloc(state->want);
    if (state->in == NULL || state->out == NULL) {
        g_free(state->out);
        g_free(state->in);
        state->err = ENOMEM;
        return -1;
    }

    /* allocate deflate memory, set up for gzip compression */
    strm->zalloc = Z_NULL;
    strm->zfree = Z_NULL;
    strm->opaque = Z_NULL;
    ret = deflateInit2(strm, state->level, Z_DEFLATED,
                       15 + 16, 8, state->strategy);
    if (ret != Z_OK) {
        g_free(state->out);
        g_free(state->in);
        if (ret == Z_MEM_ERROR) {
        	/* This means "not enough memory". */
        	state->err = ENOMEM;
        } else {
        	/* This "shouldn't happen". */
        	state->err = WTAP_ERR_INTERNAL;
        }
        return -1;
    }

    /* mark state as initialized */
    state->size = state->want;

    /* initialize write buffer */
    strm->avail_out = state->size;
    strm->next_out = state->out;
    state->next = strm->next_out;
    return 0;
}

/* Compress whatever is at avail_in and next_in and write to the output file.
   Return -1, and set state->err, if there is an error writing to the output
   file; return 0 on success.
   flush is assumed to be a valid deflate() flush value.  If flush is Z_FINISH,
   then the deflate() state is reset to start a new gzip stream. */
static int
gz_comp(GZWFILE_T state, int flush)
{
    int ret, got;
    unsigned have;
    z_streamp strm = &(state->strm);

    /* allocate memory if this is the first time through */
    if (state->size == 0 && gz_init(state) == -1)
        return -1;

    /* run deflate() on provided input until it produces no more output */
    ret = Z_OK;
    do {
        /* write out current buffer contents if full, or if flushing, but if
           doing Z_FINISH then don't write until we get to Z_STREAM_END */
        if (strm->avail_out == 0 || (flush != Z_NO_FLUSH &&
            (flush != Z_FINISH || ret == Z_STREAM_END))) {
            have = (unsigned)(strm->next_out - state->next);
            if (have) {
		got = write(state->fd, state->next, have);
		if (got < 0) {
                    state->err = errno;
                    return -1;
                }
                if ((unsigned)got != have) {
                    state->err = WTAP_ERR_SHORT_WRITE;
                    return -1;
                }
            }
            if (strm->avail_out == 0) {
                strm->avail_out = state->size;
                strm->next_out = state->out;
            }
            state->next = strm->next_out;
        }

        /* compress */
        have = strm->avail_out;
        ret = deflate(strm, flush);
        if (ret == Z_STREAM_ERROR) {
            /* This "shouldn't happen". */
            state->err = WTAP_ERR_INTERNAL;
            return -1;
        }
        have -= strm->avail_out;
    } while (have);

    /* if that completed a deflate stream, allow another to start */
    if (flush == Z_FINISH)
        deflateReset(strm);

    /* all done, no errors */
    return 0;
}

/* Write out len bytes from buf.  Return 0, and set state->err, on
   failure or on an attempt to write 0 bytes (in which case state->err
   is Z_OK); return the number of bytes written on success. */
unsigned
gzwfile_write(GZWFILE_T state, const void *buf, unsigned len)
{
    unsigned put = len;
    unsigned n;
    z_streamp strm;

    strm = &(state->strm);

    /* check that there's no error */
    if (state->err != Z_OK)
        return 0;

    /* if len is zero, avoid unnecessary operations */
    if (len == 0)
        return 0;

    /* allocate memory if this is the first time through */
    if (state->size == 0 && gz_init(state) == -1)
        return 0;

    /* for small len, copy to input buffer, otherwise compress directly */
    if (len < state->size) {
        /* copy to input buffer, compress when full */
        do {
            if (strm->avail_in == 0)
                strm->next_in = state->in;
            n = state->size - strm->avail_in;
            if (n > len)
                n = len;
            memcpy(strm->next_in + strm->avail_in, buf, n);
            strm->avail_in += n;
            state->pos += n;
            buf = (char *)buf + n;
            len -= n;
            if (len && gz_comp(state, Z_NO_FLUSH) == -1)
                return 0;
        } while (len);
    }
    else {
        /* consume whatever's left in the input buffer */
        if (strm->avail_in && gz_comp(state, Z_NO_FLUSH) == -1)
            return 0;

        /* directly compress user buffer to file */
        strm->avail_in = len;
        strm->next_in = (voidp)buf;
        state->pos += len;
        if (gz_comp(state, Z_NO_FLUSH) == -1)
            return 0;
    }

    /* input was all buffered or compressed (put will fit in int) */
    return (int)put;
}

/* Flush out what we've written so far.  Returns -1, and sets state->err,
   on failure; returns 0 on success. */
int
gzwfile_flush(GZWFILE_T state)
{
    /* check that there's no error */
    if (state->err != Z_OK)
        return -1;

    /* compress remaining data with Z_SYNC_FLUSH */
    gz_comp(state, Z_SYNC_FLUSH);
    if (state->err != Z_OK)
        return -1;
    return 0;
}

/* Flush out all data written, and close the file.  Returns a Wiretap
   error on failure; returns 0 on success. */
int
gzwfile_close(GZWFILE_T state)
{
    int ret = 0;

    /* flush, free memory, and close file */
    if (gz_comp(state, Z_FINISH) == -1 && ret == 0)
        ret = state->err;
    (void)deflateEnd(&(state->strm));
    g_free(state->out);
    g_free(state->in);
    state->err = Z_OK;
    if (close(state->fd) == -1 && ret == 0)
        ret = errno;
    g_free(state);
    return ret;
}

int
gzwfile_geterr(GZWFILE_T state)
{
    return state->err;
}
#endif