1
/* zlib.h -- interface of the 'zlib' general purpose compression library
2
version 1.2.5, April 19th, 2010
4
Copyright (C) 1995-2010 Jean-loup Gailly and Mark Adler
6
This software is provided 'as-is', without any express or implied
7
warranty. In no event will the authors be held liable for any damages
8
arising from the use of this software.
10
Permission is granted to anyone to use this software for any purpose,
11
including commercial applications, and to alter it and redistribute it
12
freely, subject to the following restrictions:
14
1. The origin of this software must not be misrepresented; you must not
15
claim that you wrote the original software. If you use this software
16
in a product, an acknowledgment in the product documentation would be
17
appreciated but is not required.
18
2. Altered source versions must be plainly marked as such, and must not be
19
misrepresented as being the original software.
20
3. This notice may not be removed or altered from any source distribution.
22
Jean-loup Gailly Mark Adler
23
jloup@gzip.org madler@alumni.caltech.edu
26
The data format used by the zlib library is described by RFCs (Request for
27
Comments) 1950 to 1952 in the files http://www.ietf.org/rfc/rfc1950.txt
28
(zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
40
#define ZLIB_VERSION "1.2.5"
41
#define ZLIB_VERNUM 0x1250
42
#define ZLIB_VER_MAJOR 1
43
#define ZLIB_VER_MINOR 2
44
#define ZLIB_VER_REVISION 5
45
#define ZLIB_VER_SUBREVISION 0
48
The 'zlib' compression library provides in-memory compression and
49
decompression functions, including integrity checks of the uncompressed data.
50
This version of the library supports only one compression method (deflation)
51
but other algorithms will be added later and will have the same stream
54
Compression can be done in a single step if the buffers are large enough,
55
or can be done by repeated calls of the compression function. In the latter
56
case, the application must provide more input and/or consume the output
57
(providing more output space) before each call.
59
The compressed data format used by default by the in-memory functions is
60
the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
61
around a deflate stream, which is itself documented in RFC 1951.
63
The library also supports reading and writing files in gzip (.gz) format
64
with an interface similar to that of stdio using the functions that start
65
with "gz". The gzip format is different from the zlib format. gzip is a
66
gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
68
This library can optionally read and write gzip streams in memory as well.
70
The zlib format was designed to be compact and fast for use in memory
71
and on communications channels. The gzip format was designed for single-
72
file compression on file systems, has a larger header than zlib to maintain
73
directory information, and uses a different, slower check method than zlib.
75
The library does not install any signal handler. The decoder checks
76
the consistency of the compressed data, so the library should never crash
77
even in case of corrupted input.
80
typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
81
typedef void (*free_func) OF((voidpf opaque, voidpf address));
83
struct internal_state;
85
typedef struct z_stream_s {
86
Bytef *next_in; /* next input byte */
87
uInt avail_in; /* number of bytes available at next_in */
88
uLong total_in; /* total nb of input bytes read so far */
90
Bytef *next_out; /* next output byte should be put there */
91
uInt avail_out; /* remaining free space at next_out */
92
uLong total_out; /* total nb of bytes output so far */
94
char *msg; /* last error message, NULL if no error */
95
struct internal_state FAR *state; /* not visible by applications */
97
alloc_func zalloc; /* used to allocate the internal state */
98
free_func zfree; /* used to free the internal state */
99
voidpf opaque; /* private data object passed to zalloc and zfree */
101
int data_type; /* best guess about the data type: binary or text */
102
uLong adler; /* adler32 value of the uncompressed data */
103
uLong reserved; /* reserved for future use */
106
typedef z_stream FAR *z_streamp;
109
gzip header information passed to and from zlib routines. See RFC 1952
110
for more details on the meanings of these fields.
112
typedef struct gz_header_s {
113
int text; /* true if compressed data believed to be text */
114
uLong time; /* modification time */
115
int xflags; /* extra flags (not used when writing a gzip file) */
116
int os; /* operating system */
117
Bytef *extra; /* pointer to extra field or Z_NULL if none */
118
uInt extra_len; /* extra field length (valid if extra != Z_NULL) */
119
uInt extra_max; /* space at extra (only when reading header) */
120
Bytef *name; /* pointer to zero-terminated file name or Z_NULL */
121
uInt name_max; /* space at name (only when reading header) */
122
Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */
123
uInt comm_max; /* space at comment (only when reading header) */
124
int hcrc; /* true if there was or will be a header crc */
125
int done; /* true when done reading gzip header (not used
126
when writing a gzip file) */
129
typedef gz_header FAR *gz_headerp;
132
The application must update next_in and avail_in when avail_in has dropped
133
to zero. It must update next_out and avail_out when avail_out has dropped
134
to zero. The application must initialize zalloc, zfree and opaque before
135
calling the init function. All other fields are set by the compression
136
library and must not be updated by the application.
138
The opaque value provided by the application will be passed as the first
139
parameter for calls of zalloc and zfree. This can be useful for custom
140
memory management. The compression library attaches no meaning to the
143
zalloc must return Z_NULL if there is not enough memory for the object.
144
If zlib is used in a multi-threaded application, zalloc and zfree must be
147
On 16-bit systems, the functions zalloc and zfree must be able to allocate
148
exactly 65536 bytes, but will not be required to allocate more than this if
149
the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS, pointers
150
returned by zalloc for objects of exactly 65536 bytes *must* have their
151
offset normalized to zero. The default allocation function provided by this
152
library ensures this (see zutil.c). To reduce memory requirements and avoid
153
any allocation of 64K objects, at the expense of compression ratio, compile
154
the library with -DMAX_WBITS=14 (see zconf.h).
156
The fields total_in and total_out can be used for statistics or progress
157
reports. After compression, total_in holds the total size of the
158
uncompressed data and may be saved for use in the decompressor (particularly
159
if the decompressor wants to decompress everything in a single step).
165
#define Z_PARTIAL_FLUSH 1
166
#define Z_SYNC_FLUSH 2
167
#define Z_FULL_FLUSH 3
171
/* Allowed flush values; see deflate() and inflate() below for details */
174
#define Z_STREAM_END 1
175
#define Z_NEED_DICT 2
177
#define Z_STREAM_ERROR (-2)
178
#define Z_DATA_ERROR (-3)
179
#define Z_MEM_ERROR (-4)
180
#define Z_BUF_ERROR (-5)
181
#define Z_VERSION_ERROR (-6)
182
/* Return codes for the compression/decompression functions. Negative values
183
* are errors, positive values are used for special but normal events.
186
#define Z_NO_COMPRESSION 0
187
#define Z_BEST_SPEED 1
188
#define Z_BEST_COMPRESSION 9
189
#define Z_DEFAULT_COMPRESSION (-1)
190
/* compression levels */
193
#define Z_HUFFMAN_ONLY 2
196
#define Z_DEFAULT_STRATEGY 0
197
/* compression strategy; see deflateInit2() below for details */
201
#define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
203
/* Possible values of the data_type field (though see inflate()) */
206
/* The deflate compression method (the only one supported in this version) */
208
#define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
210
#define zlib_version zlibVersion()
211
/* for compatibility with versions < 1.0.2 */
214
/* basic functions */
216
ZEXTERN const char * ZEXPORT zlibVersion OF((void));
217
/* The application can compare zlibVersion and ZLIB_VERSION for consistency.
218
If the first character differs, the library code actually used is not
219
compatible with the zlib.h header file used by the application. This check
220
is automatically made by deflateInit and inflateInit.
224
ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
226
Initializes the internal stream state for compression. The fields
227
zalloc, zfree and opaque must be initialized before by the caller. If
228
zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
229
allocation functions.
231
The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
232
1 gives best speed, 9 gives best compression, 0 gives no compression at all
233
(the input data is simply copied a block at a time). Z_DEFAULT_COMPRESSION
234
requests a default compromise between speed and compression (currently
235
equivalent to level 6).
237
deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
238
memory, Z_STREAM_ERROR if level is not a valid compression level, or
239
Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
240
with the version assumed by the caller (ZLIB_VERSION). msg is set to null
241
if there is no error message. deflateInit does not perform any compression:
242
this will be done by deflate().
246
ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
248
deflate compresses as much data as possible, and stops when the input
249
buffer becomes empty or the output buffer becomes full. It may introduce
250
some output latency (reading input without producing any output) except when
253
The detailed semantics are as follows. deflate performs one or both of the
256
- Compress more input starting at next_in and update next_in and avail_in
257
accordingly. If not all input can be processed (because there is not
258
enough room in the output buffer), next_in and avail_in are updated and
259
processing will resume at this point for the next call of deflate().
261
- Provide more output starting at next_out and update next_out and avail_out
262
accordingly. This action is forced if the parameter flush is non zero.
263
Forcing flush frequently degrades the compression ratio, so this parameter
264
should be set only when necessary (in interactive applications). Some
265
output may be provided even if flush is not set.
267
Before the call of deflate(), the application should ensure that at least
268
one of the actions is possible, by providing more input and/or consuming more
269
output, and updating avail_in or avail_out accordingly; avail_out should
270
never be zero before the call. The application can consume the compressed
271
output when it wants, for example when the output buffer is full (avail_out
272
== 0), or after each call of deflate(). If deflate returns Z_OK and with
273
zero avail_out, it must be called again after making room in the output
274
buffer because there might be more output pending.
276
Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
277
decide how much data to accumulate before producing output, in order to
278
maximize compression.
280
If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
281
flushed to the output buffer and the output is aligned on a byte boundary, so
282
that the decompressor can get all input data available so far. (In
283
particular avail_in is zero after the call if enough output space has been
284
provided before the call.) Flushing may degrade compression for some
285
compression algorithms and so it should be used only when necessary. This
286
completes the current deflate block and follows it with an empty stored block
287
that is three bits plus filler bits to the next byte, followed by four bytes
290
If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
291
output buffer, but the output is not aligned to a byte boundary. All of the
292
input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
293
This completes the current deflate block and follows it with an empty fixed
294
codes block that is 10 bits long. This assures that enough bytes are output
295
in order for the decompressor to finish the block before the empty fixed code
298
If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
299
for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
300
seven bits of the current block are held to be written as the next byte after
301
the next deflate block is completed. In this case, the decompressor may not
302
be provided enough bits at this point in order to complete decompression of
303
the data provided so far to the compressor. It may need to wait for the next
304
block to be emitted. This is for advanced applications that need to control
305
the emission of deflate blocks.
307
If flush is set to Z_FULL_FLUSH, all output is flushed as with
308
Z_SYNC_FLUSH, and the compression state is reset so that decompression can
309
restart from this point if previous compressed data has been damaged or if
310
random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
313
If deflate returns with avail_out == 0, this function must be called again
314
with the same value of the flush parameter and more output space (updated
315
avail_out), until the flush is complete (deflate returns with non-zero
316
avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
317
avail_out is greater than six to avoid repeated flush markers due to
318
avail_out == 0 on return.
320
If the parameter flush is set to Z_FINISH, pending input is processed,
321
pending output is flushed and deflate returns with Z_STREAM_END if there was
322
enough output space; if deflate returns with Z_OK, this function must be
323
called again with Z_FINISH and more output space (updated avail_out) but no
324
more input data, until it returns with Z_STREAM_END or an error. After
325
deflate has returned Z_STREAM_END, the only possible operations on the stream
326
are deflateReset or deflateEnd.
328
Z_FINISH can be used immediately after deflateInit if all the compression
329
is to be done in a single step. In this case, avail_out must be at least the
330
value returned by deflateBound (see below). If deflate does not return
331
Z_STREAM_END, then it must be called again as described above.
333
deflate() sets strm->adler to the adler32 checksum of all input read
334
so far (that is, total_in bytes).
336
deflate() may update strm->data_type if it can make a good guess about
337
the input data type (Z_BINARY or Z_TEXT). In doubt, the data is considered
338
binary. This field is only for information purposes and does not affect the
339
compression algorithm in any manner.
341
deflate() returns Z_OK if some progress has been made (more input
342
processed or more output produced), Z_STREAM_END if all input has been
343
consumed and all output has been produced (only when flush is set to
344
Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
345
if next_in or next_out was Z_NULL), Z_BUF_ERROR if no progress is possible
346
(for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
347
fatal, and deflate() can be called again with more input and more output
348
space to continue compressing.
352
ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
354
All dynamically allocated data structures for this stream are freed.
355
This function discards any unprocessed input and does not flush any pending
358
deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
359
stream state was inconsistent, Z_DATA_ERROR if the stream was freed
360
prematurely (some input or output was discarded). In the error case, msg
361
may be set but then points to a static string (which must not be
367
ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
369
Initializes the internal stream state for decompression. The fields
370
next_in, avail_in, zalloc, zfree and opaque must be initialized before by
371
the caller. If next_in is not Z_NULL and avail_in is large enough (the
372
exact value depends on the compression method), inflateInit determines the
373
compression method from the zlib header and allocates all data structures
374
accordingly; otherwise the allocation will be deferred to the first call of
375
inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to
376
use default allocation functions.
378
inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
379
memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
380
version assumed by the caller, or Z_STREAM_ERROR if the parameters are
381
invalid, such as a null pointer to the structure. msg is set to null if
382
there is no error message. inflateInit does not perform any decompression
383
apart from possibly reading the zlib header if present: actual decompression
384
will be done by inflate(). (So next_in and avail_in may be modified, but
385
next_out and avail_out are unused and unchanged.) The current implementation
386
of inflateInit() does not process any header information -- that is deferred
387
until inflate() is called.
391
ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
393
inflate decompresses as much data as possible, and stops when the input
394
buffer becomes empty or the output buffer becomes full. It may introduce
395
some output latency (reading input without producing any output) except when
398
The detailed semantics are as follows. inflate performs one or both of the
401
- Decompress more input starting at next_in and update next_in and avail_in
402
accordingly. If not all input can be processed (because there is not
403
enough room in the output buffer), next_in is updated and processing will
404
resume at this point for the next call of inflate().
406
- Provide more output starting at next_out and update next_out and avail_out
407
accordingly. inflate() provides as much output as possible, until there is
408
no more input data or no more space in the output buffer (see below about
409
the flush parameter).
411
Before the call of inflate(), the application should ensure that at least
412
one of the actions is possible, by providing more input and/or consuming more
413
output, and updating the next_* and avail_* values accordingly. The
414
application can consume the uncompressed output when it wants, for example
415
when the output buffer is full (avail_out == 0), or after each call of
416
inflate(). If inflate returns Z_OK and with zero avail_out, it must be
417
called again after making room in the output buffer because there might be
420
The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
421
Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much
422
output as possible to the output buffer. Z_BLOCK requests that inflate()
423
stop if and when it gets to the next deflate block boundary. When decoding
424
the zlib or gzip format, this will cause inflate() to return immediately
425
after the header and before the first block. When doing a raw inflate,
426
inflate() will go ahead and process the first block, and will return when it
427
gets to the end of that block, or when it runs out of data.
429
The Z_BLOCK option assists in appending to or combining deflate streams.
430
Also to assist in this, on return inflate() will set strm->data_type to the
431
number of unused bits in the last byte taken from strm->next_in, plus 64 if
432
inflate() is currently decoding the last block in the deflate stream, plus
433
128 if inflate() returned immediately after decoding an end-of-block code or
434
decoding the complete header up to just before the first byte of the deflate
435
stream. The end-of-block will not be indicated until all of the uncompressed
436
data from that block has been written to strm->next_out. The number of
437
unused bits may in general be greater than seven, except when bit 7 of
438
data_type is set, in which case the number of unused bits will be less than
439
eight. data_type is set as noted here every time inflate() returns for all
440
flush options, and so can be used to determine the amount of currently
441
consumed input in bits.
443
The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
444
end of each deflate block header is reached, before any actual data in that
445
block is decoded. This allows the caller to determine the length of the
446
deflate block header for later use in random access within a deflate block.
447
256 is added to the value of strm->data_type when inflate() returns
448
immediately after reaching the end of the deflate block header.
450
inflate() should normally be called until it returns Z_STREAM_END or an
451
error. However if all decompression is to be performed in a single step (a
452
single call of inflate), the parameter flush should be set to Z_FINISH. In
453
this case all pending input is processed and all pending output is flushed;
454
avail_out must be large enough to hold all the uncompressed data. (The size
455
of the uncompressed data may have been saved by the compressor for this
456
purpose.) The next operation on this stream must be inflateEnd to deallocate
457
the decompression state. The use of Z_FINISH is never required, but can be
458
used to inform inflate that a faster approach may be used for the single
461
In this implementation, inflate() always flushes as much output as
462
possible to the output buffer, and always uses the faster approach on the
463
first call. So the only effect of the flush parameter in this implementation
464
is on the return value of inflate(), as noted below, or when it returns early
465
because Z_BLOCK or Z_TREES is used.
467
If a preset dictionary is needed after this call (see inflateSetDictionary
468
below), inflate sets strm->adler to the adler32 checksum of the dictionary
469
chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
470
strm->adler to the adler32 checksum of all output produced so far (that is,
471
total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
472
below. At the end of the stream, inflate() checks that its computed adler32
473
checksum is equal to that saved by the compressor and returns Z_STREAM_END
474
only if the checksum is correct.
476
inflate() can decompress and check either zlib-wrapped or gzip-wrapped
477
deflate data. The header type is detected automatically, if requested when
478
initializing with inflateInit2(). Any information contained in the gzip
479
header is not retained, so applications that need that information should
480
instead use raw inflate, see inflateInit2() below, or inflateBack() and
481
perform their own processing of the gzip header and trailer.
483
inflate() returns Z_OK if some progress has been made (more input processed
484
or more output produced), Z_STREAM_END if the end of the compressed data has
485
been reached and all uncompressed output has been produced, Z_NEED_DICT if a
486
preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
487
corrupted (input stream not conforming to the zlib format or incorrect check
488
value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
489
next_in or next_out was Z_NULL), Z_MEM_ERROR if there was not enough memory,
490
Z_BUF_ERROR if no progress is possible or if there was not enough room in the
491
output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
492
inflate() can be called again with more input and more output space to
493
continue decompressing. If Z_DATA_ERROR is returned, the application may
494
then call inflateSync() to look for a good compression block if a partial
495
recovery of the data is desired.
499
ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
501
All dynamically allocated data structures for this stream are freed.
502
This function discards any unprocessed input and does not flush any pending
505
inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
506
was inconsistent. In the error case, msg may be set but then points to a
507
static string (which must not be deallocated).
511
/* Advanced functions */
514
The following functions are needed only in some special applications.
518
ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
525
This is another version of deflateInit with more compression options. The
526
fields next_in, zalloc, zfree and opaque must be initialized before by the
529
The method parameter is the compression method. It must be Z_DEFLATED in
530
this version of the library.
532
The windowBits parameter is the base two logarithm of the window size
533
(the size of the history buffer). It should be in the range 8..15 for this
534
version of the library. Larger values of this parameter result in better
535
compression at the expense of memory usage. The default value is 15 if
536
deflateInit is used instead.
538
windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
539
determines the window size. deflate() will then generate raw deflate data
540
with no zlib header or trailer, and will not compute an adler32 check value.
542
windowBits can also be greater than 15 for optional gzip encoding. Add
543
16 to windowBits to write a simple gzip header and trailer around the
544
compressed data instead of a zlib wrapper. The gzip header will have no
545
file name, no extra data, no comment, no modification time (set to zero), no
546
header crc, and the operating system will be set to 255 (unknown). If a
547
gzip stream is being written, strm->adler is a crc32 instead of an adler32.
549
The memLevel parameter specifies how much memory should be allocated
550
for the internal compression state. memLevel=1 uses minimum memory but is
551
slow and reduces compression ratio; memLevel=9 uses maximum memory for
552
optimal speed. The default value is 8. See zconf.h for total memory usage
553
as a function of windowBits and memLevel.
555
The strategy parameter is used to tune the compression algorithm. Use the
556
value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
557
filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
558
string match), or Z_RLE to limit match distances to one (run-length
559
encoding). Filtered data consists mostly of small values with a somewhat
560
random distribution. In this case, the compression algorithm is tuned to
561
compress them better. The effect of Z_FILTERED is to force more Huffman
562
coding and less string matching; it is somewhat intermediate between
563
Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as
564
fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data. The
565
strategy parameter only affects the compression ratio but not the
566
correctness of the compressed output even if it is not set appropriately.
567
Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
568
decoder for special applications.
570
deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
571
memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
572
method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
573
incompatible with the version assumed by the caller (ZLIB_VERSION). msg is
574
set to null if there is no error message. deflateInit2 does not perform any
575
compression: this will be done by deflate().
578
ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
579
const Bytef *dictionary,
582
Initializes the compression dictionary from the given byte sequence
583
without producing any compressed output. This function must be called
584
immediately after deflateInit, deflateInit2 or deflateReset, before any call
585
of deflate. The compressor and decompressor must use exactly the same
586
dictionary (see inflateSetDictionary).
588
The dictionary should consist of strings (byte sequences) that are likely
589
to be encountered later in the data to be compressed, with the most commonly
590
used strings preferably put towards the end of the dictionary. Using a
591
dictionary is most useful when the data to be compressed is short and can be
592
predicted with good accuracy; the data can then be compressed better than
593
with the default empty dictionary.
595
Depending on the size of the compression data structures selected by
596
deflateInit or deflateInit2, a part of the dictionary may in effect be
597
discarded, for example if the dictionary is larger than the window size
598
provided in deflateInit or deflateInit2. Thus the strings most likely to be
599
useful should be put at the end of the dictionary, not at the front. In
600
addition, the current implementation of deflate will use at most the window
601
size minus 262 bytes of the provided dictionary.
603
Upon return of this function, strm->adler is set to the adler32 value
604
of the dictionary; the decompressor may later use this value to determine
605
which dictionary has been used by the compressor. (The adler32 value
606
applies to the whole dictionary even if only a subset of the dictionary is
607
actually used by the compressor.) If a raw deflate was requested, then the
608
adler32 value is not computed and strm->adler is not set.
610
deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
611
parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
612
inconsistent (for example if deflate has already been called for this stream
613
or if the compression method is bsort). deflateSetDictionary does not
614
perform any compression: this will be done by deflate().
617
ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
620
Sets the destination stream as a complete copy of the source stream.
622
This function can be useful when several compression strategies will be
623
tried, for example when there are several ways of pre-processing the input
624
data with a filter. The streams that will be discarded should then be freed
625
by calling deflateEnd. Note that deflateCopy duplicates the internal
626
compression state which can be quite large, so this strategy is slow and can
627
consume lots of memory.
629
deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
630
enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
631
(such as zalloc being Z_NULL). msg is left unchanged in both source and
635
ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
637
This function is equivalent to deflateEnd followed by deflateInit,
638
but does not free and reallocate all the internal compression state. The
639
stream will keep the same compression level and any other attributes that
640
may have been set by deflateInit2.
642
deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
643
stream state was inconsistent (such as zalloc or state being Z_NULL).
646
ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
650
Dynamically update the compression level and compression strategy. The
651
interpretation of level and strategy is as in deflateInit2. This can be
652
used to switch between compression and straight copy of the input data, or
653
to switch to a different kind of input data requiring a different strategy.
654
If the compression level is changed, the input available so far is
655
compressed with the old level (and may be flushed); the new level will take
656
effect only at the next call of deflate().
658
Before the call of deflateParams, the stream state must be set as for
659
a call of deflate(), since the currently available input may have to be
660
compressed and flushed. In particular, strm->avail_out must be non-zero.
662
deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
663
stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR if
664
strm->avail_out was zero.
667
ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
673
Fine tune deflate's internal compression parameters. This should only be
674
used by someone who understands the algorithm used by zlib's deflate for
675
searching for the best matching string, and even then only by the most
676
fanatic optimizer trying to squeeze out the last compressed bit for their
677
specific input data. Read the deflate.c source code for the meaning of the
678
max_lazy, good_length, nice_length, and max_chain parameters.
680
deflateTune() can be called after deflateInit() or deflateInit2(), and
681
returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
684
ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
687
deflateBound() returns an upper bound on the compressed size after
688
deflation of sourceLen bytes. It must be called after deflateInit() or
689
deflateInit2(), and after deflateSetHeader(), if used. This would be used
690
to allocate an output buffer for deflation in a single pass, and so would be
691
called before deflate().
694
ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
698
deflatePrime() inserts bits in the deflate output stream. The intent
699
is that this function is used to start off the deflate output with the bits
700
leftover from a previous deflate stream when appending to it. As such, this
701
function can only be used for raw deflate, and must be used before the first
702
deflate() call after a deflateInit2() or deflateReset(). bits must be less
703
than or equal to 16, and that many of the least significant bits of value
704
will be inserted in the output.
706
deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
707
stream state was inconsistent.
710
ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
713
deflateSetHeader() provides gzip header information for when a gzip
714
stream is requested by deflateInit2(). deflateSetHeader() may be called
715
after deflateInit2() or deflateReset() and before the first call of
716
deflate(). The text, time, os, extra field, name, and comment information
717
in the provided gz_header structure are written to the gzip header (xflag is
718
ignored -- the extra flags are set according to the compression level). The
719
caller must assure that, if not Z_NULL, name and comment are terminated with
720
a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
721
available there. If hcrc is true, a gzip header crc is included. Note that
722
the current versions of the command-line version of gzip (up through version
723
1.3.x) do not support header crc's, and will report that it is a "multi-part
724
gzip file" and give up.
726
If deflateSetHeader is not used, the default gzip header has text false,
727
the time set to zero, and os set to 255, with no extra, name, or comment
728
fields. The gzip header is returned to the default state by deflateReset().
730
deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
731
stream state was inconsistent.
735
ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
738
This is another version of inflateInit with an extra parameter. The
739
fields next_in, avail_in, zalloc, zfree and opaque must be initialized
740
before by the caller.
742
The windowBits parameter is the base two logarithm of the maximum window
743
size (the size of the history buffer). It should be in the range 8..15 for
744
this version of the library. The default value is 15 if inflateInit is used
745
instead. windowBits must be greater than or equal to the windowBits value
746
provided to deflateInit2() while compressing, or it must be equal to 15 if
747
deflateInit2() was not used. If a compressed stream with a larger window
748
size is given as input, inflate() will return with the error code
749
Z_DATA_ERROR instead of trying to allocate a larger window.
751
windowBits can also be zero to request that inflate use the window size in
752
the zlib header of the compressed stream.
754
windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
755
determines the window size. inflate() will then process raw deflate data,
756
not looking for a zlib or gzip header, not generating a check value, and not
757
looking for any check values for comparison at the end of the stream. This
758
is for use with other formats that use the deflate compressed data format
759
such as zip. Those formats provide their own check values. If a custom
760
format is developed using the raw deflate format for compressed data, it is
761
recommended that a check value such as an adler32 or a crc32 be applied to
762
the uncompressed data as is done in the zlib, gzip, and zip formats. For
763
most applications, the zlib format should be used as is. Note that comments
764
above on the use in deflateInit2() applies to the magnitude of windowBits.
766
windowBits can also be greater than 15 for optional gzip decoding. Add
767
32 to windowBits to enable zlib and gzip decoding with automatic header
768
detection, or add 16 to decode only the gzip format (the zlib format will
769
return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is a
770
crc32 instead of an adler32.
772
inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
773
memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
774
version assumed by the caller, or Z_STREAM_ERROR if the parameters are
775
invalid, such as a null pointer to the structure. msg is set to null if
776
there is no error message. inflateInit2 does not perform any decompression
777
apart from possibly reading the zlib header if present: actual decompression
778
will be done by inflate(). (So next_in and avail_in may be modified, but
779
next_out and avail_out are unused and unchanged.) The current implementation
780
of inflateInit2() does not process any header information -- that is
781
deferred until inflate() is called.
784
ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
785
const Bytef *dictionary,
788
Initializes the decompression dictionary from the given uncompressed byte
789
sequence. This function must be called immediately after a call of inflate,
790
if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
791
can be determined from the adler32 value returned by that call of inflate.
792
The compressor and decompressor must use exactly the same dictionary (see
793
deflateSetDictionary). For raw inflate, this function can be called
794
immediately after inflateInit2() or inflateReset() and before any call of
795
inflate() to set the dictionary. The application must insure that the
796
dictionary that was used for compression is provided.
798
inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
799
parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
800
inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
801
expected one (incorrect adler32 value). inflateSetDictionary does not
802
perform any decompression: this will be done by subsequent calls of
806
ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
808
Skips invalid compressed data until a full flush point (see above the
809
description of deflate with Z_FULL_FLUSH) can be found, or until all
810
available input is skipped. No output is provided.
812
inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
813
if no more input was provided, Z_DATA_ERROR if no flush point has been
814
found, or Z_STREAM_ERROR if the stream structure was inconsistent. In the
815
success case, the application may save the current current value of total_in
816
which indicates where valid compressed data was found. In the error case,
817
the application may repeatedly call inflateSync, providing more input each
818
time, until success or end of the input data.
821
ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
824
Sets the destination stream as a complete copy of the source stream.
826
This function can be useful when randomly accessing a large stream. The
827
first pass through the stream can periodically record the inflate state,
828
allowing restarting inflate at those points when randomly accessing the
831
inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
832
enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
833
(such as zalloc being Z_NULL). msg is left unchanged in both source and
837
ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
839
This function is equivalent to inflateEnd followed by inflateInit,
840
but does not free and reallocate all the internal decompression state. The
841
stream will keep attributes that may have been set by inflateInit2.
843
inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
844
stream state was inconsistent (such as zalloc or state being Z_NULL).
847
ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
850
This function is the same as inflateReset, but it also permits changing
851
the wrap and window size requests. The windowBits parameter is interpreted
852
the same as it is for inflateInit2.
854
inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
855
stream state was inconsistent (such as zalloc or state being Z_NULL), or if
856
the windowBits parameter is invalid.
859
ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
863
This function inserts bits in the inflate input stream. The intent is
864
that this function is used to start inflating at a bit position in the
865
middle of a byte. The provided bits will be used before any bytes are used
866
from next_in. This function should only be used with raw inflate, and
867
should be used before the first inflate() call after inflateInit2() or
868
inflateReset(). bits must be less than or equal to 16, and that many of the
869
least significant bits of value will be inserted in the input.
871
If bits is negative, then the input stream bit buffer is emptied. Then
872
inflatePrime() can be called again to put bits in the buffer. This is used
873
to clear out bits leftover after feeding inflate a block description prior
874
to feeding inflate codes.
876
inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
877
stream state was inconsistent.
880
ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
882
This function returns two values, one in the lower 16 bits of the return
883
value, and the other in the remaining upper bits, obtained by shifting the
884
return value down 16 bits. If the upper value is -1 and the lower value is
885
zero, then inflate() is currently decoding information outside of a block.
886
If the upper value is -1 and the lower value is non-zero, then inflate is in
887
the middle of a stored block, with the lower value equaling the number of
888
bytes from the input remaining to copy. If the upper value is not -1, then
889
it is the number of bits back from the current bit position in the input of
890
the code (literal or length/distance pair) currently being processed. In
891
that case the lower value is the number of bytes already emitted for that
894
A code is being processed if inflate is waiting for more input to complete
895
decoding of the code, or if it has completed decoding but is waiting for
896
more output space to write the literal or match data.
898
inflateMark() is used to mark locations in the input data for random
899
access, which may be at bit positions, and to note those cases where the
900
output of a code may span boundaries of random access blocks. The current
901
location in the input stream can be determined from avail_in and data_type
902
as noted in the description for the Z_BLOCK flush parameter for inflate.
904
inflateMark returns the value noted above or -1 << 16 if the provided
905
source stream state was inconsistent.
908
ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
911
inflateGetHeader() requests that gzip header information be stored in the
912
provided gz_header structure. inflateGetHeader() may be called after
913
inflateInit2() or inflateReset(), and before the first call of inflate().
914
As inflate() processes the gzip stream, head->done is zero until the header
915
is completed, at which time head->done is set to one. If a zlib stream is
916
being decoded, then head->done is set to -1 to indicate that there will be
917
no gzip header information forthcoming. Note that Z_BLOCK or Z_TREES can be
918
used to force inflate() to return immediately after header processing is
919
complete and before any actual data is decompressed.
921
The text, time, xflags, and os fields are filled in with the gzip header
922
contents. hcrc is set to true if there is a header CRC. (The header CRC
923
was valid if done is set to one.) If extra is not Z_NULL, then extra_max
924
contains the maximum number of bytes to write to extra. Once done is true,
925
extra_len contains the actual extra field length, and extra contains the
926
extra field, or that field truncated if extra_max is less than extra_len.
927
If name is not Z_NULL, then up to name_max characters are written there,
928
terminated with a zero unless the length is greater than name_max. If
929
comment is not Z_NULL, then up to comm_max characters are written there,
930
terminated with a zero unless the length is greater than comm_max. When any
931
of extra, name, or comment are not Z_NULL and the respective field is not
932
present in the header, then that field is set to Z_NULL to signal its
933
absence. This allows the use of deflateSetHeader() with the returned
934
structure to duplicate the header. However if those fields are set to
935
allocated memory, then the application will need to save those pointers
936
elsewhere so that they can be eventually freed.
938
If inflateGetHeader is not used, then the header information is simply
939
discarded. The header is always checked for validity, including the header
940
CRC if present. inflateReset() will reset the process to discard the header
941
information. The application would need to call inflateGetHeader() again to
942
retrieve the header from the next gzip stream.
944
inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
945
stream state was inconsistent.
949
ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
950
unsigned char FAR *window));
952
Initialize the internal stream state for decompression using inflateBack()
953
calls. The fields zalloc, zfree and opaque in strm must be initialized
954
before the call. If zalloc and zfree are Z_NULL, then the default library-
955
derived memory allocation routines are used. windowBits is the base two
956
logarithm of the window size, in the range 8..15. window is a caller
957
supplied buffer of that size. Except for special applications where it is
958
assured that deflate was used with small window sizes, windowBits must be 15
959
and a 32K byte window must be supplied to be able to decompress general
962
See inflateBack() for the usage of these routines.
964
inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
965
the paramaters are invalid, Z_MEM_ERROR if the internal state could not be
966
allocated, or Z_VERSION_ERROR if the version of the library does not match
967
the version of the header file.
970
typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
971
typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
973
ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
974
in_func in, void FAR *in_desc,
975
out_func out, void FAR *out_desc));
977
inflateBack() does a raw inflate with a single call using a call-back
978
interface for input and output. This is more efficient than inflate() for
979
file i/o applications in that it avoids copying between the output and the
980
sliding window by simply making the window itself the output buffer. This
981
function trusts the application to not change the output buffer passed by
982
the output function, at least until inflateBack() returns.
984
inflateBackInit() must be called first to allocate the internal state
985
and to initialize the state with the user-provided window buffer.
986
inflateBack() may then be used multiple times to inflate a complete, raw
987
deflate stream with each call. inflateBackEnd() is then called to free the
990
A raw deflate stream is one with no zlib or gzip header or trailer.
991
This routine would normally be used in a utility that reads zip or gzip
992
files and writes out uncompressed files. The utility would decode the
993
header and process the trailer on its own, hence this routine expects only
994
the raw deflate stream to decompress. This is different from the normal
995
behavior of inflate(), which expects either a zlib or gzip header and
996
trailer around the deflate stream.
998
inflateBack() uses two subroutines supplied by the caller that are then
999
called by inflateBack() for input and output. inflateBack() calls those
1000
routines until it reads a complete deflate stream and writes out all of the
1001
uncompressed data, or until it encounters an error. The function's
1002
parameters and return types are defined above in the in_func and out_func
1003
typedefs. inflateBack() will call in(in_desc, &buf) which should return the
1004
number of bytes of provided input, and a pointer to that input in buf. If
1005
there is no input available, in() must return zero--buf is ignored in that
1006
case--and inflateBack() will return a buffer error. inflateBack() will call
1007
out(out_desc, buf, len) to write the uncompressed data buf[0..len-1]. out()
1008
should return zero on success, or non-zero on failure. If out() returns
1009
non-zero, inflateBack() will return with an error. Neither in() nor out()
1010
are permitted to change the contents of the window provided to
1011
inflateBackInit(), which is also the buffer that out() uses to write from.
1012
The length written by out() will be at most the window size. Any non-zero
1013
amount of input may be provided by in().
1015
For convenience, inflateBack() can be provided input on the first call by
1016
setting strm->next_in and strm->avail_in. If that input is exhausted, then
1017
in() will be called. Therefore strm->next_in must be initialized before
1018
calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
1019
immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
1020
must also be initialized, and then if strm->avail_in is not zero, input will
1021
initially be taken from strm->next_in[0 .. strm->avail_in - 1].
1023
The in_desc and out_desc parameters of inflateBack() is passed as the
1024
first parameter of in() and out() respectively when they are called. These
1025
descriptors can be optionally used to pass any information that the caller-
1026
supplied in() and out() functions need to do their job.
1028
On return, inflateBack() will set strm->next_in and strm->avail_in to
1029
pass back any unused input that was provided by the last in() call. The
1030
return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
1031
if in() or out() returned an error, Z_DATA_ERROR if there was a format error
1032
in the deflate stream (in which case strm->msg is set to indicate the nature
1033
of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
1034
In the case of Z_BUF_ERROR, an input or output error can be distinguished
1035
using strm->next_in which will be Z_NULL only if in() returned an error. If
1036
strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
1037
non-zero. (in() will always be called before out(), so strm->next_in is
1038
assured to be defined if out() returns non-zero.) Note that inflateBack()
1042
ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
1044
All memory allocated by inflateBackInit() is freed.
1046
inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
1047
state was inconsistent.
1050
ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
1051
/* Return flags indicating compile-time options.
1053
Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
1056
5.4: size of voidpf (pointer)
1057
7.6: size of z_off_t
1059
Compiler, assembler, and debug options:
1061
9: ASMV or ASMINF -- use ASM code
1062
10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
1065
One-time table building (smaller code, but not thread-safe if true):
1066
12: BUILDFIXED -- build static block decoding tables when needed
1067
13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
1070
Library content (indicates missing functionality):
1071
16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
1072
deflate code when not needed)
1073
17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
1074
and decode gzip streams (to avoid linking crc code)
1077
Operation variations (changes in library functionality):
1078
20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
1079
21: FASTEST -- deflate algorithm with only one, lowest compression level
1082
The sprintf variant used by gzprintf (zero is best):
1083
24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1084
25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1085
26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1092
/* utility functions */
1095
The following utility functions are implemented on top of the basic
1096
stream-oriented functions. To simplify the interface, some default options
1097
are assumed (compression level and memory usage, standard memory allocation
1098
functions). The source code of these utility functions can be modified if
1099
you need special options.
1102
ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
1103
const Bytef *source, uLong sourceLen));
1105
Compresses the source buffer into the destination buffer. sourceLen is
1106
the byte length of the source buffer. Upon entry, destLen is the total size
1107
of the destination buffer, which must be at least the value returned by
1108
compressBound(sourceLen). Upon exit, destLen is the actual size of the
1111
compress returns Z_OK if success, Z_MEM_ERROR if there was not
1112
enough memory, Z_BUF_ERROR if there was not enough room in the output
1116
ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
1117
const Bytef *source, uLong sourceLen,
1120
Compresses the source buffer into the destination buffer. The level
1121
parameter has the same meaning as in deflateInit. sourceLen is the byte
1122
length of the source buffer. Upon entry, destLen is the total size of the
1123
destination buffer, which must be at least the value returned by
1124
compressBound(sourceLen). Upon exit, destLen is the actual size of the
1127
compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1128
memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1129
Z_STREAM_ERROR if the level parameter is invalid.
1132
ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1134
compressBound() returns an upper bound on the compressed size after
1135
compress() or compress2() on sourceLen bytes. It would be used before a
1136
compress() or compress2() call to allocate the destination buffer.
1139
ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
1140
const Bytef *source, uLong sourceLen));
1142
Decompresses the source buffer into the destination buffer. sourceLen is
1143
the byte length of the source buffer. Upon entry, destLen is the total size
1144
of the destination buffer, which must be large enough to hold the entire
1145
uncompressed data. (The size of the uncompressed data must have been saved
1146
previously by the compressor and transmitted to the decompressor by some
1147
mechanism outside the scope of this compression library.) Upon exit, destLen
1148
is the actual size of the uncompressed buffer.
1150
uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1151
enough memory, Z_BUF_ERROR if there was not enough room in the output
1152
buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.
1156
/* gzip file access functions */
1159
This library supports reading and writing files in gzip (.gz) format with
1160
an interface similar to that of stdio, using the functions that start with
1161
"gz". The gzip format is different from the zlib format. gzip is a gzip
1162
wrapper, documented in RFC 1952, wrapped around a deflate stream.
1165
typedef voidp gzFile; /* opaque gzip file descriptor */
1168
ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1170
Opens a gzip (.gz) file for reading or writing. The mode parameter is as
1171
in fopen ("rb" or "wb") but can also include a compression level ("wb9") or
1172
a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only
1173
compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F'
1174
for fixed code compression as in "wb9F". (See the description of
1175
deflateInit2 for more information about the strategy parameter.) Also "a"
1176
can be used instead of "w" to request that the gzip stream that will be
1177
written be appended to the file. "+" will result in an error, since reading
1178
and writing to the same gzip file is not supported.
1180
gzopen can be used to read a file which is not in gzip format; in this
1181
case gzread will directly read from the file without decompression.
1183
gzopen returns NULL if the file could not be opened, if there was
1184
insufficient memory to allocate the gzFile state, or if an invalid mode was
1185
specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
1186
errno can be checked to determine if the reason gzopen failed was that the
1187
file could not be opened.
1190
ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1192
gzdopen associates a gzFile with the file descriptor fd. File descriptors
1193
are obtained from calls like open, dup, creat, pipe or fileno (if the file
1194
has been previously opened with fopen). The mode parameter is as in gzopen.
1196
The next call of gzclose on the returned gzFile will also close the file
1197
descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
1198
fd. If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
1199
mode);. The duplicated descriptor should be saved to avoid a leak, since
1200
gzdopen does not close fd if it fails.
1202
gzdopen returns NULL if there was insufficient memory to allocate the
1203
gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
1204
provided, or '+' was provided), or if fd is -1. The file descriptor is not
1205
used until the next gz* read, write, seek, or close operation, so gzdopen
1206
will not detect if fd is invalid (unless fd is -1).
1209
ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
1211
Set the internal buffer size used by this library's functions. The
1212
default buffer size is 8192 bytes. This function must be called after
1213
gzopen() or gzdopen(), and before any other calls that read or write the
1214
file. The buffer memory allocation is always deferred to the first read or
1215
write. Two buffers are allocated, either both of the specified size when
1216
writing, or one of the specified size and the other twice that size when
1217
reading. A larger buffer size of, for example, 64K or 128K bytes will
1218
noticeably increase the speed of decompression (reading).
1220
The new buffer size also affects the maximum length for gzprintf().
1222
gzbuffer() returns 0 on success, or -1 on failure, such as being called
1226
ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1228
Dynamically update the compression level or strategy. See the description
1229
of deflateInit2 for the meaning of these parameters.
1231
gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
1235
ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1237
Reads the given number of uncompressed bytes from the compressed file. If
1238
the input file was not in gzip format, gzread copies the given number of
1239
bytes into the buffer.
1241
After reaching the end of a gzip stream in the input, gzread will continue
1242
to read, looking for another gzip stream, or failing that, reading the rest
1243
of the input file directly without decompression. The entire input file
1244
will be read if gzread is called until it returns less than the requested
1247
gzread returns the number of uncompressed bytes actually read, less than
1248
len for end of file, or -1 for error.
1251
ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1252
voidpc buf, unsigned len));
1254
Writes the given number of uncompressed bytes into the compressed file.
1255
gzwrite returns the number of uncompressed bytes written or 0 in case of
1259
ZEXTERN int ZEXPORTVA gzprintf OF((gzFile file, const char *format, ...));
1261
Converts, formats, and writes the arguments to the compressed file under
1262
control of the format string, as in fprintf. gzprintf returns the number of
1263
uncompressed bytes actually written, or 0 in case of error. The number of
1264
uncompressed bytes written is limited to 8191, or one less than the buffer
1265
size given to gzbuffer(). The caller should assure that this limit is not
1266
exceeded. If it is exceeded, then gzprintf() will return an error (0) with
1267
nothing written. In this case, there may also be a buffer overflow with
1268
unpredictable consequences, which is possible only if zlib was compiled with
1269
the insecure functions sprintf() or vsprintf() because the secure snprintf()
1270
or vsnprintf() functions were not available. This can be determined using
1274
ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1276
Writes the given null-terminated string to the compressed file, excluding
1277
the terminating null character.
1279
gzputs returns the number of characters written, or -1 in case of error.
1282
ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1284
Reads bytes from the compressed file until len-1 characters are read, or a
1285
newline character is read and transferred to buf, or an end-of-file
1286
condition is encountered. If any characters are read or if len == 1, the
1287
string is terminated with a null character. If no characters are read due
1288
to an end-of-file or len < 1, then the buffer is left untouched.
1290
gzgets returns buf which is a null-terminated string, or it returns NULL
1291
for end-of-file or in case of error. If there was an error, the contents at
1292
buf are indeterminate.
1295
ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1297
Writes c, converted to an unsigned char, into the compressed file. gzputc
1298
returns the value that was written, or -1 in case of error.
1301
ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1303
Reads one byte from the compressed file. gzgetc returns this byte or -1
1304
in case of end of file or error.
1307
ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1309
Push one character back onto the stream to be read as the first character
1310
on the next read. At least one character of push-back is allowed.
1311
gzungetc() returns the character pushed, or -1 on failure. gzungetc() will
1312
fail if c is -1, and may fail if a character has been pushed but not read
1313
yet. If gzungetc is used immediately after gzopen or gzdopen, at least the
1314
output buffer size of pushed characters is allowed. (See gzbuffer above.)
1315
The pushed character will be discarded if the stream is repositioned with
1316
gzseek() or gzrewind().
1319
ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1321
Flushes all pending output into the compressed file. The parameter flush
1322
is as in the deflate() function. The return value is the zlib error number
1323
(see function gzerror below). gzflush is only permitted when writing.
1325
If the flush parameter is Z_FINISH, the remaining data is written and the
1326
gzip stream is completed in the output. If gzwrite() is called again, a new
1327
gzip stream will be started in the output. gzread() is able to read such
1328
concatented gzip streams.
1330
gzflush should be called only when strictly necessary because it will
1331
degrade compression if called too often.
1335
ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1336
z_off_t offset, int whence));
1338
Sets the starting position for the next gzread or gzwrite on the given
1339
compressed file. The offset represents a number of bytes in the
1340
uncompressed data stream. The whence parameter is defined as in lseek(2);
1341
the value SEEK_END is not supported.
1343
If the file is opened for reading, this function is emulated but can be
1344
extremely slow. If the file is opened for writing, only forward seeks are
1345
supported; gzseek then compresses a sequence of zeroes up to the new
1348
gzseek returns the resulting offset location as measured in bytes from
1349
the beginning of the uncompressed stream, or -1 in case of error, in
1350
particular if the file is opened for writing and the new starting position
1351
would be before the current position.
1354
ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
1356
Rewinds the given file. This function is supported only for reading.
1358
gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1362
ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
1364
Returns the starting position for the next gzread or gzwrite on the given
1365
compressed file. This position represents a number of bytes in the
1366
uncompressed data stream, and is zero when starting, even if appending or
1367
reading a gzip stream from the middle of a file using gzdopen().
1369
gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1373
ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));
1375
Returns the current offset in the file being read or written. This offset
1376
includes the count of bytes that precede the gzip stream, for example when
1377
appending or when using gzdopen() for reading. When reading, the offset
1378
does not include as yet unused buffered input. This information can be used
1379
for a progress indicator. On error, gzoffset() returns -1.
1382
ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1384
Returns true (1) if the end-of-file indicator has been set while reading,
1385
false (0) otherwise. Note that the end-of-file indicator is set only if the
1386
read tried to go past the end of the input, but came up short. Therefore,
1387
just like feof(), gzeof() may return false even if there is no more data to
1388
read, in the event that the last read request was for the exact number of
1389
bytes remaining in the input file. This will happen if the input file size
1390
is an exact multiple of the buffer size.
1392
If gzeof() returns true, then the read functions will return no more data,
1393
unless the end-of-file indicator is reset by gzclearerr() and the input file
1394
has grown since the previous end of file was detected.
1397
ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1399
Returns true (1) if file is being copied directly while reading, or false
1400
(0) if file is a gzip stream being decompressed. This state can change from
1401
false to true while reading the input file if the end of a gzip stream is
1402
reached, but is followed by data that is not another gzip stream.
1404
If the input file is empty, gzdirect() will return true, since the input
1405
does not contain a gzip stream.
1407
If gzdirect() is used immediately after gzopen() or gzdopen() it will
1408
cause buffers to be allocated to allow reading the file to determine if it
1409
is a gzip file. Therefore if gzbuffer() is used, it should be called before
1413
ZEXTERN int ZEXPORT gzclose OF((gzFile file));
1415
Flushes all pending output if necessary, closes the compressed file and
1416
deallocates the (de)compression state. Note that once file is closed, you
1417
cannot call gzerror with file, since its structures have been deallocated.
1418
gzclose must not be called more than once on the same file, just as free
1419
must not be called more than once on the same allocation.
1421
gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
1422
file operation error, or Z_OK on success.
1425
ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
1426
ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));
1428
Same as gzclose(), but gzclose_r() is only for use when reading, and
1429
gzclose_w() is only for use when writing or appending. The advantage to
1430
using these instead of gzclose() is that they avoid linking in zlib
1431
compression or decompression code that is not used when only reading or only
1432
writing respectively. If gzclose() is used, then both compression and
1433
decompression code will be included the application when linking to a static
1437
ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1439
Returns the error message for the last error which occurred on the given
1440
compressed file. errnum is set to zlib error number. If an error occurred
1441
in the file system and not in the compression library, errnum is set to
1442
Z_ERRNO and the application may consult errno to get the exact error code.
1444
The application must not modify the returned string. Future calls to
1445
this function may invalidate the previously returned string. If file is
1446
closed, then the string previously returned by gzerror will no longer be
1449
gzerror() should be used to distinguish errors from end-of-file for those
1450
functions above that do not distinguish those cases in their return values.
1453
ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1455
Clears the error and end-of-file flags for file. This is analogous to the
1456
clearerr() function in stdio. This is useful for continuing to read a gzip
1457
file that is being written concurrently.
1461
/* checksum functions */
1464
These functions are not related to compression but are exported
1465
anyway because they might be useful in applications using the compression
1469
ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1471
Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1472
return the updated checksum. If buf is Z_NULL, this function returns the
1473
required initial value for the checksum.
1475
An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
1480
uLong adler = adler32(0L, Z_NULL, 0);
1482
while (read_buffer(buffer, length) != EOF) {
1483
adler = adler32(adler, buffer, length);
1485
if (adler != original_adler) error();
1489
ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1492
Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
1493
and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1494
each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
1495
seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.
1498
ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
1500
Update a running CRC-32 with the bytes buf[0..len-1] and return the
1501
updated CRC-32. If buf is Z_NULL, this function returns the required
1502
initial value for the for the crc. Pre- and post-conditioning (one's
1503
complement) is performed within this function so it shouldn't be done by the
1508
uLong crc = crc32(0L, Z_NULL, 0);
1510
while (read_buffer(buffer, length) != EOF) {
1511
crc = crc32(crc, buffer, length);
1513
if (crc != original_crc) error();
1517
ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1519
Combine two CRC-32 check values into one. For two sequences of bytes,
1520
seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1521
calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
1522
check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1527
/* various hacks, don't look :) */
1529
/* deflateInit and inflateInit are macros to allow checking the zlib version
1530
* and the compiler's view of z_stream:
1532
ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1533
const char *version, int stream_size));
1534
ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1535
const char *version, int stream_size));
1536
ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
1537
int windowBits, int memLevel,
1538
int strategy, const char *version,
1540
ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1541
const char *version, int stream_size));
1542
ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1543
unsigned char FAR *window,
1544
const char *version,
1546
#define deflateInit(strm, level) \
1547
deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream))
1548
#define inflateInit(strm) \
1549
inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream))
1550
#define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1551
deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1552
(strategy), ZLIB_VERSION, sizeof(z_stream))
1553
#define inflateInit2(strm, windowBits) \
1554
inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
1555
#define inflateBackInit(strm, windowBits, window) \
1556
inflateBackInit_((strm), (windowBits), (window), \
1557
ZLIB_VERSION, sizeof(z_stream))
1559
/* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
1560
* change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
1561
* both are true, the application gets the *64 functions, and the regular
1562
* functions are changed to 64 bits) -- in case these are set on systems
1563
* without large file support, _LFS64_LARGEFILE must also be true
1565
#if defined(_LARGEFILE64_SOURCE) && _LFS64_LARGEFILE-0
1566
ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1567
ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
1568
ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
1569
ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
1570
ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
1571
ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
1574
#if !defined(ZLIB_INTERNAL) && _FILE_OFFSET_BITS-0 == 64 && _LFS64_LARGEFILE-0
1575
# define gzopen gzopen64
1576
# define gzseek gzseek64
1577
# define gztell gztell64
1578
# define gzoffset gzoffset64
1579
# define adler32_combine adler32_combine64
1580
# define crc32_combine crc32_combine64
1581
# ifdef _LARGEFILE64_SOURCE
1582
ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
1583
ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int));
1584
ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile));
1585
ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile));
1586
ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
1587
ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
1590
ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
1591
ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
1592
ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
1593
ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
1594
ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
1595
ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
1598
/* hack for buggy compilers */
1599
#if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
1600
struct internal_state {int dummy;};
1603
/* undocumented functions */
1604
ZEXTERN const char * ZEXPORT zError OF((int));
1605
ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp));
1606
ZEXTERN const uLongf * ZEXPORT get_crc_table OF((void));
1607
ZEXTERN int ZEXPORT inflateUndermine OF((z_streamp, int));
added
removed
nss/lib/zlib/zlib.h
