1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2 version 1.2.8, April 28th, 2013
4 Copyright (C) 1995-2013 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://tools.ietf.org/html/rfc1950
28 (zlib format), rfc1951 (deflate format) and rfc1952 (gzip format).
36 #include "hammer2_zlib_zconf.h"
42 #define ZLIB_VERSION "1.2.8"
43 #define ZLIB_VERNUM 0x1280
44 #define ZLIB_VER_MAJOR 1
45 #define ZLIB_VER_MINOR 2
46 #define ZLIB_VER_REVISION 8
47 #define ZLIB_VER_SUBREVISION 0
50 The 'zlib' compression library provides in-memory compression and
51 decompression functions, including integrity checks of the uncompressed data.
52 This version of the library supports only one compression method (deflation)
53 but other algorithms will be added later and will have the same stream
56 Compression can be done in a single step if the buffers are large enough,
57 or can be done by repeated calls of the compression function. In the latter
58 case, the application must provide more input and/or consume the output
59 (providing more output space) before each call.
61 The compressed data format used by default by the in-memory functions is
62 the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
63 around a deflate stream, which is itself documented in RFC 1951.
65 The library also supports reading and writing files in gzip (.gz) format
66 with an interface similar to that of stdio using the functions that start
67 with "gz". The gzip format is different from the zlib format. gzip is a
68 gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
70 This library can optionally read and write gzip streams in memory as well.
72 The zlib format was designed to be compact and fast for use in memory
73 and on communications channels. The gzip format was designed for single-
74 file compression on file systems, has a larger header than zlib to maintain
75 directory information, and uses a different, slower check method than zlib.
77 The library does not install any signal handler. The decoder checks
78 the consistency of the compressed data, so the library should never crash
79 even in case of corrupted input.
82 struct internal_state;
84 typedef struct z_stream_s {
85 z_const Bytef *next_in; /* next input byte */
86 uInt avail_in; /* number of bytes available at next_in */
87 uLong total_in; /* total number of input bytes read so far */
89 Bytef *next_out; /* next output byte should be put there */
90 uInt avail_out; /* remaining free space at next_out */
91 uLong total_out; /* total number of bytes output so far */
93 z_const char *msg; /* last error message, NULL if no error */
94 struct internal_state FAR *state; /* not visible by applications */
96 int data_type; /* best guess about the data type: binary or text */
97 uLong adler; /* adler32 value of the uncompressed data */
98 uLong reserved; /* reserved for future use */
101 typedef z_stream FAR *z_streamp;
104 The application must update next_in and avail_in when avail_in has dropped
105 to zero. It must update next_out and avail_out when avail_out has dropped
106 to zero. The application must initialize zalloc, zfree and opaque before
107 calling the init function. All other fields are set by the compression
108 library and must not be updated by the application.
110 The opaque value provided by the application will be passed as the first
111 parameter for calls of zalloc and zfree. This can be useful for custom
112 memory management. The compression library attaches no meaning to the
115 zalloc must return Z_NULL if there is not enough memory for the object.
116 If zlib is used in a multi-threaded application, zalloc and zfree must be
119 On 16-bit systems, the functions zalloc and zfree must be able to allocate
120 exactly 65536 bytes, but will not be required to allocate more than this if
121 the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS, pointers
122 returned by zalloc for objects of exactly 65536 bytes *must* have their
123 offset normalized to zero. The default allocation function provided by this
124 library ensures this (see zutil.c). To reduce memory requirements and avoid
125 any allocation of 64K objects, at the expense of compression ratio, compile
126 the library with -DMAX_WBITS=14 (see zconf.h).
128 The fields total_in and total_out can be used for statistics or progress
129 reports. After compression, total_in holds the total size of the
130 uncompressed data and may be saved for use in the decompressor (particularly
131 if the decompressor wants to decompress everything in a single step).
137 #define Z_PARTIAL_FLUSH 1
138 #define Z_SYNC_FLUSH 2
139 #define Z_FULL_FLUSH 3
143 /* Allowed flush values; see deflate() and inflate() below for details */
146 #define Z_STREAM_END 1
147 #define Z_NEED_DICT 2
149 #define Z_STREAM_ERROR (-2)
150 #define Z_DATA_ERROR (-3)
151 #define Z_MEM_ERROR (-4)
152 #define Z_BUF_ERROR (-5)
153 #define Z_VERSION_ERROR (-6)
154 /* Return codes for the compression/decompression functions. Negative values
155 * are errors, positive values are used for special but normal events.
158 #define Z_NO_COMPRESSION 0
159 #define Z_BEST_SPEED 1
160 #define Z_BEST_COMPRESSION 9
161 #define Z_DEFAULT_COMPRESSION (-1)
162 /* compression levels */
165 #define Z_HUFFMAN_ONLY 2
168 #define Z_DEFAULT_STRATEGY 0
169 /* compression strategy; see deflateInit2() below for details */
173 #define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
175 /* Possible values of the data_type field (though see inflate()) */
178 /* The deflate compression method (the only one supported in this version) */
180 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
182 #define zlib_version zlibVersion()
183 /* for compatibility with versions < 1.0.2 */
186 /* basic functions */
188 //ZEXTERN const char * ZEXPORT zlibVersion OF((void));
189 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
190 If the first character differs, the library code actually used is not
191 compatible with the zlib.h header file used by the application. This check
192 is automatically made by deflateInit and inflateInit.
195 int deflateInit(z_streamp strm, int level);
198 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
200 Initializes the internal stream state for compression. The fields
201 zalloc, zfree and opaque must be initialized before by the caller. If
202 zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
203 allocation functions.
205 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
206 1 gives best speed, 9 gives best compression, 0 gives no compression at all
207 (the input data is simply copied a block at a time). Z_DEFAULT_COMPRESSION
208 requests a default compromise between speed and compression (currently
209 equivalent to level 6).
211 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
212 memory, Z_STREAM_ERROR if level is not a valid compression level, or
213 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
214 with the version assumed by the caller (ZLIB_VERSION). msg is set to null
215 if there is no error message. deflateInit does not perform any compression:
216 this will be done by deflate().
220 int deflate(z_streamp strm, int flush);
222 deflate compresses as much data as possible, and stops when the input
223 buffer becomes empty or the output buffer becomes full. It may introduce
224 some output latency (reading input without producing any output) except when
227 The detailed semantics are as follows. deflate performs one or both of the
230 - Compress more input starting at next_in and update next_in and avail_in
231 accordingly. If not all input can be processed (because there is not
232 enough room in the output buffer), next_in and avail_in are updated and
233 processing will resume at this point for the next call of deflate().
235 - Provide more output starting at next_out and update next_out and avail_out
236 accordingly. This action is forced if the parameter flush is non zero.
237 Forcing flush frequently degrades the compression ratio, so this parameter
238 should be set only when necessary (in interactive applications). Some
239 output may be provided even if flush is not set.
241 Before the call of deflate(), the application should ensure that at least
242 one of the actions is possible, by providing more input and/or consuming more
243 output, and updating avail_in or avail_out accordingly; avail_out should
244 never be zero before the call. The application can consume the compressed
245 output when it wants, for example when the output buffer is full (avail_out
246 == 0), or after each call of deflate(). If deflate returns Z_OK and with
247 zero avail_out, it must be called again after making room in the output
248 buffer because there might be more output pending.
250 Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
251 decide how much data to accumulate before producing output, in order to
252 maximize compression.
254 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
255 flushed to the output buffer and the output is aligned on a byte boundary, so
256 that the decompressor can get all input data available so far. (In
257 particular avail_in is zero after the call if enough output space has been
258 provided before the call.) Flushing may degrade compression for some
259 compression algorithms and so it should be used only when necessary. This
260 completes the current deflate block and follows it with an empty stored block
261 that is three bits plus filler bits to the next byte, followed by four bytes
264 If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
265 output buffer, but the output is not aligned to a byte boundary. All of the
266 input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
267 This completes the current deflate block and follows it with an empty fixed
268 codes block that is 10 bits long. This assures that enough bytes are output
269 in order for the decompressor to finish the block before the empty fixed code
272 If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
273 for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
274 seven bits of the current block are held to be written as the next byte after
275 the next deflate block is completed. In this case, the decompressor may not
276 be provided enough bits at this point in order to complete decompression of
277 the data provided so far to the compressor. It may need to wait for the next
278 block to be emitted. This is for advanced applications that need to control
279 the emission of deflate blocks.
281 If flush is set to Z_FULL_FLUSH, all output is flushed as with
282 Z_SYNC_FLUSH, and the compression state is reset so that decompression can
283 restart from this point if previous compressed data has been damaged or if
284 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
287 If deflate returns with avail_out == 0, this function must be called again
288 with the same value of the flush parameter and more output space (updated
289 avail_out), until the flush is complete (deflate returns with non-zero
290 avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
291 avail_out is greater than six to avoid repeated flush markers due to
292 avail_out == 0 on return.
294 If the parameter flush is set to Z_FINISH, pending input is processed,
295 pending output is flushed and deflate returns with Z_STREAM_END if there was
296 enough output space; if deflate returns with Z_OK, this function must be
297 called again with Z_FINISH and more output space (updated avail_out) but no
298 more input data, until it returns with Z_STREAM_END or an error. After
299 deflate has returned Z_STREAM_END, the only possible operations on the stream
300 are deflateReset or deflateEnd.
302 Z_FINISH can be used immediately after deflateInit if all the compression
303 is to be done in a single step. In this case, avail_out must be at least the
304 value returned by deflateBound (see below). Then deflate is guaranteed to
305 return Z_STREAM_END. If not enough output space is provided, deflate will
306 not return Z_STREAM_END, and it must be called again as described above.
308 deflate() sets strm->adler to the adler32 checksum of all input read
309 so far (that is, total_in bytes).
311 deflate() may update strm->data_type if it can make a good guess about
312 the input data type (Z_BINARY or Z_TEXT). In doubt, the data is considered
313 binary. This field is only for information purposes and does not affect the
314 compression algorithm in any manner.
316 deflate() returns Z_OK if some progress has been made (more input
317 processed or more output produced), Z_STREAM_END if all input has been
318 consumed and all output has been produced (only when flush is set to
319 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
320 if next_in or next_out was Z_NULL), Z_BUF_ERROR if no progress is possible
321 (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
322 fatal, and deflate() can be called again with more input and more output
323 space to continue compressing.
327 int deflateEnd(z_streamp strm);
329 All dynamically allocated data structures for this stream are freed.
330 This function discards any unprocessed input and does not flush any pending
333 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
334 stream state was inconsistent, Z_DATA_ERROR if the stream was freed
335 prematurely (some input or output was discarded). In the error case, msg
336 may be set but then points to a static string (which must not be
340 int inflateInit(z_streamp strm);
343 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
345 Initializes the internal stream state for decompression. The fields
346 next_in, avail_in, zalloc, zfree and opaque must be initialized before by
347 the caller. If next_in is not Z_NULL and avail_in is large enough (the
348 exact value depends on the compression method), inflateInit determines the
349 compression method from the zlib header and allocates all data structures
350 accordingly; otherwise the allocation will be deferred to the first call of
351 inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to
352 use default allocation functions.
354 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
355 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
356 version assumed by the caller, or Z_STREAM_ERROR if the parameters are
357 invalid, such as a null pointer to the structure. msg is set to null if
358 there is no error message. inflateInit does not perform any decompression
359 apart from possibly reading the zlib header if present: actual decompression
360 will be done by inflate(). (So next_in and avail_in may be modified, but
361 next_out and avail_out are unused and unchanged.) The current implementation
362 of inflateInit() does not process any header information -- that is deferred
363 until inflate() is called.
367 int inflate(z_streamp strm, int flush);
369 inflate decompresses as much data as possible, and stops when the input
370 buffer becomes empty or the output buffer becomes full. It may introduce
371 some output latency (reading input without producing any output) except when
374 The detailed semantics are as follows. inflate performs one or both of the
377 - Decompress more input starting at next_in and update next_in and avail_in
378 accordingly. If not all input can be processed (because there is not
379 enough room in the output buffer), next_in is updated and processing will
380 resume at this point for the next call of inflate().
382 - Provide more output starting at next_out and update next_out and avail_out
383 accordingly. inflate() provides as much output as possible, until there is
384 no more input data or no more space in the output buffer (see below about
385 the flush parameter).
387 Before the call of inflate(), the application should ensure that at least
388 one of the actions is possible, by providing more input and/or consuming more
389 output, and updating the next_* and avail_* values accordingly. The
390 application can consume the uncompressed output when it wants, for example
391 when the output buffer is full (avail_out == 0), or after each call of
392 inflate(). If inflate returns Z_OK and with zero avail_out, it must be
393 called again after making room in the output buffer because there might be
396 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
397 Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much
398 output as possible to the output buffer. Z_BLOCK requests that inflate()
399 stop if and when it gets to the next deflate block boundary. When decoding
400 the zlib or gzip format, this will cause inflate() to return immediately
401 after the header and before the first block. When doing a raw inflate,
402 inflate() will go ahead and process the first block, and will return when it
403 gets to the end of that block, or when it runs out of data.
405 The Z_BLOCK option assists in appending to or combining deflate streams.
406 Also to assist in this, on return inflate() will set strm->data_type to the
407 number of unused bits in the last byte taken from strm->next_in, plus 64 if
408 inflate() is currently decoding the last block in the deflate stream, plus
409 128 if inflate() returned immediately after decoding an end-of-block code or
410 decoding the complete header up to just before the first byte of the deflate
411 stream. The end-of-block will not be indicated until all of the uncompressed
412 data from that block has been written to strm->next_out. The number of
413 unused bits may in general be greater than seven, except when bit 7 of
414 data_type is set, in which case the number of unused bits will be less than
415 eight. data_type is set as noted here every time inflate() returns for all
416 flush options, and so can be used to determine the amount of currently
417 consumed input in bits.
419 The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
420 end of each deflate block header is reached, before any actual data in that
421 block is decoded. This allows the caller to determine the length of the
422 deflate block header for later use in random access within a deflate block.
423 256 is added to the value of strm->data_type when inflate() returns
424 immediately after reaching the end of the deflate block header.
426 inflate() should normally be called until it returns Z_STREAM_END or an
427 error. However if all decompression is to be performed in a single step (a
428 single call of inflate), the parameter flush should be set to Z_FINISH. In
429 this case all pending input is processed and all pending output is flushed;
430 avail_out must be large enough to hold all of the uncompressed data for the
431 operation to complete. (The size of the uncompressed data may have been
432 saved by the compressor for this purpose.) The use of Z_FINISH is not
433 required to perform an inflation in one step. However it may be used to
434 inform inflate that a faster approach can be used for the single inflate()
435 call. Z_FINISH also informs inflate to not maintain a sliding window if the
436 stream completes, which reduces inflate's memory footprint. If the stream
437 does not complete, either because not all of the stream is provided or not
438 enough output space is provided, then a sliding window will be allocated and
439 inflate() can be called again to continue the operation as if Z_NO_FLUSH had
442 In this implementation, inflate() always flushes as much output as
443 possible to the output buffer, and always uses the faster approach on the
444 first call. So the effects of the flush parameter in this implementation are
445 on the return value of inflate() as noted below, when inflate() returns early
446 when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
447 memory for a sliding window when Z_FINISH is used.
449 If a preset dictionary is needed after this call (see inflateSetDictionary
450 below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
451 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
452 strm->adler to the Adler-32 checksum of all output produced so far (that is,
453 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
454 below. At the end of the stream, inflate() checks that its computed adler32
455 checksum is equal to that saved by the compressor and returns Z_STREAM_END
456 only if the checksum is correct.
458 inflate() can decompress and check either zlib-wrapped or gzip-wrapped
459 deflate data. The header type is detected automatically, if requested when
460 initializing with inflateInit2(). Any information contained in the gzip
461 header is not retained, so applications that need that information should
462 instead use raw inflate, see inflateInit2() below, or inflateBack() and
463 perform their own processing of the gzip header and trailer. When processing
464 gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
465 producted so far. The CRC-32 is checked against the gzip trailer.
467 inflate() returns Z_OK if some progress has been made (more input processed
468 or more output produced), Z_STREAM_END if the end of the compressed data has
469 been reached and all uncompressed output has been produced, Z_NEED_DICT if a
470 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
471 corrupted (input stream not conforming to the zlib format or incorrect check
472 value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
473 next_in or next_out was Z_NULL), Z_MEM_ERROR if there was not enough memory,
474 Z_BUF_ERROR if no progress is possible or if there was not enough room in the
475 output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
476 inflate() can be called again with more input and more output space to
477 continue decompressing. If Z_DATA_ERROR is returned, the application may
478 then call inflateSync() to look for a good compression block if a partial
479 recovery of the data is desired.
483 int inflateEnd(z_streamp strm);
485 All dynamically allocated data structures for this stream are freed.
486 This function discards any unprocessed input and does not flush any pending
489 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
490 was inconsistent. In the error case, msg may be set but then points to a
491 static string (which must not be deallocated).
494 /* checksum functions */
497 These functions are not related to compression but are exported
498 anyway because they might be useful in applications using the compression
502 uLong adler32(uLong adler, const Bytef *buf, uInt len);
504 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
505 return the updated checksum. If buf is Z_NULL, this function returns the
506 required initial value for the checksum.
508 An Adler-32 checksum is almost as reliable as a crc32_zlib but can be computed
513 uLong adler = adler32(0L, Z_NULL, 0);
515 while (read_buffer(buffer, length) != EOF) {
516 adler = adler32(adler, buffer, length);
518 if (adler != original_adler) error();
521 /* various hacks, don't look :) */
523 /* deflateInit and inflateInit are macros to allow checking the zlib version
524 * and the compiler's view of z_stream:
526 int deflateInit_(z_streamp strm, int level,
527 const char *version, int stream_size);
528 int inflateInit_(z_streamp strm,
529 const char *version, int stream_size);
531 #define deflateInit(strm, level) \
532 deflateInit_((strm), (level), ZLIB_VERSION, (int)sizeof(z_stream))
533 #define inflateInit(strm) \
534 inflateInit_((strm), ZLIB_VERSION, (int)sizeof(z_stream))
535 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
536 deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
537 (strategy), ZLIB_VERSION, (int)sizeof(z_stream))
538 #define inflateInit2(strm, windowBits) \
539 inflateInit2_((strm), (windowBits), ZLIB_VERSION, \
540 (int)sizeof(z_stream))
542 /* hack for buggy compilers */
543 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
544 struct internal_state {int dummy;};