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/* zlib.h -- interface of the 'zlib' general purpose compression library
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version 1.0.4, Jul 24th, 1996.
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Copyright (C) 1995-1996 Jean-loup Gailly and Mark Adler
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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Jean-loup Gailly Mark Adler
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gzip@prep.ai.mit.edu madler@alumni.caltech.edu
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The data format used by the zlib library is described by RFCs (Request for
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Comments) 1950 to 1952 in the files ftp://ds.internic.net/rfc/rfc1950.txt
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(zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
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#define ZLIB_VERSION "1.0.4"
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The 'zlib' compression library provides in-memory compression and
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decompression functions, including integrity checks of the uncompressed
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data. This version of the library supports only one compression method
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(deflation) but other algorithms may be added later and will have the same
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For compression the application must provide the output buffer and
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may optionally provide the input buffer for optimization. For decompression,
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the application must provide the input buffer and may optionally provide
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the output buffer for optimization.
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Compression can be done in a single step if the buffers are large
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enough (for example if an input file is mmap'ed), or can be done by
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repeated calls of the compression function. In the latter case, the
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application must provide more input and/or consume the output
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(providing more output space) before each call.
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The library does not install any signal handler. It is recommended to
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add at least a handler for SIGSEGV when decompressing; the library checks
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the consistency of the input data whenever possible but may go nuts
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for some forms of corrupted input.
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typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
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typedef void (*free_func) OF((voidpf opaque, voidpf address));
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struct internal_state;
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typedef struct z_stream_s {
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Bytef *next_in; /* next input byte */
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uInt avail_in; /* number of bytes available at next_in */
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uLong total_in; /* total nb of input bytes read so far */
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Bytef *next_out; /* next output byte should be put there */
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uInt avail_out; /* remaining free space at next_out */
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uLong total_out; /* total nb of bytes output so far */
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char *msg; /* last error message, NULL if no error */
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struct internal_state FAR *state; /* not visible by applications */
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alloc_func zalloc; /* used to allocate the internal state */
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free_func zfree; /* used to free the internal state */
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voidpf opaque; /* private data object passed to zalloc and zfree */
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int data_type; /* best guess about the data type: ascii or binary */
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uLong adler; /* adler32 value of the uncompressed data */
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uLong reserved; /* reserved for future use */
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typedef z_stream FAR *z_streamp;
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The application must update next_in and avail_in when avail_in has
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dropped to zero. It must update next_out and avail_out when avail_out
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has dropped to zero. The application must initialize zalloc, zfree and
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opaque before calling the init function. All other fields are set by the
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compression library and must not be updated by the application.
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The opaque value provided by the application will be passed as the first
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parameter for calls of zalloc and zfree. This can be useful for custom
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memory management. The compression library attaches no meaning to the
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zalloc must return Z_NULL if there is not enough memory for the object.
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On 16-bit systems, the functions zalloc and zfree must be able to allocate
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exactly 65536 bytes, but will not be required to allocate more than this
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if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
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pointers returned by zalloc for objects of exactly 65536 bytes *must*
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have their offset normalized to zero. The default allocation function
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provided by this library ensures this (see zutil.c). To reduce memory
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requirements and avoid any allocation of 64K objects, at the expense of
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compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
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The fields total_in and total_out can be used for statistics or
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progress reports. After compression, total_in holds the total size of
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the uncompressed data and may be saved for use in the decompressor
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(particularly if the decompressor wants to decompress everything in
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#define Z_PARTIAL_FLUSH 1
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#define Z_SYNC_FLUSH 2
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#define Z_FULL_FLUSH 3
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/* Allowed flush values; see deflate() below for details */
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#define Z_STREAM_END 1
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#define Z_NEED_DICT 2
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#define Z_STREAM_ERROR (-2)
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#define Z_DATA_ERROR (-3)
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#define Z_MEM_ERROR (-4)
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#define Z_BUF_ERROR (-5)
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#define Z_VERSION_ERROR (-6)
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/* Return codes for the compression/decompression functions. Negative
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* values are errors, positive values are used for special but normal events.
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#define Z_NO_COMPRESSION 0
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#define Z_BEST_SPEED 1
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#define Z_BEST_COMPRESSION 9
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#define Z_DEFAULT_COMPRESSION (-1)
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/* compression levels */
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#define Z_HUFFMAN_ONLY 2
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#define Z_DEFAULT_STRATEGY 0
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/* compression strategy; see deflateInit2() below for details */
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/* Possible values of the data_type field */
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/* The deflate compression method (the only one supported in this version) */
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#define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
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#define zlib_version zlibVersion()
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/* for compatibility with versions < 1.0.2 */
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/* basic functions */
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extern const char * EXPORT zlibVersion OF((void));
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/* The application can compare zlibVersion and ZLIB_VERSION for consistency.
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If the first character differs, the library code actually used is
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not compatible with the zlib.h header file used by the application.
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This check is automatically made by deflateInit and inflateInit.
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extern int EXPORT deflateInit OF((z_streamp strm, int level));
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Initializes the internal stream state for compression. The fields
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zalloc, zfree and opaque must be initialized before by the caller.
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If zalloc and zfree are set to Z_NULL, deflateInit updates them to
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use default allocation functions.
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The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
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1 gives best speed, 9 gives best compression, 0 gives no compression at
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all (the input data is simply copied a block at a time).
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Z_DEFAULT_COMPRESSION requests a default compromise between speed and
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compression (currently equivalent to level 6).
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deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
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enough memory, Z_STREAM_ERROR if level is not a valid compression level,
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Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
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with the version assumed by the caller (ZLIB_VERSION).
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msg is set to null if there is no error message. deflateInit does not
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perform any compression: this will be done by deflate().
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extern int EXPORT deflate OF((z_streamp strm, int flush));
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Performs one or both of the following actions:
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- Compress more input starting at next_in and update next_in and avail_in
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accordingly. If not all input can be processed (because there is not
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enough room in the output buffer), next_in and avail_in are updated and
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processing will resume at this point for the next call of deflate().
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- Provide more output starting at next_out and update next_out and avail_out
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accordingly. This action is forced if the parameter flush is non zero.
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Forcing flush frequently degrades the compression ratio, so this parameter
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should be set only when necessary (in interactive applications).
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Some output may be provided even if flush is not set.
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Before the call of deflate(), the application should ensure that at least
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one of the actions is possible, by providing more input and/or consuming
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more output, and updating avail_in or avail_out accordingly; avail_out
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should never be zero before the call. The application can consume the
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compressed output when it wants, for example when the output buffer is full
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(avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
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and with zero avail_out, it must be called again after making room in the
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output buffer because there might be more output pending.
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If the parameter flush is set to Z_PARTIAL_FLUSH, the current compression
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block is terminated and flushed to the output buffer so that the
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decompressor can get all input data available so far. For method 9, a future
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variant on method 8, the current block will be flushed but not terminated.
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Z_SYNC_FLUSH has the same effect as partial flush except that the compressed
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output is byte aligned (the compressor can clear its internal bit buffer)
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and the current block is always terminated; this can be useful if the
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compressor has to be restarted from scratch after an interruption (in which
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case the internal state of the compressor may be lost).
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If flush is set to Z_FULL_FLUSH, the compression block is terminated, a
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special marker is output and the compression dictionary is discarded; this
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is useful to allow the decompressor to synchronize if one compressed block
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has been damaged (see inflateSync below). Flushing degrades compression and
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so should be used only when necessary. Using Z_FULL_FLUSH too often can
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seriously degrade the compression. If deflate returns with avail_out == 0,
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this function must be called again with the same value of the flush
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parameter and more output space (updated avail_out), until the flush is
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complete (deflate returns with non-zero avail_out).
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If the parameter flush is set to Z_FINISH, pending input is processed,
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pending output is flushed and deflate returns with Z_STREAM_END if there
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was enough output space; if deflate returns with Z_OK, this function must be
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called again with Z_FINISH and more output space (updated avail_out) but no
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more input data, until it returns with Z_STREAM_END or an error. After
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deflate has returned Z_STREAM_END, the only possible operations on the
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stream are deflateReset or deflateEnd.
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Z_FINISH can be used immediately after deflateInit if all the compression
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is to be done in a single step. In this case, avail_out must be at least
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0.1% larger than avail_in plus 12 bytes. If deflate does not return
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Z_STREAM_END, then it must be called again as described above.
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deflate() may update data_type if it can make a good guess about
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the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
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binary. This field is only for information purposes and does not affect
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the compression algorithm in any manner.
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deflate() returns Z_OK if some progress has been made (more input
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processed or more output produced), Z_STREAM_END if all input has been
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consumed and all output has been produced (only when flush is set to
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Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
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if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible.
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extern int EXPORT deflateEnd OF((z_streamp strm));
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All dynamically allocated data structures for this stream are freed.
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This function discards any unprocessed input and does not flush any
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deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
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stream state was inconsistent, Z_DATA_ERROR if the stream was freed
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prematurely (some input or output was discarded). In the error case,
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msg may be set but then points to a static string (which must not be
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extern int EXPORT inflateInit OF((z_streamp strm));
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Initializes the internal stream state for decompression. The fields
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zalloc, zfree and opaque must be initialized before by the caller. If
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zalloc and zfree are set to Z_NULL, inflateInit updates them to use default
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allocation functions.
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inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
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enough memory, Z_VERSION_ERROR if the zlib library version is incompatible
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with the version assumed by the caller. msg is set to null if there is no
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error message. inflateInit does not perform any decompression: this will be
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extern int EXPORT inflate OF((z_streamp strm, int flush));
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Performs one or both of the following actions:
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- Decompress more input starting at next_in and update next_in and avail_in
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accordingly. If not all input can be processed (because there is not
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enough room in the output buffer), next_in is updated and processing
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will resume at this point for the next call of inflate().
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- Provide more output starting at next_out and update next_out and avail_out
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accordingly. inflate() provides as much output as possible, until there
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is no more input data or no more space in the output buffer (see below
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about the flush parameter).
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Before the call of inflate(), the application should ensure that at least
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one of the actions is possible, by providing more input and/or consuming
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more output, and updating the next_* and avail_* values accordingly.
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The application can consume the uncompressed output when it wants, for
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example when the output buffer is full (avail_out == 0), or after each
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call of inflate(). If inflate returns Z_OK and with zero avail_out, it
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must be called again after making room in the output buffer because there
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might be more output pending.
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If the parameter flush is set to Z_PARTIAL_FLUSH, inflate flushes as much
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output as possible to the output buffer. The flushing behavior of inflate is
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not specified for values of the flush parameter other than Z_PARTIAL_FLUSH
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and Z_FINISH, but the current implementation actually flushes as much output
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inflate() should normally be called until it returns Z_STREAM_END or an
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error. However if all decompression is to be performed in a single step
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(a single call of inflate), the parameter flush should be set to
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Z_FINISH. In this case all pending input is processed and all pending
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output is flushed; avail_out must be large enough to hold all the
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uncompressed data. (The size of the uncompressed data may have been saved
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by the compressor for this purpose.) The next operation on this stream must
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be inflateEnd to deallocate the decompression state. The use of Z_FINISH
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is never required, but can be used to inform inflate that a faster routine
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may be used for the single inflate() call.
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inflate() returns Z_OK if some progress has been made (more input
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processed or more output produced), Z_STREAM_END if the end of the
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compressed data has been reached and all uncompressed output has been
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produced, Z_NEED_DICT if a preset dictionary is needed at this point (see
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inflateSetDictionary below), Z_DATA_ERROR if the input data was corrupted,
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Z_STREAM_ERROR if the stream structure was inconsistent (for example if
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next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
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Z_BUF_ERROR if no progress is possible or if there was not enough room in
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the output buffer when Z_FINISH is used. In the Z_DATA_ERROR case, the
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application may then call inflateSync to look for a good compression block.
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In the Z_NEED_DICT case, strm->adler is set to the Adler32 value of the
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dictionary chosen by the compressor.
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extern int EXPORT inflateEnd OF((z_streamp strm));
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All dynamically allocated data structures for this stream are freed.
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This function discards any unprocessed input and does not flush any
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inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
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was inconsistent. In the error case, msg may be set but then points to a
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static string (which must not be deallocated).
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/* Advanced functions */
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The following functions are needed only in some special applications.
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extern int EXPORT deflateInit2 OF((z_streamp strm,
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This is another version of deflateInit with more compression options. The
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fields next_in, zalloc, zfree and opaque must be initialized before by
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The method parameter is the compression method. It must be Z_DEFLATED in
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this version of the library. (Method 9 will allow a 64K history buffer and
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partial block flushes.)
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The windowBits parameter is the base two logarithm of the window size
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(the size of the history buffer). It should be in the range 8..15 for this
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version of the library (the value 16 will be allowed for method 9). Larger
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values of this parameter result in better compression at the expense of
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memory usage. The default value is 15 if deflateInit is used instead.
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The memLevel parameter specifies how much memory should be allocated
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for the internal compression state. memLevel=1 uses minimum memory but
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is slow and reduces compression ratio; memLevel=9 uses maximum memory
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for optimal speed. The default value is 8. See zconf.h for total memory
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usage as a function of windowBits and memLevel.
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The strategy parameter is used to tune the compression algorithm. Use the
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value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
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filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
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string match). Filtered data consists mostly of small values with a
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somewhat random distribution. In this case, the compression algorithm is
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tuned to compress them better. The effect of Z_FILTERED is to force more
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Huffman coding and less string matching; it is somewhat intermediate
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between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
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the compression ratio but not the correctness of the compressed output even
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if it is not set appropriately.
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If next_in is not null, the library will use this buffer to hold also
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some history information; the buffer must either hold the entire input
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data, or have at least 1<<(windowBits+1) bytes and be writable. If next_in
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is null, the library will allocate its own history buffer (and leave next_in
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null). next_out need not be provided here but must be provided by the
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application for the next call of deflate().
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If the history buffer is provided by the application, next_in must
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must never be changed by the application since the compressor maintains
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information inside this buffer from call to call; the application
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must provide more input only by increasing avail_in. next_in is always
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reset by the library in this case.
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deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
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not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
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an invalid method). msg is set to null if there is no error message.
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deflateInit2 does not perform any compression: this will be done by
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extern int EXPORT deflateSetDictionary OF((z_streamp strm,
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const Bytef *dictionary,
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Initializes the compression dictionary (history buffer) from the given
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byte sequence without producing any compressed output. This function must
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be called immediately after deflateInit or deflateInit2, before any call
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of deflate. The compressor and decompressor must use exactly the same
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dictionary (see inflateSetDictionary).
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The dictionary should consist of strings (byte sequences) that are likely
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to be encountered later in the data to be compressed, with the most commonly
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used strings preferably put towards the end of the dictionary. Using a
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dictionary is most useful when the data to be compressed is short and
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can be predicted with good accuracy; the data can then be compressed better
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than with the default empty dictionary. In this version of the library,
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only the last 32K bytes of the dictionary are used.
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Upon return of this function, strm->adler is set to the Adler32 value
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of the dictionary; the decompressor may later use this value to determine
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which dictionary has been used by the compressor. (The Adler32 value
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applies to the whole dictionary even if only a subset of the dictionary is
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actually used by the compressor.)
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deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
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parameter is invalid (such as NULL dictionary) or the stream state
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is inconsistent (for example if deflate has already been called for this
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stream). deflateSetDictionary does not perform any compression: this will
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be done by deflate().
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extern int EXPORT deflateCopy OF((z_streamp dest,
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Sets the destination stream as a complete copy of the source stream. If
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the source stream is using an application-supplied history buffer, a new
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buffer is allocated for the destination stream. The compressed output
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buffer is always application-supplied. It's the responsibility of the
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application to provide the correct values of next_out and avail_out for the
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next call of deflate.
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This function can be useful when several compression strategies will be
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tried, for example when there are several ways of pre-processing the input
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data with a filter. The streams that will be discarded should then be freed
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by calling deflateEnd. Note that deflateCopy duplicates the internal
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compression state which can be quite large, so this strategy is slow and
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can consume lots of memory.
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deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
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enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
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(such as zalloc being NULL). msg is left unchanged in both source and
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extern int EXPORT deflateReset OF((z_streamp strm));
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This function is equivalent to deflateEnd followed by deflateInit,
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but does not free and reallocate all the internal compression state.
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The stream will keep the same compression level and any other attributes
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that may have been set by deflateInit2.
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deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
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stream state was inconsistent (such as zalloc or state being NULL).
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extern int EXPORT deflateParams OF((z_streamp strm, int level, int strategy));
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Dynamically update the compression level and compression strategy.
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This can be used to switch between compression and straight copy of
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the input data, or to switch to a different kind of input data requiring
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a different strategy. If the compression level is changed, the input
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available so far is compressed with the old level (and may be flushed);
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the new level will take effect only at the next call of deflate().
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Before the call of deflateParams, the stream state must be set as for
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a call of deflate(), since the currently available input may have to
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be compressed and flushed. In particular, strm->avail_out must be non-zero.
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deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
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stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
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if strm->avail_out was zero.
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extern int EXPORT inflateInit2 OF((z_streamp strm,
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This is another version of inflateInit with more compression options. The
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fields next_out, zalloc, zfree and opaque must be initialized before by
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The windowBits parameter is the base two logarithm of the maximum window
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size (the size of the history buffer). It should be in the range 8..15 for
524
this version of the library (the value 16 will be allowed soon). The
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default value is 15 if inflateInit is used instead. If a compressed stream
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with a larger window size is given as input, inflate() will return with
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the error code Z_DATA_ERROR instead of trying to allocate a larger window.
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If next_out is not null, the library will use this buffer for the history
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buffer; the buffer must either be large enough to hold the entire output
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data, or have at least 1<<windowBits bytes. If next_out is null, the
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library will allocate its own buffer (and leave next_out null). next_in
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need not be provided here but must be provided by the application for the
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next call of inflate().
536
If the history buffer is provided by the application, next_out must
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never be changed by the application since the decompressor maintains
538
history information inside this buffer from call to call; the application
539
can only reset next_out to the beginning of the history buffer when
540
avail_out is zero and all output has been consumed.
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inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
543
not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
544
windowBits < 8). msg is set to null if there is no error message.
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inflateInit2 does not perform any decompression: this will be done by
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extern int EXPORT inflateSetDictionary OF((z_streamp strm,
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const Bytef *dictionary,
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Initializes the decompression dictionary (history buffer) from the given
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uncompressed byte sequence. This function must be called immediately after
555
a call of inflate if this call returned Z_NEED_DICT. The dictionary chosen
556
by the compressor can be determined from the Adler32 value returned by this
557
call of inflate. The compressor and decompressor must use exactly the same
558
dictionary (see deflateSetDictionary).
560
inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
561
parameter is invalid (such as NULL dictionary) or the stream state is
562
inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
563
expected one (incorrect Adler32 value). inflateSetDictionary does not
564
perform any decompression: this will be done by subsequent calls of
568
extern int EXPORT inflateSync OF((z_streamp strm));
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Skips invalid compressed data until the special marker (see deflate()
571
above) can be found, or until all available input is skipped. No output
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inflateSync returns Z_OK if the special marker has been found, Z_BUF_ERROR
575
if no more input was provided, Z_DATA_ERROR if no marker has been found,
576
or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
577
case, the application may save the current current value of total_in which
578
indicates where valid compressed data was found. In the error case, the
579
application may repeatedly call inflateSync, providing more input each time,
580
until success or end of the input data.
583
extern int EXPORT inflateReset OF((z_streamp strm));
585
This function is equivalent to inflateEnd followed by inflateInit,
586
but does not free and reallocate all the internal decompression state.
587
The stream will keep attributes that may have been set by inflateInit2.
589
inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
590
stream state was inconsistent (such as zalloc or state being NULL).
594
/* utility functions */
597
The following utility functions are implemented on top of the
598
basic stream-oriented functions. To simplify the interface, some
599
default options are assumed (compression level, window size,
600
standard memory allocation functions). The source code of these
601
utility functions can easily be modified if you need special options.
604
extern int EXPORT compress OF((Bytef *dest, uLongf *destLen,
605
const Bytef *source, uLong sourceLen));
607
Compresses the source buffer into the destination buffer. sourceLen is
608
the byte length of the source buffer. Upon entry, destLen is the total
609
size of the destination buffer, which must be at least 0.1% larger than
610
sourceLen plus 12 bytes. Upon exit, destLen is the actual size of the
612
This function can be used to compress a whole file at once if the
613
input file is mmap'ed.
614
compress returns Z_OK if success, Z_MEM_ERROR if there was not
615
enough memory, Z_BUF_ERROR if there was not enough room in the output
619
extern int EXPORT uncompress OF((Bytef *dest, uLongf *destLen,
620
const Bytef *source, uLong sourceLen));
622
Decompresses the source buffer into the destination buffer. sourceLen is
623
the byte length of the source buffer. Upon entry, destLen is the total
624
size of the destination buffer, which must be large enough to hold the
625
entire uncompressed data. (The size of the uncompressed data must have
626
been saved previously by the compressor and transmitted to the decompressor
627
by some mechanism outside the scope of this compression library.)
628
Upon exit, destLen is the actual size of the compressed buffer.
629
This function can be used to decompress a whole file at once if the
630
input file is mmap'ed.
632
uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
633
enough memory, Z_BUF_ERROR if there was not enough room in the output
634
buffer, or Z_DATA_ERROR if the input data was corrupted.
638
typedef voidp gzFile;
640
extern gzFile EXPORT gzopen OF((const char *path, const char *mode));
642
Opens a gzip (.gz) file for reading or writing. The mode parameter
643
is as in fopen ("rb" or "wb") but can also include a compression level
644
("wb9"). gzopen can be used to read a file which is not in gzip format;
645
in this case gzread will directly read from the file without decompression.
646
gzopen returns NULL if the file could not be opened or if there was
647
insufficient memory to allocate the (de)compression state; errno
648
can be checked to distinguish the two cases (if errno is zero, the
649
zlib error is Z_MEM_ERROR).
652
extern gzFile EXPORT gzdopen OF((int fd, const char *mode));
654
gzdopen() associates a gzFile with the file descriptor fd. File
655
descriptors are obtained from calls like open, dup, creat, pipe or
656
fileno (in the file has been previously opened with fopen).
657
The mode parameter is as in gzopen.
658
The next call of gzclose on the returned gzFile will also close the
659
file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
660
descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
661
gzdopen returns NULL if there was insufficient memory to allocate
662
the (de)compression state.
665
extern int EXPORT gzread OF((gzFile file, voidp buf, unsigned len));
667
Reads the given number of uncompressed bytes from the compressed file.
668
If the input file was not in gzip format, gzread copies the given number
669
of bytes into the buffer.
670
gzread returns the number of uncompressed bytes actually read (0 for
671
end of file, -1 for error). */
673
extern int EXPORT gzwrite OF((gzFile file, const voidp buf, unsigned len));
675
Writes the given number of uncompressed bytes into the compressed file.
676
gzwrite returns the number of uncompressed bytes actually written
677
(0 in case of error).
680
extern int EXPORT gzflush OF((gzFile file, int flush));
682
Flushes all pending output into the compressed file. The parameter
683
flush is as in the deflate() function. The return value is the zlib
684
error number (see function gzerror below). gzflush returns Z_OK if
685
the flush parameter is Z_FINISH and all output could be flushed.
686
gzflush should be called only when strictly necessary because it can
690
extern int EXPORT gzclose OF((gzFile file));
692
Flushes all pending output if necessary, closes the compressed file
693
and deallocates all the (de)compression state. The return value is the zlib
694
error number (see function gzerror below).
697
extern const char * EXPORT gzerror OF((gzFile file, int *errnum));
699
Returns the error message for the last error which occurred on the
700
given compressed file. errnum is set to zlib error number. If an
701
error occurred in the file system and not in the compression library,
702
errnum is set to Z_ERRNO and the application may consult errno
703
to get the exact error code.
706
/* checksum functions */
709
These functions are not related to compression but are exported
710
anyway because they might be useful in applications using the
714
extern uLong EXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
717
Update a running Adler-32 checksum with the bytes buf[0..len-1] and
718
return the updated checksum. If buf is NULL, this function returns
719
the required initial value for the checksum.
720
An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
721
much faster. Usage example:
723
uLong adler = adler32(0L, Z_NULL, 0);
725
while (read_buffer(buffer, length) != EOF) {
726
adler = adler32(adler, buffer, length);
728
if (adler != original_adler) error();
731
extern uLong EXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
733
Update a running crc with the bytes buf[0..len-1] and return the updated
734
crc. If buf is NULL, this function returns the required initial value
735
for the crc. Pre- and post-conditioning (one's complement) is performed
736
within this function so it shouldn't be done by the application.
739
uLong crc = crc32(0L, Z_NULL, 0);
741
while (read_buffer(buffer, length) != EOF) {
742
crc = crc32(crc, buffer, length);
744
if (crc != original_crc) error();
748
/* various hacks, don't look :) */
750
/* deflateInit and inflateInit are macros to allow checking the zlib version
751
* and the compiler's view of z_stream:
753
extern int EXPORT deflateInit_ OF((z_streamp strm, int level,
754
const char *version, int stream_size));
755
extern int EXPORT inflateInit_ OF((z_streamp strm,
756
const char *version, int stream_size));
757
extern int EXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
758
int windowBits, int memLevel, int strategy,
759
const char *version, int stream_size));
760
extern int EXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
761
const char *version, int stream_size));
762
#define deflateInit(strm, level) \
763
deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream))
764
#define inflateInit(strm) \
765
inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream))
766
#define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
767
deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
768
(strategy), ZLIB_VERSION, sizeof(z_stream))
769
#define inflateInit2(strm, windowBits) \
770
inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
772
#if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL)
773
struct internal_state {int dummy;}; /* hack for buggy compilers */
776
uLongf *get_crc_table OF((void)); /* can be used by asm versions of crc32() */
added
removed
zlib/zlib.h~
