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/* zlib.h -- interface of the 'zlib' general purpose compression library
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version 1.1.4, March 11th, 2002
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Copyright (C) 1995-2002 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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jloup@gzip.org 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 "1.1.4"
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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 will be added later and will have the same
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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 also supports reading and writing files in gzip (.gz) format
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with an interface similar to that of stdio.
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The library does not install any signal handler. The decoder checks
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the consistency of the compressed data, so the library should never
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crash even in case 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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If zlib is used in a multi-threaded application, zalloc and zfree must be
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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 /* will be removed, use Z_SYNC_FLUSH instead */
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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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ZEXTERN const char * ZEXPORT 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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ZEXTERN int ZEXPORT 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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ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
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deflate compresses as much data as possible, and stops when the input
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buffer becomes empty or the output buffer becomes full. It may introduce some
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output latency (reading input without producing any output) except when
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The detailed semantics are as follows. deflate performs one or both of the
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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_SYNC_FLUSH, all pending output is
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flushed to the output buffer and the output is aligned on a byte boundary, so
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that the decompressor can get all input data available so far. (In particular
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avail_in is zero after the call if enough output space has been provided
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before the call.) Flushing may degrade compression for some compression
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algorithms and so it should be used only when necessary.
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If flush is set to Z_FULL_FLUSH, all output is flushed as with
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Z_SYNC_FLUSH, and the compression state is reset so that decompression can
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restart from this point if previous compressed data has been damaged or if
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random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
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If deflate returns with avail_out == 0, this function must be called again
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with the same value of the flush parameter and more output space (updated
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avail_out), until the flush is complete (deflate returns with non-zero
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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() sets strm->adler to the adler32 checksum of all input read
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so far (that is, total_in bytes).
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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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(for example avail_in or avail_out was zero).
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ZEXTERN int ZEXPORT 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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ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
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Initializes the internal stream state for decompression. The fields
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next_in, avail_in, zalloc, zfree and opaque must be initialized before by
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the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
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value depends on the compression method), inflateInit determines the
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compression method from the zlib header and allocates all data structures
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accordingly; otherwise the allocation will be deferred to the first call of
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inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to
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use default allocation functions.
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inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
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memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
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version assumed by the caller. msg is set to null if there is no error
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message. inflateInit does not perform any decompression apart from reading
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the zlib header if present: this will be done by inflate(). (So next_in and
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avail_in may be modified, but next_out and avail_out are unchanged.)
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ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
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inflate decompresses as much data as possible, and stops when the input
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buffer becomes empty or the output buffer becomes full. It may some
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introduce some output latency (reading input without producing any output)
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except when forced to flush.
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The detailed semantics are as follows. inflate performs one or both of the
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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_SYNC_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_SYNC_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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If a preset dictionary is needed at this point (see inflateSetDictionary
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below), inflate sets strm-adler to the adler32 checksum of the
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dictionary chosen by the compressor and returns Z_NEED_DICT; otherwise
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it sets strm->adler to the adler32 checksum of all output produced
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so far (that is, total_out bytes) and returns Z_OK, Z_STREAM_END or
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an error code as described below. At the end of the stream, inflate()
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checks that its computed adler32 checksum is equal to that saved by the
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compressor and returns Z_STREAM_END only if the checksum is correct.
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inflate() returns Z_OK if some progress has been made (more input processed
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or more output produced), Z_STREAM_END if the end of the compressed data has
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been reached and all uncompressed output has been produced, Z_NEED_DICT if a
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preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
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corrupted (input stream not conforming to the zlib format or incorrect
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adler32 checksum), Z_STREAM_ERROR if the stream structure was inconsistent
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(for example if next_in or next_out was NULL), Z_MEM_ERROR if there was not
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enough memory, Z_BUF_ERROR if no progress is possible or if there was not
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enough room in the output buffer when Z_FINISH is used. In the Z_DATA_ERROR
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case, the application may then call inflateSync to look for a good
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ZEXTERN int ZEXPORT 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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ZEXTERN int ZEXPORT 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.
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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. Larger values of this parameter result in better
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compression at the expense of memory usage. The default value is 15 if
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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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deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
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memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
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method). msg is set to null if there is no error message. deflateInit2 does
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not perform any compression: this will be done by deflate().
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ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
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const Bytef *dictionary,
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Initializes the compression dictionary from the given byte sequence
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without producing any compressed output. This function must be called
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immediately after deflateInit, deflateInit2 or deflateReset, before any
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call 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 can be
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predicted with good accuracy; the data can then be compressed better than
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with the default empty dictionary.
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Depending on the size of the compression data structures selected by
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deflateInit or deflateInit2, a part of the dictionary may in effect be
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discarded, for example if the dictionary is larger than the window size in
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deflate or deflate2. Thus the strings most likely to be useful should be
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put at the end of the dictionary, not at the front.
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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 is
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inconsistent (for example if deflate has already been called for this stream
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or if the compression method is bsort). deflateSetDictionary does not
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perform any compression: this will be done by deflate().
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ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
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Sets the destination stream as a complete copy of the source stream.
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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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ZEXTERN int ZEXPORT 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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ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
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Dynamically update the compression level and compression strategy. The
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interpretation of level and strategy is as in deflateInit2. This can be
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used to switch between compression and straight copy of the input data, or
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to switch to a different kind of input data requiring a different
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strategy. If the compression level is changed, the input available so far
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is compressed with the old level (and may be flushed); the new level will
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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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ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
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This is another version of inflateInit with an extra parameter. The
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fields next_in, avail_in, zalloc, zfree and opaque must be initialized
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before by the caller.
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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
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this version of the library. The default value is 15 if inflateInit is used
541
instead. If a compressed stream with a larger window size is given as
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input, inflate() will return with the error code Z_DATA_ERROR instead of
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trying to allocate a larger window.
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inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
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memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative
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memLevel). msg is set to null if there is no error message. inflateInit2
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does not perform any decompression apart from reading the zlib header if
549
present: this will be done by inflate(). (So next_in and avail_in may be
550
modified, but next_out and avail_out are unchanged.)
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ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
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const Bytef *dictionary,
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Initializes the decompression dictionary from the given uncompressed byte
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sequence. This function must be called immediately after a call of inflate
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if this call returned Z_NEED_DICT. The dictionary chosen by the compressor
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can be determined from the Adler32 value returned by this call of
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inflate. The compressor and decompressor must use exactly the same
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dictionary (see deflateSetDictionary).
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inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
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parameter is invalid (such as NULL dictionary) or the stream state is
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inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
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expected one (incorrect Adler32 value). inflateSetDictionary does not
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perform any decompression: this will be done by subsequent calls of
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ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
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Skips invalid compressed data until a full flush point (see above the
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description of deflate with Z_FULL_FLUSH) can be found, or until all
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available input is skipped. No output is provided.
578
inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
579
if no more input was provided, Z_DATA_ERROR if no flush point has been found,
580
or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
581
case, the application may save the current current value of total_in which
582
indicates where valid compressed data was found. In the error case, the
583
application may repeatedly call inflateSync, providing more input each time,
584
until success or end of the input data.
587
ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
589
This function is equivalent to inflateEnd followed by inflateInit,
590
but does not free and reallocate all the internal decompression state.
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The stream will keep attributes that may have been set by inflateInit2.
593
inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
594
stream state was inconsistent (such as zalloc or state being NULL).
598
/* utility functions */
601
The following utility functions are implemented on top of the
602
basic stream-oriented functions. To simplify the interface, some
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default options are assumed (compression level and memory usage,
604
standard memory allocation functions). The source code of these
605
utility functions can easily be modified if you need special options.
608
ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
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const Bytef *source, uLong sourceLen));
611
Compresses the source buffer into the destination buffer. sourceLen is
612
the byte length of the source buffer. Upon entry, destLen is the total
613
size of the destination buffer, which must be at least 0.1% larger than
614
sourceLen plus 12 bytes. Upon exit, destLen is the actual size of the
616
This function can be used to compress a whole file at once if the
617
input file is mmap'ed.
618
compress returns Z_OK if success, Z_MEM_ERROR if there was not
619
enough memory, Z_BUF_ERROR if there was not enough room in the output
623
ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
624
const Bytef *source, uLong sourceLen,
627
Compresses the source buffer into the destination buffer. The level
628
parameter has the same meaning as in deflateInit. sourceLen is the byte
629
length of the source buffer. Upon entry, destLen is the total size of the
630
destination buffer, which must be at least 0.1% larger than sourceLen plus
631
12 bytes. Upon exit, destLen is the actual size of the compressed buffer.
633
compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
634
memory, Z_BUF_ERROR if there was not enough room in the output buffer,
635
Z_STREAM_ERROR if the level parameter is invalid.
638
ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
639
const Bytef *source, uLong sourceLen));
641
Decompresses the source buffer into the destination buffer. sourceLen is
642
the byte length of the source buffer. Upon entry, destLen is the total
643
size of the destination buffer, which must be large enough to hold the
644
entire uncompressed data. (The size of the uncompressed data must have
645
been saved previously by the compressor and transmitted to the decompressor
646
by some mechanism outside the scope of this compression library.)
647
Upon exit, destLen is the actual size of the compressed buffer.
648
This function can be used to decompress a whole file at once if the
649
input file is mmap'ed.
651
uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
652
enough memory, Z_BUF_ERROR if there was not enough room in the output
653
buffer, or Z_DATA_ERROR if the input data was corrupted.
657
typedef voidp gzFile;
659
ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
661
Opens a gzip (.gz) file for reading or writing. The mode parameter
662
is as in fopen ("rb" or "wb") but can also include a compression level
663
("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
664
Huffman only compression as in "wb1h". (See the description
665
of deflateInit2 for more information about the strategy parameter.)
667
gzopen can be used to read a file which is not in gzip format; in this
668
case gzread will directly read from the file without decompression.
670
gzopen returns NULL if the file could not be opened or if there was
671
insufficient memory to allocate the (de)compression state; errno
672
can be checked to distinguish the two cases (if errno is zero, the
673
zlib error is Z_MEM_ERROR). */
675
ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
677
gzdopen() associates a gzFile with the file descriptor fd. File
678
descriptors are obtained from calls like open, dup, creat, pipe or
679
fileno (in the file has been previously opened with fopen).
680
The mode parameter is as in gzopen.
681
The next call of gzclose on the returned gzFile will also close the
682
file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
683
descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
684
gzdopen returns NULL if there was insufficient memory to allocate
685
the (de)compression state.
688
ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
690
Dynamically update the compression level or strategy. See the description
691
of deflateInit2 for the meaning of these parameters.
692
gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
696
ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
698
Reads the given number of uncompressed bytes from the compressed file.
699
If the input file was not in gzip format, gzread copies the given number
700
of bytes into the buffer.
701
gzread returns the number of uncompressed bytes actually read (0 for
702
end of file, -1 for error). */
704
ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
705
const voidp buf, unsigned len));
707
Writes the given number of uncompressed bytes into the compressed file.
708
gzwrite returns the number of uncompressed bytes actually written
709
(0 in case of error).
712
ZEXTERN int ZEXPORTVA gzprintf OF((gzFile file, const char *format, ...));
714
Converts, formats, and writes the args to the compressed file under
715
control of the format string, as in fprintf. gzprintf returns the number of
716
uncompressed bytes actually written (0 in case of error).
719
ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
721
Writes the given null-terminated string to the compressed file, excluding
722
the terminating null character.
723
gzputs returns the number of characters written, or -1 in case of error.
726
ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
728
Reads bytes from the compressed file until len-1 characters are read, or
729
a newline character is read and transferred to buf, or an end-of-file
730
condition is encountered. The string is then terminated with a null
732
gzgets returns buf, or Z_NULL in case of error.
735
ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
737
Writes c, converted to an unsigned char, into the compressed file.
738
gzputc returns the value that was written, or -1 in case of error.
741
ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
743
Reads one byte from the compressed file. gzgetc returns this byte
744
or -1 in case of end of file or error.
747
ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
749
Flushes all pending output into the compressed file. The parameter
750
flush is as in the deflate() function. The return value is the zlib
751
error number (see function gzerror below). gzflush returns Z_OK if
752
the flush parameter is Z_FINISH and all output could be flushed.
753
gzflush should be called only when strictly necessary because it can
757
ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
758
z_off_t offset, int whence));
760
Sets the starting position for the next gzread or gzwrite on the
761
given compressed file. The offset represents a number of bytes in the
762
uncompressed data stream. The whence parameter is defined as in lseek(2);
763
the value SEEK_END is not supported.
764
If the file is opened for reading, this function is emulated but can be
765
extremely slow. If the file is opened for writing, only forward seeks are
766
supported; gzseek then compresses a sequence of zeroes up to the new
769
gzseek returns the resulting offset location as measured in bytes from
770
the beginning of the uncompressed stream, or -1 in case of error, in
771
particular if the file is opened for writing and the new starting position
772
would be before the current position.
775
ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
777
Rewinds the given file. This function is supported only for reading.
779
gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
782
ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
784
Returns the starting position for the next gzread or gzwrite on the
785
given compressed file. This position represents a number of bytes in the
786
uncompressed data stream.
788
gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
791
ZEXTERN int ZEXPORT gzeof OF((gzFile file));
793
Returns 1 when EOF has previously been detected reading the given
794
input stream, otherwise zero.
797
ZEXTERN int ZEXPORT gzclose OF((gzFile file));
799
Flushes all pending output if necessary, closes the compressed file
800
and deallocates all the (de)compression state. The return value is the zlib
801
error number (see function gzerror below).
804
ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
806
Returns the error message for the last error which occurred on the
807
given compressed file. errnum is set to zlib error number. If an
808
error occurred in the file system and not in the compression library,
809
errnum is set to Z_ERRNO and the application may consult errno
810
to get the exact error code.
813
/* checksum functions */
816
These functions are not related to compression but are exported
817
anyway because they might be useful in applications using the
821
ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
824
Update a running Adler-32 checksum with the bytes buf[0..len-1] and
825
return the updated checksum. If buf is NULL, this function returns
826
the required initial value for the checksum.
827
An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
828
much faster. Usage example:
830
uLong adler = adler32(0L, Z_NULL, 0);
832
while (read_buffer(buffer, length) != EOF) {
833
adler = adler32(adler, buffer, length);
835
if (adler != original_adler) error();
838
ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
840
Update a running crc with the bytes buf[0..len-1] and return the updated
841
crc. If buf is NULL, this function returns the required initial value
842
for the crc. Pre- and post-conditioning (one's complement) is performed
843
within this function so it shouldn't be done by the application.
846
uLong crc = crc32(0L, Z_NULL, 0);
848
while (read_buffer(buffer, length) != EOF) {
849
crc = crc32(crc, buffer, length);
851
if (crc != original_crc) error();
855
/* various hacks, don't look :) */
857
/* deflateInit and inflateInit are macros to allow checking the zlib version
858
* and the compiler's view of z_stream:
860
ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
861
const char *version, int stream_size));
862
ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
863
const char *version, int stream_size));
864
ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
865
int windowBits, int memLevel,
866
int strategy, const char *version,
868
ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
869
const char *version, int stream_size));
870
#define deflateInit(strm, level) \
871
deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream))
872
#define inflateInit(strm) \
873
inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream))
874
#define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
875
deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
876
(strategy), ZLIB_VERSION, sizeof(z_stream))
877
#define inflateInit2(strm, windowBits) \
878
inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
881
#if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL)
882
struct internal_state {int dummy;}; /* hack for buggy compilers */
885
ZEXTERN const char * ZEXPORT zError OF((int err));
886
ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp z));
887
ZEXTERN const uLongf * ZEXPORT get_crc_table OF((void));
added
removed
src/tools/zip/minizip/win32/zlib.h
