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/* zlib.h -- interface of the 'zlib' general purpose compression library
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version 1.2.3, July 18th, 2005
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Copyright (C) 1995-2005 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 http://www.ietf.org/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 "1.2.3.1.Samba"
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#define ZLIB_VERNUM 0x1231
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* Modified for Samba by Stefan Metzmacher <metze@samba.org> 2008
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* inflateReset2() added and compiler warnings fixed
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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 compressed data format used by default by the in-memory functions is
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the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
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around a deflate stream, which is itself documented in RFC 1951.
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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 using the functions that start
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with "gz". The gzip format is different from the zlib format. gzip is a
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gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
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This library can optionally read and write gzip streams in memory as well.
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The zlib format was designed to be compact and fast for use in memory
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and on communications channels. The gzip format was designed for single-
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file compression on file systems, has a larger header than zlib to maintain
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directory information, and uses a different, slower check method than zlib.
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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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const 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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const 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: binary or text */
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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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gzip header information passed to and from zlib routines. See RFC 1952
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for more details on the meanings of these fields.
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typedef struct gz_header_s {
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int text; /* true if compressed data believed to be text */
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uLong time; /* modification time */
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int xflags; /* extra flags (not used when writing a gzip file) */
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int os; /* operating system */
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Bytef *extra; /* pointer to extra field or Z_NULL if none */
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uInt extra_len; /* extra field length (valid if extra != Z_NULL) */
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uInt extra_max; /* space at extra (only when reading header) */
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Bytef *name; /* pointer to zero-terminated file name or Z_NULL */
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uInt name_max; /* space at name (only when reading header) */
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Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */
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uInt comm_max; /* space at comment (only when reading header) */
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int hcrc; /* true if there was or will be a header crc */
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int done; /* true when done reading gzip header (not used
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when writing a gzip file) */
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typedef gz_header FAR *gz_headerp;
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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() and inflate() 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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#define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
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/* Possible values of the data_type field (though see inflate()) */
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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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#if (__GNUC__ >= 3) && (__GNUC_MINOR__ >= 1)
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/** Use gcc attribute to check printf fns. a1 is the 1-based index of
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* the parameter containing the format, and a2 the index of the first
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* argument. Note that some gcc 2.x versions don't handle this
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#define _Z_PRINTF_ATTRIBUTE(a1, a2) __attribute__ ((format (__printf__, a1, a2)))
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#define _Z_PRINTF_ATTRIBUTE(a1, a2)
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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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Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
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decide how much data to accumualte before producing output, in order to
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maximize compression.
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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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avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
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avail_out is greater than six to avoid repeated flush markers due to
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avail_out == 0 on return.
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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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the value returned by deflateBound (see below). 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 strm->data_type if it can make a good guess about
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the input data type (Z_BINARY or Z_TEXT). 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). Note that Z_BUF_ERROR is not
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fatal, and deflate() can be called again with more input and more output
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space to continue compressing.
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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 introduce
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some output latency (reading input without producing any output) except when
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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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The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
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Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
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output as possible to the output buffer. Z_BLOCK requests that inflate() stop
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if and when it gets to the next deflate block boundary. When decoding the
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zlib or gzip format, this will cause inflate() to return immediately after
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the header and before the first block. When doing a raw inflate, inflate()
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will go ahead and process the first block, and will return when it gets to
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the end of that block, or when it runs out of data.
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The Z_BLOCK option assists in appending to or combining deflate streams.
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Also to assist in this, on return inflate() will set strm->data_type to the
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number of unused bits in the last byte taken from strm->next_in, plus 64
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if inflate() is currently decoding the last block in the deflate stream,
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plus 128 if inflate() returned immediately after decoding an end-of-block
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code or decoding the complete header up to just before the first byte of the
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deflate stream. The end-of-block will not be indicated until all of the
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uncompressed data from that block has been written to strm->next_out. The
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number of unused bits may in general be greater than seven, except when
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bit 7 of data_type is set, in which case the number of unused bits will be
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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 approach
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may be used for the single inflate() call.
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In this implementation, inflate() always flushes as much output as
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possible to the output buffer, and always uses the faster approach on the
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first call. So the only effect of the flush parameter in this implementation
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is on the return value of inflate(), as noted below, or when it returns early
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because Z_BLOCK is used.
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If a preset dictionary is needed after this call (see inflateSetDictionary
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below), inflate sets strm->adler to the adler32 checksum of the dictionary
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chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
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strm->adler to the adler32 checksum of all output produced so far (that is,
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total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
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below. At the end of the stream, inflate() checks that its computed adler32
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checksum is equal to that saved by the compressor and returns Z_STREAM_END
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only if the checksum is correct.
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inflate() will decompress and check either zlib-wrapped or gzip-wrapped
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deflate data. The header type is detected automatically. Any information
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contained in the gzip header is not retained, so applications that need that
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information should instead use raw inflate, see inflateInit2() below, or
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inflateBack() and perform their own processing of the gzip header and
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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 check
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value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
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if 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 the
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output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
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inflate() can be called again with more input and more output space to
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continue decompressing. If Z_DATA_ERROR is returned, the application may then
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call inflateSync() to look for a good compression block if a partial recovery
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of the data is desired.
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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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windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
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determines the window size. deflate() will then generate raw deflate data
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with no zlib header or trailer, and will not compute an adler32 check value.
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windowBits can also be greater than 15 for optional gzip encoding. Add
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16 to windowBits to write a simple gzip header and trailer around the
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compressed data instead of a zlib wrapper. The gzip header will have no
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file name, no extra data, no comment, no modification time (set to zero),
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no header crc, and the operating system will be set to 255 (unknown). If a
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gzip stream is being written, strm->adler is a crc32 instead of an adler32.
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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), Z_HUFFMAN_ONLY to force Huffman encoding only (no
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string match), or Z_RLE to limit match distances to one (run-length
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encoding). Filtered data consists mostly of small values with a somewhat
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random distribution. In this case, the compression algorithm is tuned to
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compress them better. The effect of Z_FILTERED is to force more Huffman
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coding and less string matching; it is somewhat intermediate between
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Z_DEFAULT and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as fast as
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Z_HUFFMAN_ONLY, but give better compression for PNG image data. The strategy
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parameter only affects the compression ratio but not the correctness of the
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compressed output even if it is not set appropriately. Z_FIXED prevents the
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use of dynamic Huffman codes, allowing for a simpler decoder for special
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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. In addition, the
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current implementation of deflate will use at most the window size minus
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262 bytes of the provided dictionary.
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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
581
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
583
actually used by the compressor.) If a raw deflate was requested, then the
584
adler32 value is not computed and strm->adler is not set.
586
deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
587
parameter is invalid (such as NULL dictionary) or the stream state is
588
inconsistent (for example if deflate has already been called for this stream
589
or if the compression method is bsort). deflateSetDictionary does not
590
perform any compression: this will be done by deflate().
593
ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
596
Sets the destination stream as a complete copy of the source stream.
598
This function can be useful when several compression strategies will be
599
tried, for example when there are several ways of pre-processing the input
600
data with a filter. The streams that will be discarded should then be freed
601
by calling deflateEnd. Note that deflateCopy duplicates the internal
602
compression state which can be quite large, so this strategy is slow and
603
can consume lots of memory.
605
deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
606
enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
607
(such as zalloc being NULL). msg is left unchanged in both source and
611
ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
613
This function is equivalent to deflateEnd followed by deflateInit,
614
but does not free and reallocate all the internal compression state.
615
The stream will keep the same compression level and any other attributes
616
that may have been set by deflateInit2.
618
deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
619
stream state was inconsistent (such as zalloc or state being NULL).
622
ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
626
Dynamically update the compression level and compression strategy. The
627
interpretation of level and strategy is as in deflateInit2. This can be
628
used to switch between compression and straight copy of the input data, or
629
to switch to a different kind of input data requiring a different
630
strategy. If the compression level is changed, the input available so far
631
is compressed with the old level (and may be flushed); the new level will
632
take effect only at the next call of deflate().
634
Before the call of deflateParams, the stream state must be set as for
635
a call of deflate(), since the currently available input may have to
636
be compressed and flushed. In particular, strm->avail_out must be non-zero.
638
deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
639
stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
640
if strm->avail_out was zero.
643
ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
649
Fine tune deflate's internal compression parameters. This should only be
650
used by someone who understands the algorithm used by zlib's deflate for
651
searching for the best matching string, and even then only by the most
652
fanatic optimizer trying to squeeze out the last compressed bit for their
653
specific input data. Read the deflate.c source code for the meaning of the
654
max_lazy, good_length, nice_length, and max_chain parameters.
656
deflateTune() can be called after deflateInit() or deflateInit2(), and
657
returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
660
ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
663
deflateBound() returns an upper bound on the compressed size after
664
deflation of sourceLen bytes. It must be called after deflateInit()
665
or deflateInit2(). This would be used to allocate an output buffer
666
for deflation in a single pass, and so would be called before deflate().
669
ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
673
deflatePrime() inserts bits in the deflate output stream. The intent
674
is that this function is used to start off the deflate output with the
675
bits leftover from a previous deflate stream when appending to it. As such,
676
this function can only be used for raw deflate, and must be used before the
677
first deflate() call after a deflateInit2() or deflateReset(). bits must be
678
less than or equal to 16, and that many of the least significant bits of
679
value will be inserted in the output.
681
deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
682
stream state was inconsistent.
685
ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
688
deflateSetHeader() provides gzip header information for when a gzip
689
stream is requested by deflateInit2(). deflateSetHeader() may be called
690
after deflateInit2() or deflateReset() and before the first call of
691
deflate(). The text, time, os, extra field, name, and comment information
692
in the provided gz_header structure are written to the gzip header (xflag is
693
ignored -- the extra flags are set according to the compression level). The
694
caller must assure that, if not Z_NULL, name and comment are terminated with
695
a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
696
available there. If hcrc is true, a gzip header crc is included. Note that
697
the current versions of the command-line version of gzip (up through version
698
1.3.x) do not support header crc's, and will report that it is a "multi-part
699
gzip file" and give up.
701
If deflateSetHeader is not used, the default gzip header has text false,
702
the time set to zero, and os set to 255, with no extra, name, or comment
703
fields. The gzip header is returned to the default state by deflateReset().
705
deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
706
stream state was inconsistent.
710
ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
713
This is another version of inflateInit with an extra parameter. The
714
fields next_in, avail_in, zalloc, zfree and opaque must be initialized
715
before by the caller.
717
The windowBits parameter is the base two logarithm of the maximum window
718
size (the size of the history buffer). It should be in the range 8..15 for
719
this version of the library. The default value is 15 if inflateInit is used
720
instead. windowBits must be greater than or equal to the windowBits value
721
provided to deflateInit2() while compressing, or it must be equal to 15 if
722
deflateInit2() was not used. If a compressed stream with a larger window
723
size is given as input, inflate() will return with the error code
724
Z_DATA_ERROR instead of trying to allocate a larger window.
726
windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
727
determines the window size. inflate() will then process raw deflate data,
728
not looking for a zlib or gzip header, not generating a check value, and not
729
looking for any check values for comparison at the end of the stream. This
730
is for use with other formats that use the deflate compressed data format
731
such as zip. Those formats provide their own check values. If a custom
732
format is developed using the raw deflate format for compressed data, it is
733
recommended that a check value such as an adler32 or a crc32 be applied to
734
the uncompressed data as is done in the zlib, gzip, and zip formats. For
735
most applications, the zlib format should be used as is. Note that comments
736
above on the use in deflateInit2() applies to the magnitude of windowBits.
738
windowBits can also be greater than 15 for optional gzip decoding. Add
739
32 to windowBits to enable zlib and gzip decoding with automatic header
740
detection, or add 16 to decode only the gzip format (the zlib format will
741
return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is
742
a crc32 instead of an adler32.
744
inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
745
memory, Z_STREAM_ERROR if a parameter is invalid (such as a null strm). msg
746
is set to null if there is no error message. inflateInit2 does not perform
747
any decompression apart from reading the zlib header if present: this will
748
be done by inflate(). (So next_in and avail_in may be modified, but next_out
749
and avail_out are unchanged.)
752
ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
753
const Bytef *dictionary,
756
Initializes the decompression dictionary from the given uncompressed byte
757
sequence. This function must be called immediately after a call of inflate,
758
if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
759
can be determined from the adler32 value returned by that call of inflate.
760
The compressor and decompressor must use exactly the same dictionary (see
761
deflateSetDictionary). For raw inflate, this function can be called
762
immediately after inflateInit2() or inflateReset() and before any call of
763
inflate() to set the dictionary. The application must insure that the
764
dictionary that was used for compression is provided.
766
inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
767
parameter is invalid (such as NULL dictionary) or the stream state is
768
inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
769
expected one (incorrect adler32 value). inflateSetDictionary does not
770
perform any decompression: this will be done by subsequent calls of
774
ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
776
Skips invalid compressed data until a full flush point (see above the
777
description of deflate with Z_FULL_FLUSH) can be found, or until all
778
available input is skipped. No output is provided.
780
inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
781
if no more input was provided, Z_DATA_ERROR if no flush point has been found,
782
or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
783
case, the application may save the current current value of total_in which
784
indicates where valid compressed data was found. In the error case, the
785
application may repeatedly call inflateSync, providing more input each time,
786
until success or end of the input data.
789
ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
792
Sets the destination stream as a complete copy of the source stream.
794
This function can be useful when randomly accessing a large stream. The
795
first pass through the stream can periodically record the inflate state,
796
allowing restarting inflate at those points when randomly accessing the
799
inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
800
enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
801
(such as zalloc being NULL). msg is left unchanged in both source and
805
ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
807
This function is equivalent to inflateEnd followed by inflateInit,
808
but does not free and reallocate all the internal decompression state.
809
The stream will keep attributes that may have been set by inflateInit2.
811
inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
812
stream state was inconsistent (such as zalloc or state being NULL).
815
ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
819
This function inserts bits in the inflate input stream. The intent is
820
that this function is used to start inflating at a bit position in the
821
middle of a byte. The provided bits will be used before any bytes are used
822
from next_in. This function should only be used with raw inflate, and
823
should be used before the first inflate() call after inflateInit2() or
824
inflateReset(). bits must be less than or equal to 16, and that many of the
825
least significant bits of value will be inserted in the input.
827
inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
828
stream state was inconsistent.
831
ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
834
inflateGetHeader() requests that gzip header information be stored in the
835
provided gz_header structure. inflateGetHeader() may be called after
836
inflateInit2() or inflateReset(), and before the first call of inflate().
837
As inflate() processes the gzip stream, head->done is zero until the header
838
is completed, at which time head->done is set to one. If a zlib stream is
839
being decoded, then head->done is set to -1 to indicate that there will be
840
no gzip header information forthcoming. Note that Z_BLOCK can be used to
841
force inflate() to return immediately after header processing is complete
842
and before any actual data is decompressed.
844
The text, time, xflags, and os fields are filled in with the gzip header
845
contents. hcrc is set to true if there is a header CRC. (The header CRC
846
was valid if done is set to one.) If extra is not Z_NULL, then extra_max
847
contains the maximum number of bytes to write to extra. Once done is true,
848
extra_len contains the actual extra field length, and extra contains the
849
extra field, or that field truncated if extra_max is less than extra_len.
850
If name is not Z_NULL, then up to name_max characters are written there,
851
terminated with a zero unless the length is greater than name_max. If
852
comment is not Z_NULL, then up to comm_max characters are written there,
853
terminated with a zero unless the length is greater than comm_max. When
854
any of extra, name, or comment are not Z_NULL and the respective field is
855
not present in the header, then that field is set to Z_NULL to signal its
856
absence. This allows the use of deflateSetHeader() with the returned
857
structure to duplicate the header. However if those fields are set to
858
allocated memory, then the application will need to save those pointers
859
elsewhere so that they can be eventually freed.
861
If inflateGetHeader is not used, then the header information is simply
862
discarded. The header is always checked for validity, including the header
863
CRC if present. inflateReset() will reset the process to discard the header
864
information. The application would need to call inflateGetHeader() again to
865
retrieve the header from the next gzip stream.
867
inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
868
stream state was inconsistent.
872
ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
873
unsigned char FAR *window));
875
Initialize the internal stream state for decompression using inflateBack()
876
calls. The fields zalloc, zfree and opaque in strm must be initialized
877
before the call. If zalloc and zfree are Z_NULL, then the default library-
878
derived memory allocation routines are used. windowBits is the base two
879
logarithm of the window size, in the range 8..15. window is a caller
880
supplied buffer of that size. Except for special applications where it is
881
assured that deflate was used with small window sizes, windowBits must be 15
882
and a 32K byte window must be supplied to be able to decompress general
885
See inflateBack() for the usage of these routines.
887
inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
888
the paramaters are invalid, Z_MEM_ERROR if the internal state could not
889
be allocated, or Z_VERSION_ERROR if the version of the library does not
890
match the version of the header file.
893
typedef unsigned (*in_func) OF((void FAR *, unsigned const char FAR * FAR *));
894
typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
896
ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
897
in_func in, void FAR *in_desc,
898
out_func out, void FAR *out_desc));
900
inflateBack() does a raw inflate with a single call using a call-back
901
interface for input and output. This is more efficient than inflate() for
902
file i/o applications in that it avoids copying between the output and the
903
sliding window by simply making the window itself the output buffer. This
904
function trusts the application to not change the output buffer passed by
905
the output function, at least until inflateBack() returns.
907
inflateBackInit() must be called first to allocate the internal state
908
and to initialize the state with the user-provided window buffer.
909
inflateBack() may then be used multiple times to inflate a complete, raw
910
deflate stream with each call. inflateBackEnd() is then called to free
913
A raw deflate stream is one with no zlib or gzip header or trailer.
914
This routine would normally be used in a utility that reads zip or gzip
915
files and writes out uncompressed files. The utility would decode the
916
header and process the trailer on its own, hence this routine expects
917
only the raw deflate stream to decompress. This is different from the
918
normal behavior of inflate(), which expects either a zlib or gzip header and
919
trailer around the deflate stream.
921
inflateBack() uses two subroutines supplied by the caller that are then
922
called by inflateBack() for input and output. inflateBack() calls those
923
routines until it reads a complete deflate stream and writes out all of the
924
uncompressed data, or until it encounters an error. The function's
925
parameters and return types are defined above in the in_func and out_func
926
typedefs. inflateBack() will call in(in_desc, &buf) which should return the
927
number of bytes of provided input, and a pointer to that input in buf. If
928
there is no input available, in() must return zero--buf is ignored in that
929
case--and inflateBack() will return a buffer error. inflateBack() will call
930
out(out_desc, buf, len) to write the uncompressed data buf[0..len-1]. out()
931
should return zero on success, or non-zero on failure. If out() returns
932
non-zero, inflateBack() will return with an error. Neither in() nor out()
933
are permitted to change the contents of the window provided to
934
inflateBackInit(), which is also the buffer that out() uses to write from.
935
The length written by out() will be at most the window size. Any non-zero
936
amount of input may be provided by in().
938
For convenience, inflateBack() can be provided input on the first call by
939
setting strm->next_in and strm->avail_in. If that input is exhausted, then
940
in() will be called. Therefore strm->next_in must be initialized before
941
calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
942
immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
943
must also be initialized, and then if strm->avail_in is not zero, input will
944
initially be taken from strm->next_in[0 .. strm->avail_in - 1].
946
The in_desc and out_desc parameters of inflateBack() is passed as the
947
first parameter of in() and out() respectively when they are called. These
948
descriptors can be optionally used to pass any information that the caller-
949
supplied in() and out() functions need to do their job.
951
On return, inflateBack() will set strm->next_in and strm->avail_in to
952
pass back any unused input that was provided by the last in() call. The
953
return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
954
if in() or out() returned an error, Z_DATA_ERROR if there was a format
955
error in the deflate stream (in which case strm->msg is set to indicate the
956
nature of the error), or Z_STREAM_ERROR if the stream was not properly
957
initialized. In the case of Z_BUF_ERROR, an input or output error can be
958
distinguished using strm->next_in which will be Z_NULL only if in() returned
959
an error. If strm->next is not Z_NULL, then the Z_BUF_ERROR was due to
960
out() returning non-zero. (in() will always be called before out(), so
961
strm->next_in is assured to be defined if out() returns non-zero.) Note
962
that inflateBack() cannot return Z_OK.
965
ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
967
All memory allocated by inflateBackInit() is freed.
969
inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
970
state was inconsistent.
973
ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
974
/* Return flags indicating compile-time options.
976
Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
979
5.4: size of voidpf (pointer)
982
Compiler, assembler, and debug options:
984
9: ASMV or ASMINF -- use ASM code
985
10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
988
One-time table building (smaller code, but not thread-safe if true):
989
12: BUILDFIXED -- build static block decoding tables when needed
990
13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
993
Library content (indicates missing functionality):
994
16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
995
deflate code when not needed)
996
17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
997
and decode gzip streams (to avoid linking crc code)
1000
Operation variations (changes in library functionality):
1001
20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
1002
21: FASTEST -- deflate algorithm with only one, lowest compression level
1005
The sprintf variant used by gzprintf (zero is best):
1006
24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1007
25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1008
26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1015
/* utility functions */
1018
The following utility functions are implemented on top of the
1019
basic stream-oriented functions. To simplify the interface, some
1020
default options are assumed (compression level and memory usage,
1021
standard memory allocation functions). The source code of these
1022
utility functions can easily be modified if you need special options.
1025
ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
1026
const Bytef *source, uLong sourceLen));
1028
Compresses the source buffer into the destination buffer. sourceLen is
1029
the byte length of the source buffer. Upon entry, destLen is the total
1030
size of the destination buffer, which must be at least the value returned
1031
by compressBound(sourceLen). Upon exit, destLen is the actual size of the
1033
This function can be used to compress a whole file at once if the
1034
input file is mmap'ed.
1035
compress returns Z_OK if success, Z_MEM_ERROR if there was not
1036
enough memory, Z_BUF_ERROR if there was not enough room in the output
1040
ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
1041
const Bytef *source, uLong sourceLen,
1044
Compresses the source buffer into the destination buffer. The level
1045
parameter has the same meaning as in deflateInit. sourceLen is the byte
1046
length of the source buffer. Upon entry, destLen is the total size of the
1047
destination buffer, which must be at least the value returned by
1048
compressBound(sourceLen). Upon exit, destLen is the actual size of the
1051
compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1052
memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1053
Z_STREAM_ERROR if the level parameter is invalid.
1056
ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
1058
compressBound() returns an upper bound on the compressed size after
1059
compress() or compress2() on sourceLen bytes. It would be used before
1060
a compress() or compress2() call to allocate the destination buffer.
1063
ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
1064
const Bytef *source, uLong sourceLen));
1066
Decompresses the source buffer into the destination buffer. sourceLen is
1067
the byte length of the source buffer. Upon entry, destLen is the total
1068
size of the destination buffer, which must be large enough to hold the
1069
entire uncompressed data. (The size of the uncompressed data must have
1070
been saved previously by the compressor and transmitted to the decompressor
1071
by some mechanism outside the scope of this compression library.)
1072
Upon exit, destLen is the actual size of the compressed buffer.
1073
This function can be used to decompress a whole file at once if the
1074
input file is mmap'ed.
1076
uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1077
enough memory, Z_BUF_ERROR if there was not enough room in the output
1078
buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.
1082
typedef voidp gzFile;
1084
ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
1086
Opens a gzip (.gz) file for reading or writing. The mode parameter
1087
is as in fopen ("rb" or "wb") but can also include a compression level
1088
("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
1089
Huffman only compression as in "wb1h", or 'R' for run-length encoding
1090
as in "wb1R". (See the description of deflateInit2 for more information
1091
about the strategy parameter.)
1093
gzopen can be used to read a file which is not in gzip format; in this
1094
case gzread will directly read from the file without decompression.
1096
gzopen returns NULL if the file could not be opened or if there was
1097
insufficient memory to allocate the (de)compression state; errno
1098
can be checked to distinguish the two cases (if errno is zero, the
1099
zlib error is Z_MEM_ERROR). */
1101
ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
1103
gzdopen() associates a gzFile with the file descriptor fd. File
1104
descriptors are obtained from calls like open, dup, creat, pipe or
1105
fileno (in the file has been previously opened with fopen).
1106
The mode parameter is as in gzopen.
1107
The next call of gzclose on the returned gzFile will also close the
1108
file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
1109
descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
1110
gzdopen returns NULL if there was insufficient memory to allocate
1111
the (de)compression state.
1114
ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
1116
Dynamically update the compression level or strategy. See the description
1117
of deflateInit2 for the meaning of these parameters.
1118
gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
1122
ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
1124
Reads the given number of uncompressed bytes from the compressed file.
1125
If the input file was not in gzip format, gzread copies the given number
1126
of bytes into the buffer.
1127
gzread returns the number of uncompressed bytes actually read (0 for
1128
end of file, -1 for error). */
1130
ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
1131
voidpc buf, unsigned len));
1133
Writes the given number of uncompressed bytes into the compressed file.
1134
gzwrite returns the number of uncompressed bytes actually written
1135
(0 in case of error).
1138
ZEXTERN int ZEXPORTVA gzprintf OF((gzFile file, const char *format, ...))
1139
_Z_PRINTF_ATTRIBUTE(2, 3);
1141
Converts, formats, and writes the args to the compressed file under
1142
control of the format string, as in fprintf. gzprintf returns the number of
1143
uncompressed bytes actually written (0 in case of error). The number of
1144
uncompressed bytes written is limited to 4095. The caller should assure that
1145
this limit is not exceeded. If it is exceeded, then gzprintf() will return
1146
return an error (0) with nothing written. In this case, there may also be a
1147
buffer overflow with unpredictable consequences, which is possible only if
1148
zlib was compiled with the insecure functions sprintf() or vsprintf()
1149
because the secure snprintf() or vsnprintf() functions were not available.
1152
ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
1154
Writes the given null-terminated string to the compressed file, excluding
1155
the terminating null character.
1156
gzputs returns the number of characters written, or -1 in case of error.
1159
ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
1161
Reads bytes from the compressed file until len-1 characters are read, or
1162
a newline character is read and transferred to buf, or an end-of-file
1163
condition is encountered. The string is then terminated with a null
1165
gzgets returns buf, or Z_NULL in case of error.
1168
ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
1170
Writes c, converted to an unsigned char, into the compressed file.
1171
gzputc returns the value that was written, or -1 in case of error.
1174
ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
1176
Reads one byte from the compressed file. gzgetc returns this byte
1177
or -1 in case of end of file or error.
1180
ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
1182
Push one character back onto the stream to be read again later.
1183
Only one character of push-back is allowed. gzungetc() returns the
1184
character pushed, or -1 on failure. gzungetc() will fail if a
1185
character has been pushed but not read yet, or if c is -1. The pushed
1186
character will be discarded if the stream is repositioned with gzseek()
1190
ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
1192
Flushes all pending output into the compressed file. The parameter
1193
flush is as in the deflate() function. The return value is the zlib
1194
error number (see function gzerror below). gzflush returns Z_OK if
1195
the flush parameter is Z_FINISH and all output could be flushed.
1196
gzflush should be called only when strictly necessary because it can
1197
degrade compression.
1200
ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
1201
z_off_t offset, int whence));
1203
Sets the starting position for the next gzread or gzwrite on the
1204
given compressed file. The offset represents a number of bytes in the
1205
uncompressed data stream. The whence parameter is defined as in lseek(2);
1206
the value SEEK_END is not supported.
1207
If the file is opened for reading, this function is emulated but can be
1208
extremely slow. If the file is opened for writing, only forward seeks are
1209
supported; gzseek then compresses a sequence of zeroes up to the new
1212
gzseek returns the resulting offset location as measured in bytes from
1213
the beginning of the uncompressed stream, or -1 in case of error, in
1214
particular if the file is opened for writing and the new starting position
1215
would be before the current position.
1218
ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
1220
Rewinds the given file. This function is supported only for reading.
1222
gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
1225
ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
1227
Returns the starting position for the next gzread or gzwrite on the
1228
given compressed file. This position represents a number of bytes in the
1229
uncompressed data stream.
1231
gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1234
ZEXTERN int ZEXPORT gzeof OF((gzFile file));
1236
Returns 1 when EOF has previously been detected reading the given
1237
input stream, otherwise zero.
1240
ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
1242
Returns 1 if file is being read directly without decompression, otherwise
1246
ZEXTERN int ZEXPORT gzclose OF((gzFile file));
1248
Flushes all pending output if necessary, closes the compressed file
1249
and deallocates all the (de)compression state. The return value is the zlib
1250
error number (see function gzerror below).
1253
ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
1255
Returns the error message for the last error which occurred on the
1256
given compressed file. errnum is set to zlib error number. If an
1257
error occurred in the file system and not in the compression library,
1258
errnum is set to Z_ERRNO and the application may consult errno
1259
to get the exact error code.
1262
ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
1264
Clears the error and end-of-file flags for file. This is analogous to the
1265
clearerr() function in stdio. This is useful for continuing to read a gzip
1266
file that is being written concurrently.
1269
/* checksum functions */
1272
These functions are not related to compression but are exported
1273
anyway because they might be useful in applications using the
1274
compression library.
1277
ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
1279
Update a running Adler-32 checksum with the bytes buf[0..len-1] and
1280
return the updated checksum. If buf is NULL, this function returns
1281
the required initial value for the checksum.
1282
An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
1283
much faster. Usage example:
1285
uLong adler = adler32(0L, Z_NULL, 0);
1287
while (read_buffer(buffer, length) != EOF) {
1288
adler = adler32(adler, buffer, length);
1290
if (adler != original_adler) error();
1293
ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
1296
Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
1297
and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1298
each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
1299
seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.
1302
ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
1304
Update a running CRC-32 with the bytes buf[0..len-1] and return the
1305
updated CRC-32. If buf is NULL, this function returns the required initial
1306
value for the for the crc. Pre- and post-conditioning (one's complement) is
1307
performed within this function so it shouldn't be done by the application.
1310
uLong crc = crc32(0L, Z_NULL, 0);
1312
while (read_buffer(buffer, length) != EOF) {
1313
crc = crc32(crc, buffer, length);
1315
if (crc != original_crc) error();
1318
ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
1321
Combine two CRC-32 check values into one. For two sequences of bytes,
1322
seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1323
calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
1324
check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1329
/* various hacks, don't look :) */
1331
/* deflateInit and inflateInit are macros to allow checking the zlib version
1332
* and the compiler's view of z_stream:
1334
ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
1335
const char *version, int stream_size));
1336
ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
1337
const char *version, int stream_size));
1338
ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
1339
int windowBits, int memLevel,
1340
int strategy, const char *version,
1342
ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
1343
const char *version, int stream_size));
1344
ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
1345
unsigned char FAR *window,
1346
const char *version,
1348
#define deflateInit(strm, level) \
1349
deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream))
1350
#define inflateInit(strm) \
1351
inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream))
1352
#define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
1353
deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
1354
(strategy), ZLIB_VERSION, sizeof(z_stream))
1355
#define inflateInit2(strm, windowBits) \
1356
inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
1357
#define inflateBackInit(strm, windowBits, window) \
1358
inflateBackInit_((strm), (windowBits), (window), \
1359
ZLIB_VERSION, sizeof(z_stream))
1362
#if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
1363
struct internal_state {int dummy;}; /* hack for buggy compilers */
1366
ZEXTERN const char * ZEXPORT zError OF((int));
1367
ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp z));
1368
ZEXTERN const uLongf * ZEXPORT get_crc_table OF((void));
added
removed
lib/zlib/zlib.h
