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1614 lines
78 KiB
1614 lines
78 KiB
5 years ago
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/* zlib.h -- interface of the 'zlib' general purpose compression library
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version 1.2.5, April 19th, 2010
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Copyright (C) 1995-2010 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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*/
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#ifndef ZLIB_H
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#define ZLIB_H
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#include "zconf.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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#define ZLIB_VERSION "1.2.5"
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#define ZLIB_VERNUM 0x1250
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#define ZLIB_VER_MAJOR 1
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#define ZLIB_VER_MINOR 2
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#define ZLIB_VER_REVISION 5
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#define ZLIB_VER_SUBREVISION 0
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/*
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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 data.
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This version of the library supports only one compression method (deflation)
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but other algorithms will be added later and will have the same stream
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interface.
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Compression can be done in a single step if the buffers are large enough,
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or can be done by repeated calls of the compression function. In the latter
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case, the 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 crash
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even in case of corrupted input.
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*/
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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: 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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} z_stream;
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typedef z_stream FAR *z_streamp;
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/*
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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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*/
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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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} gz_header;
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typedef gz_header FAR *gz_headerp;
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/*
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The application must update next_in and avail_in when avail_in has dropped
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to zero. It must update next_out and avail_out when avail_out has dropped
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to zero. The application must initialize zalloc, zfree and opaque before
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calling the init function. All other fields are set by the compression
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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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opaque value.
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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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thread safe.
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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 if
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the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS, pointers
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returned by zalloc for objects of exactly 65536 bytes *must* have their
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offset normalized to zero. The default allocation function provided by this
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library ensures this (see zutil.c). To reduce memory requirements and avoid
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any allocation of 64K objects, at the expense of compression ratio, compile
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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 progress
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reports. After compression, total_in holds the total size of the
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uncompressed data and may be saved for use in the decompressor (particularly
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if the decompressor wants to decompress everything in a single step).
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*/
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/* constants */
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#define Z_NO_FLUSH 0
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#define Z_PARTIAL_FLUSH 1
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#define Z_SYNC_FLUSH 2
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#define Z_FULL_FLUSH 3
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#define Z_FINISH 4
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#define Z_BLOCK 5
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#define Z_TREES 6
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/* Allowed flush values; see deflate() and inflate() below for details */
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#define Z_OK 0
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#define Z_STREAM_END 1
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#define Z_NEED_DICT 2
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#define Z_ERRNO (-1)
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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 values
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* are errors, positive values are used for special but normal events.
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*/
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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_FILTERED 1
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#define Z_HUFFMAN_ONLY 2
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#define Z_RLE 3
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#define Z_FIXED 4
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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_BINARY 0
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#define Z_TEXT 1
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#define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
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#define Z_UNKNOWN 2
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/* Possible values of the data_type field (though see inflate()) */
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#define Z_DEFLATED 8
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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 not
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compatible with the zlib.h header file used by the application. This check
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is automatically made by deflateInit and inflateInit.
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*/
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/*
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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. If
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zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
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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 all
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(the input data is simply copied a block at a time). Z_DEFAULT_COMPRESSION
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requests a default compromise between speed and compression (currently
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equivalent to level 6).
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deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
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memory, Z_STREAM_ERROR if level is not a valid compression level, or
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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). msg is set to null
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if there is no error message. deflateInit does not perform any compression:
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this will be done by deflate().
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*/
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ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
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/*
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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
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some output latency (reading input without producing any output) except when
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forced to flush.
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The detailed semantics are as follows. deflate performs one or both of the
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following actions:
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- Compress more input starting at next_in and update next_in and avail_in
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accordingly. If not all input can be processed (because there is not
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enough room in the output buffer), next_in and avail_in are updated and
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processing will resume at this point for the next call of deflate().
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- Provide more output starting at next_out and update next_out and avail_out
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accordingly. This action is forced if the parameter flush is non zero.
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Forcing flush frequently degrades the compression ratio, so this parameter
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should be set only when necessary (in interactive applications). Some
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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 more
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output, and updating avail_in or avail_out accordingly; avail_out should
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never be zero before the call. The application can consume the compressed
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output when it wants, for example when the output buffer is full (avail_out
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== 0), or after each call of deflate(). If deflate returns Z_OK and with
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zero avail_out, it must be called again after making room in the output
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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 accumulate 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
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particular avail_in is zero after the call if enough output space has been
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provided before the call.) Flushing may degrade compression for some
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compression algorithms and so it should be used only when necessary. This
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completes the current deflate block and follows it with an empty stored block
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that is three bits plus filler bits to the next byte, followed by four bytes
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(00 00 ff ff).
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If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
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output buffer, but the output is not aligned to a byte boundary. All of the
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input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
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This completes the current deflate block and follows it with an empty fixed
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codes block that is 10 bits long. This assures that enough bytes are output
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in order for the decompressor to finish the block before the empty fixed code
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block.
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If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
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for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
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seven bits of the current block are held to be written as the next byte after
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the next deflate block is completed. In this case, the decompressor may not
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be provided enough bits at this point in order to complete decompression of
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the data provided so far to the compressor. It may need to wait for the next
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block to be emitted. This is for advanced applications that need to control
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the emission of deflate blocks.
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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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compression.
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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 was
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||
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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 stream
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are deflateReset or deflateEnd.
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||
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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 the
|
||
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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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||
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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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||
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deflate() may update strm->data_type if it can make a good guess about
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||
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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 the
|
||
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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
|
||
|
Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
|
||
|
if next_in or next_out was Z_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.
|
||
|
*/
|
||
|
|
||
|
|
||
|
ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
|
||
|
/*
|
||
|
All dynamically allocated data structures for this stream are freed.
|
||
|
This function discards any unprocessed input and does not flush any pending
|
||
|
output.
|
||
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||
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deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
|
||
|
stream state was inconsistent, Z_DATA_ERROR if the stream was freed
|
||
|
prematurely (some input or output was discarded). In the error case, msg
|
||
|
may be set but then points to a static string (which must not be
|
||
|
deallocated).
|
||
|
*/
|
||
|
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||
|
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||
|
/*
|
||
|
ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
|
||
|
|
||
|
Initializes the internal stream state for decompression. The fields
|
||
|
next_in, avail_in, zalloc, zfree and opaque must be initialized before by
|
||
|
the caller. If next_in is not Z_NULL and avail_in is large enough (the
|
||
|
exact value depends on the compression method), inflateInit determines the
|
||
|
compression method from the zlib header and allocates all data structures
|
||
|
accordingly; otherwise the allocation will be deferred to the first call of
|
||
|
inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to
|
||
|
use default allocation functions.
|
||
|
|
||
|
inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
|
||
|
memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
|
||
|
version assumed by the caller, or Z_STREAM_ERROR if the parameters are
|
||
|
invalid, such as a null pointer to the structure. msg is set to null if
|
||
|
there is no error message. inflateInit does not perform any decompression
|
||
|
apart from possibly reading the zlib header if present: actual decompression
|
||
|
will be done by inflate(). (So next_in and avail_in may be modified, but
|
||
|
next_out and avail_out are unused and unchanged.) The current implementation
|
||
|
of inflateInit() does not process any header information -- that is deferred
|
||
|
until inflate() is called.
|
||
|
*/
|
||
|
|
||
|
|
||
|
ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
|
||
|
/*
|
||
|
inflate decompresses as much data as possible, and stops when the input
|
||
|
buffer becomes empty or the output buffer becomes full. It may introduce
|
||
|
some output latency (reading input without producing any output) except when
|
||
|
forced to flush.
|
||
|
|
||
|
The detailed semantics are as follows. inflate performs one or both of the
|
||
|
following actions:
|
||
|
|
||
|
- Decompress more input starting at next_in and update next_in and avail_in
|
||
|
accordingly. If not all input can be processed (because there is not
|
||
|
enough room in the output buffer), next_in is updated and processing will
|
||
|
resume at this point for the next call of inflate().
|
||
|
|
||
|
- Provide more output starting at next_out and update next_out and avail_out
|
||
|
accordingly. inflate() provides as much output as possible, until there is
|
||
|
no more input data or no more space in the output buffer (see below about
|
||
|
the flush parameter).
|
||
|
|
||
|
Before the call of inflate(), the application should ensure that at least
|
||
|
one of the actions is possible, by providing more input and/or consuming more
|
||
|
output, and updating the next_* and avail_* values accordingly. The
|
||
|
application can consume the uncompressed output when it wants, for example
|
||
|
when the output buffer is full (avail_out == 0), or after each call of
|
||
|
inflate(). If inflate returns Z_OK and with zero avail_out, it must be
|
||
|
called again after making room in the output buffer because there might be
|
||
|
more output pending.
|
||
|
|
||
|
The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
|
||
|
Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much
|
||
|
output as possible to the output buffer. Z_BLOCK requests that inflate()
|
||
|
stop if and when it gets to the next deflate block boundary. When decoding
|
||
|
the zlib or gzip format, this will cause inflate() to return immediately
|
||
|
after the header and before the first block. When doing a raw inflate,
|
||
|
inflate() will go ahead and process the first block, and will return when it
|
||
|
gets to the end of that block, or when it runs out of data.
|
||
|
|
||
|
The Z_BLOCK option assists in appending to or combining deflate streams.
|
||
|
Also to assist in this, on return inflate() will set strm->data_type to the
|
||
|
number of unused bits in the last byte taken from strm->next_in, plus 64 if
|
||
|
inflate() is currently decoding the last block in the deflate stream, plus
|
||
|
128 if inflate() returned immediately after decoding an end-of-block code or
|
||
|
decoding the complete header up to just before the first byte of the deflate
|
||
|
stream. The end-of-block will not be indicated until all of the uncompressed
|
||
|
data from that block has been written to strm->next_out. The number of
|
||
|
unused bits may in general be greater than seven, except when bit 7 of
|
||
|
data_type is set, in which case the number of unused bits will be less than
|
||
|
eight. data_type is set as noted here every time inflate() returns for all
|
||
|
flush options, and so can be used to determine the amount of currently
|
||
|
consumed input in bits.
|
||
|
|
||
|
The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
|
||
|
end of each deflate block header is reached, before any actual data in that
|
||
|
block is decoded. This allows the caller to determine the length of the
|
||
|
deflate block header for later use in random access within a deflate block.
|
||
|
256 is added to the value of strm->data_type when inflate() returns
|
||
|
immediately after reaching the end of the deflate block header.
|
||
|
|
||
|
inflate() should normally be called until it returns Z_STREAM_END or an
|
||
|
error. However if all decompression is to be performed in a single step (a
|
||
|
single call of inflate), the parameter flush should be set to Z_FINISH. In
|
||
|
this case all pending input is processed and all pending output is flushed;
|
||
|
avail_out must be large enough to hold all the uncompressed data. (The size
|
||
|
of the uncompressed data may have been saved by the compressor for this
|
||
|
purpose.) The next operation on this stream must be inflateEnd to deallocate
|
||
|
the decompression state. The use of Z_FINISH is never required, but can be
|
||
|
used to inform inflate that a faster approach may be used for the single
|
||
|
inflate() call.
|
||
|
|
||
|
In this implementation, inflate() always flushes as much output as
|
||
|
possible to the output buffer, and always uses the faster approach on the
|
||
|
first call. So the only effect of the flush parameter in this implementation
|
||
|
is on the return value of inflate(), as noted below, or when it returns early
|
||
|
because Z_BLOCK or Z_TREES is used.
|
||
|
|
||
|
If a preset dictionary is needed after this call (see inflateSetDictionary
|
||
|
below), inflate sets strm->adler to the adler32 checksum of the dictionary
|
||
|
chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
|
||
|
strm->adler to the adler32 checksum of all output produced so far (that is,
|
||
|
total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
|
||
|
below. At the end of the stream, inflate() checks that its computed adler32
|
||
|
checksum is equal to that saved by the compressor and returns Z_STREAM_END
|
||
|
only if the checksum is correct.
|
||
|
|
||
|
inflate() can decompress and check either zlib-wrapped or gzip-wrapped
|
||
|
deflate data. The header type is detected automatically, if requested when
|
||
|
initializing with inflateInit2(). Any information contained in the gzip
|
||
|
header is not retained, so applications that need that information should
|
||
|
instead use raw inflate, see inflateInit2() below, or inflateBack() and
|
||
|
perform their own processing of the gzip header and trailer.
|
||
|
|
||
|
inflate() returns Z_OK if some progress has been made (more input processed
|
||
|
or more output produced), Z_STREAM_END if the end of the compressed data has
|
||
|
been reached and all uncompressed output has been produced, Z_NEED_DICT if a
|
||
|
preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
|
||
|
corrupted (input stream not conforming to the zlib format or incorrect check
|
||
|
value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
|
||
|
next_in or next_out was Z_NULL), Z_MEM_ERROR if there was not enough memory,
|
||
|
Z_BUF_ERROR if no progress is possible or if there was not enough room in the
|
||
|
output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
|
||
|
inflate() can be called again with more input and more output space to
|
||
|
continue decompressing. If Z_DATA_ERROR is returned, the application may
|
||
|
then call inflateSync() to look for a good compression block if a partial
|
||
|
recovery of the data is desired.
|
||
|
*/
|
||
|
|
||
|
|
||
|
ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
|
||
|
/*
|
||
|
All dynamically allocated data structures for this stream are freed.
|
||
|
This function discards any unprocessed input and does not flush any pending
|
||
|
output.
|
||
|
|
||
|
inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
|
||
|
was inconsistent. In the error case, msg may be set but then points to a
|
||
|
static string (which must not be deallocated).
|
||
|
*/
|
||
|
|
||
|
|
||
|
/* Advanced functions */
|
||
|
|
||
|
/*
|
||
|
The following functions are needed only in some special applications.
|
||
|
*/
|
||
|
|
||
|
/*
|
||
|
ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
|
||
|
int level,
|
||
|
int method,
|
||
|
int windowBits,
|
||
|
int memLevel,
|
||
|
int strategy));
|
||
|
|
||
|
This is another version of deflateInit with more compression options. The
|
||
|
fields next_in, zalloc, zfree and opaque must be initialized before by the
|
||
|
caller.
|
||
|
|
||
|
The method parameter is the compression method. It must be Z_DEFLATED in
|
||
|
this version of the library.
|
||
|
|
||
|
The windowBits parameter is the base two logarithm of the window size
|
||
|
(the size of the history buffer). It should be in the range 8..15 for this
|
||
|
version of the library. Larger values of this parameter result in better
|
||
|
compression at the expense of memory usage. The default value is 15 if
|
||
|
deflateInit is used instead.
|
||
|
|
||
|
windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
|
||
|
determines the window size. deflate() will then generate raw deflate data
|
||
|
with no zlib header or trailer, and will not compute an adler32 check value.
|
||
|
|
||
|
windowBits can also be greater than 15 for optional gzip encoding. Add
|
||
|
16 to windowBits to write a simple gzip header and trailer around the
|
||
|
compressed data instead of a zlib wrapper. The gzip header will have no
|
||
|
file name, no extra data, no comment, no modification time (set to zero), no
|
||
|
header crc, and the operating system will be set to 255 (unknown). If a
|
||
|
gzip stream is being written, strm->adler is a crc32 instead of an adler32.
|
||
|
|
||
|
The memLevel parameter specifies how much memory should be allocated
|
||
|
for the internal compression state. memLevel=1 uses minimum memory but is
|
||
|
slow and reduces compression ratio; memLevel=9 uses maximum memory for
|
||
|
optimal speed. The default value is 8. See zconf.h for total memory usage
|
||
|
as a function of windowBits and memLevel.
|
||
|
|
||
|
The strategy parameter is used to tune the compression algorithm. Use the
|
||
|
value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
|
||
|
filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
|
||
|
string match), or Z_RLE to limit match distances to one (run-length
|
||
|
encoding). Filtered data consists mostly of small values with a somewhat
|
||
|
random distribution. In this case, the compression algorithm is tuned to
|
||
|
compress them better. The effect of Z_FILTERED is to force more Huffman
|
||
|
coding and less string matching; it is somewhat intermediate between
|
||
|
Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as
|
||
|
fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data. The
|
||
|
strategy parameter only affects the compression ratio but not the
|
||
|
correctness of the compressed output even if it is not set appropriately.
|
||
|
Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
|
||
|
decoder for special applications.
|
||
|
|
||
|
deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
|
||
|
memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
|
||
|
method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
|
||
|
incompatible with the version assumed by the caller (ZLIB_VERSION). msg is
|
||
|
set to null if there is no error message. deflateInit2 does not perform any
|
||
|
compression: this will be done by deflate().
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
|
||
|
const Bytef *dictionary,
|
||
|
uInt dictLength));
|
||
|
/*
|
||
|
Initializes the compression dictionary from the given byte sequence
|
||
|
without producing any compressed output. This function must be called
|
||
|
immediately after deflateInit, deflateInit2 or deflateReset, before any call
|
||
|
of deflate. The compressor and decompressor must use exactly the same
|
||
|
dictionary (see inflateSetDictionary).
|
||
|
|
||
|
The dictionary should consist of strings (byte sequences) that are likely
|
||
|
to be encountered later in the data to be compressed, with the most commonly
|
||
|
used strings preferably put towards the end of the dictionary. Using a
|
||
|
dictionary is most useful when the data to be compressed is short and can be
|
||
|
predicted with good accuracy; the data can then be compressed better than
|
||
|
with the default empty dictionary.
|
||
|
|
||
|
Depending on the size of the compression data structures selected by
|
||
|
deflateInit or deflateInit2, a part of the dictionary may in effect be
|
||
|
discarded, for example if the dictionary is larger than the window size
|
||
|
provided in deflateInit or deflateInit2. Thus the strings most likely to be
|
||
|
useful should be put at the end of the dictionary, not at the front. In
|
||
|
addition, the current implementation of deflate will use at most the window
|
||
|
size minus 262 bytes of the provided dictionary.
|
||
|
|
||
|
Upon return of this function, strm->adler is set to the adler32 value
|
||
|
of the dictionary; the decompressor may later use this value to determine
|
||
|
which dictionary has been used by the compressor. (The adler32 value
|
||
|
applies to the whole dictionary even if only a subset of the dictionary is
|
||
|
actually used by the compressor.) If a raw deflate was requested, then the
|
||
|
adler32 value is not computed and strm->adler is not set.
|
||
|
|
||
|
deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
|
||
|
parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
|
||
|
inconsistent (for example if deflate has already been called for this stream
|
||
|
or if the compression method is bsort). deflateSetDictionary does not
|
||
|
perform any compression: this will be done by deflate().
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
|
||
|
z_streamp source));
|
||
|
/*
|
||
|
Sets the destination stream as a complete copy of the source stream.
|
||
|
|
||
|
This function can be useful when several compression strategies will be
|
||
|
tried, for example when there are several ways of pre-processing the input
|
||
|
data with a filter. The streams that will be discarded should then be freed
|
||
|
by calling deflateEnd. Note that deflateCopy duplicates the internal
|
||
|
compression state which can be quite large, so this strategy is slow and can
|
||
|
consume lots of memory.
|
||
|
|
||
|
deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
|
||
|
enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
|
||
|
(such as zalloc being Z_NULL). msg is left unchanged in both source and
|
||
|
destination.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
|
||
|
/*
|
||
|
This function is equivalent to deflateEnd followed by deflateInit,
|
||
|
but does not free and reallocate all the internal compression state. The
|
||
|
stream will keep the same compression level and any other attributes that
|
||
|
may have been set by deflateInit2.
|
||
|
|
||
|
deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
|
||
|
stream state was inconsistent (such as zalloc or state being Z_NULL).
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
|
||
|
int level,
|
||
|
int strategy));
|
||
|
/*
|
||
|
Dynamically update the compression level and compression strategy. The
|
||
|
interpretation of level and strategy is as in deflateInit2. This can be
|
||
|
used to switch between compression and straight copy of the input data, or
|
||
|
to switch to a different kind of input data requiring a different strategy.
|
||
|
If the compression level is changed, the input available so far is
|
||
|
compressed with the old level (and may be flushed); the new level will take
|
||
|
effect only at the next call of deflate().
|
||
|
|
||
|
Before the call of deflateParams, the stream state must be set as for
|
||
|
a call of deflate(), since the currently available input may have to be
|
||
|
compressed and flushed. In particular, strm->avail_out must be non-zero.
|
||
|
|
||
|
deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
|
||
|
stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR if
|
||
|
strm->avail_out was zero.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
|
||
|
int good_length,
|
||
|
int max_lazy,
|
||
|
int nice_length,
|
||
|
int max_chain));
|
||
|
/*
|
||
|
Fine tune deflate's internal compression parameters. This should only be
|
||
|
used by someone who understands the algorithm used by zlib's deflate for
|
||
|
searching for the best matching string, and even then only by the most
|
||
|
fanatic optimizer trying to squeeze out the last compressed bit for their
|
||
|
specific input data. Read the deflate.c source code for the meaning of the
|
||
|
max_lazy, good_length, nice_length, and max_chain parameters.
|
||
|
|
||
|
deflateTune() can be called after deflateInit() or deflateInit2(), and
|
||
|
returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
|
||
|
uLong sourceLen));
|
||
|
/*
|
||
|
deflateBound() returns an upper bound on the compressed size after
|
||
|
deflation of sourceLen bytes. It must be called after deflateInit() or
|
||
|
deflateInit2(), and after deflateSetHeader(), if used. This would be used
|
||
|
to allocate an output buffer for deflation in a single pass, and so would be
|
||
|
called before deflate().
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
|
||
|
int bits,
|
||
|
int value));
|
||
|
/*
|
||
|
deflatePrime() inserts bits in the deflate output stream. The intent
|
||
|
is that this function is used to start off the deflate output with the bits
|
||
|
leftover from a previous deflate stream when appending to it. As such, this
|
||
|
function can only be used for raw deflate, and must be used before the first
|
||
|
deflate() call after a deflateInit2() or deflateReset(). bits must be less
|
||
|
than or equal to 16, and that many of the least significant bits of value
|
||
|
will be inserted in the output.
|
||
|
|
||
|
deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
|
||
|
stream state was inconsistent.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
|
||
|
gz_headerp head));
|
||
|
/*
|
||
|
deflateSetHeader() provides gzip header information for when a gzip
|
||
|
stream is requested by deflateInit2(). deflateSetHeader() may be called
|
||
|
after deflateInit2() or deflateReset() and before the first call of
|
||
|
deflate(). The text, time, os, extra field, name, and comment information
|
||
|
in the provided gz_header structure are written to the gzip header (xflag is
|
||
|
ignored -- the extra flags are set according to the compression level). The
|
||
|
caller must assure that, if not Z_NULL, name and comment are terminated with
|
||
|
a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
|
||
|
available there. If hcrc is true, a gzip header crc is included. Note that
|
||
|
the current versions of the command-line version of gzip (up through version
|
||
|
1.3.x) do not support header crc's, and will report that it is a "multi-part
|
||
|
gzip file" and give up.
|
||
|
|
||
|
If deflateSetHeader is not used, the default gzip header has text false,
|
||
|
the time set to zero, and os set to 255, with no extra, name, or comment
|
||
|
fields. The gzip header is returned to the default state by deflateReset().
|
||
|
|
||
|
deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
|
||
|
stream state was inconsistent.
|
||
|
*/
|
||
|
|
||
|
/*
|
||
|
ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
|
||
|
int windowBits));
|
||
|
|
||
|
This is another version of inflateInit with an extra parameter. The
|
||
|
fields next_in, avail_in, zalloc, zfree and opaque must be initialized
|
||
|
before by the caller.
|
||
|
|
||
|
The windowBits parameter is the base two logarithm of the maximum window
|
||
|
size (the size of the history buffer). It should be in the range 8..15 for
|
||
|
this version of the library. The default value is 15 if inflateInit is used
|
||
|
instead. windowBits must be greater than or equal to the windowBits value
|
||
|
provided to deflateInit2() while compressing, or it must be equal to 15 if
|
||
|
deflateInit2() was not used. If a compressed stream with a larger window
|
||
|
size is given as input, inflate() will return with the error code
|
||
|
Z_DATA_ERROR instead of trying to allocate a larger window.
|
||
|
|
||
|
windowBits can also be zero to request that inflate use the window size in
|
||
|
the zlib header of the compressed stream.
|
||
|
|
||
|
windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
|
||
|
determines the window size. inflate() will then process raw deflate data,
|
||
|
not looking for a zlib or gzip header, not generating a check value, and not
|
||
|
looking for any check values for comparison at the end of the stream. This
|
||
|
is for use with other formats that use the deflate compressed data format
|
||
|
such as zip. Those formats provide their own check values. If a custom
|
||
|
format is developed using the raw deflate format for compressed data, it is
|
||
|
recommended that a check value such as an adler32 or a crc32 be applied to
|
||
|
the uncompressed data as is done in the zlib, gzip, and zip formats. For
|
||
|
most applications, the zlib format should be used as is. Note that comments
|
||
|
above on the use in deflateInit2() applies to the magnitude of windowBits.
|
||
|
|
||
|
windowBits can also be greater than 15 for optional gzip decoding. Add
|
||
|
32 to windowBits to enable zlib and gzip decoding with automatic header
|
||
|
detection, or add 16 to decode only the gzip format (the zlib format will
|
||
|
return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is a
|
||
|
crc32 instead of an adler32.
|
||
|
|
||
|
inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
|
||
|
memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
|
||
|
version assumed by the caller, or Z_STREAM_ERROR if the parameters are
|
||
|
invalid, such as a null pointer to the structure. msg is set to null if
|
||
|
there is no error message. inflateInit2 does not perform any decompression
|
||
|
apart from possibly reading the zlib header if present: actual decompression
|
||
|
will be done by inflate(). (So next_in and avail_in may be modified, but
|
||
|
next_out and avail_out are unused and unchanged.) The current implementation
|
||
|
of inflateInit2() does not process any header information -- that is
|
||
|
deferred until inflate() is called.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
|
||
|
const Bytef *dictionary,
|
||
|
uInt dictLength));
|
||
|
/*
|
||
|
Initializes the decompression dictionary from the given uncompressed byte
|
||
|
sequence. This function must be called immediately after a call of inflate,
|
||
|
if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
|
||
|
can be determined from the adler32 value returned by that call of inflate.
|
||
|
The compressor and decompressor must use exactly the same dictionary (see
|
||
|
deflateSetDictionary). For raw inflate, this function can be called
|
||
|
immediately after inflateInit2() or inflateReset() and before any call of
|
||
|
inflate() to set the dictionary. The application must insure that the
|
||
|
dictionary that was used for compression is provided.
|
||
|
|
||
|
inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
|
||
|
parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
|
||
|
inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
|
||
|
expected one (incorrect adler32 value). inflateSetDictionary does not
|
||
|
perform any decompression: this will be done by subsequent calls of
|
||
|
inflate().
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
|
||
|
/*
|
||
|
Skips invalid compressed data until a full flush point (see above the
|
||
|
description of deflate with Z_FULL_FLUSH) can be found, or until all
|
||
|
available input is skipped. No output is provided.
|
||
|
|
||
|
inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
|
||
|
if no more input was provided, Z_DATA_ERROR if no flush point has been
|
||
|
found, or Z_STREAM_ERROR if the stream structure was inconsistent. In the
|
||
|
success case, the application may save the current current value of total_in
|
||
|
which indicates where valid compressed data was found. In the error case,
|
||
|
the application may repeatedly call inflateSync, providing more input each
|
||
|
time, until success or end of the input data.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
|
||
|
z_streamp source));
|
||
|
/*
|
||
|
Sets the destination stream as a complete copy of the source stream.
|
||
|
|
||
|
This function can be useful when randomly accessing a large stream. The
|
||
|
first pass through the stream can periodically record the inflate state,
|
||
|
allowing restarting inflate at those points when randomly accessing the
|
||
|
stream.
|
||
|
|
||
|
inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
|
||
|
enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
|
||
|
(such as zalloc being Z_NULL). msg is left unchanged in both source and
|
||
|
destination.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
|
||
|
/*
|
||
|
This function is equivalent to inflateEnd followed by inflateInit,
|
||
|
but does not free and reallocate all the internal decompression state. The
|
||
|
stream will keep attributes that may have been set by inflateInit2.
|
||
|
|
||
|
inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
|
||
|
stream state was inconsistent (such as zalloc or state being Z_NULL).
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
|
||
|
int windowBits));
|
||
|
/*
|
||
|
This function is the same as inflateReset, but it also permits changing
|
||
|
the wrap and window size requests. The windowBits parameter is interpreted
|
||
|
the same as it is for inflateInit2.
|
||
|
|
||
|
inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
|
||
|
stream state was inconsistent (such as zalloc or state being Z_NULL), or if
|
||
|
the windowBits parameter is invalid.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
|
||
|
int bits,
|
||
|
int value));
|
||
|
/*
|
||
|
This function inserts bits in the inflate input stream. The intent is
|
||
|
that this function is used to start inflating at a bit position in the
|
||
|
middle of a byte. The provided bits will be used before any bytes are used
|
||
|
from next_in. This function should only be used with raw inflate, and
|
||
|
should be used before the first inflate() call after inflateInit2() or
|
||
|
inflateReset(). bits must be less than or equal to 16, and that many of the
|
||
|
least significant bits of value will be inserted in the input.
|
||
|
|
||
|
If bits is negative, then the input stream bit buffer is emptied. Then
|
||
|
inflatePrime() can be called again to put bits in the buffer. This is used
|
||
|
to clear out bits leftover after feeding inflate a block description prior
|
||
|
to feeding inflate codes.
|
||
|
|
||
|
inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
|
||
|
stream state was inconsistent.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
|
||
|
/*
|
||
|
This function returns two values, one in the lower 16 bits of the return
|
||
|
value, and the other in the remaining upper bits, obtained by shifting the
|
||
|
return value down 16 bits. If the upper value is -1 and the lower value is
|
||
|
zero, then inflate() is currently decoding information outside of a block.
|
||
|
If the upper value is -1 and the lower value is non-zero, then inflate is in
|
||
|
the middle of a stored block, with the lower value equaling the number of
|
||
|
bytes from the input remaining to copy. If the upper value is not -1, then
|
||
|
it is the number of bits back from the current bit position in the input of
|
||
|
the code (literal or length/distance pair) currently being processed. In
|
||
|
that case the lower value is the number of bytes already emitted for that
|
||
|
code.
|
||
|
|
||
|
A code is being processed if inflate is waiting for more input to complete
|
||
|
decoding of the code, or if it has completed decoding but is waiting for
|
||
|
more output space to write the literal or match data.
|
||
|
|
||
|
inflateMark() is used to mark locations in the input data for random
|
||
|
access, which may be at bit positions, and to note those cases where the
|
||
|
output of a code may span boundaries of random access blocks. The current
|
||
|
location in the input stream can be determined from avail_in and data_type
|
||
|
as noted in the description for the Z_BLOCK flush parameter for inflate.
|
||
|
|
||
|
inflateMark returns the value noted above or -1 << 16 if the provided
|
||
|
source stream state was inconsistent.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
|
||
|
gz_headerp head));
|
||
|
/*
|
||
|
inflateGetHeader() requests that gzip header information be stored in the
|
||
|
provided gz_header structure. inflateGetHeader() may be called after
|
||
|
inflateInit2() or inflateReset(), and before the first call of inflate().
|
||
|
As inflate() processes the gzip stream, head->done is zero until the header
|
||
|
is completed, at which time head->done is set to one. If a zlib stream is
|
||
|
being decoded, then head->done is set to -1 to indicate that there will be
|
||
|
no gzip header information forthcoming. Note that Z_BLOCK or Z_TREES can be
|
||
|
used to force inflate() to return immediately after header processing is
|
||
|
complete and before any actual data is decompressed.
|
||
|
|
||
|
The text, time, xflags, and os fields are filled in with the gzip header
|
||
|
contents. hcrc is set to true if there is a header CRC. (The header CRC
|
||
|
was valid if done is set to one.) If extra is not Z_NULL, then extra_max
|
||
|
contains the maximum number of bytes to write to extra. Once done is true,
|
||
|
extra_len contains the actual extra field length, and extra contains the
|
||
|
extra field, or that field truncated if extra_max is less than extra_len.
|
||
|
If name is not Z_NULL, then up to name_max characters are written there,
|
||
|
terminated with a zero unless the length is greater than name_max. If
|
||
|
comment is not Z_NULL, then up to comm_max characters are written there,
|
||
|
terminated with a zero unless the length is greater than comm_max. When any
|
||
|
of extra, name, or comment are not Z_NULL and the respective field is not
|
||
|
present in the header, then that field is set to Z_NULL to signal its
|
||
|
absence. This allows the use of deflateSetHeader() with the returned
|
||
|
structure to duplicate the header. However if those fields are set to
|
||
|
allocated memory, then the application will need to save those pointers
|
||
|
elsewhere so that they can be eventually freed.
|
||
|
|
||
|
If inflateGetHeader is not used, then the header information is simply
|
||
|
discarded. The header is always checked for validity, including the header
|
||
|
CRC if present. inflateReset() will reset the process to discard the header
|
||
|
information. The application would need to call inflateGetHeader() again to
|
||
|
retrieve the header from the next gzip stream.
|
||
|
|
||
|
inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
|
||
|
stream state was inconsistent.
|
||
|
*/
|
||
|
|
||
|
/*
|
||
|
ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
|
||
|
unsigned char FAR *window));
|
||
|
|
||
|
Initialize the internal stream state for decompression using inflateBack()
|
||
|
calls. The fields zalloc, zfree and opaque in strm must be initialized
|
||
|
before the call. If zalloc and zfree are Z_NULL, then the default library-
|
||
|
derived memory allocation routines are used. windowBits is the base two
|
||
|
logarithm of the window size, in the range 8..15. window is a caller
|
||
|
supplied buffer of that size. Except for special applications where it is
|
||
|
assured that deflate was used with small window sizes, windowBits must be 15
|
||
|
and a 32K byte window must be supplied to be able to decompress general
|
||
|
deflate streams.
|
||
|
|
||
|
See inflateBack() for the usage of these routines.
|
||
|
|
||
|
inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
|
||
|
the paramaters are invalid, Z_MEM_ERROR if the internal state could not be
|
||
|
allocated, or Z_VERSION_ERROR if the version of the library does not match
|
||
|
the version of the header file.
|
||
|
*/
|
||
|
|
||
|
typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
|
||
|
typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
|
||
|
|
||
|
ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
|
||
|
in_func in, void FAR *in_desc,
|
||
|
out_func out, void FAR *out_desc));
|
||
|
/*
|
||
|
inflateBack() does a raw inflate with a single call using a call-back
|
||
|
interface for input and output. This is more efficient than inflate() for
|
||
|
file i/o applications in that it avoids copying between the output and the
|
||
|
sliding window by simply making the window itself the output buffer. This
|
||
|
function trusts the application to not change the output buffer passed by
|
||
|
the output function, at least until inflateBack() returns.
|
||
|
|
||
|
inflateBackInit() must be called first to allocate the internal state
|
||
|
and to initialize the state with the user-provided window buffer.
|
||
|
inflateBack() may then be used multiple times to inflate a complete, raw
|
||
|
deflate stream with each call. inflateBackEnd() is then called to free the
|
||
|
allocated state.
|
||
|
|
||
|
A raw deflate stream is one with no zlib or gzip header or trailer.
|
||
|
This routine would normally be used in a utility that reads zip or gzip
|
||
|
files and writes out uncompressed files. The utility would decode the
|
||
|
header and process the trailer on its own, hence this routine expects only
|
||
|
the raw deflate stream to decompress. This is different from the normal
|
||
|
behavior of inflate(), which expects either a zlib or gzip header and
|
||
|
trailer around the deflate stream.
|
||
|
|
||
|
inflateBack() uses two subroutines supplied by the caller that are then
|
||
|
called by inflateBack() for input and output. inflateBack() calls those
|
||
|
routines until it reads a complete deflate stream and writes out all of the
|
||
|
uncompressed data, or until it encounters an error. The function's
|
||
|
parameters and return types are defined above in the in_func and out_func
|
||
|
typedefs. inflateBack() will call in(in_desc, &buf) which should return the
|
||
|
number of bytes of provided input, and a pointer to that input in buf. If
|
||
|
there is no input available, in() must return zero--buf is ignored in that
|
||
|
case--and inflateBack() will return a buffer error. inflateBack() will call
|
||
|
out(out_desc, buf, len) to write the uncompressed data buf[0..len-1]. out()
|
||
|
should return zero on success, or non-zero on failure. If out() returns
|
||
|
non-zero, inflateBack() will return with an error. Neither in() nor out()
|
||
|
are permitted to change the contents of the window provided to
|
||
|
inflateBackInit(), which is also the buffer that out() uses to write from.
|
||
|
The length written by out() will be at most the window size. Any non-zero
|
||
|
amount of input may be provided by in().
|
||
|
|
||
|
For convenience, inflateBack() can be provided input on the first call by
|
||
|
setting strm->next_in and strm->avail_in. If that input is exhausted, then
|
||
|
in() will be called. Therefore strm->next_in must be initialized before
|
||
|
calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
|
||
|
immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
|
||
|
must also be initialized, and then if strm->avail_in is not zero, input will
|
||
|
initially be taken from strm->next_in[0 .. strm->avail_in - 1].
|
||
|
|
||
|
The in_desc and out_desc parameters of inflateBack() is passed as the
|
||
|
first parameter of in() and out() respectively when they are called. These
|
||
|
descriptors can be optionally used to pass any information that the caller-
|
||
|
supplied in() and out() functions need to do their job.
|
||
|
|
||
|
On return, inflateBack() will set strm->next_in and strm->avail_in to
|
||
|
pass back any unused input that was provided by the last in() call. The
|
||
|
return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
|
||
|
if in() or out() returned an error, Z_DATA_ERROR if there was a format error
|
||
|
in the deflate stream (in which case strm->msg is set to indicate the nature
|
||
|
of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
|
||
|
In the case of Z_BUF_ERROR, an input or output error can be distinguished
|
||
|
using strm->next_in which will be Z_NULL only if in() returned an error. If
|
||
|
strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
|
||
|
non-zero. (in() will always be called before out(), so strm->next_in is
|
||
|
assured to be defined if out() returns non-zero.) Note that inflateBack()
|
||
|
cannot return Z_OK.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
|
||
|
/*
|
||
|
All memory allocated by inflateBackInit() is freed.
|
||
|
|
||
|
inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
|
||
|
state was inconsistent.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
|
||
|
/* Return flags indicating compile-time options.
|
||
|
|
||
|
Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
|
||
|
1.0: size of uInt
|
||
|
3.2: size of uLong
|
||
|
5.4: size of voidpf (pointer)
|
||
|
7.6: size of z_off_t
|
||
|
|
||
|
Compiler, assembler, and debug options:
|
||
|
8: DEBUG
|
||
|
9: ASMV or ASMINF -- use ASM code
|
||
|
10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
|
||
|
11: 0 (reserved)
|
||
|
|
||
|
One-time table building (smaller code, but not thread-safe if true):
|
||
|
12: BUILDFIXED -- build static block decoding tables when needed
|
||
|
13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
|
||
|
14,15: 0 (reserved)
|
||
|
|
||
|
Library content (indicates missing functionality):
|
||
|
16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
|
||
|
deflate code when not needed)
|
||
|
17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
|
||
|
and decode gzip streams (to avoid linking crc code)
|
||
|
18-19: 0 (reserved)
|
||
|
|
||
|
Operation variations (changes in library functionality):
|
||
|
20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
|
||
|
21: FASTEST -- deflate algorithm with only one, lowest compression level
|
||
|
22,23: 0 (reserved)
|
||
|
|
||
|
The sprintf variant used by gzprintf (zero is best):
|
||
|
24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
|
||
|
25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
|
||
|
26: 0 = returns value, 1 = void -- 1 means inferred string length returned
|
||
|
|
||
|
Remainder:
|
||
|
27-31: 0 (reserved)
|
||
|
*/
|
||
|
|
||
|
|
||
|
/* utility functions */
|
||
|
|
||
|
/*
|
||
|
The following utility functions are implemented on top of the basic
|
||
|
stream-oriented functions. To simplify the interface, some default options
|
||
|
are assumed (compression level and memory usage, standard memory allocation
|
||
|
functions). The source code of these utility functions can be modified if
|
||
|
you need special options.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT compress OF((Bytef *dest, uLongf *destLen,
|
||
|
const Bytef *source, uLong sourceLen));
|
||
|
/*
|
||
|
Compresses the source buffer into the destination buffer. sourceLen is
|
||
|
the byte length of the source buffer. Upon entry, destLen is the total size
|
||
|
of the destination buffer, which must be at least the value returned by
|
||
|
compressBound(sourceLen). Upon exit, destLen is the actual size of the
|
||
|
compressed buffer.
|
||
|
|
||
|
compress returns Z_OK if success, Z_MEM_ERROR if there was not
|
||
|
enough memory, Z_BUF_ERROR if there was not enough room in the output
|
||
|
buffer.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT compress2 OF((Bytef *dest, uLongf *destLen,
|
||
|
const Bytef *source, uLong sourceLen,
|
||
|
int level));
|
||
|
/*
|
||
|
Compresses the source buffer into the destination buffer. The level
|
||
|
parameter has the same meaning as in deflateInit. sourceLen is the byte
|
||
|
length of the source buffer. Upon entry, destLen is the total size of the
|
||
|
destination buffer, which must be at least the value returned by
|
||
|
compressBound(sourceLen). Upon exit, destLen is the actual size of the
|
||
|
compressed buffer.
|
||
|
|
||
|
compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
|
||
|
memory, Z_BUF_ERROR if there was not enough room in the output buffer,
|
||
|
Z_STREAM_ERROR if the level parameter is invalid.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
|
||
|
/*
|
||
|
compressBound() returns an upper bound on the compressed size after
|
||
|
compress() or compress2() on sourceLen bytes. It would be used before a
|
||
|
compress() or compress2() call to allocate the destination buffer.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
|
||
|
const Bytef *source, uLong sourceLen));
|
||
|
/*
|
||
|
Decompresses the source buffer into the destination buffer. sourceLen is
|
||
|
the byte length of the source buffer. Upon entry, destLen is the total size
|
||
|
of the destination buffer, which must be large enough to hold the entire
|
||
|
uncompressed data. (The size of the uncompressed data must have been saved
|
||
|
previously by the compressor and transmitted to the decompressor by some
|
||
|
mechanism outside the scope of this compression library.) Upon exit, destLen
|
||
|
is the actual size of the uncompressed buffer.
|
||
|
|
||
|
uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
|
||
|
enough memory, Z_BUF_ERROR if there was not enough room in the output
|
||
|
buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.
|
||
|
*/
|
||
|
|
||
|
|
||
|
/* gzip file access functions */
|
||
|
|
||
|
/*
|
||
|
This library supports reading and writing files in gzip (.gz) format with
|
||
|
an interface similar to that of stdio, using the functions that start with
|
||
|
"gz". The gzip format is different from the zlib format. gzip is a gzip
|
||
|
wrapper, documented in RFC 1952, wrapped around a deflate stream.
|
||
|
*/
|
||
|
|
||
|
typedef voidp gzFile; /* opaque gzip file descriptor */
|
||
|
|
||
|
/*
|
||
|
ZEXTERN gzFile ZEXPORT gzopen OF((const char *path, const char *mode));
|
||
|
|
||
|
Opens a gzip (.gz) file for reading or writing. The mode parameter is as
|
||
|
in fopen ("rb" or "wb") but can also include a compression level ("wb9") or
|
||
|
a strategy: 'f' for filtered data as in "wb6f", 'h' for Huffman-only
|
||
|
compression as in "wb1h", 'R' for run-length encoding as in "wb1R", or 'F'
|
||
|
for fixed code compression as in "wb9F". (See the description of
|
||
|
deflateInit2 for more information about the strategy parameter.) Also "a"
|
||
|
can be used instead of "w" to request that the gzip stream that will be
|
||
|
written be appended to the file. "+" will result in an error, since reading
|
||
|
and writing to the same gzip file is not supported.
|
||
|
|
||
|
gzopen can be used to read a file which is not in gzip format; in this
|
||
|
case gzread will directly read from the file without decompression.
|
||
|
|
||
|
gzopen returns NULL if the file could not be opened, if there was
|
||
|
insufficient memory to allocate the gzFile state, or if an invalid mode was
|
||
|
specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
|
||
|
errno can be checked to determine if the reason gzopen failed was that the
|
||
|
file could not be opened.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN gzFile ZEXPORT gzdopen OF((int fd, const char *mode));
|
||
|
/*
|
||
|
gzdopen associates a gzFile with the file descriptor fd. File descriptors
|
||
|
are obtained from calls like open, dup, creat, pipe or fileno (if the file
|
||
|
has been previously opened with fopen). The mode parameter is as in gzopen.
|
||
|
|
||
|
The next call of gzclose on the returned gzFile will also close the file
|
||
|
descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
|
||
|
fd. If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
|
||
|
mode);. The duplicated descriptor should be saved to avoid a leak, since
|
||
|
gzdopen does not close fd if it fails.
|
||
|
|
||
|
gzdopen returns NULL if there was insufficient memory to allocate the
|
||
|
gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
|
||
|
provided, or '+' was provided), or if fd is -1. The file descriptor is not
|
||
|
used until the next gz* read, write, seek, or close operation, so gzdopen
|
||
|
will not detect if fd is invalid (unless fd is -1).
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));
|
||
|
/*
|
||
|
Set the internal buffer size used by this library's functions. The
|
||
|
default buffer size is 8192 bytes. This function must be called after
|
||
|
gzopen() or gzdopen(), and before any other calls that read or write the
|
||
|
file. The buffer memory allocation is always deferred to the first read or
|
||
|
write. Two buffers are allocated, either both of the specified size when
|
||
|
writing, or one of the specified size and the other twice that size when
|
||
|
reading. A larger buffer size of, for example, 64K or 128K bytes will
|
||
|
noticeably increase the speed of decompression (reading).
|
||
|
|
||
|
The new buffer size also affects the maximum length for gzprintf().
|
||
|
|
||
|
gzbuffer() returns 0 on success, or -1 on failure, such as being called
|
||
|
too late.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
|
||
|
/*
|
||
|
Dynamically update the compression level or strategy. See the description
|
||
|
of deflateInit2 for the meaning of these parameters.
|
||
|
|
||
|
gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
|
||
|
opened for writing.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len));
|
||
|
/*
|
||
|
Reads the given number of uncompressed bytes from the compressed file. If
|
||
|
the input file was not in gzip format, gzread copies the given number of
|
||
|
bytes into the buffer.
|
||
|
|
||
|
After reaching the end of a gzip stream in the input, gzread will continue
|
||
|
to read, looking for another gzip stream, or failing that, reading the rest
|
||
|
of the input file directly without decompression. The entire input file
|
||
|
will be read if gzread is called until it returns less than the requested
|
||
|
len.
|
||
|
|
||
|
gzread returns the number of uncompressed bytes actually read, less than
|
||
|
len for end of file, or -1 for error.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT gzwrite OF((gzFile file,
|
||
|
voidpc buf, unsigned len));
|
||
|
/*
|
||
|
Writes the given number of uncompressed bytes into the compressed file.
|
||
|
gzwrite returns the number of uncompressed bytes written or 0 in case of
|
||
|
error.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORTVA gzprintf OF((gzFile file, const char *format, ...));
|
||
|
/*
|
||
|
Converts, formats, and writes the arguments to the compressed file under
|
||
|
control of the format string, as in fprintf. gzprintf returns the number of
|
||
|
uncompressed bytes actually written, or 0 in case of error. The number of
|
||
|
uncompressed bytes written is limited to 8191, or one less than the buffer
|
||
|
size given to gzbuffer(). The caller should assure that this limit is not
|
||
|
exceeded. If it is exceeded, then gzprintf() will return an error (0) with
|
||
|
nothing written. In this case, there may also be a buffer overflow with
|
||
|
unpredictable consequences, which is possible only if zlib was compiled with
|
||
|
the insecure functions sprintf() or vsprintf() because the secure snprintf()
|
||
|
or vsnprintf() functions were not available. This can be determined using
|
||
|
zlibCompileFlags().
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
|
||
|
/*
|
||
|
Writes the given null-terminated string to the compressed file, excluding
|
||
|
the terminating null character.
|
||
|
|
||
|
gzputs returns the number of characters written, or -1 in case of error.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
|
||
|
/*
|
||
|
Reads bytes from the compressed file until len-1 characters are read, or a
|
||
|
newline character is read and transferred to buf, or an end-of-file
|
||
|
condition is encountered. If any characters are read or if len == 1, the
|
||
|
string is terminated with a null character. If no characters are read due
|
||
|
to an end-of-file or len < 1, then the buffer is left untouched.
|
||
|
|
||
|
gzgets returns buf which is a null-terminated string, or it returns NULL
|
||
|
for end-of-file or in case of error. If there was an error, the contents at
|
||
|
buf are indeterminate.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT gzputc OF((gzFile file, int c));
|
||
|
/*
|
||
|
Writes c, converted to an unsigned char, into the compressed file. gzputc
|
||
|
returns the value that was written, or -1 in case of error.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT gzgetc OF((gzFile file));
|
||
|
/*
|
||
|
Reads one byte from the compressed file. gzgetc returns this byte or -1
|
||
|
in case of end of file or error.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
|
||
|
/*
|
||
|
Push one character back onto the stream to be read as the first character
|
||
|
on the next read. At least one character of push-back is allowed.
|
||
|
gzungetc() returns the character pushed, or -1 on failure. gzungetc() will
|
||
|
fail if c is -1, and may fail if a character has been pushed but not read
|
||
|
yet. If gzungetc is used immediately after gzopen or gzdopen, at least the
|
||
|
output buffer size of pushed characters is allowed. (See gzbuffer above.)
|
||
|
The pushed character will be discarded if the stream is repositioned with
|
||
|
gzseek() or gzrewind().
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT gzflush OF((gzFile file, int flush));
|
||
|
/*
|
||
|
Flushes all pending output into the compressed file. The parameter flush
|
||
|
is as in the deflate() function. The return value is the zlib error number
|
||
|
(see function gzerror below). gzflush is only permitted when writing.
|
||
|
|
||
|
If the flush parameter is Z_FINISH, the remaining data is written and the
|
||
|
gzip stream is completed in the output. If gzwrite() is called again, a new
|
||
|
gzip stream will be started in the output. gzread() is able to read such
|
||
|
concatented gzip streams.
|
||
|
|
||
|
gzflush should be called only when strictly necessary because it will
|
||
|
degrade compression if called too often.
|
||
|
*/
|
||
|
|
||
|
/*
|
||
|
ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile file,
|
||
|
z_off_t offset, int whence));
|
||
|
|
||
|
Sets the starting position for the next gzread or gzwrite on the given
|
||
|
compressed file. The offset represents a number of bytes in the
|
||
|
uncompressed data stream. The whence parameter is defined as in lseek(2);
|
||
|
the value SEEK_END is not supported.
|
||
|
|
||
|
If the file is opened for reading, this function is emulated but can be
|
||
|
extremely slow. If the file is opened for writing, only forward seeks are
|
||
|
supported; gzseek then compresses a sequence of zeroes up to the new
|
||
|
starting position.
|
||
|
|
||
|
gzseek returns the resulting offset location as measured in bytes from
|
||
|
the beginning of the uncompressed stream, or -1 in case of error, in
|
||
|
particular if the file is opened for writing and the new starting position
|
||
|
would be before the current position.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT gzrewind OF((gzFile file));
|
||
|
/*
|
||
|
Rewinds the given file. This function is supported only for reading.
|
||
|
|
||
|
gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
|
||
|
*/
|
||
|
|
||
|
/*
|
||
|
ZEXTERN z_off_t ZEXPORT gztell OF((gzFile file));
|
||
|
|
||
|
Returns the starting position for the next gzread or gzwrite on the given
|
||
|
compressed file. This position represents a number of bytes in the
|
||
|
uncompressed data stream, and is zero when starting, even if appending or
|
||
|
reading a gzip stream from the middle of a file using gzdopen().
|
||
|
|
||
|
gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
|
||
|
*/
|
||
|
|
||
|
/*
|
||
|
ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile file));
|
||
|
|
||
|
Returns the current offset in the file being read or written. This offset
|
||
|
includes the count of bytes that precede the gzip stream, for example when
|
||
|
appending or when using gzdopen() for reading. When reading, the offset
|
||
|
does not include as yet unused buffered input. This information can be used
|
||
|
for a progress indicator. On error, gzoffset() returns -1.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT gzeof OF((gzFile file));
|
||
|
/*
|
||
|
Returns true (1) if the end-of-file indicator has been set while reading,
|
||
|
false (0) otherwise. Note that the end-of-file indicator is set only if the
|
||
|
read tried to go past the end of the input, but came up short. Therefore,
|
||
|
just like feof(), gzeof() may return false even if there is no more data to
|
||
|
read, in the event that the last read request was for the exact number of
|
||
|
bytes remaining in the input file. This will happen if the input file size
|
||
|
is an exact multiple of the buffer size.
|
||
|
|
||
|
If gzeof() returns true, then the read functions will return no more data,
|
||
|
unless the end-of-file indicator is reset by gzclearerr() and the input file
|
||
|
has grown since the previous end of file was detected.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
|
||
|
/*
|
||
|
Returns true (1) if file is being copied directly while reading, or false
|
||
|
(0) if file is a gzip stream being decompressed. This state can change from
|
||
|
false to true while reading the input file if the end of a gzip stream is
|
||
|
reached, but is followed by data that is not another gzip stream.
|
||
|
|
||
|
If the input file is empty, gzdirect() will return true, since the input
|
||
|
does not contain a gzip stream.
|
||
|
|
||
|
If gzdirect() is used immediately after gzopen() or gzdopen() it will
|
||
|
cause buffers to be allocated to allow reading the file to determine if it
|
||
|
is a gzip file. Therefore if gzbuffer() is used, it should be called before
|
||
|
gzdirect().
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT gzclose OF((gzFile file));
|
||
|
/*
|
||
|
Flushes all pending output if necessary, closes the compressed file and
|
||
|
deallocates the (de)compression state. Note that once file is closed, you
|
||
|
cannot call gzerror with file, since its structures have been deallocated.
|
||
|
gzclose must not be called more than once on the same file, just as free
|
||
|
must not be called more than once on the same allocation.
|
||
|
|
||
|
gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
|
||
|
file operation error, or Z_OK on success.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN int ZEXPORT gzclose_r OF((gzFile file));
|
||
|
ZEXTERN int ZEXPORT gzclose_w OF((gzFile file));
|
||
|
/*
|
||
|
Same as gzclose(), but gzclose_r() is only for use when reading, and
|
||
|
gzclose_w() is only for use when writing or appending. The advantage to
|
||
|
using these instead of gzclose() is that they avoid linking in zlib
|
||
|
compression or decompression code that is not used when only reading or only
|
||
|
writing respectively. If gzclose() is used, then both compression and
|
||
|
decompression code will be included the application when linking to a static
|
||
|
zlib library.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
|
||
|
/*
|
||
|
Returns the error message for the last error which occurred on the given
|
||
|
compressed file. errnum is set to zlib error number. If an error occurred
|
||
|
in the file system and not in the compression library, errnum is set to
|
||
|
Z_ERRNO and the application may consult errno to get the exact error code.
|
||
|
|
||
|
The application must not modify the returned string. Future calls to
|
||
|
this function may invalidate the previously returned string. If file is
|
||
|
closed, then the string previously returned by gzerror will no longer be
|
||
|
available.
|
||
|
|
||
|
gzerror() should be used to distinguish errors from end-of-file for those
|
||
|
functions above that do not distinguish those cases in their return values.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
|
||
|
/*
|
||
|
Clears the error and end-of-file flags for file. This is analogous to the
|
||
|
clearerr() function in stdio. This is useful for continuing to read a gzip
|
||
|
file that is being written concurrently.
|
||
|
*/
|
||
|
|
||
|
|
||
|
/* checksum functions */
|
||
|
|
||
|
/*
|
||
|
These functions are not related to compression but are exported
|
||
|
anyway because they might be useful in applications using the compression
|
||
|
library.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
|
||
|
/*
|
||
|
Update a running Adler-32 checksum with the bytes buf[0..len-1] and
|
||
|
return the updated checksum. If buf is Z_NULL, this function returns the
|
||
|
required initial value for the checksum.
|
||
|
|
||
|
An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
|
||
|
much faster.
|
||
|
|
||
|
Usage example:
|
||
|
|
||
|
uLong adler = adler32(0L, Z_NULL, 0);
|
||
|
|
||
|
while (read_buffer(buffer, length) != EOF) {
|
||
|
adler = adler32(adler, buffer, length);
|
||
|
}
|
||
|
if (adler != original_adler) error();
|
||
|
*/
|
||
|
|
||
|
/*
|
||
|
ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
|
||
|
z_off_t len2));
|
||
|
|
||
|
Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
|
||
|
and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
|
||
|
each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
|
||
|
seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.
|
||
|
*/
|
||
|
|
||
|
ZEXTERN uLong ZEXPORT crc32 OF((uLong crc, const Bytef *buf, uInt len));
|
||
|
/*
|
||
|
Update a running CRC-32 with the bytes buf[0..len-1] and return the
|
||
|
updated CRC-32. If buf is Z_NULL, this function returns the required
|
||
|
initial value for the for the crc. Pre- and post-conditioning (one's
|
||
|
complement) is performed within this function so it shouldn't be done by the
|
||
|
application.
|
||
|
|
||
|
Usage example:
|
||
|
|
||
|
uLong crc = crc32(0L, Z_NULL, 0);
|
||
|
|
||
|
while (read_buffer(buffer, length) != EOF) {
|
||
|
crc = crc32(crc, buffer, length);
|
||
|
}
|
||
|
if (crc != original_crc) error();
|
||
|
*/
|
||
|
|
||
|
/*
|
||
|
ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
|
||
|
|
||
|
Combine two CRC-32 check values into one. For two sequences of bytes,
|
||
|
seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
|
||
|
calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
|
||
|
check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
|
||
|
len2.
|
||
|
*/
|
||
|
|
||
|
|
||
|
/* various hacks, don't look :) */
|
||
|
|
||
|
/* deflateInit and inflateInit are macros to allow checking the zlib version
|
||
|
* and the compiler's view of z_stream:
|
||
|
*/
|
||
|
ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
|
||
|
const char *version, int stream_size));
|
||
|
ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
|
||
|
const char *version, int stream_size));
|
||
|
ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int level, int method,
|
||
|
int windowBits, int memLevel,
|
||
|
int strategy, const char *version,
|
||
|
int stream_size));
|
||
|
ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int windowBits,
|
||
|
const char *version, int stream_size));
|
||
|
ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
|
||
|
unsigned char FAR *window,
|
||
|
const char *version,
|
||
|
int stream_size));
|
||
|
#define deflateInit(strm, level) \
|
||
|
deflateInit_((strm), (level), ZLIB_VERSION, sizeof(z_stream))
|
||
|
#define inflateInit(strm) \
|
||
|
inflateInit_((strm), ZLIB_VERSION, sizeof(z_stream))
|
||
|
#define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
|
||
|
deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
|
||
|
(strategy), ZLIB_VERSION, sizeof(z_stream))
|
||
|
#define inflateInit2(strm, windowBits) \
|
||
|
inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
|
||
|
#define inflateBackInit(strm, windowBits, window) \
|
||
|
inflateBackInit_((strm), (windowBits), (window), \
|
||
|
ZLIB_VERSION, sizeof(z_stream))
|
||
|
|
||
|
/* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or
|
||
|
* change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if
|
||
|
* both are true, the application gets the *64 functions, and the regular
|
||
|
* functions are changed to 64 bits) -- in case these are set on systems
|
||
|
* without large file support, _LFS64_LARGEFILE must also be true
|
||
|
*/
|
||
|
#if defined(_LARGEFILE64_SOURCE) && _LFS64_LARGEFILE-0
|
||
|
ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
|
||
|
ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
|
||
|
ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
|
||
|
ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile));
|
||
|
ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
|
||
|
ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
|
||
|
#endif
|
||
|
|
||
|
#if !defined(ZLIB_INTERNAL) && _FILE_OFFSET_BITS-0 == 64 && _LFS64_LARGEFILE-0
|
||
|
# define gzopen gzopen64
|
||
|
# define gzseek gzseek64
|
||
|
# define gztell gztell64
|
||
|
# define gzoffset gzoffset64
|
||
|
# define adler32_combine adler32_combine64
|
||
|
# define crc32_combine crc32_combine64
|
||
|
# ifdef _LARGEFILE64_SOURCE
|
||
|
ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
|
||
|
ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int));
|
||
|
ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile));
|
||
|
ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile));
|
||
|
ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
|
||
|
ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
|
||
|
# endif
|
||
|
#else
|
||
|
ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
|
||
|
ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
|
||
|
ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
|
||
|
ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile));
|
||
|
ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
|
||
|
ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
|
||
|
#endif
|
||
|
|
||
|
/* hack for buggy compilers */
|
||
|
#if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
|
||
|
struct internal_state {int dummy;};
|
||
|
#endif
|
||
|
|
||
|
/* undocumented functions */
|
||
|
ZEXTERN const char * ZEXPORT zError OF((int));
|
||
|
ZEXTERN int ZEXPORT inflateSyncPoint OF((z_streamp));
|
||
|
ZEXTERN const uLongf * ZEXPORT get_crc_table OF((void));
|
||
|
ZEXTERN int ZEXPORT inflateUndermine OF((z_streamp, int));
|
||
|
|
||
|
#ifdef __cplusplus
|
||
|
}
|
||
|
#endif
|
||
|
|
||
|
#endif /* ZLIB_H */
|