+ Copyright (C) 1995-2002 Jean-loup Gailly and Mark Adler +
+ This software is provided 'as-is', without any express or implied + warranty. In no event will the authors be held liable for any damages + arising from the use of this software. +
+ Permission is granted to anyone to use this software for any purpose, + including commercial applications, and to alter it and redistribute it + freely, subject to the following restrictions: +
+ This manual is converted from zlib.h by + piaip +
+ Visit + http://ftp.cdrom.com/pub/infozip/zlib/ + for the official zlib web page. +
+ +
+ + Compression can be done in a single step if the buffers are large + enough (for example if an input file is mmap'ed), or can be done by + repeated calls of the compression function. In the latter case, the + application must provide more input and/or consume the output + (providing more output space) before each call. +
+ + The library also supports reading and writing files in gzip (.gz) format + with an interface similar to that of stdio. +
+ + The library does not install any signal handler. The decoder checks + the consistency of the compressed data, so the library should never + crash even in case of corrupted input. +
+ +
+ This function can be used to compress a whole file at once if the + input file is mmap'ed.
+ 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.
+
+
+ + 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. +
+
+
+ This function can be used to decompress a whole file at once if the + input file is mmap'ed. +
+ + 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. +
+ +
+
+
+ + 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 or if there was + insufficient memory to allocate the (de)compression state ; errno + can be checked to distinguish the two cases (if errno is zero, the + zlib error is Z_MEM_ERROR). +
+
+
+ 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 gzdopen(dup(fd), mode). +
+ gzdopen returns NULL if there was insufficient memory to allocate + the (de)compression state. +
+
+
+ gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not + opened for writing. +
+
+
+ gzread returns the number of uncompressed bytes actually read (0 for + end of file, -1 for error). +
+
+
+
+
+
+
+ gzputs returns the number of characters written, or -1 in case of error. +
+
+
+ gzgets returns buf, or Z_NULL in case of error. +
+
+
+
+
+
+
+ gzflush should be called only when strictly necessary because it can + degrade compression. +
+
+
+ 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. +
+
+
+ gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET) +
+
+
+ + gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR) +
+
+
+
+
+
+
+
+
+
+ + The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9: + 1 gives best speed, 9 gives best compression, 0 gives no compression at + all (the input data is simply copied a block at a time). +
+ + Z_DEFAULT_COMPRESSION requests a default compromise between speed and + compression (currently equivalent to level 6). +
+ + deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not + enough memory, Z_STREAM_ERROR if level is not a valid compression level, + 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. deflateInit does not + perform any compression: this will be done by deflate(). +
+
+
+ + The detailed semantics are as follows. deflate performs one or both of the + following actions: + +
+ + Before the call of deflate(), the application should ensure that at least + one of the actions is possible, by providing more input and/or consuming + more output, and updating avail_in or avail_out accordingly ; avail_out + should never be zero before the call. The application can consume the + compressed output when it wants, for example when the output buffer is full + (avail_out == 0), or after each call of deflate(). If deflate 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. +
+ + If the parameter flush is set to Z_SYNC_FLUSH, all pending output is + flushed to the output buffer and the output is aligned on a byte boundary, so + that the decompressor can get all input data available so far. (In particular + avail_in is zero after the call if enough output space has been provided + before the call.) Flushing may degrade compression for some compression + algorithms and so it should be used only when necessary. +
+ + If flush is set to Z_FULL_FLUSH, all output is flushed as with + Z_SYNC_FLUSH, and the compression state is reset so that decompression can + restart from this point if previous compressed data has been damaged or if + random access is desired. Using Z_FULL_FLUSH too often can seriously degrade + the compression. +
+ + If deflate returns with avail_out == 0, this function must be called again + with the same value of the flush parameter and more output space (updated + avail_out), until the flush is complete (deflate returns with non-zero + avail_out). +
+ + If the parameter flush is set to Z_FINISH, pending input is processed, + pending output is flushed and deflate returns with Z_STREAM_END if there + was enough output space ; if deflate returns with Z_OK, this function must be + called again with Z_FINISH and more output space (updated avail_out) but no + more input data, until it returns with Z_STREAM_END or an error. After + deflate has returned Z_STREAM_END, the only possible operations on the + stream are deflateReset or deflateEnd. +
+ + Z_FINISH can be used immediately after deflateInit if all the compression + is to be done in a single step. In this case, avail_out must be at least + 0.1% larger than avail_in plus 12 bytes. If deflate does not return + Z_STREAM_END, then it must be called again as described above. +
+ + deflate() sets strm-> adler to the adler32 checksum of all input read + so far (that is, total_in bytes). +
+ + deflate() may update data_type if it can make a good guess about + the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered + binary. This field is only for information purposes and does not affect + the compression algorithm in any manner. +
+ + deflate() returns Z_OK if some progress has been made (more input + processed or more output produced), Z_STREAM_END if all input has been + 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 NULL), Z_BUF_ERROR if no progress is possible + (for example avail_in or avail_out was zero). +
+
+
+ + 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). +
+
+
+ + 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. msg is set to null if there is no error + message. inflateInit does not perform any decompression apart from reading + the zlib header if present: this will be done by inflate(). (So next_in and + avail_in may be modified, but next_out and avail_out are unchanged.) +
+
+
+ + The detailed semantics are as follows. inflate performs one or both of the + following actions: + +
+ + 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. +
+ + If the parameter flush is set to Z_SYNC_FLUSH, inflate flushes as much + output as possible to the output buffer. The flushing behavior of inflate is + not specified for values of the flush parameter other than Z_SYNC_FLUSH + and Z_FINISH, but the current implementation actually flushes as much output + as possible anyway. +
+ + 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 routine + may be used for the single inflate() call. +
+ + If a preset dictionary is needed at this point (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() 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 + adler32 checksum), Z_STREAM_ERROR if the stream structure was inconsistent + (for example if next_in or next_out was 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. In the Z_DATA_ERROR + case, the application may then call inflateSync to look for a good + compression block. +
+
+
+ + 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). +
+ + 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.
+ + 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), or Z_HUFFMAN_ONLY to force Huffman encoding only (no + string match). 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 and Z_HUFFMAN_ONLY. The strategy parameter only affects + the compression ratio but not the correctness of the compressed output even + if it is not set appropriately.
+ + deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough + memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid + method). msg is set to null if there is no error message. deflateInit2 does + not perform any compression: this will be done by deflate().
+
+
+ + 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 in + deflate or deflate2. Thus the strings most likely to be useful should be + put at the end of the dictionary, not at the front.
+ + 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.)
+ + deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a + parameter is invalid (such as NULL dictionary) 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().
+
+
+ + 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 NULL). msg is left unchanged in both source and + destination.
+
+
+ + deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source + stream state was inconsistent (such as zalloc or state being NULL).
+
+
+ + 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.
+
+
+ + 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. 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.
+ + inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough + memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative + memLevel). msg is set to null if there is no error message. inflateInit2 + does not perform any decompression apart from reading the zlib header if + present: this will be done by inflate(). (So next_in and avail_in may be + modified, but next_out and avail_out are unchanged.)
+
+
+ + inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a + parameter is invalid (such as NULL dictionary) 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().
+
+
+ + 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.
+
+
+ + inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source + stream state was inconsistent (such as zalloc or state being NULL). +
+
+ 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(); ++ +
+ + uLong crc = crc32(0L, Z_NULL, 0); + + while (read_buffer(buffer, length) != EOF) { + crc = crc32(crc, buffer, length); + } + if (crc != original_crc) error(); ++
+typedef struct z_stream_s {
+ Bytef *next_in; /* next input byte */
+ uInt avail_in; /* number of bytes available at next_in */
+ uLong total_in; /* total nb of input bytes read so far */
+
+ Bytef *next_out; /* next output byte should be put there */
+ uInt avail_out; /* remaining free space at next_out */
+ uLong total_out; /* total nb of bytes output so far */
+
+ char *msg; /* last error message, NULL if no error */
+ struct internal_state FAR *state; /* not visible by applications */
+
+ alloc_func zalloc; /* used to allocate the internal state */
+ free_func zfree; /* used to free the internal state */
+ voidpf opaque; /* private data object passed to zalloc and zfree */
+
+ int data_type; /* best guess about the data type: ascii or binary */
+ uLong adler; /* adler32 value of the uncompressed data */
+ uLong reserved; /* reserved for future use */
+} z_stream ;
+
+typedef z_stream FAR * z_streamp; ÿ
+
+
+ The application must update next_in and avail_in when avail_in has
+ dropped to zero. It must update next_out and avail_out when avail_out
+ has dropped to zero. The application must initialize zalloc, zfree and
+ opaque before calling the init function. All other fields are set by the
+ compression library and must not be updated by the application. + + The opaque value provided by the application will be passed as the first + parameter for calls of zalloc and zfree. This can be useful for custom + memory management. The compression library attaches no meaning to the + opaque value.
+ + zalloc must return Z_NULL if there is not enough memory for the object. + If zlib is used in a multi-threaded application, zalloc and zfree must be + thread safe.
+ + On 16-bit systems, the functions zalloc and zfree must be able to allocate + exactly 65536 bytes, but will not be required to allocate more than this + if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS, + pointers returned by zalloc for objects of exactly 65536 bytes *must* + have their offset normalized to zero. The default allocation function + provided by this library ensures this (see zutil.c). To reduce memory + requirements and avoid any allocation of 64K objects, at the expense of + compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h). +
+ + The fields total_in and total_out can be used for statistics or + progress reports. After compression, total_in holds the total size of + the uncompressed data and may be saved for use in the decompressor + (particularly if the decompressor wants to decompress everything in + a single step).
+ +
+#define Z_NO_FLUSH 0 +#define Z_PARTIAL_FLUSH 1 + /* will be removed, use Z_SYNC_FLUSH instead */ +#define Z_SYNC_FLUSH 2 +#define Z_FULL_FLUSH 3 +#define Z_FINISH 4 +/* Allowed flush values ; see deflate() below for details */ + +#define Z_OK 0 +#define Z_STREAM_END 1 +#define Z_NEED_DICT 2 +#define Z_ERRNO (-1) +#define Z_STREAM_ERROR (-2) +#define Z_DATA_ERROR (-3) +#define Z_MEM_ERROR (-4) +#define Z_BUF_ERROR (-5) +#define Z_VERSION_ERROR (-6) +/* Return codes for the compression/decompression functions. Negative + * values are errors, positive values are used for special but normal events. + */ + +#define Z_NO_COMPRESSION 0 +#define Z_BEST_SPEED 1 +#define Z_BEST_COMPRESSION 9 +#define Z_DEFAULT_COMPRESSION (-1) +/* compression levels */ + +#define Z_FILTERED 1 +#define Z_HUFFMAN_ONLY 2 +#define Z_DEFAULT_STRATEGY 0 +/* compression strategy ; see deflateInit2() below for details */ + +#define Z_BINARY 0 +#define Z_ASCII 1 +#define Z_UNKNOWN 2 +/* Possible values of the data_type field */ + +#define Z_DEFLATED 8 +/* The deflate compression method (the only one supported in this version) */ + +#define Z_NULL 0 /* for initializing zalloc, zfree, opaque */ + +#define zlib_version zlibVersion() +/* for compatibility with versions less than 1.0.2 */ ++ + +
+ Other functions: +