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A massively spiffy yet delicately unobtrusive compression library. (grpc依赖)
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zlib/zlib.h

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/* zlib.h -- interface of the 'zlib' general purpose compression library
version 0.8 April 29th, 1995.
Copyright (C) 1995 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:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
Jean-loup Gailly Mark Adler
gzip@prep.ai.mit.edu madler@cco.caltech.edu
*/
#ifndef _ZLIB_H
#define _ZLIB_H
#include "zconf.h"
#define ZLIB_VERSION "0.8"
/*
The 'zlib' compression library provides in-memory compression and
decompression functions, including integrity checks of the uncompressed
data. This version of the library supports only one compression method
(deflation) but other algorithms may be added later and will have the same
stream interface.
For compression the application must provide the output buffer and
may optionally provide the input buffer for optimization. For decompression,
the application must provide the input buffer and may optionally provide
the output buffer for optimization.
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.
*/
typedef voidp (*alloc_func) __P((voidp opaque, uInt items, uInt size));
typedef void (*free_func) __P((voidp opaque, voidp address));
struct internal_state;
typedef struct z_stream_s {
Byte *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 */
Byte *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 *state; /* not visible by applications */
alloc_func zalloc; /* used to allocate the internal state */
free_func zfree; /* used to free the internal state */
voidp opaque; /* private data object passed to zalloc and zfree */
Byte data_type; /* best guess about the data type: ascii or binary */
} z_stream;
/*
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 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.
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).
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).
*/
/* constants */
#define Z_NO_FLUSH 0
#define Z_PARTIAL_FLUSH 1
#define Z_FULL_FLUSH 2
#define Z_FINISH 4
/* See deflate() below for the usage of these constants */
#define Z_OK 0
#define Z_STREAM_END 1
#define Z_ERRNO (-1)
#define Z_STREAM_ERROR (-2)
#define Z_DATA_ERROR (-3)
#define Z_MEM_ERROR (-4)
#define Z_BUF_ERROR (-5)
/* error codes for the compression/decompression functions */
#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
#define Z_BINARY 0
#define Z_ASCII 1
#define Z_UNKNOWN 2
/* Used to set the data_type field */
#define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
extern char *zlib_version;
/* The application can compare zlib_version and ZLIB_VERSION for consistency.
If the first character differs, the library code actually used is
not compatible with the zlib.h header file used by the application.
*/
/* basic functions */
extern int deflateInit __P((z_stream *strm, int level));
/*
Initializes the internal stream state for compression. The fields
zalloc, zfree and opaque must be initialized before by the caller.
If zalloc and zfree are set to Z_NULL, deflateInit updates them to
use default allocation functions.
The compression level must be Z_DEFAULT_COMPRESSION, or between 1 and 9:
1 gives best speed, 9 gives best compression. 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.
msg is set to null if there is no error message. deflateInit does not
perform any compression: this will be done by deflate().
*/
extern int deflate __P((z_stream *strm, int flush));
/*
Performs one or both of the following actions:
- Compress 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 and avail_in are updated and
processing will resume at this point for the next call of deflate().
- Provide more output starting at next_out and update next_out and avail_out
accordingly. This action is forced if the parameter flush is non zero.
Forcing flush frequently degrades the compression ratio, so this parameter
should be set only when necessary (in interactive applications).
Some output may be provided even if flush is not set.
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 the parameter flush is set to Z_PARTIAL_FLUSH, the current compression
block is terminated and flushed to the output buffer so that the
decompressor can get all input data available so far. For method 9, a future
variant on method 8, the current block will be flushed but not terminated.
If flush is set to Z_FULL_FLUSH, the compression block is terminated, a
special marker is output and the compression dictionary is discarded; this
is useful to allow the decompressor to synchronize if one compressed block
has been damaged (see inflateSync below). Flushing degrades compression and
so should be used only when necessary. Using Z_FULL_FLUSH too often can
seriously degrade the compression.
If the parameter flush is set to Z_FINISH, all pending input is processed,
all 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() 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.
*/
extern int deflateEnd __P((z_stream *strm));
/*
All dynamically allocated data structures for this stream are freed.
This function discards any unprocessed input and does not flush any
pending output.
deflateEnd 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).
*/
extern int inflateInit __P((z_stream *strm));
/*
Initializes the internal stream state for decompression. The fields
zalloc and zfree must be initialized before by the caller. If zalloc and
zfree are set to Z_NULL, deflateInit updates them to use default allocation
functions.
inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
enough memory. msg is set to null if there is no error message.
inflateInit does not perform any decompression: this will be done by
inflate().
*/
extern int inflate __P((z_stream *strm, int flush));
/*
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() always provides as much output as possible
(until no more input data or no more space in the output buffer).
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 the parameter flush is set to Z_PARTIAL_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 paramater other than Z_PARTIAL_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.
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_DATA_ERROR if the input data was corrupted, 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.
*/
extern int inflateEnd __P((z_stream *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.
*/
extern int deflateInit2 __P((z_stream *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 and zfree must be initialized before by the caller.
The method parameter is the compression method. It must be 8 in this
version of the library. (Method 9 will allow a 64K history buffer and
partial block flushes.)
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 (the value 16 will be allowed for method 9). 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.
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 strategy
parameter only affects the compression ratio but not the correctness of
the compressed output even if it is not set appropriately.
If next_in is not null, the library will use this buffer to hold also
some history information; the buffer must either hold the entire input
data, or have at least 1<<(windowBits+1) bytes and be writable. If next_in
is null, the library will allocate its own history buffer (and leave next_in
null). next_out need not be provided here but must be provided by the
application for the next call of deflate().
If the history buffer is provided by the application, next_in must
must never be changed by the application since the compressor maintains
information inside this buffer from call to call; the application
must provide more input only by increasing avail_in. next_in is always
reset by the library in this case.
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().
*/
extern int deflateCopy __P((z_stream *dest,
z_stream *source));
/*
Sets the destination stream as a complete copy of the source stream. If
the source stream is using an application-supplied history buffer, a new
buffer is allocated for the destination stream. The compressed output
buffer is always application-supplied. It's the responsability of the
application to provide the correct values of next_out and avail_out for the
next call of deflate.
This function is 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.
*/
extern int deflateReset __P((z_stream *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 NULL).
*/
extern int inflateInit2 __P((z_stream *strm,
int windowBits));
/*
This is another version of inflateInit with more compression options. The
fields next_out, zalloc and zfree 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 value 16 will be allowed soon). 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.
If next_out is not null, the library will use this buffer for the history
buffer; the buffer must either be large enough to hold the entire output
data, or have at least 1<<windowBits bytes. If next_out is null, the
library will allocate its own buffer (and leave next_out null). next_in
need not be provided here but must be provided by the application for the
next call of inflate().
If the history buffer is provided by the application, next_out must
never be changed by the application since the decompressor maintains
history information inside this buffer from call to call; the application
can only reset next_out to the beginning of the history buffer when
avail_out is zero and all output has been consumed.
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
windowBits < 8). msg is set to null if there is no error message.
inflateInit2 does not perform any compression: this will be done by
inflate().
*/
extern int inflateSync __P((z_stream *strm));
/*
Skips invalid compressed data until the special marker and a valid block
can be found, or until all available input is skipped. No output is provided.
inflateSync returns Z_OK if a valid block has been found, Z_BUF_ERROR if
no more input was provided, Z_DATA_ERROR if not valid block has been found,
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.
*/
extern int inflateReset __P((z_stream *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 NULL).
*/
/* 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, window size,
standard memory allocation functions). The source code of these
utility functions can easily be modified if you need special options.
*/
extern int compress __P((Byte *dest, uLong *destLen,
Byte *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 0.1% larger than
sourceLen plus 8 bytes. Upon exit, destLen is the actual size of the
compressed buffer.
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.
*/
extern int uncompress __P((Byte *dest, uLong *destLen,
Byte *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 compressed buffer.
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.
*/
typedef voidp gzFile;
extern gzFile gzopen __P((char *path, char *mode));
/*
Opens a gzip (.gz) file for reading or writing. The mode parameter
is as in fopen ("rb" or "wb"). gzopen can also 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 return 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).
*/
extern gzFile gzdopen __P((int fd, char *mode));
/*
gzdopen() associates a gzFile with the file descriptor fd. File
descriptors are obtained from calls like open, dup, creat, or pipe.
The mode parameter is as in fopen ("rb" or "wb").
gzdopen return NULL if there was insufficient memory to allocate
the (de)compression state.
*/
extern int gzread __P((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.
gzread returns the number of uncompressed bytes actually read (0 for
end of file, -1 for error). */
extern int gzwrite __P((gzFile file, voidp buf, unsigned len));
/*
Writes the given number of uncompressed bytes into the compressed file.
gzwrite returns the number of uncompressed bytes actually written
(0 in case of error).
*/
extern int gzflush __P((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 returns Z_OK if
the flush parameter is Z_FINISH and all output could be flushed.
gzflush should be called only when strictly necessary because it can
degrade compression.
*/
extern int gzclose __P((gzFile file));
/*
Flushes all pending output if necessary, closes the compressed file
and deallocates all the (de)compression state. The return value is the zlib
error number (see function gzerror below).
*/
extern char* gzerror __P((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.
*/
/* checksum functions */
/*
These functions are not related to compression but are exported
anyway because they might be useful in applications using the
compression library.
*/
extern uLong adler32 __P((uLong adler, Byte *buf, uInt len));
/*
Update a running Adler-32 checksum with the bytes buf[0..len-1] and
return the updated checksum. If buf is NULL, this function returns
the required initial value for the checksum.
An Adler-32 cheksum 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();
*/
extern uLong crc32 __P((uLong crc, Byte *buf, uInt len));
/*
Update a running crc with the bytes buf[0..len-1] and return the updated
crc. If buf is NULL, this function returns the required initial value
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();
*/
#ifndef _Z_UTIL_H
struct internal_state {int dummy;}; /* hack for buggy compilers */
#endif
#endif /* _ZLIB_H */