zlib decompression More...

#include "zutil.h"
#include "inftrees.h"
#include "inflate.h"
#include "inffast.h"
#include "inffixed.h"

Macros
#define	UPDATE_CHECK(check, buf, len) (state->flags ? crc32(check, buf, len) : adler32(check, buf, len))

#define	CRC2(check, word)

#define	CRC4(check, word)

#define	LOAD()

#define	RESTORE()

#define	INITBITS()

#define	PULLBYTE()

#define	NEEDBITS(n)

#define	BITS(n) ((unsigned)hold & ((1U << (n)) - 1))

#define	DROPBITS(n)

#define	BYTEBITS()

Functions
int ZEXPORT	inflateResetKeep (z_streamp strm)

int ZEXPORT	inflateReset (z_streamp strm)
	This function is equivalent to inflateEnd followed by inflateInit, but does not free and reallocate the internal decompression state.

int ZEXPORT	inflateReset2 (z_streamp strm, int windowBits)
	This function is the same as inflateReset, but it also permits changing the wrap and window size requests.

int ZEXPORT	inflateInit2_ (z_streamp strm, int windowBits, const char *version, int stream_size)
	This is another version of inflateInit with an extra parameter.

int ZEXPORT	inflateInit_ (z_streamp strm, const char *version, int stream_size)
	Initializes the internal stream state for decompression.

int ZEXPORT	inflatePrime (z_streamp strm, int bits, int value)
	This function inserts bits in the inflate input stream.

int ZEXPORT	inflate (z_streamp strm, int flush)
	Decompresses as much data as possible, and stops when the input buffer becomes empty or the output buffer becomes full.

int ZEXPORT	inflateEnd (z_streamp strm)
	All dynamically allocated data structures for this stream are freed.

int ZEXPORT	inflateGetDictionary (z_streamp strm, Bytef dictionary, uInt dictLength)
	Returns the sliding dictionary being maintained by inflate.

int ZEXPORT	inflateSetDictionary (z_streamp strm, const Bytef *dictionary, uInt dictLength)
	Initializes the decompression dictionary from the given uncompressed byte sequence.

int ZEXPORT	inflateGetHeader (z_streamp strm, gz_headerp head)
	Requests that gzip header information be stored in the provided gz_header structure.

int ZEXPORT	inflateSync (z_streamp strm)
	Skips invalid compressed data until a possible full flush point (see above for the description of deflate with Z_FULL_FLUSH) can be found, or until all available input is skipped.

int ZEXPORT	inflateSyncPoint (z_streamp strm)

int ZEXPORT	inflateCopy (z_streamp dest, z_streamp source)
	Sets the destination stream as a complete copy of the source stream.

int ZEXPORT	inflateUndermine (z_streamp strm, int subvert)

int ZEXPORT	inflateValidate (z_streamp strm, int check)

long ZEXPORT	inflateMark (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.

unsigned long ZEXPORT	inflateCodesUsed (z_streamp strm)

Detailed Description

zlib decompression

Macro Definition Documentation

◆ BYTEBITS

#define BYTEBITS ( )

Value:

    do { \
        hold >>= bits & 7; \
        bits -= bits & 7; \
    } while (0)

◆ CRC2

#define CRC2	(	check,
		word
	)

Value:

    do { \
        hbuf[0] = (unsigned char)(word); \
        hbuf[1] = (unsigned char)((word) >> 8); \
        check = crc32(check, hbuf, 2); \
    } while (0)

◆ CRC4

#define CRC4	(	check,
		word
	)

Value:

    do { \
        hbuf[0] = (unsigned char)(word); \
        hbuf[1] = (unsigned char)((word) >> 8); \
        hbuf[2] = (unsigned char)((word) >> 16); \
        hbuf[3] = (unsigned char)((word) >> 24); \
        check = crc32(check, hbuf, 4); \
    } while (0)

◆ DROPBITS

#define DROPBITS ( n )

Value:

    do { \
        hold >>= (n); \
        bits -= (unsigned)(n); \
    } while (0)

◆ INITBITS

#define INITBITS ( )

Value:

    do { \
        hold = 0; \
        bits = 0; \
    } while (0)

◆ LOAD

#define LOAD ( )

Value:

    do { \
        put = strm->next_out; \
        left = strm->avail_out; \
        next = strm->next_in; \
        have = strm->avail_in; \
        hold = state->hold; \
        bits = state->bits; \
    } while (0)

◆ NEEDBITS

#define NEEDBITS ( n )

Value:

    do { \
        while (bits < (unsigned)(n)) \
            PULLBYTE(); \
    } while (0)

◆ PULLBYTE

#define PULLBYTE ( )

Value:

    do { \
        if (have == 0) goto inf_leave; \
        have--; \
        hold += (unsigned long)(*next++) << bits; \
        bits += 8; \
    } while (0)

◆ RESTORE

#define RESTORE ( )

Value:

    do { \
        strm->next_out = put; \
        strm->avail_out = left; \
        strm->next_in = next; \
        strm->avail_in = have; \
        state->hold = hold; \
        state->bits = bits; \
    } while (0)

Function Documentation

◆ inflateInit2_()

int ZEXPORT inflateInit2_	(	z_streamp	strm,
		int	windowBits,
		const char *	version,
		int	stream_size
	)

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 Adler-32 or a CRC-32 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 CRC-32 instead of an Adler-32. Unlike the gunzip utility and gzread() (see below), inflate() will not automatically decode concatenated gzip members. inflate() will return Z_STREAM_END at the end of the gzip member. The state would need to be reset to continue decoding a subsequent gzip member. This must* be done if there is more data after a gzip member, in order for the decompression to be compliant with the gzip standard (RFC 1952).

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.

◆ inflateInit_()

int ZEXPORT inflateInit_	(	z_streamp	strm,
		const char *	version,
		int	stream_size
	)

Initializes the internal stream state for decompression.

The fields z_stream_s::next_in, avail_in, zalloc, zfree and opaque must be initialized before by the caller. In the current version of inflate, the provided input is not read or consumed. The allocation of a sliding window will be deferred to the first call of inflate (if the decompression does not complete on the first call). If zalloc and zfree are set to Z_NULL, inflateInit updates them to use default allocation functions. total_in, total_out, adler, and msg are initialized.

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. Actual decompression will be done by inflate(). So next_in, and avail_in, 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.

Macros

Functions

Detailed Description

Macro Definition Documentation

◆ BYTEBITS

◆ CRC2

◆ CRC4

◆ DROPBITS

◆ INITBITS

◆ LOAD

◆ NEEDBITS

◆ PULLBYTE

◆ RESTORE

Function Documentation

◆ inflateInit2_()

◆ inflateInit_()