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zlib/zlib.h view on Meta::CPAN
*/
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), then next_in and avail_in are updated
accordingly, and processing will resume at this point for the next call of
inflate().
- Generate 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. If the
caller of inflate() does not provide both available input and available
output space, it is possible that there will be no progress made. 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.
To assist in this, on return inflate() always sets 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 of the uncompressed data for the
operation to complete. (The size of the uncompressed data may have been
saved by the compressor for this purpose.) The use of Z_FINISH is not
required to perform an inflation in one step. However it may be used to
inform inflate that a faster approach can be used for the single inflate()
call. Z_FINISH also informs inflate to not maintain a sliding window if the
stream completes, which reduces inflate's memory footprint. If the stream
does not complete, either because not all of the stream is provided or not
enough output space is provided, then a sliding window will be allocated and
inflate() can be called again to continue the operation as if Z_NO_FLUSH had
been used.
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 effects of the flush parameter in this implementation are
on the return value of inflate() as noted below, when inflate() returns early
when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
memory for a sliding window when Z_FINISH is used.
If a preset dictionary is needed after this call (see inflateSetDictionary
below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
strm->adler to the Adler-32 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 Adler-32
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 unless inflateGetHeader() is used. When processing
gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
produced so far. The CRC-32 is checked against the gzip trailer, as is the
uncompressed length, modulo 2^32.
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, in which case strm->msg points to a string with a more specific
error), Z_STREAM_ERROR if the stream structure was inconsistent (for example
next_in or next_out was Z_NULL, or the state was inadvertently written over
by the application), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR
if no progress was 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 to be attempted.
*/
zlib/zlib.h view on Meta::CPAN
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 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.
*/
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 Adler-32 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 at any
time to set the dictionary. If the provided dictionary is smaller than the
window and there is already data in the window, then the provided dictionary
will amend what's there. 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 Adler-32 value). inflateSetDictionary does not
perform any decompression: this will be done by subsequent calls of
inflate().
*/
ZEXTERN int ZEXPORT inflateGetDictionary OF((z_streamp strm,
Bytef *dictionary,
uInt *dictLength));
/*
Returns the sliding dictionary being maintained by inflate. dictLength is
set to the number of bytes in the dictionary, and that many bytes are copied
to dictionary. dictionary must have enough space, where 32768 bytes is
always enough. If inflateGetDictionary() is called with dictionary equal to
Z_NULL, then only the dictionary length is returned, and nothing is copied.
Similarly, if dictLength is Z_NULL, then it is not set.
inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
stream state is inconsistent.
*/
ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
/*
Skips invalid compressed data until a possible full flush point (see above
zlib/zlib.h view on Meta::CPAN
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 -65536 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 parameters 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 *,
z_const 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));
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