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.Dd November 10, 2018
.Dt DEFLATEGETDICTIONARY 3
.Os
.
.Sh NAME
.Nm deflateGetDictionary
.Nd deflate sliding dictionary
.
.Sh LIBRARY
.Lb libz
.
.Sh SYNOPSIS
.In zlib.h
.Ft int
.Fo deflateGetDictionary
.Fa "z_streamp strm"
.Fa "Bytef *dictionary"
.Fa "uInt *dictLength"
.Fc
.
.Sh DESCRIPTION
Returns the sliding dictionary
being maintained by deflate.
.Fa dictLength
is set to the number of bytes in the dictionary,
and that many bytes are copied to
.Fa dictionary .
.Fa dictionary
must have enough space,
where 32768 bytes is always enough.
If
.Fn deflateGetDictionary
is called with
.Fa dictionary
equal to
.Dv Z_NULL,
then only the dictionary length is returned,
and nothing is copied.
Similarly,
if
.Fa dictLength
is
.Dv Z_NULL ,
then it is not set.
.
.Pp
.Fn deflateGetDictionary
may return a length less than the window size,
even when more than the window size in input
has been provided.
It may return up to 258 bytes less in that case,
due to how zlib's implementation of deflate
manages the sliding window and lookahead for matches,
where matches can be up to 258 bytes long.
If the application needs the last window-size bytes of input,
then that would need to be saved by the application
outside of zlib.
.
.Sh RETURN VALUES
.Fn deflateGetDictionary
returns
.Dv Z_OK
on success,
or
.Dv Z_STREAM_ERROR
if the stream state is inconsistent.
.
.Sh SEE ALSO
.Xr deflateSetDictionary 3
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