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| -rw-r--r-- | Makefile | 2 | ||||
| -rw-r--r-- | inflateInit2.3 | 170 |
2 files changed, 172 insertions, 0 deletions
diff --git a/Makefile b/Makefile index 970c6a1..fc85d08 100644 --- a/Makefile +++ b/Makefile @@ -16,10 +16,12 @@ MAN += deflatePending.3 MAN += deflatePrime.3 MAN += deflateReset.3 MAN += deflateSetDictionary.3 +MAN += deflateSetHeader.3 MAN += deflateTune.3 MAN += inflate.3 MAN += inflateEnd.3 MAN += inflateInit.3 +MAN += inflateInit2.3 MAN += uncompress.3 MAN += zlibCompileFlags.3 MAN += zlibVersion.3 diff --git a/inflateInit2.3 b/inflateInit2.3 new file mode 100644 index 0000000..84e5d7d --- /dev/null +++ b/inflateInit2.3 @@ -0,0 +1,170 @@ +.Dd November 11, 2018 +.Dt INFLATEINIT2 3 +.Os +. +.Sh NAME +.Nm inflateInit2 +.Nd inflate compression options +. +.Sh LIBRARY +.Lb libz +. +.Sh SYNOPSIS +.In zlib.h +.Ft int +.Fn inflateInit2 "z_streamp strm" "int windowBits" +. +.Sh DESCRIPTION +This is another version of +.Xr inflateInit 3 +with an extra parameter. +The fields +.Fa next_in , +.Fa avail_in , +.Fa zalloc , +.Fa zfree +and +.Fa opaque +must be initialized before by the caller. +. +.Pp +The +.Fa 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 +.Xr inflateInit 3 +is used instead. +.Fa windowBits +must be greater than or equal to the +.Fa windowBits +value provided to +.Xr deflateInit2 3 +while compressing, +or it must be equal to 15 if +.Xr deflateInit2 3 +was not used. +If a compressed stream with a larger window size +is given as input, +.Xr inflate 3 +will return with the error code +.Dv Z_DATA_ERROR +instead of trying to allocate a larger window. +. +.Pp +.Fa windowBits +can also be zero +to request that +.Xr inflate 3 +use the window size +in the zlib header +of the compressed stream. +. +.Pp +.Fa windowBits +can also be -8..-15 +for raw inflate. +In this case, +.Fa -windowBits +determines the window size. +.Xr inflate 3 +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 +.Xr deflateInit2 3 +applies to the magnitude of +.Fa windowBits . +. +.Pp +.Fa windowBits +can also be greater than 15 +for optional gzip decoding. +Add 32 to +.Fa windowBits +to enable zlib and gzip decoding +with automatic header detection, +or add 16 to decode only the gzip format +.Po +the zlib format will return a +.Dv Z_DATA_ERROR +.Pc . +If a gzip stream is being decoded, +.Fa strm->adler +is a CRC-32 instead of an Adler-32. +Unlike the +.Xr gunzip 1 +utility and +.Xr gzread 3 , +.Xr inflate 3 +will not automatically decode +concatenated gzip streams. +.Xr inflate 3 +will return +.Dv Z_STREAM_END +at the end of the gzip stream. +The state would need to be reset +to continue decoding a subsequent gzip stream. +. +.Pp +.Fn inflateInit2 +does not perform any decompression +apart from possibly reading the zlib header if present: +actual decompression will be done by +.Xr inflate 3 . +.Po +So +.Fa next_in +and +.Fa avail_in +may be modified, +but +.Fa next_out +and +.Fa avail_out +are unused and unchanged. +.Pc +The current implementation of +.Fn inflateInit2 +does not process any header information \(em +that is deferred until +.Xr inflate 3 +is called. +. +.Sh RETURN VALUES +.Fn inflateInit2 +returns +.Dv Z_OK +if success, +.Dv Z_MEM_ERROR +if there was not enough memory, +.Dv Z_VERSION_ERROR +if the zlib library version +is incompatible with the version assumed by the caller, +or +.Dv Z_STREAM_ERROR +if the parameters are invalid, +such as a null pointer to the structure. +.Fa msg +is set to null if there is no error message. +. +.Sh SEE ALSO +.Xr deflateInit2 3 , +.Xr inflateInit 3 |