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| -rw-r--r-- | Makefile | 1 | ||||
| -rw-r--r-- | inflateGetHeader.3 | 155 |
2 files changed, 156 insertions, 0 deletions
diff --git a/Makefile b/Makefile index 8a4f334..3f4245a 100644 --- a/Makefile +++ b/Makefile @@ -22,6 +22,7 @@ MAN += inflate.3 MAN += inflateCopy.3 MAN += inflateEnd.3 MAN += inflateGetDictionary.3 +MAN += inflateGetHeader.3 MAN += inflateInit.3 MAN += inflateInit2.3 MAN += inflateMark.3 diff --git a/inflateGetHeader.3 b/inflateGetHeader.3 new file mode 100644 index 0000000..e3e3cdd --- /dev/null +++ b/inflateGetHeader.3 @@ -0,0 +1,155 @@ +.Dd November 11, 2018 +.Dt INFLATEGETHEADER 3 +.Os +. +.Sh NAME +.Nm inflateGetHeader +.Nd get gzip header +. +.Sh LIBRARY +.Lb libz +. +.Sh SYNOPSIS +.In zlib.h +.Ft int +.Fn inflateGetHeader "z_streamp strm" "gz_headerp head" +. +.Sh DESCRIPTION +.Fn inflateGetHeader +requests that gzip header information +be stored in the provided +.Vt gz_header +structure. +.Fn inflateGetHeader +may be called after +.Xr inflateInit2 3 +or +.Xr inflateReset 3 , +and before the first call of +.Xr inflate 3 . +As +.Xr inflate 3 +processes the gzip stream, +.Fa head->done +is zero until the header is completed, +at which time +.Fa head->done +is set to one. +If a zlib stream is being decoded, +then +.Fa head->done +is set to -1 to indicate that + there will be no gzip header information forthcoming. +Note that +.Dv Z_BLOCK +or +.Dv Z_TREES +can be used to force +.Xr inflate 3 +to return immediately after +header processing is complete +and before any actual data is decompressed. +. +.Pp +The +.Fa text , +.Fa time , +.Fa xflags , +and +.Fa os +fields are filled in with the gzip header contents. +.Fa hcrc +is set to true if there is a header CRC. +.Po +The header CRC was valid if +.Fa done +is set to one. +.Pc +If +.Fa extra +is not +.Dv Z_NULL , +then +.Fa extra_max +contains the maximum number of bytes to write to +.Fa extra . +Once +.Fa done +is true, +.Fa extra_len +contains the actual extra field length, +and +.Fa extra +contains the extra field, +or that field truncated if +.Fa extra_max +is less than +.Fa extra_len . +If +.Fa name +is not +.Dv Z_NULL , +then up to +.Fa name_max +characters are written there, +terminated with a zero +unless the length is greater than +.Fa name_max . +If +.Fa comment +is not +.Dv Z_NULL , +then up to +.Fa comm_max +characters are written there, +terminated with a zero +unless the length is greater than +.Fa comm_max . +When any of +.Fa extra , +.Fa name , +or +.Fa comment +are not +.Dv Z_NULL +and the respective field +is not present in the header, +then that field is set to +.Dv Z_NULL +to signal its absence. +This allows the use of +.Xr deflateSetHeader 3 +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 feed. +. +.Pp +If +.Fn inflateGetHeader +is not used, +then the header information is simply discarded. +The header is always checked for validity, +including the header CRC if present. +.Xr inflateReset 3 +will reset the process to discard the header information. +The application would need to call +.Fn inflateGetHeader +again to retrieve the header from the next gzip stream. +. +.Pp +The +.Vt gz_headerp +type is documented in +.Xr deflateSetHeader 3 . +. +.Sh RETURN VALUES +.Fn inflateGetHeader +returns +.Dv Z_OK +if success, +or +.Dv Z_STREAM_ERROR +if the source stream state was inconsistent. |