On 27 Mar 2013, at 19:54, José Mejuto wrote:
> El 27/03/2013 19:22, Michalis Kamburelis escribió:
>
>> Google found an old thread on lazarus mailing list about this ("FPC,
>> gzip and stream") but without any solution, everything mentioned there
>> has either the limitations of TCompressionStream/TDecompressionStream
>> (no gzip format) or TGZFileStream (not able to work wit ObjectPascal
>> streams).
>>
>
> Hello,
>
> .gz is a quite simple format, but it can not be implemented as a TStream
> (only) descendant because in a single .gz file many files could be added so
> something like the class to handle .zip files should be used.
Sorry to just drop in on this quite late, but isn't gzip a compression
algorithm and not a file format as such? gzip (the command line utility) only
compresses one file and *doesn't* put this in a multi-file container. To get
`multi-file gzips`, you will first want to bundle the files and compress this
bundle (files -> tar -> gzip) or compress the files separately and then bundle
them together (files -> multiple separate gzipped files -> tar). Or are we
talking about a different gzip here?
So basically (to answer to the subject of this mail), you will only need a
stream that implements this algorithm, which you could quite easily write
yourself. Take a look at zlibar, it's a project that iirc implements an archive
format that uses gzip. Now there are two functions in there that compress and
respectively decompress a stream and return the result, also as a TStream
descendant. If you cannot find this easily just say it, I've got the code (or
at the very least these two functions) lying around.
If I just said anything anyone has already mentioned, please forgive me, I've
only just read this message and thought to elaborate a bit on it :-)
--
Ewald
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