Wow, I completely overlooked that. I was convinced that
Gzip.input/Gzip.really_input returned the number of *compressed* characters
read. I misread "uncompresses up to len characters" as "advances the
compressed buffer up to len characters". The phrase "[Gzip.input] returns
the actual number of characters read" didn't help me either.

Anyway, thanks a lot, it's much simpler than I expected!




On Mon, Feb 2, 2015 at 6:38 PM, David Allsopp <dra-news@metastack.com>
wrote:

> Dhek Uir wrote:
> > But since camlzip does not have an input_value function, it seems I must
> set up
> > a buffer to decompress the data, then use Marshal to obtain input data
> from the
> > decompressed buffer. But if I use Marshal.from_string to read the
> decompressed
> > buffer, then I need to keep track of its position (which is not returned
> by
> > Marshal.from_string), and check whether the buffer is nearly empty, so
> that I
> > may need to re-read from the compressed in_channel, etc, etc. Did I miss
> the
> > right function again?
>
> Marshal has everything you need:
>
> let input_value ch =
>   let header = String.create Marshal.header_size
>   in
>     Gzip.really_input ch header 0 Marshal.header_size;
>     let buffer = String.create (Marshal.total_size header 0)
>     in
>       Gzip.really_input ch buffer Marshal.header_size (Marshal.data_size
> header 0);
>       String.unsafe_blit header 0 buffer 0 Marshal.header_size;
>       Marshal.from_string buffer 0
>
>
> David
>