Re: [Lzip-bug] [lzlib] Help with Scheme bindings (for GNU Guix)

[Antonio Diaz Diaz]

Hi Pierre,

Pierre Neidhardt wrote:
> (If you can't read Scheme, I can help, no problem.)

Thanks. I'm not a Scheme programmer.


> 1. When am I supposed to call lz_decompress_finish?  In the above
> lzread!, you'll see it's commented and it seems to work nonetheless.  If
> I uncomment it, it crashes.

You may call LZ_decompress_finish as many times as you wish, but never 
before all the compresed data has been written with LZ_decompress_write. 
If you call LZ_decompress_finish prematurely, lzlib will report 
truncated data. If you don't call it, a truncated member may not be 
detected.


> 2. It's unclear in the manual if the lz-decompress-read reads all the
> bytes that were written.  Am I supposed to loop until no more bytes are
> read?

It can't be guaranteed that LZ_decompress_read reads all the bytes 
written because up to more than 7000 decompressed bytes can be produced 
for each compressed byte. You may either read in a loop or alternate 
write/read calls in a loop.


> 3. In both functions, should we *compress_write everything first, then
> *compress_read as much as we can?  Or chain write-read calls like in
> bbexample.c?

Both ways work.


> 4. In lzwrite, is "written" the number of uncompressed bytes and "read" the
> number of compressed bytes?

Yes.


Regards,
Antonio.