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

[Antonio Diaz Diaz]

Pierre Neidhardt wrote:
> > If you write incomplete data (maybe because the file is truncated), and
> > then call LZ_decompress_read until it returns 0 (without calling
> > LZ_(de)compress_finish nor reading until LZ_(de)compress_finished
> > returns 1), then the decompressed data produced will be also truncated.
> > No error is reported because the decoder is waiting more input.
>
> And that's fine since the input is a stream, isn't it?
> So when I'm done with the stream, all the data has been written/read,
> then the compressed data will be complete, right?  Calling
> LZ_(de)compress_finish then should not change anything, or will it?

You have two problems here:

For decompression the problem is that your code is not robust. If you 
don't do it the right way and your assumption that "the input is a 
stream" happens to be false, then your code will silently cause data loss.

For compression, if you don't call LZ_compress_finish or do not read 
until LZ_compress_finished returns 1, you'll produce a truncated stream 
which, BTW, won't be detected as truncated by your non-robust 
decompression code.