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

[Antonio Diaz Diaz]

Pierre Neidhardt wrote:
> When the byte count of written data is equal to the size of the input
> chunk, we have a guarantee that the result is complete (i.e. not
> truncated), right?

It means that you have written all the chunk to lzlib. It does not mean 
that lzlib has produced all the output nor that you have read all the 
output from lzlib.


> Also, is there a different between
>     LZ_compress_finished(...) == 1
> and
>     LZ_compress_read() == 0

A world of difference. 'LZ_compress_read() == 0' means nothing:

-------------------------------------------------------------------
http://www.nongnu.org/lzip/manual/lzlib_manual.html#Compression-functions
    The 'LZ_compress_read' function reads up to size bytes from the 
stream pointed to by encoder, storing the results in buffer.

    The return value is the number of bytes actually read. This might 
be less than size; for example, if there aren't that many bytes left in 
the stream or if more bytes have to be yet written with the 
'LZ_compress_write' function. Note that reading less than size bytes is 
not an error.
-------------------------------------------------------------------

For example, the member trailer is not produced until LZ_compress_finish 
is called, and is not guaranteed to have been read until 
'LZ_compress_finished() == 1'.