bug#75924: maint: fix s390 buffer flushes

[Eduard Stefes]

Hi,

On Wed, 2025-01-29 at 10:58 -0800, Paul Eggert wrote:
> Thanks for the bug report. I installed the attached, a bit simpler
> than 
> the patch you suggested; can you please give it a try?
changing the call fill_inbuff(1) to fill_inbuff(0) will not work.
dfltcc works on the outbuf, and fill_inbuff will eventually call
flush_window in case it hits EOF && 0. But it will NOT call
flush_outbuf() which we need in this case.



> 
> Also, is there a related bug near dfltcc.c line 375? That is, when 
> (inptr == insize && fill_inbuf (1) == EOF && param->cf), won't insize
> then be zero, so that gzip will go into an infinite loop attempting
> to 
> read past EOF?
I will think about this and try to come up with a test for it. To me it
looks like inbuf is preallocated (gzip.c:135) so it might be ok to read
past EOF and just compress zeros. The logic around it should prevent
access past inbuf[MAX]. But better be save then sorry.  

In that matter, should I extract the failing gzip tests from rsyslog
and add them to the gzip test suit?

-- 
Eduard Stefes <Eduard.Stefes@ibm.com>