On 2021-01-11 Étienne Mollier wrote: > Lasse Collin, on 2021-01-11 19:19:09 +0200: > > I understand from your message that you got a different result. I > > wonder what would explain the difference. Your results are close to > > what I would expect with the "trap '' PIPE" patch. Are you sure you > > used the correctly patched xzcmp for testing? Otherwise I'm > > clueless what could explain the difference in our results. > > Oops, I forgot to pop the initial patch off the stack. The > `trap '' PIPE` was still present on top of the script. >_<" > When I rerun these tests without this on top, I see the same > good results as you. This explains that.
Good. :-) I noticed that in 2012 a similar issue was fixed in xzgrep. There SIGPIPE is detected more precisely with "kill -l $exit_status", so I adapted the xzdiff patch to use that correctly and committed it. The xzgrep method had a minor bug (it didn't check if the status was >= 128 indicating a signal). I also noticed another bug in xzgrep that it used gzip -q (which converts SIGPIPE to exit status 2) and ignored exit status 2 as SIGPIPE, which is bad because with bzip2 exit status 2 means corrupt input. These are now hopefully fixed too. Hopefully the removal of -q won't introduce a new bug in some special situation. One difference I noticed is that without -q bzip2 will display a fairly long error message if input is corrupt. With -q it is silent. I suspect the non-silent behavior is better with these scripts; just having exit status 2 from xzdiff/xzcmp isn't enough. With gzip and xz, -q or lack of -q makes no difference in this situation. With zstd the -q option is required though because otherwise zstd is noisy in normal situations. I also added zstd support to xzdiff/xzcmp. xzgrep already had it in xz.git. The scripts now have a different set of bugs than before. Hopefully the total number of bugs has not increased. :-) Thanks! -- Lasse Collin | IRC: Larhzu @ IRCnet & Freenode
