GNU bug report logs - #18266
grep -P and invalid exits with error

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Message #49 received at 18266 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Santiago <santiago <at> debian.org>, 758105 <at> bugs.debian.org
Cc: 18266 <at> debbugs.gnu.org, Vincent Lefevre <vincent <at> vinc17.net>
Subject: Re: grep -P and invalid exits with error
Date: Fri, 29 Aug 2014 06:43:45 -0700

Thanks, but that patch seems to depend on libpcre internals, in that it 
"knows" that pcre_exec cannot possibly succeed without first checking 
its entire input buffer for invalid UTF-8 bytes.  Even if that's true 
now, it reflects a performance bug that might be fixed in a future 
libpcre version.

Also, I don't see why grep needs to copy the buffer when there's an 
encoding error.  Why not simply rerun the matcher on the initial prefix 
that doesn't have an encoding-error byte, and then (if that doesn't find 
a match), try matching the suffix after the encoding-error byte?  This 
approach would not only avoid the buffer copy, it would avoid knowledge 
of libpcre internals.

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