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Re: fun? with libsigsegv
- From: Eric Blake <ebb9 at byu dot net>
- To: cygwin-talk at cygwin dot com
- Date: Sat, 18 Jul 2009 06:55:52 -0600
- Subject: Re: fun? with libsigsegv
- References: <loom.20090717T213846-627@post.gmane.org> <loom.20090717T224758-877@post.gmane.org>
- Reply-to: The Vulgar and Unprofessional Cygwin-Talk List <cygwin-talk at cygwin dot com>
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According to Eric Blake on 7/17/2009 4:50 PM:
>> Without libsigsegv, things operate as before. But with libsigsegv, I now
> see...
>
> Aargh. I spoke too soon. For my previous mail, I fat-fingered my command
> line
I hate it when a typo changes the course of my entire weekend. I thought
for sure that I was home free, until I realized that I wasn't testing the
snapshot like I thought I was. Almost as bad as the feeling you get when
you see a hippo charging you.
With m4, it's interesting how many pieces have to interact, and yet how
concise a reproducible test case is:
echo | m4 >&-
It requires cygwin 1.7 (1.5 passes, as does Linux), closed stdout (who
does that, normally?), and libsigsegv (no crash if the library is omitted
from m4) - in other words, not your most common combinations.
At any rate, it looks like the crash can be independently avoided from any
one of three locations (gnulib's use of fflush[1], newlib's fault in
fflush[2], and libsigsegv's overreacting to faults that cygwin wants to
claim[3]). But although any one of the patches fixes the simple m4 test
case, I'm hoping that all three get accepted in their respective upstream
repositories.
[1] http://thread.gmane.org/gmane.comp.lib.gnulib.bugs/18046/focus=18052
[2] http://sourceware.org/ml/newlib/2009/msg00770.html
[3] URL to libsigsegv patch not yet known - wanna help me write it? ;)
- --
Don't work too hard, make some time for fun as well!
Eric Blake ebb9@byu.net
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