Re: fun? with libsigsegv

Re: fun? with libsigsegv

[Eric Blake]

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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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