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Re: [Cygwin64] dash segfault


On Mar 10 11:18, Corinna Vinschen wrote:
> On Mar 10 00:05, Peter Rosin wrote:
> > On 2013-03-09 13:50, Corinna Vinschen wrote:
> > > On Mar  8 23:13, Peter Rosin wrote:
> > >> Hi!
> > >>
> > >> I doubt there is a shortage of obscure things to track down in the land
> > >> of 64-bit, but while building a package using the stuff from install/release
> > >> I noticed a segfault in dash when it ran a libtool script to generate a
> > >> dll. Retrying got the dll built correctly.
> > >>
> > >> Fact is, I do see segfaults once in a while, but retrying has always helped
> > >> so far, so I haven't pursued it.
> > >>
> > >> How do I set up a debugger to get more info than the below stackdump?
> > > 
> > > I added a 64 bit Cygwin GDB package to the install area a couple
> > > of days ago.  I guess a debug version of dash (especially built w/o
> > > optimization) won't hurt either.
> > 
> > Ok, I recompiled dash locally (.../configure CFLAGS=-g --prefix=/usr)
> > and used CYGWIN='error_start=C:\...\bin\dumper.exe' and got myself a
> > core file...
> > 
> > Not much appears to be going on though, suggestions are welcome...
> 
> Hmm. What about error_start=C:\...\gdb.exe?  Maybe that gives you a bit
> more "life" information.

Btw., I just checked the RIP value in the stackdump output you sent.

Assuming you're using cygwin1.dll from the base package, this would be
ptmalloc3.cc, line 792.  This in turn would point to a call of free() on
something not a valid pointer.

Assuming you're using cygwin1.dll from the cygwin-1.7.18-2.tar.bz2
package in the 64bit/release area, that would be malloc-private.h, line 88.

That would be a mutex_unlock call from within the ptmalloc3 code.

The missing stack is a pity, though, since that leaves us with no
trace about the cicumstances.  If you reproduce the same with a 
non-optimized debug version of dash, does the stackdump contain a
stack backtrace?


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat


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