Re: bus error in ps2pdf

[cjl@spamcop.net]

I now have access to a Debian Sparc box, and I can reproduce the  
problem. The crash happens in the pthreads library, and I find it  
confusing that this should happen on Linux/Sparc, but no other  
platforms (that I'm aware of). Looking at the code, there's nothing  
immediately obvious, unless there is a bug packing unions into  
structs, causing a pointer alignment problem. Actually, that does seem  
to be the problem: the second union does not sit on a 64 bit aligned  
boundary.

Anyway, in the short term, the solution is to disable threading in  
Ghostscript (it's rarely used, and only if the caller actually asks  
for it). To do so, change the definition in the Makefile after  
configure (or in Makefile.in) of the SYNC setting. By default it is:
SYNC=posync

and changing it to:

SYNC=nosync

will disable threading.

And Ghostscript should run as expected.

I intend to add a "nosync" option to configure for the next release,  
and I will obviously investigate solving the alignment problem.

HTH,

Chris



Quoting Jonathan Nieder <jrnieder@gmail.com>:

> Hi,
>
> Stéphane Glondu wrote:
>
> > ocaml-melt currently FTBFS on sparc [1] because of a bus error
> > provoked by ps2pdf. The bus error is easily reproduced by running
> > ps2pdf on the file available at [2]. This bug is not present with the
> > previous version, 8.71~dfsg2-10.
>
> Thanks for reporting it.  If anyone has time on a sparc, what might be
> useful is
>
> 	apt-get build-dep ghostscript
>
> 	git clone git://git.ghostscript.com/ghostscript.git
> 	cd ghostscript/gs
> 	# configure to minimize features (hopefully speeding up build)
> 	./autogen.sh -C \
> 		--disable-fontconfig \
> 		--disable-freetype --disable-cups --disable-gtk \
> 		--enable-dynamic --with-system-libtiff \
> 		--without-ijs --without-jbig2dec --without-jasper
> 	make
>
> 	# [2]
> 	lib/ps2pdfwr /path/to/doc.ps
>
> 	git show -s HEAD
>
> If that reproduces the error, it could be reported at
> http://bugs.ghostscript.com and I'd be glad to hear about it.
>
> 	git bisect start
> 	git bisect bad HEAD
> 	git bisect good ghostscript-8.71
>
> can guide through the bisection process afterwards to find the bad
> patch (which is hopefully an underalignment problem or similar).
>
> Any takers?
> Jonathan
>
> > [1]   
> > https://buildd.debian.org/fetch.cgi?pkg=ocaml-melt&arch=sparc&ver=1.3.0-2&stamp=1297644449&file=log&as=raw
> > [2] http://glondu.net/tmp/doc.ps
>
>
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