Re: [Matplotlib-users] Segmentation fault from inside transforms

[Ted D. <ted...@jp...>]

>It couldn't be the exact same error, because _na_transforms did not
>exist in 0.62.4.  Do you mean that you got a segfault on the same line
>in _transform?

Sorry - that's what I meant.  It looks like I was a little mistaken.  I 
didn't realize that there are 2 versions of __Py_PackageContext() in the 
same file.  I was orginally looking at the Windows version (I'm building on 
linux).

However, if the linux version looks like this (unmodified):

char *__Py_PackageContext()     { return _Py_PackageContext; }

I get a segmentation fault at the return line.

I then added a print statement to it:

char *__Py_PackageContext()
{
    std::cerr << "context 0\n";
    return _Py_PackageContext;
}

and then everything works!  Off the top of my head, it might be a case of 
C++ static object initialization problems but I can't find any obvious 
places that might be happening.

Ted

At 01:00 PM 10/21/2004, John Hunter wrote:
> >>>>> "Ted" == Ted Drain <ted...@jp...> writes:
>
>     Ted> I'm trying to build matplotlib and I'm getting a segmentation
>     Ted> fault when I do: from matplotlib import *
>
>     Ted> I've traced the fault down to the transforms module.
>
>     Ted> My first attempt used: gcc 3.3.2 Python 2.3.3 numarray 1.1
>     Ted> gdmodule 0.52 gd 2.0.28 freetype 2.1.9 agg 22 matplotlib
>     Ted> 0.63.4
>
>Standard issue stuff - very close to what most people are using w/o
>incident.  Hmmmm....
>
>     Ted> In this version _na_transform segementation faults at this
>     Ted> line: static _transforms_module* _transforms = new
>     Ted> _transforms_module;
>
>     Ted> I traced the fault down to the ExtensionModuleBaseClass where
>     Ted> it attempts to call: __Py_PackageContext()
>
>     Ted> It looks to me like this function is trying to access the
>     Ted> variable (which it dereferences WITHOUT checking for a null
>     Ted> pointer).  static char **ptr__Py_PackageContext = NULL;
>
>Could you try editing it an adding the NULL test; if this works can
>you submit a patch pack to be and a bug report to the pycxx sf site?
>
>     Ted> This ptr gets init'ed in the function
>     Ted> InitialisePythonIndirectInterface() but I can't find anywhere
>     Ted> that function is being called.
>
>     Ted> FYI: I also tried matplotlib 0.62.4 and I get the same error.
>
>It couldn't be the exact same error, because _na_transforms did not
>exist in 0.62.4.  Do you mean that you got a segfault on the same line
>in _transform?
>
>Thanks,
>JDH