[GRASS-dev] Re: ctypes problem with Vect_open_old

[Glynn Clements]

Martin Landa wrote:

> > I can't reproduce this. Running it under GDB might help, or it might
> > not; memory corruption is like that.

> It seems to crash at [1].

That's where it trips over the memory corruption, but it doesn't tell
us where it happened. Printing the contents of the various structures
(Map_info, Plus_head, etc) might provide some clues.

> In summary, the sample script works on
> 
> * my laptop (Debian GNU/Linux unstable 32bit, gcc 4.6.1, python 2.6.7)
> - GRASS compiled *without* LFS
> 
> and fails on
> 
> * testing server (Debian GNU/Linux stable 64bit, gcc 4.4.5, python
> 2.6.6) - GRASS compiled *with* LFS

LFS should be a no-op on a 64-bit platform, i.e. off_t should always
be 64-bit.

FWIW, it works for me on a 32-bit platform with LFS enabled.

Have you tried writing an equivalent C program and seeing whether that
works? We might be looking at a bug which has nothing to do with
Python or ctypes. As the script is much simpler than a typical v.* C
program, it's possible that some initialisation is being skipped.

-- 
Glynn Clements <glynn at gclements.plus.com>