I try to log all the output of a program written in Python and C to a
buffer. I create a pipe, redirect stdout to its write-end and then read
its content afterward. However, printing from Python fires "IOError:
[Errno 9] Bad file descriptor". Please see the attached test-case.

It is happening on Windows XP, Python 2.6 and MinGW GCC and I used this
to compile:
gcc -o std.exe std.c -Ic:/dev/include/python2.6 -l python26

PS: It might be that the problem is that Python was compiled with
MSVC2008 and I'm using MinGW but I'm not sure...

Can a Windows guru comment on whether this is a Python issue or not?

Yes, mingw uses a different C runtime (msvcrt.dll) than Python (msvcr90.dll), so file descriptors are completely different and this causes the error.

I can see two solutions:

- Use the same compiler as python26; I've also heard about a way to force mingw to use msvcr90.dll.

- Avoid to pass mingw file descriptors to the python interpreter.  This requires more work: create a PyTypeObject that mimics a file object, and set this as sys.stdout. It should be enough to implement .write() and .flush(); you can use the C system calls (fwrite, fflush or whatever) there, and the file descriptors are used in a consistent way.