the direct call to the getdents syscall is broken on x32.  there, the first two args are not unsigned long, but unsigned long long.  patch attached to fix the issue.

What is x32?

Answering my own question I believe x32 is the new ABI being worked on as described in http://lwn.net/Articles/456731/.

In that light, your patch makes sense assuming the __ILP32__ define is something gcc's cpp will always be defining when targeting x32.  I will apply it.

for reference - https://sites.google.com/site/x32abi/

$ echo | gcc -m32 -E -P -dD - | grep LP
<nothing>
$ echo | gcc -m64 -E -P -dD - | grep LP
#define _LP64 1
#define __LP64__ 1
$ echo | gcc -mx32 -E -P -dD - | grep LP
#define _ILP32 1
#define __ILP32__ 1

Would a uint64_t be recommended in this case?

a uint64_t would fix it for x86_64, but break it most 32bit systems as sizeof(unsigned long) == 32bit for them

New changeset aa9cfeea07ad by Gregory P. Smith in branch '3.2':
Fixes issue #15000: support the odd x32 abi on posixsubprocess's system call.
http://hg.python.org/cpython/rev/aa9cfeea07ad

New changeset 5a4d5e714d08 by Gregory P. Smith in branch 'default':
Fixes issue #15000: support the odd x32 abi on posixsubprocess's system call.
http://hg.python.org/cpython/rev/5a4d5e714d08