gistfile1.txt

#!/usr/bin/env python

from ctypes import *

class struct_timespec(Structure):
    _fields_ = [('tv_sec', c_long), ('tv_nsec', c_long)]

class struct_stat64(Structure):
    _fields_ = [
        ('st_dev', c_int32),
        ('st_mode', c_uint16),
        ('st_nlink', c_uint16),
        ('st_ino', c_uint64),
        ('st_uid', c_uint32),
        ('st_gid', c_uint32), 
        ('st_rdev', c_int32),
        ('st_atimespec', struct_timespec),
        ('st_mtimespec', struct_timespec),
        ('st_ctimespec', struct_timespec),
        ('st_birthtimespec', struct_timespec),

        ('st_size', c_uint64),
        ('st_blocks', c_uint64),
        ('st_blksize', c_uint32), 
        ('st_flags', c_uint32),
        ('st_gen', c_uint32), 
        ('st_lspare', c_uint32),
        ('st_qspare', c_uint64 * 2)
    ]

libc = CDLL('/usr/lib/libc.dylib') # or /usr/lib/libc.dylib
stat64 = libc.stat64
stat64.argtypes = [c_char_p, POINTER(struct_stat64)]

def get_generation(path):
    buf = struct_stat64()
    rv = stat64(path, pointer(buf))
    if rv != 0:
        raise OSError("Couldn't stat file %r" % path)
    return buf.st_gen

print get_generation('test.txt')