testcase.py

import mmap
import cffi

ffi = cffi.FFI()

ffi.cdef("struct test { int x; };")

ref = None

def alloc():
    global ref

    mem = mmap.mmap(-1, 0x1000, mmap.MAP_SHARED, mmap.PROT_READ | mmap.PROT_WRITE)

    # Uncomment this to keep mem alive
    #ref = mem

    return ffi.cast("struct test *", ffi.from_buffer(mem))

def main():
    test = alloc()
    print(test.x)

if __name__ == "__main__":
    main()