Some Python ctypes-based POSIX shared memory functions

shm.py

import os
import sys

try:
    from _posixshmem import shm_open, shm_unlink
except ImportError:
    import ctypes

    dllname = None
    if sys.platform.startswith("linux"):
        dllname = "librt.so"
    rtld = ctypes.CDLL(dllname, use_errno=True)

    def shm_open(name, flags, mode):
        if isinstance(name, str):
            name = name.encode()
        buf = ctypes.create_string_buffer(name)

        result = rtld.shm_open(buf, ctypes.c_int(flags), ctypes.c_ushort(mode))

        if result == -1:
            errno = ctypes.get_errno()
            raise OSError(errno, os.strerror(errno), name.decode())

        return result

    def shm_unlink(name):
        if isinstance(name, str):
            name = name.encode()
        buf = ctypes.create_string_buffer(name)

        result = rtld.shm_unlink(buf)

        if result == -1:
            errno = ctypes.get_errno()
            raise OSError(errno, os.strerror(errno), name.decode())


def main():
    name = "/myshm"
    f = shm_open(name, flags=os.O_RDWR | os.O_CREAT | os.O_EXCL, mode=0o666)
    print(f, name)
    shm_unlink(name)


if __name__ == "__main__":
    main()