Get filesystem ID from device node

fs_uuid_devnode.py

import ctypes

lib = ctypes.CDLL('libblkid.so')

lib.blkid_new_probe_from_filename.argtypes = (ctypes.c_char_p,)
lib.blkid_new_probe_from_filename.restype = ctypes.c_void_p

lib.blkid_free_probe.argtypes = (ctypes.c_void_p,)

lib.blkid_do_probe.argtypes = (ctypes.c_void_p,)
lib.blkid_do_probe.restype = ctypes.c_int

lib.blkid_probe_lookup_value.argtypes = (ctypes.c_void_p, ctypes.c_char_p, ctypes.POINTER(ctypes.c_char_p), ctypes.POINTER(ctypes.c_size_t))
lib.blkid_probe_lookup_value.restype = ctypes.c_int

lib.blkid_probe_numof_values.argtypes = (ctypes.c_void_p,)
lib.blkid_probe_numof_values.restype = ctypes.c_int


def get_fs_uuid(dev_name):
	probe = lib.blkid_new_probe_from_filename(bytes(dev_name, 'ascii'))
	assert probe
	done = False
	found_uuid = None
	while True:
		state = lib.blkid_do_probe(probe)
		if state == 0:
			UUID_len = ctypes.c_size_t()
			UUID = ctypes.c_char_p()
			res = lib.blkid_probe_lookup_value(probe, b'UUID', ctypes.byref(UUID), ctypes.byref(UUID_len))
			if res == 0 and UUID_len.value:
				found_uuid = UUID.value[:UUID_len.value]
				break	#We are done so no reason to keep probing

		elif state == -1:
			raise Exception('Failure happened!')
			break
		elif state == 1:
			done = True
			break
		else:
			raise Exception('Unexpected state')
			break

	lib.blkid_free_probe(probe)
	return found_uuid


#print(get_fs_uuid('/dev/sdd1'))
#b'1234-ABCD'