For the record, I have been (ab?)using the “c_char_p” type to get the address of immutable byte strings without copying memory:

>>> from ctypes import *
>>> data = b"123\x00abc"
>>> pubyte = cast(c_char_p(data), POINTER(c_ubyte))
>>> address = addressof(pubyte.contents)
>>> string_at(address, 7)
b'123\x00abc'
>>> # 2nd instance has same address, rather than memory copy:
... cast(c_char_p(data), c_void_p).value == address
True

In to the documentation, “c_char_p” is only defined for zero-terminated strings, but it seems to also work for strings with embedded zero bytes. However it does not work for “bytearray” objects (“from_buffer” should work instead), nor memory views.