On Sun, Jan 8, 2017 at 8:25 AM, Armin Rigo <[email protected]> wrote:
>
> c_raw = ctypes.PYFUNCTYPE(ctypes.c_void_p, ctypes.c_void_p)(lambda p: p)
Use ctypes.addressof.
> addr = c_raw(ctypes.pointer(T.from_buffer(m)))
> b = ctypes.cast(addr, ctypes.POINTER(T)).contents
ctypes.cast uses an FFI call. In this case you can more simply use from_address:
b = T.from_address(ctypes.addressof(T.from_buffer(m)))
There's no supporting connection between b and m. If m was allocated
from a heap/pool/freelist, as opposed to a separate mmap
(VirtualAlloc) call, then you won't necessarily get a segfault (access
violation) if b is used after m has been deallocated or internally
realloc'd. It can lead to corrupt data and difficult to diagnose
errors. You're lucky if it segfaults.
_______________________________________________
Python-Dev mailing list
[email protected]
https://mail.python.org/mailman/listinfo/python-dev
Unsubscribe:
https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
