[Libguestfs] [libnbd PATCH v2 5/8] python: Make py_aio_buffer a private struct

[Richard W.M. Jones]

On Mon, Jun 06, 2022 at 09:08:30PM -0500, Eric Blake wrote:
> Instead of having methods.c poking into the internals of a struct that
> we defined, have it use PyMemoryView* and Py_buffer*; this separation
> makes it easier to separate how we store the persistent data (for now,
> in a PyCapsule) from how we access the data.  Eventually, the use of
> PyMemoryView* will make it easier for future patches to get rid of
> some layers of copying.  nbd_internal_py_init_aio_buffer() is new; for
> now it doesn't fail, but it can in a future patch.
> 
> For now, we still have to hang on to a python reference to the
> PyCapsule object holding our malloc'd C pointer, and since the
> MemoryView we just created is not backed by a Python object, we must
> ensure we don't leak it to Python code.  But this will change in an
> upcoming patch.
> 
[...]
> @@ -477,13 +481,8 @@ let
>    (* Second pass, and call the underlying C function. *)
>    List.iter (
>      function
> -    | BytesPersistIn (n, _) ->
> -       pr "  if (!%s_buf->initialized) {\n" n;
> -       pr "    memset (%s_buf->data, 0, %s_buf->len);\n" n n;
> -       pr "    %s_buf->initialized = true;\n" n;
> -       pr "  }\n"
>      | BytesPersistOut (n, _) ->
> -       pr "  %s_buf->initialized = true;\n" n
> +       pr "  if (nbd_internal_py_init_aio_buffer (%s) < 0) goto out;\n" n

Can't fail, but that was noted in the commit message so that's OK.

Reviewed-by: Richard W.M. Jones <rjones at redhat.com>

Rich.

-- 
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