[Libguestfs] [PATCH libnbd 5/6] generator: Implement OClosure.

[Eric Blake]

On 8/13/19 5:06 AM, Richard W.M. Jones wrote:
> An optional Closure parameter, but otherwise works the same way as
> Closure.

> @@ -3778,6 +3777,7 @@ let generate_lib_api_c () =
>      ) args;
>      List.iter (
>        function
> +      | OClosure { cbname } -> pr ", %s_callback ? \"<fun>\" : \"NULL\"" cbname

Well, it also permits a NULL fn pointer.

> @@ -4383,6 +4387,16 @@ let print_python_binding name { args; optargs; ret; may_set_error } =
>    ) args;
>    List.iter (
>      function
> +    | OClosure { cbname } ->
> +       pr "  if (%s_user_data) {\n" cbname;
> +       pr "    /* Increment refcount since pointer may be saved by libnbd. */\n";
> +       pr "    Py_INCREF (%s_user_data);\n" cbname;
> +       pr "    if (!PyCallable_Check (%s_user_data)) {\n" cbname;

I don't think PyNone is callable; this probably needs to gain a special
case for when the user omitted the optional argument and we thus...

> +       pr "      PyErr_SetString (PyExc_TypeError,\n";
> +       pr "                       \"callback parameter %s is not callable\");\n" cbname;
> +       pr "      return NULL;\n";
> +       pr "    }\n";
> +       pr "  }\n"
>      | OFlags (n, _) -> pr "  %s_u32 = %s;\n" n n
>    ) optargs;
>  
> @@ -4412,6 +4426,9 @@ let print_python_binding name { args; optargs; ret; may_set_error } =
>    ) args;
>    List.iter (
>      function
> +    | OClosure { cbname } ->
> +       pr ", %s_user_data ? %s_wrapper : NULL" cbname cbname;
> +       pr ", %s_user_data" cbname
>      | OFlags (n, _) -> pr ", %s_u32" n
>    ) optargs;
>    pr ");\n";
> @@ -4668,6 +4685,7 @@ class NBD (object):
>        let optargs =
>          List.map (
>            function
> +          | OClosure { cbname } -> cbname, Some "None", None

...passed in the default Python 'None' in its place.


> @@ -5202,6 +5223,19 @@ let print_ocaml_binding (name, { args; optargs; ret }) =
>  
>    List.iter (
>      function
> +    | OClosure { cbname } ->
> +       pr "  const void *%s_callback = NULL;\n" cbname;
> +       pr "  value *%s_user_data = NULL;\n" cbname;
> +       pr "  if (%sv != Val_int (0)) { /* Some closure */\n" cbname;

But for OCaml you got it right - you are handling 'None' vs. 'Some closure'.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

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