[Libguestfs] [PATCH 1/2] gobject: Allow RConstOptString to return an error

[Richard W.M. Jones]

On Thu, Jan 26, 2012 at 11:49:54AM +0000, Matthew Booth wrote:
> RConstOptString cannot return an error in the C api. This makes it a special
> case for the GObject api, as all other return types have a corresponding GError
> **err argument to return an error. This change removes this special case, and
> includes the possibility of an error return in the API. An error is indicated by
> setting *err to a non-NULL value.
> 
> This change is in preparation for adding a close api. An attempt to call any
> api, even RConstOptString, on a closed handle must return an error.
> ---
>  generator/generator_gobject.ml |   29 +++++++++++------------------
>  1 files changed, 11 insertions(+), 18 deletions(-)
> 
> diff --git a/generator/generator_gobject.ml b/generator/generator_gobject.ml
> index 4779f23..abc9062 100644
> --- a/generator/generator_gobject.ml
> +++ b/generator/generator_gobject.ml
> @@ -37,10 +37,6 @@ let camel_of_name flags name =
>          a ^ String.uppercase (Str.first_chars b 1) ^ Str.string_after b 1
>      ) "" (Str.split (regexp "_") name)
>  
> -let returns_error = function
> -  | RConstOptString _ -> false
> -  | _ -> true
> -
>  let generate_gobject_proto name ?(single_line = true)
>                                  (ret, args, optargs) flags =
>    let spacer = if single_line then " " else "\n" in
> @@ -109,7 +105,7 @@ let generate_gobject_proto name ?(single_line = true)
>    | _ -> ());
>    if List.exists (function Cancellable -> true | _ -> false) flags then
>      pr ", GCancellable *cancellable";
> -  if returns_error ret then pr ", GError **err";
> +  pr ", GError **err";
>    pr ")"
>  
>  let generate_gobject_header_static () =
> @@ -602,7 +598,7 @@ let generate_gobject_c_methods () =
>        let doc = String.concat "\n * " doc in
>        let camel_name = camel_of_name flags name in
>        let is_RBufferOut = match ret with RBufferOut _ -> true | _ -> false in
> -      let error_return = match ret with
> +      let gobject_error_return = match ret with
>        | RErr ->
>          "FALSE"
>        | RInt _ | RInt64 _ | RBool _ ->
> @@ -688,7 +684,7 @@ let generate_gobject_c_methods () =
>        if cancellable then (
>          pr "  /* Check we haven't already been cancelled */\n";
>          pr "  if (g_cancellable_set_error_if_cancelled (cancellable, err))\n";
> -        pr "    return %s;\n\n" error_return;
> +        pr "    return %s;\n\n" gobject_error_return;
>        );
>  
>        pr "  guestfs_h *g = session->priv->g;\n";
> @@ -780,19 +776,16 @@ let generate_gobject_c_methods () =
>  
>        (* Check return, throw error if necessary, marshall return value *)
>  
> -      if returns_error ret then (
> +      (match errcode_of_ret ret with
> +      | `CannotReturnError -> ()
> +      | _ ->
>          pr "  if (ret == %s) {\n"
> -          (match ret with
> -          | RErr | RInt _ | RInt64 _ | RBool _ ->
> -            "-1"
> -          | RConstString _ | RString _ | RStringList _ | RHashtable _
> -          | RBufferOut _ | RStruct _ | RStructList _ ->
> -            "NULL"
> -          | RConstOptString _ ->
> -            assert false;
> -          );
> +          (match errcode_of_ret ret with
> +          | `CannotReturnError -> assert false
> +          | `ErrorIsMinusOne -> "-1"
> +          | `ErrorIsNULL -> "NULL");
>          pr "    g_set_error_literal(err, GUESTFS_ERROR, 0, guestfs_last_error(g));\n";
> -        pr "    return %s;\n" error_return;
> +        pr "    return %s;\n" gobject_error_return;
>          pr "  }\n";
>        );
>        pr "\n";

ACK.

Rich.

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