Re: [RFC v5 080/126] QAPI: introduce ERRP_AUTO_PROPAGATE

[Eric Blake]

On 10/11/19 11:05 AM, Vladimir Sementsov-Ogievskiy wrote:
> If we want to add some info to errp (by error_prepend() or
> error_append_hint()), we must use the ERRP_AUTO_PROPAGATE macro.
> Otherwise, this info will not be added when errp == &fatal_err
> (the program will exit prior to the error_append_hint() or
> error_prepend() call).  Fix such cases.
>
> If we want to check error after errp-function call, we need to
> introduce local_err and than propagate it to errp. Instead, use
> ERRP_AUTO_PROPAGATE macro, benefits are:
> 1. No need of explicit error_propagate call
> 2. No need of explicit local_err variable: use errp directly
> 3. ERRP_AUTO_PROPAGATE leaves errp as is if it's not NULL or
>     &error_fatel, this means that we don't break error_abort
>     (we'll abort on error_set, not on error_propagate)

> Reported-by: Kevin Wolf <address@hidden>
> Reported-by: Greg Kurz <address@hidden>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> ---
>   qapi/qapi-visit-core.c      | 56 ++++++++++++++++---------------------
>   qapi/qmp-dispatch.c         |  7 ++---
>   qapi/string-input-visitor.c |  7 ++---
>   3 files changed, 30 insertions(+), 40 deletions(-)

> +++ b/qapi/qmp-dispatch.c
> @@ -78,7 +78,7 @@ static QDict *qmp_dispatch_check_obj(const QObject *request, 
> bool allow_oob,
>   static QObject *do_qmp_dispatch(QmpCommandList *cmds, QObject *request,
>                                   bool allow_oob, Error **errp)
>   {
> -    Error *local_err = NULL;
> +    ERRP_AUTO_PROPAGATE();
>       bool oob;
>       const char *command;
>       QDict *args, *dict;
> @@ -129,9 +129,8 @@ static QObject *do_qmp_dispatch(QmpCommandList *cmds, 
> QObject *request,
>           qobject_ref(args);
>       }
>   
> -    cmd->fn(args, &ret, &local_err);
> -    if (local_err) {
> -        error_propagate(errp, local_err);
> +    cmd->fn(args, &ret, errp);
> +    if (*errp) {
>       } else if (cmd->options & QCO_NO_SUCCESS_RESP) {

Looks a bit funny with the empty if clause, but not worth changing.

>           g_assert(!ret);
>       } else if (!ret) {

Reviewed-by: Eric Blake <address@hidden>

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
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