[PATCH v3] client: extend error handling
Marek Chalupa
mchqwerty at gmail.com
Wed May 7 07:18:34 PDT 2014
On 5 May 2014 15:02, Pekka Paalanen <ppaalanen at gmail.com> wrote:
> On Wed, 30 Apr 2014 10:11:01 +0200
> Marek Chalupa <mchqwerty at gmail.com> wrote:
>
> > When an error occurs, wl_display_get_error() does not
> > provide any way of getting know if it was a local error or if it was
> > an error event, respectively what object caused the error and what
> > the error was.
> >
> > This patch introduces a new function wl_display_get_protocol_error()
> > which will return error code, interface and id of the object that
> > generated the error.
> > wl_display_get_error() will work the same way as before.
> >
> > wl_display_get_protocol_error() DOES NOT indicate that a non-protocol
> > error happened. It returns valid information only in that case that
> > (protocol) error occurred, so it should be used after calling
> > wl_display_get_error() with positive result.
> >
> > Thanks to Pekka Paalanen <ppaalanen at gmail.com> for pointing out
> > issues in the first versions of this patch.
> > ---
> > src/wayland-client.c | 138
> ++++++++++++++++++++++++++++++++++++++++++++-------
> > src/wayland-client.h | 3 ++
> > 2 files changed, 123 insertions(+), 18 deletions(-)
> >
> > diff --git a/src/wayland-client.c b/src/wayland-client.c
> > index bd40313..8dd8804 100644
> > --- a/src/wayland-client.c
> > +++ b/src/wayland-client.c
> > @@ -78,7 +78,24 @@ struct wl_event_queue {
> > struct wl_display {
> > struct wl_proxy proxy;
> > struct wl_connection *connection;
> > +
> > + /* errno of the last wl_display error */
> > int last_error;
> > +
> > + /* When display gets an error event from some object, it stores
> > + * information about it here, so that client can get this
> > + * information afterwards */
> > + struct {
> > + /* Code of the error. It can be compared to
> > + * the interface's errors enumeration. */
> > + int code;
>
> I just checked in wl_display::error specification, and the type of the
> error code is uint32_t.
>
> > + /* interface (protocol) in which the error occurred */
> > + const struct wl_interface *interface;
> > + /* id of the proxy that caused the error. There's no
> warranty
> > + * that the proxy is still valid. It's up to client how it
> will
> > + * use it */
> > + uint32_t id;
> > + } protocol_error;
> > int fd;
> > pthread_t display_thread;
> > struct wl_map objects;
> > @@ -96,6 +113,14 @@ struct wl_display {
> >
> > static int debug_client = 0;
> >
> > +/**
> > + * This function is called for local errors (no memory, server hung up)
> > + *
> > + * \param display
> > + * \param error error value (EINVAL, EFAULT, ...)
> > + *
> > + * \note this function is called with display mutex locked
> > + */
> > static void
> > display_fatal_error(struct wl_display *display, int error)
> > {
> > @@ -105,7 +130,7 @@ display_fatal_error(struct wl_display *display, int
> error)
> > return;
> >
> > if (!error)
> > - error = 1;
> > + error = EFAULT;
> >
> > display->last_error = error;
> >
> > @@ -113,11 +138,56 @@ display_fatal_error(struct wl_display *display,
> int error)
> > pthread_cond_broadcast(&iter->cond);
> > }
> >
> > +/**
> > + * This function is called for error events
> > + * and idicates that in some object occured an error.
> > + * Difference between this function and display_fatal_error()
> > + * is that this one handles errors that will come in wire, whereas
> > + * display_fatal_error() is called for local errors.
> > + *
> > + * \param display
> > + * \param code error code
> > + * \param id id of the object that generated the error
> > + * \param intf protocol interface
> > + */
> > static void
> > -wl_display_fatal_error(struct wl_display *display, int error)
> > +display_protocol_error(struct wl_display *display, int code,
> > + unsigned int id, const struct wl_interface *intf)
> > {
> > + struct wl_event_queue *iter;
> > + int err;
> > +
> > + if (display->last_error)
> > + return;
> > +
> > + /* set correct errno */
> > + if (wl_interface_equal(intf, &wl_display_interface)) {
> > + switch (code) {
> > + case WL_DISPLAY_ERROR_INVALID_OBJECT:
> > + case WL_DISPLAY_ERROR_INVALID_METHOD:
> > + err = EINVAL;
> > + break;
> > + case WL_DISPLAY_ERROR_NO_MEMORY:
> > + err = ENOMEM;
> > + break;
> > + default:
> > + err = EFAULT;
> > + }
> > + } else {
> > + err = EPROTO;
> > + }
> > +
> > pthread_mutex_lock(&display->mutex);
> > - display_fatal_error(display, error);
> > +
> > + display->last_error = err;
> > +
> > + display->protocol_error.code = code;
> > + display->protocol_error.id = id;
> > + display->protocol_error.interface = intf;
> > +
> > + wl_list_for_each(iter, &display->event_queue_list, link)
> > + pthread_cond_broadcast(&iter->cond);
> > +
> > pthread_mutex_unlock(&display->mutex);
> > }
> >
> > @@ -579,25 +649,12 @@ display_handle_error(void *data,
> > uint32_t code, const char *message)
> > {
> > struct wl_proxy *proxy = object;
> > - int err;
> >
> > wl_log("%s@%u: error %d: %s\n",
> > proxy->object.interface->name, proxy->object.id, code,
> message);
> >
> > - switch (code) {
> > - case WL_DISPLAY_ERROR_INVALID_OBJECT:
> > - case WL_DISPLAY_ERROR_INVALID_METHOD:
> > - err = EINVAL;
> > - break;
> > - case WL_DISPLAY_ERROR_NO_MEMORY:
> > - err = ENOMEM;
> > - break;
> > - default:
> > - err = EFAULT;
> > - break;
> > - }
> > -
> > - wl_display_fatal_error(display, err);
> > + display_protocol_error(display, code, proxy->object.id,
> > + proxy->object.interface);
> > }
> >
> > static void
> > @@ -1489,6 +1546,51 @@ wl_display_get_error(struct wl_display *display)
> > return ret;
> > }
> >
> > +/**
> > + * Retrieve the information about a protocol error
> > + *
> > + * \param display display
> > + * \param interface if not NULL, store there an interface on which the
> error
> > + * occured
> > + * \param id if not NULL, store there the id of the object that
> generated
> > + * the error. There's no warranty that the object is
> still valid.
> > + * Client must know if he deleted the object or not.
> > + * \return The error code as defined in the interface
> specification.
> > + *
> > + * \code
> > + * int err = wl_display_get_error(display);
> > + *
> > + * if (err == EPROTO) {
> > + * code = wl_display_get_protocol_error(display, &interface,
> &id);
> > + * handle_error(code, interface, id);
> > + * }
> > + *
> > + * ...
> > + *
> > + * \endcode
> > + */
> > +WL_EXPORT int
>
> Needs to be uint32_t.
>
> > +wl_display_get_protocol_error(struct wl_display *display,
> > + const struct wl_interface **interface,
> > + uint32_t *id)
> > +{
> > + int ret;
> > +
> > + pthread_mutex_lock(&display->mutex);
> > +
> > + ret = display->protocol_error.code;
> > +
> > + if (interface)
> > + *interface = display->protocol_error.interface;
> > + if (id)
> > + *id = display->protocol_error.id;
> > +
> > + pthread_mutex_unlock(&display->mutex);
> > +
> > + return ret;
> > +}
> > +
> > +
> > /** Send all buffered requests on the display to the server
> > *
> > * \param display The display context object
> > diff --git a/src/wayland-client.h b/src/wayland-client.h
> > index 2a32785..99fac06 100644
> > --- a/src/wayland-client.h
> > +++ b/src/wayland-client.h
> > @@ -161,6 +161,9 @@ int wl_display_dispatch_queue_pending(struct
> wl_display *display,
> > struct wl_event_queue *queue);
> > int wl_display_dispatch_pending(struct wl_display *display);
> > int wl_display_get_error(struct wl_display *display);
> > +int wl_display_get_protocol_error(struct wl_display *display,
>
> uint32_t.
>
> > + const struct wl_interface **interface,
> > + uint32_t *id);
> >
> > int wl_display_flush(struct wl_display *display);
> > int wl_display_roundtrip(struct wl_display *display);
>
> Hi,
>
> sorry for not noticing earlier that the wl_display::error event's code
> is uint32_t.
Well, I should have checked that. Thanks :)
> With that fixed, this patch is
> Reviewed-by: Pekka Paalanen <ppaalanen at gmail.com>
>
> The next step would be to add a test in libwayland to excercise this. I
> took a quick look but I'm not sure which one would be the best example
> to derive from.
>
>
> Thanks,
> pq
>
New (and hopefully the last) version of the patch is cooming.
Thanks,
Marek
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