[PATCH xserver] present: Handle event mask updates as specified

[Kenneth Graunke]

On Thursday, July 28, 2016 5:58:57 PM PDT Michel Dänzer wrote:
> From: Michel Dänzer <michel.daenzer at amd.com>
> 
> From the Present extension specification:
> 
>  If eventContext specifies an existing event context, then if
>  eventMask is empty, PresentSelectInput deletes the specified
>  context, otherwise the specified event context is changed to
>  select a different set of events.
> 
>  If eventContext is an unused XID, then if eventMask is empty
>  no operation is performed. Otherwise, a new event context is
>  created selecting the specified events.
> 
> Without this change, there's no way for a client to explicitly change
> or destroy an existing event mask entry. Trying to do so as specified
> above would actually result in a new entry being created with
> the mask value passed in.
> 
> While we're at it, fix a memory leak if AddResource fails.
> 
> Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>
> ---
>  present/present_event.c   | 22 ++++++++++++++++++++--
>  present/present_request.c |  2 --
>  2 files changed, 20 insertions(+), 4 deletions(-)
> 
> diff --git a/present/present_event.c b/present/present_event.c
> index c586c9a..05862ca 100644
> --- a/present/present_event.c
> +++ b/present/present_event.c
> @@ -209,7 +209,7 @@ int
>  present_select_input(ClientPtr client, XID eid, WindowPtr window, CARD32 mask)
>  {
>      present_window_priv_ptr window_priv = present_get_window_priv(window, mask != 0);
> -    present_event_ptr event;
> +    present_event_ptr event, next;
>  
>      if (!window_priv) {
>          if (mask)
> @@ -217,6 +217,22 @@ present_select_input(ClientPtr client, XID eid, WindowPtr window, CARD32 mask)
>          return Success;
>      }
>  
> +    for (event = window_priv->events; event; event = next) {
> +        next = event->next;
> +
> +        if (event->client == client && event->id == eid) {
> +            if (mask)
> +                event->mask = mask;
> +            else
> +                FreeResource(eid, RT_NONE);
> +
> +            return Success;
> +        }
> +    }
> +
> +    if (!mask)
> +        return Success;
> +
>      event = calloc (1, sizeof (present_event_rec));
>      if (!event)
>          return BadAlloc;
> @@ -229,8 +245,10 @@ present_select_input(ClientPtr client, XID eid, WindowPtr window, CARD32 mask)
>      event->next = window_priv->events;
>      window_priv->events = event;
>  
> -    if (!AddResource(event->id, present_event_type, (void *) event))
> +    if (!AddResource(event->id, present_event_type, (void *) event)) {
> +        free(event);
>          return BadAlloc;
> +    }
>  
>      return Success;
>  }
> diff --git a/present/present_request.c b/present/present_request.c
> index 35320b6..c7663fc 100644
> --- a/present/present_request.c
> +++ b/present/present_request.c
> @@ -184,8 +184,6 @@ proc_present_select_input (ClientPtr client)
>  
>      REQUEST_SIZE_MATCH(xPresentSelectInputReq);
>  
> -    LEGAL_NEW_RESOURCE(stuff->eid, client);
> -
>      rc = dixLookupWindow(&window, stuff->window, client, DixGetAttrAccess);
>      if (rc != Success)
>          return rc;
> 

Looks good to me, thanks for fixing this!

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
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