RFR: 8275033: Drag and drop a file produces NullPointerException Cannot read field "dragboard"

[Kevin Rushforth]

On Fri, 20 Jan 2023 20:35:07 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

>> When running on Wayland the `GDK_DRAG_LEAVE` is sent just after `GDK_DROP_START`. The leave event causes java to set `dragGesture` to `null`. On Xorg this event is not sent. 
>> 
>> The fix just ignores the leave event if a drop occurred.
>
> modules/javafx.graphics/src/main/native-glass/gtk/glass_dnd.cpp line 141:
> 
>> 139:     jobjectArray mimes;
>> 140:     gint dx, dy;
>> 141: } enter_ctx = {NULL, FALSE, FALSE, NULL, 0, 0};
> 
> it's funny how it's initialized here and also in reset_enter_ctx(), and just by coincidence both produce the same result.  This will break if initial values are other than NULL, 0, FALSE.

Indeed. During my review, before I looked more closely, I was all ready to post a comment to the effect that it was never set back to FALSE. Then I saw the `memset` in `reset_enter_ctx` that you referred to. Not the way I would have initially designed it -- relying on '0' being the desired default value for all fields (including pointers) -- but given that it is that way, this doesn't make the problem any worse.

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PR: https://git.openjdk.org/jfx/pull/1005