[Git][wxwidgets/wxwidgets][master] 2 commits: Guard against re-entering in wxOSX wxDropSource::DoDragDrop()

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Vadim Zeitlin (@_VZ_)

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Dec 13, 2025, 7:37:15 PM (3 days ago) Dec 13
to wx-commi...@googlegroups.com

Vadim Zeitlin pushed to branch master at wxWidgets / wxWidgets

Commits:

  • 948b4f36
    by 徐扬斌 at 2025-12-14T00:56:41+01:00 
    Guard against re-entering in wxOSX wxDropSource::DoDragDrop()

At least when using CEF, repeatedly starting drag-and-drop operation may
result in stack overflow.

Messages processed by CEF are handled when wxEVT_IDLE is triggered and
the problematic scenario is when:

1. Cocoa calls OSXDefaultModeObserverCallBack()
2. wxEVT_IDLE is triggered.
3. wxWebViewChromium::OnIdle() is called.
4. CefDoMessageLoopWork() performs various jobs for CEF.

If DoDragDrop() is invoked during CefDoMessageLoopWork(), and there is a
recursive call to it, then the previous DoDragDrop() can't return
anymore, and will, in turn, prevent CefDoMessageLoopWork() from
returning to the caller.

Prevent recursively re-entering this function to avoid this.

See #24520.

Co-authored-by: Vadim Zeitlin <va...@wxwidgets.org>
  • 31966f7d
    by 徐扬斌 at 2025-12-14T01:03:27+01:00 
    Allow wxDropSource::DoDragDrop() without mouse event in wxOSX

DoDragDrop() may be called not only in response to a mouse event, but
also, when using CEF, from external code.

Synthesize an artificial event in this case instead of failing with an
assert.

See #24520.

1 changed file:

Changes:

  • src/osx/cocoa/dnd.mm
    ... ... @@ -18,6 +18,7 @@
    18 18 
     #include "wx/dnd.h"
    19 19 
     #include "wx/clipbrd.h"
    20 20 
     #include "wx/filename.h"
    21 
    +#include "wx/recguard.h"
    21 22
    22 23 
     #ifndef WX_PRECOMP
    23 24 
         #include "wx/app.h"
    ... ... @@ -483,17 +484,39 @@ typedef NSString* NSPasteboardType;
    483 484
    484 485 
     wxDragResult wxDropSource::DoDragDrop(int flags)
    485 486 
     {
    487 
    +    static wxRecursionGuardFlag s_inDragDrop = 0;
    488 
    +
    486 489 
         wxASSERT_MSG( m_data, wxT("Drop source: no data") );
    487 490
    488 491 
         wxDragResult result = wxDragNone;
    489 492 
         if ((m_data == nullptr) || (m_data->GetFormatCount() == 0))
    490 493 
             return result;
    491 494
    495 
    +    wxRecursionGuard guard(s_inDragDrop);
    496 
    +    if (guard.IsInside())
    497 
    +        return wxDragNone;
    498 
    +
    492 499 
         NSView* view = m_window->GetPeer()->GetWXWidget();
    493 500 
         if (view)
    494 501 
         {
    495 502 
             NSEvent* theEvent = (NSEvent*)wxTheApp->MacGetCurrentEvent();
    496 
    -        wxASSERT_MSG(theEvent, "DoDragDrop must be called in response to a mouse down or drag event.");
    503 
    +
    504 
    +        // Drag and drop operation can be started from an external mouse event
    505 
    +        // handler, this happens at least when using CEF, so synthesize the
    506 
    +        // mouse event if we don't have one.
    507 
    +        if (theEvent == nil)
    508 
    +        {
    509 
    +            NSPoint mouse_location = [NSEvent mouseLocation];
    510 
    +            theEvent = [NSEvent mouseEventWithType:NSEventTypeLeftMouseDragged
    511 
    +                location:mouse_location
    512 
    +                modifierFlags:0
    513 
    +                timestamp: 0
    514 
    +                windowNumber: [NSWindow windowNumberAtPoint:mouse_location belowWindowWithWindowNumber:0]
    515 
    +                context:nil
    516 
    +                eventNumber: 0
    517 
    +                clickCount: 0
    518 
    +                pressure: 1.0];
    519 
    +        }
    497 520
    498 521 
             gCurrentSource = this;
    499 522
    ... ... @@ -560,7 +583,6 @@ wxDragResult wxDropSource::DoDragDrop(int flags)
    560 583 
             gCurrentSource = nullptr;
    561 584 
         }
    562 585
    563 
    -
    564 586 
         return result;
    565 587 
     }
    566 588

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