Bug 13652 – REGRESSION: WebCore::DragController crashes if WebDragSourceActionDHTML cleared

• Component: New Bugs
• Status: RESOLVED FIXED

[Justin Bur]

If webView:dragSourceActionMaskForPoint: (WebUIDelegate protocol) is implemented and returns a mask in which the WebDragSourceActionDHTML bit is clear, dragging does not work when dragging ordinary text, links, etc. from that WebView.
- If another WebView in the same app (without this bit cleared) has already performed a successful drag, then the pasteboard will contain that previous drag's data.
- If no other WebView has already performed a successful drag operation, then DragController crashes, with a trashed stack.

To reproduce, simply implement the following in a WebUIDelegate:

- (unsigned)webView:(WebView *)sender dragSourceActionMaskForPoint:(NSPoint)point
{
	return (WebDragSourceActionAny & ~WebDragSourceActionDHTML);
}

Bug does not occur in WebKit released with OS X 10.4 Tiger. I don't know at what point it turned up in the nightlies. It is present in rev. 21322 of 2007-05-09.

[Oliver Hunt]

<rdar://problem/5335265> 

Reproduced by bludgeoning WebDragClient
WebCore::DragSourceAction WebDragClient::dragSourceActionMaskForPoint(const IntPoint& windowPoint)
{
    return (DragSourceAction)(WebDragSourceActionAny & ~WebDragSourceActionDHTML);/*
    NSPoint viewPoint = [m_webView convertPoint:windowPoint fromView:nil];
    return (DragSourceAction)[[m_webView _UIDelegateForwarder] webView:m_webView dragSourceActionMaskForPoint:viewPoint];*/
}

We end up with a null clipboard, which is worrisome...

[Oliver Hunt]

Created attachment 15510 [details]
Fix non-dhtml dragging

Righto, the problem was that we didn't preflight the clipboard unless we thought we might be performing a dhtml drag, which is an entirely unnecessary (and incorrect) requirement.

[Oliver Hunt]

Landed in r24283