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hw/xwin: Fix clipboard thread restart

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It seems that the clipboard thread restart mechanism has been broken for a
while, which can be demonstrated using XDMCP with KDM (e.g. to a Kubutunu 12.04
host)

KDM kills all attached clients, including the clipboard integration client,
which restarts, but then exits on WM_QUIT.

Using PostQuitMessage() in WM_DESTROY is unhelpful, as we may not actually be
quitting the thread, if we just destroyed the window because the clipboard
thread is about to retry, because he WM_QUIT message sticks around, and is
noticed the next time we look at the window message queue and confuses us into
thinking we need to quit.

Sending a WM_DESTROY is apparently never correct anyhow, see [1]

So:

1/ Use DestroyWindow() to destroy the clipboard messaging window when cleaning
up for retry or exit in winClipboardProc (the clipboard thread main proc)

2/ Send a special WM_WM_QUIT message in winClipboardWindowDestroy() from the X
server thread when the X server is resetting.

3/ When processing that WM_WM_QUIT message in the clipboard thread, cause the
clipboard window to PostQuitMessage(), which causes the clipboard thread to
exit.

[1] http://blogs.msdn.com/b/oldnewthing/archive/2011/09/26/10216420.aspx

Signed-off-by: Jon TURNEY <jon.turney@dronecode.org.uk>
Reviewed-by: Colin Harrison <colin.harrison@virgin.net>
This commit is contained in:
Jon TURNEY 2014-02-21 23:20:00 +00:00
parent b4a08e642b
commit 94d433c8cb
3 changed files with 9 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
hw/xwin/winclipboard/internal.h
View File

@ -44,6 +44,7 @@
#define WIN_XEVENTS_NOTIFY_TARGETS 4
#define WM_WM_REINIT (WM_USER + 1)
#define WM_WM_QUIT (WM_USER + 2)
/*
* References to external symbols

4
hw/xwin/winclipboard/thread.c
View File

@ -351,7 +351,7 @@ winClipboardProc(Bool fUseUnicode, char *szDisplay)
winClipboardProc_Done:
/* Close our Windows window */
if (g_hwndClipboard) {
winClipboardWindowDestroy();
DestroyWindow(g_hwndClipboard);
}
/* Close our X window */
@ -491,7 +491,7 @@ void
winClipboardWindowDestroy(void)
{
if (g_hwndClipboard) {
SendMessage(g_hwndClipboard, WM_DESTROY, 0, 0);
SendMessage(g_hwndClipboard, WM_WM_QUIT, 0, 0);
}
}

6
hw/xwin/winclipboard/wndproc.c
View File

@ -154,6 +154,12 @@ winClipboardWindowProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
ChangeClipboardChain(hwnd, s_hwndNextViewer);
s_hwndNextViewer = NULL;
}
return 0;
case WM_WM_QUIT:
{
winDebug("winClipboardWindowProc - WM_WM_QUIT\n");
PostQuitMessage(0);
}