Clipboard interaction issues - breaks after awhile

Jon TURNEY jon.turney@dronecode.org.uk
Tue Oct 7 13:14:00 GMT 2014


On 03/10/2014 21:02, mathog wrote:
> Today I ran into an interesting variant of this.
>
> 1.  putty   ssh -X session from XP to a remote Centos 6.5 system.
> 2.  on the remote system: xterm &
> 3.  copy a line of text on remote system
> 4.  paste it into a roundcube "compose" window on XP system.  The
> browser is Seamonkey 2.29.
>
> It works fine for a while and then the _browser_ locks.  It is
> definitely an X11
> issue because this unlocked the browser: exit all xterms, exit the putty
> session, kill
> the X11 server.  The browser didn't unlock until the last step.
>
> This lock up happened twice within half an hour.  Now I can't reproduce it.

There is supposed to be a 1 second timeout to ensure that we always 
respond to the Windows application in a timely fashion.

(The issue here is that Windows clipboard pastes are synchronous (when 
the Windows application calls GetClipboardData(), it sends a 
WM_RENDERFORMAT to the clipboard owner, and blocks until that returns), 
but the X11 clipboard render is asynchronous (since we send a 
XConvertSelection() request to the clipboard owner and wait for a 
SelectionNotify event))

I've looked at this code again, and can't see anything wrong with they 
way this timeout is implemented.

So, I'm afraid there's not a lot I can do without a repeatable 
reproduction or a log file.

> That is the only system I have used recently that uses xterm instead of
> uxterm.
>
> The clipboard problems I have seen previously were all in the other
> direction, where clip going into an X11 application would fail.
>
> Unfortunately I didn't save the X server log file.  Which, brings up
> another point.
> The X11 server is started by clicking on "start_server.bat" which contains:
>
> @echo off
> set CYGXTOP=%~dp0
> C:
> chdir "%CYGXTOP%\bin"
> start Xwin :0 -multiwindow
>
> It always overwrites the Xwin.0.log file when it starts.  Is there some
> change we could make to this .bat script that would cause it to at least
> save one previous version?

I guess you could add to the above something like:

move C:\cygwin\var\log\XWin.0.log C:\cygwin\var\log\XWin.0.log.old

but yes, there is actually some code in the server to do that, but it's 
not turned on in XWin for unknown reasons...

-- 
Jon TURNEY
Volunteer Cygwin/X X Server maintainer

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