Incorrect Cygwin/X behavior leads to .X0-lock related fatal error

[Jon TURNEY]

On 12/03/2010 02:31, Ken Klein wrote:
> Here is tool behavior that seems like a bug in 1.7.1 related to the
> Cygwin/X FAQ item 3.4 (A2)called "Fatal server error: Can't read lock file
> /tmp/.X0-lock."  I am posting this, because the faq item states that the
> buggy behavior happens "For reasons which are not well understood at
> present."  This post presents what I consider to be incorrect behavior that
> leads to this error.
>
> If I log on as a user without admin rights (on Windows XP), and I start
> Cygwin/X using the XWin Server program shortcut, the referenced lock file
> gets created and gives me read/write access.  The Everyone user just has
> read access.  When I then close my XWin session, the lock file remains.  I
> log out of Windows, then someone else logs on (also without admin rights),
> and they get the fatal error as described in the FAQ item, since they do
> not have write access to the lock file.
>
> If, however, I had originally started Cygwin/X by opening a Cygwin window
> then entering startx, when I eventually end my Cygwin session, the lock
> file gets deleted.  So in this scenario, the next person to log on will not
> get the fatal error, since Cygwin didn't leave the lock file behind.
>
> My opinion is that the startx scenario behaves correctly, and the XWin
> Server shortcut scenario presents a bug, namely, it leaves behind the lock
> file after the session is ended.

Thanks for the detailed bug report.

In fact that FAQ is slightly out of date and we do now understand that the 
problem is shown when running XWin as both Administrator and non-Adminstrator 
users as you describe.

I'm not able to reproduce the difference in behaviour you describe (of leaving 
the log file behind) between running startx (which then starts XWin) and 
directly starting XWin when running as a non-administrator user.

Can you be specific about how you are exiting XWin which causes it to leave 
the lock file behind?  This shouldn't happen, and is the cause of the problem.

-- 
Jon TURNEY
Volunteer Cygwin/X X Server maintainer

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