kernel patch for "Can't open display" - also fixes CVS problem The descriptor is a file, not a socket
Thu Jun 21 12:06:00 GMT 2001
Mark, thanks very much, it works fine, I think that patch needs to get
into the main cygwin tree asap, as you have also fixed all my problems
with cvs under cygwin on WinME. Thanks again. There are a lot of posts
for the past few versions of Cygwin regarding the CVS problem, hence the
cross-post and full quote of your message.
To all that receive the "Can't open display" message for your X clients.
If this is not related to the DISPLAY variable, and other obvious
problems, then this kernel patch may help you. I just hacked this
together last night, so YMMV, but for the brave you can download a new
cygwin1.dll from my site at:
Copy this cygwin1.dll into /bin for the latest release of cygwin. It
works for me, but no assurances about your results. Here is a
description of the problem. This description pertains to the
winsup/cygwin portion of the cygwin kernel.
Inside of the client code for X applications, you will find a fcntl
F_SETFD. By default the fhandle_socket.cc file for the kernel passes
this to fhandle.cc. Inside of fhandle.cc the F_SETFD gets passed to
"set_close_on_exec(...)". This then calls set_inheritence(..), which
this ominous line in it:
/* FIXME: This won't work with sockets */
Anyway, needless to say, the problem has to do with the duplicate handle
not being valid for subsequent socket calls.
A "fix" that I implemented is to disable the close_on_exec support for
sockets only. Inside of fhandler_socket.cc , edit the fcntl(..)
and add this to the switch statement:
// the default handler is broken for now
// should send -1 but have to lie to vtwm so send 0
res = 0;
After I did this, X starts up great and everything is fine except I miss
my KDE ;-)
Of course, your mileage may vary, and I advise that this bug be sent to
the real developers of the cygwin kernel so they can fix it properly.
This should be considered a temporary work around!
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