Subject: Bug#516: [X2Go-Dev] Bug#516: Bug#516: X2go successfully connects to server, but no window is shown

From: Mihai Moldovan <[email-masked]>
Date: Sun, 15 Jun 2014 05:55:29 +0200

Hello Mike and Sebastien,

I hope I may answer.

* On 15.06.2014 12:48 am, Mike Gabriel wrote:
> Please use nx-libs from the nightly builds (or build it your self) and re-test with my fixes for the xtrans
code in NX/X11. (xtrans is responsible to set up listening sockets for the
X-Server as well as handle incoming connections).

I did. Built Fedora RPM packages for nx-libs based on today's git repo and
installed them.

> Another issue may well be: does your Fedora PPC64 system use poly-instatiated /tmp directories? If so, then you
want 3.5.0.25, as well.

No, the test system does not.

Still, the problem persists.

There's also not really any clue why this might be happening, either.

x2goserver's debug messages look all fine:

Jun 15 05:23:07 localhost /usr/bin/x2gostartagent: x2gostartagent called with
options: 800x600 wan 16m-png-9 unix-kde-depth_32 us query 0 R firefox
Jun 15 05:23:07 localhost /usr/bin/x2gosessionlimit[10364]: x2gosessionlimit has
been called
Jun 15 05:23:07 localhost /usr/bin/x2golistsessions[10367]: x2golistsessions has
been called with options: --all-servers
Jun 15 05:23:10 localhost /usr/bin/x2gofeature: x2gofeature called with options:
X2GO_RUN_EXTENSIONS
Jun 15 05:23:11 localhost
/usr/share/x2go/x2gofeature.d/x2goserver-extensions.features:
x2goserver-extensions.features called with options: X2GO_RUN_EXTENSIONS
Jun 15 05:23:11 localhost /usr/bin/x2goserver-run-extensions:
x2goserver-run-extensions called with options:
root-93-1402802588_stRfirefox_dp32 pre-start
Jun 15 05:23:11 localhost /usr/bin/x2gostartagent: successfully started X2Go
agent session with ID root-93-1402802588_stRfirefox_dp32
Jun 15 05:23:11 localhost /usr/bin/x2gofeature: x2gofeature called with options:
X2GO_RUN_EXTENSIONS
Jun 15 05:23:11 localhost
/usr/share/x2go/x2gofeature.d/x2goserver-extensions.features:
x2goserver-extensions.features called with options: X2GO_RUN_EXTENSIONS
Jun 15 05:23:11 localhost /usr/bin/x2goserver-run-extensions:
x2goserver-run-extensions called with options:
root-93-1402802588_stRfirefox_dp32 post-start
Jun 15 05:23:11 localhost /usr/bin/x2gostartagent: blocking creation of agent's
keyboard file /root/.x2go/C-root-93-1402802588_stRfirefox_dp32/keyboard as
requested by session startup command
Jun 15 05:23:16 localhost /usr/bin/x2goruncommand: x2goruncommand called with
options: 93 10575 root-93-1402802588_stRfirefox_dp32 30136 /usr/bin/firefox nosnd R
Jun 15 05:23:16 localhost /usr/bin/x2gofeature: x2gofeature called with options:
X2GO_RUN_EXTENSIONS
Jun 15 05:23:16 localhost
/usr/share/x2go/x2gofeature.d/x2goserver-extensions.features:
x2goserver-extensions.features called with options: X2GO_RUN_EXTENSIONS
Jun 15 05:23:16 localhost /usr/bin/x2goserver-run-extensions:
x2goserver-run-extensions called with options:
root-93-1402802588_stRfirefox_dp32 pre-runcommand
Jun 15 05:23:16 localhost /usr/bin/x2gomountdirs[10764]: x2gomountdirs has been
called with options: dir root-93-1402802588_stRfirefox_dp32 ionic
/root/.x2go/ssh/key.J82727
/Users/ionic/.x2go/S-root-93-1402802588_stRfirefox_dp32/spool__PRINT_SPOOL___REVERSESSH_PORT__30137
Jun 15 05:23:16 localhost /usr/bin/x2gosetkeyboard: x2gosetkeyboard called with
options:
Jun 15 05:23:16 localhost /usr/bin/x2gofeature: x2gofeature called with options:
X2GO_XSESSION
Jun 15 05:23:16 localhost /usr/bin/x2gosetkeyboard:
/root/.x2go/C-root-93-1402802588_stRfirefox_dp32/keyboard is blocked, not
setting keyboard parameters from client-side settings
Jun 15 05:23:16 localhost
/usr/share/x2go/x2gofeature.d/x2goserver-extensions.features:
x2goserver-extensions.features called with options: X2GO_XSESSION
Jun 15 05:23:16 localhost /usr/share/x2go/x2gofeature.d/x2goserver.features:
x2goserver.features called with options: X2GO_XSESSION
Jun 15 05:23:16 localhost
/usr/share/x2go/x2gofeature.d/x2goserver-fmbindings.features:
x2goserver-fmbindings.features called with options: X2GO_XSESSION
Jun 15 05:23:16 localhost
/usr/share/x2go/x2gofeature.d/x2goserver-xsession.features:
x2goserver-xsession.features called with options: X2GO_XSESSION
Jun 15 05:23:17 localhost /usr/bin/x2gomountdirs[10764]: successfully mounted
[email-masked]:30137/Users/ionic/.x2go/S-root-93-1402802588_stRfirefox_dp32/spool
to /tmp/.x2go-root/spool/C-root-93-1402802588_stRfirefox_dp32

But there is one interesting bit in the C-... directory.

The "clients" contains those lines:

error opening security policy file /usr/lib64/nx/X11/xserver/SecurityPolicy
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Error:            Can't find file "null" for symbols include
>                   Exiting
>                   Abandoning symbols file "default"
> Error:            Cannot open "compiled/server-93.xkm" to write keyboard
description
>                   Exiting

We can ignore the first one.

This, however, leaves us with the xkbcomp errors.

I tried "debugging" that and /usr/bin/xkbcomp has indeed been called with "-w 1
-R/usr/share/X11/xkb -xkm - -em1 'The XKEYBOARD keymap compiler (xkbcomp)
reports:' -emp '>'  -eml 'Errors from xkbcomp are not fatal to the X server'
compiled/server-93.xkm"

Now, while normally xkbcomp errors may not be fatal to the X server, they could
be fatal to x2go. Is that true?

I can get rid of the first error ('Can't find file "null"') by forcing a
specific keyboard layout in x2goclient.

Further, I'm wondering why xkbcomp is called with "compiled/server-93.xkm" as
its output argument. To my understanding, xkbcomp should rather upload its
compiled xkbmap to the Xserver on display 93 (note that the value is within the
output file name) instead of writing it to a file. Am I mistaken?

Unfortunately, I have been unable to reproduce this on any of my other two
machines. I tried everything, from setting a specific keyboard value to sending
null/null as on the ppc64 machine, but my x86_64 machines never even called xkbcomp.

I've had a quick look at nx-libs sources and grepped for xkbcomp, but this
string is all over the place in the X11 sources, so getting some useful
information extracted is difficult.

Do YOU know, by any chance, when xkbcomp is supposed to be called?
As none of my machines are doing that, I suppose xkbcomp is not supposed to be
called at all?

I'll try to get a closer look at that later today, those were my initial findings.

Any input is appreciated.

Mihai