Re: [gdm-list] Changing the login screen
- From: Brian Cameron <Brian Cameron Sun COM>
- To: Akash Gangil <akashg1611 gmail com>
- Cc: gdm-list gnome org
- Subject: Re: [gdm-list] Changing the login screen
- Date: Thu, 11 Feb 2010 11:36:50 -0600
Akash:
I wanted to know as to where username , password label(s) and
text-box(es) are created . I mean the GUI formation of the login window .
The GDM login GUI creates labels to place prompts and messages. The
actual prompts (e.g. "Username:", "Password:") and the messages (e.g.
"Incorrect password", etc.) all are provided to GDM from the PAM
modules. GDM just blindly places the prompts and labels into the
areas of the GUI that are defined by the GDM login GUI.
In the new GDM (version 2.21 and later), the text fields are specified
in the /usr/share/gdm/gdm-greeter-login-window.ui or
/usr/share/gdm/gdm-greeter-login-window.xml file. These can be edited
by glade-3. The PAM entry field is the field with the name
"auth-prompt-entry", the PAM message field is "auth-message-label"
and the prompt is "auth-prompt-label". These names are defined in the
gdm-greeter-login-window.ui or gdm-greeter-login-window.xml file.
In the old GDM (2.20 and earlier), you can refer to the gui/gdmlogin.c
file (for the gdmlogin GUI program) or gui/greeter/greeter.c file (for
the gdmgreeter GUI program) and the function process_operation manages
the setting of the label. You can refer to daemon/verify-pam.c file to
see how messages get sent from PAM to the GUI using GDM_MSG,
GDM_PROMPT, GDM_NOECHO, etc.
Note that PAM can be configured differently on each distro. You can
refer to the pam.conf or pam.d m anpage on your system to learn about
how PAM works and is configured.
By default, GDM uses the "gdm" PAM stack. So whatever PAM modules
are defined in the "gdm" PAM stack will be used when GDM is running.
This should be specified in your /etc/pam.conf or /etc/pam.d PAM
configuration file. You will need to look at the source code for the
PAM modules you are using on your system to see the actual label
text that is shown to the user.
Note that this mailing list is more about GDM than PAM, and if you
need help working with PAM modules, then there are better PAM
specific forums where you would likely find better assistance.
Brian
On Wed, Feb 10, 2010 at 5:26 PM, Rohan Anil <rohan anil gmail com
<mailto:rohan anil gmail com>> wrote:
Isn't username and password asked by the pam module ?
i guess look at pam_unix2.c
On Wed, Feb 10, 2010 at 4:44 PM, Akash Gangil <akashg1611 gmail com
<mailto:akashg1611 gmail com>> wrote:
Hi
I was searching through the code where username and password are
asked from the user. And
I found that that gdm takes some of the screen labels that we
see during login from an xml file.
gdm-greeter-login-window.ui , here I found
"Log In"
"Computer Name"
"Cancel"
and all other label butting , but couldn't find those of
username and password .
Where are they?
On Tue, Feb 9, 2010 at 8:58 PM, Brian Cameron
<Brian Cameron sun com <mailto:Brian Cameron sun com>> wrote:
Akash:
But what should I do know as my ubuntu just hangs during
booting ,
should I reinstall?
I am running Ubuntu 9.10 on Vmplayer.
Re-installing will likely get your system working again.
However, if
you plan on doing development work with GDM, then it might
be worthwhile
for you to investigate the problem, and try to debug and fix it.
One unfortunate reality about doing development work on GDM
is that
it can be more difficult than working on most other
programs. Since
GDM is the first GUI program that runs on the system, it is not
uncommon to debug problems with it starting up.
Debugging programs that are run in a normal user session is
easier
since you can have multiple terminal windows open and you
can easily
run the debugger and an application in separate windows.
However, to
do this with GDM, you often need to debug from the system
console or
use ssh or telnet from a second machine to attach to running GDM
processes. So, doing GDM development is more cumbersome.
So, in short, it will likely be difficult for you to do much
development work on GDM if you do not learn how to debug and
fix these
sorts of problems.
Brian
On Tue, Feb 9, 2010 at 5:33 AM, Brian Cameron
<Brian Cameron sun com <mailto:Brian Cameron sun com>
<mailto:Brian Cameron sun com
<mailto:Brian Cameron sun com>>> wrote:
Akash:
Thanks for replying back .
One more thing , I installed the gdm from source
(./configure ,
make ,
make install).
But now when I restart it just shows a blank
screen after ubuntu
logo
(Ubuntu 9.10) .
Is it because I didn't uninstall the previous
version of gdm before
installing from source ?
It is hard to say. In general, it is probably best
to uninstall the
previous version of GDM before installing a new version.
Each distro has its own unique configuration for
modules like GDM, so
problems could be related to how GDM was configured,
or how your distro
integrates with GDM. For example, if the system
assumes that GDM is
installed to a particular file location, you may
have problems if you
have installed it to a different place. Also, each
distro may apply
distro-specific patches to GDM, and it may not work
without applying
such patches. If you find it is not working, then
it might be a good
idea to check with your distro and make sure that
you apply any patches
needed for GDM to operate well on your platform.
You could try editing your /etc/gdm/custom.conf file
so it contains
these lines:
[debug]
Enable=true
This will cause GDM to append debug messages to your
syslog (the
/var/log/messages file )Then cause GDM to fail
again. After it fails,
you can check the gdm-related messages at the bottom
of the syslog
file and see if it helps you understand why it might
be failing.
You can share such debug output with us on this
mailing list, and
we can help analyze the debug output if it isn't
clear what the
problem is.
Brian
On Tue, Feb 9, 2010 at 2:03 AM, Brian Cameron
<Brian Cameron sun com <mailto:Brian Cameron sun com>
<mailto:Brian Cameron sun com
<mailto:Brian Cameron sun com>>
<mailto:Brian Cameron sun com
<mailto:Brian Cameron sun com>
<mailto:Brian Cameron sun com
<mailto:Brian Cameron sun com>>>>
wrote:
Akash:
I was just browsing through the code of
GDM . What I
want to do is ,
take the username and password from the
user in a gtk window
(like the
explorer one ) instead of the usual
login procedure. So
I was
searching
through the code as to where can I do
this , but am lost
with
the code ,
can anybody help me with that ?
GDM makes use of PAM for authentication.
GDM just blindly
displays
whatever prompts (username/password/etc.)
that PAM is
configured to
display. You should be able to refer to the
pam.d or
pam.conf manpage
for more information.
If you wish to modify how GDM prompts the
user, this would
require
either configuring PAM differently, or
modifying GDM to not
use PAM.
Note that you could probably find more
PAM-focused forums
where you
would likely find better help with PAM
specific questions
than on this
mailing list.
Brian
--
Best Regards
Akash Gangil
--
Best Regards
Akash Gangil
--
Best Regards
Akash Gangil
_______________________________________________
gdm-list mailing list
gdm-list gnome org <mailto:gdm-list gnome org>
http://mail.gnome.org/mailman/listinfo/gdm-list
--
Rohan Anil
IVth Year Information Systems
BITS Pilani Goa Campus
--
Best Regards
Akash Gangil
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