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Linux/X11 Keyboard interceptor

Posted on 2004-04-11
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Last Modified: 2010-04-21
Hi,

for some twisted reason, i need to write a program that locks any input from keyboard/mouse for other than my application.
I already tried, with limited success, with SDL WM_GrabInput, but that does not grab key combinations like CTRL+ALT+BACKSPACE or CTRL+ALT+F2.

What i need is advice, and possibly C (im programming in FPC for this) code to accomplish a total lockout from the keyboard, in order to prevent X shutdown, or console switching.
I dont expect answers or comments like "use XDM" or "disable the TTYs and run in X runlevel", since that's not what im looking for (actually might be the worst case scenario if there's no other solution to my problem".

Thanks.
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Question by:KiCk
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8 Comments
 
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Expert Comment

by:Alf666
ID: 10804493
Get the source of the "xev" utility.

It's a small X11 utility that allows you to grab any X11 events (including key presses/releases).
It's a very old X11 stuff which is a perfect example of what you are trying to achieve. It uses native X11 calls.
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Expert Comment

by:Alf666
ID: 10804500
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Expert Comment

by:astrand
ID: 10893157
To prevent the Xserver from ending / switching to VTs on CTRL+ALT+BACKSPACE / CTRL+ALT+F2, you need to change you XF86Config. Activate options DontZoom and DontZap.
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Author Comment

by:KiCk
ID: 10907005
DontZap does not prevent console switching.
DontZoom prevents the user from switching screen resolution, which i actually need :)

As for xev, that captures the events from within the window, not from all windows.
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astrand earned 500 total points
ID: 10907454
> DontZap does not prevent console switching.0

Ah, sorry. DontVTSwitch is what you want in this case.

As for listen to all events, try the program ftp://ftp.lysator.liu.se/pub/misc/evcnt-1.0.tar.gz.
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by:Alf666
ID: 10908301
I know the xev does not get all events, but it's a good example of what can be done.
Based on that, you can do whatever you want.
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