Running SVGA and GL games from X
The GLX Quakeworld and Quake II clients are native X applications, but since they use Mesa rather than the
3Dfx mini−driver, they're slower than the lib3dfxgl.so versions. For this reason, you may still favor this
way of starting games from X over using the GLX clients.
This is based on a Linux Gazette 2 Cent Tip by Joey Hess ( joey@kite.ml.org) The original is at
http://www.ssc.com/lg/issue20/lg_tips20.html#squake
Yes, it's possible to run the Quake games from X if you're root, but such behavior is naughty, and you still
run the risk of having Quake crash and leave the console unresponsive. With a little work you can make it
possible for a regular user to run SVGA and GL Quake from X AND automatically switch back to X when
the program is finished, regardless of whether it exited normally or not.
Note: when I say "Quake" in the text below, I really mean "quake, glquake squake, qwcl, glqwcl, qwcl.x11 or
quake2".
First, you'll need the open(1) package by Jon Tombs. This is a set of two very small programs that
allow you to switch between virtual consoles and start programs on them. Download open from
http://sunsite.unc.edu/pub/Linux/utils/console/. You shouldn't have to do much more than
make;make install to compile and install it. Once it's installed, you need to make the
open and switchto executables setuid root. So do this:
cd /usr/local/bin
chown root open switchto
chmod 4755 open switchto
•
Linux Quake HOWTO
6.1 Running X and GL games without setuid 41
Next, save the following code to a file called getvc.c: •
/* getvc.c
* Prints the number of the current VC to stdout. Most of this code
* was ripped from the open program, and this code is GPL'd
*
* Joey Hess, Fri Apr 4 14:58:50 EST 1997
*/
#include
#include
main () {
int fd = 0;
struct vt_stat vt;
if ((fd = open("/dev/console",O_WRONLY,0)) < 0) {
perror("Failed to open /dev/console\n");
return(2);
}
if (ioctl(fd, VT_GETSTATE, &vt) < 0) {
perror("can't get VTstate\n");
close(fd);
return(4);
}
printf("%d\n",vt.v_active);
}
/* End of getvc.c */
Compile it and install it somewhere in your $PATH:
gcc getvc.c −o getvc
strip getvc
mv getvc /usr/local/bin
Now create a script called runvc: your $PATH: •
#!/bin/sh
# Run something on a VC, from X, and switch back to X when done.
# GPL Joey Hess, Thu, 10 Jul 1997 23:27:08 −0400
exec open −s −− sh −c "$* ; chvt `getvc`"
Make it executable and put it somewhere in your $PATH:
chmod 755 runvc
mv runvc /usr/local/bin
Now you can use the runvc command to start Quake. Continue to use whatever command line you
usually use to start your game, but put runvc at the beginning:
Linux Quake HOWTO
6.1 Running X and GL games without setuid 42
runvc ./quake2 +set vid_ref gl +connect quake.foo.com
You'll automatically switch to a VC, run Quake and then switch back to X when it's done!
Update: Joey Hess wrote in to say:
I'd like to point out that some people may find that this doesn't work. If your
/dev/ttyxx devices do not let you write to them by default (a good idea), then the
open command won't be able to switch to them. In that case, you need to chown the
next tty that is free after you start up X. I do this in xdm's Xtartup_0 script, as
follows:
# Set up tty8 as a console that is writable by the current user, so
# open −s commands can be used to run stuff there.
# Tty8 is used becuase it's the next free tty after 7 where X runs,
# and so open tries to use it.
chmod 640 /dev/tty8
chown $USER.root /dev/tty8
# This does open up a tiny security hole:
# user_a logs in with xdm, then logs out.
# user_b logs in at console.
# user_a can now redirect user_b to tty9 via the open command,
# and plop them down into some program that, perhaps, tries to
# persuade them to enter their password.
3Dfx mini−driver, they're slower than the lib3dfxgl.so versions. For this reason, you may still favor this
way of starting games from X over using the GLX clients.
This is based on a Linux Gazette 2 Cent Tip by Joey Hess ( joey@kite.ml.org) The original is at
http://www.ssc.com/lg/issue20/lg_tips20.html#squake
Yes, it's possible to run the Quake games from X if you're root, but such behavior is naughty, and you still
run the risk of having Quake crash and leave the console unresponsive. With a little work you can make it
possible for a regular user to run SVGA and GL Quake from X AND automatically switch back to X when
the program is finished, regardless of whether it exited normally or not.
Note: when I say "Quake" in the text below, I really mean "quake, glquake squake, qwcl, glqwcl, qwcl.x11 or
quake2".
First, you'll need the open(1) package by Jon Tombs. This is a set of two very small programs that
allow you to switch between virtual consoles and start programs on them. Download open from
http://sunsite.unc.edu/pub/Linux/utils/console/. You shouldn't have to do much more than
make;make install to compile and install it. Once it's installed, you need to make the
open and switchto executables setuid root. So do this:
cd /usr/local/bin
chown root open switchto
chmod 4755 open switchto
•
Linux Quake HOWTO
6.1 Running X and GL games without setuid 41
Next, save the following code to a file called getvc.c: •
/* getvc.c
* Prints the number of the current VC to stdout. Most of this code
* was ripped from the open program, and this code is GPL'd
*
* Joey Hess, Fri Apr 4 14:58:50 EST 1997
*/
#include
#include
main () {
int fd = 0;
struct vt_stat vt;
if ((fd = open("/dev/console",O_WRONLY,0)) < 0) {
perror("Failed to open /dev/console\n");
return(2);
}
if (ioctl(fd, VT_GETSTATE, &vt) < 0) {
perror("can't get VTstate\n");
close(fd);
return(4);
}
printf("%d\n",vt.v_active);
}
/* End of getvc.c */
Compile it and install it somewhere in your $PATH:
gcc getvc.c −o getvc
strip getvc
mv getvc /usr/local/bin
Now create a script called runvc: your $PATH: •
#!/bin/sh
# Run something on a VC, from X, and switch back to X when done.
# GPL Joey Hess, Thu, 10 Jul 1997 23:27:08 −0400
exec open −s −− sh −c "$* ; chvt `getvc`"
Make it executable and put it somewhere in your $PATH:
chmod 755 runvc
mv runvc /usr/local/bin
Now you can use the runvc command to start Quake. Continue to use whatever command line you
usually use to start your game, but put runvc at the beginning:
Linux Quake HOWTO
6.1 Running X and GL games without setuid 42
runvc ./quake2 +set vid_ref gl +connect quake.foo.com
You'll automatically switch to a VC, run Quake and then switch back to X when it's done!
Update: Joey Hess wrote in to say:
I'd like to point out that some people may find that this doesn't work. If your
/dev/ttyxx devices do not let you write to them by default (a good idea), then the
open command won't be able to switch to them. In that case, you need to chown the
next tty that is free after you start up X. I do this in xdm's Xtartup_0 script, as
follows:
# Set up tty8 as a console that is writable by the current user, so
# open −s commands can be used to run stuff there.
# Tty8 is used becuase it's the next free tty after 7 where X runs,
# and so open tries to use it.
chmod 640 /dev/tty8
chown $USER.root /dev/tty8
# This does open up a tiny security hole:
# user_a logs in with xdm, then logs out.
# user_b logs in at console.
# user_a can now redirect user_b to tty9 via the open command,
# and plop them down into some program that, perhaps, tries to
# persuade them to enter their password.
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