Didj Replacement App Menu

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NOTE

This is not a working replacement yet, is considered a work-in-progress, is currently musings on how it could be done, and is in general not going to work for you. Proceed with extreme caution!

Theoretical implementation

Background info

GrizzlyAdams on the IRC channel has been working on implementing a new menu system called DJ System Menu.[1] With that in mind, he is currently working on having a way to launch the menu from Brio. This most likely won't work well for a few reasons. First, if it's launched directly from Brio's AppManager, AppManager stays in memory, eating away at what precious RAM we have to work with. Secondly, if it's launched, and AppManager is exited to save RAM, the Didj by default will shutdown because of how /usr/bin/launch_main behaves (which is pretty much the state machine watching AppManager and reacting to it's various exit states.)

Basic idea

Now, in order to work around the issues I think the best idea would be to stop Brio from launching AppManager to begin with. The most user friendly way I can think of is how GrizzlyAdams kind of started, but rather than launching djsm from AppManager, the small Brio app disables Brio and enables djsm to start when the system is started.

Basic implementation

This is the actual application which Brio will launch:

/*
 * Simple Brio App.so to remove Brio at startup.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#define LaunchPath "/Didj/disabler"
#define LaunchBin "/Didj/disable/disable.sh"

int CreateApp(int argc, char** argv)
{
	chdir(LaunchPath);

	system("/bin/sh " LaunchBin);

	return 0;
}

And this is the /Didj/disable/disable.sh shell script:

#/bin/sh
# make sure our / is mounted read/write
mount -o remount,rw /
# remove Brio from launching
rm -fr /etc/rc.d/*lightning
# remove an example init.d script that's pointless
rm -fr /etc/rc.d/*example
# copy our init.d script over
cp djsm.init.d /etc/init.d/djsm
# make a link that tell it when it should launch
ln -s /etc/init.d/djsm /etc/rc.d/S99djsm
# and make the link to tell it when it should quit
ln -s /etc/init.d/djsm /etc/rc.d/K99djsm

And here would be the djsm.init.d:

#!/bin/sh
DJSMPWD=/Didj/djsm
case "$1" in
	start)
		echo "Starting djsm"
		$DJSMPWD/djsm -pid $DJSMPWD/djsm.pid
		;;

	stop)
		echo "Stopping djsm"
		kill `cat $DJSMPWD/djsm.pid`
		;;
	*)
		echo "Usage: /etc/init.d/example {start|stop}"
		exit 1
		;;
esac

exit 0

Now, these are just untested prototypes at this point to get the basic idea across about one possible method for disabling Brio from Brio.

references

  1. http://didj.twihb.net/djsm/