Question

I have code

system("reboot") 

The reboot command works in the terminal, but even if I run the app as root, the operation is still denied. Has anyone found any way that works, or can explain a bit about SBSetting’s reboot, which makes me curious?

Answer 1

I figured out a way to do it, although it’s a bit convoluted. The problem is that even if you setup your app to run as root, when you make system() calls, you’re apparently still limited to user mobile privileges. Since mobile cannot call reboot (successfully), this doesn’t work.

The way I got around this problem is to take advantage of a new feature that SBSettings supports. SBSettings has a privileged daemon process that runs. It allows you to plug in your own commands, by simply writing a script (or other executable) and dumping it in the appropriate directory (/var/mobile/Library/SBSettings/Commands). Once you then restart the sbsettingsd process, you can get it to run your script by posting a notification. If you name your script

com.mycompany.reboot

then from within your app, you can execute this code:

#import <notify.h>

notify_post("com.mycompany.reboot");

Then, you make com.mycompany.reboot a simple shell script like this:

#!/bin/sh
reboot

And make sure to chmod 755 on your com.mycompany.reboot script. The full details of this SBSettings command feature can be found here:

http://thebigboss.org/guides/sbsettings-toggle-spec (see Calling External Functions and Scripts …)

Anyway, it does require your app to depend on SBSettings, but it’s a free app, and most users would probably want to have it anyway. For now, it accomplishes the goal of rebooting (or anything else that requires root access) programmatically, via notify_post().