pwrsurge

An nl-based power manager

The power manager that allows you to drive the process

This power manager does very little heavy lifting. It simply subscribes to the ACPI event family in netlink and calls out to the library that you specify from the command line to execute callbacks.

Hrm?

For examples of prototypes of callbacks in Rust and C, see the example_libs/ directory. The callbacks must have the function prototypes in the examples specified for both languages to have any guarantee of working. Otherwise, you are in uncharted waters and the behavior is undefined. The device_class field of ACPI events should be the name of the function which you wish to be executed on the event. Examples are battery, cpu, etc and running it without these defined will print debugging information to the console so you can implement them and know what events are happening which you might want to define behavior for.

Usage

Running pwrsurge PATH_TO_SHARED_LIBRARY will allow you to specify the compiled libary object containing the callbacks which you wish to be executed. If no arguments are specified, it will default to /etc/pwrsurge/libevents.so. Please read the next section for security considerations.

Security - how is this okay?

This power manager might leave you thinking "how on earth is this okay?". That's a good question. There are ways of using it that are decidedly not okay. One is running this as root and specifying a library that is in a non-root user writable directory. There is a potential race condition in which the user with write access can swap out the library you've specified with something that should not have root access. If you are not running this as root, this is somewhat less of a concern as the power manager will not execute the code as root. This will resolve the privilege escalation concern. However, best practice on single user systems is to make /etc/pwrsurge/libevents.so world-readable and writable only by root.

TD;DR Never ever ever run this program as root unless the library you are pointing to and the directory that contains it is not writable by any user other than root. Even better, make /etc/pwrsurge/libevents.so readable by all and writable only by root.