/CyLogos

Logos syntax for Cycript

Primary LanguagePython

CyLogos

A preprocessor + loader that allows use of Logos syntax with Cycript. Simply drop .cy files in /Library/CyLogos/Tweaks to have them automatically preprocessed and loaded into SpringBoard. Only %hook, %end, and %orig are supported currently.

Check out Cycript.org and the iPhone Dev Wiki Logos page for more information on Cycript and Logos.

Example

Example file before preprocessing (based on this cycript demo):

%hook NSObject

function description() {
	return %orig + " (of doom)";
}

%end

Preprocessed:

var oldm = {};
MS.hookMessage(NSObject, @selector(description), function() {
    return oldm->call(this) + " (of doom)";
}, oldm)

How to use (specifics)

There are a few basic assumptions for syntax:

  1. Each %hook and %end directive is on a line by itself.
  2. Function names within %hook blocks match the objective-C selector that they want to hook.

This means that to hook SBApplicationController's method - (void)_sendInstalledAppsDidChangeNotification:(id)arg1 removed:(id)arg2 modified:(id)arg3, you would write the following script:

%hook SBApplicationController

function _sendInstalledAppsDidChangeNotification:removed:modified:(arg1, arg2, arg3) {
  //Do stuff here
  %orig;
}

%end

To load the above script, install the loader tweak, save the script as a .cy file in /Library/CyLogos/Tweaks and run killall SpringBoard on your device.

The syntax rules are pretty much the same as the actual Logos (no %hook nesting, %orig can be called with or without arguments, etc.). It's good practice to end each statement with a semicolon even though Cycript doesn't require it because it can sometimes mess up the Cycript parser if they're left out.

FAQ

What can I use this for?

This could be helpful for tweak developers to quickly prototype tweaks or for beginners to learn Logos syntax.

How do I use it?

Write a tweak in cycript + logos syntax, drop it in /Library/CyLogos/Tweaks with the loader tweak installed, restart SpringBoard, and watch the system log for preprocessor or Cycript errors. See the examples folder for a few example tweaks (tested on iOS 6).

When will ____ be supported?

It depends. Some things like C function hooking are on the to-do list (see To do.txt), but others like support for hooking daemons aren't. For use cases beyond basic tweaks or for more powerful objective-C features you should use Theos.

Why is the preprocessor written in Python/why is ____ kind of hacky?

A lot of this is kind of experimental/just me trying things out. Python is easy for prototyping and it conveniently runs on jailbroken iOS. I'll probably change the language used eventually. If you have a better way to do something, let me know!