make sure that a crashing module can't lead to a reboot-loop

[ms2-fixes] / MS2Debounce / src / de / rmdir / ms2debounce / DebounceModuleHelper.java

package de.rmdir.ms2debounce;

import java.io.InputStream;
import java.io.OutputStream;
import java.io.File;
import java.io.FileReader;
import java.io.BufferedReader;

import android.content.Context;
import android.content.SharedPreferences;

public class DebounceModuleHelper
{
	private Context ctx;
	public static final String PREFS_NAME = "DebounceCfg";

	public DebounceModuleHelper(Context context) {
		ctx = context;
	}

	public void loadModule() {
		SharedPreferences settings = ctx.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);

		int delay = settings.getInt("debounce_delay", 10);
		loadModule(delay);
	}

	public synchronized void loadModule(int delay) {
		File debounce_ko = new File(ctx.getFilesDir() + "/debounce.ko");

		extractModule();

		SharedPreferences settings = ctx.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
		SharedPreferences.Editor editor = settings.edit();
		if (is_safe_to_load()) {
			editor.putBoolean("safe_to_load", false);
			editor.commit();
		}

		try {
			Process insmod = Runtime.getRuntime().exec(new String[]{"su","-c","/system/bin/insmod " + debounce_ko + " debounce_delay=" + delay});
			insmod.waitFor();
		} catch (Exception e) {
			return;
		}
	
		if (getDelay() <= 0) {
			return;
		}

		/* Module was obviously loaded, so it is safe to load on boot */
		editor.putBoolean("safe_to_load", true);
		editor.commit();
	}

	public synchronized void unloadModule() {
		try {
			Process rmmod = Runtime.getRuntime().exec(new String[]{"su","-c","/system/bin/rmmod debounce"});
			rmmod.waitFor();
		} catch (Exception e) {}
	}

	public synchronized boolean isLoaded() {
		boolean loaded = false;
		try {
			String read;

			FileReader modules = new FileReader("/proc/modules");
			BufferedReader modules_buf = new BufferedReader(modules);

			while((read = modules_buf.readLine()) != null) {
				if (read.regionMatches(0, "debounce", 0, 8)) {
					loaded = true;
				}
			}

		} catch (Exception e) {
			loaded = false;
		}

		return loaded;
	}

	public synchronized int getDelay() {
		int debounce_delay = -1;

		try {
			String read;

			FileReader delay = new FileReader("/sys/module/debounce/parameters/debounce_delay");
			BufferedReader delay_buf = new BufferedReader(delay);

			read = delay_buf.readLine();
			if (read != null) {
				debounce_delay = Integer.parseInt(read.trim());
			}
		} catch (Exception e) {}

		return debounce_delay;
	}

	public synchronized boolean is_safe_to_load() {
		SharedPreferences settings = ctx.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
		boolean safe_to_load = settings.getBoolean("safe_to_load", false);

		return safe_to_load;
	}

	private synchronized void extractModule() {
		File debounce_ko = new File(ctx.getFilesDir() + "/debounce.ko");

		if (debounce_ko.exists()) {
			return;
		}

		try {
			InputStream apk = ctx.getAssets().open("debounce.ko");
			OutputStream mod = ctx.openFileOutput("debounce.ko.tmp", 0);

			//I assume a page is 4k...
			byte buf[] = new byte[4096];
			int bytes;

			while((bytes = apk.read(buf)) != -1) {
				mod.write(buf, 0, bytes);
			}

			apk.close();
			mod.close();

			File tmpfile = new File(debounce_ko + ".tmp");
			tmpfile.renameTo(debounce_ko);
		} catch (Exception e) {}
	}
}