Trying to build an app for updating android OS built from source. Even after signing the app with the platform key, the method RecoverySystem.installPackage(context,file) when applied on an updatefile placed in '/data/cache' gives error that writing to /cache is not permitted for the app. Also, an SElinux error is thrown for trying to access /cache partition.
The app holds the necessary permissions android.permission.RECOVERY, android.permission.REBOOT and android.permission.ACCESS_CACHE_FILESYSTEM
Going through the source code, the lines
...
FileWriter uncryptFile = new FileWriter(UNCRYPT_PACKAGE_FILE);
try {
uncryptFile.write(filename + "\n");
} finally {
uncryptFile.close();
}
...
in RecoverySystem.installPackage() triggers the error. (http://androidxref.com/9.0.0_r3/xref/frameworks/base/core/java/android/os/RecoverySystem.java#562)
Even though the error is displayed, the device still reboots to apply update but the recovery shows "no command" screen most probably as no commands are written to /cache/recovery
the OS build is user build and thus not rooted.
am i missing something? is there any other way for a platform signed app to install firmware updates for the user build?