Is there a way to get the Alarm Application
source code for customizing the existing default source code availble in Android 2.3
.
You can download whole android source tree including alarm app from here:
http://source.android.com/source/downloading.html
You can download the app from the Android github mirror.
https://github.com/android/platform_packages_apps_alarmclock
Or on the cyanogen mirror
https://github.com/CyanogenMod/android_packages_apps_DeskClock
And because, you are a nice guy, you are wondering: What is the license of that code?
Glad you asked, because according to the Android documentation and cyanogen's wikipedia page, it's the Apache Software License 2.0
And as we all know, the Apache license 2.0 is a nice license for the all hackers. Even those who intend to make a buck or two. (you little capitalist scoundrels)
Please note that, I didn't come up with that nice cheat sheet. Someone else did.
This is the version that's made and maintained by Google now in a move to keep the apps unbundled from the system so as to provide the apps and updates to everyone even if the OEMs don't provide system update.
Hence It's the one that's available from the Play store to download too. The one that's shared previously is the stock App which is quite old.
https://android.googlesource.com/platform/packages/apps/DeskClock/
As the site of the source may keep changing, best way for you to figure it out is by visiting Android Open Source Project (AOSP) page and searching for the URL of the code.
Cyanogenmod is dead. So, here's the latest Lineage DeskClock (Apache License 2.0) repository:
https://github.com/LineageOS/android_packages_apps_DeskClock