Please, do consider writing the C book as well. Most publishers have beta programs these days (O'Reilly, Manning, Pragmatic Programmers). Don't leave it in a desk drawer (so to speak).
Perhaps simplified Redis example could work as a good base to learn C. Single threaded, memory only persistence, network communication service so no complex stuff like concurrency and file management. Though there's probably a lot more going on in there...
Perhaps "Redis for devops" is another book waiting to happen, or how to write Redis modules. By the way, Manning's book (from 2013) is freely available these days:
https://redislabs.com/resources/ebook/
Perhaps simplified Redis example could work as a good base to learn C. Single threaded, memory only persistence, network communication service so no complex stuff like concurrency and file management. Though there's probably a lot more going on in there...
Perhaps "Redis for devops" is another book waiting to happen, or how to write Redis modules. By the way, Manning's book (from 2013) is freely available these days: https://redislabs.com/resources/ebook/