I found myself needing a program to apply binary patches in the IPS file format and I was really disappointed that there are no proper Unix programs for that purpose available. So I set out to make my own, but instead of just applying patches it would be a complete suite of tools to handle all IPS-related tasks.
IPS-Tools is the result, it consists of three standalone CLI programs, one CLI program that acts as an entry point to the suite, and a C library for inclusion in other applications. There are three programs because I have identified three problem domains: applying a patch, generating a patch and examining a patch.
The tools are all written in C99 using only the standard library, they are tiny and should run on pretty much anything. Great for embedding in other applications. In fact, I have a GUI frontend that uses the library to give users a drag & drop interface, but it still needs some more polish before I can release it.
I also took the opportunity to write a complete specification of the IPS file format, because all I was able to find have been bits and pieces everywhere and only closed-source programs, so I had to piece things together. IPS is a fairly simple format, but it has some hairy corners because over time people have added extensions to it (compressed records and truncation). With IPS-tools there is a complete file specification and a reference implementation freely available to the public.