cvsroot is a script to help keep track of multiple sites when using CVS, and in particular the CVSROOT and CVS_RSH environment variables for those sites. It creates a $HOME/.cvsroot file, with shortcut names representing the different CVS sites. The new environment variables appropriate to the site selected will then be set, and a new shell will be spawned to keep the variables. In this way, you do not have to keep setting the environment yourself, and can rely on the script to keep track of things for you.
The LibXDiff library implements basic and yet complete functionalities to create file differences/patches to both binary and text files. It uses memory files as file abstraction to achieve both performance and portability. For binary files, it implements both (with some modification) the algorithm described in "File System Support for Delta Compression" by Joshua P. MacDonald and the algorithm described in "Fingerprinting By Random Polynomials" by Michael O. Rabin. For text files, it follows directives described in "An O(ND) Difference Algorithm and Its Variations" by Eugene W. Myers. Memory files used by the library are basically a collection of buffers that store the file content.