PhysicsFS is a library to provide abstract access to various archives.
It is intended for use in video games, and the design was somewhat
inspired by Quake 3's file subsystem. The programmer defines a "write
directory" on the physical filesystem. No file writing done through the
PhysicsFS API can leave that write directory, for security. For
example, an embedded scripting language cannot write outside of this
path if it uses PhysFS for all of its I/O, which means that untrusted
scripts can run more safely. Symbolic links can be disabled as well,
for added safety. For file reading, the programmer lists directories
and archives that form a "search path". Once the search path is
defined, it becomes a single, transparent hierarchical filesystem. This
makes for easy access to ZIP files in the same way as you access a file
directly on the disk, and it makes it easy to ship a new archive that
will override a previous archive on a per-file basis. Finally,
PhysicsFS gives you platform-abstracted means to determine if CD-ROMs
are available, the user's home directory, where in the real filesystem
your program is running, etc.