Libeio is a full-featured asynchronous I/O library for C, modelled in
similar style and spirit as libev.

Features include: asynchronous read, write, open, close, stat, unlink,
fdatasync, mknod, readdir etc. (basically the full POSIX API), sendfile
(native on Solaris, Linux, HP-UX, FreeBSD, emulated everywhere else),
read-ahead (emulated where not available).  It is fully event-library
agnostic and can easily be integrated into any event-library (or used
standalone, even in polling mode).

WWW: http://software.schmorp.de/pkg/libeio.html