libpatterns is a small, embeddable C library which gives your program a pretty decent regular expression engine. You can think of it as PCRE on a diet.
This library is essentially just a redistribution of the code from patterns(7) from OpenBSD's httpd(8), which in turn is based on the pattern-matching code from the Lua language.
The pattern matching is derived from the original implementation of the Lua scripting language written by Roberto Ierusalimschy, Waldemar Celes, and Luiz Henrique de Figueiredo at PUC-Rio. It was turned into a native C API for OpenBSD's httpd(8) by Reyk Floeter. That native C API was repackaged as a system-wide library by Charlotte Koch charlotte@NetBSD.org
This library is released under a 2-clause BSD-style license, but it is mainly a redistribution of code licensed under a MIT-style license and an ISC-style license. See the LICENSE document for details.