优秀C语言开源代码

lighttpd， webserver， http://www.lighttpd.net/

nginx ，webserver，http://nginx.org/

varnish，a web application accelerator，https://www.varnish-cache.org/

glibc, libs for c, http://www.gnu.org/software/libc/libc.html

gtk, gui toolkit，http://www.gtk.org/

busybox, unix-like utilities, http://www.busybox.net/

netfilter&iptables，http://www.netfilter.org/

redis,key-value store system, http://redis.io/

memcached,memory object caching system, http://memcached.org/

Python, both the interpreter (in C) and libraries (in Python.)

LCC, the lightweight C compiler along with the excellent book documenting it: A Retargetable C Compiler: Design and Implementation by David R. Hanson. It's worth reading even if you have no interest in writing compilers.