https://github.com/bminor/glibc/blob/21c3f4b5368686ade28d90d8c7d79c4c95c72c1b/socket/sys/socket.h#L215 I see setsockopt() is declared above. But I don't find its source code. Where is it defined? Thanks. https://github.com/bminor/glibc/blob/21c3f4b5368686ade28d90d8c7d79c4c95c72c1b/socket/setsockopt.c -- Regards, Peng