bind, listen, accept, connect, shutdown, getsockname, getsockopt, setsockopt, send, recv and the other calls that look up a guest socket answered EBADF for a descriptor that is open but not a socket, for example a pipe end. FreeBSD 11.4's getsock_cap fails these with ENOTSOCK and keeps EBADF for a closed or invalid descriptor.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>