recvfrom_nonblock

/*
 * call-seq:
 *      socket.recvfrom_nonblock(maxlen) => [mesg, sender_sockaddr]
 *      socket.recvfrom_nonblock(maxlen, flags) => [mesg, sender_sockaddr]
 * 
 * Receives up to _maxlen_ bytes from +socket+ using recvfrom(2) after
 * O_NONBLOCK is set for the underlying file descriptor.
 * _flags_ is zero or more of the +MSG_+ options.
 * The first element of the results, _mesg_, is the data received.
 * The second element, _sender_sockaddr_, contains protocol-specific information
 * on the sender.
 *
 * When recvfrom(2) returns 0, Socket#recvfrom_nonblock returns
 * an empty string as data.
 * The meaning depends on the socket: EOF on TCP, empty packet on UDP, etc.
 * 
 * === Parameters
 * * +maxlen+ - the number of bytes to receive from the socket
 * * +flags+ - zero or more of the +MSG_+ options 
 * 
 * === Example
 *      # In one file, start this first
 *      require 'socket'
 *      include Socket::Constants
 *      socket = Socket.new(AF_INET, SOCK_STREAM, 0)
 *      sockaddr = Socket.sockaddr_in(2200, 'localhost')
 *      socket.bind(sockaddr)
 *      socket.listen(5)
 *      client, client_sockaddr = socket.accept
 *      begin
 *        pair = client.recvfrom_nonblock(20)
 *      rescue Errno::EAGAIN, Errno::EWOULDBLOCK
 *        IO.select([client])
 *        retry
 *      end
 *      data = pair[0].chomp
 *      puts "I only received 20 bytes '#{data}'"
 *      sleep 1
 *      socket.close
 * 
 *      # In another file, start this second
 *      require 'socket'
 *      include Socket::Constants
 *      socket = Socket.new(AF_INET, SOCK_STREAM, 0)
 *      sockaddr = Socket.sockaddr_in(2200, 'localhost')
 *      socket.connect(sockaddr)
 *      socket.puts "Watch this get cut short!"
 *      socket.close 
 * 
 * Refer to Socket#recvfrom for the exceptions that may be thrown if the call
 * to _recvfrom_nonblock_ fails. 
 *
 * Socket#recvfrom_nonblock may raise any error corresponding to recvfrom(2) failure,
 * including Errno::EAGAIN.
 *
 * === See
 * * Socket#recvfrom
 */
static VALUE
sock_recvfrom_nonblock(int argc, VALUE *argv, VALUE sock)
{
    return s_recvfrom_nonblock(sock, argc, argv, RECV_SOCKET);
}