iostream.py 文件源码

def read_from_fd(self):
        if self._ssl_accepting:
            # If the handshake hasn't finished yet, there can't be anything
            # to read (attempting to read may or may not raise an exception
            # depending on the SSL version)
            return None
        try:
            # SSLSocket objects have both a read() and recv() method,
            # while regular sockets only have recv().
            # The recv() method blocks (at least in python 2.6) if it is
            # called when there is nothing to read, so we have to use
            # read() instead.
            chunk = self.socket.read(self.read_chunk_size)
        except ssl.SSLError as e:
            # SSLError is a subclass of socket.error, so this except
            # block must come first.
            if e.args[0] == ssl.SSL_ERROR_WANT_READ:
                return None
            else:
                raise
        except socket.error as e:
            if e.args[0] in _ERRNO_WOULDBLOCK:
                return None
            else:
                raise
        if not chunk:
            self.close()
            return None
        return chunk