peek methods for UnixDatagram and UnixStream?

[joshtriplett]

#38980 added peek and peek_from methods for UdpSocket, and added peek to TcpStream.

Would it be possible to add the peek and peek_from methods to UnixDatagram as well, and to add the peek method to UnixStream?

I would also be interested in having a Linux extension method for UnixDatagram that calls recv with MSG_PEEK | MSG_TRUNC, to block until the next packet is available and return the length of that packet. Perhaps next_packet_len()? (Doing that is possible on some other platforms via different methods, but some platforms can't do it at all without just reading and buffering the pending packet via MSG_PEEK with increasingly large buffers.)

[rijenkii]

Just FYI - socket2::Socket has a peek method, and can be constructed with the help of From<UnixStream>, From<UnixDatagram> and From<UnixListener>