Attempt to read data from an active channel stream. All channel streams have
one standard I/O substream (stream_id == 0), and may have up to 2^32 extended
data streams as identified by the selected stream_id. The SSH2 protocol
currently defines a stream ID of 1 to be the stderr substream.
channel - active channel stream to read from.
stream_id - substream ID number (e.g. 0 or SSH_EXTENDED_DATA_STDERR)
Actual number of bytes read or negative on failure. It returns
LIBSSH2_ERROR_EAGAIN when it would otherwise block. While
LIBSSH2_ERROR_EAGAIN is a negative number, it isn't really a failure per se.
Note that a return value of zero (0) can in fact be a legitimate value and
only signals that no payload data was read. It is not an error.
ERRORS
LIBSSH2_ERROR_SOCKET_SEND - Unable to send data on socket.
LIBSSH2_ERROR_CHANNEL_CLOSED - The channel has been closed.