Interprocess communication using UNIX domain sockets

List of error codes

In the following is a list of networking error codes, the protocol or operation during which the error is likely to occur is given at the beginning of the explanation.

NOTE: If a connection fails at any time, the socket cannot be re-used; it must be closed and a new socket created.

I/O errors

EALREADY Operation already in progress  
EINPROGRESS Operation now in progress  
EWOULDBLOCK Operation would block  

Argument errors

EADDRINUSE Address already in use An attempt was made to create a socket with a UNIX pathname which already exists.
EAFNOSUPPORT Address family not supported by protocol family  
EDESTADDRREQ Destination address required  
EMSGSIZE Message too long  
ENOTSOCK Socket operation on non-socket  
EOPNOTSUPP Operation not supported on socket  
EPFNOSUPPORT Protocol family not supported  
EPROTONOSUPPORT Protocol not supported Creating a socket. Unknown protocol or protocol not supported.
EPROTOTYPE Protocol wrong type for socket Creating a socket. Socket type request has no supporting protocol.
ESOCKTNOSUPPORT Socket type not supported  

Operational errors

ECONNABORTED Software caused connection abort  
ECONNREFUSED Connection refused Socket connection. The host refused service for some reason. This error is usually caused by a server process not being present at the requested name.
ECONNRESET Connection reset by peer The remote peer forced the session to be closed.
EISCONN Socket is already connected An attempt was made to establish a connection on a socket that already has one or an attempt was made to send a datagram with the destination address specified and the socket is already connected.
ENOBUFS No buffer space available Any socket operation. The system lacks sufficient memory for an internal data structure.
ENOENT No such file or directory Connection could not be established.
ENOTCONN Socket is not connected An attempt was made to send a datagram, but no destination address is specified, and the socket has not been connected.
ESHUTDOWN Cannot send after socket shutdown  

Miscellaneous errors

ENOPROTOOPT Protocol not available  

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SCO OpenServer Release 5.0.7 -- 11 February 2003