errno is an external variable whose value is set whenever an error occurs during a call to any of the DEC C RTL routines. You can use this value to obtain a more detailed description of the error. errno is not cleared on successful calls, so its value should be checked only when an error has been indicated.
Most calls to the DEC C RTL routines have one or more returned values. Any error condition is indicated by an otherwise impossible return value. This is almost always -1; the individual routine descriptions specify the details.
All return codes and values from routines are of type int unless otherwise noted. An error number is also made available in the external variable errno, which is not cleared on successful calls. The errno values may be translated to a message, similar to that found in UNIX systems, by using the perror routine. vaxc$errno may also be returned as an error.
Table A-2 lists the errno values.
| Value | Meaning |
|---|---|
| EINPROGRESS | Operation now in progress |
| An operation that takes a long time to complete, such as connect, was attempted on a nonblocking object. | |
| EALREADY | Operation already in progress |
| An operation was attempted on a nonblocking object that already had an operation in progress. | |
| ENOTSOCK | Socket operation on a non-socket |
| EDESTADDRREQ | Destination address required |
| A required address was omitted from an operation on a socket. | |
| EMSGSIZE | Message too long |
| A message sent on a socket was larger than the internal message buffer. | |
| EPROTOTYPE | Protocol wrong type for socket |
| A protocol was specified that does not support the semantics of the socket type requested. For example, you cannot use the ARPA Internet UDP protocol with type SOCK_STREAM. | |
| ENOPROTOOPT | Protocol not available |
| A bad option was specified in a getsockopt or setsocketopt call. | |
| EPROTONOSUPPORT | Protocol not supported |
| The protocol has not been configured into the system or no implementation for it exists. | |
| ESOCKTNOSUPPORT | Socket type not supported |
| The support for the socket type has not been configured into the system or no implementation for it exists. | |
| EOPNOTSUPP | Error-operation not supported |
| For example, trying to accept a connection on a datagram socket. | |
| EPFNOSUPPORT | Protocol family not supported |
| The protocol family has not been configured into the system or no implementation for it exists. | |
| EAFNOSUPPORT | Address family not supported by protocol family |
| An address incompatible with the requested protocol was used. | |
| EADDRINUSE | Address already in use |
| Each address can be used only once. | |
| EADDRNOTAVAIL | Cannot assign requested address |
| Normally, results from an attempt to create a socket with an address not on this machine. | |
| ENETDOWN | Network is down |
| A socket operation encountered a dead network. | |
| ENETUNREACH | Network is unreachable |
| A socket operation was attempted to an unreachable network. | |
| ENETRESET | Network dropped connection on reset |
| The host you were connected to crashed and rebooted. | |
| ECONNABORTED | Software caused connection abort |
| A connection abort was caused internal to your host machine. | |
| ECONNRESET | Connection reset by peer |
| A connection was forcibly closed by a peer. This usually results from the peer executing a shutdown call. | |
| ENOBUFS | No buffer space available |
| An operation on a socket or pipe was not performed because the system lacked sufficient buffer space. | |
| EISCONN | Socket is already connected |
| A connect request was made on an already connected socket; or, a sendto or sendmsg request on a connected socket specified a destination other than the connected party. | |
| ENTOTCONN | Socket is not connected |
| Request to send or receive data was disallowed because the socket is not connected. | |
| ESHUTDOWN | Cannot send after socket shutdown |
| A request to send data was disallowed because the socket had already been shut down with a previous shutdown call. | |
| ETOOMANYREFS | Too many references: cannot splice |
| ETIMEDOUT | Connection timed out |
| A connect request failed because the connected party did not properly respond after a period of time. (The timeout period is dependent on the communication protocol.) A connect request or remote file operation failed because the connected party did not properly respond after a period of time that is dependent on the communication protocol. | |
| ECONNREFUSED | Connection refused |
| No connection could be made because the target machine actively refused it. This usually results from trying to connect to a service that is inactive on the foreign host. | |
| ELOOP | Too many levels of symbolic links |
| A path name lookup involved more than eight symbolic links. | |
| ENAMETOOLONG | File name too long |
| A component of a path name exceeded 255 characters, or an entire path name exceeded 1023 characters. | |
| EHOSTDOWN | Host is down |
| A socket operation failed because the destination host was down. | |
| EHOSTUNREACH | No route to host |
| A socket operation was attempted to an unreachable host. | |
| EVMSERR | OpenVMS system-specific error code that is nontranslatable |