This table lists details relating to the interpretation of the status parameter, based on the opcode.
Symbol |
Interpretation of Status Returned |
TCPOP_ACCEPT |
Status >= 0 indicates success. Any value > 0 implies that you had data in the buffer parameter, which was sent unsolicited to the client - up to 32 bytes. That is an unusual protocol though, and likely to confuse the client. |
TCPOP_WRITE |
Status returns the number of bytes written. <0 indicates an error. Note that for non-blocking connections, a special error value (EWOULDBLOCK, which is -10035 for Windows and typically -11 for Unix) is returned if the socket cannot accept the data immediately. All other errors would suggest a permanent problem requiring the socket to be closed. |
TCPOP_READ |
Status returns the number of bytes read. <0 indicates an error. See note above for TCPOP_WRITE about the special EWOULDBLOCK error. |
TCPOP_SHUTDOWN |
Returns 0 for success, <0 for error. |
TCPOP_CLOSE |
Returns 0 for success, <0 for error. |
TCPOP_CHECK |
Returns 0 to indicate that the socket is not ready—that is, there is no data to read, or, in the case of Asynchronous Client Connections, the socket is not yet connected. <0 indicates an error; probably the socket has been closed at the other end, or the asynchronous connection attempt failed. 1 indicates that the socket has data to read, or the asynchronous connection has successfully completed. |
TCPOP_CHKQTY |
Returns the number of bytes available to read, or <0 for an error. |
TCPOP_CONNECT |
Returns 0 for a successful normal connection, else <0 for error. In the case of Asynchronous Client Connections, 0 indicates that the connection attempt is in progress, while 1 indicates that it connected successfully. |
TCPOP_ERRMSG |
Status should be set to the error code (probably returned from the previous operation) in order to get the error description. This is the one case where status is used for input to the subroutine rather than output from it. |
