Query: getsockopt
OS: ultrix
Section: 2
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getsockopt(2) System Calls Manual getsockopt(2) Name getsockopt, setsockopt - get or set options on sockets Syntax #include <sys/types.h> #include <sys/socket.h> getsockopt(s, level, optname, optval, optlen) int s, level, optname; char *optval; int *optlen; setsockopt(s, level, optname, optval, optlen) int s, level, optname; char *optval; int optlen; Description The and system calls manipulate options associated with a socket. Options can exist at multiple protocol levels; they are always present at the uppermost socket level. When manipulating socket options, the level at which the option resides and the name of the option must be specified. To manipulate options at the socket level, level is specified as SOL_SOCKET. To manipulate options at any other level, the protocol number of the appro- priate protocol controlling the option must be supplied. For example, to indicate an option is to be interpreted by the TCP protocol, level should be set to the protocol number of TCP. For further information, see The parameters optval and optlen are used to access option values for For they identify a buffer in which the values for the requested options are to be returned. For optlen is a value-result parameter, initially containing the size of the buffer pointed to by optval and modified on return to indicate the actual size of the value returned. If no option value is to be supplied or returned, optval can be sup- plied as 0. The optname parameter and any specified options are passed uninterpreted to the appropriate protocol module for interpretation. The include file <sys/socket.h> contains definitions for socket level options. For further information, see Options at other protocol levels vary in format and name. Consult the or reference pages for details. Return Values A zero is returned if the call succeeds, and -1 is returned if it fails. Diagnostics The call fails under the following conditions: [EBADF] The argument s is not a valid descriptor. [ENOTSOCK] The argument s is a file, not a socket. [ENOPROTOOPT] The option is unknown. [EFAULT] The address pointed to by optval is not in a valid part of the process address space. For this error can also be returned if optlen is not in a valid part of the process address space. See Also fcntl(2), socket(2), getprotoent(3n), Guide to the Data Link Interface getsockopt(2)