getsockopt(2) — DG/UX R4.11MU05



getsockopt(2)                  DG/UX R4.11MU05                 getsockopt(2)


NAME
       getsockopt - get options on a socket

SYNOPSIS
       #include <sys/socket.h>

       int  getsockopt (s, level, optname, optval, optlen)
       int  s;
       int  level;
       int  optname;
       void * optval;
       int  * optlen;

   where:
       s         File descriptor of socket to get options from
       level     Level in socket that the options apply to
       optname   Name of option to return (options are defined in socket.h)
       optval    Buffer to receive options
       optlen    On input contains the number of bytes available for the
                 options; updated to indicate the number of bytes returned

DESCRIPTION
       Getsockopt retrieves options associated with a socket.  Options may
       exist at multiple protocol levels; they are always present at the
       uppermost socket level.

       When getting socket options, the caller must specify the level at
       which the option resides and the name of the option.  To retrieve
       options at the socket level, level is specified as SOL_SOCKET.  To
       get options at any other level, the protocol number of the
       appropriate protocol controlling the option is supplied.  Consult
       domain specific documentation for more information related to a
       specific protocol.

       The parameters optval and optlen identify a buffer in which the value
       for the requested option(s) are to be returned.  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 returned,
       optval may be supplied as 0.  If the buffer isn't large enough for
       the options, they will be truncated.

       Optname 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; see
       socket.  Options at other protocol levels vary in format and name;
       consult the related documentation for the domain of the socket.

ACCESS CONTROL
       SOL_SOCKET has no access restrictions.  (See domain-specific
       documentation for any domain restrictions.)

RETURN VALUE
       0      Completed successfully.

       -1     An error occurred.  errno is set to indicate the error.

DIAGNOSTICS
       Errno may be set to one of the following error codes:

       EBADF          The argument s is not an active valid descriptor.

       ENOTSOCK       The argument s is not a file of type S_IFSOCK (socket
                      special).

       ENOPROTOOPT    The option is unknown.

       EFAULT         The optval is not in a valid part of the process
                      address space, or optlen < 0.

       ENOBUFS        No internal buffers available.

SEE ALSO
       setsockopt(2), socket(2), inet(3N), inet(6F), tcp(6P), udp(6P),
       unixipc(6F).


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