// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Socket control messages

package syscall

import 

// UnixCredentials encodes credentials into a socket control message
// for sending to another process. This can be used for
// authentication.
func ( *Ucred) []byte {
	 := make([]byte, CmsgSpace(SizeofUcred))
	 := (*Cmsghdr)(unsafe.Pointer(&[0]))
	.Level = SOL_SOCKET
	.Type = SCM_CREDENTIALS
	.SetLen(CmsgLen(SizeofUcred))
	*(*Ucred)(.data(0)) = *
	return 
}

// ParseUnixCredentials decodes a socket control message that contains
// credentials in a Ucred structure. To receive such a message, the
// SO_PASSCRED option must be enabled on the socket.
func ( *SocketControlMessage) (*Ucred, error) {
	if .Header.Level != SOL_SOCKET {
		return nil, EINVAL
	}
	if .Header.Type != SCM_CREDENTIALS {
		return nil, EINVAL
	}
	if uintptr(len(.Data)) < unsafe.Sizeof(Ucred{}) {
		return nil, EINVAL
	}
	 := *(*Ucred)(unsafe.Pointer(&.Data[0]))
	return &, nil
}