code review 126960043: go.sys: copy files from syscall package to go.sys/{plan...

unix/sockcmsg_linux.go

+// 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 "unsafe"
+
+// UnixCredentials encodes credentials into a socket control message
+// for sending to another process. This can be used for
+// authentication.
+func UnixCredentials(ucred *Ucred) []byte {
+        b := make([]byte, CmsgSpace(SizeofUcred))
+        h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
+        h.Level = SOL_SOCKET
+        h.Type = SCM_CREDENTIALS
+        h.SetLen(CmsgLen(SizeofUcred))
+        *((*Ucred)(cmsgData(h))) = *ucred
+        return b
+}
+
+// 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 ParseUnixCredentials(m *SocketControlMessage) (*Ucred, error) {
+        if m.Header.Level != SOL_SOCKET {
+                return nil, EINVAL
+        }
+        if m.Header.Type != SCM_CREDENTIALS {
+                return nil, EINVAL
+        }
+        ucred := *(*Ucred)(unsafe.Pointer(&m.Data[0]))
+        return &ucred, nil
+}