Add LOCAL_PEEREID sockopt support for peer socket uid check

It is supported on NetBSD 5 and later.

Signed-off-by: OBATA Akio <obache@wizdas.com>
(cherry picked from commit 7827038ab4)

dcop/dcopclient.cpp

@@ -41,6 +41,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 #include <sys/stat.h>
 #include <sys/file.h>
 #include <sys/socket.h>
+#include <sys/un.h>
 #include <fcntl.h>
 #include <unistd.h>
 
@@ -713,10 +714,12 @@ bool DCOPClient::isSuspended() const
     return !d->notifier->isEnabled();
 }
 
-#ifdef SO_PEERCRED
+#if defined(SO_PEERCRED) || defined(LOCAL_PEEREID)
+#define USE_PEER_IS_US
 // Check whether the remote end is owned by the same user.
 static bool peerIsUs(int sockfd)
 {
+#ifdef SO_PEERCRED
 #if defined(__OpenBSD__)
     struct sockpeercred cred;
 #else
@@ -726,6 +729,13 @@ static bool peerIsUs(int sockfd)
     if (getsockopt(sockfd, SOL_SOCKET, SO_PEERCRED, &cred, &siz) != 0)
         return false;
     return (cred.uid == getuid());
+#elif defined LOCAL_PEEREID
+    struct unpcbid cred;
+    socklen_t siz = sizeof(cred);
+    if (getsockopt(sockfd, 0, LOCAL_PEEREID, &cred, &siz) != 0 || siz != sizeof(cred))
+        return false;
+    return (cred.unp_euid == geteuid());
+#endif
 }
 #else
 // Check whether the socket is owned by the same user.
@@ -871,7 +881,7 @@ bool DCOPClient::attachInternal( bool registerAsAnonymous )
         return false;
     }
 
-#ifdef SO_PEERCRED
+#ifdef USE_PEER_IS_US
     d->foreign_server = !peerIsUs(socket());
 #else
     d->foreign_server = !isServerSocketOwnedByUser(d->serverAddr);