[NaCl SDK] nacl_io: Auto-bind UDP socket on first sendto().

native_client_sdk/src/libraries/nacl_io/mount_node_socket.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "nacl_io/ossocket.h"
 #ifdef PROVIDES_SOCKET_API
 
 #include <errno.h>
 #include <string.h>
 
@@ skipping 444 matching lines @@
   }
 
   return ENOTCONN;
 }
 
 Error MountNodeSocket::GetSockName(struct sockaddr* addr, socklen_t* len) {
   if (NULL == addr || NULL == len)
     return EFAULT;
 
   AUTO_LOCK(node_lock_);
-  if (local_addr_ != 0) {
-    *len = ResourceToSockAddr(local_addr_, *len, addr);
+  if (local_addr_ == 0) {
+    // getsockname succeeds even if the socket is not bound. In this case,
+    // just return address 0, port 0.
+    memset(addr, 0, *len);
     return 0;
   }
 
-  return ENOTCONN;
+  *len = ResourceToSockAddr(local_addr_, *len, addr);
+  return 0;
 }
 
 }  // namespace nacl_io
 
 #endif  // PROVIDES_SOCKET_API