nacl_io: Add SOCK_DGRAM support to socketpair()

native_client_sdk/src/libraries/nacl_io/socket/fifo_packet.cc

Index: native_client_sdk/src/libraries/nacl_io/socket/fifo_packet.cc
diff --git a/native_client_sdk/src/libraries/nacl_io/socket/fifo_packet.cc b/native_client_sdk/src/libraries/nacl_io/socket/fifo_packet.cc
index 3e5c330b52f35babbe5ffd7a5ccf38da6e06b953..cf4a6516764cd43e00aa2651c0c0846b6aaaeb04 100644
--- a/native_client_sdk/src/libraries/nacl_io/socket/fifo_packet.cc
+++ b/native_client_sdk/src/libraries/nacl_io/socket/fifo_packet.cc
@@ -68,4 +68,28 @@ void FIFOPacket::WritePacket(Packet* packet) {
   packets_.push_front(packet);
 }
 
+size_t FIFOPacket::Read(void* buf, size_t len) {
+  Packet* packet = ReadPacket();
+  if (!packet)
+    return 0;
+
+  size_t bytes = packet->len();
+  if (bytes > len)
+    bytes = len;
+  memcpy(buf, packet->buffer(), bytes);
+
+  delete packet;
+  return bytes;
+}
+
+size_t FIFOPacket::Write(const void* buf, size_t len) {
+  if (len > WriteAvailable())
+    return 0;
+
+  Packet* packet = new Packet(NULL);
+  packet->Copy(buf, len, 0);
+  WritePacket(packet);
+  return len;
+}
+
 }  // namespace nacl_io