Allow data pipe producer/consumer handles to be re-sent.

mojo/edk/system/data_pipe_impl.cc

+// Copyright 2015 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 "mojo/edk/system/data_pipe_impl.h"
+
+#include <algorithm>
+
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "mojo/edk/system/configuration.h"
+#include "mojo/edk/system/message_in_transit.h"
+#include "mojo/edk/system/message_in_transit_queue.h"
+
+namespace mojo {
+namespace system {
+
+void DataPipeImpl::ConvertDataToMessages(const char* buffer,
+                                         size_t* start_index,
+                                         size_t* current_num_bytes,
+                                         MessageInTransitQueue* message_queue) {
+  // The maximum amount of data to send per message (make it a multiple of the
+  // element size.
+  size_t max_message_num_bytes = GetConfiguration().max_message_num_bytes;
+  max_message_num_bytes -= max_message_num_bytes % element_num_bytes();
+  DCHECK_GT(max_message_num_bytes, 0u);
+
+  while (*current_num_bytes > 0) {
+    size_t current_contiguous_num_bytes =
+        (*start_index + *current_num_bytes > capacity_num_bytes())
+            ? (capacity_num_bytes() - *start_index)
+            : *current_num_bytes;
+    size_t message_num_bytes =
+        std::min(max_message_num_bytes, current_contiguous_num_bytes);
+
+    // Note: |message_num_bytes| fits in a |uint32_t| since the capacity does.
+    scoped_ptr<MessageInTransit> message(new MessageInTransit(
+        MessageInTransit::kTypeEndpoint, MessageInTransit::kSubtypeEndpointData,
+        static_cast<uint32_t>(message_num_bytes), buffer + *start_index));
+    message_queue->AddMessage(message.Pass());
+
+    DCHECK_LE(message_num_bytes, *current_num_bytes);
+    *start_index += message_num_bytes;
+    *start_index %= capacity_num_bytes();
+    *current_num_bytes -= message_num_bytes;
+  }
+}
+
+}  // namespace system
+}  // namespace mojo