Adds a generator for writing messages to disk

mojo/tools/message_generator.cc

Index: mojo/tools/message_generator.cc
diff --git a/mojo/tools/message_generator.cc b/mojo/tools/message_generator.cc
new file mode 100644
index 0000000000000000000000000000000000000000..86fcab21af150a21fd8e30a5b47fa72ad536cb2e
--- /dev/null
+++ b/mojo/tools/message_generator.cc
@@ -0,0 +1,63 @@
+// Copyright 2014 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 "base/file_util.h"
+#include "base/files/file_path.h"
+#include "base/strings/string_util.h"
+#include "base/strings/stringprintf.h"
+#include "mojo/public/cpp/bindings/lib/message_builder.h"
+#include "mojo/public/cpp/bindings/lib/message_internal.h"
+#include "mojo/public/cpp/bindings/message.h"
+
+// This file is used to generate various files corresponding to mojo
+// messages. The various binding implementations can parse these to verify they
+// correctly decode messages.
+//
+// The output consists of each byte of the message encoded in a hex string with
+// a newline after it.
+namespace mojo {
+namespace {
+
+std::string BinaryToHex(const base::StringPiece& piece) {
+  std::string result("// File generated by mojo_message_generator.\n");;
+  result.reserve(result.size() + (piece.size() * 5));
+  for (size_t i = 0; i < piece.size(); ++i)
+    base::StringAppendF(&result, "0X%.2X\n", static_cast<int>(piece.data()[i]));
+  return result;
+}
+
+void WriteMessageToFile(const Message& message, const base::FilePath& path) {
+  const std::string hex_message(BinaryToHex(
+      base::StringPiece(reinterpret_cast<const char*>(message.data()),
+                        message.data_num_bytes())));
+  CHECK_EQ(static_cast<int>(hex_message.size()),
+           base::WriteFile(path, hex_message.data(),
+                           static_cast<int>(hex_message.size())));
+}
+
+// Generates a message of type MessageData. The message uses the name 21,
+// with 4 bytes of payload: 0x9, 0x8, 0x7, 0x6.
+void GenerateMessageDataMessage() {
+  internal::MessageBuilder builder(static_cast<uint32_t>(21),
+                                   static_cast<size_t>(4));
+  char* data = static_cast<char*>(builder.buffer()->Allocate(4));
+  DCHECK(data);
+  data[0] = 9;
+  data[1] = 8;
+  data[2] = 7;
+  data[3] = 6;
+
+  Message message;
+  builder.Finish(&message);
+  WriteMessageToFile(message,
+                     base::FilePath(FILE_PATH_LITERAL("message_data")));
+}
+
+}  // namespace
+}  // namespace mojo
+
+int main(int argc, char** argv) {
+  mojo::GenerateMessageDataMessage();
+  return 0;
+}