1 files changed, 105 insertions, 0 deletions
diff --git a/ipc/chromium/src/chrome/common/ipc_message_utils.cc b/ipc/chromium/src/chrome/common/ipc_message_utils.cc
new file mode 100644
index 0000000000..49cb277e5f
--- /dev/null
+++ b/ipc/chromium/src/chrome/common/ipc_message_utils.cc
@@ -0,0 +1,105 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "chrome/common/ipc_message_utils.h"
+#include "mozilla/ipc/SharedMemory.h"
+#include "mozilla/ipc/SharedMemoryBasic.h"
+
+namespace IPC {
+
+static uint32_t kShmemThreshold = 64 * 1024;
+
+MessageBufferWriter::MessageBufferWriter(MessageWriter* writer,
+                                         uint32_t full_len)
+    : writer_(writer) {
+  if (full_len > kShmemThreshold) {
+    shmem_ = new mozilla::ipc::SharedMemoryBasic();
+    if (!shmem_->Create(full_len)) {
+      writer->FatalError("SharedMemory::Create failed!");
+      return;
+    }
+    if (!shmem_->Map(full_len)) {
+      writer->FatalError("SharedMemory::Map failed");
+      return;
+    }
+    if (!shmem_->WriteHandle(writer)) {
+      writer->FatalError("SharedMemory::WriterHandle failed");
+      return;
+    }
+    buffer_ = reinterpret_cast<char*>(shmem_->memory());
+  }
+  remaining_ = full_len;
+}
+
+MessageBufferWriter::~MessageBufferWriter() {
+  if (remaining_ != 0) {
+    writer_->FatalError("didn't fully write message buffer");
+  }
+}
+
+bool MessageBufferWriter::WriteBytes(const void* data, uint32_t len) {
+  MOZ_RELEASE_ASSERT(len == remaining_ || (len % 4) == 0,
+                     "all writes except for the final write must be a multiple "
+                     "of 4 bytes in length due to padding");
+  if (len > remaining_) {
+    writer_->FatalError("MessageBufferWriter overrun");
+    return false;
+  }
+  remaining_ -= len;
+  // If we're serializing using a shared memory region, `buffer_` will be
+  // initialized to point into that region.
+  if (buffer_) {
+    memcpy(buffer_, data, len);
+    buffer_ += len;
+    return true;
+  }
+  return writer_->WriteBytes(data, len);
+}
+
+MessageBufferReader::MessageBufferReader(MessageReader* reader,
+                                         uint32_t full_len)
+    : reader_(reader) {
+  if (full_len > kShmemThreshold) {
+    shmem_ = new mozilla::ipc::SharedMemoryBasic();
+    if (!shmem_->ReadHandle(reader)) {
+      reader->FatalError("SharedMemory::ReadHandle failed!");
+      return;
+    }
+    if (!shmem_->Map(full_len)) {
+      reader->FatalError("SharedMemory::Map failed");
+      return;
+    }
+    buffer_ = reinterpret_cast<const char*>(shmem_->memory());
+  }
+  remaining_ = full_len;
+}
+
+MessageBufferReader::~MessageBufferReader() {
+  if (remaining_ != 0) {
+    reader_->FatalError("didn't fully write message buffer");
+  }
+}
+
+bool MessageBufferReader::ReadBytesInto(void* data, uint32_t len) {
+  MOZ_RELEASE_ASSERT(len == remaining_ || (len % 4) == 0,
+                     "all reads except for the final read must be a multiple "
+                     "of 4 bytes in length due to padding");
+  if (len > remaining_) {
+    reader_->FatalError("MessageBufferReader overrun");
+    return false;
+  }
+  remaining_ -= len;
+  // If we're serializing using a shared memory region, `buffer_` will be
+  // initialized to point into that region.
+  if (buffer_) {
+    memcpy(data, buffer_, len);
+    buffer_ += len;
+    return true;
+  }
+  return reader_->ReadBytesInto(data, len);
+}
+
+}  // namespace IPC