Add a Mojo EDK for Chrome that uses one OS pipe per message pipe.

mojo/edk/system/data_pipe.cc

Index: mojo/edk/system/data_pipe.cc
diff --git a/mojo/edk/system/data_pipe.cc b/mojo/edk/system/data_pipe.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ce04bf9a027a9b0b009445b0487d0f80a5f58e76
--- /dev/null
+++ b/mojo/edk/system/data_pipe.cc
@@ -0,0 +1,203 @@
+// 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.h"
+
+#include <string.h>
+
+#include "mojo/edk/system/configuration.h"
+#include "mojo/edk/system/options_validation.h"
+#include "mojo/edk/system/raw_channel.h"
+#include "mojo/edk/system/transport_data.h"
+
+namespace mojo {
+namespace edk {
+
+namespace {
+
+const size_t kInvalidDataPipeHandleIndex = static_cast<size_t>(-1);
+
+struct MOJO_ALIGNAS(8) SerializedDataPipeHandleDispatcher {
+  size_t platform_handle_index;  // (Or |kInvalidDataPipeHandleIndex|.)
+
+  // These are from MojoCreateDataPipeOptions
+  MojoCreateDataPipeOptionsFlags flags;
+  uint32_t element_num_bytes;
+  uint32_t capacity_num_bytes;
+
+  size_t shared_memory_handle_index;  // (Or |kInvalidDataPipeHandleIndex|.)
+  uint32_t shared_memory_size;
+};
+
+}  // namespace
+
+MojoCreateDataPipeOptions DataPipe::GetDefaultCreateOptions() {
+  MojoCreateDataPipeOptions result = {
+      static_cast<uint32_t>(sizeof(MojoCreateDataPipeOptions)),
+      MOJO_CREATE_DATA_PIPE_OPTIONS_FLAG_NONE,
+      1u,
+      static_cast<uint32_t>(
+          GetConfiguration().default_data_pipe_capacity_bytes)};
+  return result;
+}
+
+MojoResult DataPipe::ValidateCreateOptions(
+    const MojoCreateDataPipeOptions* in_options,
+    MojoCreateDataPipeOptions* out_options) {
+  const MojoCreateDataPipeOptionsFlags kKnownFlags =
+      MOJO_CREATE_DATA_PIPE_OPTIONS_FLAG_NONE;
+
+  *out_options = GetDefaultCreateOptions();
+  if (!in_options)
+    return MOJO_RESULT_OK;
+
+  UserOptionsReader<MojoCreateDataPipeOptions> reader(in_options);
+  if (!reader.is_valid())
+    return MOJO_RESULT_INVALID_ARGUMENT;
+
+  if (!OPTIONS_STRUCT_HAS_MEMBER(MojoCreateDataPipeOptions, flags, reader))
+    return MOJO_RESULT_OK;
+  if ((reader.options().flags & ~kKnownFlags))
+    return MOJO_RESULT_UNIMPLEMENTED;
+  out_options->flags = reader.options().flags;
+
+  // Checks for fields beyond |flags|:
+
+  if (!OPTIONS_STRUCT_HAS_MEMBER(MojoCreateDataPipeOptions, element_num_bytes,
+                                 reader))
+    return MOJO_RESULT_OK;
+  if (reader.options().element_num_bytes == 0)
+    return MOJO_RESULT_INVALID_ARGUMENT;
+  out_options->element_num_bytes = reader.options().element_num_bytes;
+
+  if (!OPTIONS_STRUCT_HAS_MEMBER(MojoCreateDataPipeOptions, capacity_num_bytes,
+                                 reader) ||
+      reader.options().capacity_num_bytes == 0) {
+    // Round the default capacity down to a multiple of the element size (but at
+    // least one element).
+    size_t default_data_pipe_capacity_bytes =
+        GetConfiguration().default_data_pipe_capacity_bytes;
+    out_options->capacity_num_bytes =
+        std::max(static_cast<uint32_t>(default_data_pipe_capacity_bytes -
+                                       (default_data_pipe_capacity_bytes %
+                                        out_options->element_num_bytes)),
+                 out_options->element_num_bytes);
+    return MOJO_RESULT_OK;
+  }
+  if (reader.options().capacity_num_bytes % out_options->element_num_bytes != 0)
+    return MOJO_RESULT_INVALID_ARGUMENT;
+  if (reader.options().capacity_num_bytes >
+      GetConfiguration().max_data_pipe_capacity_bytes)
+    return MOJO_RESULT_RESOURCE_EXHAUSTED;
+  out_options->capacity_num_bytes = reader.options().capacity_num_bytes;
+
+  return MOJO_RESULT_OK;
+}
+
+void DataPipe::StartSerialize(bool have_channel_handle,
+                              bool have_shared_memory,
+                              size_t* max_size,
+                              size_t* max_platform_handles) {
+  *max_size = sizeof(SerializedDataPipeHandleDispatcher);
+  *max_platform_handles = 0;
+  if (have_channel_handle)
+    (*max_platform_handles)++;
+  if (have_shared_memory)
+    (*max_platform_handles)++;
+  DCHECK_LE(*max_size, TransportData::kMaxSerializedDispatcherSize);
+}
+
+void DataPipe::EndSerialize(const MojoCreateDataPipeOptions& options,
+                            ScopedPlatformHandle channel_handle,
+                            ScopedPlatformHandle shared_memory_handle,
+                            size_t shared_memory_size,
+                            void* destination,
+                            size_t* actual_size,
+                            PlatformHandleVector* platform_handles) {
+  SerializedDataPipeHandleDispatcher* serialization =
+      static_cast<SerializedDataPipeHandleDispatcher*>(destination);
+  if (channel_handle.is_valid()) {
+    serialization->platform_handle_index = platform_handles->size();
+    platform_handles->push_back(channel_handle.release());
+  } else {
+    serialization->platform_handle_index = kInvalidDataPipeHandleIndex;
+  }
+
+  serialization->flags = options.flags;
+  serialization->element_num_bytes = options.element_num_bytes;
+  serialization->capacity_num_bytes = options.capacity_num_bytes;
+
+  serialization->shared_memory_size = static_cast<uint32_t>(shared_memory_size);
+  if (serialization->shared_memory_size) {
+    serialization->shared_memory_handle_index = platform_handles->size();
+    platform_handles->push_back(shared_memory_handle.release());
+  }
+
+  *actual_size = sizeof(SerializedDataPipeHandleDispatcher);
+}
+
+ScopedPlatformHandle DataPipe::Deserialize(
+    const void* source,
+    size_t size,
+    PlatformHandleVector* platform_handles,
+    MojoCreateDataPipeOptions* options,
+    ScopedPlatformHandle* shared_memory_handle,
+    size_t* shared_memory_size) {
+  if (size != sizeof(SerializedDataPipeHandleDispatcher)) {
+    LOG(ERROR) << "Invalid serialized platform handle dispatcher (bad size)";
+    return ScopedPlatformHandle();
+  }
+
+  const SerializedDataPipeHandleDispatcher* serialization =
+      static_cast<const SerializedDataPipeHandleDispatcher*>(source);
+  size_t platform_handle_index = serialization->platform_handle_index;
+
+  // Starts off invalid, which is what we want.
+  PlatformHandle platform_handle;
+  if (platform_handle_index != kInvalidDataPipeHandleIndex) {
+    if (!platform_handles ||
+        platform_handle_index >= platform_handles->size()) {
+      LOG(ERROR)
+          << "Invalid serialized platform handle dispatcher (missing handles)";
+      return ScopedPlatformHandle();
+    }
+
+    // We take ownership of the handle, so we have to invalidate the one in
+    // |platform_handles|.
+    std::swap(platform_handle, (*platform_handles)[platform_handle_index]);
+  }
+
+  options->struct_size = sizeof(MojoCreateDataPipeOptions);
+  options->flags = serialization->flags;
+  options->element_num_bytes = serialization->element_num_bytes;
+  options->capacity_num_bytes = serialization->capacity_num_bytes;
+
+  if (shared_memory_size) {
+    *shared_memory_size = serialization->shared_memory_size;
+    if (*shared_memory_size) {
+      DCHECK(serialization->shared_memory_handle_index !=
+             kInvalidDataPipeHandleIndex);
+      if (!serialization->shared_memory_handle_index ||
+          serialization->shared_memory_handle_index >=
+              platform_handles->size()) {
+        LOG(ERROR) << "Invalid serialized platform handle dispatcher "
+                   << "(missing handles)";
+        return ScopedPlatformHandle();
+      }
+
+      PlatformHandle temp_shared_memory_handle;
+      std::swap(temp_shared_memory_handle,
+                (*platform_handles)[serialization->shared_memory_handle_index]);
+      *shared_memory_handle =
+          ScopedPlatformHandle(temp_shared_memory_handle);
+    }
+  }
+
+  size -= sizeof(SerializedDataPipeHandleDispatcher);
+
+  return ScopedPlatformHandle(platform_handle);
+}
+
+}  // namespace edk
+}  // namespace mojo