Create a broker interface for the new Mojo EDK so that the browser can create and duplicate messa...

mojo/edk/system/parent_token_serializer_win.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/parent_token_serializer_win.h"
+
+#include "base/bind.h"
+#include "base/lazy_instance.h"
+#include "mojo/edk/embedder/platform_channel_pair.h"
+#include "mojo/edk/system/configuration.h"
+#include "mojo/edk/system/parent_token_serializer_state_win.h"
+#include "mojo/edk/system/token_serializer_messages_win.h"
+
+namespace mojo {
+namespace edk {
+
+namespace {
+static const int kDefaultReadBufferSize = 256;
+}
+
+ParentTokenSerializer::ParentTokenSerializer(HANDLE child_process,
+                                             ScopedPlatformHandle pipe)
+    : child_process_(child_process),
+      pipe_(pipe.Pass()),
+      num_bytes_read_(0) {
+  memset(&read_context_.overlapped, 0, sizeof(read_context_.overlapped));
+  read_context_.handler = this;
+  memset(&write_context_.overlapped, 0, sizeof(write_context_.overlapped));
+  write_context_.handler = this;
+
+  ParentTokenSerializerState::GetInstance()->token_serialize_thread()->PostTask(
+      FROM_HERE,
+      base::Bind(&ParentTokenSerializer::RegisterIOHandler,
+                 base::Unretained(this)));
+  read_data_.resize(kDefaultReadBufferSize);

[yzshen1, 2015/11/20 20:39:55]

Please move this resize() above the post task. Because it is possible (though
unlikely) the task will be run before line 35 is run, which results in a race.

[jam, 2015/11/21 01:26:09]

done, good catch

+}
+
+ParentTokenSerializer::~ParentTokenSerializer() {
+}
+
+void ParentTokenSerializer::RegisterIOHandler() {
+  base::MessageLoopForIO::current()->RegisterIOHandler(
+      pipe_.get().handle, this);
+  BeginRead();
+}
+
+void ParentTokenSerializer::BeginRead() {
+  BOOL rv = ReadFile(pipe_.get().handle, &read_data_[num_bytes_read_],
+                     static_cast<int>(read_data_.size() - num_bytes_read_),
+                     nullptr, &read_context_.overlapped);
+  DCHECK(rv ||
+         GetLastError() == ERROR_IO_PENDING ||
+         GetLastError() == ERROR_BROKEN_PIPE);

[yzshen1, 2015/11/20 20:39:55]

When the result is ERROR_BROKEN_PIPE, do we still get a call of OnIOCompleted so
that we can delete this?

[jam, 2015/11/21 01:26:09]

good point, deleted for broken pipe case

+}
+
+void ParentTokenSerializer::OnIOCompleted(
+    base::MessageLoopForIO::IOContext* context,
+    DWORD bytes_transferred,
+    DWORD error) {
+  if (context != &read_context_)
+    return;
+
+  if (error == ERROR_BROKEN_PIPE) {
+    delete this;
+    return;  // Child process exited or crashed.
+  }
+
+  if (error != ERROR_SUCCESS) {
+    NOTREACHED() << "Error " << error << " in ParentTokenSerializer.";
+    delete this;
+    return;
+  }
+
+  num_bytes_read_ += bytes_transferred;
+  CHECK_GE(num_bytes_read_, sizeof(uint32_t));
+  TokenSerializerMessage* message =
+      reinterpret_cast<TokenSerializerMessage*>(&read_data_[0]);
+  if (num_bytes_read_ < message->size) {
+    read_data_.resize(message->size);
+    BeginRead();
+    return;
+  }
+
+  if (message->id == CREATE_PLATFORM_CHANNEL_PAIR) {
+    PlatformChannelPair channel_pair;
+    uint32_t response_size = 2 * sizeof(HANDLE);
+    write_data_.resize(response_size);
+    HANDLE* handles = reinterpret_cast<HANDLE*>(&write_data_[0]);
+    handles[0] = DuplicateToChild(
+        channel_pair.PassServerHandle().release().handle);
+    handles[1] = DuplicateToChild(
+        channel_pair.PassClientHandle().release().handle);
+  } else if (message->id == HANDLE_TO_TOKEN) {
+    uint32_t count =
+        (message->size - kTokenSerializerMessageHeaderSize) / sizeof(HANDLE);
+    if (count > GetConfiguration().max_message_num_handles) {
+      NOTREACHED() << "Too many handles from child process. Closing channel.";
+      delete this;
+      return;
+    }
+    uint32_t response_size = count * sizeof(uint64_t);
+    write_data_.resize(response_size);
+    uint64_t* tokens = reinterpret_cast<uint64_t*>(&write_data_[0]);
+    std::vector<PlatformHandle> duplicated_handles(count);
+    for (uint32_t i = 0; i < count; ++i) {
+      duplicated_handles[i] =
+          PlatformHandle(DuplicateFromChild(message->handles[i]));
+    }
+    ParentTokenSerializerState::GetInstance()->HandleToToken(
+        &duplicated_handles[0], count, tokens);
+  } else if (message->id == TOKEN_TO_HANDLE) {
+    uint32_t count =
+        (message->size - kTokenSerializerMessageHeaderSize) /
+        sizeof(uint64_t);
+    if (count > GetConfiguration().max_message_num_handles) {
+      NOTREACHED() << "Too many tokens from child process. Closing channel.";
+      delete this;
+      return;
+    }
+    uint32_t response_size = count * sizeof(HANDLE);
+    write_data_.resize(response_size);
+    HANDLE* handles = reinterpret_cast<HANDLE*>(&write_data_[0]);
+    std::vector<PlatformHandle> temp_handles(count);
+    ParentTokenSerializerState::GetInstance()->TokenToHandle(
+        &message->tokens[0], count, &temp_handles[0]);
+    for (uint32_t i = 0; i < count; ++i) {
+      if (temp_handles[i].is_valid()) {
+        handles[i] = DuplicateToChild(temp_handles[i].handle);
+      } else {
+        NOTREACHED() << "Unknown token";
+        handles[i] = INVALID_HANDLE_VALUE;
+      }
+    }
+  } else {
+    NOTREACHED() << "Unknown command. Stopping reading.";
+    delete this;
+    return;
+  }
+
+  BOOL rv = WriteFile(pipe_.get().handle, &write_data_[0],

[yzshen1, 2015/11/20 20:39:55]

I think it is not guaranteed that the write could be finished in one shot. We
need to handle partial write just like we handle partial read.

[jam, 2015/11/21 01:26:09]

since this side uses overlapped IO (as opposed to child side which doesn't),
while it might not complete synchronously, it will complete async with that data
(i.e. return value of 0 and last error of ERROR_IO_PENDING). There isn't a
problem of reusing the write context because the other side (child) won't send
more messages till they read all their previous response.

+                      static_cast<int>(write_data_.size()), NULL,
+                      &write_context_.overlapped);
+  DCHECK(rv);
+
+  // Start reading again.
+  num_bytes_read_ = 0;
+  BeginRead();
+}
+
+
+HANDLE ParentTokenSerializer::DuplicateToChild(HANDLE handle) {
+  HANDLE rv = INVALID_HANDLE_VALUE;
+  BOOL result = DuplicateHandle(base::GetCurrentProcessHandle(), handle,
+                                child_process_, &rv, 0, FALSE,
+                                DUPLICATE_SAME_ACCESS | DUPLICATE_CLOSE_SOURCE);
+  DCHECK(result);
+  return rv;
+}
+
+HANDLE ParentTokenSerializer::DuplicateFromChild(HANDLE handle) {
+  HANDLE rv = INVALID_HANDLE_VALUE;
+  BOOL result = DuplicateHandle(child_process_, handle,
+                                base::GetCurrentProcessHandle(), &rv, 0, FALSE,
+                                DUPLICATE_SAME_ACCESS | DUPLICATE_CLOSE_SOURCE);
+  DCHECK(result);
+  return rv;
+}
+
+}  // namespace edk
+}  // namespace mojo