[mojo] Add CreateSharedBuffer method to Broker.

mojo/edk/system/child_broker_host.cc

Index: mojo/edk/system/child_broker_host.cc
diff --git a/mojo/edk/system/child_broker_host.cc b/mojo/edk/system/child_broker_host.cc
index 20a73d9589e7812da2cf5348c5dece9b682269bd..916c521f76a49dbf546d86772c0df768e77bdf2f 100644
--- a/mojo/edk/system/child_broker_host.cc
+++ b/mojo/edk/system/child_broker_host.cc
@@ -12,12 +12,20 @@
 #include "base/lazy_instance.h"
 #include "mojo/edk/embedder/embedder_internal.h"
 #include "mojo/edk/embedder/platform_channel_pair.h"
+#include "mojo/edk/embedder/platform_shared_buffer.h"
+#include "mojo/edk/embedder/platform_support.h"
 #include "mojo/edk/system/broker_messages.h"
 #include "mojo/edk/system/broker_state.h"
 #include "mojo/edk/system/configuration.h"
 #include "mojo/edk/system/core.h"
 #include "mojo/edk/system/platform_handle_dispatcher.h"
 
+#if defined(OS_POSIX)
+#include <sys/uio.h>
+
+#include "mojo/edk/embedder/platform_channel_utils_posix.h"
+#endif
+
 namespace mojo {
 namespace edk {
 
@@ -29,27 +37,33 @@ static const int kDefaultReadBufferSize = 256;
 
 ChildBrokerHost::ChildBrokerHost(base::ProcessHandle child_process,
                                  ScopedPlatformHandle pipe)
-    : process_id_(base::GetProcId(child_process)), child_channel_(nullptr) {
-  ScopedPlatformHandle parent_async_channel_handle;
-#if defined(OS_POSIX)
-  parent_async_channel_handle = std::move(pipe);
-#else
+    : process_id_(base::GetProcId(child_process)),
+      child_channel_(nullptr),
+      num_bytes_read_(0) {
+  // First set up the synchronous pipe.
+  sync_channel_ = std::move(pipe);
+
+  // See comment in ChildBroker::SetChildBrokerHostHandle. Summary is we need
+  // two pipes, so send the second one over the first one.
+  PlatformChannelPair parent_pipe;
+
+  ScopedPlatformHandle parent_async_channel_handle =
+      parent_pipe.PassServerHandle();
+
+  num_bytes_read_ = 0;
+
+// Send over the async pipe.
+#if defined(OS_WIN)
   DuplicateHandle(GetCurrentProcess(), child_process,
                   GetCurrentProcess(), &child_process,
                   0, FALSE, DUPLICATE_SAME_ACCESS);
   child_process_ = base::Process(child_process);
-  sync_channel_ = pipe.Pass();
+
   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;
   read_data_.resize(kDefaultReadBufferSize);
-  num_bytes_read_ = 0;
-
-  // See comment in ChildBroker::SetChildBrokerHostHandle. Summary is we need
-  // two pipes on Windows, so send the second one over the first one.
-  PlatformChannelPair parent_pipe;
-  parent_async_channel_handle = parent_pipe.PassServerHandle();
 
   HANDLE duplicated_child_handle =
       DuplicateToChild(parent_pipe.PassClientHandle().release().handle);
@@ -57,6 +71,13 @@ ChildBrokerHost::ChildBrokerHost(base::ProcessHandle child_process,
                       &duplicated_child_handle, sizeof(duplicated_child_handle),
                       NULL, &write_context_.overlapped);
   DCHECK(rv || GetLastError() == ERROR_IO_PENDING);
+#else
+  // Send just one null byte.
+  struct iovec iov = {const_cast<char*>(""), 1};
+  PlatformHandle child_handle = parent_pipe.PassClientHandle().release();
+  ssize_t result = PlatformChannelSendmsgWithHandles(sync_channel_.get(), &iov,
+                                                     1, &child_handle, 1);
+  CHECK_NE(-1, result);
 #endif
 
   internal::g_io_thread_task_runner->PostTask(
@@ -128,6 +149,11 @@ void ChildBrokerHost::InitOnIO(
   base::MessageLoopForIO::current()->RegisterIOHandler(
       sync_channel_.get().handle, this);
   BeginRead();
+#else
+  base::MessageLoopForIO::current()->WatchFileDescriptor(
+      sync_channel_.get().handle, true, base::MessageLoopForIO::WATCH_READ,
+      &fd_controller_, this);
+  DoRead();
 #endif
 }
 
@@ -166,11 +192,8 @@ void ChildBrokerHost::OnError(Error error) {
 }
 
 void ChildBrokerHost::ChannelDestructed(RoutedRawChannel* channel) {
-  // On Windows, we have two pipes to the child process. It's easier to wait
+  // We have two pipes to the child process. It's easier to wait
   // until we get the error from the pipe that is used for synchronous I/O.
-#if !defined(OS_WIN)
-  delete this;
-#endif
 }
 
 #if defined(OS_WIN)
@@ -310,6 +333,100 @@ HANDLE ChildBrokerHost::DuplicateFromChild(HANDLE handle) {
   DCHECK(result);
   return rv;
 }
+#else
+void ChildBrokerHost::DoRead() {
+  // Grab as many messages as we can before we would start blocking.
+  while (1) {
+    // Try to at least read the size of the message.
+    if (read_data_.size() < sizeof(uint32_t))
+      read_data_.resize(sizeof(uint32_t));
+    DCHECK_LT(num_bytes_read_, read_data_.size());
+
+    std::deque<PlatformHandle> dummy;
+    ssize_t bytes_read = PlatformChannelRecvmsg(
+        sync_channel_.get(), &read_data_[num_bytes_read_],
+        static_cast<int>(read_data_.size() - num_bytes_read_), &dummy);
+    DCHECK(dummy.empty());
+
+    // Connection closed.
+    if (bytes_read == 0 ||
+        (bytes_read == -1 && errno != EAGAIN && errno != EWOULDBLOCK)) {
+      delete this;
+      return;
+    }
+
+    // No more data.
+    if (bytes_read == -1)
+      break;
+
+    num_bytes_read_ += bytes_read;
+
+    // We don't know how big the message is yet.
+    if (num_bytes_read_ < sizeof(uint32_t))
+      continue;
+
+    BrokerMessage* message = reinterpret_cast<BrokerMessage*>(&read_data_[0]);

[Anand Mistry (off Chromium), 2016/01/07 04:36:33]

read_data_.data()

[Eliot Courtney, 2016/01/07 05:01:30]

Done.

+
+    // Message not done yet.
+    if (num_bytes_read_ < message->size) {
+      read_data_.resize(message->size);
+      continue;
+    }
+
+    if (num_bytes_read_ >= message->size) {
+      if (message->id == CREATE_SHARED_BUFFER) {
+        scoped_refptr<PlatformSharedBuffer> shared_buffer =
+            internal::g_platform_support->CreateSharedBuffer(
+                message->num_bytes);
+        if (shared_buffer) {
+          write_handles_.push_back(
+              shared_buffer->PassPlatformHandle().release());
+        } else {
+          LOG(ERROR)
+              << "ChildBrokerHost failed to create shared buffer of size "
+              << message->num_bytes;
+          write_handles_.emplace_back();
+        }
+
+      } else {
+        NOTREACHED() << "Unknown command. Stopping reading.";
+        delete this;
+        return;
+      }
+
+      num_bytes_read_ -= message->size;
+    }
+  }
+
+  DoWrite();
+}
+
+void ChildBrokerHost::DoWrite() {
+  while (!write_handles_.empty()) {
+    // Send just one null byte.
+    struct iovec iov = {const_cast<char*>(""), 1};
+    PlatformHandle handle = write_handles_.front();
+    ssize_t result = PlatformChannelSendmsgWithHandles(sync_channel_.get(),
+                                                       &iov, 1, &handle, 1);
+    if (result == -1)
+      break;
+    write_handles_.pop_front();
+  }
+}
+
+void ChildBrokerHost::OnFileCanReadWithoutBlocking(int fd) {
+  DCHECK(internal::g_io_thread_task_runner->RunsTasksOnCurrentThread());
+  if (fd != sync_channel_.get().handle) {
+    NOTREACHED() << "ChildBrokerHost shouldn't get notifications about file "
+                    "descriptors other than sync_channel_'s";
+    delete this;
+    return;
+  }
+
+  DoRead();
+}
+
+void ChildBrokerHost::OnFileCanWriteWithoutBlocking(int fd) {}
 #endif
 
 }  // namespace edk