Hooking MHTML generation to the browser.

ipc/ipc_platform_file.cc

+// Copyright (c) 2011 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 "ipc/ipc_platform_file.h"
+
+namespace IPC {
+
+PlatformFileForTransit GetFileHandleForProcess(base::PlatformFile handle,
+                                               base::ProcessHandle process,
+                                               bool close_source_handle) {
+  IPC::PlatformFileForTransit out_handle;
+#if defined(OS_WIN)
+  DWORD options = DUPLICATE_SAME_ACCESS;
+  if (close_source_handle)
+    options |= DUPLICATE_CLOSE_SOURCE;
+  if (!::DuplicateHandle(::GetCurrentProcess(),
+                         handle,
+                         process,
+                         &out_handle,
+                         0,
+                         FALSE,
+                         options)) {
+    out_handle = IPC::InvalidPlatformFileForTransit();
+  }
+#elif defined(OS_POSIX)
+  // If asked to close the source, we can simply re-use the source fd instead of
+  // dup()ing and close()ing.

[brettw, 2011/06/14 15:17:24]

Can you add to this comment, I had to ask Antoine why we needed the dup(): "When
we're not closing the source, we need to duplicate the handle and take ownership
of that. The reason is that this function is often used to generate IPC
messages, and the handle must remain valid until it's sent to the other process
from the I/O thread. Without the dup, calling code might close the source handle
before the message is sent, creating a race condition."

+  int fd = close_source_handle ? handle : ::dup(handle);
+  out_handle = base::FileDescriptor(fd, true);
+#else
+  #error Not implemented.
+#endif
+  return out_handle;
+}
+
+}  // namespace IPC