Initialize IPC:ChannelHandle from existing HANDLE

 1] Add a ctor to IPC:ChannelHandle that takes a pipe HANDLE.
 2] Corresponding change in Channel::ChannelImpl::CreatePipe to
    attach to the given pipe instead of creating a new one.

  Being able to hand over a pipe handle to IPC::Channel in this way has
  other advantages such as using anonymous pipes and safer connections
  between process with different level of privileges.   Here's how it
  can be done:

  Server Process:
   - Create a server pipe, anonymous pipe is fine too.
   - Server creates a client handle of pipe using CreateFile.
   - Use DuplicateHandle to duplicate this handle for the client process.
   - pass over the handle value to the client process, say using comman	line.

  Client process:
   - Simply receive the handle from the server and hand it over to
     IPC:Channel using IPC::ChannelHandle.

Apart from being more flexible, this is more secure as it removes
the 'connection window' while using names.

BUG=none
TEST=none


Review URL: http://codereview.chromium.org/9150030

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@118786 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 23 insertions, 7 deletions

diff --git a/ipc/ipc_channel_handle.h b/ipc/ipc_channel_handle.h
index ba034cc..7eceebb 100644
--- a/ipc/ipc_channel_handle.h
+++ b/ipc/ipc_channel_handle.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 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.
 
@@ -12,17 +12,24 @@
 
 #if defined(OS_POSIX)
 #include "base/file_descriptor_posix.h"
-#endif
+#elif defined(OS_WIN)
+#include <windows.h>
+#endif  // defined (OS_WIN)
 
 // On Windows, any process can create an IPC channel and others can fetch
 // it by name.  We pass around the channel names over IPC.
+// On Windows the initialization of ChannelHandle with an existing pipe
+// handle is provided for convenience.
+// NOTE: A ChannelHandle with a pipe handle Will NOT be marshalled over IPC.
+
 // On POSIX, we instead pass around handles to channel endpoints via IPC.
 // When it's time to IPC a new channel endpoint around, we send both the
 // channel name as well as a base::FileDescriptor, which is itself a special
 // type that knows how to copy a socket endpoint over IPC.
 //
-// In sum, when passing a handle to a channel over IPC, use this data structure
-// to work on both Windows and POSIX.
+// In sum, this data structure can be used to pass channel information by name
+// in both Windows and Posix. When passing a handle to a channel over IPC,
+// use this data structure only for POSIX.
 
 namespace IPC {
 
@@ -35,7 +42,9 @@ struct ChannelHandle {
   // processes with different working directories.
   ChannelHandle(const std::string& n) : name(n) {}
   ChannelHandle(const char* n) : name(n) {}
-#if defined(OS_POSIX)
+#if defined(OS_WIN)
+  explicit ChannelHandle(HANDLE h) : pipe(h) {}
+#elif defined(OS_POSIX)
   ChannelHandle(const std::string& n, const base::FileDescriptor& s)
       : name(n), socket(s) {}
 #endif  // defined(OS_POSIX)
@@ -43,8 +52,15 @@ struct ChannelHandle {
   std::string name;
 #if defined(OS_POSIX)
   base::FileDescriptor socket;
-#endif  // defined(OS_POSIX)
-
+#elif defined(OS_WIN)
+  // A simple container to automatically initialize pipe handle
+  struct PipeHandle {
+    PipeHandle() : handle(NULL) {}
+    PipeHandle(HANDLE h) : handle(h) {}
+    HANDLE handle;
+  };
+  PipeHandle pipe;
+#endif  // defined (OS_WIN)
 };
 
 }  // namespace IPC