1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "ipc/ipc_platform_file.h"
6
7#if defined(OS_POSIX)
8#include <unistd.h>
9#endif
10
11namespace IPC {
12
13PlatformFileForTransit GetFileHandleForProcess(base::PlatformFile handle,
14                                               base::ProcessHandle process,
15                                               bool close_source_handle) {
16  IPC::PlatformFileForTransit out_handle;
17#if defined(OS_WIN)
18  DWORD options = DUPLICATE_SAME_ACCESS;
19  if (close_source_handle)
20    options |= DUPLICATE_CLOSE_SOURCE;
21  if (handle == INVALID_HANDLE_VALUE ||
22      !::DuplicateHandle(::GetCurrentProcess(),
23                         handle,
24                         process,
25                         &out_handle,
26                         0,
27                         FALSE,
28                         options)) {
29    out_handle = IPC::InvalidPlatformFileForTransit();
30  }
31#elif defined(OS_POSIX)
32  // If asked to close the source, we can simply re-use the source fd instead of
33  // dup()ing and close()ing.
34  // When we're not closing the source, we need to duplicate the handle and take
35  // ownership of that. The reason is that this function is often used to
36  // generate IPC messages, and the handle must remain valid until it's sent to
37  // the other process from the I/O thread. Without the dup, calling code might
38  // close the source handle before the message is sent, creating a race
39  // condition.
40  int fd = close_source_handle ? handle : ::dup(handle);
41  out_handle = base::FileDescriptor(fd, true);
42#else
43  #error Not implemented.
44#endif
45  return out_handle;
46}
47
48PlatformFileForTransit TakeFileHandleForProcess(base::File file,
49                                                base::ProcessHandle process) {
50  return GetFileHandleForProcess(file.TakePlatformFile(), process, true);
51}
52
53}  // namespace IPC
54