1// Copyright (c) 2006-2009 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#ifndef BASE_FILE_DESCRIPTOR_POSIX_H_
6#define BASE_FILE_DESCRIPTOR_POSIX_H_
7
8#include "base/files/file.h"
9#include "base/files/scoped_file.h"
10
11namespace base {
12
13// -----------------------------------------------------------------------------
14// We introduct a special structure for file descriptors in order that we are
15// able to use template specialisation to special-case their handling.
16//
17// IMPORTANT: This is primarily intended for use when sending file descriptors
18// over IPC. Even if |auto_close| is true, base::FileDescriptor does NOT close()
19// |fd| when going out of scope. Instead, a consumer of a base::FileDescriptor
20// must invoke close() on |fd| if |auto_close| is true.
21//
22// In the case of IPC, the the IPC subsystem knows to close() |fd| after sending
23// a message that contains a base::FileDescriptor if auto_close == true. On the
24// other end, the receiver must make sure to close() |fd| after it has finished
25// processing the IPC message. See the IPC::ParamTraits<> specialization in
26// ipc/ipc_message_utils.h for all the details.
27// -----------------------------------------------------------------------------
28struct FileDescriptor {
29  FileDescriptor() : fd(-1), auto_close(false) {}
30
31  FileDescriptor(int ifd, bool iauto_close) : fd(ifd), auto_close(iauto_close) {
32  }
33
34  FileDescriptor(File file) : fd(file.TakePlatformFile()), auto_close(true) {}
35  explicit FileDescriptor(ScopedFD fd) : fd(fd.release()), auto_close(true) {}
36
37  bool operator==(const FileDescriptor& other) const {
38    return (fd == other.fd && auto_close == other.auto_close);
39  }
40
41  bool operator!=(const FileDescriptor& other) const {
42    return !operator==(other);
43  }
44
45  // A comparison operator so that we can use these as keys in a std::map.
46  bool operator<(const FileDescriptor& other) const {
47    return other.fd < fd;
48  }
49
50  int fd;
51  // If true, this file descriptor should be closed after it has been used. For
52  // example an IPC system might interpret this flag as indicating that the
53  // file descriptor it has been given should be closed after use.
54  bool auto_close;
55};
56
57}  // namespace base
58
59#endif  // BASE_FILE_DESCRIPTOR_POSIX_H_
60