base/file_descriptor_posix.h

   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
  11 namespace 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 // -----------------------------------------------------------------------------
  28 struct 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_