ipc/ipc_platform_file.cc

   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
  11 namespace IPC {
  12
  13 PlatformFileForTransit 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
  48 PlatformFileForTransit TakeFileHandleForProcess(base::File file,
  49                                                 base::ProcessHandle process) {
  50   return GetFileHandleForProcess(file.TakePlatformFile(), process, true);
  51 }
  52
  53 }  // namespace IPC