widget/windows/WindowsConsole.cpp

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "WindowsConsole.h"
   7
   8 #include <windows.h>
   9 #include <fcntl.h>
  10 #include <cstdio>
  11 #include <io.h>
  12
  13 namespace mozilla {
  14
  15 static void AssignStdHandle(const char* aPath, const char* aMode, FILE* aStream,
  16                             DWORD aStdHandle) {
  17   // Visual Studio's _fileno() returns -2 for the standard
  18   // streams if they aren't associated with an output stream.
  19   const int fd = _fileno(aStream);
  20   if (fd == -2) {
  21     freopen(aPath, aMode, aStream);
  22     return;
  23   }
  24   if (fd < 0) {
  25     return;
  26   }
  27
  28   const HANDLE handle = reinterpret_cast<HANDLE>(_get_osfhandle(fd));
  29   if (handle == INVALID_HANDLE_VALUE) {
  30     return;
  31   }
  32
  33   const HANDLE oldHandle = GetStdHandle(aStdHandle);
  34   if (handle == oldHandle) {
  35     return;
  36   }
  37
  38   SetStdHandle(aStdHandle, handle);
  39 }
  40
  41 // This code attaches the process to the appropriate console.
  42 void UseParentConsole() {
  43   if (AttachConsole(ATTACH_PARENT_PROCESS)) {
  44     // Redirect the standard streams to the existing console, but
  45     // only if they haven't been redirected to a valid file.
  46     AssignStdHandle("CONOUT$", "w", stdout, STD_OUTPUT_HANDLE);
  47     // There is no CONERR$, so use CONOUT$ for stderr as well.
  48     AssignStdHandle("CONOUT$", "w", stderr, STD_ERROR_HANDLE);
  49     AssignStdHandle("CONIN$", "r", stdin, STD_INPUT_HANDLE);
  50   }
  51 }
  52
  53 }  // namespace mozilla