xpcom/io/FileUtilsWin.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "FileUtilsWin.h"
   8
   9 #include <windows.h>
  10 #include <psapi.h>
  11
  12 #include "nsWindowsHelpers.h"
  13
  14 namespace {
  15
  16 // Scoped type used by HandleToFilename
  17 struct ScopedMappedViewTraits
  18 {
  19   typedef void* type;
  20   static void* empty()
  21   {
  22     return nullptr;
  23   }
  24   static void release(void* aPtr)
  25   {
  26     UnmapViewOfFile(aPtr);
  27   }
  28 };
  29 typedef mozilla::Scoped<ScopedMappedViewTraits> ScopedMappedView;
  30
  31 } // anonymous namespace
  32
  33 namespace mozilla {
  34
  35 bool
  36 HandleToFilename(HANDLE aHandle, const LARGE_INTEGER& aOffset,
  37                  nsAString& aFilename)
  38 {
  39   aFilename.Truncate();
  40   // This implementation is nice because it uses fully documented APIs that
  41   // are available on all Windows versions that we support.
  42   nsAutoHandle fileMapping(CreateFileMapping(aHandle, nullptr, PAGE_READONLY,
  43                                              0, 1, nullptr));
  44   if (!fileMapping) {
  45     return false;
  46   }
  47   ScopedMappedView view(MapViewOfFile(fileMapping, FILE_MAP_READ,
  48                                       aOffset.HighPart, aOffset.LowPart, 1));
  49   if (!view) {
  50     return false;
  51   }
  52   nsAutoString mappedFilename;
  53   DWORD len = 0;
  54   SetLastError(ERROR_SUCCESS);
  55   do {
  56     mappedFilename.SetLength(mappedFilename.Length() + MAX_PATH);
  57     len = GetMappedFileNameW(GetCurrentProcess(), view,
  58                              wwc(mappedFilename.BeginWriting()),
  59                              mappedFilename.Length());
  60   } while (!len && GetLastError() == ERROR_INSUFFICIENT_BUFFER);
  61   if (!len) {
  62     return false;
  63   }
  64   mappedFilename.Truncate(len);
  65   return NtPathToDosPath(mappedFilename, aFilename);
  66 }
  67
  68 } // namespace mozilla
  69