gecko-dev/xpcom/base/nsWindowsHelpers.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef nsWindowsHelpers_h
#define nsWindowsHelpers_h

#include <windows.h>
#include "nsAutoRef.h"
#include "nscore.h"
#include "mozilla/Assertions.h"

// ----------------------------------------------------------------------------
// Critical Section helper class
// ----------------------------------------------------------------------------

class AutoCriticalSection
{
public:
  AutoCriticalSection(LPCRITICAL_SECTION aSection)
    : mSection(aSection)
  {
    ::EnterCriticalSection(mSection);
  }
  ~AutoCriticalSection()
  {
    ::LeaveCriticalSection(mSection);
  }
private:
  LPCRITICAL_SECTION mSection;
};

template<>
class nsAutoRefTraits<HKEY>
{
public:
  typedef HKEY RawRef;
  static HKEY Void()
  {
    return nullptr;
  }

  static void Release(RawRef aFD)
  {
    if (aFD != Void()) {
      RegCloseKey(aFD);
    }
  }
};

template<>
class nsAutoRefTraits<HDC>
{
public:
  typedef HDC RawRef;
  static HDC Void()
  {
    return nullptr;
  }

  static void Release(RawRef aFD)
  {
    if (aFD != Void()) {
      ::DeleteDC(aFD);
    }
  }
};

template<>
class nsAutoRefTraits<HBRUSH>
{
public:
  typedef HBRUSH RawRef;
  static HBRUSH Void()
  {
    return nullptr;
  }

  static void Release(RawRef aFD)
  {
    if (aFD != Void()) {
      ::DeleteObject(aFD);
    }
  }
};

template<>
class nsAutoRefTraits<HRGN>
{
public:
  typedef HRGN RawRef;
  static HRGN Void()
  {
    return nullptr;
  }

  static void Release(RawRef aFD)
  {
    if (aFD != Void()) {
      ::DeleteObject(aFD);
    }
  }
};

template<>
class nsAutoRefTraits<HBITMAP>
{
public:
  typedef HBITMAP RawRef;
  static HBITMAP Void()
  {
    return nullptr;
  }

  static void Release(RawRef aFD)
  {
    if (aFD != Void()) {
      ::DeleteObject(aFD);
    }
  }
};

template<>
class nsAutoRefTraits<SC_HANDLE>
{
public:
  typedef SC_HANDLE RawRef;
  static SC_HANDLE Void()
  {
    return nullptr;
  }

  static void Release(RawRef aFD)
  {
    if (aFD != Void()) {
      CloseServiceHandle(aFD);
    }
  }
};

template<>
class nsSimpleRef<HANDLE>
{
protected:
  typedef HANDLE RawRef;

  nsSimpleRef() : mRawRef(nullptr)
  {
  }

  nsSimpleRef(RawRef aRawRef) : mRawRef(aRawRef)
  {
  }

  bool HaveResource() const
  {
    return mRawRef && mRawRef != INVALID_HANDLE_VALUE;
  }

public:
  RawRef get() const
  {
    return mRawRef;
  }

  static void Release(RawRef aRawRef)
  {
    if (aRawRef && aRawRef != INVALID_HANDLE_VALUE) {
      CloseHandle(aRawRef);
    }
  }
  RawRef mRawRef;
};


template<>
class nsAutoRefTraits<HMODULE>
{
public:
  typedef HMODULE RawRef;
  static RawRef Void()
  {
    return nullptr;
  }

  static void Release(RawRef aFD)
  {
    if (aFD != Void()) {
      FreeLibrary(aFD);
    }
  }
};


template<>
class nsAutoRefTraits<DEVMODEW*>
{
public:
  typedef DEVMODEW* RawRef;
  static RawRef Void()
  {
    return nullptr;
  }

  static void Release(RawRef aDevMode)
  {
    if (aDevMode != Void()) {
      ::HeapFree(::GetProcessHeap(), 0, aDevMode);
    }
  }
};

typedef nsAutoRef<HKEY> nsAutoRegKey;
typedef nsAutoRef<HDC> nsAutoHDC;
typedef nsAutoRef<HBRUSH> nsAutoBrush;
typedef nsAutoRef<HRGN> nsAutoRegion;
typedef nsAutoRef<HBITMAP> nsAutoBitmap;
typedef nsAutoRef<SC_HANDLE> nsAutoServiceHandle;
typedef nsAutoRef<HANDLE> nsAutoHandle;
typedef nsAutoRef<HMODULE> nsModuleHandle;
typedef nsAutoRef<DEVMODEW*> nsAutoDevMode;

namespace {

// Construct a path "<system32>\<aModule>". return false if the output buffer
// is too small.
// Note: If the system path cannot be found, or doesn't fit in the output buffer
// with the module name, we will just ignore the system path and output the
// module name alone;
// this may mean using a normal search path wherever the output is used.
bool inline
ConstructSystem32Path(LPCWSTR aModule, WCHAR* aSystemPath, UINT aSize)
{
  MOZ_ASSERT(aSystemPath);

  size_t fileLen = wcslen(aModule);
  if (fileLen >= aSize) {
    // The module name alone cannot even fit!
    return false;
  }

  size_t systemDirLen = GetSystemDirectoryW(aSystemPath, aSize);

  if (systemDirLen) {
    if (systemDirLen < aSize - fileLen) {
      // Make the system directory path terminate with a slash.
      if (aSystemPath[systemDirLen - 1] != L'\\') {
        if (systemDirLen + 1 < aSize - fileLen) {
            aSystemPath[systemDirLen] = L'\\';
            ++systemDirLen;
            // No need to re-nullptr terminate.
        } else {
          // Couldn't fit the system path with added slash.
          systemDirLen = 0;
        }
      }
    } else {
      // Couldn't fit the system path.
      systemDirLen = 0;
    }
  }

  MOZ_ASSERT(systemDirLen + fileLen < aSize);

  wcsncpy(aSystemPath + systemDirLen, aModule, fileLen);
  aSystemPath[systemDirLen + fileLen] = L'\0';
  return true;
}

HMODULE inline
LoadLibrarySystem32(LPCWSTR aModule)
{
  WCHAR systemPath[MAX_PATH + 1];
  if (!ConstructSystem32Path(aModule, systemPath, MAX_PATH + 1)) {
    return NULL;
  }
  return LoadLibraryW(systemPath);
}

}

#endif