Send debug output to a file

src/engine/Utils.cpp

+#include "stdafx.h"
+#include "Utils.h"
+
+namespace
+{
+  static std::wstring appDataPath;
+
+  bool IsWindowsVistaOrLater()
+  {
+    OSVERSIONINFOEX osvi;
+    ZeroMemory(&osvi, sizeof(OSVERSIONINFOEX));
+    osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFOEX);
+    GetVersionEx(reinterpret_cast<LPOSVERSIONINFO>(&osvi));
+    return osvi.dwMajorVersion >= 6;
+  }
+}
+
+std::wstring GetAppDataPath()
+{
+  if (appDataPath.empty())
+  {
+    if (IsWindowsVistaOrLater())
+    {
+      WCHAR* pathBuffer;
+      if (FAILED(SHGetKnownFolderPath(FOLDERID_LocalAppDataLow, 0, 0, &pathBuffer)))
+        throw std::runtime_error("Unable to find app data directory");
+      appDataPath.assign(pathBuffer);
+      CoTaskMemFree(pathBuffer);
+    }
+    else
+    {
+      std::auto_ptr<wchar_t> pathBuffer(new wchar_t[MAX_PATH]);
+      if (!SHGetSpecialFolderPath(0, pathBuffer.get(), CSIDL_LOCAL_APPDATA, true))
+        throw std::runtime_error("Unable to find app data directory");
+      appDataPath.assign(pathBuffer.get());
+    }
+    appDataPath += L"\\AdblockPlus";
+  }
+  return appDataPath;
+}