GetSystemWow64Directory

GetSystemWow64Directory.c

__int64 __fastcall GetSystemWow64Directory2W(LPWSTR lpBuffer, ULONG Size, WORD ImageFileMachineType)
{
  const UNICODE_STRING *usSystemDirectory; // rbx
  UINT sysDirLength; // ecx
  __int64 result; // rax
  unsigned int maxLength; // edx
  _UNICODE_STRING usQueryBuffer; // [rsp+20h] [rbp-18h] BYREF

  usQueryBuffer = 0i64;
  if ( Size > 0xFFFF )
    LOWORD(Size) = 0xFFFF;
  usQueryBuffer.Buffer = lpBuffer;
  usQueryBuffer.MaximumLength = 2 * Size;
  switch ( ImageFileMachineType )
  {
    case 1u:
      usSystemDirectory = &hostDir;             // "\\system32"
      break;
    case 0x14Cu:
      usSystemDirectory = &x86Dir;              // "\\SysWOW64"
      break;
    case 0x1C4u:
      usSystemDirectory = &armDir;              // "\\SysArm32"
      break;
    case 0x8664u:
      usSystemDirectory = &amd64Dir;            // "\\SysX8664"
      break;
    case 0xAA64u:
      usSystemDirectory = &arm64Dir;            // "\\SysArm64"
      break;
    default:
      RtlSetLastWin32Error(0xA0u);
      return 0i64;
  }
  sysDirLength = GetSystemWindowsDirectoryW(0i64, 0);
  if ( !sysDirLength )
    return 0i64;
  result = sysDirLength + (usSystemDirectory->Length >> 1);
  maxLength = usQueryBuffer.MaximumLength >> 1;
  if ( maxLength < result )
    return result;
  usQueryBuffer.Length = 2 * GetSystemWindowsDirectoryW(usQueryBuffer.Buffer, maxLength);
  if ( !usQueryBuffer.Length || RtlAppendUnicodeStringToString(&usQueryBuffer, usSystemDirectory) < 0 )
    return 0i64;
  usQueryBuffer.Buffer[usQueryBuffer.Length >> 1] = 0;
  return usQueryBuffer.Length >> 1;
}