Load registry hive from C# fails

Question

I am trying to load an off-line NTUSER.DAT file (and then modify it), but I cannot get this working. RegLoadKey returns 8589934592, which I have no idea what it means. This is the line that fails:

long retVal = RegLoadKey(HKEY_USERS, "123test", @"D:\temp\NTUSER.DAT");

Here is the full test code:

public class RegistryTest
{
    [StructLayout(LayoutKind.Sequential)]
    private struct LUID
    {
        public uint LowPart;
        public int HighPart;
    }

    [StructLayout(LayoutKind.Sequential)]
    private struct LUID_AND_ATTRIBUTES
    {
        public LUID pLuid;
        public UInt32 Attributes;
    }

    [StructLayout(LayoutKind.Sequential, Pack = 1)]
    private struct TokPriv1Luid
    {
        public int Count;
        public LUID Luid;
        public UInt32 Attr;
    }

    private const Int32 ANYSIZE_ARRAY = 1;
    private const UInt32 SE_PRIVILEGE_ENABLED = 0x00000002;
    private const UInt32 TOKEN_ADJUST_PRIVILEGES = 0x0020;
    private const UInt32 TOKEN_QUERY = 0x0008;

    private const uint HKEY_USERS = 0x80000003;
    private const string SE_RESTORE_NAME = "SeRestorePrivilege";
    private const string SE_BACKUP_NAME = "SeBackupPrivilege";

    [DllImport("kernel32.dll")]
    static extern IntPtr GetCurrentProcess();

    [DllImport("advapi32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    static extern bool OpenProcessToken(IntPtr ProcessHandle, UInt32 DesiredAccess, out IntPtr TokenHandle);

    [DllImport("advapi32.dll", SetLastError = true, CharSet = CharSet.Auto)]
    [return: MarshalAs(UnmanagedType.Bool)]
    static extern bool LookupPrivilegeValue(string lpSystemName, string lpName, out LUID lpLuid);

    [DllImport("advapi32.dll", ExactSpelling = true, SetLastError = true)]
    static extern bool AdjustTokenPrivileges(
        IntPtr htok,
        bool disableAllPrivileges,
        ref TokPriv1Luid newState,
        int len,
        IntPtr prev,
        IntPtr relen);

    [DllImport("advapi32.dll", SetLastError = true)]
    static extern long RegLoadKey(UInt32 hKey, String lpSubKey, String lpFile);

    [DllImport("advapi32.dll", SetLastError = true)]
    static extern long RegUnLoadKey(UInt32 hKey, string lpSubKey);

    private IntPtr _myToken;
    private TokPriv1Luid _tokenPrivileges = new TokPriv1Luid();
    private TokPriv1Luid _tokenPrivileges2 = new TokPriv1Luid();

    private LUID _restoreLuid;
    private LUID _backupLuid;

    public RegistryTest()
    {
        if (!OpenProcessToken(GetCurrentProcess(), TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY, out _myToken))
            Console.WriteLine("OpenProcess Error");

        if (!LookupPrivilegeValue(null, SE_RESTORE_NAME, out _restoreLuid))
            Console.WriteLine("LookupPrivilegeValue Error");

        if (!LookupPrivilegeValue(null, SE_BACKUP_NAME, out _backupLuid))
            Console.WriteLine("LookupPrivilegeValue Error");

        _tokenPrivileges.Attr = SE_PRIVILEGE_ENABLED;
        _tokenPrivileges.Luid = _restoreLuid;
        _tokenPrivileges.Count = 1;

        _tokenPrivileges2.Attr = SE_PRIVILEGE_ENABLED;
        _tokenPrivileges2.Luid = _backupLuid;
        _tokenPrivileges2.Count = 1;

        if (!AdjustTokenPrivileges(_myToken, false, ref _tokenPrivileges, 0, IntPtr.Zero, IntPtr.Zero))
            Console.WriteLine("AdjustTokenPrivileges Error: " + Marshal.GetLastWin32Error());

        if (!AdjustTokenPrivileges(_myToken, false, ref _tokenPrivileges2, 0, IntPtr.Zero, IntPtr.Zero))
            Console.WriteLine("AdjustTokenPrivileges Error: " + Marshal.GetLastWin32Error());

        // --> RegLoadKey fails with return value 8589934592 <--
        long retVal = RegLoadKey(HKEY_USERS, "123test", @"D:\temp\NTUSER.DAT");
        if (retVal != 0)
            Console.WriteLine("RegLoadKey Error:" + retVal);

        string test = Registry.GetValue(@"HKEY_LOCAL_MACHINE\123test\Environment", "TEMP", "") as string;
        retVal = RegUnLoadKey(HKEY_USERS, "123test");
    }
}

What am I missing? Please help!! If anyone has working C# sample code for loading a hive and modifying a value, even better.

Thanks.

Answer 1

8589934592 is 0x200000000 which is more than 32 bits long.

RegLoadKey returns a win32 "long" value, which is 32 bits. You've declared the function as returning a C# long which is 64 bits. If you fix the RegLoadKey declaration to return an int you'll get a value of 0 as expected.