How to delay load the WinFsp DLL

fspload.c

/*
 * Use the following function to delay load the WinFsp DLL
 * directly from the WinFsp installation directory.
 *
 * You will also need to update your project settings:
 * - Linker > Input > Delay Loaded DLL's: winfsp-$(PlatformTarget).dll
 *
 * Written by Bill Zissimopoulos, 2017. Released to the public domain.
 */

static inline
NTSTATUS FspLoad(PVOID *PModule)
{
#if defined(_WIN64)
#define FSP_DLLNAME                     "winfsp-x64.dll"
#else
#define FSP_DLLNAME                     "winfsp-x86.dll"
#endif
#define FSP_DLLPATH                     "bin\\" FSP_DLLNAME

    WCHAR PathBuf[MAX_PATH];
    DWORD Size;
    HKEY RegKey;
    LONG Result;
    HMODULE Module;

    if (0 != PModule)
        *PModule = 0;

    Module = LoadLibraryW(L"" FSP_DLLNAME);
    if (0 == Module)
    {
        Result = RegOpenKeyExW(HKEY_LOCAL_MACHINE, L"Software\\WinFsp",
            0, KEY_READ | KEY_WOW64_32KEY, &RegKey);
        if (ERROR_SUCCESS == Result)
        {
            Size = sizeof PathBuf - sizeof L"" FSP_DLLPATH + sizeof(WCHAR);
            Result = RegGetValueW(RegKey, 0, L"InstallDir",
                RRF_RT_REG_SZ, 0, PathBuf, &Size);
            RegCloseKey(RegKey);
        }
        if (ERROR_SUCCESS != Result)
            return STATUS_OBJECT_NAME_NOT_FOUND;

        RtlCopyMemory(PathBuf + (Size / sizeof(WCHAR) - 1), L"" FSP_DLLPATH, sizeof L"" FSP_DLLPATH);
        Module = LoadLibraryW(PathBuf);
        if (0 == Module)
            return STATUS_DLL_NOT_FOUND;
    }

    if (0 != PModule)
        *PModule = Module;

    return STATUS_SUCCESS;

#undef FSP_DLLNAME
#undef FSP_DLLPATH
}