How can I convert a native (NT) pathname into a Wi

Question

I'm working on reporting some information gleaned from native system APIs. (I know this is bad.... but I'm getting information that I can't get otherwise, and I have little issue with having to update my app if/when that time comes around.)

The native API returns native pathnames, as seen by ob, i.e. \SystemRoot\System32\Ntoskrnl.exe, or \??\C:\Program Files\VMWare Workstation\vstor-ws60.sys.

I can replace common prefixes, i.e.

std::wstring NtPathToWin32Path( std::wstring ntPath )
{
    if (boost::starts_with(ntPath, L"\\\\?\\"))
    {
        ntPath.erase(ntPath.begin(), ntPath.begin() + 4);
        return ntPath;
    }
    if (boost::starts_with(ntPath, L"\\??\\"))
    {
        ntPath.erase(ntPath.begin(), ntPath.begin() + 4);
    }
    if (boost::starts_with(ntPath, L"\\"))
    {
        ntPath.erase(ntPath.begin(), ntPath.begin() + 1);
    }
    if (boost::istarts_with(ntPath, L"globalroot\\"))
    {
        ntPath.erase(ntPath.begin(), ntPath.begin() + 11);
    }
    if (boost::istarts_with(ntPath, L"systemroot"))
    {
        ntPath.replace(ntPath.begin(), ntPath.begin() + 10, GetWindowsPath());
    }
    if (boost::istarts_with(ntPath, L"windows"))
    {
        ntPath.replace(ntPath.begin(), ntPath.begin() + 7, GetWindowsPath());
    }
    return ntPath;
}

TEST(Win32Path, NtPathDoubleQuestions)
{
    ASSERT_EQ(L"C:\\Example", NtPathToWin32Path(L"\\??\\C:\\Example"));
}

TEST(Win32Path, NtPathUncBegin)
{
    ASSERT_EQ(L"C:\\Example", NtPathToWin32Path(L"\\\\?\\C:\\Example"));
}

TEST(Win32Path, NtPathWindowsStart)
{
    ASSERT_EQ(GetCombinedPath(GetWindowsPath(), L"Hello\\World"), NtPathToWin32Path(L"\\Windows\\Hello\\World"));
}

TEST(Win32Path, NtPathSystemrootStart)
{
    ASSERT_EQ(GetCombinedPath(GetWindowsPath(), L"Hello\\World"), NtPathToWin32Path(L"\\SystemRoot\\Hello\\World"));
}

TEST(Win32Path, NtPathGlobalRootSystemRoot)
{
    ASSERT_EQ(GetCombinedPath(GetWindowsPath(), L"Hello\\World"), NtPathToWin32Path(L"\\globalroot\\SystemRoot\\Hello\\World"));
}

but I'd be strongly surprised if there's not some API, native or otherwise, which will convert these into Win32 path names. Does such an API exist?

Answer 1

I wrote a function that converts different types of NT device names (filenames, COM ports, network paths, etc.) into a DOS path.

There are two functions. One converts a handle into an NT path and the other one converts this NT path into a DOS path.

Have a look here: How to get name associated with open HANDLE

// "\Device\HarddiskVolume3"                                (Harddisk Drive)
// "\Device\HarddiskVolume3\Temp"                           (Harddisk Directory)
// "\Device\HarddiskVolume3\Temp\transparent.jpeg"          (Harddisk File)
// "\Device\Harddisk1\DP(1)0-0+6\foto.jpg"                  (USB stick)
// "\Device\TrueCryptVolumeP\Data\Passwords.txt"            (Truecrypt Volume)
// "\Device\Floppy0\Autoexec.bat"                           (Floppy disk)
// "\Device\CdRom1\VIDEO_TS\VTS_01_0.VOB"                   (DVD drive)
// "\Device\Serial1"                                        (real COM port)
// "\Device\USBSER000"                                      (virtual COM port)
// "\Device\Mup\ComputerName\C$\Boot.ini"                   (network drive share,  Windows 7)
// "\Device\LanmanRedirector\ComputerName\C$\Boot.ini"      (network drive share,  Windwos XP)
// "\Device\LanmanRedirector\ComputerName\Shares\Dance.m3u" (network folder share, Windwos XP)
// "\Device\Afd"                                            (internet socket)
// "\Device\Console000F"                                    (unique name for any Console handle)
// "\Device\NamedPipe\Pipename"                             (named pipe)
// "\BaseNamedObjects\Objectname"                           (named mutex, named event, named semaphore)
// "\REGISTRY\MACHINE\SOFTWARE\Classes\.txt"                (HKEY_CLASSES_ROOT\.txt)

Answer 2

See my answer to this question.

You'd need to first get a handle to the file at that path, and then get the Win32 path for the handle.

Answer 3

We do this in production code. As far as I know there is no API (public or private) that handles this. We just do some string comparisons with a few prefixes and it works for us.

Apparently there is a function named RtlNtPathNameToDosPathName() in ntdll.dll (introduced with XP?), but I have no idea what it does; I would guess it has more to do with stuff like \Device\Harddisk0, though.

I'm not sure there is really a need for such a function, though. Win32 passes paths (in the sense of CreateFile, etc) to NT; NT doesn't pass paths to Win32. So ntdll.dll doesn't really have a need to go from NT paths to Win32 paths. In the rare case where some NT query function returns a full path, any conversion function could be internal to the Win32 dll (e.g. not exported). I don't even know if they bother, as stuff like GetModuleFileName() will just return whatever path was used to load the image. I guess this is just a leaky abstraction.

Answer 4

Check this out for getting the canonical pathname in Win32. It may be helpful for you:

http://pdh11.blogspot.com/2009/05/pathcanonicalize-versus-what-it-says-on.html

Answer 5

Here's something you could try. First use NtCreateFile to open the file, volume etc. for reading. Then use the returned HANDLE to get the full path as described here.