"Jani Järvinen [MVP]" wrote:

> Hi Roy,
>
> > If I start my program from a map drive, how do I get the local path or UNC
> > path for the application instead of the one from a map drive? I am using
> > C#.
>
> This is a bit tricky because at least I'm not aware of any classes/methods
> in .NET class library that would do this for you. Instead, you need to call
> the Win32 API function WNetGetUniversalName, but .NET's P/Invoke makes this
> easy for the programmer.
>
> Here's the definition for the said API function in C#:
>
> -----------------
> [DllImport("mpr.dll")]
> public static extern int WNetGetUniversalName(
>   string lpLocalPath,
>   int dwInfoLevel,
>   ref StringBuilder lpBuffer,
>   ref int lpBufferSize);
> -----------------
>
> Then, you can write a wrapper around this function for instance like this:
>
> -----------------
> const int UNIVERSAL_NAME_INFO_LEVEL = 1;
> const int ERROR_MORE_DATA = 234;
>
> public string ConvertLocalPathToUnc(
>   string localPath)
> {
>   StringBuilder buffer = new StringBuilder();
>   int size = 0;
>   int retVal = WNetGetUniversalName(
>     localPath, UNIVERSAL_NAME_INFO_LEVEL,
>     ref buffer, ref size);
>   if (retVal == ERROR_MORE_DATA)
>   {
>     buffer = new StringBuilder(size);
>     retVal = WNetGetUniversalName(
>       localPath, UNIVERSAL_NAME_INFO_LEVEL,
>       ref buffer, ref size);
>     if (retVal != 0)
>     {
>       throw new Win32Exception(retVal);
>     }
>   }
>   else
>   {
>     throw new Win32Exception(retVal);
>   }
>   return buffer.ToString();
> }
> -----------------
>
> To use the method and for example get the UNC path from the mapped drive
> U:\, do as follows:
>
> -----------------
> string localPath = "U:\\";
> string unc = ConvertLocalPathToUnc(localPath);
> MessageBox.Show(localPath + " = " + unc);
> -----------------
>
> That should do it. I also just blogged about this solution in case somebody
> is looking through the answer using Google. I couldn't find a ready-made
> solution to this problem with a few minutes of searching.
>
> --
> Regards,
>
> Mr. Jani Järvinen
> C# MVP
> Helsinki, Finland
> ja***@removethis.dystopia.fi
> http://www.saunalahti.fi/janij/
>
>
>