Compare paths from the end in C#

Today at work, a colleague came to me with quite interesting problem. He needed to find out first common directory for two given paths starting from the end.

For example, for given paths like:

c:\documents and settings\some user\my files\projects\project1\initialFiles\somefiles\ and

d:\ My Projects\project1\ChangedFiles\MyFiles\

It would return ‘project1‘.

I was surprised to find out that neither System.IO.Path, nor System.IO.Directory allows you to that. Here’s simple solution I created for him.

public static string FindLastCommonParentFolder(string path1, string path2)
{
    if (string.IsNullOrEmpty(path1))
        throw new ArgumentException();
    if (string.IsNullOrEmpty(path2))
        throw new ArgumentException();
    try
    {
        //ensures that paths are valid
        path1 = Path.GetFullPath(path1);
        path2 = Path.GetFullPath(path2);
    }
    catch (PathTooLongException ex)
    { /*handle exception}*/}
    catch (ArgumentException ex)
    { /*handle exception}*/}
    catch (NotSupportedException ex)
    { /*handle exception}*/}
    catch (SecurityException ex)
    { /*handle exception}*/}
 
    if (path1 == path2)
        return path1.Substring(path1.LastIndexOf(Path.DirectorySeparatorChar));
 
    string[] folders1 = path1.Split(Path.DirectorySeparatorChar);
    string[] folders2 = path2.Split(Path.DirectorySeparatorChar);
    if (folders1.Length < 1 || folders2.Length < 1) 
        return string.Empty;
 
    for (int i = folders1.Length - 1; i >= 0; i--)
    {
        for (int j = folders2.Length - 1; j >= 0; j--)
        { 
            if(folders1[i]==folders2[j])
                return folders1[i];
        }
    }
    return string.Empty;
}