System.AppDomainSetup.NormalizePath C# (CSharp) Method

        private String NormalizePath(String path, bool useAppBase)
        {
            if(path == null)
                return null;

            if (!useAppBase)
                path = System.Security.Util.URLString.PreProcessForExtendedPathRemoval(path, false);

            int len = path.Length;
            if (len == 0)
                return null;

#if !PLATFORM_UNIX
            bool UNCpath = false;
#endif // !PLATFORM_UNIX

            if ((len > 7) &&
                (String.Compare( path, 0, "file:", 0, 5, StringComparison.OrdinalIgnoreCase) == 0)) {
                int trim;
                
                if (path[6] == '\\') {
                    if ((path[7] == '\\') || (path[7] == '/')) {

                        // Don't allow "file:\\\\", because we can't tell the difference
                        // with it for "file:\\" + "\\server" and "file:\\\" + "\localpath"
                        if ( (len > 8) && 
                             ((path[8] == '\\') || (path[8] == '/')) )
                            throw new ArgumentException(Environment.GetResourceString("Argument_InvalidPathChars"));
                        
                        // file:\\\ means local path
                        else
#if !PLATFORM_UNIX
                            trim = 8;
#else
                            // For Unix platform, trim the first 7 charcaters only.
                            // Trimming the first 8 characters will cause
                            // the root path separator to be trimmed away,
                            // and the absolute local path becomes a relative local path.
                            trim = 7;
#endif // !PLATFORM_UNIX
                    }

                    // file:\\ means remote server
                    else {
                        trim = 5;
#if !PLATFORM_UNIX
                        UNCpath = true;
#endif // !PLATFORM_UNIX
                    }
                }

                // local path
                else if (path[7] == '/')
#if !PLATFORM_UNIX
                    trim = 8;
#else
                    // For Unix platform, trim the first 7 characters only.
                    // Trimming the first 8 characters will cause
                    // the root path separator to be trimmed away,
                    // and the absolute local path becomes a relative local path.
                    trim = 7;
#endif // !PLATFORM_UNIX

                // remote
                else {
                    // file://\\remote
                    if ( (len > 8) && (path[7] == '\\') && (path[8] == '\\') )
                        trim = 7;
                    else { // file://remote
                        trim = 5;
#if !PLATFORM_UNIX
                        // Create valid UNC path by changing
                        // all occurences of '/' to '\\' in path
                        System.Text.StringBuilder winPathBuilder =
                            new System.Text.StringBuilder(len);
                        for (int i = 0; i < len; i++) {
                            char c = path[i];
                            if (c == '/')
                                winPathBuilder.Append('\\');
                            else
                                winPathBuilder.Append(c);
                        }
                        path = winPathBuilder.ToString();
#endif // !PLATFORM_UNIX
                    }
#if !PLATFORM_UNIX
                    UNCpath = true;
#endif // !PLATFORM_UNIX
                }

                path = path.Substring(trim);
                len -= trim;
            }