Crisis.Ionic.Zip.ZipEntry.ValidateOutput C# (CSharp) Method

        private bool ValidateOutput(string basedir, Stream outstream, out string outFileName)
        {
            if (basedir != null)
            {
                // Sometimes the name on the entry starts with a slash.
                // Rather than unpack to the root of the volume, we're going to
                // drop the slash and unpack to the specified base directory.
                string f = this.FileName.Replace("\\","/");

                // workitem 11772: remove drive letter with separator
                if (f.IndexOf(':') == 1)
                    f= f.Substring(2);

                if (f.StartsWith("/"))
                    f= f.Substring(1);

                // String.Contains is not available on .NET CF 2.0

                if (_container.ZipFile.FlattenFoldersOnExtract)
                    outFileName = Path.Combine(basedir,
                                              (f.IndexOf('/') != -1) ? Path.GetFileName(f) : f);
                else
                    outFileName = Path.Combine(basedir, f);

                // workitem 10639
                outFileName = outFileName.Replace("/","\\");

                // check if it is a directory
                if ((IsDirectory) || (FileName.EndsWith("/")))
                {
                    if (!Directory.Exists(outFileName))
                    {
                        Directory.CreateDirectory(outFileName);
                        _SetTimes(outFileName, false);
                    }
                    else
                    {
                        // the dir exists, maybe we want to overwrite times.
                        if (ExtractExistingFile == ExtractExistingFileAction.OverwriteSilently)
                            _SetTimes(outFileName, false);
                    }
                    return true;  // true == all done, caller will return
                }
                return false;  // false == work to do by caller.
            }

            if (outstream != null)
            {
                outFileName = null;
                if ((IsDirectory) || (FileName.EndsWith("/")))
                {
                    // extract a directory to streamwriter?  nothing to do!
                    return true;  // true == all done!  caller can return
                }
                return false;
            }

            throw new ArgumentNullException("outstream");
        }