System.Configuration.ClientSettingsStore.QuotaEnforcedStream.BeginWrite C# (CSharp) Метод

            public override IAsyncResult BeginWrite(byte[] buffer, int offset, int numBytes, 
                                                    AsyncCallback userCallback, Object stateObject) {
                if (!CanWrite) {
                    throw new NotSupportedException();
                }

                long oldLen = _originalStream.Length;
                long newLen = _originalStream.CanSeek ? _originalStream.Position + (long)numBytes : 
                                                        _originalStream.Length + (long)numBytes;
                EnsureQuota(Math.Max(oldLen, newLen));
                return _originalStream.BeginWrite(buffer, offset, numBytes, userCallback, stateObject);
            }