| // Copyright 2010 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package cipher |
| |
| import "io" |
| |
| // The Stream* objects are so simple that all their members are public. Users |
| // can create them themselves. |
| |
| // StreamReader wraps a [Stream] into an [io.Reader]. It calls XORKeyStream |
| // to process each slice of data which passes through. |
| type StreamReader struct { |
| S Stream |
| R io.Reader |
| } |
| |
| func (r StreamReader) Read(dst []byte) (n int, err error) { |
| n, err = r.R.Read(dst) |
| r.S.XORKeyStream(dst[:n], dst[:n]) |
| return |
| } |
| |
| // StreamWriter wraps a [Stream] into an io.Writer. It calls XORKeyStream |
| // to process each slice of data which passes through. If any [StreamWriter.Write] |
| // call returns short then the StreamWriter is out of sync and must be discarded. |
| // A StreamWriter has no internal buffering; [StreamWriter.Close] does not need |
| // to be called to flush write data. |
| type StreamWriter struct { |
| S Stream |
| W io.Writer |
| Err error // unused |
| } |
| |
| func (w StreamWriter) Write(src []byte) (n int, err error) { |
| c := make([]byte, len(src)) |
| w.S.XORKeyStream(c, src) |
| n, err = w.W.Write(c) |
| if n != len(src) && err == nil { // should never happen |
| err = io.ErrShortWrite |
| } |
| return |
| } |
| |
| // Close closes the underlying Writer and returns its Close return value, if the Writer |
| // is also an io.Closer. Otherwise it returns nil. |
| func (w StreamWriter) Close() error { |
| if c, ok := w.W.(io.Closer); ok { |
| return c.Close() |
| } |
| return nil |
| } |