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// 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 (
"os"
"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 simply 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 os.Error) {
n, err = r.R.Read(dst)
r.S.XORKeyStream(dst[:n], dst[:n])
return
}
// StreamWriter wraps a Stream into an io.Writer. It simply calls XORKeyStream
// to process each slice of data which passes through. If any Write call
// returns short then the StreamWriter is out of sync and must be discarded.
type StreamWriter struct {
S Stream
W io.Writer
Err os.Error
}
func (w StreamWriter) Write(src []byte) (n int, err os.Error) {
if w.Err != nil {
return 0, w.Err
}
c := make([]byte, len(src))
w.S.XORKeyStream(c, src)
n, err = w.W.Write(c)
if n != len(src) {
if err == nil { // should never happen
err = io.ErrShortWrite
}
w.Err = err
}
return
}
func (w StreamWriter) Close() os.Error {
// This saves us from either requiring a WriteCloser or having a
// StreamWriterCloser.
return w.W.(io.Closer).Close()
}
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