1 files changed, 57 insertions, 0 deletions
diff --git a/src/pkg/crypto/cipher/io.go b/src/pkg/crypto/cipher/io.go
new file mode 100644
index 000000000..97f40b8e7
--- /dev/null
+++ b/src/pkg/crypto/cipher/io.go
@@ -0,0 +1,57 @@
+// 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()
+}