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