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// Copyright 2009 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 iotest
import (
"io"
"os"
)
// TruncateWriter returns a Writer that writes to w
// but stops silently after n bytes.
func TruncateWriter(w io.Writer, n int64) io.Writer {
return &truncateWriter{w, n}
}
type truncateWriter struct {
w io.Writer
n int64
}
func (t *truncateWriter) Write(p []byte) (n int, err os.Error) {
if t.n <= 0 {
return len(p), nil
}
// real write
n = len(p)
if int64(n) > t.n {
n = int(t.n)
}
n, err = t.w.Write(p[0:n])
t.n -= int64(n)
if err == nil {
n = len(p)
}
return
}
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