// 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" // 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 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 }