Source file src/testing/iotest/writer.go

Documentation: testing/iotest

		 1  // Copyright 2009 The Go Authors. All rights reserved.
		 2  // Use of this source code is governed by a BSD-style
		 3  // license that can be found in the LICENSE file.
		 4  
		 5  package iotest
		 6  
		 7  import "io"
		 8  
		 9  // TruncateWriter returns a Writer that writes to w
		10  // but stops silently after n bytes.
		11  func TruncateWriter(w io.Writer, n int64) io.Writer {
		12  	return &truncateWriter{w, n}
		13  }
		14  
		15  type truncateWriter struct {
		16  	w io.Writer
		17  	n int64
		18  }
		19  
		20  func (t *truncateWriter) Write(p []byte) (n int, err error) {
		21  	if t.n <= 0 {
		22  		return len(p), nil
		23  	}
		24  	// real write
		25  	n = len(p)
		26  	if int64(n) > t.n {
		27  		n = int(t.n)
		28  	}
		29  	n, err = t.w.Write(p[0:n])
		30  	t.n -= int64(n)
		31  	if err == nil {
		32  		n = len(p)
		33  	}
		34  	return
		35  }
		36  

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