github.com/timstclair/heapster@v0.20.0-alpha1/Godeps/_workspace/src/k8s.io/kubernetes/pkg/util/limitwriter/limitwriter.go (about)

     1  /*
     2  Copyright 2015 The Kubernetes Authors All rights reserved.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package limitwriter
    18  
    19  import (
    20  	"errors"
    21  	"io"
    22  )
    23  
    24  // New creates a writer that is limited to writing at most n bytes to w. This writer is not
    25  // thread safe.
    26  func New(w io.Writer, n int64) io.Writer {
    27  	return &limitWriter{
    28  		w: w,
    29  		n: n,
    30  	}
    31  }
    32  
    33  // ErrMaximumWrite is returned when all bytes have been written.
    34  var ErrMaximumWrite = errors.New("maximum write")
    35  
    36  type limitWriter struct {
    37  	w io.Writer
    38  	n int64
    39  }
    40  
    41  func (w *limitWriter) Write(p []byte) (n int, err error) {
    42  	if int64(len(p)) > w.n {
    43  		p = p[:w.n]
    44  	}
    45  	if len(p) > 0 {
    46  		n, err = w.w.Write(p)
    47  		w.n -= int64(n)
    48  	}
    49  	if w.n == 0 {
    50  		err = ErrMaximumWrite
    51  	}
    52  	return
    53  }