go.etcd.io/etcd@v3.3.27+incompatible/pkg/ioutil/reader.go (about)

     1  // Copyright 2015 The etcd Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // Package ioutil implements I/O utility functions.
    16  package ioutil
    17  
    18  import "io"
    19  
    20  // NewLimitedBufferReader returns a reader that reads from the given reader
    21  // but limits the amount of data returned to at most n bytes.
    22  func NewLimitedBufferReader(r io.Reader, n int) io.Reader {
    23  	return &limitedBufferReader{
    24  		r: r,
    25  		n: n,
    26  	}
    27  }
    28  
    29  type limitedBufferReader struct {
    30  	r io.Reader
    31  	n int
    32  }
    33  
    34  func (r *limitedBufferReader) Read(p []byte) (n int, err error) {
    35  	np := p
    36  	if len(np) > r.n {
    37  		np = np[:r.n]
    38  	}
    39  	return r.r.Read(np)
    40  }