readcloser.go

Documentation: go.etcd.io/etcd/pkg/v3/ioutil

     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
    16  
    17  import (
    18  	"fmt"
    19  	"io"
    20  )
    21  
    22  // ReaderAndCloser implements io.ReadCloser interface by combining
    23  // reader and closer together.
    24  type ReaderAndCloser struct {
    25  	io.Reader
    26  	io.Closer
    27  }
    28  
    29  var (
    30  	ErrShortRead = fmt.Errorf("ioutil: short read")
    31  	ErrExpectEOF = fmt.Errorf("ioutil: expect EOF")
    32  )
    33  
    34  // NewExactReadCloser returns a ReadCloser that returns errors if the underlying
    35  // reader does not read back exactly the requested number of bytes.
    36  func NewExactReadCloser(rc io.ReadCloser, totalBytes int64) io.ReadCloser {
    37  	return &exactReadCloser{rc: rc, totalBytes: totalBytes}
    38  }
    39  
    40  type exactReadCloser struct {
    41  	rc         io.ReadCloser
    42  	br         int64
    43  	totalBytes int64
    44  }
    45  
    46  func (e *exactReadCloser) Read(p []byte) (int, error) {
    47  	n, err := e.rc.Read(p)
    48  	e.br += int64(n)
    49  	if e.br > e.totalBytes {
    50  		return 0, ErrExpectEOF
    51  	}
    52  	if e.br < e.totalBytes && n == 0 {
    53  		return 0, ErrShortRead
    54  	}
    55  	return n, err
    56  }
    57  
    58  func (e *exactReadCloser) Close() error {
    59  	if err := e.rc.Close(); err != nil {
    60  		return err
    61  	}
    62  	if e.br < e.totalBytes {
    63  		return ErrShortRead
    64  	}
    65  	return nil
    66  }
    67
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