github.com/containerd/containerd@v22.0.0-20200918172823-438c87b8e050+incompatible/content/local/readerat.go (about)

     1  /*
     2     Copyright The containerd Authors.
     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 local
    18  
    19  import (
    20  	"os"
    21  )
    22  
    23  // readerat implements io.ReaderAt in a completely stateless manner by opening
    24  // the referenced file for each call to ReadAt.
    25  type sizeReaderAt struct {
    26  	size int64
    27  	fp   *os.File
    28  }
    29  
    30  func (ra sizeReaderAt) ReadAt(p []byte, offset int64) (int, error) {
    31  	return ra.fp.ReadAt(p, offset)
    32  }
    33  
    34  func (ra sizeReaderAt) Size() int64 {
    35  	return ra.size
    36  }
    37  
    38  func (ra sizeReaderAt) Close() error {
    39  	return ra.fp.Close()
    40  }