github.com/containerd/containerd/v2@v2.0.0-rc.2/pkg/ioutil/read_closer.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 ioutil
    18  
    19  import "io"
    20  
    21  // writeCloseInformer wraps a reader with a close function.
    22  type wrapReadCloser struct {
    23  	reader *io.PipeReader
    24  	writer *io.PipeWriter
    25  }
    26  
    27  // NewWrapReadCloser creates a wrapReadCloser from a reader.
    28  // NOTE(random-liu): To avoid goroutine leakage, the reader passed in
    29  // must be eventually closed by the caller.
    30  func NewWrapReadCloser(r io.Reader) io.ReadCloser {
    31  	pr, pw := io.Pipe()
    32  	go func() {
    33  		_, _ = io.Copy(pw, r)
    34  		pr.Close()
    35  		pw.Close()
    36  	}()
    37  	return &wrapReadCloser{
    38  		reader: pr,
    39  		writer: pw,
    40  	}
    41  }
    42  
    43  // Read reads up to len(p) bytes into p.
    44  func (w *wrapReadCloser) Read(p []byte) (int, error) {
    45  	n, err := w.reader.Read(p)
    46  	if err == io.ErrClosedPipe {
    47  		return n, io.EOF
    48  	}
    49  	return n, err
    50  }
    51  
    52  // Close closes read closer.
    53  func (w *wrapReadCloser) Close() error {
    54  	w.reader.Close()
    55  	w.writer.Close()
    56  	return nil
    57  }