Function NewReaderFromFile

docker/internal/tarfile/reader.go:30–52

NewReaderFromFile returns a Reader for the specified path. The caller should call .Close() on the returned archive when done.

(sys *types.SystemContext, path string)

// NewReaderFromFile returns a Reader for the specified path.
// The caller should call .Close() on the returned archive when done.
func NewReaderFromFile(sys *types.SystemContext, path string) (*Reader, error) {
	file, err := os.Open(path)
	if err != nil {
		return nil, fmt.Errorf("opening file %q: %w", path, err)
	}
	defer file.Close()

	// If the file is seekable and already not compressed we can just return the file itself
	// as a source. Otherwise we pass the stream to NewReaderFromStream.
	var stream io.Reader = file
	if _, err := file.Seek(0, io.SeekCurrent); err == nil { // seeking is possible
		decompressed, isCompressed, err := compression.AutoDecompress(file)
		if err != nil {
			return nil, fmt.Errorf("detecting compression for file %q: %w", path, err)
		}
		defer decompressed.Close()
		stream = decompressed
		if !isCompressed {
			return newReader(path, false)
		}
	}
	return NewReaderFromStream(sys, stream)
}

// NewReaderFromStream returns a Reader for the specified inputStream,
// which can be either compressed or uncompressed. The caller can close the