package ioutils // import "github.com/docker/docker/pkg/ioutils" import "io" // NopWriter represents a type which write operation is nop. type NopWriter struct{} func (*NopWriter) Write(buf []byte) (int, error) { return len(buf), nil } type nopWriteCloser struct { io.Writer } func (w *nopWriteCloser) Close() error { return nil } // NopWriteCloser returns a nopWriteCloser. func NopWriteCloser(w io.Writer) io.WriteCloser { return &nopWriteCloser{w} } // NopFlusher represents a type which flush operation is nop. type NopFlusher struct{} // Flush is a nop operation. func (f *NopFlusher) Flush() {} type writeCloserWrapper struct { io.Writer closer func() error } func (r *writeCloserWrapper) Close() error { return r.closer() } // NewWriteCloserWrapper returns a new io.WriteCloser. func NewWriteCloserWrapper(r io.Writer, closer func() error) io.WriteCloser { return &writeCloserWrapper{ Writer: r, closer: closer, } } // WriteCounter wraps a concrete io.Writer and hold a count of the number // of bytes written to the writer during a "session". // This can be convenient when write return is masked // (e.g., json.Encoder.Encode()) type WriteCounter struct { Count int64 Writer io.Writer } // NewWriteCounter returns a new WriteCounter. func NewWriteCounter(w io.Writer) *WriteCounter { return &WriteCounter{ Writer: w, } } func (wc *WriteCounter) Write(p []byte) (count int, err error) { count, err = wc.Writer.Write(p) wc.Count += int64(count) return }