Function copyBuffer

http.go:2609–2638

copyBuffer is rewritten from io.copyBuffer. We do not check if src has a WriteTo method, if dst has a ReadFrom method, or if buf is empty.

(dst io.Writer, src io.Reader, buf []byte)

// copyBuffer is rewritten from io.copyBuffer. We do not check if src has a
// WriteTo method, if dst has a ReadFrom method, or if buf is empty.
func copyBuffer(dst io.Writer, src io.Reader, buf []byte) (written int64, err error) {
	for {
		nr, er := src.Read(buf)
		if nr > 0 {
			nw, ew := dst.Write(buf[0:nr])
			if nw < 0 || nr < nw {
				nw = 0
				if ew == nil {
					ew = errors.New("invalid write result")
				}
			}
			written += int64(nw)
			if ew != nil {
				err = ew
				break
			}
			if nr != nw {
				err = io.ErrShortWrite
				break
			}
		}
		if er != nil {
			if er != io.EOF {
				err = er
			}
			break
		}
	}
	return written, err
}

var copyBufPool = sync.Pool{
	New: func() any {