small refactor*

pkg/cowutils/writer.go

@@ -1,39 +0,0 @@
-package cowutils
-
-import (
-	"errors"
-	"io"
-)
-
-// sectionWriter is a helper used when we need to fallback into copying data manually
-type sectionWriter struct {
-	w    io.WriterAt // target file
-	base int64       // base position in file
-	off  int64       // current relative offset
-}
-
-// Write writes & updates offset
-func (s *sectionWriter) Write(p []byte) (int, error) {
-	n, err := s.w.WriteAt(p, s.base+s.off)
-	s.off += int64(n)
-	return n, err
-}
-
-func (s *sectionWriter) Seek(offset int64, whence int) (int64, error) {
-	switch whence {
-	case io.SeekStart:
-		// nothing needed
-	case io.SeekCurrent:
-		offset += s.off
-	case io.SeekEnd:
-		// we don't support io.SeekEnd
-		fallthrough
-	default:
-		return s.off, errors.New("Seek: invalid whence")
-	}
-	if offset < 0 {
-		return s.off, errors.New("Seek: invalid offset")
-	}
-	s.off = offset
-	return offset, nil
-}