Tagger: t,
		}
	}
	return wrapReader{
		Reader: wrapped,
	}
}

// A Reader wraps an io.Reader and computes the
// MD5 checksum of the read content as ETag.
//
// Optionally, a Reader can also verify that
// the computed ETag matches an expected value.
// Therefore, it compares both ETags once the
// underlying io.Reader returns io.EOF.
// If the computed ETag does not match the

		}
		if bytes.Equal(tr.blk[:], zeroBlock[:]) {
			return nil, nil, io.EOF // normal EOF; exactly 2 block of zeros read
		}
		return nil, nil, ErrHeader // Zero block and then non-zero block
	}

	// Verify the header matches a known format.
	format := tr.blk.getFormat()
	if format == FormatUnknown {
		return nil, nil, ErrHeader
	}

	var p parser
	hdr := new(Header)

	// Unpack the V7 header.

	n, err := r.src.Read(p)
	r.bytesRead += int64(n)
	if r.sha256 != nil {
		r.sha256.Write(p[:n])
	}
	if r.contentHasher != nil {
		r.contentHasher.Write(p[:n])
	}

	if err == io.EOF { // Verify content SHA256, if set.
		if r.expectedMin > 0 {
			if r.bytesRead < r.expectedMin {
				return 0, SizeTooSmall{Want: r.expectedMin, Got: r.bytesRead}
			}
		}
		if r.expectedMax > 0 {

				err = ErrChecksum
			}
		}
	}
	r.err = err
	return
}

func (r *checksumReader) Close() error { return r.rc.Close() }

// findBodyOffset does the minimum work to verify the file has a header
// and returns the file body offset.
func (f *File) findBodyOffset() (int64, error) {
	var buf [fileHeaderLen]byte
	if _, err := f.zipr.ReadAt(buf[:], f.headerOffset); err != nil {
		return 0, err