func (h *FileHeader) SetMode(mode fs.FileMode) {
	h.CreatorVersion = h.CreatorVersion&0xff | creatorUnix<<8
	h.ExternalAttrs = fileModeToUnixMode(mode) << 16

	// set MSDOS attributes too, as the original zip does.
	if mode&fs.ModeDir != 0 {
		h.ExternalAttrs |= msdosDir
	}
	if mode&0200 == 0 {
		h.ExternalAttrs |= msdosReadOnly
	}
}

// isZip64 reports whether the file size exceeds the 32 bit limit

		}

		b.uint16(uint16(len(h.Name)))
		b.uint16(uint16(len(h.Extra)))
		b.uint16(uint16(len(h.Comment)))
		b = b[4:] // skip disk number start and internal file attr (2x uint16)
		b.uint32(h.ExternalAttrs)
		if h.offset > uint32max {
			b.uint32(uint32max)
		} else {
			b.uint32(uint32(h.offset))
		}
		if _, err := w.cw.Write(buf[:]); err != nil {
			return err
		}

	filenameLen := int(b.uint16())
	extraLen := int(b.uint16())
	commentLen := int(b.uint16())
	b = b[4:] // skipped start disk number and internal attributes (2x uint16)
	f.ExternalAttrs = b.uint32()
	f.headerOffset = int64(b.uint32())
	d := make([]byte, filenameLen+extraLen+commentLen)
	if _, err := io.ReadFull(r, d); err != nil {
		return err
	}
	f.Name = string(d[:filenameLen])