package objfile import ( "errors" "io" "strconv" "gopkg.in/src-d/go-git.v3/core" ) var ( // ErrClosed is returned when the objfile Reader or Writer is already closed. ErrClosed = errors.New("objfile: already closed") // ErrHeader is returned when the objfile has an invalid header. ErrHeader = errors.New("objfile: invalid header") // ErrNegativeSize is returned when a negative object size is declared. ErrNegativeSize = errors.New("objfile: negative object size") ) type header struct { t core.ObjectType size int64 } func (h *header) Read(r io.Reader) error { t, err := h.readSlice(r, ' ') if err != nil { return err } h.t, err = core.ParseObjectType(string(t)) if err != nil { return err } size, err := h.readSlice(r, 0) if err != nil { return err } h.size, err = strconv.ParseInt(string(size), 10, 64) if err != nil { return ErrHeader } if h.size < 0 { return ErrNegativeSize } return nil } func (h *header) Write(w io.Writer) error { b := h.t.Bytes() b = append(b, ' ') b = append(b, []byte(strconv.FormatInt(h.size, 10))...) b = append(b, 0) _, err := w.Write(b) return err } // readSlice reads one byte at a time from r until it encounters delim or an // error. func (h *header) readSlice(r io.Reader, delim byte) ([]byte, error) { var buf [1]byte value := make([]byte, 0, 16) for { if n, err := r.Read(buf[:]); err != nil && (err != io.EOF || n == 0) { if err == io.EOF { return nil, ErrHeader } return nil, err } if buf[0] == delim { return value, nil } value = append(value, buf[0]) } }