package idxfile import ( "crypto/sha1" "hash" "io" "sort" "gopkg.in/src-d/go-git.v4/utils/binary" ) // Encoder writes Idxfile structs to an output stream. type Encoder struct { io.Writer hash hash.Hash } // NewEncoder returns a new stream encoder that writes to w. func NewEncoder(w io.Writer) *Encoder { h := sha1.New() mw := io.MultiWriter(w, h) return &Encoder{mw, h} } // Encode encodes an Idxfile to the encoder writer. func (e *Encoder) Encode(idx *Idxfile) (int, error) { idx.Entries.Sort() flow := []func(*Idxfile) (int, error){ e.encodeHeader, e.encodeFanout, e.encodeHashes, e.encodeCRC32, e.encodeOffsets, e.encodeChecksums, } sz := 0 for _, f := range flow { i, err := f(idx) sz += i if err != nil { return sz, err } } return sz, nil } func (e *Encoder) encodeHeader(idx *Idxfile) (int, error) { c, err := e.Write(idxHeader) if err != nil { return c, err } return c + 4, binary.WriteUint32(e, idx.Version) } func (e *Encoder) encodeFanout(idx *Idxfile) (int, error) { fanout := idx.calculateFanout() for _, c := range fanout { if err := binary.WriteUint32(e, c); err != nil { return 0, err } } return 1024, nil } func (e *Encoder) encodeHashes(idx *Idxfile) (int, error) { sz := 0 for _, ent := range idx.Entries { i, err := e.Write(ent.Hash[:]) sz += i if err != nil { return sz, err } } return sz, nil } func (e *Encoder) encodeCRC32(idx *Idxfile) (int, error) { sz := 0 for _, ent := range idx.Entries { err := binary.Write(e, ent.CRC32) sz += 4 if err != nil { return sz, err } } return sz, nil } func (e *Encoder) encodeOffsets(idx *Idxfile) (int, error) { sz := 0 for _, ent := range idx.Entries { if err := binary.WriteUint32(e, uint32(ent.Offset)); err != nil { return sz, err } sz += 4 } return sz, nil } func (e *Encoder) encodeChecksums(idx *Idxfile) (int, error) { if _, err := e.Write(idx.PackfileChecksum[:]); err != nil { return 0, err } copy(idx.IdxChecksum[:], e.hash.Sum(nil)[:20]) if _, err := e.Write(idx.IdxChecksum[:]); err != nil { return 0, err } return 40, nil } // EntryList implements sort.Interface allowing sorting in increasing order. type EntryList []Entry func (p EntryList) Len() int { return len(p) } func (p EntryList) Less(i, j int) bool { return p[i].Hash.String() < p[j].Hash.String() } func (p EntryList) Swap(i, j int) { p[i], p[j] = p[j], p[i] } func (p EntryList) Sort() { sort.Sort(p) }