package idxfile import ( "crypto" "io" "github.com/go-git/go-git/v5/plumbing/hash" "github.com/go-git/go-git/v5/utils/binary" ) // Encoder writes MemoryIndex 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 := hash.New(crypto.SHA1) mw := io.MultiWriter(w, h) return &Encoder{mw, h} } // Encode encodes an MemoryIndex to the encoder writer. func (e *Encoder) Encode(idx *MemoryIndex) (int, error) { flow := []func(*MemoryIndex) (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 *MemoryIndex) (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 *MemoryIndex) (int, error) { for _, c := range idx.Fanout { if err := binary.WriteUint32(e, c); err != nil { return 0, err } } return fanout * 4, nil } func (e *Encoder) encodeHashes(idx *MemoryIndex) (int, error) { var size int for k := 0; k < fanout; k++ { pos := idx.FanoutMapping[k] if pos == noMapping { continue } n, err := e.Write(idx.Names[pos]) if err != nil { return size, err } size += n } return size, nil } func (e *Encoder) encodeCRC32(idx *MemoryIndex) (int, error) { var size int for k := 0; k < fanout; k++ { pos := idx.FanoutMapping[k] if pos == noMapping { continue } n, err := e.Write(idx.CRC32[pos]) if err != nil { return size, err } size += n } return size, nil } func (e *Encoder) encodeOffsets(idx *MemoryIndex) (int, error) { var size int for k := 0; k < fanout; k++ { pos := idx.FanoutMapping[k] if pos == noMapping { continue } n, err := e.Write(idx.Offset32[pos]) if err != nil { return size, err } size += n } if len(idx.Offset64) > 0 { n, err := e.Write(idx.Offset64) if err != nil { return size, err } size += n } return size, nil } func (e *Encoder) encodeChecksums(idx *MemoryIndex) (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 }