+ StreamName string
+ Blocks []string
+ FileStreamSegments []FileStreamSegment
+ Err error
+}
+
+var escapeSeq = regexp.MustCompile(`\\([0-9]{3}|\\)`)
+
+func unescapeSeq(seq string) string {
+ if seq == `\\` {
+ return `\`
+ }
+ i, err := strconv.ParseUint(seq[1:], 8, 8)
+ if err != nil {
+ // Invalid escape sequence: can't unescape.
+ return seq
+ }
+ return string([]byte{byte(i)})
+}
+
+func UnescapeName(s string) string {
+ return escapeSeq.ReplaceAllStringFunc(s, unescapeSeq)
+}
+
+func ParseBlockLocator(s string) (b BlockLocator, err error) {
+ if !LocatorPattern.MatchString(s) {
+ err = fmt.Errorf("String \"%s\" does not match BlockLocator pattern "+
+ "\"%s\".",
+ s,
+ LocatorPattern.String())
+ } else {
+ tokens := strings.Split(s, "+")
+ var blockSize int64
+ var blockDigest blockdigest.BlockDigest
+ // We expect both of the following to succeed since LocatorPattern
+ // restricts the strings appropriately.
+ blockDigest, err = blockdigest.FromString(tokens[0])
+ if err != nil {
+ return
+ }
+ blockSize, err = strconv.ParseInt(tokens[1], 10, 0)
+ if err != nil {
+ return
+ }
+ b.Digest = blockDigest
+ b.Size = int(blockSize)
+ b.Hints = tokens[2:]
+ }
+ return
+}
+
+func parseFileStreamSegment(tok string) (ft FileStreamSegment, err error) {
+ parts := strings.SplitN(tok, ":", 3)
+ if len(parts) != 3 {
+ err = ErrInvalidToken
+ return
+ }
+ ft.SegPos, err = strconv.ParseUint(parts[0], 10, 64)
+ if err != nil {
+ return
+ }
+ ft.SegLen, err = strconv.ParseUint(parts[1], 10, 64)
+ if err != nil {
+ return
+ }
+ ft.Name = UnescapeName(parts[2])
+ return
+}
+
+func (s *ManifestStream) FileSegmentIterByName(filepath string) <-chan *FileSegment {
+ ch := make(chan *FileSegment)
+ go func() {
+ s.sendFileSegmentIterByName(filepath, ch)
+ close(ch)
+ }()
+ return ch
+}
+
+func (s *ManifestStream) sendFileSegmentIterByName(filepath string, ch chan<- *FileSegment) {
+ blockLens := make([]int, 0, len(s.Blocks))
+ // This is what streamName+"/"+fileName will look like:
+ target := "./" + filepath
+ for _, fTok := range s.FileStreamSegments {
+ wantPos := fTok.SegPos
+ wantLen := fTok.SegLen
+ name := fTok.Name
+
+ if s.StreamName+"/"+name != target {
+ continue
+ }
+ if wantLen == 0 {
+ ch <- &FileSegment{Locator: "d41d8cd98f00b204e9800998ecf8427e+0", Offset: 0, Len: 0}
+ continue
+ }
+ // Linear search for blocks containing data for this
+ // file
+ var blockPos uint64 = 0 // position of block in stream
+ for i, loc := range s.Blocks {
+ if blockPos >= wantPos+wantLen {
+ break
+ }
+ if len(blockLens) <= i {
+ blockLens = blockLens[:i+1]
+ b, err := ParseBlockLocator(loc)
+ if err != nil {
+ // Unparseable locator -> unusable
+ // stream.
+ ch <- nil
+ return
+ }
+ blockLens[i] = b.Size
+ }
+ blockLen := uint64(blockLens[i])
+ if blockPos+blockLen <= wantPos {
+ blockPos += blockLen
+ continue
+ }
+ fseg := FileSegment{
+ Locator: loc,
+ Offset: 0,
+ Len: blockLens[i],
+ }
+ if blockPos < wantPos {
+ fseg.Offset = int(wantPos - blockPos)
+ fseg.Len -= fseg.Offset
+ }
+ if blockPos+blockLen > wantPos+wantLen {
+ fseg.Len = int(wantPos+wantLen-blockPos) - fseg.Offset
+ }
+ ch <- &fseg
+ blockPos += blockLen
+ }
+ }