func (pk *packer) scanChunks() error {
schemaSeen := map[blob.Ref]bool{}
return pk.fr.ForeachChunk(func(schemaPath []blob.Ref, p schema.BytesPart) error {
if !p.BlobRef.Valid() {
return errors.New("sparse files are not packed")
}
if p.Offset != 0 {
// TODO: maybe care about this later, if we ever start making
// these sorts of files.
return errors.New("file uses complicated schema. not packing.")
}
pk.schemaParent[p.BlobRef] = append([]blob.Ref(nil), schemaPath...) // clone it
pk.dataSize[p.BlobRef] = uint32(p.Size)
for _, schemaRef := range schemaPath {
if schemaSeen[schemaRef] {
continue
}
schemaSeen[schemaRef] = true
pk.schemaRefs = append(pk.schemaRefs, schemaRef)
if b, err := blob.FromFetcher(pk.s, schemaRef); err != nil {
return err
} else {
pk.schemaBlob[schemaRef] = b
}
}
pk.dataRefs = append(pk.dataRefs, p.BlobRef)
return nil
})
}
func (fr *FileReader) getBlob(br blob.Ref) (*blob.Blob, error) {
if root := fr.rootReader(); root != fr {
return root.getBlob(br)
}
fr.blobmu.Lock()
last := fr.lastBlob
fr.blobmu.Unlock()
if last != nil && last.Ref() == br {
return last, nil
}
blob, err := blob.FromFetcher(fr.fetcher, br)
if err != nil {
return nil, err
}
fr.blobmu.Lock()
fr.lastBlob = blob
fr.blobmu.Unlock()
return blob, nil
}
// readerForOffset returns a ReadCloser that reads some number of bytes and then EOF
// from the provided offset. Seeing EOF doesn't mean the end of the whole file; just the
// chunk at that offset. The caller must close the ReadCloser when done reading.
func (fr *FileReader) readerForOffset(off int64) (io.ReadCloser, error) {
if debug {
log.Printf("(%p) readerForOffset %d + %d = %d", fr, fr.rootOff, off, fr.rootOff+off)
}
if off < 0 {
panic("negative offset")
}
if off >= fr.size {
return eofReader, nil
}
offRemain := off
var skipped int64
parts := fr.ss.Parts
for len(parts) > 0 && parts[0].Size <= uint64(offRemain) {
offRemain -= int64(parts[0].Size)
skipped += int64(parts[0].Size)
parts = parts[1:]
}
if len(parts) == 0 {
return eofReader, nil
}
p0 := parts[0]
var rsc types.ReadSeekCloser
var err error
switch {
case p0.BlobRef.Valid() && p0.BytesRef.Valid():
return nil, fmt.Errorf("part illegally contained both a blobRef and bytesRef")
case !p0.BlobRef.Valid() && !p0.BytesRef.Valid():
return &nZeros{int(p0.Size - uint64(offRemain))}, nil
case p0.BlobRef.Valid():
blob, err := blob.FromFetcher(fr.fetcher, p0.BlobRef)
if err != nil {
return nil, err
}
rsc = blob.Open()
case p0.BytesRef.Valid():
var ss *superset
ss, err = fr.getSuperset(p0.BytesRef)
if err != nil {
return nil, err
}
rsc, err = ss.NewFileReader(fr.fetcher)
if err == nil {
subFR := rsc.(*FileReader)
subFR.parent = fr.rootReader()
subFR.rootOff = fr.rootOff + skipped
}
}
if err != nil {
return nil, err
}
offRemain += int64(p0.Offset)
if offRemain > 0 {
newPos, err := rsc.Seek(offRemain, os.SEEK_SET)
if err != nil {
return nil, err
}
if newPos != offRemain {
panic("Seek didn't work")
}
}
return struct {
io.Reader
io.Closer
}{
io.LimitReader(rsc, int64(p0.Size)),
rsc,
}, nil
}