// NewFileReader returns a new FileReader reading the contents of fileBlobRef,
// fetching blobs from fetcher. The fileBlobRef must be of a "bytes" or "file"
// schema blob.
//
// The caller should call Close on the FileReader when done reading.
func NewFileReader(fetcher blob.SeekFetcher, fileBlobRef blob.Ref) (*FileReader, error) {
// TODO(bradfitz): make this take a blobref.FetcherAt instead?
// TODO(bradfitz): rename this into bytes reader? but for now it's still
// named FileReader, but can also read a "bytes" schema.
if !fileBlobRef.Valid() {
return nil, errors.New("schema/filereader: NewFileReader blobref invalid")
}
rsc, _, err := fetcher.Fetch(fileBlobRef)
if err != nil {
return nil, fmt.Errorf("schema/filereader: fetching file schema blob: %v", err)
}
defer rsc.Close()
ss, err := parseSuperset(rsc)
if err != nil {
return nil, fmt.Errorf("schema/filereader: decoding file schema blob: %v", err)
}
if ss.Type != "file" && ss.Type != "bytes" {
return nil, fmt.Errorf("schema/filereader: expected \"file\" or \"bytes\" schema blob, got %q", ss.Type)
}
fr, err := ss.NewFileReader(fetcher)
if err != nil {
return nil, fmt.Errorf("schema/filereader: creating FileReader for %s: %v", fileBlobRef, err)
}
return fr, nil
}
func (ss *superset) setFromBlobRef(fetcher blob.SeekFetcher, blobRef blob.Ref) error {
if !blobRef.Valid() {
return errors.New("schema/filereader: blobref invalid")
}
ss.BlobRef = blobRef
rsc, _, err := fetcher.Fetch(blobRef)
if err != nil {
return fmt.Errorf("schema/filereader: fetching schema blob %s: %v", blobRef, err)
}
defer rsc.Close()
if err = json.NewDecoder(rsc).Decode(ss); err != nil {
return fmt.Errorf("schema/filereader: decoding schema blob %s: %v", blobRef, err)
}
return nil
}