func()

in v1storage/persistence.go [1591:1656]

• 64 lines of code
• 16 McCabe index (conditional complexity)

func (p *persistence) loadFPMappings() (fpMappings, model.Fingerprint, error) {
	fpm := fpMappings{}
	var highestMappedFP model.Fingerprint

	f, err := os.Open(p.mappingsFileName())
	if os.IsNotExist(err) {
		return fpm, 0, nil
	}
	if err != nil {
		return nil, 0, err
	}
	defer f.Close()
	r := bufio.NewReaderSize(f, fileBufSize)

	buf := make([]byte, len(mappingsMagicString))
	if _, err := io.ReadFull(r, buf); err != nil {
		return nil, 0, err
	}
	magic := string(buf)
	if magic != mappingsMagicString {
		return nil, 0, fmt.Errorf(
			"unexpected magic string, want %q, got %q",
			mappingsMagicString, magic,
		)
	}
	version, err := binary.ReadUvarint(r)
	if version != mappingsFormatVersion || err != nil {
		return nil, 0, fmt.Errorf("unknown fingerprint mappings format version, want %d", mappingsFormatVersion)
	}
	numRawFPs, err := binary.ReadUvarint(r)
	if err != nil {
		return nil, 0, err
	}
	for ; numRawFPs > 0; numRawFPs-- {
		rawFP, err := codable.DecodeUint64(r)
		if err != nil {
			return nil, 0, err
		}
		numMappings, err := binary.ReadUvarint(r)
		if err != nil {
			return nil, 0, err
		}
		mappings := make(map[string]model.Fingerprint, numMappings)
		for ; numMappings > 0; numMappings-- {
			lenMS, err := binary.ReadUvarint(r)
			if err != nil {
				return nil, 0, err
			}
			buf := make([]byte, lenMS)
			if _, err := io.ReadFull(r, buf); err != nil {
				return nil, 0, err
			}
			fp, err := codable.DecodeUint64(r)
			if err != nil {
				return nil, 0, err
			}
			mappedFP := model.Fingerprint(fp)
			if mappedFP > highestMappedFP {
				highestMappedFP = mappedFP
			}
			mappings[string(buf)] = mappedFP
		}
		fpm[model.Fingerprint(rawFP)] = mappings
	}
	return fpm, highestMappedFP, nil
}