func()

in pkg/files/store/file.go [112:144]

• 26 lines of code
• 6 McCabe index (conditional complexity)

func (f *file) ReadAt(buff []byte, offset int64) (int, error) {
	fileSize, err := f.Fstat()
	if err != nil {
		return 0, err
	}

	alignedOffset := math.AlignDown(offset, int64(files.CacheBlockSize))

	if f.chunkOffset != 0 && alignedOffset != f.chunkOffset {
		f.reader.Log().Error().Err(errOnlySingleChunkAvailable).Int64("chunk", f.chunkOffset).Int64("alignedOffset", alignedOffset).Int64("requestedOffset", offset).Msg("file can only read chunk")
		return -1, errOnlySingleChunkAvailable
	}

	count := int(math.Min64(int64(files.CacheBlockSize), fileSize-alignedOffset))

	data, err := f.store.cache.GetOrCreate(f.Name, alignedOffset, count, func() ([]byte, error) {
		return files.FetchFile(f.reader, f.Name, alignedOffset, count)
	})
	if err != nil {
		f.reader.Log().Error().Err(err).Msg("readat error")
		return 0, fmt.Errorf("failed to ReadAt, path: %v, offset: %v, error: %v", f.Name, offset, err.Error())
	}

	pos := int(offset - alignedOffset)
	ret := math.Min(len(buff), len(data)-pos)
	ret = copy(buff[:ret], data[pos:pos+ret])

	if offset+int64(len(buff)) > fileSize {
		err = io.EOF
	}

	return ret, err
}