func()

in component/azstorage/block_blob.go [825:892]
53 lines of code
9 McCabe index (conditional complexity)

func (bb *BlockBlob) ReadToFile(name string, offset int64, count int64, fi *os.File) (err error) {
	log.Trace("BlockBlob::ReadToFile : name %s, offset : %d, count %d", name, offset, count)
	//defer exectime.StatTimeCurrentBlock("BlockBlob::ReadToFile")()

	blobClient := bb.Container.NewBlobClient(filepath.Join(bb.Config.prefixPath, name))

	downloadPtr := to.Ptr(int64(1))

	if common.MonitorBfs() {
		bb.downloadOptions.Progress = func(bytesTransferred int64) {
			trackDownload(name, bytesTransferred, count, downloadPtr)
		}
	}

	defer log.TimeTrack(time.Now(), "BlockBlob::ReadToFile", name)

	dlOpts := *bb.downloadOptions
	dlOpts.Range = blob.HTTPRange{
		Offset: offset,
		Count:  count,
	}

	_, err = blobClient.DownloadFile(context.Background(), fi, &dlOpts)

	if err != nil {
		e := storeBlobErrToErr(err)
		if e == ErrFileNotFound {
			return syscall.ENOENT
		} else {
			log.Err("BlockBlob::ReadToFile : Failed to download blob %s [%s]", name, err.Error())
			return err
		}
	} else {
		log.Debug("BlockBlob::ReadToFile : Download complete of blob %v", name)

		// store total bytes downloaded so far
		azStatsCollector.UpdateStats(stats_manager.Increment, bytesDownloaded, count)
	}

	if bb.Config.validateMD5 {
		// Compute md5 of local file
		fileMD5, err := common.GetMD5(fi)
		if err != nil {
			log.Warn("BlockBlob::ReadToFile : Failed to generate MD5 Sum for %s", name)
		} else {
			// Get latest properties from container to get the md5 of blob
			prop, err := blobClient.GetProperties(context.Background(), &blob.GetPropertiesOptions{
				CPKInfo: bb.blobCPKOpt,
			})
			if err != nil {
				log.Warn("BlockBlob::ReadToFile : Failed to get properties of blob %s [%s]", name, err.Error())
			} else {
				blobMD5 := prop.ContentMD5
				if blobMD5 == nil {
					log.Warn("BlockBlob::ReadToFile : Failed to get MD5 Sum for blob %s", name)
				} else {
					// compare md5 and fail is not match
					if !reflect.DeepEqual(fileMD5, blobMD5) {
						log.Err("BlockBlob::ReadToFile : MD5 Sum mismatch %s", name)
						return errors.New("md5 sum mismatch on download")
					}
				}
			}
		}
	}

	return nil
}