private static HashCode buildHashedPayload(HttpRequest request) {
   HashingInputStream his = null;
   try {
     his =
         new HashingInputStream(
             Hashing.sha256(),
             request.getPayload() == null
                 ? ByteSource.empty().openStream()
                 : request.getPayload().openStream());
     ByteStreams.copy(his, ByteStreams.nullOutputStream());
     return his.hash();
   } catch (IOException e) {
     throw new HttpException("Error signing request", e);
   } finally {
     closeQuietly(his);
   }
 }
  @Override
  public String putBlob(final String containerName, final Blob blob) throws IOException {
    String blobKey = blob.getMetadata().getName();
    Payload payload = blob.getPayload();
    filesystemContainerNameValidator.validate(containerName);
    filesystemBlobKeyValidator.validate(blobKey);
    if (getDirectoryBlobSuffix(blobKey) != null) {
      return putDirectoryBlob(containerName, blob);
    }
    File outputFile = getFileForBlobKey(containerName, blobKey);
    // TODO: should we use a known suffix to filter these out during list?
    String tmpBlobName = blobKey + "-" + UUID.randomUUID();
    File tmpFile = getFileForBlobKey(containerName, tmpBlobName);
    Path tmpPath = tmpFile.toPath();
    HashingInputStream his = null;
    try {
      Files.createParentDirs(tmpFile);
      his = new HashingInputStream(Hashing.md5(), payload.openStream());
      long actualSize = Files.asByteSink(tmpFile).writeFrom(his);
      Long expectedSize = blob.getMetadata().getContentMetadata().getContentLength();
      if (expectedSize != null && actualSize != expectedSize) {
        throw new IOException(
            "Content-Length mismatch, actual: " + actualSize + " expected: " + expectedSize);
      }
      HashCode actualHashCode = his.hash();
      HashCode expectedHashCode = payload.getContentMetadata().getContentMD5AsHashCode();
      if (expectedHashCode != null && !actualHashCode.equals(expectedHashCode)) {
        throw new IOException(
            "MD5 hash code mismatch, actual: " + actualHashCode + " expected: " + expectedHashCode);
      }
      payload.getContentMetadata().setContentMD5(actualHashCode);

      if (outputFile.exists()) {
        delete(outputFile);
      }

      UserDefinedFileAttributeView view = getUserDefinedFileAttributeView(tmpPath);
      if (view != null) {
        try {
          view.write(XATTR_CONTENT_MD5, ByteBuffer.wrap(actualHashCode.asBytes()));
          writeCommonMetadataAttr(view, blob);
        } catch (IOException e) {
          logger.debug("xattrs not supported on %s", tmpPath);
        }
      }

      setBlobAccess(containerName, tmpBlobName, BlobAccess.PRIVATE);

      if (!tmpFile.renameTo(outputFile)) {
        throw new RuntimeException("Could not rename file " + tmpFile + " to " + outputFile);
      }

      return base16().lowerCase().encode(actualHashCode.asBytes());
    } catch (IOException ex) {
      if (tmpFile != null) {
        try {
          delete(tmpFile);
        } catch (IOException e) {
          logger.debug("Could not delete %s: %s", tmpFile, e);
        }
      }
      throw ex;
    } finally {
      closeQuietly(his);
      if (payload != null) {
        payload.release();
      }
    }
  }