reproducing the failure of value.decode("utf8") in python https://github.com/akheron/cpython/blob/2.7/Lib/tarfile.py#L1393

Dockerfile

FROM fedora:latest
RUN yum install -y attr
RUN touch file
RUN setcap 'cap_setgid,cap_setuid+ep' ./file && getcap ./file

repro.sh

#!/bin/sh

set -e
cwd=$(pwd)

d=${D:-$(mktemp -d)}

if [ ${#D} -eq 0 ] ; then
        # this base image is pretty arbitrary
        docker pull fedora:latest

        # build an image with xattr info set, and tools to get the sum (of itself)
        docker build -t test_xattr .

        # produce the tar layers of this image with xattr information
        docker save test_xattr | tar -C ${d} -x
fi

export REGISTRY_DIR=${cwd}/docker-registry
if [ ! -d ${REGISTRY_DIR} ] ; then
        git clone [email protected]:dotcloud/docker-registry.git
fi

pushd ${d}
        for path in $(find . -mindepth 1 -type d) ; do
                layer="./${path}/layer.tar"
                json="./${path}/json"

                python ${cwd}/tarsum.py ${json} ${layer}
        done
popd
rm -rf ${d}

tarsum.py

#!/usr/bin/env python

import sys
import os
import traceback
sys.path.insert(0, os.getenv("REGISTRY_DIR") + '/docker_registry/lib')
sys.path.insert(0, os.getenv("REGISTRY_DIR") + '/docker_registry')
import checksums
import tarfile

def main(args):
  if len(args) < 3:
    print "%s <jsonfile> <tarfile>" % args[0]
    return
  json_file = args[1]
  tar_file = args[2]
  jh = open(json_file)
  th = open(tar_file)
  tarsum = checksums.TarSum(jh.read())
  try:
    tar = tarfile.open(mode='r|*', fileobj=th)
    for member in tar:
      tarsum.append(member, tar)
  except BaseException as e:
    print "Unexpected error:", sys.exc_info()[0]
    print sys.exc_info()
    print e
    print traceback.format_exc()
    exit(1)
    
  print tarsum.compute()

main(sys.argv)