Donwloading image from repository verify md5

    def get(self, name, version):

        '''return a package from a name and version of pakage'''

        desc = self.db.get(name, version)

        return PackageImage(os.path.join(self.config.path, desc["md5"]), verbose=self.verbose)

        p = PackageImage(os.path.join(self.config.path, desc["md5"]), verbose=self.verbose)

        if p.md5 != desc["md5"]:

            raise Exception("Invalid package MD5")

        return p

class RepositoryConfig(object):

    '''Repository configuration container'''

import urllib2

from installsystems.tarball import Tarball

def md5sum(path):

def md5sum(path=None, fileobj=None):

    '''Compute md5 of a file'''

    if path is None and fileobj is None:

        raise ValueError("No path or fileobj specified")

    if fileobj is None:

        fileobj = uopen(path)

    m = hashlib.md5()

    m.update(open(path, "r").read())

    while True:

        buf = fileobj.read(1024 * m.block_size)

        if len(buf) == 0:

            break

        m.update(buf)

    return m.hexdigest()

def copy(source, destination, uid=None, gid=None, mode=None, timeout=None):

        return urllib2.urlopen(path)

    else:

        raise NotImplementedError

def extractdata(image, name, target, filelist=None):

    '''Extract a databall name into target

    This will be done accross a forking to allow higher performance and

    on the fly checksumming

    '''

    filename = "%s-%s%s" % (image.id, name, image.extension_data)

    if filename not in image.datas.keys():

        raise Exception("No such data tarball in %s" % image.name)

    datainfo = image.datas[filename]

    fileobject = ropen(filename)

    tarball = Tarball.open(fileobj=fileobject, mode="r|gz")

    if filelist is None:

        tarball.extractall(target)

    else:

        for f in filelist:

            tarball.extract(f, target)

    tarball.close()

    fileobject.close()