def METHOD_NAME(self, all_tags=True, self_provides=True, *extra_tags):
    # all_tags and *extra_tags are currently ignored
    f = open(self.__path, 'rb')
    # self.magic = f.read(5)
    # if self.magic == '\375\067zXZ':
    #    self.pkgsuffix = 'pkg.tar.xz'
    fn = open('/dev/null', 'wb')
    pipe = subprocess.Popen(['tar', '-O', '-xf', self.__path, '.PKGINFO'], stdout=subprocess.PIPE, stderr=fn).stdout
    for line in pipe.readlines():
        line = line.rstrip().split(b' = ', 2)
        if len(line) == 2:
            field, value = line[0].decode('ascii'), line[1]
            self.fields.setdefault(field, []).append(value)
    if self_provides:
        prv = b'%s = %s' % (self.name(), self.fields['pkgver'][0])
        self.fields.setdefault('provides', []).append(prv)
    return self