DockerSource: Split checksum and layers

The current implementation store in one list:
    - checksum
    - checksum type
    - file path
    - file size
However, the information about checksum and checksum type is only used
to verify the content of tarball before it is being extracted. Splitting
these into separate lists would allow us to reuse the function
untar_layers() with FileSource.

1 files changed, 10 insertions, 2 deletions

diff --git a/src/virtBootstrap/sources/docker_source.py b/src/virtBootstrap/sources/docker_source.py
index 54d8903..246356a 100644
--- a/src/virtBootstrap/sources/docker_source.py
+++ b/src/virtBootstrap/sources/docker_source.py
@@ -65,6 +65,7 @@ class DockerSource(object):
         self.images_dir = utils.get_image_dir(self.no_cache)
         self.manifest = None
         self.layers = []
+        self.checksums = []
 
         if self.username and not self.password:
             self.password = getpass.getpass()
@@ -94,9 +95,13 @@ class DockerSource(object):
             layer_digest = layer[digest_field]
             layer_size = layer['size'] if 'size' in layer else None
 
+            # Store checksums of layers
             sum_type, layer_sum = layer_digest.split(':')
+            self.checksums.append([sum_type, layer_sum])
+
+            # Store file path and size of each layer
             file_path = os.path.join(self.images_dir, layer_sum + '.tar')
-            self.layers.append([sum_type, layer_sum, file_path, layer_size])
+            self.layers.append([file_path, layer_size])
 
     def gen_valid_uri(self, uri):
         """
@@ -230,7 +235,10 @@ class DockerSource(object):
         and have valid hash sum.
         """
         self.progress("Checking cached layers", value=0, logger=logger)
-        for sum_type, sum_expected, path, _ignore in self.layers:
+        for index, checksum in enumerate(self.checksums):
+            path = self.layers[index][0]
+            sum_type, sum_expected = checksum
+
             logger.debug("Checking layer: %s", path)
             if not (os.path.exists(path)
                     and utils.checksum(path, sum_type, sum_expected)):