Work in progress: Docker -> ACI conversion

formats/tarimageformatter.py

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+import tarfile
+from util.gzipwrap import GzipWrap
+
+class TarImageFormatter(object):
+  """ Base class for classes which produce a TAR containing image and layer data. """
+
+  def build_stream(self, namespace, repository, tag, synthetic_image_id, layer_json,
+                   get_image_iterator, get_layer_iterator):
+    """ Builds and streams a synthetic .tar.gz that represents the formatted TAR created by this
+        class's implementation.
+    """
+    return GzipWrap(self.stream_generator(namespace, repository, tag,
+                                             synthetic_image_id, layer_json,
+                                             get_image_iterator, get_layer_iterator))
+
+  def stream_generator(self, namespace, repository, tag, synthetic_image_id,
+                       layer_json, get_image_iterator, get_layer_iterator):
+    raise NotImplementedError
+
+  def tar_file(self, name, contents):
+    """ Returns the TAR binary representation for a file with the given name and file contents. """
+    length = len(contents)
+    tar_data = self.tar_file_header(name, length)
+    tar_data += contents
+    tar_data += self.tar_file_padding(length)
+    return tar_data
+
+  def tar_file_padding(self, length):
+    """ Returns TAR file padding for file data of the given length. """
+    if length % 512 != 0:
+      return '\0' * (512 - (length % 512))
+
+    return ''
+
+  def tar_file_header(self, name, file_size):
+    """ Returns TAR file header data for a file with the given name and size. """
+    info = tarfile.TarInfo(name=name)
+    info.type = tarfile.REGTYPE
+    info.size = file_size
+    return info.tobuf()
+
+  def tar_folder(self, name):
+    """ Returns TAR file header data for a folder with the given name. """
+    info = tarfile.TarInfo(name=name)
+    info.type = tarfile.DIRTYPE
+    return info.tobuf()