54 lines
1.7 KiB
Python
54 lines
1.7 KiB
Python
import marisa_trie
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import os
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import tarfile
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from aufs import is_aufs_metadata, get_deleted_prefix
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from util.tarlayerformat import TarLayerFormat
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AUFS_METADATA = u'.wh..wh.'
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AUFS_WHITEOUT = u'.wh.'
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AUFS_WHITEOUT_PREFIX_LENGTH = len(AUFS_WHITEOUT)
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class StreamLayerMerger(TarLayerFormat):
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""" Class which creates a generator of the combined TAR data for a set of Docker layers. """
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def __init__(self, layer_iterator):
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super(StreamLayerMerger, self).__init__(layer_iterator)
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self.path_trie = marisa_trie.Trie()
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self.path_encountered = []
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self.prefix_trie = marisa_trie.Trie()
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self.prefix_encountered = []
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def after_tar_layer(self, current_layer):
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# Update the tries.
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self.path_trie = marisa_trie.Trie(self.path_encountered)
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self.prefix_trie = marisa_trie.Trie(self.prefix_encountered)
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def check_tar_info(self, tar_info):
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absolute = os.path.relpath(tar_info.name.decode('utf-8'), './')
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# Skip metadata.
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if is_aufs_metadata(absolute):
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return False
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# Add any prefix of deleted paths to the prefix list.
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deleted_prefix = get_deleted_prefix(absolute)
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if deleted_prefix is not None:
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self.prefix_encountered.append(deleted_prefix)
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return False
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# Check if this file has already been encountered somewhere. If so,
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# skip it.
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ubsolute = unicode(absolute)
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if ubsolute in self.path_trie:
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return False
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# Check if this file is under a deleted path.
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for prefix in self.prefix_trie.iter_prefixes(ubsolute):
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if not os.path.relpath(ubsolute, prefix).startswith('..'):
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return False
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# Otherwise, add the path to the encountered list and return it.
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self.path_encountered.append(absolute)
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return True
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