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Mostly changes from PR #321

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This commit is contained in:
Vladimir Diaz 2016-03-01 13:24:17 -05:00
parent 1b549919ae
commit 30f5d398f7
1 changed files with 61 additions and 50 deletions
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111
tuf/client/updater.py
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@ -608,7 +608,6 @@ def refresh(self, unsafely_update_root_if_necessary=True):
# The Root role may be updated without knowing its version number if
# top-level metadata cannot be safely downloaded (e.g., keys may have been
# revoked, thus requiring a new Root file that includes the updated keys)
# and 'unsafely_update_root_if_necessary' is True.
# We use some default, but sane, upper file length for its metadata.
DEFAULT_ROOT_UPPERLENGTH = tuf.conf.DEFAULT_ROOT_REQUIRED_LENGTH
@ -1555,17 +1554,33 @@ def _update_metadata_if_changed(self, metadata_role,
# Ensure the referenced metadata has been loaded. The 'root' role may be
# updated without having 'snapshot' available.
if referenced_metadata not in self.metadata['current']:
message = 'Cannot update ' + repr(metadata_role) + ' because ' \
+ referenced_metadata + ' is missing.'
raise tuf.RepositoryError(message)
raise tuf.RepositoryError('Cannot update ' + repr(metadata_role) +
' because ' + referenced_metadata + ' is missing.')
# The referenced metadata has been loaded. Extract the new
# versioninfo for 'metadata_role' from it.
# The referenced metadata has been loaded. Extract the new versioninfo for
# 'metadata_role' from it.
else:
message = repr(metadata_role) + ' referenced in ' +\
repr(referenced_metadata)+ '. ' + repr(metadata_role)+' may be updated.'
logger.debug(message)
logger.debug(repr(metadata_role) + ' referenced in ' +
repr(referenced_metadata)+ '. ' + repr(metadata_role) +
' may be updated.')
# Extract the versioninfo of the uncompressed version of 'metadata_role'.
expected_versioninfo = self.metadata['current'][referenced_metadata] \
['meta'] \
[uncompressed_metadata_filename]
# Simply return if the metadata for 'metadata_role' has not been updated,
# according to the uncompressed metadata provided by the referenced
# metadata. The metadata is considered updated if its version number is
# strictly greater than its currently trusted version number.
if not self._versioninfo_has_been_updated(uncompressed_metadata_filename,
expected_versioninfo):
logger.info(repr(uncompressed_metadata_filename) + ' up-to-date.')
return
logger.debug('Metadata ' + repr(uncompressed_metadata_filename) + ' has changed.')
# There might be a compressed version of 'snapshot.json' or Targets
# metadata available for download. Check the 'meta' field of
# 'referenced_metadata' to see if it is listed when 'metadata_role'
@ -1581,38 +1596,22 @@ def _update_metadata_if_changed(self, metadata_role,
# decompressing a file that may be invalid or partially intact.
compression = None
# Extract the versioninfo of the uncompressed version of 'metadata_role'.
expected_versioninfo = self.metadata['current'][referenced_metadata] \
['meta'] \
[uncompressed_metadata_filename]
# Check for the availability of compressed versions of 'snapshot.json',
# 'targets.json', and delegated Targets (that also start with 'targets').
# For 'targets.json' and delegated metadata, 'referenced_metata'
# should always be 'snapshot'. 'snapshot.json' specifies all roles
# provided by a repository, including their version numbers.
if metadata_role == 'snapshot' or metadata_role.startswith('targets'):
gzip_metadata_filename = uncompressed_metadata_filename + '.gz'
if 'gzip' in self.metadata['current']['root']['compression_algorithms']:
compression = 'gzip'
logger.debug('Compressed version of ' + \
repr(uncompressed_metadata_filename) + ' is available at ' + \
repr(gzip_metadata_filename) + '.')
else:
logger.debug('Compressed version of ' + \
repr(uncompressed_metadata_filename) + ' not available.')
# Simply return if the file has not changed, according to the metadata
# about the uncompressed file provided by the referenced metadata.
if not self._versioninfo_has_changed(uncompressed_metadata_filename,
expected_versioninfo):
logger.info(repr(uncompressed_metadata_filename) + ' up-to-date.')
gzip_metadata_filename = uncompressed_metadata_filename + '.gz'
logger.debug('Compressed version of ' +
repr(uncompressed_metadata_filename) + ' is available at ' +
repr(gzip_metadata_filename) + '.')
return
logger.debug('Metadata ' + repr(uncompressed_metadata_filename) + \
' has changed.')
else:
logger.debug('Compressed version of ' +
repr(uncompressed_metadata_filename) + ' not available.')
# The file lengths of metadata are unknown, only their version numbers are
# known. Set an upper limit for the length of the downloaded file for each
@ -1659,14 +1658,15 @@ def _update_metadata_if_changed(self, metadata_role,
def _versioninfo_has_changed(self, metadata_filename, new_versioninfo):
def _versioninfo_has_been_updated(self, metadata_filename, new_versioninfo):
"""
<Purpose>
Non-public method that determines whether the current versioninfo of
'metadata_filename' differs from 'new_versioninfo'. The 'new_versioninfo'
argument should be extracted from the latest copy of the metadata that
references 'metadata_filename'. Example: 'root.json' would be referenced
by 'snapshot.json'.
'metadata_filename' is less than 'new_versioninfo' (i.e., the version
number has been incremented). The 'new_versioninfo' argument should be
extracted from the latest copy of the metadata that references
'metadata_filename'. Example: 'root.json' would be referenced by
'snapshot.json'.
'new_versioninfo' should only be 'None' if this is for updating
'root.json' without having 'snapshot.json' available.
@ -1689,11 +1689,11 @@ def _versioninfo_has_changed(self, metadata_filename, new_versioninfo):
None.
<Side Effects>
If there is no versioninfo currently loaded for 'metada_filename',
try to load it.
If there is no versioninfo currently loaded for 'metadata_filename', try
to load it.
<Returns>
Boolean. True if the versioninfo has changed, false otherwise.
Boolean. True if the versioninfo has changed, False otherwise.
"""
# If there is no versioninfo currently stored for 'metadata_filename',
@ -1763,9 +1763,10 @@ def _update_versioninfo(self, metadata_filename):
self.metadata['current']['timestamp']['version']
# When updating snapshot.json, the client either (1) has a copy of
# snapshot.json, or (2) in the process of obtaining it by first downloading
# timestamp.json. Note: Clients may have only root.json and perform a
# refresh of top-level metadata to obtain the remaining roles.
# snapshot.json, or (2) is in the process of obtaining it by first
# downloading timestamp.json. Note: Clients are allowed to have only
# root.json initially, and perform a refresh of top-level metadata to
# obtain the remaining roles.
elif metadata_filename == 'snapshot.json':
# Verify the version number of the currently trusted snapshot.json in
@ -2791,8 +2792,9 @@ def download_target(self, target, destination_directory):
<Purpose>
Download 'target' and verify it is trusted.
This will only store the file at 'destination_directory' if the downloaded
file matches the description of the file in the trusted metadata.
This will only store the file at 'destination_directory' if the
downloaded file matches the description of the file in the trusted
metadata.
<Arguments>
target:
@ -2809,6 +2811,10 @@ def download_target(self, target, destination_directory):
tuf.NoWorkingMirrorError:
If a target could not be downloaded from any of the mirrors.
Although expected to be rare, there might be OSError exceptions (except
errno.EEXIST) raised when creating the destination directory (if it
doesn't exist).
<Side Effects>
A target file is saved to the local system.
@ -2834,15 +2840,20 @@ def download_target(self, target, destination_directory):
target_file_object = self._get_target_file(target_filepath, trusted_length,
trusted_hashes)
# We acquired a target file object from a mirror. Move the file into
# place (i.e., locally to 'destination_directory'). Note: join() discards
# 'destination_directory' if 'target_path' contains a leading path separator
# (i.e., is treated as an absolute path).
# We acquired a target file object from a mirror. Move the file into place
# (i.e., locally to 'destination_directory'). Note: join() discards
# 'destination_directory' if 'target_path' contains a leading path
# separator (i.e., is treated as an absolute path).
destination = os.path.join(destination_directory,
target_filepath.lstrip(os.sep))
destination = os.path.abspath(destination)
target_dirpath = os.path.dirname(destination)
# When attempting to create the leaf directory of 'target_dirpath', ignore
# any exceptions raised if the root directory already exists. All other
# exceptions potentially thrown by os.makedirs() are re-raised.
# Note: os.makedirs can raise OSError if the leaf directory already exists
# or cannot be created.
try:
os.makedirs(target_dirpath)