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ngclient: Make sure non-versioned link in cache is up-to-date

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Even if last root version from remote is not accepted (leading to an
exception in load_root()) we should update the symlink "root.json" in
local cache to point to last good version.

Signed-off-by: Jussi Kukkonen <jkukkonen@google.com>
This commit is contained in:
Jussi Kukkonen 2025-01-03 11:33:01 +02:00
parent 4aa09ff7d5
commit 8519bb43ed
1 changed files with 39 additions and 36 deletions
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75
tuf/ngclient/updater.py
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@ -343,50 +343,53 @@ def _persist_file(self, filename: str, data: bytes) -> None:
def _load_root(self) -> None:
"""Load root metadata.
Sequentially load and persist every newer root metadata
version available, either locally or on the remote.
Sequentially load newer root metadata versions. First try to load from
local cache and if that does not work, from the remote repository.
If metadata is loaded from remote repository, store it in local cache.
"""
# Update the root role
lower_bound = self._trusted_set.root.version + 1
upper_bound = lower_bound + self.config.max_root_rotations
for next_version in range(lower_bound, upper_bound):
# look for next_version in local cache
try:
root_path = os.path.join(
self._dir, "root_history", f"{next_version}.root.json"
)
with open(root_path, "rb") as f:
self._trusted_set.update_root(f.read())
continue
except (OSError, exceptions.RepositoryError) as e:
# this root did not exist locally or is invalid
logger.debug("Local root is not valid: %s", e)
try:
for next_version in range(lower_bound, upper_bound):
# look for next_version in local cache
try:
root_path = os.path.join(
self._dir, "root_history", f"{next_version}.root.json"
)
with open(root_path, "rb") as f:
self._trusted_set.update_root(f.read())
continue
except (OSError, exceptions.RepositoryError) as e:
# this root did not exist locally or is invalid
logger.debug("Local root is not valid: %s", e)
# next_version was not found locally, try remote
try:
data = self._download_metadata(
Root.type,
self.config.root_max_length,
next_version,
)
self._trusted_set.update_root(data)
self._persist_root(next_version, data)
# next_version was not found locally, try remote
try:
data = self._download_metadata(
Root.type,
self.config.root_max_length,
next_version,
)
self._trusted_set.update_root(data)
self._persist_root(next_version, data)
except exceptions.DownloadHTTPError as exception:
if exception.status_code not in {403, 404}:
raise
# 404/403 means current root is newest available
break
# Make sure there's a non-versioned root.json
linkname = os.path.join(self._dir, "root.json")
version = self._trusted_set.root.version
current = os.path.join("root_history", f"{version}.root.json")
with contextlib.suppress(FileNotFoundError):
os.remove(linkname)
os.symlink(current, linkname)
except exceptions.DownloadHTTPError as exception:
if exception.status_code not in {403, 404}:
raise
# 404/403 means current root is newest available
break
finally:
# Make sure the non-versioned root.json links to current version
linkname = os.path.join(self._dir, "root.json")
version = self._trusted_set.root.version
current = os.path.join("root_history", f"{version}.root.json")
with contextlib.suppress(FileNotFoundError):
os.remove(linkname)
os.symlink(current, linkname)
def _load_timestamp(self) -> None:
"""Load local and remote timestamp metadata."""