Merge pull request #2338 from jku/hash-prefix

Add TargetFile.get_prefixed_paths()

Author: Lukas Pühringer

tests/test_api.py

@@ -725,6 +725,34 @@ def test_targetfile_from_data(self) -> None:
         targetfile_from_data = TargetFile.from_data(target_file_path, data)
         targetfile_from_data.verify_length_and_hashes(data)
 
+    def test_targetfile_get_prefixed_paths(self) -> None:
+        target = TargetFile(100, {"sha256": "abc", "md5": "def"}, "a/b/f.ext")
+        self.assertEqual(
+            target.get_prefixed_paths(), ["a/b/abc.f.ext", "a/b/def.f.ext"]
+        )
+
+        target = TargetFile(100, {"sha256": "abc", "md5": "def"}, "")
+        self.assertEqual(target.get_prefixed_paths(), ["abc.", "def."])
+
+        target = TargetFile(100, {"sha256": "abc", "md5": "def"}, "a/b/")
+        self.assertEqual(target.get_prefixed_paths(), ["a/b/abc.", "a/b/def."])
+
+        target = TargetFile(100, {"sha256": "abc", "md5": "def"}, "f.ext")
+        self.assertEqual(
+            target.get_prefixed_paths(), ["abc.f.ext", "def.f.ext"]
+        )
+
+        target = TargetFile(100, {"sha256": "abc", "md5": "def"}, "a/b/.ext")
+        self.assertEqual(
+            target.get_prefixed_paths(), ["a/b/abc..ext", "a/b/def..ext"]
+        )
+
+        target = TargetFile(100, {"sha256": "abc"}, "/root/file.ext")
+        self.assertEqual(target.get_prefixed_paths(), ["/root/abc.file.ext"])
+
+        target = TargetFile(100, {"sha256": "abc"}, "/")
+        self.assertEqual(target.get_prefixed_paths(), ["/abc."])
+
     def test_is_delegated_role(self) -> None:
         # test path matches
         # see more extensive tests in test_is_target_in_pathpattern()

tuf/api/metadata.py

@@ -1737,6 +1737,17 @@ def verify_length_and_hashes(self, data: Union[bytes, IO[bytes]]) -> None:
         self._verify_length(data, self.length)
         self._verify_hashes(data, self.hashes)
 
+    def get_prefixed_paths(self) -> List[str]:
+        """
+        Return hash-prefixed URL path fragments for the target file path.
+        """
+        paths = []
+        parent, sep, name = self.path.rpartition("/")
+        for hash_value in self.hashes.values():
+            paths.append(f"{parent}{sep}{hash_value}.{name}")
+
+        return paths
+
 
 class Targets(Signed):
     """A container for the signed part of targets metadata.