feat: generate hash-prefixed path names for target

Signed-off-by: Kamui <fin-kamui@pm.me>

Author: kamui-fin

tests/test_api.py

@@ -725,6 +725,12 @@ 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_hash_prefix_paths(self) -> None:
+        target = TargetFile(
+            100, {"sha256": "abc", "md5": "def"}, "public/path/file.ext"
+        )
+        self.assertEqual(sorted(target.get_prefixed_paths()), ["public/path/abc.file.ext", "public/path/def.file.ext"])
+
     def test_is_delegated_role(self) -> None:
         # test path matches
         # see more extensive tests in test_is_target_in_pathpattern()

tuf/api/metadata.py

@@ -33,6 +33,7 @@
 import io
 import logging
 import tempfile
+import pathlib
 from datetime import datetime
 from typing import (
     IO,
@@ -1737,6 +1738,14 @@ 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]:
+        paths = []
+        path = pathlib.Path(self.path)
+        name, parent = path.name, path.parent
+        for hash in self.hashes.values():
+            paths.append(str(parent.joinpath(f"{hash}.{name}")))
+        return paths
+
 
 class Targets(Signed):
     """A container for the signed part of targets metadata.