fix: give extracted files their pack mode

scripts/ziptools.py

@@ -107,6 +107,9 @@ def safe_extract_zip(
     """
     dest = os.path.realpath(dest_dir)
     os.makedirs(dest, exist_ok=True)
+    # Reading the umask sets it; it is put back at once.
+    umask = os.umask(0)
+    os.umask(umask)
     with zipfile.ZipFile(zip_path, "r") as zf:
         members = zf.infolist()
         if len(members) > max_members:
@@ -186,6 +189,9 @@ def safe_extract_zip(
                         f"ZIP member size mismatch for {name}: "
                         f"{actual_size} != {member.file_size}"
                     )
+                # The member's own mode, else what a plain open() gives; the
+                # temporary file is private and would keep 0600 otherwise.
+                os.chmod(tmp_path, ((mode & 0o777) or 0o666) & ~umask)
                 os.replace(tmp_path, target)
                 tmp_path = ""
             finally:

tests/test_audit_regressions.py

@@ -986,6 +986,30 @@ class ArchiveSecurityRegressions(unittest.TestCase):
             with self.assertRaisesRegex(ValueError, "members"):
                 safe_extract_zip(str(archive), str(root / "out"), max_members=1)
 
+    def test_member_modes_follow_the_archive_and_the_umask(self):
+        """Every member came out 0600, the mode of its temporary file: the
+        pico8 and vox launchers the RetroDECK pack keeps 0755 lost their
+        execute bit once download.py extracted them."""
+        with tempfile.TemporaryDirectory(dir=TMP_ROOT) as directory:
+            root = Path(directory)
+            archive = self._zip_path(root)
+            program = zipfile.ZipInfo("pico8")
+            program.create_system = 3
+            program.external_attr = (stat.S_IFREG | 0o755) << 16
+            plain = zipfile.ZipInfo("bios.bin")
+            plain.create_system = 0
+            plain.external_attr = 0x20  # MS-DOS archive bit, no Unix mode
+            with zipfile.ZipFile(archive, "w") as handle:
+                handle.writestr(program, b"\x7fELF")
+                handle.writestr(plain, b"data")
+            umask = os.umask(0o022)
+            try:
+                safe_extract_zip(str(archive), str(root / "out"))
+            finally:
+                os.umask(umask)
+            self.assertEqual((root / "out" / "pico8").stat().st_mode & 0o777, 0o755)
+            self.assertEqual((root / "out" / "bios.bin").stat().st_mode & 0o777, 0o644)
+
     def test_symlink_member_is_rejected(self):
         with tempfile.TemporaryDirectory(dir=TMP_ROOT) as directory:
             root = Path(directory)