Move the original code path to its own function

src/pip/_internal/utils/unpacking.py

@@ -192,58 +192,7 @@ def untar_file(filename: str, location: str) -> None:
         try:
             data_filter = tarfile.data_filter  # type: ignore [attr-defined]
         except AttributeError:
-            # Fallback for Python without tarfile.data_filter
-
-            for member in tar.getmembers():
-                fn = member.name
-                if leading:
-                    fn = split_leading_dir(fn)[1]
-                path = os.path.join(location, fn)
-                if not is_within_directory(location, path):
-                    message = (
-                        "The tar file ({}) has a file ({}) trying to install "
-                        "outside target directory ({})"
-                    )
-                    raise InstallationError(message.format(filename, path, location))
-                if member.isdir():
-                    ensure_dir(path)
-                elif member.issym():
-                    try:
-                        tar._extract_member(member, path)
-                    except Exception as exc:
-                        # Some corrupt tar files seem to produce this
-                        # (specifically bad symlinks)
-                        logger.warning(
-                            "In the tar file %s the member %s is invalid: %s",
-                            filename,
-                            member.name,
-                            exc,
-                        )
-                        continue
-                else:
-                    try:
-                        fp = tar.extractfile(member)
-                    except (KeyError, AttributeError) as exc:
-                        # Some corrupt tar files seem to produce this
-                        # (specifically bad symlinks)
-                        logger.warning(
-                            "In the tar file %s the member %s is invalid: %s",
-                            filename,
-                            member.name,
-                            exc,
-                        )
-                        continue
-                    ensure_dir(os.path.dirname(path))
-                    assert fp is not None
-                    with open(path, "wb") as destfp:
-                        shutil.copyfileobj(fp, destfp)
-                    fp.close()
-                    # Update the timestamp (useful for cython compiled files)
-                    tar.utime(member, path)
-                    # member have any execute permissions for user/group/world?
-                    if member.mode & 0o111:
-                        set_extracted_file_to_default_mode_plus_executable(path)
-
+            _untar_without_filter(filename, location, tar, leading)
         else:
             default_mode_plus_executable = _get_default_mode_plus_executable()
 
@@ -277,6 +226,63 @@ def untar_file(filename: str, location: str) -> None:
     finally:
         tar.close()
 
+def _untar_without_filter(
+    filename: str,
+    location: str,
+    tar: tarfile.TarFile,
+    leading: bool,
+) -> None:
+    """Fallback for Python without tarfile.data_filter"""
+    for member in tar.getmembers():
+        fn = member.name
+        if leading:
+            fn = split_leading_dir(fn)[1]
+        path = os.path.join(location, fn)
+        if not is_within_directory(location, path):
+            message = (
+                "The tar file ({}) has a file ({}) trying to install "
+                "outside target directory ({})"
+            )
+            raise InstallationError(message.format(filename, path, location))
+        if member.isdir():
+            ensure_dir(path)
+        elif member.issym():
+            try:
+                tar._extract_member(member, path)
+            except Exception as exc:
+                # Some corrupt tar files seem to produce this
+                # (specifically bad symlinks)
+                logger.warning(
+                    "In the tar file %s the member %s is invalid: %s",
+                    filename,
+                    member.name,
+                    exc,
+                )
+                continue
+        else:
+            try:
+                fp = tar.extractfile(member)
+            except (KeyError, AttributeError) as exc:
+                # Some corrupt tar files seem to produce this
+                # (specifically bad symlinks)
+                logger.warning(
+                    "In the tar file %s the member %s is invalid: %s",
+                    filename,
+                    member.name,
+                    exc,
+                )
+                continue
+            ensure_dir(os.path.dirname(path))
+            assert fp is not None
+            with open(path, "wb") as destfp:
+                shutil.copyfileobj(fp, destfp)
+            fp.close()
+            # Update the timestamp (useful for cython compiled files)
+            tar.utime(member, path)
+            # member have any execute permissions for user/group/world?
+            if member.mode & 0o111:
+                set_extracted_file_to_default_mode_plus_executable(path)
+
 
 def unpack_file(
     filename: str,