Fix large inner files with PAX format

securetar/__init__.py

@@ -196,7 +196,18 @@ def __init__(
     def __enter__(self) -> tarfile.TarFile:
         """Start context manager tarfile."""
         tar_info = tarfile.TarInfo(name=str(self._name))
-        tar_info.mtime = int(time.time())
+        if self.outer_tar.format == tarfile.PAX_FORMAT:
+            # Ensure we always set mtime as a float to force
+            # a PAX header to be written.
+            #
+            # This is necessary to
+            # handle large files as TarInfo.tobuf will try to
+            # use a shorter ustar header if we do not have at
+            # least one float in the tarinfo.
+            # https://github.com/python/cpython/blob/53b84e772cac6e4a55cebf908d6bb9c48fe254dc/Lib/tarfile.py#L1066
+            tar_info.mtime = time.time()
+        else:
+            tar_info.mtime = int(time.time())
         self.stream = _add_stream(self.outer_tar, tar_info)
         self.stream.__enter__()
         return super().__enter__()

tests/test_tar.py

@@ -8,7 +8,7 @@
 import time
 from dataclasses import dataclass
 from pathlib import Path, PurePath
-
+from unittest.mock import patch
 import pytest
 
 from securetar import (
@@ -377,7 +377,10 @@ def test_outer_tar_must_not_be_compressed(tmp_path: Path) -> None:
                 pass
 
 
-def test_tar_stream(tmp_path: Path) -> None:
+@pytest.mark.parametrize(
+    "format", [tarfile.PAX_FORMAT, tarfile.GNU_FORMAT, tarfile.USTAR_FORMAT]
+)
+def test_tar_stream(tmp_path: Path, format: int) -> None:
     # Prepare test folder
     temp_orig = tmp_path.joinpath("orig")
     fixture_data = Path(__file__).parent.joinpath("fixtures/tar_data")
@@ -386,17 +389,18 @@ def test_tar_stream(tmp_path: Path) -> None:
     # Create Tarfile
     main_tar = tmp_path.joinpath("backup.tar")
 
-    with SecureTarFile(main_tar, "w", gzip=False) as tar_file:
-        tar_info = tarfile.TarInfo(name="test.txt")
-        with _add_stream(tar_file, tar_info) as stream:
-            stream.write(b"test")
-
-    # Restore
-    temp_new = tmp_path.joinpath("new")
-    with SecureTarFile(main_tar, "r", gzip=False) as tar_file:
-        tar_file.extractall(path=temp_new)
-
-    assert temp_new.is_dir()
-    test_file = temp_new.joinpath("test.txt")
-    assert test_file.is_file()
-    assert test_file.read_bytes() == b"test"
+    with patch.object(tarfile, "DEFAULT_FORMAT", format):
+        with SecureTarFile(main_tar, "w", gzip=False) as tar_file:
+            tar_info = tarfile.TarInfo(name="test.txt")
+            with _add_stream(tar_file, tar_info) as stream:
+                stream.write(b"test")
+
+        # Restore
+        temp_new = tmp_path.joinpath("new")
+        with SecureTarFile(main_tar, "r", gzip=False) as tar_file:
+            tar_file.extractall(path=temp_new)
+
+        assert temp_new.is_dir()
+        test_file = temp_new.joinpath("test.txt")
+        assert test_file.is_file()
+        assert test_file.read_bytes() == b"test"