diff options
| -rw-r--r-- | Lib/test/test_zipfile.py | 3 | ||||
| -rw-r--r-- | Lib/zipfile.py | 2 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Library/2020-04-03-16-13-59.bpo-40105.hfM2c0.rst | 2 |
3 files changed, 7 insertions, 0 deletions
diff --git a/Lib/test/test_zipfile.py b/Lib/test/test_zipfile.py index 2851051..687e43d 100644 --- a/Lib/test/test_zipfile.py +++ b/Lib/test/test_zipfile.py @@ -1856,11 +1856,14 @@ class OtherTests(unittest.TestCase): self.assertEqual(zipf.comment, b"an updated comment") # check that comments are correctly shortened in append mode + # and the file is indeed truncated with zipfile.ZipFile(TESTFN,mode="w") as zipf: zipf.comment = b"original comment that's longer" zipf.writestr("foo.txt", "O, for a Muse of Fire!") + original_zip_size = os.path.getsize(TESTFN) with zipfile.ZipFile(TESTFN,mode="a") as zipf: zipf.comment = b"shorter comment" + self.assertTrue(original_zip_size > os.path.getsize(TESTFN)) with zipfile.ZipFile(TESTFN,mode="r") as zipf: self.assertEqual(zipf.comment, b"shorter comment") diff --git a/Lib/zipfile.py b/Lib/zipfile.py index 915698f..816f858 100644 --- a/Lib/zipfile.py +++ b/Lib/zipfile.py @@ -1918,6 +1918,8 @@ class ZipFile: centDirSize, centDirOffset, len(self._comment)) self.fp.write(endrec) self.fp.write(self._comment) + if self.mode == "a": + self.fp.truncate() self.fp.flush() def _fpclose(self, fp): diff --git a/Misc/NEWS.d/next/Library/2020-04-03-16-13-59.bpo-40105.hfM2c0.rst b/Misc/NEWS.d/next/Library/2020-04-03-16-13-59.bpo-40105.hfM2c0.rst new file mode 100644 index 0000000..f71a7a1 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2020-04-03-16-13-59.bpo-40105.hfM2c0.rst @@ -0,0 +1,2 @@ +ZipFile truncates files to avoid corruption when a shorter comment is provided +in append ("a") mode. Patch by Jan Mazur. |