bpo-29435: Allow is_tarfile to take a filelike obj (GH-18090)
`is_tarfile()` now supports `name` being a file or file-like object.
diff --git a/Lib/tarfile.py b/Lib/tarfile.py
index 2c06f91..d0b748c 100755
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -2461,9 +2461,14 @@
def is_tarfile(name):
"""Return True if name points to a tar archive that we
are able to handle, else return False.
+
+ 'name' should be a string, file, or file-like object.
"""
try:
- t = open(name)
+ if hasattr(name, "read"):
+ t = open(fileobj=name)
+ else:
+ t = open(name)
t.close()
return True
except TarError:
diff --git a/Lib/test/test_tarfile.py b/Lib/test/test_tarfile.py
index 15324a4..6a90108 100644
--- a/Lib/test/test_tarfile.py
+++ b/Lib/test/test_tarfile.py
@@ -319,6 +319,38 @@
class CommonReadTest(ReadTest):
+ def test_is_tarfile_erroneous(self):
+ with open(tmpname, "wb"):
+ pass
+
+ # is_tarfile works on filenames
+ self.assertFalse(tarfile.is_tarfile(tmpname))
+
+ # is_tarfile works on path-like objects
+ self.assertFalse(tarfile.is_tarfile(pathlib.Path(tmpname)))
+
+ # is_tarfile works on file objects
+ with open(tmpname, "rb") as fobj:
+ self.assertFalse(tarfile.is_tarfile(fobj))
+
+ # is_tarfile works on file-like objects
+ self.assertFalse(tarfile.is_tarfile(io.BytesIO(b"invalid")))
+
+ def test_is_tarfile_valid(self):
+ # is_tarfile works on filenames
+ self.assertTrue(tarfile.is_tarfile(self.tarname))
+
+ # is_tarfile works on path-like objects
+ self.assertTrue(tarfile.is_tarfile(pathlib.Path(self.tarname)))
+
+ # is_tarfile works on file objects
+ with open(self.tarname, "rb") as fobj:
+ self.assertTrue(tarfile.is_tarfile(fobj))
+
+ # is_tarfile works on file-like objects
+ with open(self.tarname, "rb") as fobj:
+ self.assertTrue(tarfile.is_tarfile(io.BytesIO(fobj.read())))
+
def test_empty_tarfile(self):
# Test for issue6123: Allow opening empty archives.
# This test checks if tarfile.open() is able to open an empty tar