Issue #7232: Add support for the context manager protocol
to the TarFile class.
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@ -234,6 +234,14 @@ a header block followed by data blocks. It is possible to store a file in a tar
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archive several times. Each archive member is represented by a :class:`TarInfo`
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object, see :ref:`tarinfo-objects` for details.
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A :class:`TarFile` object can be used as a context manager in a :keyword:`with`
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statement. It will automatically be closed when the block is completed. Please
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note that in the event of an exception an archive opened for writing will not
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be finalized, only the internally used file object will be closed. See the
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:ref:`tar-examples` section for a use case.
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.. versionadded:: 2.7
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Added support for the context manager protocol.
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.. class:: TarFile(name=None, mode='r', fileobj=None, format=DEFAULT_FORMAT, tarinfo=TarInfo, dereference=False, ignore_zeros=False, encoding=ENCODING, errors=None, pax_headers=None, debug=0, errorlevel=0)
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@ -650,6 +658,13 @@ How to create an uncompressed tar archive from a list of filenames::
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tar.add(name)
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tar.close()
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The same example using the :keyword:`with` statement::
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import tarfile
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with tarfile.open("sample.tar", "w") as tar:
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for name in ["foo", "bar", "quux"]:
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tar.add(name)
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How to read a gzip compressed tar archive and display some member information::
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import tarfile
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@ -2411,6 +2411,20 @@ class TarFile(object):
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"""
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if level <= self.debug:
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print >> sys.stderr, msg
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def __enter__(self):
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self._check()
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return self
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def __exit__(self, type, value, traceback):
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if type is None:
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self.close()
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else:
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# An exception occurred. We must not call close() because
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# it would try to write end-of-archive blocks and padding.
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if not self._extfileobj:
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self.fileobj.close()
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self.closed = True
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# class TarFile
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class TarIter:
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@ -1292,6 +1292,65 @@ class LimitsTest(unittest.TestCase):
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tarinfo.tobuf(tarfile.PAX_FORMAT)
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class ContextManagerTest(unittest.TestCase):
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def test_basic(self):
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with tarfile.open(tarname) as tar:
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self.assertFalse(tar.closed, "closed inside runtime context")
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self.assertTrue(tar.closed, "context manager failed")
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def test_closed(self):
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# The __enter__() method is supposed to raise IOError
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# if the TarFile object is already closed.
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tar = tarfile.open(tarname)
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tar.close()
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with self.assertRaises(IOError):
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with tar:
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pass
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def test_exception(self):
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# Test if the IOError exception is passed through properly.
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with self.assertRaises(Exception) as exc:
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with tarfile.open(tarname) as tar:
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raise IOError
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self.assertIsInstance(exc.exception, IOError,
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"wrong exception raised in context manager")
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self.assertTrue(tar.closed, "context manager failed")
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def test_no_eof(self):
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# __exit__() must not write end-of-archive blocks if an
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# exception was raised.
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try:
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with tarfile.open(tmpname, "w") as tar:
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raise Exception
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except:
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pass
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self.assertEqual(os.path.getsize(tmpname), 0,
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"context manager wrote an end-of-archive block")
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self.assertTrue(tar.closed, "context manager failed")
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def test_eof(self):
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# __exit__() must write end-of-archive blocks, i.e. call
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# TarFile.close() if there was no error.
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with tarfile.open(tmpname, "w"):
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pass
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self.assertNotEqual(os.path.getsize(tmpname), 0,
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"context manager wrote no end-of-archive block")
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def test_fileobj(self):
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# Test that __exit__() did not close the external file
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# object.
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fobj = open(tmpname, "wb")
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try:
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with tarfile.open(fileobj=fobj, mode="w") as tar:
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raise Exception
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except:
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pass
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self.assertFalse(fobj.closed, "external file object was closed")
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self.assertTrue(tar.closed, "context manager failed")
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fobj.close()
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class GzipMiscReadTest(MiscReadTest):
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tarname = gzipname
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mode = "r:gz"
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@ -1371,6 +1430,7 @@ def test_main():
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PaxUnicodeTest,
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AppendTest,
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LimitsTest,
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ContextManagerTest,
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]
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if hasattr(os, "link"):
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