[Python-checkins] cpython (3.3): Issue #18879: When a method is looked up on a temporary file, avoid closing the
antoine.pitrou
python-checkins at python.org
Sat Dec 21 22:19:21 CET 2013
http://hg.python.org/cpython/rev/f3b7a76fb778
changeset: 88113:f3b7a76fb778
branch: 3.3
parent: 88087:49dd8e1ef4c3
user: Antoine Pitrou <solipsis at pitrou.net>
date: Sat Dec 21 22:14:56 2013 +0100
summary:
Issue #18879: When a method is looked up on a temporary file, avoid closing the file before the method is possibly called.
files:
Lib/tempfile.py | 102 +++++++++++++++++--------
Lib/test/test_tempfile.py | 17 ++++
Misc/NEWS | 3 +
3 files changed, 87 insertions(+), 35 deletions(-)
diff --git a/Lib/tempfile.py b/Lib/tempfile.py
--- a/Lib/tempfile.py
+++ b/Lib/tempfile.py
@@ -27,6 +27,7 @@
# Imports.
+import functools as _functools
import warnings as _warnings
import sys as _sys
import io as _io
@@ -349,13 +350,10 @@
"No usable temporary filename found")
-class _TemporaryFileWrapper:
- """Temporary file wrapper
-
- This class provides a wrapper around files opened for
- temporary use. In particular, it seeks to automatically
- remove the file when it is no longer needed.
- """
+class _TemporaryFileCloser:
+ """A separate object allowing proper closing of a temporary file's
+ underlying file object, without adding a __del__ method to the
+ temporary file."""
def __init__(self, file, name, delete=True):
self.file = file
@@ -363,26 +361,6 @@
self.close_called = False
self.delete = delete
- def __getattr__(self, name):
- # Attribute lookups are delegated to the underlying file
- # and cached for non-numeric results
- # (i.e. methods are cached, closed and friends are not)
- file = self.__dict__['file']
- a = getattr(file, name)
- if not isinstance(a, int):
- setattr(self, name, a)
- return a
-
- # The underlying __enter__ method returns the wrong object
- # (self.file) so override it to return the wrapper
- def __enter__(self):
- self.file.__enter__()
- return self
-
- # iter() doesn't use __getattr__ to find the __iter__ method
- def __iter__(self):
- return iter(self.file)
-
# NT provides delete-on-close as a primitive, so we don't need
# the wrapper to do anything special. We still use it so that
# file.name is useful (i.e. not "(fdopen)") with NamedTemporaryFile.
@@ -401,18 +379,72 @@
if self.delete:
self.unlink(self.name)
+ # Need to ensure the file is deleted on __del__
def __del__(self):
self.close()
- # Need to trap __exit__ as well to ensure the file gets
- # deleted when used in a with statement
- def __exit__(self, exc, value, tb):
- result = self.file.__exit__(exc, value, tb)
- self.close()
- return result
else:
- def __exit__(self, exc, value, tb):
- self.file.__exit__(exc, value, tb)
+ def close(self):
+ if not self.close_called:
+ self.close_called = True
+ self.file.close()
+
+
+class _TemporaryFileWrapper:
+ """Temporary file wrapper
+
+ This class provides a wrapper around files opened for
+ temporary use. In particular, it seeks to automatically
+ remove the file when it is no longer needed.
+ """
+
+ def __init__(self, file, name, delete=True):
+ self.file = file
+ self.name = name
+ self.delete = delete
+ self._closer = _TemporaryFileCloser(file, name, delete)
+
+ def __getattr__(self, name):
+ # Attribute lookups are delegated to the underlying file
+ # and cached for non-numeric results
+ # (i.e. methods are cached, closed and friends are not)
+ file = self.__dict__['file']
+ a = getattr(file, name)
+ if hasattr(a, '__call__'):
+ func = a
+ @_functools.wraps(func)
+ def func_wrapper(*args, **kwargs):
+ return func(*args, **kwargs)
+ # Avoid closing the file as long as the wrapper is alive,
+ # see issue #18879.
+ func_wrapper._closer = self._closer
+ a = func_wrapper
+ if not isinstance(a, int):
+ setattr(self, name, a)
+ return a
+
+ # The underlying __enter__ method returns the wrong object
+ # (self.file) so override it to return the wrapper
+ def __enter__(self):
+ self.file.__enter__()
+ return self
+
+ # Need to trap __exit__ as well to ensure the file gets
+ # deleted when used in a with statement
+ def __exit__(self, exc, value, tb):
+ result = self.file.__exit__(exc, value, tb)
+ self.close()
+ return result
+
+ def close(self):
+ """
+ Close the temporary file, possibly deleting it.
+ """
+ self._closer.close()
+
+ # iter() doesn't use __getattr__ to find the __iter__ method
+ def __iter__(self):
+ return iter(self.file)
def NamedTemporaryFile(mode='w+b', buffering=-1, encoding=None,
diff --git a/Lib/test/test_tempfile.py b/Lib/test/test_tempfile.py
--- a/Lib/test/test_tempfile.py
+++ b/Lib/test/test_tempfile.py
@@ -8,6 +8,7 @@
import re
import warnings
import contextlib
+import weakref
import unittest
from test import support
@@ -674,6 +675,22 @@
self.do_create(pre="a", suf="b")
self.do_create(pre="aa", suf=".txt")
+ def test_method_lookup(self):
+ # Issue #18879: Looking up a temporary file method should keep it
+ # alive long enough.
+ f = self.do_create()
+ wr = weakref.ref(f)
+ write = f.write
+ write2 = f.write
+ del f
+ write(b'foo')
+ del write
+ write2(b'bar')
+ del write2
+ if support.check_impl_detail(cpython=True):
+ # No reference cycle was created.
+ self.assertIsNone(wr())
+
def test_creates_named(self):
# NamedTemporaryFile creates files with names
f = tempfile.NamedTemporaryFile()
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -29,6 +29,9 @@
Library
-------
+- Issue #18879: When a method is looked up on a temporary file, avoid closing
+ the file before the method is possibly called.
+
- Issue #20034: Updated alias mapping to most recent locale.alias file
from X.org distribution using makelocalealias.py.
--
Repository URL: http://hg.python.org/cpython
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