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