Issue #16800: tempfile.gettempdir() no longer left temporary files when

the disk is full.  Original patch by Amir Szekely.

Lib/tempfile.py

@@ -29,6 +29,7 @@ __all__ = [
 
 # Imports.
 
+import io as _io
 import os as _os
 import errno as _errno
 from random import Random as _Random
@@ -193,14 +194,17 @@ def _get_default_tempdir():
             name = namer.next()
             filename = _os.path.join(dir, name)
             try:
-                fd = _os.open(filename, flags, 0600)
-                fp = _os.fdopen(fd, 'w')
-                fp.write('blat')
-                fp.close()
-                _os.unlink(filename)
-                del fp, fd
+                fd = _os.open(filename, flags, 0o600)
+                try:
+                    try:
+                        fp = _io.open(fd, 'wb', buffering=0, closefd=False)
+                        fp.write(b'blat')
+                    finally:
+                        _os.close(fd)
+                finally:
+                    _os.unlink(filename)
                 return dir
-            except (OSError, IOError), e:
+            except (OSError, IOError) as e:
                 if e[0] != _errno.EEXIST:
                     break # no point trying more names in this directory
                 pass

Lib/test/test_support.py

@@ -1298,6 +1298,33 @@ def reap_children():
             except:
                 break
 
+@contextlib.contextmanager
+def swap_attr(obj, attr, new_val):
+    """Temporary swap out an attribute with a new object.
+
+    Usage:
+        with swap_attr(obj, "attr", 5):
+            ...
+
+        This will set obj.attr to 5 for the duration of the with: block,
+        restoring the old value at the end of the block. If `attr` doesn't
+        exist on `obj`, it will be created and then deleted at the end of the
+        block.
+    """
+    if hasattr(obj, attr):
+        real_val = getattr(obj, attr)
+        setattr(obj, attr, new_val)
+        try:
+            yield
+        finally:
+            setattr(obj, attr, real_val)
+    else:
+        setattr(obj, attr, new_val)
+        try:
+            yield
+        finally:
+            delattr(obj, attr)
+
 def py3k_bytes(b):
     """Emulate the py3k bytes() constructor.
 

Lib/test/test_tempfile.py

 # tempfile.py unit tests.
 import tempfile
+import errno
+import io
 import os
 import signal
+import shutil
 import sys
 import re
 import warnings
 
 import unittest
-from test import test_support
+from test import test_support as support
 
 warnings.filterwarnings("ignore",
                         category=RuntimeWarning,
@@ -177,7 +180,7 @@ class test__candidate_tempdir_list(TC):
         # _candidate_tempdir_list contains the expected directories
 
         # Make sure the interesting environment variables are all set.
-        with test_support.EnvironmentVarGuard() as env:
+        with support.EnvironmentVarGuard() as env:
             for envname in 'TMPDIR', 'TEMP', 'TMP':
                 dirname = os.getenv(envname)
                 if not dirname:
@@ -202,8 +205,51 @@ class test__candidate_tempdir_list(TC):
 
 test_classes.append(test__candidate_tempdir_list)
 
+# We test _get_default_tempdir some more by testing gettempdir.
 
-# We test _get_default_tempdir by testing gettempdir.
+class TestGetDefaultTempdir(TC):
+    """Test _get_default_tempdir()."""
+
+    def test_no_files_left_behind(self):
+        # use a private empty directory
+        our_temp_directory = tempfile.mkdtemp()
+        try:
+            # force _get_default_tempdir() to consider our empty directory
+            def our_candidate_list():
+                return [our_temp_directory]
+
+            with support.swap_attr(tempfile, "_candidate_tempdir_list",
+                                   our_candidate_list):
+                # verify our directory is empty after _get_default_tempdir()
+                tempfile._get_default_tempdir()
+                self.assertEqual(os.listdir(our_temp_directory), [])
+
+                def raise_OSError(*args, **kwargs):
+                    raise OSError(-1)
+
+                with support.swap_attr(io, "open", raise_OSError):
+                    # test again with failing io.open()
+                    with self.assertRaises(IOError) as cm:
+                        tempfile._get_default_tempdir()
+                    self.assertEqual(cm.exception.errno, errno.ENOENT)
+                    self.assertEqual(os.listdir(our_temp_directory), [])
+
+                open = io.open
+                def bad_writer(*args, **kwargs):
+                    fp = open(*args, **kwargs)
+                    fp.write = raise_OSError
+                    return fp
+
+                with support.swap_attr(io, "open", bad_writer):
+                    # test again with failing write()
+                    with self.assertRaises(IOError) as cm:
+                        tempfile._get_default_tempdir()
+                    self.assertEqual(cm.exception.errno, errno.ENOENT)
+                    self.assertEqual(os.listdir(our_temp_directory), [])
+        finally:
+            shutil.rmtree(our_temp_directory)
+
+test_classes.append(TestGetDefaultTempdir)
 
 
 class test__get_candidate_names(TC):
@@ -299,7 +345,7 @@ class test__mkstemp_inner(TC):
         if not has_spawnl:
             return            # ugh, can't use SkipTest.
 
-        if test_support.verbose:
+        if support.verbose:
             v="v"
         else:
             v="q"
@@ -913,7 +959,7 @@ if tempfile.NamedTemporaryFile is not tempfile.TemporaryFile:
     test_classes.append(test_TemporaryFile)
 
 def test_main():
-    test_support.run_unittest(*test_classes)
+    support.run_unittest(*test_classes)
 
 if __name__ == "__main__":
     test_main()

Misc/ACKS

@@ -974,6 +974,7 @@ Kalle Svensson
 Paul Swartz
 Thenault Sylvain
 Péter Szabó
+Amir Szekely
 Arfrever Frehtes Taifersar Arahesis
 Geoff Talvola
 William Tanksley

Misc/NEWS

@@ -202,6 +202,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #16800: tempfile.gettempdir() no longer left temporary files when
+  the disk is full.  Original patch by Amir Szekely.
+
 - Issue #13555: cPickle now supports files larger than 2 GiB.
 
 - Issue #17052: unittest discovery should use self.testLoader.