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bpo-32749: Make dbm.dumb databases more cosistent with other dbm databases. (#5497)

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Serhiy Storchaka 2018-02-05 22:47:31 +02:00 committed by GitHub
parent c309bcfb9f
commit 6c85efa5a6
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5 changed files with 50 additions and 46 deletions
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27
Doc/library/dbm.rst
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@ -339,9 +339,23 @@ The module defines the following:
dumbdbm database is created, files with :file:`.dat` and :file:`.dir` extensions
are created.
The optional *flag* argument supports only the semantics of ``'c'``
and ``'n'`` values. Other values will default to database being always
opened for update, and will be created if it does not exist.
The optional *flag* argument can be:
+---------+-------------------------------------------+
| Value | Meaning |
+=========+===========================================+
| ``'r'`` | Open existing database for reading only |
| | (default) |
+---------+-------------------------------------------+
| ``'w'`` | Open existing database for reading and |
| | writing |
+---------+-------------------------------------------+
| ``'c'`` | Open database for reading and writing, |
| | creating it if it doesn't exist |
+---------+-------------------------------------------+
| ``'n'`` | Always create a new, empty database, open |
| | for reading and writing |
+---------+-------------------------------------------+
The optional *mode* argument is the Unix mode of the file, used only when the
database has to be created. It defaults to octal ``0o666`` (and will be modified
@ -351,9 +365,10 @@ The module defines the following:
:func:`.open` always creates a new database when the flag has the value
``'n'``.
.. deprecated-removed:: 3.6 3.8
Creating database in ``'r'`` and ``'w'`` modes. Modifying database in
``'r'`` mode.
.. versionchanged:: 3.8
A database opened with flags ``'r'`` is now read-only. Opening with
flags ``'r'`` and ``'w'`` no longer creates a database if it does not
exist.
In addition to the methods provided by the
:class:`collections.abc.MutableMapping` class, :class:`dumbdbm` objects

5
Doc/whatsnew/3.8.rst
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@ -130,3 +130,8 @@ Changes in the Python API
arguments for changing the selection was deprecated in Python 3.6. Use
specialized methods like :meth:`~tkinter.ttk.Treeview.selection_set` for
changing the selection. (Contributed by Serhiy Storchaka in :issue:`31508`.)
* A :mod:`dbm.dumb` database opened with flags ``'r'`` is now read-only.
:func:`dbm.dumb.open` with flags ``'r'`` and ``'w'`` no longer creates
a database if it does not exist.
(Contributed by Serhiy Storchaka in :issue:`32749`.)

26
Lib/dbm/dumb.py
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@ -82,10 +82,7 @@ class _Database(collections.abc.MutableMapping):
f = _io.open(self._datfile, 'r', encoding="Latin-1")
except OSError:
if flag not in ('c', 'n'):
import warnings
warnings.warn("The database file is missing, the "
"semantics of the 'c' flag will be used.",
DeprecationWarning, stacklevel=4)
raise
with _io.open(self._datfile, 'w', encoding="Latin-1") as f:
self._chmod(self._datfile)
else:
@ -93,18 +90,15 @@ class _Database(collections.abc.MutableMapping):
# Read directory file into the in-memory index dict.
def _update(self, flag):
self._modified = False
self._index = {}
try:
f = _io.open(self._dirfile, 'r', encoding="Latin-1")
except OSError:
self._modified = not self._readonly
if flag not in ('c', 'n'):
import warnings
warnings.warn("The index file is missing, the "
"semantics of the 'c' flag will be used.",
DeprecationWarning, stacklevel=4)
raise
self._modified = True
else:
self._modified = False
with f:
for line in f:
line = line.rstrip()
@ -191,9 +185,7 @@ class _Database(collections.abc.MutableMapping):
def __setitem__(self, key, val):
if self._readonly:
import warnings
warnings.warn('The database is opened for reading only',
DeprecationWarning, stacklevel=2)
raise ValueError('The database is opened for reading only')
if isinstance(key, str):
key = key.encode('utf-8')
elif not isinstance(key, (bytes, bytearray)):
@ -230,9 +222,7 @@ class _Database(collections.abc.MutableMapping):
def __delitem__(self, key):
if self._readonly:
import warnings
warnings.warn('The database is opened for reading only',
DeprecationWarning, stacklevel=2)
raise ValueError('The database is opened for reading only')
if isinstance(key, str):
key = key.encode('utf-8')
self._verify_open()
@ -323,7 +313,5 @@ def open(file, flag='c', mode=0o666):
# Turn off any bits that are set in the umask
mode = mode & (~um)
if flag not in ('r', 'w', 'c', 'n'):
import warnings
warnings.warn("Flag must be one of 'r', 'w', 'c', or 'n'",
DeprecationWarning, stacklevel=2)
raise ValueError("Flag must be one of 'r', 'w', 'c', or 'n'")
return _Database(file, mode, flag=flag)

35
Lib/test/test_dbm_dumb.py
View File

@ -79,10 +79,10 @@ class DumbDBMTestCase(unittest.TestCase):
self.init_db()
f = dumbdbm.open(_fname, 'r')
self.read_helper(f)
with self.assertWarnsRegex(DeprecationWarning,
with self.assertRaisesRegex(ValueError,
'The database is opened for reading only'):
f[b'g'] = b'x'
with self.assertWarnsRegex(DeprecationWarning,
with self.assertRaisesRegex(ValueError,
'The database is opened for reading only'):
del f[b'a']
f.close()
@ -241,37 +241,30 @@ class DumbDBMTestCase(unittest.TestCase):
pass
self.assertEqual(stdout.getvalue(), '')
def test_warn_on_ignored_flags(self):
def test_missing_data(self):
for value in ('r', 'w'):
_delete_files()
with self.assertWarnsRegex(DeprecationWarning,
"The database file is missing, the "
"semantics of the 'c' flag will "
"be used."):
f = dumbdbm.open(_fname, value)
f.close()
with self.assertRaises(FileNotFoundError):
dumbdbm.open(_fname, value)
self.assertFalse(os.path.exists(_fname + '.dir'))
self.assertFalse(os.path.exists(_fname + '.bak'))
def test_missing_index(self):
with dumbdbm.open(_fname, 'n') as f:
pass
os.unlink(_fname + '.dir')
for value in ('r', 'w'):
with self.assertWarnsRegex(DeprecationWarning,
"The index file is missing, the "
"semantics of the 'c' flag will "
"be used."):
f = dumbdbm.open(_fname, value)
f.close()
self.assertEqual(os.path.exists(_fname + '.dir'), value == 'w')
with self.assertRaises(FileNotFoundError):
dumbdbm.open(_fname, value)
self.assertFalse(os.path.exists(_fname + '.dir'))
self.assertFalse(os.path.exists(_fname + '.bak'))
def test_invalid_flag(self):
for flag in ('x', 'rf', None):
with self.assertWarnsRegex(DeprecationWarning,
"Flag must be one of "
"'r', 'w', 'c', or 'n'"):
f = dumbdbm.open(_fname, flag)
f.close()
with self.assertRaisesRegex(ValueError,
"Flag must be one of "
"'r', 'w', 'c', or 'n'"):
dumbdbm.open(_fname, flag)
@unittest.skipUnless(hasattr(os, 'chmod'), 'test needs os.chmod()')
def test_readonly_files(self):

3
Misc/NEWS.d/next/Library/2018-02-02-17-21-24.bpo-32749.u5scIn.rst Normal file
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@ -0,0 +1,3 @@
A :mod:`dbm.dumb` database opened with flags 'r' is now read-only.
:func:`dbm.dumb.open` with flags 'r' and 'w' no longer creates a database if
it does not exist.