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miss-islingtonserhiy-storchakaclaude
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[3.13] gh-66172: Don't let a corrupt config file prevent IDLE from starting (GH-152764) (#157460)
gh-66172: Don't let a corrupt config file prevent IDLE from starting (GH-152764) If a user configuration file cannot be read, because of either bad unicode or configuration, rename it with a ".bad" suffix, use default settings, and warn the user with a message box. --------- (cherry picked from commit ae0d6cc) Co-authored-by: Serhiy Storchaka <storchaka@gmail.com> Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
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Lines changed: 77 additions & 3 deletions

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‎Lib/idlelib/config.py‎

Lines changed: 25 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -25,7 +25,7 @@
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"""
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# TODOs added Oct 2014, tjr
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28-
from configparser import ConfigParser
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from configparser import ConfigParser, Error as ConfigParserError
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import os
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import sys
3131

@@ -74,7 +74,7 @@ def GetOptionList(self, section):
7474
def Load(self):
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"Load the configuration file from disk."
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if self.file and os.path.exists(self.file):
77-
with open(self.file, encoding='utf-8', errors='replace') as f:
77+
with open(self.file, encoding='utf-8') as f:
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self.read_file(f)
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8080
class IdleUserConfParser(IdleConfParser):
@@ -159,6 +159,7 @@ def __init__(self, _utest=False):
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self.defaultCfg = {}
160160
self.userCfg = {}
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self.cfg = {} # TODO use to select userCfg vs defaultCfg
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self.file_load_errors = [] # (file, error) for unparsable cfg files.
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163164
# See https://bugs.python.org/issue4630#msg356516 for following.
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# self.blink_off_time = <first editor text>['insertofftime']
@@ -795,7 +796,28 @@ def LoadCfgFiles(self):
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"Load all configuration files."
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for key in self.defaultCfg:
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self.defaultCfg[key].Load()
798-
self.userCfg[key].Load() #same keys
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try:
800+
self.userCfg[key].Load() # same keys
801+
except (ConfigParserError, UnicodeDecodeError) as err:
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# Move an invalid user file aside instead of losing it
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# or failing to start (gh-66172).
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file = self.userCfg[key].file
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self.file_load_errors.append((file, err))
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try:
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os.replace(file, file + '.bad')
808+
except OSError:
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pass
810+
811+
def file_load_error_message(self):
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"Return a warning about invalid config files, or None."
813+
if not self.file_load_errors:
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return None
815+
files = '\n'.join(
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f' {file}:\n {type(err).__name__}: {str(err).splitlines()[0]}'
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for file, err in self.file_load_errors)
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return ('The following IDLE configuration files could not be read. '
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'They were renamed by appending ".bad", and default settings '
820+
'are used instead:\n\n' + files)
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800822
def SaveUserCfgFiles(self):
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"Write all loaded user configuration files to disk."

‎Lib/idlelib/idle_test/test_config.py‎

Lines changed: 43 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -312,6 +312,49 @@ def test_load_cfg_files(self):
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eq(conf.userCfg['foo'].Get('Foo Bar', 'foo'), 'newbar')
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eq(conf.userCfg['foo'].GetOptionList('Foo Bar'), ['foo'])
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315+
def test_load_cfg_files_bad_format(self):
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# gh-66172: rename an unparsable user file and save the exception.
317+
conf = self.new_config(_utest=True)
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tmpdir = tempfile.TemporaryDirectory()
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self.addCleanup(tmpdir.cleanup)
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confpath = os.path.join(tmpdir.name, 'config-extensions.cfg')
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with open(confpath, 'w') as f:
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f.write('enable=1\n') # No section header.
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conf.defaultCfg['foo'] = config.IdleConfParser('') # Empty, valid.
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conf.userCfg['foo'] = config.IdleUserConfParser(confpath)
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self.assertIsNone(conf.file_load_error_message())
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conf.LoadCfgFiles() # Must not raise.
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self.assertEqual(len(conf.file_load_errors), 1)
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file, err = conf.file_load_errors[0]
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self.assertEqual(file, confpath)
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# The bad file is moved aside, not left to be overwritten or deleted.
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self.assertFalse(os.path.exists(confpath))
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with open(confpath + '.bad') as f:
335+
self.assertEqual(f.read(), 'enable=1\n')
336+
message = conf.file_load_error_message()
337+
self.assertIn(confpath, message)
338+
self.assertIn('MissingSectionHeaderError', message)
339+
340+
def test_load_cfg_files_bad_encoding(self):
341+
# gh-66172: a file that is not valid UTF-8 is handled like a bad parse.
342+
conf = self.new_config(_utest=True)
343+
tmpdir = tempfile.TemporaryDirectory()
344+
self.addCleanup(tmpdir.cleanup)
345+
confpath = os.path.join(tmpdir.name, 'config-main.cfg')
346+
with open(confpath, 'wb') as f:
347+
f.write(b'[Section]\nkey = \xff\n') # Invalid UTF-8.
348+
conf.defaultCfg['foo'] = config.IdleConfParser('') # Empty, valid.
349+
conf.userCfg['foo'] = config.IdleUserConfParser(confpath)
350+
351+
conf.LoadCfgFiles() # Must not raise.
352+
353+
self.assertEqual(len(conf.file_load_errors), 1)
354+
self.assertIsInstance(conf.file_load_errors[0][1], UnicodeDecodeError)
355+
self.assertFalse(os.path.exists(confpath))
356+
self.assertTrue(os.path.exists(confpath + '.bad'))
357+
315358
def test_save_user_cfg_files(self):
316359
conf = self.mock_config()
317360

‎Lib/idlelib/pyshell.py‎

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1612,6 +1612,12 @@ def main():
16121612
root.withdraw()
16131613
fix_scaling(root)
16141614

1615+
# Warn about configuration files that could not be parsed (gh-66172).
1616+
config_error = idleConf.file_load_error_message()
1617+
if config_error:
1618+
messagebox.showwarning('IDLE Configuration Warning', config_error,
1619+
parent=root)
1620+
16151621
# set application icon
16161622
icondir = os.path.join(os.path.dirname(__file__), 'Icons')
16171623
if system() == 'Windows':

‎Misc/NEWS.d/next/IDLE/2026-07-01-13-30-00.gh-issue-66172.Qm4xR7.rst‎

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,3 @@
1+
IDLE no longer fails to start when a user configuration file is corrupt.
2+
The unparsable file is renamed with a ".bad" suffix, default settings are
3+
used instead, and a warning lists the affected files.

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