8000 gh-65052: Prevent pdb from crashing when trying to display objects by gaogaotiantian · Pull Request #110578 · python/cpython · GitHub
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gh-65052: Prevent pdb from crashing when trying to display objects #110578

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Merged
merged 3 commits into from
Oct 11, 2023
Merged

gh-65052: Prevent pdb from crashing when trying to display objects #110578

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ce54e8d
Prevent pdb from crashing when trying to display objects
gaogaotiantian Oct 9, 2023
c59459e
📜🤖 Added by blurb_it.
blurb-it[bot] Oct 9, 2023
605d43c
Improve error message for _safe_repr
gaogaotiantian Oct 11, 2023
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21 changes: 14 additions & 7 deletions Lib/pdb.py
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Original file line number Diff line number Diff line change
Expand Up @@ -431,8 +431,9 @@ def preloop(self):
# fields are changed to be displayed
if newvalue is not oldvalue and newvalue != oldvalue:
displaying[expr] = newvalue
self.message('display %s: %r [old: %r]' %
(expr, newvalue, oldvalue))
self.message('display %s: %s [old: %s]' %
(expr, self._safe_repr(newvalue, expr),
self._safe_repr(oldvalue, expr)))

def _get_tb_and_exceptions(self, tb_or_exc):
"""
Expand Down Expand Up @@ -1460,7 +1461,7 @@ def do_args(self, arg):
for i in range(n):
name = co.co_varnames[i]
if name in dict:
self.message('%s = %r' % (name, dict[name]))
self.message('%s = %s' % (name, self._safe_repr(dict[name], name)))
else:
self.message('%s = *** undefined ***' % (name,))
do_a = do_args
Expand All @@ -1474,7 +1475,7 @@ def do_retval(self, arg):
self._print_invalid_arg(arg)
return
if '__return__' in self.curframe_locals:
self.message(repr(self.curframe_locals['__return__']))
self.message(self._safe_repr(self.curframe_locals['__return__'], "retval"))
else:
self.error('Not yet returned!')
do_rv = do_retval
Expand Down Expand Up @@ -1509,6 +1510,12 @@ def _msg_val_func(self, arg, func):
except:
self._error_exc()

def _safe_repr(self, obj, expr):
try:
return repr(obj)
except Exception as e:
return _rstr(f"*** repr({expr}) failed: {self._format_exc(e)} ***")
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Do we use f-strings or % in this script? Or a mixture of the two?

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I'm using f-strings for all new code. There are plenty of usages with % as pdb is old. Do you think it would be helpful to have a PR to update all strings to f-strings? It would eliminate the mixture.

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Probably not worth the risk of breaking something.


def do_p(self, arg):
"""p expression

Expand Down Expand Up @@ -1688,8 +1695,8 @@ def do_display(self, arg):
if not arg:
if self.displaying:
self.message('Currently displaying:')
for item in self.displaying.get(self.curframe, {}).items():
self.message('%s: %r' % item)
for key, val in self.displaying.get(self.curframe, {}).items():
self.message('%s: %s' % (key, self._safe_repr(val, key)))
else:
self.message('No expression is being displayed')
else:
Expand All @@ -1698,7 +1705,7 @@ def do_display(self, arg):
else:
val = self._getval_except(arg)
self.displaying.setdefault(self.curframe, {})[arg] = val
self.message('display %s: %r' % (arg, val))
self.message('display %s: %s' % (arg, self._safe_repr(val, arg)))

complete_display = _complete_expression

Expand Down
47 changes: 47 additions & 0 deletions Lib/test/test_pdb.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2350,6 +2350,53 @@ def test_pdb_ambiguous_statements():
(Pdb) continue
"""

def test_pdb_issue_gh_65052():
"""See GH-65052

args, retval and display should not crash if the object is not displayable
>>> class A:
... def __new__(cls):
... import pdb; pdb.Pdb(nosigint=True, readrc=False).set_trace()
... return object.__new__(cls)
... def __init__(self):
... import pdb; pdb.Pdb(nosigint=True, readrc=False).set_trace()
... self.a = 1
... def __repr__(self):
... return self.a

>>> def test_function():
... A()
>>> with PdbTestInput([ # doctest: +ELLIPSIS +NORMALIZE_WHITESPACE
... 's',
... 'retval',
... 'continue',
... 'args',
... 'display self',
... 'display',
... 'continue',
... ]):
... test_function()
> <doctest test.test_pdb.test_pdb_issue_gh_65052[0]>(4)__new__()
-> return object.__new__(cls)
(Pdb) s
--Return--
> <doctest test.test_pdb.test_pdb_issue_gh_65052[0]>(4)__new__()-><A instance at ...>
-> return object.__new__(cls)
(Pdb) retval
*** repr(retval) failed: AttributeError: 'A' object has no attribute 'a' ***
(Pdb) continue
> <doctest test.test_pdb.test_pdb_issue_gh_65052[0]>(7)__init__()
-> self.a = 1
(Pdb) args
self = *** repr(self) failed: AttributeError: 'A' object has no attribute 'a' ***
(Pdb) display self
display self: *** repr(self) failed: AttributeError: 'A' object has no attribute 'a' ***
(Pdb) display
Currently displaying:
self: *** repr(self) failed: AttributeError: 'A' object has no attribute 'a' ***
(Pdb) continue
"""


@support.requires_subprocess()
class PdbTestCase(unittest.TestCase):
Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2023-10-09-19-09-32.gh-issue-65052.C2mRlo.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Prevent :mod:`pdb` from crashing when trying to display undisplayable objects
0