[Cython] __cinit__ swallowing exceptions

[Vitja Makarov]

2012/2/28 mark florisson <markflorisson88 at gmail.com>:
> On 28 February 2012 18:57, Vitja Makarov <vitja.makarov at gmail.com> wrote:
>> 2012/2/28 mark florisson <markflorisson88 at gmail.com>:
>>> On 28 February 2012 18:19, Lisandro Dalcin <dalcinl at gmail.com> wrote:
>>>> This is something I really have no idea about how to fix, so I'll ask
>>>> any of you to do it.
>>>>
>>>> How to reproduce. The quick example below should fail in the second to
>>>> last line in test_cinit.py, but it succeeds:
>>>>
>>>> $ cat cinit.pyx
>>>> cdef class A:
>>>>    def __cinit__(self, A a=None):
>>>>        pass
>>>>
>>>> $ cat test_cinit.py
>>>> import pyximport; pyximport.install()
>>>> from cinit import A
>>>> a = A(123)
>>>> print (a)
>>>>
>>>> $ python test_cinit.py
>>>> /home/dalcinl/.pyxbld/temp.linux-x86_64-2.7/pyrex/cinit.c:1429:13:
>>>> warning: ‘__pyx_clear_code_object_cache’ defined but not used
>>>> [-Wunused-function]
>>>> <cinit.A object at 0x7fd28f1b7920>
>>>>
>>>>
>>>> I think the issue is bad code generation. Please try to follow the
>>>> flow below, when ArgTypeTest fails, then "goto  __pyx_L1_error" but
>>>> __pyx_r is never initialized to -1, so the function (accidentally)
>>>> returns 0 indicating success. BTW, GCC warns about __pyx_r used before
>>>> initialization is some other code of mine (more complex, involving
>>>> inheritance, and the C compiler inlining code), but not for this
>>>> simple example.
>>>>
>>>>
>>>> static int __pyx_pw_5cinit_1A_1__cinit__(PyObject *__pyx_v_self,
>>>> PyObject *__pyx_args, PyObject *__pyx_kwds) {
>>>> ...
>>>>  int __pyx_r;
>>>> ...
>>>>  {
>>>>   ....  <arg unpacking code>....
>>>>  }
>>>>  goto __pyx_L4_argument_unpacking_done;
>>>> ...
>>>>  __pyx_L4_argument_unpacking_done:;
>>>>  if (unlikely(!__Pyx_ArgTypeTest(((PyObject *)__pyx_v_a),
>>>> __pyx_ptype_5cinit_A, 1, "a", 0))) {__pyx_filename = __pyx_f[0];
>>>> __pyx_lineno = 2; __pyx_clineno = __LINE__; goto __pyx_L1_error;}
>>>> ...
>>>>  __pyx_L1_error:;
>>>>  __pyx_L0:;
>>>>  __Pyx_RefNannyFinishContext();
>>>>  return __pyx_r;
>>>> }
>>>>
>>>>
>>>> BTW, valgrind is able to catch the issue:
>>>>
>>>>
>>>> $ touch cinit.pyx
>>>> $ CFLAGS=-O0 valgrind python test_cinit.py
>>>> ==6735== Memcheck, a memory error detector
>>>> ==6735== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al.
>>>> ==6735== Using Valgrind-3.6.1 and LibVEX; rerun with -h for copyright info
>>>> ==6735== Command: python test_cinit.py
>>>> ==6735==
>>>> /home/dalcinl/.pyxbld/temp.linux-x86_64-2.7/pyrex/cinit.c:1429:13:
>>>> warning: ‘__pyx_clear_code_object_cache’ defined but not used
>>>> [-Wunused-function]
>>>> ==6735== Conditional jump or move depends on uninitialised value(s)
>>>> ==6735==    at 0x12DA4635: __pyx_tp_new_5cinit_A (cinit.c:548)
>>>> ==6735==    by 0x3A87C9DCF2: ??? (in /usr/lib64/libpython2.7.so.1.0)
>>>> ==6735==    by 0x3A87C49192: PyObject_Call (in /usr/lib64/libpython2.7.so.1.0)
>>>> ==6735==    by 0x3A87CDE794: PyEval_EvalFrameEx (in
>>>> /usr/lib64/libpython2.7.so.1.0)
>>>> ==6735==    by 0x3A87CE15A4: PyEval_EvalCodeEx (in
>>>> /usr/lib64/libpython2.7.so.1.0)
>>>> ==6735==    by 0x3A87CE16D1: PyEval_EvalCode (in /usr/lib64/libpython2.7.so.1.0)
>>>> ==6735==    by 0x3A87CFB9EB: ??? (in /usr/lib64/libpython2.7.so.1.0)
>>>> ==6735==    by 0x3A87CFC7EF: PyRun_FileExFlags (in
>>>> /usr/lib64/libpython2.7.so.1.0)
>>>> ==6735==    by 0x3A87CFD26E: PyRun_SimpleFileExFlags (in
>>>> /usr/lib64/libpython2.7.so.1.0)
>>>> ==6735==    by 0x3A87D0E744: Py_Main (in /usr/lib64/libpython2.7.so.1.0)
>>>> ==6735==    by 0x56F969C: (below main) (in /lib64/libc-2.14.90.so)
>>>> ==6735==
>>>> <cinit.A object at 0xec47430>
>>>> ==6735==
>>>> ==6735== HEAP SUMMARY:
>>>> ==6735==     in use at exit: 8,870,441 bytes in 53,569 blocks
>>>> ==6735==   total heap usage: 391,334 allocs, 337,765 frees, 94,515,287
>>>> bytes allocated
>>>> ==6735==
>>>> ==6735== LEAK SUMMARY:
>>>> ==6735==    definitely lost: 0 bytes in 0 blocks
>>>> ==6735==    indirectly lost: 0 bytes in 0 blocks
>>>> ==6735==      possibly lost: 2,319,018 bytes in 15,424 blocks
>>>> ==6735==    still reachable: 6,551,423 bytes in 38,145 blocks
>>>> ==6735==         suppressed: 0 bytes in 0 blocks
>>>> ==6735== Rerun with --leak-check=full to see details of leaked memory
>>>> ==6735==
>>>> ==6735== For counts of detected and suppressed errors, rerun with: -v
>>>> ==6735== Use --track-origins=yes to see where uninitialised values come from
>>>> ==6735== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 2 from 2)
>>>>
>>>>
>>>>
>>>> --
>>>> Lisandro Dalcin
>>>> ---------------
>>>> CIMEC (INTEC/CONICET-UNL)
>>>> Predio CONICET-Santa Fe
>>>> Colectora RN 168 Km 472, Paraje El Pozo
>>>> 3000 Santa Fe, Argentina
>>>> Tel: +54-342-4511594 (ext 1011)
>>>> Tel/Fax: +54-342-4511169
>>>> _______________________________________________
>>>> cython-devel mailing list
>>>> cython-devel at python.org
>>>> http://mail.python.org/mailman/listinfo/cython-devel
>>>
>>> Thanks, I fixed it here: https://github.com/markflorisson88/cython
>>>
>>> It should probably have more tests, also for other special methods.
>>
>>
>> This bug was introduced by DefNode refactoring.
>>
>> Mark, your fix isn't correct __pyx_r should be set to error_value() on
>> error just like DefNode does.
>
> Right, that would be work for all cases. Could you fix it and push to master?
>

Sure.

-- 
vitja.