[Cython] __cinit__ swallowing exceptions

[Vitja Makarov]

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.

-- 
vitja.