Question

我正在为python程序开发我的第一个C ++扩展。我一直试图调试这段特殊的代码几个小时，而且我的想法不合时宜。

段错误似乎与传递给C ++代码的PyArrayObject old_simplices_array有关。该对象是2d numpy array类型的uint32。

此代码直接从scipy.weave放在一起修改。当代码被scipy.weave.inline格式化并使用时，一切正常。这似乎消除了我的程序的python部分和算法本身可能成为罪魁祸首。

只留下语法和类型。有没有人看到任何不正确的语法或类型转换代码？

static PyObject* exterior(PyObject* self,
                          PyArrayObject* old_simplices_array)
{
    const short unsigned int step = old_simplices_array->dimensions[1];
    const short unsigned int j_max = step - 1;
    const long unsigned int col_max = 
        old_simplices_array->dimensions[0] * step;
    short unsigned int j, k, face_index;
    long unsigned int col;
    unsigned int num_simplices = 0;

    PyObject* indices = PyList_New(0);
    PyObject* indptr =  PyList_New(0);
    PyObject* data =  PyList_New(0);
    PyObject* simplices = PyList_New(0);
    PyList_Append(indptr, PyLong_FromLong(0));
    PyObject* simplex_to_index = PyDict_New();

    for(col = 0; col < col_max; col+=step)
    {
        for(j = 0; j <= j_max; j++)
        {
            face_index = 0;
            PyObject* face = PyTuple_New(j_max);
            for(k = 0; k <= j_max; k++)
            {
                if(j != k)
                {
                    PyTuple_SetItem(face, face_index, 
                        PyLong_FromLong(old_simplices_array->data[col + k]));
                    face_index++;
                }
            }

            if(PyDict_Contains(simplex_to_index, face))
            {
                PyList_Append(indices, 
                    PyDict_GetItem(simplex_to_index, face));
            }
            else
            {
                PyDict_SetItem(simplex_to_index, face, 
                    PyLong_FromLong(num_simplices));
                PyList_Append(simplices, face);
                num_simplices++;
            }
            PyList_Append(data, PyLong_FromLong(1 - 2 * (j % 2)));
        }
        PyList_Append(indptr, PyLong_FromLong(col + j));
    }
    return PyTuple_Pack(3, PyTuple_Pack(3, data, indices, indptr), simplices,
        simplex_to_index);
}

------ ------ UPDATE

gdb表示

const short unsigned int step = old_simplices_array->dimensions[1];

导致段错误。我滥用了类型吗？

------ ------ UPDATE

尽管GDB告诉我，

const short unsigned int step = old_simplices_array->dimensions[1];

导致段错误，如果我在for循环之前从程序返回，我没有得到段错误（只是python方面的错误抱怨返回NoneType）。

这是完整的回溯：

Program received signal SIGSEGV, Segmentation fault.
exterior (self=<optimized out>, old_simplices_array=0xec0a50)
    at src/_alto.cpp:39
warning: Source file is more recent than executable.
39      const short unsigned int step = old_simplices_array->dimensions[1];
(gdb) bt
exterior (self=<optimized out>, old_simplices_array=0xec0a50)
    at src/_alto.cpp:39
0x00007ffff7aedad2 in PyEval_EvalFrameEx ()
   from /usr/lib/sagemath/local/lib/libpython2.7.so.1.0
0x00007ffff7aeddc9 in PyEval_EvalFrameEx ()
   from /usr/lib/sagemath/local/lib/libpython2.7.so.1.0
0x00007ffff7aee902 in PyEval_EvalCodeEx ()
   from /usr/lib/sagemath/local/lib/libpython2.7.so.1.0
0x00007ffff7a70ad6 in ?? ()
   from /usr/lib/sagemath/local/lib/libpython2.7.so.1.0
0x00007ffff7a4565e in PyObject_Call ()
   from /usr/lib/sagemath/local/lib/libpython2.7.so.1.0
0x00007ffff7a53b80 in ?? ()
   from /usr/lib/sagemath/local/lib/libpython2.7.so.1.0
0x00007ffff7a4565e in PyObject_Call ()
   from /usr/lib/sagemath/local/lib/libpython2.7.so.1.0
0x00007ffff7aaaea0 in ?? ()
   from /usr/lib/sagemath/local/lib/libpython2.7.so.1.0
0x00007ffff7aa68bc in ?? ()
   from /usr/lib/sagemath/local/lib/libpython2.7.so.1.0
0x00007ffff7a4565e in PyObject_Call ()
   from /usr/lib/sagemath/local/lib/libpython2.7.so.1.0
0x00007ffff7ae9bce in PyEval_EvalFrameEx ()
   from /usr/lib/sagemath/local/lib/libpython2.7.so.1.0
0x00007ffff7aee902 in PyEval_EvalCodeEx ()
   from /usr/lib/sagemath/local/lib/libpython2.7.so.1.0
0x00007ffff7aeea32 in PyEval_EvalCode ()
   from /usr/lib/sagemath/local/lib/libpython2.7.so.1.0
0x00007ffff7b103fa in PyRun_FileExFlags ()
   from /usr/lib/sagemath/local/lib/libpython2.7.so.1.0
0x00007ffff7b10e3d in PyRun_SimpleFileExFlags ()
   from /usr/lib/sagemath/local/lib/libpython2.7.so.1.0
0x00007ffff7b26972 in Py_Main ()
   from /usr/lib/sagemath/local/lib/libpython2.7.so.1.0
0x00007ffff6d29ea5 in __libc_start_main ()
   from /lib/x86_64-linux-gnu/libc.so.6
0x00000000004006d1 in _start ()

Answer 1

通常，C模块中方法的签名是PyObject* f(PyObject* self, PyObject* args)，其中args旨在由PyArg_ParseTuple解析。您可以在代码scipy.weave生成：http://docs.scipy.org/doc/scipy/reference/tutorial/weave.html#a-quick-look-at-the-code）中看到这一点。除非有一些包装函数，否则您没有为您发布PyArg_ParseTuple调用，因此您的exterior方法必须调用它才能从通用PyArrayObject中提取PyObject* args。

Numpy C ++程序总是给出段错（很可能是滥用语法或类型）

1 个答案: