C API PyObject_Call segfaults with string
Jen Kris
jenkris at tutanota.com
Thu Feb 10 15:00:51 EST 2022
With the help of PyErr_Print() I have it solved. Here is the final code (the part relevant to sents):
Py_ssize_t listIndex = 0;
pListItem = PyList_GetItem(pFileIds, listIndex);
pListStrE = PyUnicode_AsEncodedString(pListItem, "UTF-8", "strict");
pListStr = PyBytes_AS_STRING(pListStrE); // Borrowed pointer
// Then: sentences = gutenberg.sents(fileid) - this is a sequence item
PyObject *c_args = Py_BuildValue("s", pListStr);
PyObject *args_tuple = PyTuple_New(1);
PyTuple_SetItem(args_tuple, 0, c_args);
pSents = PyObject_CallObject(pSentMod, args_tuple);
if ( pSents == 0x0){
PyErr_Print();
return return_value; }
As you mentioned yesterday, CallObject needs a tuple, so that was the problem. Now it works.
You also asked why I don't just use pListStrE. I tried that and got a long error message from PyErr_Print. I'm not far enough along in my C_API work to understand why, but it doesn't work.
Thanks very much for your help on this.
Jen
Feb 9, 2022, 17:40 by songofacandy at gmail.com:
> On Thu, Feb 10, 2022 at 10:37 AM Jen Kris <jenkris at tutanota.com> wrote:
>
>>
>> I'm using Python 3.8 so I tried your second choice:
>>
>> pSents = PyObject_CallFunctionObjArgs(pSentMod, pListItem);
>>
>> but pSents is 0x0. pSentMod and pListItem are valid pointers.
>>
>
> It means exception happened.
> If you are writing Python/C function, return NULL (e.g. `if (pSents ==
> NULL) return NULL`)
> Then Python show the exception and traceback for you.
>
> --
> Inada Naoki <songofacandy at gmail.com>
>
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