Re: Segmentation fault in Python 3 - Cursor - chained exceptions

Thank you for the quick response. Do you already have any plans, when will
new version be released ?


2014-05-13 23:17 GMT+02:00 Anthony Tuininga <[email protected]>:

> Thanks for the simple program to demonstrate the problem. :-) I have just
> pushed a change to the source that resolves this issue. Apparently in
> Python 3 the first time the exception is referenced it is not normalized
> and so the error object I am creating is immediately accessible. The second
> level of exception results in a normalized exception which means that it
> can't be accessed in the same way. Fortunately the normalization can be
> forced so that I can access the error object the same way each time. A
> subtle and rare bug so I appreciate the pointer!
>
> Anthony
>
>
> On Tue, May 13, 2014 at 1:15 AM, Boris Dzuba <[email protected]>wrote:
>
>> Hi all,
>>
>> The following test program gives a segmentation fault:
>>
>> C:\>python
>> Python 3.3.3 (v3.3.3:c3896275c0f6, Nov 18 2013, 21:19:30) [MSC v.1600 64
>> bit (AMD64)] on win32
>> Type "help", "copyright", "credits" or "license" for more information.
>> >>> import cx_Oracle
>> >>> c=cx_Oracle.connect(<connect string>).cursor()
>> >>> try:
>> ...     c.execute("select")
>> ... except:
>> ...     try:
>> ...             c.execute("select")
>> ...     except:
>> ...             pass
>> ...
>>
>> C:\>
>>
>> Access Violation
>> Faulting application name: python.exe
>> Fault offset: 0x000000000000cacd
>>
>>
>> Platform: 64bit, Win7, Oracle Client 11g (11.2.0.1.0), python 3.3.3,
>> cx_Oracle 5.1.2
>>
>>
>>
>> At a guess, the problem is because in the function
>> Cursor_SetErrorOffset() /Cursor.c/:
>>
>> static void Cursor_SetErrorOffset(
>>     udt_Cursor *self)                   // cursor to get the error offset
>> from
>> {
>>     PyObject *type, *value, *traceback;
>>     udt_Error *error;
>>
>>     PyErr_Fetch(&type, &value, &traceback);
>>     if (type == g_DatabaseErrorException) {
>>         error = (udt_Error*) value;
>>         OCIAttrGet(self->handle, OCI_HTYPE_STMT, &error->offset, 0,
>>                 OCI_ATTR_PARSE_ERROR_OFFSET,
>> self->environment->errorHandle);
>>     }
>>     PyErr_Restore(type, value, traceback);
>> }
>>
>> OCIAttrGet() call attempts to write a value to the address
>> /&error->offset/,
>> therefore after the end of an allocated memory block of the borrowed
>> pointer /PyObject *value/
>>
>> typedef struct {
>>     PyObject_HEAD
>>     sb4 code;
>>     ub4 offset;
>>     PyObject *message;
>>     const char *context;
>> } udt_Error;
>>
>>
>> Commenting it out /* OCIAttrGet(self->handle, OCI_HTYPE_STMT,
>> &error->offset, 0, OCI_ATTR_PARSE_ERROR_OFFSET,
>> self->environment->errorHandle);*/
>> fix this crash!
>>
>>
>> Regards,
>> Boris
>>
>>
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>>
>
>
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