Embedded python crashed on 4th run, if "ctypes" is used

[warlock]

BPO	6869
Nosy	@theller
Files	fix_ctypes_crash.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/theller'
closed_at = <Date 2010-08-08.18:29:31.227>
created_at = <Date 2009-09-09.08:31:13.900>
labels = ['ctypes', 'type-crash']
title = 'Embedded python crashed on 4th run, if "ctypes" is used'
updated_at = <Date 2010-09-12.16:20:38.048>
user = 'https://bugs.python.org/warlock'

bugs.python.org fields:

activity = <Date 2010-09-12.16:20:38.048>
actor = 'ocean-city'
assignee = 'theller'
closed = True
closed_date = <Date 2010-08-08.18:29:31.227>
closer = 'theller'
components = ['ctypes']
creation = <Date 2009-09-09.08:31:13.900>
creator = 'warlock'
dependencies = []
files = ['14936']
hgrepos = []
issue_num = 6869
keywords = ['patch']
message_count = 7.0
messages = ['92444', '92449', '92555', '92880', '102369', '113297', '116211']
nosy_count = 7.0
nosy_names = ['theller', 'ocean-city', 'warlock', 'mkp', 'robince', 'nik.lutz@gmail.com', 'tanaga']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'patch review'
status = 'closed'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue6869'
versions = ['Python 3.1', 'Python 2.7', 'Python 3.2']

[warlock]

When embedding python from C, and importing "ctypes" module in embedded
script, it always crashes on Py_Finalize() on 4th cycle.
Tested with both PyRun_SimpleString(...) and PyRun_String(...).
Platform: Windows XP
IDE's: LabWindows/CVI 8.5 and Code::Blocks/gcc

Code:
--------------------------

#include <stdio.h>
#include <python.h>

int main()
{
    int i;
    for (i=0; i<10; i++)
    {
        printf("--- %d ---\n", i);
        Py_Initialize();
        PyRun_SimpleString("import ctypes");
        Py_Finalize();
    }
    return 0;
}

---

Output:
--------------------------------
--- 0 ---
--- 1 ---
--- 2 ---
--- 3 ---

Process returned -1073741819 (0xC0000005) execution time : 3.109 s
Press any key to continue.
--------------------------------

[warlock]

Tested
   obj=PyImport_ImportModule("ctypes");
   Py_DECREF(obj);
instead of PyRun_SimpleString(...) - same result

[mkp]

on python2.5 / mac os x 10.5.7:

$ cat main.c
#include <stdio.h>
#include <python.h>

int main()
{
    int i;
    for (i=0; i<10; i++)
    {
        printf("--- %d ---\n", i);
        Py_Initialize();
        PyRun_SimpleString("import ctypes");
        Py_Finalize();
    }
    return 0;
}

$ gcc -I/usr/include/python2.5/ -L/usr/lib/python2.5/ -lpython main.c
$ ./a.out 
--- 0 

---

--- 1 ---
--- 2 ---
--- 3 ---
Assertion failed: (type->tp_flags & Py_TPFLAGS_HEAPTYPE), function
type_dealloc, file Objects/typeobject.c, line 2148.
Abort trap
$ uname -mprsv
Darwin 9.7.0 Darwin Kernel Version 9.7.0: Tue Mar 31 22:52:17 PDT 2009;
root:xnu-1228.12.14~1/RELEASE_I386 i386 i386

[ocean-city]

I hope attached patch will fix this issue.

[niklutzgmailcom]

I can confirm that the patch fix this issue. I adapted the patch (variable names changed):

5523a5524

    Py_INCREF(&Struct_Type);

5529a5531

    Py_INCREF(&Union_Type);

5535a5538

    Py_INCREF(&Pointer_Type);

5541a5545

    Py_INCREF(&Array_Type);

5547a5552

    Py_INCREF(&Simple_Type);

5553a5559

    Py_INCREF(&CFuncPtr_Type); 

Platform: Linux (kubuntu 9.10 x64)
Python: 2.6.4-0ubuntu3

[theller]

Fixed in rev 83841 (py3k), rev 83842 (release31-maint), and rev 83843 (release27-maint).

Thanks for the patch.

[ocean-city]

I found another refcount bug in Python3.x.
Fixed in r84741(py3k), r84742(release31-maint).