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ctypes segfaults when passing a unicode string to a function without argtypes #49453

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amauryfa opened this issue Feb 10, 2009 · 2 comments
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ctypes segfaults when passing a unicode string to a function without argtypes #49453

amauryfa opened this issue Feb 10, 2009 · 2 comments
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@theller
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topic-ctypes type-crash A hard crash of the interpreter, possibly with a core dump

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@amauryfa
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BPO 5203
Nosy @theller, @amauryfa

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 2009-02-10.19:07:27.013>
created_at = <Date 2009-02-10.12:48:03.105>
labels = ['ctypes', 'type-crash']
title = 'ctypes segfaults when passing a unicode string to a function without argtypes'
updated_at = <Date 2009-02-10.19:07:27.011>
user = 'https://github.com/amauryfa'

bugs.python.org fields:

activity = <Date 2009-02-10.19:07:27.011>
actor = 'theller'
assignee = 'theller'
closed = True
closed_date = <Date 2009-02-10.19:07:27.013>
closer = 'theller'
components = ['ctypes']
creation = <Date 2009-02-10.12:48:03.105>
creator = 'amaury.forgeotdarc'
dependencies = []
files = []
hgrepos = []
issue_num = 5203
keywords = []
message_count = 2.0
messages = ['81544', '81582']
nosy_count = 2.0
nosy_names = ['theller', 'amaury.forgeotdarc']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue5203'
versions = ['Python 2.6', 'Python 2.7']
@amauryfa
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The following code segfaults on platforms where HAVE_USABLE_WCHAR_T is
not defined (for example: narrow unicode build and sizeof(wchar_t)==4)

>> from ctypes import *
>> import ctypes.util
>> CDLL(ctypes.util.find_library('c')).wcslen(u'text')

(it works if the argtypes member is defined)

The reason is a non initialized structure, and the correction is trivial:

--- Modules/_ctypes/callproc.c~ 2007-06-15 19:10:41.000000000 +0200
+++ Modules/_ctypes/callproc.c  2009-02-10 13:28:10.000000000 +0100
@@ -538,6 +538,7 @@
                int size = PyUnicode_GET_SIZE(obj);
                size += 1; /* terminating NUL */
                size *= sizeof(wchar_t);
+               pa->ffi_type = &ffi_type_pointer;
                pa->value.p = PyMem_Malloc(size);
                if (!pa->value.p) {
                        PyErr_NoMemory();

@amauryfa amauryfa added topic-ctypes type-crash A hard crash of the interpreter, possibly with a core dump labels Feb 10, 2009
@theller
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theller commented Feb 10, 2009

Fixed in trunk (rev 69505) and release26-maint (rev 69506).
The bug was already fixed in a different way in py3k and release30-maint
although in a different way, I merged this exact fix anyway (rev 69507
and rev 69508).

Thanks.

@theller theller closed this as completed Feb 10, 2009
@ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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