[New-bugs-announce] [issue16906] Bug in _PyUnicode_ClearStaticStrings() method of unicodeobject.c

[Prashant Kurnawal]

New submission from Prashant Kurnawal:

I have embedded python3.3 in my application.
I got a crash when I ran a python script containing sample TK window creation code in it.
 
On interpreter shutdown, all strings are released (through _PyUnicode_ClearStaticStrings). (I Found this description in one of the comments of object.h header file)
 
When I tried to debug python source, I found a defect in _PyUnicode_ClearStaticStrings() method.
 
Existing function definition in python3.3 source (unicodeobject.c) is as follows

void _PyUnicode_ClearStaticStrings()
{
     _Py_Identifier *i;
      for (i = static_strings; i; i = i->next) {
           Py_DECREF(i->object);
           i->object = NULL;
           i->next = NULL;
      }
}
 
Here, for loop will not free all the static strings. It will free only the first static string in the list.
This loop needs to be corrected.
 
I corrected the loop in following way and its working fine for me.
 
void _PyUnicode_ClearStaticStrings()
{
    _Py_Identifier *i;
    while(static_strings->next != NULL)
    {
        i = static_strings;
        static_strings = static_strings->next;
        Py_DECREF(i->object);
        i->object = NULL;
        i->next = NULL;
    }
   
    Py_DECREF(static_strings->object);
    static_strings->object = NULL;
    static_strings = NULL;
}
 
Is this a bug or it is done so intentionally..?

----------
components: None
files: unicodeobject.c
messages: 179432
nosy: benjamin.peterson, brett.cannon, georg.brandl, goodger, larry, prashantkurnawal, python-dev
priority: normal
severity: normal
status: open
title: Bug in _PyUnicode_ClearStaticStrings() method of unicodeobject.c
type: crash
versions: Python 3.3
Added file: http://bugs.python.org/file28646/unicodeobject.c

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue16906>
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