[Patches] [ python-Patches-1703286 ] bug fix: ctypes truncates 64-bit pointers

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Patches item #1703286, was opened at 2007-04-18 15:09
Message generated for change (Comment added) made by nnorwitz
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Category: Core (C code)
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Alexander Belopolsky (belopolsky)
>Assigned to: Thomas Heller (theller)
Summary: bug fix: ctypes truncates 64-bit pointers

Initial Comment:
At several places _ctypes module converts a python integer to a void* pointer by first extracting an argument into an int.  Attached patch changes int to Py_ssize_t that is guaranteed to be wide enough to hold a pointer. 

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>Comment By: Neal Norwitz (nnorwitz)
Date: 2007-04-18 23:49

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Thomas would be the best person to answer you question about where it
should go.  Maybe he has some other ideas how to test this.

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Comment By: Alexander Belopolsky (belopolsky)
Date: 2007-04-18 23:44

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Here are (failing) test cases:

Python 2.5 (r25:51908, Oct  4 2006, 18:25:28) 
[GCC 3.4.4 20050721 (Red Hat 3.4.4-2)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> dlopen('libc.so.6')
182896775816
>>> dlclose(_)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: signed integer is greater than maximum
>>> dlsym(_, 'printf')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: signed integer is greater than maximum
>>> call_function(_, ()) # pretend that _ is a function pointer
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: signed integer is greater than maximum
>>> call_cdeclfunction(_, ()) # pretend that _ is a function pointer
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: signed integer is greater than maximum


With the patch:

>>> from _ctypes import *
>>> dlopen('libc.so.6')
182894214624
>>> dlclose(_)

I don't know how to meaningfully exercise call_function and
call_cdeclfunction to trigger the bug because in the default (small memory)
model on AMD64 function pointers always fit into 32 bits.  Maybe a
pseudo-function pointer created by an ffi callback can be used for this
purpose.

I am not sure where these test belong in the testsuit.  Maybe in
ctypes/test/test_loading.py? 





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Comment By: Neal Norwitz (nnorwitz)
Date: 2007-04-18 22:56

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Thanks for the patch.  The changes look correct, however, can you create a
test for these cases?

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