[ python-Bugs-1281408 ] Py_BuildValue k format units don't work with big values

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Bugs item #1281408, was opened at 2005-09-04 00:12
Message generated for change (Comment added) made by loewis
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Category: Python Interpreter Core
Group: Python 2.4
Status: Open
Resolution: None
Priority: 5
Submitted By: Adal Chiriliuc (adalx)
>Assigned to: Reinhold Birkenfeld (birkenfeld)
Summary: Py_BuildValue k format units don't work with big values

Initial Comment:
Python 2.4 on Windows XP SP2

Consider this code:

unsigned long x = 0xaabbccdd;
PyObject* v = Py_BuildValue("k", x);
unsigned long y = PyLong_AsUnsignedLong(v);

y will be equal with -1 because PyLong_AsUnsignedLong
will raise an OverflowError since Py_BuildValue doesn't
create a long for the "k" format unit, but an int which
will be interpreted as a negative number.

The K format seems to have the same error,
PyLong_FromLongLong is used instead of
PyLong_FromUnsignedLongLong.

The do_mkvalue function from mod_support.c must be
fixed to use PyLong_FromUnsignedLong instead of
PyInt_FromLong for "k".

Also, the BHLkK  format units for Py_BuildValue should
be documented. In my Python 2.4 manual they do not appear.

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>Comment By: Martin v. Löwis (loewis)
Date: 2005-11-13 11:31

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The patch looks wrong: for 'I' (capital i), you va_arg
unsigned long; I think 'I' should do unsigned int instead.

A minor nit: why does it move the 'l' case (lower L)?

Apart from that, the patch looks fine.

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Comment By: Reinhold Birkenfeld (birkenfeld)
Date: 2005-11-11 09:45

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Ping!

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Comment By: Reinhold Birkenfeld (birkenfeld)
Date: 2005-09-18 12:07

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Attaching patch (including doc changes). For I and k, it
creates an int if it fits, else a long.

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Comment By: Martin v. Löwis (loewis)
Date: 2005-09-18 10:59

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I'm not sure what it should do: the other option would be to
create an int if it fits, else a long. For 2.4.x atleast,
this would give better backwards compatibility given the
status quo.

I certainly agree that the documentation should be updated.
Patches are welcome.

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Comment By: Reinhold Birkenfeld (birkenfeld)
Date: 2005-09-14 22:02

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I think you're right. Do you too, Martin?

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