[issue4606] Passing 'None' if argtype is set to POINTER(...) doesn't always result in NULL

[Thomas Heller]

Thomas Heller <theller at ctypes.org> added the comment:

Andrew McNabb schrieb:
> I just looked at ConvParam in a little more detail, and it seems that
> the problem is caused because setting pa->value.i to 0 only works for
> the lower-order bits.  Apparently the higher order bits in pa->value are
> non-zero when ConvParam is called.  Would it be possible to zero-out
> pa->value at the top of ConvParam (i.e., putting "bzero(&(pa->value),
> sizeof(pa->value)" or something at the top of ConvParam)?  Am I missing
> something about what's in pa before ConvParam is called?

Zeroing out higher order bits wouldn't help because the parameter would
still be passed as int instead as pointer; see the ffi_type field.

However, after thinking the whole issue over for some time I'm now
convinced that this patch is the right approach; even if .from_param()
returns 'None' instead of '0' the former should be accepted as well
because it better represents a NULL pointer anyway.

So I will apply the patch to trunk and 2.6, and forward port to the
python3 branches.  After further testing.

----------
resolution:  -> accepted
versions: +Python 2.7, Python 3.0, Python 3.1, Python 3.2 -Python 2.5

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<http://bugs.python.org/issue4606>
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