[Python-Dev] [Python 2.4] PyInt_FromLong returning NULL
Tim Peters
tim.peters at gmail.com
Tue Dec 7 19:17:19 CET 2004
[Tim]
>> ... but as a pragmatic matter PyInt_FromLong(1) can't fail --
[Jim]
> I know. I'm sure that's why we don't bother. But, obviously,
> it can fail.
I disagree -- it's not obvious at all. Looking at the code, it's far
more likely that Andreas misunderstood the cause of the failure than
that PyInt_FromLong(1) actually returned NULL. If it did return NULL,
then it's got to be something as rare as bad code generation (for
reasons I explained earlier), or a non-standard compilation that
fiddled the NSMALLPOSINTS and/or NSMALLNEGINTS #defines to insane
values.
This is the entire expected path in PyInt_FromLong(1):
PyObject *
PyInt_FromLong(long ival)
{
register PyIntObject *v;
#if NSMALLNEGINTS + NSMALLPOSINTS > 0
if (-NSMALLNEGINTS <= ival && ival < NSMALLPOSINTS) {
v = small_ints[ival + NSMALLNEGINTS];
Py_INCREF(v);
#ifdef COUNT_ALLOCS
if (ival >= 0)
quick_int_allocs++;
else
quick_neg_int_allocs++;
#endif
return (PyObject *) v;
}
#endif
It's not possible for that to return NULL -- even if small_ints[] got
corrupted, so that v == NULL, the Py_INCREF(v) would have blown up
before the function could have returned.
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