[Python-Dev] [Python 2.4] PyInt_FromLong returning NULL (original) (raw)

Tim Peters tim.peters at gmail.com
Tue Dec 7 19:17:19 CET 2004

[Tim]

... but as a pragmatic matter PyIntFromLong(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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