Forward-port of r52136,52138: a review of overflow-detecting code.
* unified the way intobject, longobject and mystrtoul handle
values around -sys.maxint-1.
* in general, trying to entierely avoid overflows in any computation
involving signed ints or longs is extremely involved. Fixed a few
simple cases where a compiler might be too clever (but that's all
guesswork).
* more overflow checks against bad data in marshal.c.
* 2.5 specific: fixed a number of places that were still confusing int
and Py_ssize_t. Some of them could potentially have caused
"real-world" breakage.
* list.pop(x): fixing overflow issues on x was messy. I just reverted
to PyArg_ParseTuple("n"), which does the right thing. (An obscure
test was trying to give a Decimal to list.pop()... doesn't make
sense any more IMHO)
* trying to write a few tests...
diff --git a/Python/mystrtoul.c b/Python/mystrtoul.c
index 0dda4be..f007057 100644
--- a/Python/mystrtoul.c
+++ b/Python/mystrtoul.c
@@ -195,13 +195,10 @@
return (unsigned long)-1;
}
-/* Checking for overflow in PyOS_strtol is a PITA since C doesn't define
- * anything about what happens when a signed integer operation overflows,
- * and some compilers think they're doing you a favor by being "clever"
- * then. Python assumes a 2's-complement representation, so that the bit
- * pattern for the largest postive signed long is LONG_MAX, and for
- * the smallest negative signed long is LONG_MAX + 1.
+/* Checking for overflow in PyOS_strtol is a PITA; see comments
+ * about PY_ABS_LONG_MIN in longobject.c.
*/
+#define PY_ABS_LONG_MIN (0-(unsigned long)LONG_MIN)
long
PyOS_strtol(char *str, char **ptr, int base)
@@ -224,8 +221,7 @@
if (sign == '-')
result = -result;
}
- else if (sign == '-' && uresult == (unsigned long)LONG_MAX + 1) {
- assert(LONG_MIN == -LONG_MAX-1);
+ else if (sign == '-' && uresult == PY_ABS_LONG_MIN) {
result = LONG_MIN;
}
else {