From: Tim Peters <tim.peters@gmail.com>
Date: Thu, 21 Nov 2002 22:26:37 +0000 (+0000)
Subject: float_int():  Some systems raise an exception if a double is cast to
X-Git-Tag: v2.3c1~3322
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=7d791240c0858f9cf508234c255d2ca4dabd6088;p=thirdparty%2FPython%2Fcpython.git

float_int():  Some systems raise an exception if a double is cast to
long but the double is too big to fit in a long.  Prevent that.  This
closes some recent bug or patch on SF, but SF is down now so I can't
say which.

Bugfix candidate.
---

diff --git a/Objects/floatobject.c b/Objects/floatobject.c
index 129f5bdc5f89..cd283493ba7f 100644
--- a/Objects/floatobject.c
+++ b/Objects/floatobject.c
@@ -653,23 +653,25 @@ float_int(PyObject *v)
 {
 	double x = PyFloat_AsDouble(v);
 	double wholepart;	/* integral portion of x, rounded toward 0 */
-	long aslong;		/* (long)wholepart */
 
 	(void)modf(x, &wholepart);
-#ifdef RISCOS
-	/* conversion from floating to integral type would raise exception */
-	if (wholepart>LONG_MAX || wholepart<LONG_MIN) {
-		return float_long(v);
-	}
-#endif
-	/* doubles may have more bits than longs, or vice versa; and casting
-	   to long may yield gibberish in either case.  What really matters
-	   is whether converting back to double again reproduces what we
-	   started with. */
-	aslong = (long)wholepart;
-	if ((double)aslong == wholepart)
+	/* Try to get out cheap if this fits in a Python int.  The attempt
+	 * to cast to long must be protected, as C doesn't define what
+	 * happens if the double is too big to fit in a long.  Some rare
+	 * systems raise an exception then (RISCOS was mentioned as one,
+	 * and someone using a non-default option on Sun also bumped into
+	 * that).  Note that checking for >= and <= LONG_{MIN,MAX} would
+	 * still be vulnerable:  if a long has more bits of precision than
+	 * a double, casting MIN/MAX to double may yield an approximation,
+	 * and if that's rounded up, then, e.g., wholepart=LONG_MAX+1 would
+	 * yield true from the C expression wholepart<=LONG_MAX, despite
+	 * that wholepart is actually greater than LONG_MAX.
+	 */
+	if (LONG_MIN < wholepart && wholepart < LONG_MAX) {
+		const long aslong = (long)wholepart;
 		return PyInt_FromLong(aslong);
-	return float_long(v);
+	}
+	return PyLong_FromDouble(wholepart);
 }
 
 static PyObject *