Noise: Prevent unittest crash caused by division by zero

SmallJoker · SmallJoker · commit 765fd9a0bc0b · 2017-07-29T19:01:14.000+02:00
diff --git a/src/noise.cpp b/src/noise.cpp
@@ -130,7 +130,9 @@ s32 PcgRandom::range(s32 min, s32 max)
 	if (max < min)
 		throw PrngException("Invalid range (max < min)");
 
-	u32 bound = max - min + 1;
+	// We have to cast to s64 because otherwise this could overflow,
+	// and signed overflow is undefined behavior.
+	u32 bound = (s64)max - (s64)min + 1;
 	return range(bound) + min;
 }
 

Original file line number	Diff line number	Diff line change
`@@ -130,7 +130,9 @@ s32 PcgRandom::range(s32 min, s32 max)`
`130`	`130`	`if (max < min)`
`131`	`131`	`throw PrngException("Invalid range (max < min)");`
`132`	`132`
`133`		`- u32 bound = max - min + 1;`
	`133`	`+ // We have to cast to s64 because otherwise this could overflow,`
	`134`	`+ // and signed overflow is undefined behavior.`
	`135`	`+ u32 bound = (s64)max - (s64)min + 1;`
`134`	`136`	`return range(bound) + min;`
`135`	`137`	`}`
`136`	`138`