Merge pull request #191 from m1el/fuzz-rem-overflows

Fixed a few int overflows

Author: alexcrichton

src/math/rem_pio2.rs

@@ -179,29 +179,44 @@ pub(crate) fn rem_pio2(x: f64) -> (i32, f64, f64) {
         i -= 1;
     }
     let mut ty = [0.0; 3];
-    let n = rem_pio2_large(&tx[..=i], &mut ty, ((ix >> 20) - (0x3ff + 23)) as i32, 1);
+    let n = rem_pio2_large(&tx[..=i], &mut ty, ((ix as i32) >> 20) - (0x3ff + 23), 1);
     if sign != 0 {
         return (-n, -ty[0], -ty[1]);
     }
     (n, ty[0], ty[1])
 }
 
-#[test]
-fn test_near_pi() {
-    assert_eq!(
-        rem_pio2(3.141592025756836),
-        (2, -6.278329573009626e-7, -2.1125998133974653e-23)
-    );
-    assert_eq!(
-        rem_pio2(3.141592033207416),
-        (2, -6.20382377148128e-7, -2.1125998133974653e-23)
-    );
-    assert_eq!(
-        rem_pio2(3.141592144966125),
-        (2, -5.086236681942706e-7, -2.1125998133974653e-23)
-    );
-    assert_eq!(
-        rem_pio2(3.141592979431152),
-        (2, 3.2584135866119817e-7, -2.1125998133974653e-23)
-    );
+#[cfg(test)]
+mod tests {
+    use super::rem_pio2;
+
+    #[test]
+    fn test_near_pi() {
+        assert_eq!(
+            rem_pio2(3.141592025756836),
+            (2, -6.278329573009626e-7, -2.1125998133974653e-23)
+        );
+        assert_eq!(
+            rem_pio2(3.141592033207416),
+            (2, -6.20382377148128e-7, -2.1125998133974653e-23)
+        );
+        assert_eq!(
+            rem_pio2(3.141592144966125),
+            (2, -5.086236681942706e-7, -2.1125998133974653e-23)
+        );
+        assert_eq!(
+            rem_pio2(3.141592979431152),
+            (2, 3.2584135866119817e-7, -2.1125998133974653e-23)
+        );
+    }
+
+    #[test]
+    fn test_overflow_b9b847() {
+        let _ = rem_pio2(-3054214.5490637687);
+    }
+
+    #[test]
+    fn test_overflow_4747b9() {
+        let _ = rem_pio2(917340800458.2274);
+    }
 }

src/math/rem_pio2_large.rs

@@ -256,7 +256,7 @@ pub(crate) fn rem_pio2_large(x: &[f64], y: &mut [f64], e0: i32, prec: usize) ->
     let jv = jv as usize;
 
     /* set up f[0] to f[jx+jk] where f[jx+jk] = ipio2[jv+jk] */
-    let mut j = (jv - jx) as i32;
+    let mut j = (jv as i32) - (jx as i32);
     let m = jx + jk;
     for i in 0..=m {
         i!(f, i, =, if j < 0 {

src/math/remquo.rs

@@ -85,7 +85,8 @@ pub fn remquo(mut x: f64, mut y: f64) -> (f64, i32) {
     }
     if ex == ey || (ex + 1 == ey && (2.0 * x > y || (2.0 * x == y && (q % 2) != 0))) {
         x -= y;
-        q += 1;
+        // TODO: this matches musl behavior, but it is incorrect
+        q = q.wrapping_add(1);
     }
     q &= 0x7fffffff;
     let quo = if sx ^ sy { -(q as i32) } else { q as i32 };
@@ -95,3 +96,14 @@ pub fn remquo(mut x: f64, mut y: f64) -> (f64, i32) {
         (x, quo)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::remquo;
+
+    #[test]
+    fn test_q_overflow() {
+        // 0xc000000000000001, 0x04c0000000000004
+        let _ = remquo(-2.0000000000000004, 8.406091369059082e-286);
+    }
+}