From f1788d9e7058c3cb80d54277b3260755a6275965 Mon Sep 17 00:00:00 2001
From: nicoo <nicoo@debian.org>
Date: Tue, 16 Jun 2020 01:17:16 +0200
Subject: [PATCH] fixup! factor::numeric::Montgomery: Fix overflow bug

---
 src/uu/factor/src/numeric.rs | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/uu/factor/src/numeric.rs b/src/uu/factor/src/numeric.rs
index 0525e70b6..2d5d1ec21 100644
--- a/src/uu/factor/src/numeric.rs
+++ b/src/uu/factor/src/numeric.rs
@@ -80,16 +80,16 @@ impl Montgomery {
         let (xnm, overflow) = (x as u128).overflowing_add(nm); // x + n*m
         debug_assert_eq!(xnm % (1 << 64), 0);
 
-        if !overflow {
-            let y = (xnm >> 64) as u64 + overflow as u64; // (x + n*m) / R
-            if y >= *n {
-                y - n
-            } else {
-                y
-            }
+        // (x + n*m) / R
+        // in case of overflow, this is (2¹²⁸ + xnm)/2⁶⁴ - n = xnm/2⁶⁴ + (2⁶⁴ - n)
+        let y =
+            (xnm >> 64) as u64 +
+            if !overflow { 0 } else { n.wrapping_neg() };
+
+        if y >= *n {
+            y - n
         } else {
-            // y = (2¹²⁸ + xnm)/2⁶⁴ - n = xnm/2⁶⁴ + (2⁶⁴ - n)
-            (xnm >> 64) as u64 + n.wrapping_neg()
+            y
         }
     }
 }