Extend the supported input range of trade-by-source-amount (reduce th…

…e probability of reverting on overflow)
bancorprotocol · Jan 18, 2024 · 7bb6e3b · 7bb6e3b
1 parent 637a895
commit 7bb6e3b
Show file tree

Hide file tree

Showing 2 changed files with 23 additions and 1 deletion.
diff --git a/contracts/carbon/Strategies.sol b/contracts/carbon/Strategies.sol
@@ -778,7 +778,12 @@ abstract contract Strategies is Initializable {
 
         uint256 temp4 = MathEx.mulDivC(temp1, temp1, factor);
         uint256 temp5 = MathEx.mulDivC(temp3, A, factor);
-        return MathEx.mulDivF(temp2, temp3 / factor, temp4 + temp5);
+
+        (bool safe, uint256 sum) = tryAdd(temp4, temp5);
+        if (safe) {
+            return MathEx.mulDivF(temp2, temp3 / factor, sum);
+        }
+        return temp2 / (A + MathEx.mulDivC(temp1, temp1, temp3));
     }
 
     /**
@@ -972,6 +977,13 @@ abstract contract Strategies is Initializable {
         }
     }
 
+    function tryAdd(uint256 x, uint256 y) private pure returns (bool safe, uint256 sum) {
+        unchecked {
+            sum = x + y;
+            safe = sum >= x;
+        }
+    }
+
     function uncheckedInc(uint256 i) private pure returns (uint256 j) {
         unchecked {
             j = i + 1;

diff --git a/test/carbon/accuracy/data/ExtremeSrcTrade.json b/test/carbon/accuracy/data/ExtremeSrcTrade.json
@@ -5108,5 +5108,15 @@
     "inputAmount": "912345678",
     "implReturn": "11263526807791440437174508207861",
     "specReturn": "11263526807791494477914130651426"
+  },
+  {
+    "liquidity": "969467735247045389207437",
+    "lowestRate": "33333333333333.01391180980424255864136284799315035343170166015625",
+    "highestRate": "198019801980197.408654344705869476683801622129976749420166015625",
+    "marginalRate": "104452559155538.8882958589671163947507815520699425817338168004935",
+    "tradeBy": "SourceAmount",
+    "inputAmount": "15120357940",
+    "implReturn": "924248818871126217204242",
+    "specReturn": "924248818871128843570750.388118986304"
   }
 ]