fix: inconsistent Liquidations in BaseStrategy Emergency Exit Mode (#311

) * fix: inconsistent Liquidations in BaseStrategy Emergency Exit Mode * refactor: move code back into harvest
yearn · May 16, 2021 · 6159b87 · 6159b87
1 parent 35cf726
commit 6159b87
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Showing 2 changed files with 19 additions and 9 deletions.
diff --git a/contracts/BaseStrategy.sol b/contracts/BaseStrategy.sol
@@ -584,13 +584,19 @@ abstract contract BaseStrategy {
      * liquidation. If there is a difference between them, `_loss` indicates whether the
      * difference is due to a realized loss, or if there is some other sitution at play
      * (e.g. locked funds) where the amount made available is less than what is needed.
-     * This function is used during emergency exit instead of `prepareReturn()` to
-     * liquidate all of the Strategy's positions back to the Vault.
      *
      * NOTE: The invariant `_liquidatedAmount + _loss <= _amountNeeded` should always be maintained
      */
     function liquidatePosition(uint256 _amountNeeded) internal virtual returns (uint256 _liquidatedAmount, uint256 _loss);
 
+    /**
+     * Liquidate everything and returns the amount that got freed.
+     * This function is used during emergency exit instead of `prepareReturn()` to
+     * liquidate all of the Strategy's positions back to the Vault.
+     */
+
+    function liquidateAllPositions() internal virtual returns (uint256 _amountFreed);
+
     /**
      * @notice
      *  Provide a signal to the keeper that `tend()` should be called. The
@@ -720,14 +726,13 @@ abstract contract BaseStrategy {
         uint256 debtPayment = 0;
         if (emergencyExit) {
             // Free up as much capital as possible
-            uint256 totalAssets = estimatedTotalAssets();
-            // NOTE: use the larger of total assets or debt outstanding to book losses properly
-            (debtPayment, loss) = liquidatePosition(totalAssets > debtOutstanding ? totalAssets : debtOutstanding);
-            // NOTE: take up any remainder here as profit
-            if (debtPayment > debtOutstanding) {
-                profit = debtPayment.sub(debtOutstanding);
-                debtPayment = debtOutstanding;
+            uint256 amountFreed = liquidateAllPositions();
+            if (amountFreed < debtOutstanding) {
+                loss = debtOutstanding.sub(amountFreed);
+            } else if (amountFreed > debtOutstanding) {
+                profit = amountFreed.sub(debtOutstanding);
             }
+            debtPayment = debtOutstanding.sub(loss);
         } else {
             // Free up returns for Vault to pull
             (profit, loss, debtPayment) = prepareReturn(debtOutstanding);

diff --git a/contracts/test/TestStrategy.sol b/contracts/test/TestStrategy.sol
@@ -125,4 +125,9 @@ contract TestStrategy is BaseStrategyInitializable {
         protected[0] = protectedToken;
         return protected;
     }
+
+    function liquidateAllPositions() internal override returns (uint256 amountFreed) {
+        uint256 totalAssets = want.balanceOf(address(this));
+        amountFreed = totalAssets;
+    }
 }