Merge pull request #39 from aave/fix/38-low-decimal-tokens

Fix/38 low decimal tokens

contracts/incentives-v2/DistributionManagerV2.sol

@@ -2,6 +2,7 @@ pragma solidity 0.8.10;
 
 import {IAaveDistributionManagerV2} from './interfaces/IAaveDistributionManagerV2.sol';
 import {DistributionTypesV2} from './libraries/DistributionTypesV2.sol';
+import {IERC20Detailed} from '@aave/core-v3/contracts/dependencies/openzeppelin/contracts/IERC20Detailed.sol';
 
 /**
  * @title DistributionManagerV2
@@ -20,13 +21,12 @@ abstract contract DistributionManagerV2 is IAaveDistributionManagerV2 {
   struct AssetData {
     mapping(address => RewardData) rewards;
     address[] availableRewards;
+    uint8 decimals;
   }
 
   // manager of incentives
   address public immutable EMISSION_MANAGER;
 
-  uint8 public constant PRECISION = 18;
-
   // asset => AssetData
   mapping(address => AssetData) internal _assets;
 
@@ -148,6 +148,8 @@ abstract contract DistributionManagerV2 is IAaveDistributionManagerV2 {
    **/
   function _configureAssets(DistributionTypesV2.RewardsConfigInput[] memory rewardsInput) internal {
     for (uint256 i = 0; i < rewardsInput.length; i++) {
+      _assets[rewardsInput[i].asset].decimals = IERC20Detailed(rewardsInput[i].asset).decimals();
+
       RewardData storage rewardConfig = _assets[rewardsInput[i].asset].rewards[
         rewardsInput[i].reward
       ];
@@ -168,7 +170,8 @@ abstract contract DistributionManagerV2 is IAaveDistributionManagerV2 {
         rewardsInput[i].asset,
         rewardsInput[i].reward,
         rewardConfig,
-        rewardsInput[i].totalSupply
+        rewardsInput[i].totalSupply,
+        _assets[rewardsInput[i].asset].decimals
       );
 
       // Configure emission and distribution end of the reward per asset
@@ -189,14 +192,16 @@ abstract contract DistributionManagerV2 is IAaveDistributionManagerV2 {
    * @param asset The address of the asset being updated
    * @param reward The address of the reward being updated
    * @param rewardConfig Storage pointer to the distribution's reward config
-   * @param totalSupply Current total of staked _assets for this distribution
+   * @param totalSupply Current total of underlying assets for this distribution
+   * @param decimals The decimals of the underlying asset
    * @return The new distribution index
    **/
   function _updateAssetStateInternal(
     address asset,
     address reward,
     RewardData storage rewardConfig,
-    uint256 totalSupply
+    uint256 totalSupply,
+    uint8 decimals
   ) internal returns (uint256) {
     uint256 oldIndex = rewardConfig.index;
 
@@ -209,7 +214,8 @@ abstract contract DistributionManagerV2 is IAaveDistributionManagerV2 {
       rewardConfig.emissionPerSecond,
       rewardConfig.lastUpdateTimestamp,
       rewardConfig.distributionEnd,
-      totalSupply
+      totalSupply,
+      decimals
     );
 
     if (newIndex != oldIndex) {
@@ -245,11 +251,17 @@ abstract contract DistributionManagerV2 is IAaveDistributionManagerV2 {
     uint256 userIndex = rewardData.usersIndex[user];
     uint256 accruedRewards = 0;
 
-    uint256 newIndex = _updateAssetStateInternal(asset, reward, rewardData, totalSupply);
+    uint256 newIndex = _updateAssetStateInternal(
+      asset,
+      reward,
+      rewardData,
+      totalSupply,
+      _assets[asset].decimals
+    );
 
     if (userIndex != newIndex) {
       if (userBalance != 0) {
-        accruedRewards = _getRewards(userBalance, newIndex, userIndex);
+        accruedRewards = _getRewards(userBalance, newIndex, userIndex, _assets[asset].decimals);
       }
 
       rewardData.usersIndex[user] = newIndex;
@@ -259,6 +271,13 @@ abstract contract DistributionManagerV2 is IAaveDistributionManagerV2 {
     return accruedRewards;
   }
 
+  /**
+   * @dev Iterates and updates all rewards of an asset that belongs to an user
+   * @param asset The address of the reference asset of the distribution
+   * @param user The user address
+   * @param userBalance The current user asset balance
+   * @param totalSupply Total supply of the asset
+   **/
   function _updateUserRewardsPerAssetInternal(
     address asset,
     address user,
@@ -370,31 +389,34 @@ abstract contract DistributionManagerV2 is IAaveDistributionManagerV2 {
     DistributionTypesV2.UserAssetStatsInput memory stake
   ) internal view returns (uint256) {
     RewardData storage rewardData = _assets[stake.underlyingAsset].rewards[reward];
-
+    uint8 assetDecimals = _assets[stake.underlyingAsset].decimals;
     uint256 assetIndex = _getAssetIndex(
       rewardData.index,
       rewardData.emissionPerSecond,
       rewardData.lastUpdateTimestamp,
       rewardData.distributionEnd,
-      stake.totalSupply
+      stake.totalSupply,
+      assetDecimals
     );
 
-    return _getRewards(stake.userBalance, assetIndex, rewardData.usersIndex[user]);
+    return _getRewards(stake.userBalance, assetIndex, rewardData.usersIndex[user], assetDecimals);
   }
 
   /**
    * @dev Internal function for the calculation of user's rewards on a distribution
-   * @param principalUserBalance Amount staked by the user on a distribution
+   * @param principalUserBalance Balance of the user asset on a distribution
    * @param reserveIndex Current index of the distribution
    * @param userIndex Index stored for the user, representation his staking moment
+   * @param decimals The decimals of the underlying asset
    * @return The rewards
    **/
   function _getRewards(
     uint256 principalUserBalance,
     uint256 reserveIndex,
-    uint256 userIndex
+    uint256 userIndex,
+    uint8 decimals
   ) internal pure returns (uint256) {
-    return (principalUserBalance * (reserveIndex - userIndex)) / 10**uint256(PRECISION);
+    return (principalUserBalance * (reserveIndex - userIndex)) / 10**decimals;
   }
 
   /**
@@ -403,14 +425,16 @@ abstract contract DistributionManagerV2 is IAaveDistributionManagerV2 {
    * @param emissionPerSecond Representing the total rewards distributed per second per asset unit, on the distribution
    * @param lastUpdateTimestamp Last moment this distribution was updated
    * @param totalBalance of tokens considered for the distribution
+   * @param decimals The decimals of the underlying asset
    * @return The new index.
    **/
   function _getAssetIndex(
     uint256 currentIndex,
     uint256 emissionPerSecond,
     uint128 lastUpdateTimestamp,
     uint256 distributionEnd,
-    uint256 totalBalance
+    uint256 totalBalance,
+    uint8 decimals
   ) internal view returns (uint256) {
     if (
       emissionPerSecond == 0 ||
@@ -425,7 +449,7 @@ abstract contract DistributionManagerV2 is IAaveDistributionManagerV2 {
       ? distributionEnd
       : block.timestamp;
     uint256 timeDelta = currentTimestamp - lastUpdateTimestamp;
-    return (emissionPerSecond * timeDelta * (10**uint256(PRECISION))) / totalBalance + currentIndex;
+    return (emissionPerSecond * timeDelta * (10**decimals)) / totalBalance + currentIndex;
   }
 
   /**
@@ -439,4 +463,9 @@ abstract contract DistributionManagerV2 is IAaveDistributionManagerV2 {
     view
     virtual
     returns (DistributionTypesV2.UserAssetStatsInput[] memory userState);
+
+  /// @inheritdoc IAaveDistributionManagerV2
+  function getAssetDecimals(address asset) external view returns (uint8) {
+    return _assets[asset].decimals;
+  }
 }

contracts/incentives-v2/interfaces/IAaveDistributionManagerV2.sol

@@ -118,8 +118,9 @@ interface IAaveDistributionManagerV2 {
     returns (address[] memory, uint256[] memory);
 
   /**
-   * @dev Returns the precision to calculate the distribution delta
-   * @return The precision of the calculation
+   * @dev Returns the decimals of an asset to calculate the distribution delta
+   * @param asset The address to retrieve decimals saved at storage
+   * @return The decimals of an underlying asset
    */
-  function PRECISION() external view returns (uint8);
+  function getAssetDecimals(address asset) external view returns (uint8);
 }