Use storage slot for upgradeable contracts

Author: ScreamingHawk

src/contracts/mocks/ERC1155MetadataUpgradeableMock.sol

@@ -72,6 +72,6 @@ contract ERC1155MetadataUpgradeableMockV2 is ERC1155MetadataUpgradeableMock {
   }
 
   function uri(uint256 _id) public override view returns (string memory) {
-    return string(abi.encodePacked(baseURI, _uint2str(idMapping[_id]))); // Removes .json extension, swaps ids
+    return string(abi.encodePacked(baseURI(), _uint2str(idMapping[_id]))); // Removes .json extension, swaps ids
   }
 }

src/contracts/tokens/ERC1155/ERC1155Meta.sol

@@ -294,12 +294,13 @@ contract ERC1155Meta is ERC1155, SignatureValidator {
     // Complete data to pass to signer verifier
     bytes memory fullData = abi.encodePacked(_encMembers, nonce, signedData);
 
-    //Update signature nonce
+    // Verify if _from is the signer
+    require(isValidSignature(_signer, hash, fullData, sig), "ERC1155Meta#_signatureValidation: INVALID_SIGNATURE");
+
+    // Update signature nonce
     nonces[_signer] = nonce + 1;
     emit NonceChange(_signer, nonce + 1);
 
-    // Verify if _from is the signer
-    require(isValidSignature(_signer, hash, fullData, sig), "ERC1155Meta#_signatureValidation: INVALID_SIGNATURE");
     return signedData;
   }
 

src/contracts/tokens/ERC1155PackedBalanceUpgradeable/ERC1155MetaPackedBalanceUpgradeable.sol

@@ -6,7 +6,7 @@ import "../../interfaces/IERC20.sol";
 import "../../interfaces/IERC1155.sol";
 import "../../utils/LibBytes.sol";
 import "../../utils/SignatureValidator.sol";
-
+import '../../utils/StorageSlot.sol';
 
 /**
  * @dev ERC-1155 with native metatransaction methods. These additional functions allow users
@@ -45,7 +45,7 @@ contract ERC1155MetaPackedBalanceUpgradeable is ERC1155PackedBalanceUpgradeable,
   }
 
   // Signature nonce per address
-  mapping (address => uint256) internal nonces;
+  bytes32 constant private _NONCES_SLOT_KEY = keccak256("0xsequence.ERC1155MetaPackedBalanceUpgradeable.nonces");
 
 
   /***********************************|
@@ -227,7 +227,7 @@ contract ERC1155MetaPackedBalanceUpgradeable is ERC1155PackedBalanceUpgradeable,
     );
 
     // Update operator status
-    operators[_owner][_operator] = _approved;
+    _setOperator(_owner, _operator, _approved);
 
     // Emit event
     emit ApprovalForAll(_owner, _operator, _approved);
@@ -284,8 +284,8 @@ contract ERC1155MetaPackedBalanceUpgradeable is ERC1155PackedBalanceUpgradeable,
     (sig, signedData) = abi.decode(_sigData, (bytes, bytes));
 
     // Get current nonce and nonce used for signature
-    uint256 currentNonce = nonces[_signer];        // Lowest valid nonce for signer
-    uint256 nonce = uint256(sig.readBytes32(65));  // Nonce passed in the signature object
+    uint256 currentNonce = _getNonce(_signer);   // Lowest valid nonce for signer
+    uint256 nonce = uint256(sig.readBytes32(65)); // Nonce passed in the signature object
 
     // Verify if nonce is valid
     require(
@@ -300,8 +300,9 @@ contract ERC1155MetaPackedBalanceUpgradeable is ERC1155PackedBalanceUpgradeable,
     bytes memory fullData = abi.encodePacked(_encMembers, nonce, signedData);
 
     //Update signature nonce
-    nonces[_signer] = nonce + 1;
-    emit NonceChange(_signer, nonce + 1);
+    nonce++;
+    _setNonce(_signer, nonce);
+    emit NonceChange(_signer, nonce);
 
     // Verify if _from is the signer
     require(isValidSignature(_signer, hash, fullData, sig), "ERC1155MetaPackedBalance#_signatureValidation: INVALID_SIGNATURE");
@@ -315,7 +316,26 @@ contract ERC1155MetaPackedBalanceUpgradeable is ERC1155PackedBalanceUpgradeable,
   function getNonce(address _signer)
     public view returns (uint256 nonce)
   {
-    return nonces[_signer];
+    return _getNonce(_signer);
+  }
+
+  /**
+   * @notice Returns the current nonce associated with a given address
+   * @param _signer Address to query signature nonce for
+   */
+  function _getNonce(address _signer)
+    internal view returns (uint256 nonce)
+  {
+    return StorageSlot.getUint256Slot(keccak256(abi.encodePacked(_NONCES_SLOT_KEY, _signer))).value;
+  }
+
+  /**
+   * @notice Sets the nonce associated with a given address
+   * @param _signer Address to set signature nonce for
+   * @param _nonce Nonce value to set
+   */
+  function _setNonce(address _signer, uint256 _nonce) internal {
+    StorageSlot.getUint256Slot(keccak256(abi.encodePacked(_NONCES_SLOT_KEY, _signer))).value = _nonce;
   }
 
 

src/contracts/tokens/ERC1155PackedBalanceUpgradeable/ERC1155MintBurnPackedBalanceUpgradeable.sol

@@ -51,7 +51,7 @@ contract ERC1155MintBurnPackedBalanceUpgradeable is ERC1155PackedBalanceUpgradea
       (uint256 bin, uint256 index) = getIDBinIndex(_ids[0]);
 
       // Balance for current bin in memory (initialized with first transfer)
-      uint256 balTo = _viewUpdateBinValue(balances[_to][bin], index, _amounts[0], Operations.Add);
+      uint256 balTo = _viewUpdateBinValue(_getBalance(_to, bin), index, _amounts[0], Operations.Add);
 
       // Number of transfer to execute
       uint256 nTransfer = _ids.length;
@@ -65,8 +65,8 @@ contract ERC1155MintBurnPackedBalanceUpgradeable is ERC1155PackedBalanceUpgradea
         // If new bin
         if (bin != lastBin) {
           // Update storage balance of previous bin
-          balances[_to][lastBin] = balTo;
-          balTo = balances[_to][bin];
+          _setBalance(_to, lastBin, balTo);
+          balTo = _getBalance(_to, bin);
 
           // Bin will be the most recent bin
           lastBin = bin;
@@ -77,7 +77,7 @@ contract ERC1155MintBurnPackedBalanceUpgradeable is ERC1155PackedBalanceUpgradea
       }
 
       // Update storage of the last bin visited
-      balances[_to][bin] = balTo;
+      _setBalance(_to, bin, balTo);
     }
 
     // //Emit event

src/contracts/tokens/ERC1155PackedBalanceUpgradeable/ERC1155PackedBalanceUpgradeable.sol

@@ -6,6 +6,7 @@ import "../../interfaces/IERC1155.sol";
 import "../../utils/Address.sol";
 import "../../utils/ContextUpgradeable.sol";
 import "../../utils/ERC165.sol";
+import '../../utils/StorageSlot.sol';
 
 /**
  * @dev Implementation of Multi-Token Standard contract. This implementation of the ERC-1155 standard
@@ -35,10 +36,10 @@ contract ERC1155PackedBalanceUpgradeable is ContextUpgradeable, IERC1155, ERC165
   enum Operations { Add, Sub }
 
   // Token IDs balances ; balances[address][id] => balance (using array instead of mapping for efficiency)
-  mapping (address => mapping(uint256 => uint256)) internal balances;
+  bytes32 constant private _BALANCES_SLOT_KEY = keccak256("0xsequence.ERC1155PackedBalanceUpgradeable.balances");
 
   // Operators
-  mapping (address => mapping(address => bool)) internal operators;
+  bytes32 constant private _OPERATORS_SLOT_KEY = keccak256("0xsequence.ERC1155PackedBalanceUpgradeable.operators");
 
 
   /***********************************|
@@ -140,8 +141,8 @@ contract ERC1155PackedBalanceUpgradeable is ContextUpgradeable, IERC1155, ERC165
       (uint256 bin, uint256 index) = getIDBinIndex(_ids[0]);
 
       // Balance for current bin in memory (initialized with first transfer)
-      uint256 balFrom = _viewUpdateBinValue(balances[_from][bin], index, _amounts[0], Operations.Sub);
-      uint256 balTo = _viewUpdateBinValue(balances[_to][bin], index, _amounts[0], Operations.Add);
+      uint256 balFrom = _viewUpdateBinValue(_getBalance(_from, bin), index, _amounts[0], Operations.Sub);
+      uint256 balTo = _viewUpdateBinValue(_getBalance(_to, bin), index, _amounts[0], Operations.Add);
 
       // Last bin updated
       uint256 lastBin = bin;
@@ -152,11 +153,11 @@ contract ERC1155PackedBalanceUpgradeable is ContextUpgradeable, IERC1155, ERC165
         // If new bin
         if (bin != lastBin) {
           // Update storage balance of previous bin
-          balances[_from][lastBin] = balFrom;
-          balances[_to][lastBin] = balTo;
+          _setBalance(_from, lastBin, balFrom);
+          _setBalance(_to, lastBin, balTo);
 
-          balFrom = balances[_from][bin];
-          balTo = balances[_to][bin];
+          balFrom = _getBalance(_from, bin);
+          balTo = _getBalance(_to, bin);
 
           // Bin will be the most recent bin
           lastBin = bin;
@@ -168,8 +169,8 @@ contract ERC1155PackedBalanceUpgradeable is ContextUpgradeable, IERC1155, ERC165
       }
 
       // Update storage of the last bin visited
-      balances[_from][bin] = balFrom;
-      balances[_to][bin] = balTo;
+      _setBalance(_from, bin, balFrom);
+      _setBalance(_to, bin, balTo);
 
     // If transfer to self, just make sure all amounts are valid
     } else {
@@ -209,7 +210,7 @@ contract ERC1155PackedBalanceUpgradeable is ContextUpgradeable, IERC1155, ERC165
     external override
   {
     // Update operator status
-    operators[_msgSender()][_operator] = _approved;
+    _setOperator(_msgSender(), _operator, _approved);
     emit ApprovalForAll(_msgSender(), _operator, _approved);
   }
 
@@ -222,7 +223,7 @@ contract ERC1155PackedBalanceUpgradeable is ContextUpgradeable, IERC1155, ERC165
   function isApprovedForAll(address _owner, address _operator)
     public override view returns (bool isOperator)
   {
-    return operators[_owner][_operator];
+    return _getOperator(_owner, _operator);
   }
 
 
@@ -244,7 +245,7 @@ contract ERC1155PackedBalanceUpgradeable is ContextUpgradeable, IERC1155, ERC165
 
     //Get bin and index of _id
     (bin, index) = getIDBinIndex(_id);
-    return getValueInBin(balances[_owner][bin], index);
+    return getValueInBin(_getBalance(_owner, bin), index);
   }
 
   /**
@@ -261,7 +262,7 @@ contract ERC1155PackedBalanceUpgradeable is ContextUpgradeable, IERC1155, ERC165
 
     // First values
     (uint256 bin, uint256 index) = getIDBinIndex(_ids[0]);
-    uint256 balance_bin = balances[_owners[0]][bin];
+    uint256 balance_bin = _getBalance(_owners[0], bin);
     uint256 last_bin = bin;
 
     // Initialization
@@ -274,7 +275,7 @@ contract ERC1155PackedBalanceUpgradeable is ContextUpgradeable, IERC1155, ERC165
 
       // SLOAD if bin changed for the same owner or if owner changed
       if (bin != last_bin || _owners[i-1] != _owners[i]) {
-        balance_bin = balances[_owners[i]][bin];
+        balance_bin = _getBalance(_owners[i], bin);
         last_bin = bin;
       }
 
@@ -308,7 +309,7 @@ contract ERC1155PackedBalanceUpgradeable is ContextUpgradeable, IERC1155, ERC165
     (bin, index) = getIDBinIndex(_id);
 
     // Update balance
-    balances[_address][bin] = _viewUpdateBinValue(balances[_address][bin], index, _amount, _operation);
+    _setBalance(_address, bin, _viewUpdateBinValue(_getBalance(_address, bin), index, _amount, _operation));
   }
 
   /**
@@ -379,6 +380,26 @@ contract ERC1155PackedBalanceUpgradeable is ContextUpgradeable, IERC1155, ERC165
     return (_binValues >> rightShift) & mask;
   }
 
+  /***********************************|
+  |         Storage Functions         |
+  |__________________________________*/
+
+  function _getBalance(address _owner, uint256 _id) internal view returns (uint256) {
+    return StorageSlot.getUint256Slot(keccak256(abi.encodePacked(_BALANCES_SLOT_KEY, _owner, _id))).value;
+  }
+
+  function _setBalance(address _owner, uint256 _id, uint256 _balance) internal {
+    StorageSlot.getUint256Slot(keccak256(abi.encodePacked(_BALANCES_SLOT_KEY, _owner, _id))).value = _balance;
+  }
+
+  function _getOperator(address _owner, address _operator) internal view returns (bool) {
+    return StorageSlot.getBooleanSlot(keccak256(abi.encodePacked(_OPERATORS_SLOT_KEY, _owner, _operator))).value;
+  }
+
+  function _setOperator(address _owner, address _operator, bool _approved) internal {
+    StorageSlot.getBooleanSlot(keccak256(abi.encodePacked(_OPERATORS_SLOT_KEY, _owner, _operator))).value = _approved;
+  }
+
 
   /***********************************|
   |          ERC165 Functions         |

src/contracts/tokens/ERC1155Upgradeable/ERC1155MetaUpgradeable.sol

@@ -6,6 +6,7 @@ import "../../interfaces/IERC20.sol";
 import "../../interfaces/IERC1155.sol";
 import "../../utils/LibBytes.sol";
 import "../../utils/SignatureValidator.sol";
+import '../../utils/StorageSlot.sol';
 
 /**
  * @dev ERC-1155 with native metatransaction methods. These additional functions allow users
@@ -41,8 +42,7 @@ contract ERC1155MetaUpgradeable is ERC1155Upgradeable, SignatureValidator {
   }
 
   // Signature nonce per address
-  mapping (address => uint256) internal nonces;
-
+  bytes32 constant private _NONCES_SLOT_KEY = keccak256("0xsequence.ERC1155MetaUpgradeable.nonces");
 
   /***********************************|
   |               Events              |
@@ -223,7 +223,7 @@ contract ERC1155MetaUpgradeable is ERC1155Upgradeable, SignatureValidator {
     );
 
     // Update operator status
-    operators[_owner][_operator] = _approved;
+    _setOperator(_owner, _operator, _approved);
 
     // Emit event
     emit ApprovalForAll(_owner, _operator, _approved);
@@ -279,8 +279,8 @@ contract ERC1155MetaUpgradeable is ERC1155Upgradeable, SignatureValidator {
     (sig, signedData) = abi.decode(_sigData, (bytes, bytes));
 
     // Get current nonce and nonce used for signature
-    uint256 currentNonce = nonces[_signer];        // Lowest valid nonce for signer
-    uint256 nonce = uint256(sig.readBytes32(65));  // Nonce passed in the signature object
+    uint256 currentNonce = _getNonce(_signer);   // Lowest valid nonce for signer
+    uint256 nonce = uint256(sig.readBytes32(65)); // Nonce passed in the signature object
 
     // Verify if nonce is valid
     require(
@@ -294,12 +294,14 @@ contract ERC1155MetaUpgradeable is ERC1155Upgradeable, SignatureValidator {
     // Complete data to pass to signer verifier
     bytes memory fullData = abi.encodePacked(_encMembers, nonce, signedData);
 
-    //Update signature nonce
-    nonces[_signer] = nonce + 1;
-    emit NonceChange(_signer, nonce + 1);
-
     // Verify if _from is the signer
     require(isValidSignature(_signer, hash, fullData, sig), "ERC1155Meta#_signatureValidation: INVALID_SIGNATURE");
+
+    // Update signature nonce
+    nonce++;
+    _setNonce(_signer, nonce);
+    emit NonceChange(_signer, nonce);
+
     return signedData;
   }
 
@@ -310,7 +312,26 @@ contract ERC1155MetaUpgradeable is ERC1155Upgradeable, SignatureValidator {
   function getNonce(address _signer)
     public view returns (uint256 nonce)
   {
-    return nonces[_signer];
+    return _getNonce(_signer);
+  }
+
+  /**
+   * @notice Returns the current nonce associated with a given address
+   * @param _signer Address to query signature nonce for
+   */
+  function _getNonce(address _signer)
+    internal view returns (uint256 nonce)
+  {
+    return StorageSlot.getUint256Slot(keccak256(abi.encodePacked(_NONCES_SLOT_KEY, _signer))).value;
+  }
+
+  /**
+   * @notice Sets the nonce associated with a given address
+   * @param _signer Address to set signature nonce for
+   * @param _nonce Nonce value to set
+   */
+  function _setNonce(address _signer, uint256 _nonce) internal {
+    StorageSlot.getUint256Slot(keccak256(abi.encodePacked(_NONCES_SLOT_KEY, _signer))).value = _nonce;
   }