Get slot for ERC20 variable from storage layout (#13)

* Get slot for ERC20 variable from storage layout.

* Fix solidity-mapper build for importing library functions.

* Implement lint command in solidity-mapper package.

Co-authored-by: nikugogoi <95nikass@gmail.com>

packages/solidity-mapper/.eslintignore

@@ -0,0 +1,5 @@
+# Don't lint node_modules.
+node_modules
+
+# Don't lint build output.
+dist

packages/solidity-mapper/.eslintrc.json

@@ -0,0 +1,20 @@
+{
+    "env": {
+        "browser": true,
+        "es2021": true
+    },
+    "extends": [
+        "semistandard",
+        "plugin:@typescript-eslint/recommended"
+    ],
+    "parser": "@typescript-eslint/parser",
+    "parserOptions": {
+        "ecmaVersion": 12,
+        "sourceType": "module"
+    },
+    "plugins": [
+        "@typescript-eslint"
+    ],
+    "rules": {
+    }
+}

packages/solidity-mapper/README.md

@@ -17,17 +17,17 @@ $ yarn test
 
 ## Different Types
 
-* Booleans
+* [x] Booleans
-* Integers
+* [x] Integers
-* Fixed Point Numbers
+* [ ] Fixed Point Numbers
-* Address
+* [x] Address
-* Contract Types
+* [ ] Contract Types
-* Fixed-size byte arrays
+* [ ] Fixed-size byte arrays
-* Enums
+* [ ] Enums
-* Function Types
+* [ ] Function Types
-* Arrays
+* [ ] Arrays
-* Structs
+* [ ] Structs
-* Mapping Types
+* [ ] Mapping Types
 
 ## Observations
 

packages/solidity-mapper/package.json

@@ -1,8 +1,7 @@
 {
   "name": "@vulcanize/solidity-mapper",
   "version": "0.1.0",
-  "main": "dist/index.js",
+  "main": "src/index.ts",
-  "types": "dist/index.d.ts",
   "license": "UNLICENSED",
   "devDependencies": {
     "@nomiclabs/hardhat-ethers": "^2.0.2",
@@ -10,7 +9,16 @@
     "@types/chai": "^4.2.18",
     "@types/mocha": "^8.2.2",
     "@types/node": "^15.6.1",
+    "@typescript-eslint/eslint-plugin": "^4.25.0",
+    "@typescript-eslint/parser": "^4.25.0",
     "chai": "^4.3.4",
+    "eslint": "^7.27.0",
+    "eslint-config-semistandard": "^15.0.1",
+    "eslint-config-standard": "^16.0.3",
+    "eslint-plugin-import": "^2.23.3",
+    "eslint-plugin-node": "^11.1.0",
+    "eslint-plugin-promise": "^5.1.0",
+    "eslint-plugin-standard": "^5.0.0",
     "ethereum-waffle": "^3.3.0",
     "ethers": "^5.2.0",
     "hardhat": "^2.3.0",
@@ -19,6 +27,7 @@
   },
   "scripts": {
     "build": "tsc",
-    "test": "hardhat test"
+    "test": "hardhat test",
+    "lint": "eslint ."
   }
 }

packages/solidity-mapper/src/index.ts

@@ -1 +1 @@
-export { getStorageValue, StorageLayout, GetStorageAt } from './storage';
+export { getStorageValue, getStorageInfo, StorageLayout, GetStorageAt } from './storage';

packages/solidity-mapper/src/storage.ts

@@ -1,23 +1,50 @@
 import { utils, BigNumber } from 'ethers';
 
+interface Storage {
+  slot: string;
+  offset: number;
+  type: string;
+  label: string;
+}
+
+interface Type {
+  encoding: string;
+  numberOfBytes: string;
+  label: string;
+}
+
 export interface StorageLayout {
-  storage: [{
+  storage: Storage[];
-    slot: string;
+  types: { [type: string]: Type; }
-    offset: number;
+}
-    type: string;
+
-    label: string;
+export interface StorageInfo extends Storage {
-  }];
+  types: { [type: string]: Type; }
-  types: {
-    [type: string]: {
-      encoding: string;
-      numberOfBytes: string;
-      label: string;
-    }
-  };
 }
 
 export type GetStorageAt = (address: string, position: string) => Promise<string>
 
+/**
+ * Function to get storage information of variable from storage layout.
+ * @param storageLayout
+ * @param variableName
+ */
+export const getStorageInfo = (storageLayout: StorageLayout, variableName: string): StorageInfo => {
+  const { storage, types } = storageLayout;
+  const targetState = storage.find((state) => state.label === variableName)
+
+  // Throw if state variable could not be found in storage layout.
+  if (!targetState) {
+    throw new Error('Variable not present in storage layout.');
+  }
+
+  return {
+    ...targetState,
+    slot: utils.hexlify(BigNumber.from(targetState.slot)),
+    types
+  }
+}
+
 /**
  * Function to get the value from storage for a contract variable.
  * @param address
@@ -26,15 +53,7 @@ export type GetStorageAt = (address: string, position: string) => Promise<string
  * @param variableName
  */
 export const getStorageValue = async (address: string, storageLayout: StorageLayout, getStorageAt: GetStorageAt, variableName: string): Promise<number | string | boolean | undefined> => {
-  const { storage, types } = storageLayout;
+  const { slot, offset, type, types } = getStorageInfo(storageLayout, variableName);
-  const targetState = storage.find((state) => state.label === variableName)
-
-  // Return if state variable could not be found in storage layout.
-  if (!targetState) {
-    return;
-  }
-
-  const { slot, offset, type } = targetState;
   const { encoding, numberOfBytes, label } = types[type]
 
   // Get value according to encoding i.e. how the data is encoded in storage.
@@ -79,7 +98,7 @@ export const getStorageValue = async (address: string, storageLayout: StorageLay
  * @param getStorageAt
  */
 const getInplaceArray = async (address: string, slot: string, offset: number, numberOfBytes: string, getStorageAt: GetStorageAt) => {
-  const value = await getStorageAt(address, BigNumber.from(slot).toHexString());
+  const value = await getStorageAt(address, slot);
   const uintArray = utils.arrayify(value);
 
   // Get value according to offset.
@@ -97,7 +116,7 @@ const getInplaceArray = async (address: string, slot: string, offset: number, nu
  * @param getStorageAt
  */
 const getBytesArray = async (address: string, slot: string, getStorageAt: GetStorageAt) => {
-  let value = await getStorageAt(address, BigNumber.from(slot).toHexString());
+  let value = await getStorageAt(address, slot);
   const uintArray = utils.arrayify(value);
   let length = 0;
 
@@ -122,8 +141,8 @@ const getBytesArray = async (address: string, slot: string, getStorageAt: GetSto
 
   // Compute zero padded hexstring to calculate hashed position of storage.
   // https://github.com/ethers-io/ethers.js/issues/1079#issuecomment-703056242
-  const slotHex = utils.hexZeroPad(BigNumber.from(slot).toHexString(), 32);
+  const paddedSlotHex = utils.hexZeroPad(slot, 32);
-  const position = utils.keccak256(slotHex);
+  const position = utils.keccak256(paddedSlotHex);
 
   // Get value from consecutive storage slots for longer data.
   for(let i = 0; i < length / 32; i++) {

packages/solidity-mapper/tsconfig.json

@@ -70,5 +70,5 @@
     "forceConsistentCasingInFileNames": true        /* Disallow inconsistently-cased references to the same file. */
   },
   "include": ["src/**/*"],
-  "exclude": ["node_modules"],
+  "exclude": ["src/**/*.test.ts"]
 }

packages/watcher/package.json

@@ -22,6 +22,7 @@
     "@types/lodash": "^4.14.168",
     "@vulcanize/cache": "^0.1.0",
     "@vulcanize/ipld-eth-client": "^0.1.0",
+    "@vulcanize/solidity-mapper": "^0.1.0",
     "apollo-type-bigint": "^0.1.3",
     "canonical-json": "^0.0.4",
     "debug": "^4.3.1",

packages/watcher/src/artifacts/ERC20.json

@@ -0,0 +1,365 @@
+{
+  "abi": [
+    {
+      "inputs": [
+        {
+          "internalType": "string",
+          "name": "name_",
+          "type": "string"
+        },
+        {
+          "internalType": "string",
+          "name": "symbol_",
+          "type": "string"
+        }
+      ],
+      "stateMutability": "nonpayable",
+      "type": "constructor"
+    },
+    {
+      "anonymous": false,
+      "inputs": [
+        {
+          "indexed": true,
+          "internalType": "address",
+          "name": "owner",
+          "type": "address"
+        },
+        {
+          "indexed": true,
+          "internalType": "address",
+          "name": "spender",
+          "type": "address"
+        },
+        {
+          "indexed": false,
+          "internalType": "uint256",
+          "name": "value",
+          "type": "uint256"
+        }
+      ],
+      "name": "Approval",
+      "type": "event"
+    },
+    {
+      "anonymous": false,
+      "inputs": [
+        {
+          "indexed": true,
+          "internalType": "address",
+          "name": "from",
+          "type": "address"
+        },
+        {
+          "indexed": true,
+          "internalType": "address",
+          "name": "to",
+          "type": "address"
+        },
+        {
+          "indexed": false,
+          "internalType": "uint256",
+          "name": "value",
+          "type": "uint256"
+        }
+      ],
+      "name": "Transfer",
+      "type": "event"
+    },
+    {
+      "inputs": [
+        {
+          "internalType": "address",
+          "name": "owner",
+          "type": "address"
+        },
+        {
+          "internalType": "address",
+          "name": "spender",
+          "type": "address"
+        }
+      ],
+      "name": "allowance",
+      "outputs": [
+        {
+          "internalType": "uint256",
+          "name": "",
+          "type": "uint256"
+        }
+      ],
+      "stateMutability": "view",
+      "type": "function"
+    },
+    {
+      "inputs": [
+        {
+          "internalType": "address",
+          "name": "spender",
+          "type": "address"
+        },
+        {
+          "internalType": "uint256",
+          "name": "amount",
+          "type": "uint256"
+        }
+      ],
+      "name": "approve",
+      "outputs": [
+        {
+          "internalType": "bool",
+          "name": "",
+          "type": "bool"
+        }
+      ],
+      "stateMutability": "nonpayable",
+      "type": "function"
+    },
+    {
+      "inputs": [
+        {
+          "internalType": "address",
+          "name": "account",
+          "type": "address"
+        }
+      ],
+      "name": "balanceOf",
+      "outputs": [
+        {
+          "internalType": "uint256",
+          "name": "",
+          "type": "uint256"
+        }
+      ],
+      "stateMutability": "view",
+      "type": "function"
+    },
+    {
+      "inputs": [],
+      "name": "decimals",
+      "outputs": [
+        {
+          "internalType": "uint8",
+          "name": "",
+          "type": "uint8"
+        }
+      ],
+      "stateMutability": "view",
+      "type": "function"
+    },
+    {
+      "inputs": [
+        {
+          "internalType": "address",
+          "name": "spender",
+          "type": "address"
+        },
+        {
+          "internalType": "uint256",
+          "name": "subtractedValue",
+          "type": "uint256"
+        }
+      ],
+      "name": "decreaseAllowance",
+      "outputs": [
+        {
+          "internalType": "bool",
+          "name": "",
+          "type": "bool"
+        }
+      ],
+      "stateMutability": "nonpayable",
+      "type": "function"
+    },
+    {
+      "inputs": [
+        {
+          "internalType": "address",
+          "name": "spender",
+          "type": "address"
+        },
+        {
+          "internalType": "uint256",
+          "name": "addedValue",
+          "type": "uint256"
+        }
+      ],
+      "name": "increaseAllowance",
+      "outputs": [
+        {
+          "internalType": "bool",
+          "name": "",
+          "type": "bool"
+        }
+      ],
+      "stateMutability": "nonpayable",
+      "type": "function"
+    },
+    {
+      "inputs": [],
+      "name": "name",
+      "outputs": [
+        {
+          "internalType": "string",
+          "name": "",
+          "type": "string"
+        }
+      ],
+      "stateMutability": "view",
+      "type": "function"
+    },
+    {
+      "inputs": [],
+      "name": "symbol",
+      "outputs": [
+        {
+          "internalType": "string",
+          "name": "",
+          "type": "string"
+        }
+      ],
+      "stateMutability": "view",
+      "type": "function"
+    },
+    {
+      "inputs": [],
+      "name": "totalSupply",
+      "outputs": [
+        {
+          "internalType": "uint256",
+          "name": "",
+          "type": "uint256"
+        }
+      ],
+      "stateMutability": "view",
+      "type": "function"
+    },
+    {
+      "inputs": [
+        {
+          "internalType": "address",
+          "name": "recipient",
+          "type": "address"
+        },
+        {
+          "internalType": "uint256",
+          "name": "amount",
+          "type": "uint256"
+        }
+      ],
+      "name": "transfer",
+      "outputs": [
+        {
+          "internalType": "bool",
+          "name": "",
+          "type": "bool"
+        }
+      ],
+      "stateMutability": "nonpayable",
+      "type": "function"
+    },
+    {
+      "inputs": [
+        {
+          "internalType": "address",
+          "name": "sender",
+          "type": "address"
+        },
+        {
+          "internalType": "address",
+          "name": "recipient",
+          "type": "address"
+        },
+        {
+          "internalType": "uint256",
+          "name": "amount",
+          "type": "uint256"
+        }
+      ],
+      "name": "transferFrom",
+      "outputs": [
+        {
+          "internalType": "bool",
+          "name": "",
+          "type": "bool"
+        }
+      ],
+      "stateMutability": "nonpayable",
+      "type": "function"
+    }
+  ],
+  "storageLayout": {
+    "storage": [
+      {
+        "astId": 15,
+        "contract": "@openzeppelin/contracts/token/ERC20/ERC20.sol:ERC20",
+        "label": "_balances",
+        "offset": 0,
+        "slot": "0",
+        "type": "t_mapping(t_address,t_uint256)"
+      },
+      {
+        "astId": 21,
+        "contract": "@openzeppelin/contracts/token/ERC20/ERC20.sol:ERC20",
+        "label": "_allowances",
+        "offset": 0,
+        "slot": "1",
+        "type": "t_mapping(t_address,t_mapping(t_address,t_uint256))"
+      },
+      {
+        "astId": 23,
+        "contract": "@openzeppelin/contracts/token/ERC20/ERC20.sol:ERC20",
+        "label": "_totalSupply",
+        "offset": 0,
+        "slot": "2",
+        "type": "t_uint256"
+      },
+      {
+        "astId": 25,
+        "contract": "@openzeppelin/contracts/token/ERC20/ERC20.sol:ERC20",
+        "label": "_name",
+        "offset": 0,
+        "slot": "3",
+        "type": "t_string_storage"
+      },
+      {
+        "astId": 27,
+        "contract": "@openzeppelin/contracts/token/ERC20/ERC20.sol:ERC20",
+        "label": "_symbol",
+        "offset": 0,
+        "slot": "4",
+        "type": "t_string_storage"
+      }
+    ],
+    "types": {
+      "t_address": {
+        "encoding": "inplace",
+        "label": "address",
+        "numberOfBytes": "20"
+      },
+      "t_mapping(t_address,t_mapping(t_address,t_uint256))": {
+        "encoding": "mapping",
+        "key": "t_address",
+        "label": "mapping(address => mapping(address => uint256))",
+        "numberOfBytes": "32",
+        "value": "t_mapping(t_address,t_uint256)"
+      },
+      "t_mapping(t_address,t_uint256)": {
+        "encoding": "mapping",
+        "key": "t_address",
+        "label": "mapping(address => uint256)",
+        "numberOfBytes": "32",
+        "value": "t_uint256"
+      },
+      "t_string_storage": {
+        "encoding": "bytes",
+        "label": "string",
+        "numberOfBytes": "32"
+      },
+      "t_uint256": {
+        "encoding": "inplace",
+        "label": "uint256",
+        "numberOfBytes": "32"
+      }
+    }
+  }
+}

packages/watcher/src/resolvers.ts

@@ -4,11 +4,9 @@ import debug from 'debug';
 
 import { getCache } from '@vulcanize/cache';
 import { EthClient, getMappingSlot, topictoAddress } from '@vulcanize/ipld-eth-client';
+import { getStorageInfo } from '@vulcanize/solidity-mapper';
 
-// Event slots.
+import { storageLayout } from './artifacts/ERC20.json';
-// TODO: Read from storage layout file.
-const ERC20_BALANCE_OF_SLOT = "0x00";
-const ERC20_ALLOWANCE_SLOT = "0x01";
 
 // Event signatures.
 // TODO: Generate from ABI.
@@ -55,7 +53,8 @@ export const createResolvers = async (config) => {
       balanceOf: async (_, { blockHash, token, owner }) => {
         log('balanceOf', blockHash, token, owner);
 
-        const slot = getMappingSlot(ERC20_BALANCE_OF_SLOT, owner);
+        const { slot: balancesSlot } = getStorageInfo(storageLayout, '_balances')
+        const slot = getMappingSlot(balancesSlot, owner);
 
         const vars = {
           blockHash,
@@ -89,7 +88,8 @@ export const createResolvers = async (config) => {
       allowance: async (_, { blockHash, token, owner, spender }) => {
         log('allowance', blockHash, token, owner, spender);
 
-        const slot = getMappingSlot(getMappingSlot(ERC20_ALLOWANCE_SLOT, owner), spender);
+        const { slot: allowancesSlot } = getStorageInfo(storageLayout, '_allowances')
+        const slot = getMappingSlot(getMappingSlot(allowancesSlot, owner), spender);
 
         const vars = {
           blockHash,

tsconfig.json

@@ -66,6 +66,7 @@
 
     /* Advanced Options */
     "skipLibCheck": true,                           /* Skip type checking of declaration files. */
-    "forceConsistentCasingInFileNames": true        /* Disallow inconsistently-cased references to the same file. */
+    "forceConsistentCasingInFileNames": true,       /* Disallow inconsistently-cased references to the same file. */
+    "resolveJsonModule": true                       /* Enabling the option allows importing JSON, and validating the types in that JSON file. */
   }
 }