hardhat-storage-layout

Generate Ethereum smart contract storage layout with Hardhat. This plugin saves time and avoids human error when a developer tries to update a specific storage slot in a remote solidity contract. For more info about the storage layout, please refer to the official solidity documentation.

Installation

yarn add --dev hardhat-storage-layout

Usage

• Add this plugin to hardhat.config.js:

require('hardhat-storage-layout');

• Compile your contracts (Solc version must be grather than 0.5.13)
• Run yarn hardhat check

Or

• Export the contracts storage layout prior deployment as follows:

const hre = require("hardhat");

async function main() {
....
  await
  hre.storageLayout.export();
}

┌─────────────────┬────────────────┬──────────────┬────────┬─────────────────────────────────────────────────────┬────────────────┐
│ contract        │ state_variable │ storage_slot │ offset │ type                                                │ numberOfBytes  │
├─────────────────┼────────────────┼──────────────┼────────┼─────────────────────────────────────────────────────┤────────────────┤
│ ERC20           │ _balances      │      0       │   0    │ t_mapping(t_address,t_uint256)                      │1               │
│ ERC20           │ _allowances    │      1       │   0    │ t_mapping(t_address,t_mapping(t_address,t_uint256)) │1               │
│ ERC20           │ _totalSupply   │      2       │   0    │ t_uint256                                           │1               │
│ ERC20           │ _name          │      3       │   0    │ t_string_storage                                    │1               │
│ ERC20           │ _symbol        │      4       │   0    │ t_string_storage                                    │1               │
│ WatermelonToken │ _balances      │      0       │   0    │ t_mapping(t_address,t_uint256)                      │1               │
│ WatermelonToken │ _allowances    │      1       │   0    │ t_mapping(t_address,t_mapping(t_address,t_uint256)) │1               │
│ WatermelonToken │ _totalSupply   │      2       │   0    │ t_uint256                                           │1               │
│ WatermelonToken │ _name          │      3       │   0    │ t_string_storage                                    │1               │
│ WatermelonToken │ _symbol        │      4       │   0    │ t_string_storage                                    │1               │
└─────────────────┴────────────────┴──────────────┴────────┴─────────────────────────────────────────────────────┘────────────────┘

• contract: is the name of the contract including its path as prefix
• state variable: is the name of the state variable
• offset: is the offset in bytes within the storage slot according to the encoding
• storage slot: is the storage slot where the state variable resides or starts. This number may be very large and therefore its JSON value is represented as a string.
• type: is an identifier used as key to the variable’s type information (described in the following)
• numberOfBytes: is the nummber of bytes used by the state variable.