eth-scripts

Some scripts for working with Ethereum et al.

Why

A place to collect notes gathered while studying the virtual machine and storage systems.

How

Each script (or javascript module) can generally be used standalone. Some are only useful in javascript programs, others are also useful in a browser / dapp context.

Dependencies

Some of the js modules depend on the ethers js library.

Downloading geth

download-geth 1.10.17 > geth
chmod +x bin/geth

Downloading solc

download-solc 0.8.13 > solc
chmod +x solc

Spawning a node

Spawns geth in dev mode with sane defaults suitable for testing and experimentation.

import geth from 'eth-scripts/geth.js'

const gethChildProcess = await geth('path/to/geth', {
  datadir: 'path/to/data',
  port: '3000',
  gasLimit: 11500000,
  gasCap: 0
})

Solidity compilation

Pass in a path to a solc executable and a standard-input-json like object, get back compiler output json as an object.

import compile from 'eth-scripts/compile.js'

const compilerOutput = await compile('path/to/solc', {
  sources: {
    'MyContract.sol': {
      urls: ['MyContract.sol']
    }
  }
})

Deploying compiled contracts

Pass in a signer and a javascript object map of contract "templates".

import { ethers } from 'ethers'
import deploy from 'eth-scripts/deploy.js'

const provider = new ethers.providers.JsonRpcProvider('http://localhost:3000')
const providerAccounts = await provider.listAccounts()
const signer = await provider.getSigner(providerAccounts[0])
const templates = {
  MyContract: {
    build: compilerOutput.contracts['MyContract.sol'].MyContract,
    args: [ 'some', 'constructor', 'args' ],
    preDeploy: (currentTemplate, allTemplates) => {},
    postDeploy: (currentTemplate, allTemplates) => {}
  }
}
await deploy(ethers, signer, templates)
const metadata = JSON.parse(templates.MyContract.metadata)
const ethersContract = templates.MyContract.contract
console.log(metadata.compiler.version)
console.log(metadata.settings.compilationTarget)
console.log(ethersContract.functions)

Watch a transaction until it has been mined

Awaits an ethers.js transaction and attempts to handle errors during its lifecycle in a consistent fashion whether they are generated by the rpc client, an eth node, or an on chain reversion. If the transcation was mined but also reverted, getRevertReason is invoked internally to synthesize the reason.

import watchTx from 'eth-scripts/watch-tx.js'

try {
  const tx = templates.MyContract.contract.someMethodThatModifiesState()
  await watchTx(provider, tx)
  console.log('transaction successful')
} catch (err) {
  console.log('transaction failed', err)
}

Getting the reason a transaction was reverted

If a transaction was reverted, this module can simulate the execution failure using eth_call to synthesize the reason. Attempts to normalize confusing and inconsistent ethers.js behavior.

import getRevertReason from 'eth-scripts/get-revert-reason.js'

const tx = templates.MyContract.contract.someMethodThatModifiesState()
await tx // assume transaction is sent and mined but reverts on chain
const reason = getRevertReason(provider, tx)

Decoding ABIEncoderV2 structs (and BigNumber) in a human friendly way

import abiv2 from 'eth-scripts/abiv2.js'

const someData = await contract.somePublicViewMethodThatReturnsStruct()
console.log(someData) /*
[
  BigNumber { _hex: '0x2a', _isBigNumber: true },
  BigNumber { _hex: '0x029a', _isBigNumber: true },
  BigNumber { _hex: '0x0539', _isBigNumber: true },
  x: BigNumber { _hex: '0x2a', _isBigNumber: true },
  y: BigNumber { _hex: '0x029a', _isBigNumber: true },
  z: BigNumber { _hex: '0x0539', _isBigNumber: true }
]
*/
const shouldConvertBigNumberToNumber = true
console.log(abiv2(someData, shouldConvertBigNumberToNumber)) // { x: 42, y: 666, z: 1337 }

Encoding constructor arguments

Useful for verifying contracts on Etherscan.

import encodeConstructorArgs from 'eth-scripts/encode-constructor-args.js'

const abi = compilerOutput.contracts['MyContract.sol'].MyContract.abi
const encodedArgs = encodeConstructorArgs(ethers, abi, [ 'some', 'constructor', 'args' ])

Generating standard-input-json

Given a sources map like the one output by the compiler, generates standard-input-json with sources content loaded from the filesystem. Useful for verifying contracts on Etherscan.

import generateStandardInputJson from 'eth-scripts/generate-standard-input-json.js'

const solcSettings = compile.defaultSettings
const standardInputJson = generateStandardInputJson(solcSettings, {
  "path/to/MyContract.sol": {
    "id": 0
  }
})
console.log(standardInputJason.sources)

Verifying contracts on Etherscan

Contract verification via Etherscan GUI doesn't always work.

import verify from 'eth-scripts/verify-etherscan.js'

const settings = compile.defaultSettings
const build = compile(/**/)
const templates = deploy(/**/)
const main = templates.MyContract
const metadata = JSON.parse(main.build.metadata)
const fileName = Object.keys(metadata.settings.compilationTarget)[0]
const contractName = metadata.settings.compilationTarget[file]
const res = await verify({
  network: 'rinkeby',
  fileName,
  contractName,
  address: main.address,
  sourceCode: JSON.stringify(await generateStandardInputJson(settings, build.sources)),
  constructorArgs: encodeConstructorArgs(ethers, main.abi, main.args),
  compilerVersion: metadata.compiler.version,
  licenseType: '3', // see https://etherscan.io/contract-license-types
  apiKey: 'XYZ' // see https://docs.etherscan.io/getting-started
})

License

MIT