electron/script/gn-asar.js

const asar = require('asar')
const assert = require('assert')
const fs = require('fs-extra')
const os = require('os')
const path = require('path')

const getArgGroup = (name) => {
  const group = []
  let inGroup = false
  for (const arg of process.argv) {
    // At the next flag we stop being in the current group
    if (arg.startsWith('--')) inGroup = false
    // Push all args in the group
    if (inGroup) group.push(arg)
    // If we find the start flag, start pushing
    if (arg === `--${name}`) inGroup = true
  }

  return group
}

const base = getArgGroup('base')
const files = getArgGroup('files')
const out = getArgGroup('out')

assert(base.length === 1, 'should have a single base dir')
assert(files.length >= 1, 'should have at least one input file')
assert(out.length === 1, 'should have a single out path')

// Ensure all files are inside the base dir
for (const file of files) {
  if (!file.startsWith(base[0])) {
    console.error(`Expected all files to be inside the base dir but "${file}" was not in "${base[0]}"`)
    process.exit(1)
  }
}

const tmpPath = fs.mkdtempSync(path.resolve(os.tmpdir(), 'electron-gn-asar-'))

try {
  // Copy all files to a tmp dir to avoid including scrap files in the ASAR
  for (const file of files) {
    const newLocation = path.resolve(tmpPath, path.relative(base[0], file))
    fs.mkdirsSync(path.dirname(newLocation))
    fs.writeFileSync(newLocation, fs.readFileSync(file))
  }
} catch (err) {
  console.error('Unexpected error while generating ASAR', err)
  fs.remove(tmpPath)
    .then(() => process.exit(1))
    .catch(() => process.exit(1))
  return
}

// Create the ASAR archive
asar.createPackageWithOptions(tmpPath, out[0], {})
  .catch(err => {
    const exit = () => {
      console.error('Unexpected error while generating ASAR', err)
      process.exit(1)
    }
    fs.remove(tmpPath).then(exit).catch(exit)
  }).then(() => fs.remove(tmpPath))