corrupt-something/index.js

Let's corrupt some datas

const fs = require('fs')
const minimist = require('minimist')
const getRandomIntInclusive = (min, max) => {
  return Math.floor(Math.random() * (max - min + 1)) + min
}
module.exports = () => {
  const args = minimist(process.argv.slice(2))
  let fileBuffer = fs.readFileSync(args['_'][0])
  let offset
  let end
  let bit
  if (typeof args.offset !== 'undefined') {
    offset = args.offset
  } else {
    offset = getRandomIntInclusive(0, fileBuffer.length)
  }
  if (typeof args.end !== 'undefined') {
    if (args.end === 'end') {
      end = fileBuffer.length - 3
    } else {
      end = args.end
    }
  } else {
    end = getRandomIntInclusive(0, fileBuffer.length)
  }
  if (typeof args.subEnd !== 'undefined') {
    end = fileBuffer.length - args.subEnd
  }
  if (typeof args.bit !== 'undefined') {
    bit = args.bit
    if (bit > 8) {
      throw new Error('Bit that over 8 is not allowed')
    }
  } else {
    bit = getRandomIntInclusive(0, 8)
  }

  if (offset > end) {
    let _ = parseInt(end)
    let __ = parseInt(offset)
    offset = _
    end = __
  }
  let position = offset
  while (end > position) {
    let a = fileBuffer.readInt32BE(position)
    fileBuffer.writeInt32BE(a | bit, position)
    position++
  }
  fs.writeFileSync(args['_'][0], fileBuffer)
}