Strange behavior of node js spawn/exec with unzipped content

Question

I'm trying to write a client which installs and updates packages using nodejs with mqtt. I tested all functionalities of data transfer and archiving but when I came to windows environment and actualy tried to run some scripts I came to some strange errors.

I will add some code so anyone can see exacly how I write downloaded content to disk but first I will explain behaviour.

Steps taken for each itteration:

download content from mqtt (works)
create buffer and stream from it (works)
unzip stream to disk (works)
run batch job in downloaded content (strange things happen)
run another batch job (even stranger)

Strange things: At first try spawn/exec respoonses with: error spawn cmd.exe ENOENT, but at second try (triggered by topic subscription) it goes over that stage. But the next itteration when first batch job passes second job returns Error: EBUSY: resource busy or locked, open C:\...appt@0.0.1\nssm.exe' where nssm.exe is file called from batch job

Code for downloading and extraction:

const debug = require('debug')('service-manager:functions:download')
const serviceBus = require('../helpers/mqtt-helper.js')
const stream = require('stream')
const unzip = require('unzip-stream')

module.exports = (service, to, from) => {
  debug(`Downloading ${service}@${to}`)
  return serviceBus.getFromBus(`service_manager/${service}/${to}`)
    .then(data => {
      debug(`Downloaded ${service}@${to}`)
      return new Promise((resolve, reject) => {
        debug(`Unzipping ${service}@${to}`)
        const buffer = Buffer.from(data)
        const bufferStream = new stream.PassThrough()
        bufferStream.end(buffer)
        bufferStream.pipe(unzip.Extract({
          path: `${__dirname}/../../services/active/${service}@${to}`
        })).on('finish', resolve)
      }).then(() => {
        debug(`Unzipped ${service}@${to}`)
      })
    })
}

Code used to run batch jobs:

const debug = require('debug')('service-manager:functions:runner')
const { exec } = require('child_process')
const { resolve } = require('path')
module.exports = (type, reverse) => (service, to, from) => {
  return new Promise((resolve, reject) => {
    debug(`Running ${type} for ${service}@${reverse ? from : to}`)
    const batchFile = resolve(
      `../../services/active/${service}@${reverse ? from : to}/${type}.sh`
    )
    exec(batchFile, (error, stdout, stderr) => {
      if (error) {
        return reject(error)
      }
      debug(`Gotten STDOUT on ${type} for ${service}@${reverse ? from : to}: ${stdout}`)
      debug(`Gotten STDERR on ${type} for ${service}@${reverse ? from : to}: ${stderr}`)
      return resolve()
    })
  })
}

score 0 · Accepted Answer · answered Sep 03 '17 at 09:23

0

It turns out that unzip-stream called finish and close event before files were written on dist which resulted in files not being accessible to run with batch script. I swaped libraries and it worked.

answered Sep 03 '17 at 09:23

klemen676

13
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Strange behavior of node js spawn/exec with unzipped content

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