overleaf/services/filestore/app/js/SafeExec.js
2020-01-10 15:41:36 +00:00

88 lines
2.1 KiB
JavaScript

const _ = require('underscore')
const childProcess = require('child_process')
const Settings = require('settings-sharelatex')
const { ConversionsDisabledError, FailedCommandError } = require('./Errors')
// execute a command in the same way as 'exec' but with a timeout that
// kills all child processes
//
// we spawn the command with 'detached:true' to make a new process
// group, then we can kill everything in that process group.
module.exports = safeExec
module.exports.promises = safeExecPromise
// options are {timeout: number-of-milliseconds, killSignal: signal-name}
function safeExec(command, options, callback) {
if (!Settings.enableConversions) {
return callback(
new ConversionsDisabledError('image conversions are disabled')
)
}
const [cmd, ...args] = command
const child = childProcess.spawn(cmd, args, { detached: true })
let stdout = ''
let stderr = ''
let killTimer
const cleanup = _.once(function(err) {
if (killTimer) {
clearTimeout(killTimer)
}
callback(err, stdout, stderr)
})
if (options.timeout) {
killTimer = setTimeout(function() {
try {
// use negative process id to kill process group
process.kill(-child.pid, options.killSignal || 'SIGTERM')
} catch (error) {
cleanup(
new FailedCommandError({
message: 'failed to kill process after timeout',
info: {
command,
options,
pid: child.pid
}
})
)
}
}, options.timeout)
}
child.on('close', function(code, signal) {
if (code || signal) {
return cleanup(
new FailedCommandError(command, code || signal, stdout, stderr)
)
}
cleanup()
})
child.on('error', err => {
cleanup(err)
})
child.stdout.on('data', chunk => {
stdout += chunk
})
child.stderr.on('data', chunk => {
stderr += chunk
})
}
function safeExecPromise(command, options) {
return new Promise((resolve, reject) => {
safeExec(command, options, (err, stdout, stderr) => {
if (err) {
reject(err)
}
resolve({ stdout, stderr })
})
})
}