const lodashOnce = require('lodash.once') 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 = lodashOnce(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('failed to kill process after timeout', { 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 }) }) }) }