cloudron-box/src/shell.js

'use strict';

const assert = require('assert'),
    BoxError = require('./boxerror.js'),
    child_process = require('child_process'),
    debug = require('debug')('box:shell'),
    once = require('./once.js'),
    util = require('util');

exports = module.exports = {
    exec,
    execArgs,

    sudo,

    promises: {
        sudo: util.promisify(sudo)
    }
};

const SUDO = '/usr/bin/sudo';

// default encoding utf8, no shell, separate args, wait for process to finish
async function execArgs(tag, file, args, options) {
    assert.strictEqual(typeof tag, 'string');
    assert.strictEqual(typeof file, 'string');
    assert(Array.isArray(args));
    assert.strictEqual(typeof options, 'object');

    debug(`${tag} execArgs: ${file} ${JSON.stringify(args)}`);

    const execOptions = Object.assign({ encoding: 'utf8', shell: false }, options);

    return new Promise((resolve, reject) => {
        const cp = child_process.execFile(file, args, execOptions, function (error, stdout, stderr) {
            if (!error) return resolve(stdout);

            const e = new BoxError(BoxError.SHELL_ERROR, `${tag} errored with code ${error.code} message ${error.message}`);
            e.stdout = stdout; // when promisified, this is the way to get stdout
            e.stderr = stderr; // when promisified, this is the way to get stderr
            debug(`${tag}: ${file} with args ${args.join(' ')} errored`, error);
            reject(e);
        });

        // https://github.com/nodejs/node/issues/25231
        if (options.input) {
            cp.stdin.write(options.input);
            cp.stdin.end();
        }
    });
}

// default encoding utf8, no shell, handles input, full command, wait for process to finish
async function exec(tag, cmd, options) {
    assert.strictEqual(typeof tag, 'string');
    assert.strictEqual(typeof cmd, 'string');
    assert.strictEqual(typeof options, 'object');

    if (!options.shell) {
        cmd = cmd.replace(/\s+/g, ' '); // collapse spaces when not using shell. note: no more complexity like parsing quotes here!
        const [file, ...args] = cmd.split(' ');
        return await execArgs(tag, file, args, options);
    }

    debug(`${tag} exec: ${cmd}`);

    return new Promise((resolve, reject) => {
        const cp = child_process.exec(cmd, options, function (error, stdout, stderr) {
            if (!error) return resolve(stdout);

            const e = new BoxError(BoxError.SHELL_ERROR, `${tag} errored with code ${error.code} message ${error.message}`);
            e.stdout = stdout; // when promisified, this is the way to get stdout
            e.stderr = stderr; // when promisified, this is the way to get stderr
            debug(`${tag}: ${cmd} errored`, error);
            reject(e);
        });

        // https://github.com/nodejs/node/issues/25231
        if (options.input) {
            cp.stdin.write(options.input);
            cp.stdin.end();
        }
    });
}

function sudo(tag, args, options, callback) {
    assert.strictEqual(typeof tag, 'string');
    assert(Array.isArray(args));
    assert.strictEqual(typeof options, 'object');
    assert.strictEqual(typeof callback, 'function');

    const sudoArgs = [ '-S' ]; // -S makes sudo read stdin for password
    if (options.preserveEnv) sudoArgs.push('-E'); // -E preserves environment
    if (options.ipc) sudoArgs.push('--close-from=4'); // keep the ipc open. requires closefrom_override in sudoers file

    callback = once(callback); // exit may or may not be called after an 'error'

    if (options.ipc) options.stdio = ['pipe', 'pipe', 'pipe', 'ipc'];

    const spawnArgs = sudoArgs.concat(args);

    debug(`${tag} ${SUDO} ${spawnArgs.join(' ').replace(/\n/g, '\\n')}`);
    const cp = child_process.spawn(SUDO, spawnArgs, options);
    let stdoutResult = '';

    if (!options.streamStdout) cp.stdout.on('data', (data) => stdoutResult += data.toString('utf8'));

    cp.on('exit', function (code, signal) {
        if (code === 0) return callback(null, options.streamStdout ? null : stdoutResult);
        const e = new BoxError(BoxError.SHELL_ERROR, `${tag} exited with code ${code} signal ${signal}`);
        e.code = code;
        e.signal = signal;

        if (cp.terminated) {
            debug(`${tag}: ${SUDO} ${spawnArgs.join(' ').replace(/\n/g, '\\n')} terminated`); // was killed by us
        } else {
            debug(`${tag}: ${SUDO} ${spawnArgs.join(' ').replace(/\n/g, '\\n')} errored`, e);
        }

        callback(e);
    });

    cp.on('error', function (error) {
        debug(`${tag}: ${SUDO} ${spawnArgs.join(' ').replace(/\n/g, '\\n')} errored`, error);
        const e = new BoxError(BoxError.SHELL_ERROR, `${tag} errored with code ${error.code} message ${error.message}`);
        callback(e);
    });

    // sudo forks and execs the program. sudo also hangs around as the parent of the program waiting on the program and also forwarding signals.
    // sudo does not forward signals when the originator comes from the same process group. recently, there has been a change where it will
    // forward signals as long as sudo or the command is not the group leader (https://www.sudo.ws/repos/sudo/rev/d1bf60eac57f)
    // for us, this means that calling kill from this node process doesn't work since it's in the same group (and ubuntu 22 doesn't have the above fix).
    // the workaround is to invoke a kill from a different process group and this is done by starting detached
    // another idea is: use "ps --pid cp.pid -o pid=" to get the pid of the command and then send it signal directly
    cp.terminate = function () {
        cp.terminated = true; // hint for better debug message in 'exit'
        child_process.spawn('kill', ['-SIGTERM', cp.pid], { detached: true }, (error) => { if (error) debug(`${tag} could not terminate`, error); });
    };

    cp.stdin.end();
    if (options.onMessage) cp.on('message', options.onMessage);

    return cp;
}