shell: make shell.sudo promise based and waitable

src/shell.js

@@ -5,7 +5,8 @@ const assert = require('assert'),
     child_process = require('child_process'),
     debug = require('debug')('box:shell'),
     once = require('./once.js'),
-    util = require('util');
+    path = require('path'),
+    _ = require('./underscore.js');
 
 exports = module.exports = shell;
 
@@ -16,11 +17,12 @@ function shell(tag) {
         bash: bash.bind(null, tag),
         spawn: spawn.bind(null, tag),
         sudo: sudo.bind(null, tag),
-        promises: { sudo: util.promisify(sudo.bind(null, tag)) }
+        sudoCallback: sudoCallback.bind(null, tag)
     };
 }
 
 const SUDO = '/usr/bin/sudo';
+const KILL_CHILD_CMD = path.join(__dirname, 'scripts/kill-child.sh');
 
 function lineCount(buffer) {
     assert(Buffer.isBuffer(buffer));
@@ -44,18 +46,23 @@ function spawn(tag, file, args, options) {
     debug(`${tag}: ${file} ${args.join(' ').replace(/\n/g, '\\n')}`);
 
     const maxLines = options.maxLines || Number.MAX_SAFE_INTEGER;
+    const logger = options.logger || null;
+    const signal = options.signal || null; // note: we use our own handler and not the child_process one
 
     return new Promise((resolve, reject) => {
-        const cp = child_process.spawn(file, args, options);
+        const spawnOptions = _.omit(options, [ 'maxLines', 'logger', 'signal', 'onMessage', 'input', 'encoding' ]);
+        const cp = child_process.spawn(file, args, spawnOptions);
         const stdoutBuffers = [], stderrBuffers = [];
         let stdoutLineCount = 0, stderrLineCount = 0;
 
         cp.stdout.on('data', (data) => {
+            if (logger) return logger(data);
             stdoutBuffers.push(data);
             stdoutLineCount += lineCount(data);
             if (stdoutLineCount >= maxLines) return cp.kill('SIGKILL');
         });
         cp.stderr.on('data', (data) => {
+            if (logger) return logger(data);
             stderrBuffers.push(data);
             stderrLineCount += lineCount(data);
             if (stderrLineCount >= maxLines) return cp.kill('SIGKILL');
@@ -86,8 +93,16 @@ function spawn(tag, file, args, options) {
             debug(`${tag}: ${file} ${args.join(' ').replace(/\n/g, '\\n')} errored`, error);
         });
 
+        signal?.addEventListener('abort', () => {
+            child_process.execFile('/usr/bin/sudo', [ KILL_CHILD_CMD, cp.pid, process.pid ], { encoding: 'utf8' }, (error, stdout, stderr) => {
+                if (error) debug(`${tag}: failed to kill children`, stdout, stderr);
+            });
+        }, { once: true });
+
+        if (options.onMessage) cp.on('message', options.onMessage); // ipc mode messages
+
         // https://github.com/nodejs/node/issues/25231
-        if (options.input) {
+        if ('input' in options) { // when empty, just closes
             cp.stdin.write(options.input);
             cp.stdin.end();
         }
@@ -102,7 +117,25 @@ async function bash(tag, script, options) {
     return await spawn(tag, '/bin/bash', [ '-c', script ], options);
 }
 
-function sudo(tag, args, options, callback) {
+async function sudo(tag, args, options) {
+    assert.strictEqual(typeof tag, 'string');
+    assert(Array.isArray(args));
+    assert.strictEqual(typeof options, 'object');
+
+    const sudoArgs = [];
+    if (options.preserveEnv) sudoArgs.push('-E'); // -E preserves environment
+
+    if (options.onMessage) { // enable ipc
+         sudoArgs.push('--close-from=4'); // keep the ipc open. requires closefrom_override in sudoers file
+         options.stdio = ['pipe', 'pipe', 'pipe', 'ipc'];
+    }
+
+    const spawnArgs = [ ...sudoArgs, ...args ];
+
+    return await spawn(tag, SUDO, spawnArgs, options);
+}
+
+function sudoCallback(tag, args, options, callback) {
     assert.strictEqual(typeof tag, 'string');
     assert(Array.isArray(args));
     assert.strictEqual(typeof options, 'object');