shell: no need to promise scoping

src/shell.js

@@ -8,11 +8,12 @@ const assert = require('assert'),
     util = require('util');
 
 exports = module.exports = {
+    exec,
+    execArgs,
+
     sudo,
 
     promises: {
-        exec: util.promisify(exec),
-        execArgs: util.promisify(execArgs),
         sudo: util.promisify(sudo)
     }
 };
@@ -20,46 +21,43 @@ exports = module.exports = {
 const SUDO = '/usr/bin/sudo';
 
 // default encoding utf8, no shell, separate args
-function execArgs(tag, file, args, options, callback) {
+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');
-    assert.strictEqual(typeof callback, 'function');
 
     debug(`${tag} exec: ${file}`);
 
     const execOptions = Object.assign({ encoding: 'utf8', shell: false }, options);
 
-    // https://github.com/nodejs/node/issues/25231
-    const cp = child_process.execFile(file, args, execOptions, function (error, stdout, stderr) {
-        let e = null;
-        if (error) {
-            e = new BoxError(BoxError.SHELL_ERROR, `${tag} errored with code ${error.code} message ${error.message}`);
+    return new Promise((resolve, reject) => {
+        const cp = child_process.execFile(file, args, execOptions, function (error, stdout, stderr) {
+            if (!error) return resolve(stdout);
+
+            const e = new BoxError(BoxError.SHELL_ERROR, `${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();
         }
-
-        callback(e, stdout);
     });
-
-    if (options.input) {
-        cp.stdin.write(options.input);
-        cp.stdin.end();
-    }
 }
 
 // default encoding utf8, shell, handles input, full command
-function exec(tag, cmd, options, callback) {
+async function exec(tag, cmd, options) {
     assert.strictEqual(typeof tag, 'string');
     assert.strictEqual(typeof cmd, 'string');
     assert.strictEqual(typeof options, 'object');
-    assert.strictEqual(typeof callback, 'function');
 
     const [file, ...args] = cmd.split(' ');
-    execArgs(tag, file, args, options, callback);
+    return await execArgs(tag, file, args, options);
 }
 
 // use this when you are afraid of how arguments will split up