child_process: attach child in promisification

This commit updates the custom exec() and execFile()
promisification to attach the ChildProcess instance to the
returned Promise.

PR-URL: https://github.com/nodejs/node/pull/28325
Fixes: https://github.com/nodejs/node/issues/28244
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Wyatt Preul <wpreul@gmail.com>

1 files changed, 17 insertions, 10 deletions

diff --git a/lib/child_process.js b/lib/child_process.js
index 66be7611dc..0d3785f0d5 100644
--- a/lib/child_process.js
+++ b/lib/child_process.js
@@ -149,17 +149,24 @@ function exec(command, options, callback) {
 
 const customPromiseExecFunction = (orig) => {
   return (...args) => {
-    return new Promise((resolve, reject) => {
-      orig(...args, (err, stdout, stderr) => {
-        if (err !== null) {
-          err.stdout = stdout;
-          err.stderr = stderr;
-          reject(err);
-        } else {
-          resolve({ stdout, stderr });
-        }
-      });
+    let resolve;
+    let reject;
+    const promise = new Promise((res, rej) => {
+      resolve = res;
+      reject = rej;
     });
+
+    promise.child = orig(...args, (err, stdout, stderr) => {
+      if (err !== null) {
+        err.stdout = stdout;
+        err.stderr = stderr;
+        reject(err);
+      } else {
+        resolve({ stdout, stderr });
+      }
+    });
+
+    return promise;
   };
 };