From 6bcafff5611f02ce470ce422f005498d6334ebe3 Mon Sep 17 00:00:00 2001
From: Benjamin Gruenbaum <benjamingr@gmail.com>
Date: Sat, 28 Nov 2020 21:42:34 +0200
Subject: [PATCH] child_process: add AbortSignal support

PR-URL: https://github.com/nodejs/node/pull/36308
Reviewed-By: Rich Trott <rtrott@gmail.com>
---
 doc/api/child_process.md                     | 17 +++++++++++
 lib/child_process.js                         | 32 ++++++++++++++++++--
 test/parallel/test-bootstrap-modules.js      |  1 +
 test/parallel/test-child-process-execfile.js | 15 +++++++++
 4 files changed, 62 insertions(+), 3 deletions(-)

diff --git a/doc/api/child_process.md b/doc/api/child_process.md
index 6f6c81e253ff06..1b9fc0229ab389 100644
--- a/doc/api/child_process.md
+++ b/doc/api/child_process.md
@@ -250,6 +250,9 @@ lsExample();
 <!-- YAML
 added: v0.1.91
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/36308
+    description: AbortSignal support was added.
   - version: v8.8.0
     pr-url: https://github.com/nodejs/node/pull/15380
     description: The `windowsHide` option is supported now.
@@ -277,6 +280,7 @@ changes:
     `'/bin/sh'` on Unix, and `process.env.ComSpec` on Windows. A different
     shell can be specified as a string. See [Shell requirements][] and
     [Default Windows shell][]. **Default:** `false` (no shell).
+  * `signal` {AbortSignal} allows aborting the execFile using an AbortSignal
 * `callback` {Function} Called with the output when process terminates.
   * `error` {Error}
   * `stdout` {string|Buffer}
@@ -330,6 +334,19 @@ getVersion();
 function. Any input containing shell metacharacters may be used to trigger
 arbitrary command execution.**
 
+If the `signal` option is enabled, calling `.abort()` on the corresponding
+`AbortController` is similar to calling `.kill()` on the child process except
+the error passed to the callback will be an `AbortError`:
+
+```js
+const controller = new AbortController();
+const { signal } = controller;
+const child = execFile('node', ['--version'], { signal }, (error) => {
+  console.log(error); // an AbortError
+});
+signal.abort();
+```
+
 ### `child_process.fork(modulePath[, args][, options])`
 <!-- YAML
 added: v0.5.0
diff --git a/lib/child_process.js b/lib/child_process.js
index 9e1c37af8f169f..1b645e43c8151b 100644
--- a/lib/child_process.js
+++ b/lib/child_process.js
@@ -45,15 +45,24 @@ let debug = require('internal/util/debuglog').debuglog(
 );
 const { Buffer } = require('buffer');
 const { Pipe, constants: PipeConstants } = internalBinding('pipe_wrap');
+
+const {
+  AbortError,
+  codes: errorCodes,
+} = require('internal/errors');
 const {
   ERR_INVALID_ARG_VALUE,
   ERR_CHILD_PROCESS_IPC_REQUIRED,
   ERR_CHILD_PROCESS_STDIO_MAXBUFFER,
   ERR_INVALID_ARG_TYPE,
-  ERR_OUT_OF_RANGE
-} = require('internal/errors').codes;
+  ERR_OUT_OF_RANGE,
+} = errorCodes;
 const { clearTimeout, setTimeout } = require('timers');
-const { validateString, isInt32 } = require('internal/validators');
+const {
+  validateString,
+  isInt32,
+  validateAbortSignal,
+} = require('internal/validators');
 const child_process = require('internal/child_process');
 const {
   getValidStdio,
@@ -232,6 +241,9 @@ function execFile(file /* , args, options, callback */) {
   // Validate maxBuffer, if present.
   validateMaxBuffer(options.maxBuffer);
 
+  // Validate signal, if present
+  validateAbortSignal(options.signal, 'options.signal');
+
   options.killSignal = sanitizeKillSignal(options.killSignal);
 
   const child = spawn(file, args, {
@@ -349,6 +361,20 @@ function execFile(file /* , args, options, callback */) {
       timeoutId = null;
     }, options.timeout);
   }
+  if (options.signal) {
+    if (options.signal.aborted) {
+      process.nextTick(() => kill());
+    } else {
+      options.signal.addEventListener('abort', () => {
+        if (!ex) {
+          ex = new AbortError();
+        }
+        kill();
+      });
+      const remove = () => options.signal.removeEventListener('abort', kill);
+      child.once('close', remove);
+    }
+  }
 
   if (child.stdout) {
     if (encoding)
diff --git a/test/parallel/test-bootstrap-modules.js b/test/parallel/test-bootstrap-modules.js
index c751e41dcca6da..3c920a5ab3edb3 100644
--- a/test/parallel/test-bootstrap-modules.js
+++ b/test/parallel/test-bootstrap-modules.js
@@ -96,6 +96,7 @@ if (!common.isMainThread) {
     'Internal Binding performance',
     'Internal Binding symbols',
     'Internal Binding worker',
+    'NativeModule internal/streams/add-abort-signal',
     'NativeModule internal/streams/duplex',
     'NativeModule internal/streams/passthrough',
     'NativeModule internal/streams/readable',
diff --git a/test/parallel/test-child-process-execfile.js b/test/parallel/test-child-process-execfile.js
index bc0495b3332384..389ad73c228762 100644
--- a/test/parallel/test-child-process-execfile.js
+++ b/test/parallel/test-child-process-execfile.js
@@ -1,3 +1,4 @@
+// Flags: --experimental-abortcontroller
 'use strict';
 
 const common = require('../common');
@@ -7,6 +8,7 @@ const { getSystemErrorName } = require('util');
 const fixtures = require('../common/fixtures');
 
 const fixture = fixtures.path('exit.js');
+const echoFixture = fixtures.path('echo.js');
 const execOpts = { encoding: 'utf8', shell: true };
 
 {
@@ -45,3 +47,16 @@ const execOpts = { encoding: 'utf8', shell: true };
   // Verify the shell option works properly
   execFile(process.execPath, [fixture, 0], execOpts, common.mustSucceed());
 }
+
+{
+  // Verify that the signal option works properly
+  const ac = new AbortController();
+  const { signal } = ac;
+
+  const callback = common.mustCall((err) => {
+    assert.strictEqual(err.code, 'ABORT_ERR');
+    assert.strictEqual(err.name, 'AbortError');
+  });
+  execFile(process.execPath, [echoFixture, 0], { signal }, callback);
+  ac.abort();
+}