From 08d8f2eb0f2031308ee8435a262b765a629cd73c Mon Sep 17 00:00:00 2001
From: Yagiz Nizipli <yagiz@nizipli.com>
Date: Mon, 31 Oct 2022 19:15:45 -0400
Subject: [PATCH] fs: add recursive watch to linux

PR-URL: https://github.com/nodejs/node/pull/45098
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
---
 doc/api/fs.md                                 |   7 +-
 lib/fs.js                                     |  26 +-
 lib/internal/fs/promises.js                   |  27 +-
 lib/internal/fs/recursive_watch.js            | 281 ++++++++++++++++++
 test/parallel/test-bootstrap-modules.js       |   1 +
 .../test-fs-watch-close-when-destroyed.js     |   7 +
 test/parallel/test-fs-watch-encoding.js       |   3 +
 test/parallel/test-fs-watch-enoent.js         |  44 +--
 .../test-fs-watch-recursive-promise.js        |  94 ++++++
 .../test-fs-watch-recursive-symlink.js        | 100 +++++++
 test/parallel/test-fs-watch-recursive.js      | 245 ++++++++++++---
 test/parallel/test-fs-watchfile.js            |   4 +-
 test/sequential/test-fs-watch.js              |  72 ++---
 13 files changed, 802 insertions(+), 109 deletions(-)
 create mode 100644 lib/internal/fs/recursive_watch.js
 create mode 100644 test/parallel/test-fs-watch-recursive-promise.js
 create mode 100644 test/parallel/test-fs-watch-recursive-symlink.js

diff --git a/doc/api/fs.md b/doc/api/fs.md
index c15d98073b24da..40ddd8fff1ea99 100644
--- a/doc/api/fs.md
+++ b/doc/api/fs.md
@@ -4301,6 +4301,9 @@ The `atime` and `mtime` arguments follow these rules:
 <!-- YAML
 added: v0.5.10
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/45098
+    description: Added recursive support for Linux, AIX and IBMi.
   - version:
       - v15.9.0
       - v14.17.0
@@ -4358,10 +4361,6 @@ the returned {fs.FSWatcher}.
 The `fs.watch` API is not 100% consistent across platforms, and is
 unavailable in some situations.
 
-The recursive option is only supported on macOS and Windows.
-An `ERR_FEATURE_UNAVAILABLE_ON_PLATFORM` exception will be thrown
-when the option is used on a platform that does not support it.
-
 On Windows, no events will be emitted if the watched directory is moved or
 renamed. An `EPERM` error is reported when the watched directory is deleted.
 
diff --git a/lib/fs.js b/lib/fs.js
index 83c797f2c8c941..7dea7dc14b2a0d 100644
--- a/lib/fs.js
+++ b/lib/fs.js
@@ -58,6 +58,7 @@ const {
 
 const pathModule = require('path');
 const { isArrayBufferView } = require('internal/util/types');
+const nonNativeWatcher = require('internal/fs/recursive_watch');
 
 // We need to get the statValues from the binding at the callsite since
 // it's re-initialized after deserialization.
@@ -69,7 +70,6 @@ const {
   codes: {
     ERR_FS_FILE_TOO_LARGE,
     ERR_INVALID_ARG_VALUE,
-    ERR_FEATURE_UNAVAILABLE_ON_PLATFORM,
   },
   AbortError,
   uvErrmapGet,
@@ -166,7 +166,6 @@ let FileWriteStream;
 const isWindows = process.platform === 'win32';
 const isOSX = process.platform === 'darwin';
 
-
 const showStringCoercionDeprecation = deprecate(
   () => {},
   'Implicit coercion of objects with own toString property is deprecated.',
@@ -2309,13 +2308,22 @@ function watch(filename, options, listener) {
 
   if (options.persistent === undefined) options.persistent = true;
   if (options.recursive === undefined) options.recursive = false;
-  if (options.recursive && !(isOSX || isWindows))
-    throw new ERR_FEATURE_UNAVAILABLE_ON_PLATFORM('watch recursively');
-  const watcher = new watchers.FSWatcher();
-  watcher[watchers.kFSWatchStart](filename,
-                                  options.persistent,
-                                  options.recursive,
-                                  options.encoding);
+
+  let watcher;
+
+  // TODO(anonrig): Remove this when/if libuv supports it.
+  // As of November 2022, libuv does not support recursive file watch on all platforms,
+  // e.g. Linux due to the limitations of inotify.
+  if (options.recursive && !isOSX && !isWindows) {
+    watcher = new nonNativeWatcher.FSWatcher(options);
+    watcher[watchers.kFSWatchStart](filename);
+  } else {
+    watcher = new watchers.FSWatcher();
+    watcher[watchers.kFSWatchStart](filename,
+                                    options.persistent,
+                                    options.recursive,
+                                    options.encoding);
+  }
 
   if (listener) {
     watcher.addListener('change', listener);
diff --git a/lib/internal/fs/promises.js b/lib/internal/fs/promises.js
index eca3dc8adfae3b..0e0241149701e9 100644
--- a/lib/internal/fs/promises.js
+++ b/lib/internal/fs/promises.js
@@ -87,7 +87,8 @@ const {
 } = require('internal/util');
 const { EventEmitterMixin } = require('internal/event_target');
 const { StringDecoder } = require('string_decoder');
-const { watch } = require('internal/fs/watchers');
+const { kFSWatchStart, watch } = require('internal/fs/watchers');
+const nonNativeWatcher = require('internal/fs/recursive_watch');
 const { isIterable } = require('internal/streams/utils');
 const assert = require('internal/assert');
 
@@ -118,6 +119,8 @@ const {
 const getDirectoryEntriesPromise = promisify(getDirents);
 const validateRmOptionsPromise = promisify(validateRmOptions);
 
+const isOSX = process.platform === 'darwin';
+
 let cpPromises;
 function lazyLoadCpPromises() {
   return cpPromises ??= require('internal/fs/cp/cp').cpFn;
@@ -902,6 +905,26 @@ async function readFile(path, options) {
   return handleFdClose(readFileHandle(fd, options), fd.close);
 }
 
+async function* _watch(filename, options = kEmptyObject) {
+  validateObject(options, 'options');
+
+  if (options.recursive != null) {
+    validateBoolean(options.recursive, 'options.recursive');
+
+    // TODO(anonrig): Remove this when/if libuv supports it.
+    // As of November 2022, libuv does not support recursive file watch on all platforms,
+    // e.g. Linux due to the limitations of inotify.
+    if (options.recursive && !isOSX && !isWindows) {
+      const watcher = new nonNativeWatcher.FSWatcher(options);
+      await watcher[kFSWatchStart](filename);
+      yield* watcher;
+      return;
+    }
+  }
+
+  yield* watch(filename, options);
+}
+
 module.exports = {
   exports: {
     access,
@@ -932,7 +955,7 @@ module.exports = {
     writeFile,
     appendFile,
     readFile,
-    watch,
+    watch: !isOSX && !isWindows ? _watch : watch,
     constants,
   },
 
diff --git a/lib/internal/fs/recursive_watch.js b/lib/internal/fs/recursive_watch.js
new file mode 100644
index 00000000000000..197c4f1a461724
--- /dev/null
+++ b/lib/internal/fs/recursive_watch.js
@@ -0,0 +1,281 @@
+'use strict';
+
+const {
+  ArrayPrototypePush,
+  SafePromiseAllReturnVoid,
+  Promise,
+  PromisePrototypeThen,
+  SafeMap,
+  SafeSet,
+  StringPrototypeStartsWith,
+  SymbolAsyncIterator,
+} = primordials;
+
+const { EventEmitter } = require('events');
+const assert = require('internal/assert');
+const {
+  AbortError,
+  codes: {
+    ERR_INVALID_ARG_VALUE,
+  },
+} = require('internal/errors');
+const { getValidatedPath } = require('internal/fs/utils');
+const { kFSWatchStart, StatWatcher } = require('internal/fs/watchers');
+const { kEmptyObject } = require('internal/util');
+const { validateBoolean, validateAbortSignal } = require('internal/validators');
+const path = require('path');
+
+let internalSync;
+let internalPromises;
+
+function lazyLoadFsPromises() {
+  internalPromises ??= require('fs/promises');
+  return internalPromises;
+}
+
+function lazyLoadFsSync() {
+  internalSync ??= require('fs');
+  return internalSync;
+}
+
+async function traverse(dir, files = new SafeMap(), symbolicLinks = new SafeSet()) {
+  const { opendir } = lazyLoadFsPromises();
+
+  const filenames = await opendir(dir);
+  const subdirectories = [];
+
+  for await (const file of filenames) {
+    const f = path.join(dir, file.name);
+
+    files.set(f, file);
+
+    // Do not follow symbolic links
+    if (file.isSymbolicLink()) {
+      symbolicLinks.add(f);
+    } else if (file.isDirectory()) {
+      ArrayPrototypePush(subdirectories, traverse(f, files));
+    }
+  }
+
+  await SafePromiseAllReturnVoid(subdirectories);
+
+  return files;
+}
+
+class FSWatcher extends EventEmitter {
+  #options = null;
+  #closed = false;
+  #files = new SafeMap();
+  #symbolicFiles = new SafeSet();
+  #rootPath = path.resolve();
+  #watchingFile = false;
+
+  constructor(options = kEmptyObject) {
+    super();
+
+    assert(typeof options === 'object');
+
+    const { persistent, recursive, signal, encoding } = options;
+
+    // TODO(anonrig): Add non-recursive support to non-native-watcher for IBMi & AIX support.
+    if (recursive != null) {
+      validateBoolean(recursive, 'options.recursive');
+    }
+
+    if (persistent != null) {
+      validateBoolean(persistent, 'options.persistent');
+    }
+
+    if (signal != null) {
+      validateAbortSignal(signal, 'options.signal');
+    }
+
+    if (encoding != null) {
+      // This is required since on macOS and Windows it throws ERR_INVALID_ARG_VALUE
+      if (typeof encoding !== 'string') {
+        throw new ERR_INVALID_ARG_VALUE(encoding, 'options.encoding');
+      }
+    }
+
+    this.#options = { persistent, recursive, signal, encoding };
+  }
+
+  close() {
+    if (this.#closed) {
+      return;
+    }
+
+    const { unwatchFile } = lazyLoadFsSync();
+    this.#closed = true;
+
+    for (const file of this.#files.keys()) {
+      unwatchFile(file);
+    }
+
+    this.#files.clear();
+    this.#symbolicFiles.clear();
+    this.emit('close');
+  }
+
+  #unwatchFiles(file) {
+    const { unwatchFile } = lazyLoadFsSync();
+
+    this.#symbolicFiles.delete(file);
+
+    for (const filename of this.#files.keys()) {
+      if (StringPrototypeStartsWith(filename, file)) {
+        unwatchFile(filename);
+      }
+    }
+  }
+
+  async #watchFolder(folder) {
+    const { opendir } = lazyLoadFsPromises();
+
+    try {
+      const files = await opendir(folder);
+
+      for await (const file of files) {
+        if (this.#closed) {
+          break;
+        }
+
+        const f = path.join(folder, file.name);
+
+        if (!this.#files.has(f)) {
+          this.emit('change', 'rename', path.relative(this.#rootPath, f));
+
+          if (file.isSymbolicLink()) {
+            this.#symbolicFiles.add(f);
+          }
+
+          if (file.isFile()) {
+            this.#watchFile(f);
+          } else {
+            this.#files.set(f, file);
+
+            if (file.isDirectory() && !file.isSymbolicLink()) {
+              await this.#watchFolder(f);
+            }
+          }
+        }
+      }
+    } catch (error) {
+      this.emit('error', error);
+    }
+  }
+
+  #watchFile(file) {
+    if (this.#closed) {
+      return;
+    }
+
+    const { watchFile } = lazyLoadFsSync();
+    const existingStat = this.#files.get(file);
+
+    watchFile(file, {
+      persistent: this.#options.persistent,
+    }, (currentStats, previousStats) => {
+      if (existingStat && !existingStat.isDirectory() &&
+        currentStats.nlink !== 0 && existingStat.mtimeMs === currentStats.mtimeMs) {
+        return;
+      }
+
+      this.#files.set(file, currentStats);
+
+      if (currentStats.birthtimeMs === 0 && previousStats.birthtimeMs !== 0) {
+        // The file is now deleted
+        this.#files.delete(file);
+        this.emit('change', 'rename', path.relative(this.#rootPath, file));
+        this.#unwatchFiles(file);
+      } else if (file === this.#rootPath && this.#watchingFile) {
+        // This case will only be triggered when watching a file with fs.watch
+        this.emit('change', 'change', path.basename(file));
+      } else if (this.#symbolicFiles.has(file)) {
+        // Stats from watchFile does not return correct value for currentStats.isSymbolicLink()
+        // Since it is only valid when using fs.lstat(). Therefore, check the existing symbolic files.
+        this.emit('change', 'rename', path.relative(this.#rootPath, file));
+      } else if (currentStats.isDirectory()) {
+        this.#watchFolder(file);
+      }
+    });
+  }
+
+  [kFSWatchStart](filename) {
+    filename = path.resolve(getValidatedPath(filename));
+
+    try {
+      const file = lazyLoadFsSync().statSync(filename);
+
+      this.#rootPath = filename;
+      this.#closed = false;
+      this.#watchingFile = file.isFile();
+
+      if (file.isDirectory()) {
+        this.#files.set(filename, file);
+
+        PromisePrototypeThen(
+          traverse(filename, this.#files, this.#symbolicFiles),
+          () => {
+            for (const f of this.#files.keys()) {
+              this.#watchFile(f);
+            }
+          },
+        );
+      } else {
+        this.#watchFile(filename);
+      }
+    } catch (error) {
+      if (error.code === 'ENOENT') {
+        error.filename = filename;
+        throw error;
+      }
+    }
+
+  }
+
+  ref() {
+    this.#files.forEach((file) => {
+      if (file instanceof StatWatcher) {
+        file.ref();
+      }
+    });
+  }
+
+  unref() {
+    this.#files.forEach((file) => {
+      if (file instanceof StatWatcher) {
+        file.unref();
+      }
+    });
+  }
+
+  [SymbolAsyncIterator]() {
+    const { signal } = this.#options;
+    const promiseExecutor = signal == null ?
+      (resolve) => {
+        this.once('change', (eventType, filename) => {
+          resolve({ __proto__: null, value: { eventType, filename } });
+        });
+      } : (resolve, reject) => {
+        const onAbort = () => reject(new AbortError(undefined, { cause: signal.reason }));
+        if (signal.aborted) return onAbort();
+        signal.addEventListener('abort', onAbort, { __proto__: null, once: true });
+        this.once('change', (eventType, filename) => {
+          signal.removeEventListener('abort', onAbort);
+          resolve({ __proto__: null, value: { eventType, filename } });
+        });
+      };
+    return {
+      next: () => (this.#closed ?
+        { __proto__: null, done: true } :
+        new Promise(promiseExecutor)),
+      [SymbolAsyncIterator]() { return this; },
+    };
+  }
+}
+
+module.exports = {
+  FSWatcher,
+  kFSWatchStart,
+};
diff --git a/test/parallel/test-bootstrap-modules.js b/test/parallel/test-bootstrap-modules.js
index 84bfbba8f03feb..bddeaace64411f 100644
--- a/test/parallel/test-bootstrap-modules.js
+++ b/test/parallel/test-bootstrap-modules.js
@@ -65,6 +65,7 @@ const expectedModules = new Set([
   'NativeModule internal/fs/dir',
   'NativeModule internal/fs/promises',
   'NativeModule internal/fs/read_file_context',
+  'NativeModule internal/fs/recursive_watch',
   'NativeModule internal/fs/rimraf',
   'NativeModule internal/fs/utils',
   'NativeModule internal/fs/watchers',
diff --git a/test/parallel/test-fs-watch-close-when-destroyed.js b/test/parallel/test-fs-watch-close-when-destroyed.js
index 2dfff953aa9214..d185599ee96a23 100644
--- a/test/parallel/test-fs-watch-close-when-destroyed.js
+++ b/test/parallel/test-fs-watch-close-when-destroyed.js
@@ -5,6 +5,13 @@
 
 const common = require('../common');
 
+// fs-watch on folders have limited capability in AIX.
+// The testcase makes use of folder watching, and causes
+// hang. This behavior is documented. Skip this for AIX.
+
+if (common.isAIX)
+  common.skip('folder watch capability is limited in AIX.');
+
 if (common.isIBMi)
   common.skip('IBMi does not support `fs.watch()`');
 
diff --git a/test/parallel/test-fs-watch-encoding.js b/test/parallel/test-fs-watch-encoding.js
index 13b4dc340e43cf..0ef0881a6b5142 100644
--- a/test/parallel/test-fs-watch-encoding.js
+++ b/test/parallel/test-fs-watch-encoding.js
@@ -19,6 +19,9 @@ const common = require('../common');
 if (common.isAIX)
   common.skip('folder watch capability is limited in AIX.');
 
+if (common.isIBMi)
+  common.skip('IBMi does not support `fs.watch()`');
+
 const fs = require('fs');
 const path = require('path');
 
diff --git a/test/parallel/test-fs-watch-enoent.js b/test/parallel/test-fs-watch-enoent.js
index b76fa825e251a7..0d5bfc97315d0e 100644
--- a/test/parallel/test-fs-watch-enoent.js
+++ b/test/parallel/test-fs-watch-enoent.js
@@ -25,11 +25,9 @@ tmpdir.refresh();
   const validateError = (err) => {
     assert.strictEqual(err.path, nonexistentFile);
     assert.strictEqual(err.filename, nonexistentFile);
-    assert.strictEqual(err.syscall, 'watch');
+    assert.ok(err.syscall === 'watch' || err.syscall === 'stat');
     if (err.code === 'ENOENT') {
-      assert.strictEqual(
-        err.message,
-        `ENOENT: no such file or directory, watch '${nonexistentFile}'`);
+      assert.ok(err.message.startsWith('ENOENT: no such file or directory'));
       assert.strictEqual(err.errno, UV_ENOENT);
       assert.strictEqual(err.code, 'ENOENT');
     } else {  // AIX
@@ -49,25 +47,27 @@ tmpdir.refresh();
 }
 
 {
-  const file = path.join(tmpdir.path, 'file-to-watch');
-  fs.writeFileSync(file, 'test');
-  const watcher = fs.watch(file, common.mustNotCall());
+  if (common.isOSX || common.isWindows) {
+    const file = path.join(tmpdir.path, 'file-to-watch');
+    fs.writeFileSync(file, 'test');
+    const watcher = fs.watch(file, common.mustNotCall());
 
-  const validateError = (err) => {
-    assert.strictEqual(err.path, nonexistentFile);
-    assert.strictEqual(err.filename, nonexistentFile);
-    assert.strictEqual(
-      err.message,
-      `ENOENT: no such file or directory, watch '${nonexistentFile}'`);
-    assert.strictEqual(err.errno, UV_ENOENT);
-    assert.strictEqual(err.code, 'ENOENT');
-    assert.strictEqual(err.syscall, 'watch');
-    fs.unlinkSync(file);
-    return true;
-  };
+    const validateError = (err) => {
+      assert.strictEqual(err.path, nonexistentFile);
+      assert.strictEqual(err.filename, nonexistentFile);
+      assert.strictEqual(
+        err.message,
+        `ENOENT: no such file or directory, watch '${nonexistentFile}'`);
+      assert.strictEqual(err.errno, UV_ENOENT);
+      assert.strictEqual(err.code, 'ENOENT');
+      assert.strictEqual(err.syscall, 'watch');
+      fs.unlinkSync(file);
+      return true;
+    };
 
-  watcher.on('error', common.mustCall(validateError));
+    watcher.on('error', common.mustCall(validateError));
 
-  // Simulate the invocation from the binding
-  watcher._handle.onchange(UV_ENOENT, 'ENOENT', nonexistentFile);
+    // Simulate the invocation from the binding
+    watcher._handle.onchange(UV_ENOENT, 'ENOENT', nonexistentFile);
+  }
 }
diff --git a/test/parallel/test-fs-watch-recursive-promise.js b/test/parallel/test-fs-watch-recursive-promise.js
new file mode 100644
index 00000000000000..cb00a35db27417
--- /dev/null
+++ b/test/parallel/test-fs-watch-recursive-promise.js
@@ -0,0 +1,94 @@
+'use strict';
+
+const common = require('../common');
+
+if (common.isIBMi)
+  common.skip('IBMi does not support `fs.watch()`');
+
+// fs-watch on folders have limited capability in AIX.
+// The testcase makes use of folder watching, and causes
+// hang. This behavior is documented. Skip this for AIX.
+
+if (common.isAIX)
+  common.skip('folder watch capability is limited in AIX.');
+
+const assert = require('assert');
+const path = require('path');
+const fs = require('fs/promises');
+const fsSync = require('fs');
+
+const tmpdir = require('../common/tmpdir');
+const testDir = tmpdir.path;
+tmpdir.refresh();
+
+(async function run() {
+  // Add a file to already watching folder
+
+  const testsubdir = await fs.mkdtemp(testDir + path.sep);
+  const file = '1.txt';
+  const filePath = path.join(testsubdir, file);
+  const watcher = fs.watch(testsubdir, { recursive: true });
+
+  let interval;
+
+  process.on('exit', function() {
+    assert.ok(interval === null, 'watcher Object was not closed');
+  });
+
+  process.nextTick(common.mustCall(() => {
+    interval = setInterval(() => {
+      fsSync.writeFileSync(filePath, 'world');
+    }, 500);
+  }));
+
+  for await (const payload of watcher) {
+    const { eventType, filename } = payload;
+
+    assert.ok(eventType === 'change' || eventType === 'rename');
+
+    if (filename === file) {
+      break;
+    }
+  }
+
+  clearInterval(interval);
+  interval = null;
+})().then(common.mustCall());
+
+(async function() {
+  // Test that aborted AbortSignal are reported.
+  const testsubdir = await fs.mkdtemp(testDir + path.sep);
+  const error = new Error();
+  const watcher = fs.watch(testsubdir, { recursive: true, signal: AbortSignal.abort(error) });
+  await assert.rejects(async () => {
+    // eslint-disable-next-line no-unused-vars
+    for await (const _ of watcher);
+  }, { code: 'ABORT_ERR', cause: error });
+})().then(common.mustCall());
+
+(async function() {
+  // Test that with AbortController.
+  const testsubdir = await fs.mkdtemp(testDir + path.sep);
+  const file = '2.txt';
+  const filePath = path.join(testsubdir, file);
+  const error = new Error();
+  const ac = new AbortController();
+  const watcher = fs.watch(testsubdir, { recursive: true, signal: ac.signal });
+  let interval;
+  process.on('exit', function() {
+    assert.ok(interval === null, 'watcher Object was not closed');
+  });
+  process.nextTick(common.mustCall(() => {
+    interval = setInterval(() => {
+      fsSync.writeFileSync(filePath, 'world');
+    }, 50);
+    ac.abort(error);
+  }));
+  await assert.rejects(async () => {
+    for await (const { eventType } of watcher) {
+      assert.ok(eventType === 'change' || eventType === 'rename');
+    }
+  }, { code: 'ABORT_ERR', cause: error });
+  clearInterval(interval);
+  interval = null;
+})().then(common.mustCall());
diff --git a/test/parallel/test-fs-watch-recursive-symlink.js b/test/parallel/test-fs-watch-recursive-symlink.js
new file mode 100644
index 00000000000000..602ec58eab0d7a
--- /dev/null
+++ b/test/parallel/test-fs-watch-recursive-symlink.js
@@ -0,0 +1,100 @@
+'use strict';
+
+const common = require('../common');
+const { setTimeout } = require('timers/promises');
+
+if (common.isIBMi)
+  common.skip('IBMi does not support `fs.watch()`');
+
+// fs-watch on folders have limited capability in AIX.
+// The testcase makes use of folder watching, and causes
+// hang. This behavior is documented. Skip this for AIX.
+
+if (common.isAIX)
+  common.skip('folder watch capability is limited in AIX.');
+
+const assert = require('assert');
+const path = require('path');
+const fs = require('fs');
+
+const tmpdir = require('../common/tmpdir');
+const testDir = tmpdir.path;
+tmpdir.refresh();
+
+(async () => {
+  // Add a recursive symlink to the parent folder
+
+  const testDirectory = fs.mkdtempSync(testDir + path.sep);
+
+  // Do not use `testDirectory` as base. It will hang the tests.
+  const rootDirectory = path.join(testDirectory, 'test-1');
+  fs.mkdirSync(rootDirectory);
+
+  const filePath = path.join(rootDirectory, 'file.txt');
+
+  const symlinkFolder = path.join(rootDirectory, 'symlink-folder');
+  fs.symlinkSync(rootDirectory, symlinkFolder);
+
+
+  const watcher = fs.watch(rootDirectory, { recursive: true });
+  let watcherClosed = false;
+  watcher.on('change', function(event, filename) {
+    assert.ok(event === 'rename', `Received ${event}`);
+    assert.ok(filename === path.basename(symlinkFolder) || filename === path.basename(filePath), `Received ${filename}`);
+
+    if (filename === path.basename(filePath)) {
+      watcher.close();
+      watcherClosed = true;
+    }
+  });
+
+  await setTimeout(common.platformTimeout(100));
+  fs.writeFileSync(filePath, 'world');
+
+  process.once('exit', function() {
+    assert(watcherClosed, 'watcher Object was not closed');
+  });
+})().then(common.mustCall());
+
+(async () => {
+  // This test checks how a symlink to outside the tracking folder can trigger change
+  // tmp/sub-directory/tracking-folder/symlink-folder -> tmp/sub-directory
+
+  const rootDirectory = fs.mkdtempSync(testDir + path.sep);
+
+  const subDirectory = path.join(rootDirectory, 'sub-directory');
+  fs.mkdirSync(subDirectory);
+
+  const trackingSubDirectory = path.join(subDirectory, 'tracking-folder');
+  fs.mkdirSync(trackingSubDirectory);
+
+  const symlinkFolder = path.join(trackingSubDirectory, 'symlink-folder');
+  fs.symlinkSync(subDirectory, symlinkFolder);
+
+  const forbiddenFile = path.join(subDirectory, 'forbidden.txt');
+  const acceptableFile = path.join(trackingSubDirectory, 'acceptable.txt');
+
+  const watcher = fs.watch(trackingSubDirectory, { recursive: true });
+  let watcherClosed = false;
+  watcher.on('change', function(event, filename) {
+    // macOS will only change the following events:
+    // { event: 'rename', filename: 'symlink-folder' }
+    // { event: 'rename', filename: 'acceptable.txt' }
+    assert.ok(event === 'rename', `Received ${event}`);
+    assert.ok(filename === path.basename(symlinkFolder) || filename === path.basename(acceptableFile), `Received ${filename}`);
+
+    if (filename === path.basename(acceptableFile)) {
+      watcher.close();
+      watcherClosed = true;
+    }
+  });
+
+  await setTimeout(common.platformTimeout(100));
+  fs.writeFileSync(forbiddenFile, 'world');
+  await setTimeout(common.platformTimeout(100));
+  fs.writeFileSync(acceptableFile, 'acceptable');
+
+  process.once('exit', function() {
+    assert(watcherClosed, 'watcher Object was not closed');
+  });
+})().then(common.mustCall());
diff --git a/test/parallel/test-fs-watch-recursive.js b/test/parallel/test-fs-watch-recursive.js
index 70b413814e78f4..a4c22bfbd2ce11 100644
--- a/test/parallel/test-fs-watch-recursive.js
+++ b/test/parallel/test-fs-watch-recursive.js
@@ -1,54 +1,227 @@
 'use strict';
 
 const common = require('../common');
+const { setTimeout } = require('timers/promises');
 
+if (common.isIBMi)
+  common.skip('IBMi does not support `fs.watch()`');
+
+// fs-watch on folders have limited capability in AIX.
+// The testcase makes use of folder watching, and causes
+// hang. This behavior is documented. Skip this for AIX.
+
+if (common.isAIX)
+  common.skip('folder watch capability is limited in AIX.');
 
 const assert = require('assert');
 const path = require('path');
 const fs = require('fs');
+const { pathToFileURL } = require('url');
 
 const tmpdir = require('../common/tmpdir');
-
 const testDir = tmpdir.path;
-const filenameOne = 'watch.txt';
-
 tmpdir.refresh();
 
-const testsubdir = fs.mkdtempSync(testDir + path.sep);
-const relativePathOne = path.join(path.basename(testsubdir), filenameOne);
-const filepathOne = path.join(testsubdir, filenameOne);
+(async () => {
+  // Add a file to already watching folder
+
+  const rootDirectory = fs.mkdtempSync(testDir + path.sep);
+  const testDirectory = path.join(rootDirectory, 'test-1');
+  fs.mkdirSync(testDirectory);
+
+  const testFile = path.join(testDirectory, 'file-1.txt');
+
+  const watcher = fs.watch(testDirectory, { recursive: true });
+  let watcherClosed = false;
+  watcher.on('change', function(event, filename) {
+    assert.ok(event === 'rename');
+
+    if (filename === path.basename(testFile)) {
+      watcher.close();
+      watcherClosed = true;
+    }
+  });
+
+  await setTimeout(common.platformTimeout(100));
+  fs.writeFileSync(testFile, 'world');
+
+  process.once('exit', function() {
+    assert(watcherClosed, 'watcher Object was not closed');
+  });
+})().then(common.mustCall());
+
+(async () => {
+  // Add a folder to already watching folder
+
+  const rootDirectory = fs.mkdtempSync(testDir + path.sep);
+  const testDirectory = path.join(rootDirectory, 'test-2');
+  fs.mkdirSync(testDirectory);
+
+  const testFile = path.join(testDirectory, 'folder-2');
+
+  const watcher = fs.watch(testDirectory, { recursive: true });
+  let watcherClosed = false;
+  watcher.on('change', function(event, filename) {
+    assert.ok(event === 'rename');
+
+    if (filename === path.basename(testFile)) {
+      watcher.close();
+      watcherClosed = true;
+    }
+  });
+
+  await setTimeout(common.platformTimeout(100));
+  fs.mkdirSync(testFile);
+
+  process.once('exit', function() {
+    assert(watcherClosed, 'watcher Object was not closed');
+  });
+})().then(common.mustCall());
+
+(async () => {
+  // Add a file to newly created folder to already watching folder
+
+  const rootDirectory = fs.mkdtempSync(testDir + path.sep);
+  const testDirectory = path.join(rootDirectory, 'test-3');
+  fs.mkdirSync(testDirectory);
+
+  const filePath = path.join(testDirectory, 'folder-3');
+
+  const childrenFile = 'file-4.txt';
+  const childrenAbsolutePath = path.join(filePath, childrenFile);
+  const childrenRelativePath = path.join(path.basename(filePath), childrenFile);
+
+  const watcher = fs.watch(testDirectory, { recursive: true });
+  let watcherClosed = false;
+  watcher.on('change', function(event, filename) {
+    assert.ok(event === 'rename');
+    assert.ok(filename === path.basename(filePath) || filename === childrenRelativePath);
+
+    if (filename === childrenRelativePath) {
+      watcher.close();
+      watcherClosed = true;
+    }
+  });
+
+  await setTimeout(common.platformTimeout(100));
+  fs.mkdirSync(filePath);
+  await setTimeout(common.platformTimeout(100));
+  fs.writeFileSync(childrenAbsolutePath, 'world');
+
+  process.once('exit', function() {
+    assert(watcherClosed, 'watcher Object was not closed');
+  });
+})().then(common.mustCall());
+
+(async () => {
+  // Add a file to subfolder of a watching folder
+
+  const rootDirectory = fs.mkdtempSync(testDir + path.sep);
+  const testDirectory = path.join(rootDirectory, 'test-4');
+  fs.mkdirSync(testDirectory);
+
+  const file = 'folder-5';
+  const filePath = path.join(testDirectory, file);
+  fs.mkdirSync(filePath);
+
+  const subfolderPath = path.join(filePath, 'subfolder-6');
+  fs.mkdirSync(subfolderPath);
+
+  const childrenFile = 'file-7.txt';
+  const childrenAbsolutePath = path.join(subfolderPath, childrenFile);
+  const relativePath = path.join(file, path.basename(subfolderPath), childrenFile);
+
+  const watcher = fs.watch(testDirectory, { recursive: true });
+  let watcherClosed = false;
+  watcher.on('change', function(event, filename) {
+    assert.ok(event === 'rename');
+
+    if (filename === relativePath) {
+      watcher.close();
+      watcherClosed = true;
+    }
+  });
+
+  await setTimeout(common.platformTimeout(100));
+  fs.writeFileSync(childrenAbsolutePath, 'world');
+
+  process.once('exit', function() {
+    assert(watcherClosed, 'watcher Object was not closed');
+  });
+})().then(common.mustCall());
+
+(async () => {
+  // Add a file to already watching folder, and use URL as the path
+
+  const rootDirectory = fs.mkdtempSync(testDir + path.sep);
+  const testDirectory = path.join(rootDirectory, 'test-5');
+  fs.mkdirSync(testDirectory);
+
+  const filePath = path.join(testDirectory, 'file-8.txt');
+  const url = pathToFileURL(testDirectory);
+
+  const watcher = fs.watch(url, { recursive: true });
+  let watcherClosed = false;
+  watcher.on('change', function(event, filename) {
+    assert.ok(event === 'rename');
+
+    if (filename === path.basename(filePath)) {
+      watcher.close();
+      watcherClosed = true;
+    }
+  });
+
+  await setTimeout(common.platformTimeout(100));
+  fs.writeFileSync(filePath, 'world');
+
+  process.on('exit', function() {
+    assert(watcherClosed, 'watcher Object was not closed');
+  });
+})().then(common.mustCall());
+
+(async () => {
+  // Watch a file (not a folder) using fs.watch
+
+  const rootDirectory = fs.mkdtempSync(testDir + path.sep);
+  const testDirectory = path.join(rootDirectory, 'test-6');
+  fs.mkdirSync(testDirectory);
+
+  const filePath = path.join(testDirectory, 'only-file.txt');
+  fs.writeFileSync(filePath, 'hello');
+
+  const watcher = fs.watch(filePath, { recursive: true });
+  let watcherClosed = false;
+  let interval;
+  watcher.on('change', function(event, filename) {
+    assert.ok(event === 'change');
+
+    if (filename === path.basename(filePath)) {
+      clearInterval(interval);
+      interval = null;
+      watcher.close();
+      watcherClosed = true;
+    }
+  });
 
-if (!common.isOSX && !common.isWindows) {
-  assert.throws(() => { fs.watch(testDir, { recursive: true }); },
-                { code: 'ERR_FEATURE_UNAVAILABLE_ON_PLATFORM' });
-  return;
-}
-const watcher = fs.watch(testDir, { recursive: true });
+  interval = setInterval(() => {
+    fs.writeFileSync(filePath, 'world');
+  }, common.platformTimeout(10));
 
-let watcherClosed = false;
-watcher.on('change', function(event, filename) {
-  assert.ok(event === 'change' || event === 'rename');
+  process.on('exit', function() {
+    assert(watcherClosed, 'watcher Object was not closed');
+    assert.ok(interval === null, 'interval should have been null');
+  });
+})().then(common.mustCall());
 
-  // Ignore stale events generated by mkdir and other tests
-  if (filename !== relativePathOne)
-    return;
+(async () => {
+  // Handle non-boolean values for options.recursive
 
-  if (common.isOSX) {
-    clearInterval(interval);
+  if (!common.isWindows && !common.isOSX) {
+    assert.throws(() => {
+      const testsubdir = fs.mkdtempSync(testDir + path.sep);
+      fs.watch(testsubdir, { recursive: '1' });
+    }, {
+      code: 'ERR_INVALID_ARG_TYPE',
+    });
   }
-  watcher.close();
-  watcherClosed = true;
-});
-
-let interval;
-if (common.isOSX) {
-  interval = setInterval(function() {
-    fs.writeFileSync(filepathOne, 'world');
-  }, 10);
-} else {
-  fs.writeFileSync(filepathOne, 'world');
-}
-
-process.on('exit', function() {
-  assert(watcherClosed, 'watcher Object was not closed');
-});
+})().then(common.mustCall());
diff --git a/test/parallel/test-fs-watchfile.js b/test/parallel/test-fs-watchfile.js
index 8d1241bae8f1c2..4a94b16f9b63f2 100644
--- a/test/parallel/test-fs-watchfile.js
+++ b/test/parallel/test-fs-watchfile.js
@@ -90,9 +90,9 @@ if (common.isLinux || common.isOSX || common.isWindows) {
   fs.mkdir(dir, common.mustCall(function(err) {
     if (err) assert.fail(err);
 
-    fs.watch(dir, common.mustCall(function(eventType, filename) {
+    const handle = fs.watch(dir, common.mustCall(function(eventType, filename) {
       clearInterval(interval);
-      this._handle.close();
+      handle.close();
       assert.strictEqual(filename, 'foo.txt');
     }));
 
diff --git a/test/sequential/test-fs-watch.js b/test/sequential/test-fs-watch.js
index c5db585f3f4a59..d94021072af498 100644
--- a/test/sequential/test-fs-watch.js
+++ b/test/sequential/test-fs-watch.js
@@ -124,41 +124,45 @@ function repeat(fn) {
 // Whitebox test to ensure that wrapped FSEvent is safe
 // https://github.com/joyent/node/issues/6690
 {
-  let oldhandle;
-  assert.throws(
-    () => {
-      const w = fs.watch(__filename, common.mustNotCall());
-      oldhandle = w._handle;
-      w._handle = { close: w._handle.close };
-      w.close();
-    },
-    {
-      name: 'Error',
-      code: 'ERR_INTERNAL_ASSERTION',
-      message: /^handle must be a FSEvent/,
-    }
-  );
-  oldhandle.close(); // clean up
+  if (common.isOSX || common.isWindows) {
+    let oldhandle;
+    assert.throws(
+      () => {
+        const w = fs.watch(__filename, common.mustNotCall());
+        oldhandle = w._handle;
+        w._handle = { close: w._handle.close };
+        w.close();
+      },
+      {
+        name: 'Error',
+        code: 'ERR_INTERNAL_ASSERTION',
+        message: /^handle must be a FSEvent/,
+      }
+    );
+    oldhandle.close(); // clean up
+  }
 }
 
 {
-  let oldhandle;
-  assert.throws(
-    () => {
-      const w = fs.watch(__filename, common.mustNotCall());
-      oldhandle = w._handle;
-      const protoSymbols =
-        Object.getOwnPropertySymbols(Object.getPrototypeOf(w));
-      const kFSWatchStart =
-        protoSymbols.find((val) => val.toString() === 'Symbol(kFSWatchStart)');
-      w._handle = {};
-      w[kFSWatchStart]();
-    },
-    {
-      name: 'Error',
-      code: 'ERR_INTERNAL_ASSERTION',
-      message: /^handle must be a FSEvent/,
-    }
-  );
-  oldhandle.close(); // clean up
+  if (common.isOSX || common.isWindows) {
+    let oldhandle;
+    assert.throws(
+      () => {
+        const w = fs.watch(__filename, common.mustNotCall());
+        oldhandle = w._handle;
+        const protoSymbols =
+          Object.getOwnPropertySymbols(Object.getPrototypeOf(w));
+        const kFSWatchStart =
+          protoSymbols.find((val) => val.toString() === 'Symbol(kFSWatchStart)');
+        w._handle = {};
+        w[kFSWatchStart]();
+      },
+      {
+        name: 'Error',
+        code: 'ERR_INTERNAL_ASSERTION',
+        message: /^handle must be a FSEvent/,
+      }
+    );
+    oldhandle.close(); // clean up
+  }
 }