worker,fs: make FileHandle transferable

Allow passing `FileHandle` instances in the transfer list
of a `.postMessage()` call.

PR-URL: https://github.com/nodejs/node/pull/33772
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

1 files changed, 26 insertions, 2 deletions

diff --git a/lib/internal/fs/promises.js b/lib/internal/fs/promises.js
index 05d82991552..717b26e59fa 100644
--- a/lib/internal/fs/promises.js
+++ b/lib/internal/fs/promises.js
@@ -65,13 +65,17 @@ const { promisify } = require('internal/util');
 const kHandle = Symbol('kHandle');
 const kFd = Symbol('kFd');
 const { kUsePromises } = binding;
+const {
+  JSTransferable, kDeserialize, kTransfer, kTransferList
+} = require('internal/worker/js_transferable');
 
 const getDirectoryEntriesPromise = promisify(getDirents);
 
-class FileHandle {
+class FileHandle extends JSTransferable {
   constructor(filehandle) {
+    super();
     this[kHandle] = filehandle;
-    this[kFd] = filehandle.fd;
+    this[kFd] = filehandle ? filehandle.fd : -1;
   }
 
   getAsyncId() {
@@ -142,6 +146,26 @@ class FileHandle {
     this[kFd] = -1;
     return this[kHandle].close();
   }
+
+  [kTransfer]() {
+    const handle = this[kHandle];
+    this[kFd] = -1;
+    this[kHandle] = null;
+
+    return {
+      data: { handle },
+      deserializeInfo: 'internal/fs/promises:FileHandle'
+    };
+  }
+
+  [kTransferList]() {
+    return [ this[kHandle] ];
+  }
+
+  [kDeserialize]({ handle }) {
+    this[kHandle] = handle;
+    this[kFd] = handle.fd;
+  }
 }
 
 function validateFileHandle(handle) {