ffi: prevent premature GC of DynamicLibrary

semimikoh · web-flow · commit 9c0101860e77 · 2026-05-01T09:52:10.000Z
Signed-off-by: semimikoh <ejffjeosms@gmail.com> PR-URL: #63024 Fixes: #63010 Reviewed-By: Paolo Insogna <paolo@cowtech.it> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: Bryan English <bryan@bryanenglish.com>
diff --git a/src/node_ffi.cc b/src/node_ffi.cc
@@ -194,6 +194,7 @@ void DynamicLibrary::CleanupFunctionInfo(
   FFIFunctionInfo* info = data.GetParameter();
   info->fn.reset();
   info->self.Reset();
+  info->library.Reset();
   delete info;
 }
 
@@ -313,6 +314,7 @@ MaybeLocal<Function> DynamicLibrary::CreateFunction(
   }
 
   info->self.Reset(isolate, ret);
+  info->library.Reset(isolate, object());
   info->self.SetWeak(info.release(),
                      DynamicLibrary::CleanupFunctionInfo,
                      WeakCallbackType::kParameter);
diff --git a/src/node_ffi.h b/src/node_ffi.h
@@ -33,6 +33,8 @@ struct FFIFunctionInfo {
   std::shared_ptr<FFIFunction> fn;
   v8::Global<v8::Function> self;
   std::shared_ptr<v8::BackingStore> sb_backing;
+  // Keep the owning DynamicLibrary alive while the generated function is alive.
+  v8::Global<v8::Object> library;
 };
 
 struct FFICallback {
diff --git a/test/ffi/test-ffi-dynamic-library.js b/test/ffi/test-ffi-dynamic-library.js
@@ -1,7 +1,8 @@
-// Flags: --experimental-ffi
+// Flags: --experimental-ffi --expose-gc
 'use strict';
 const common = require('../common');
 common.skipIfFFIMissing();
+const { gcUntil } = require('../common/gc');
 const assert = require('node:assert');
 const { test } = require('node:test');
 const ffi = require('node:ffi');
@@ -117,6 +118,27 @@ test('getFunction caches signatures consistently', () => {
   }
 });
 
+test('FFI functions keep their owning library alive', async () => {
+  let lib = new ffi.DynamicLibrary(libraryPath);
+  const addI32 = lib.getFunction('add_i32', fixtureSymbols.add_i32);
+  const ref = new WeakRef(lib);
+
+  lib = null;
+
+  for (let i = 0; i < 5; i++) {
+    await gcUntil(
+      'FFI function keeps its owning library alive',
+      () => true,
+      1,
+    );
+    assert.ok(ref.deref() instanceof ffi.DynamicLibrary);
+    assert.strictEqual(addI32(20, 22), 42);
+  }
+
+  ref.deref().close();
+  assert.throws(() => addI32(20, 22), /Library is closed/);
+});
+
 test('closed libraries reject subsequent operations', () => {
   const { lib, functions } = ffi.dlopen(libraryPath, {
     add_i32: fixtureSymbols.add_i32,

Original file line number	Diff line number	Diff line change
`@@ -194,6 +194,7 @@ void DynamicLibrary::CleanupFunctionInfo(`
`194`	`194`	`FFIFunctionInfo* info = data.GetParameter();`
`195`	`195`	`info->fn.reset();`
`196`	`196`	`info->self.Reset();`
	`197`	`+ info->library.Reset();`
`197`	`198`	`delete info;`
`198`	`199`	`}`
`199`	`200`
`@@ -313,6 +314,7 @@ MaybeLocal<Function> DynamicLibrary::CreateFunction(`
`313`	`314`	`}`
`314`	`315`
`315`	`316`	`info->self.Reset(isolate, ret);`
	`317`	`+ info->library.Reset(isolate, object());`
`316`	`318`	`info->self.SetWeak(info.release(),`
`317`	`319`	`DynamicLibrary::CleanupFunctionInfo,`
`318`	`320`	`WeakCallbackType::kParameter);`