Make readdir() async, fix crash in large directory trees (#3838)

* Fix unsafe GC behavior on large arrays returned by fs

* Fix crash in large arrays of strings

* async readdir

* Add tests for large number of files returned by readdir

* Move this down

* Fix encoding edgecase in path.join

* Async stat & lstat

* add test

---------

Co-authored-by: Jarred Sumner <709451+Jarred-Sumner@users.noreply.github.com>

1 files changed, 33 insertions, 17 deletions

diff --git a/src/bun.js/bindings/BunString.cpp b/src/bun.js/bindings/BunString.cpp
index 714f10080..e044730c4 100644
--- a/src/bun.js/bindings/BunString.cpp
+++ b/src/bun.js/bindings/BunString.cpp
@@ -256,31 +256,47 @@ extern "C" EncodedJSValue BunString__createArray(
     auto& vm = globalObject->vm();
     auto throwScope = DECLARE_THROW_SCOPE(vm);
 
-    // We must do this or Bun.gc(true) in a loop creating large arrays of strings will crash due to GC'ing.
-    MarkedArgumentBuffer arguments;
-    JSC::ObjectInitializationScope scope(vm);
-    GCDeferralContext context(vm);
-
-    arguments.fill(length, [&](JSC::JSValue* value) {
-        const BunString* end = ptr + length;
-        while (ptr != end) {
-            *value++ = Bun::toJS(globalObject, *ptr++);
-        }
-    });
+    if (length < 64) {
+        // We must do this or Bun.gc(true) in a loop creating large arrays of strings will crash due to GC'ing.
+        MarkedArgumentBuffer arguments;
+
+        arguments.fill(length, [&](JSC::JSValue* value) {
+            const BunString* end = ptr + length;
+            while (ptr != end) {
+                *value++ = Bun::toJS(globalObject, *ptr++);
+            }
+        });
+
+        JSC::ObjectInitializationScope scope(vm);
+        GCDeferralContext context(vm);
 
-    if (JSC::JSArray* array = JSC::JSArray::tryCreateUninitializedRestricted(
+        JSC::JSArray* array = JSC::JSArray::tryCreateUninitializedRestricted(
             scope,
             globalObject->arrayStructureForIndexingTypeDuringAllocation(JSC::ArrayWithContiguous),
-            length)) {
+            length);
+
+        if (array) {
+            for (size_t i = 0; i < length; ++i) {
+                array->initializeIndex(scope, i, arguments.at(i));
+            }
+            return JSValue::encode(array);
+        }
+
+        JSC::throwOutOfMemoryError(globalObject, throwScope);
+        RELEASE_AND_RETURN(throwScope, JSValue::encode(JSC::JSValue()));
+    } else {
+        JSC::JSArray* array = constructEmptyArray(globalObject, nullptr, length);
+        if (!array) {
+            JSC::throwOutOfMemoryError(globalObject, throwScope);
+            RELEASE_AND_RETURN(throwScope, JSValue::encode(JSC::JSValue()));
+        }
 
         for (size_t i = 0; i < length; ++i) {
-            array->initializeIndex(scope, i, arguments.at(i));
+            array->putDirectIndex(globalObject, i, Bun::toJS(globalObject, *ptr++));
         }
+
         return JSValue::encode(array);
     }
-
-    JSC::throwOutOfMemoryError(globalObject, throwScope);
-    RELEASE_AND_RETURN(throwScope, JSValue::encode(JSC::JSValue()));
 }
 
 extern "C" void BunString__toWTFString(BunString* bunString)