Implement `__dirname` and `__filename`, allow direct eval in CommonJS (#3164)

* Implement `__dirname` and `__filename`, allow direct eval in CommonJS

* Fixup dirname and add test

---------

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

1 files changed, 18 insertions, 3 deletions

diff --git a/src/bun.js/bindings/CommonJSModuleRecord.cpp b/src/bun.js/bindings/CommonJSModuleRecord.cpp
index e3bf3a0db..a32d722d9 100644
--- a/src/bun.js/bindings/CommonJSModuleRecord.cpp
+++ b/src/bun.js/bindings/CommonJSModuleRecord.cpp
@@ -218,7 +218,7 @@ static Structure* internalCreateCommonJSModuleStructure(
     structure = structure->addPropertyTransition(
         vm,
         structure,
-        JSC::Identifier::fromString(vm, "fileName"_s),
+        JSC::Identifier::fromString(vm, "filename"_s),
         0,
         offset);
 
@@ -310,10 +310,15 @@ JSC::SourceCode createCommonJSModule(
                     ? JSC::constructEmptyObject(globalObject, globalObject->objectPrototype(), source.commonJSExportsLen)
                     : JSC::constructEmptyObject(globalObject, globalObject->objectPrototype());
 
-                if (!globalObject->requireMap()->has(globalObject, requireMapKey)) {
-                    globalObject->requireMap()->set(globalObject, requireMapKey, exportsObject);
+                auto index = sourceURL.reverseFind('/', sourceURL.length());
+                JSString* dirname = jsEmptyString(vm);
+                JSString* filename = requireMapKey;
+                if (index != WTF::notFound) {
+                    dirname = JSC::jsSubstring(globalObject, requireMapKey, 0, index);
                 }
 
+                globalObject->requireMap()->set(globalObject, requireMapKey, exportsObject);
+
                 JSC::SourceCode inputSource(
                     JSC::StringSourceProvider::create(sourceCodeString,
                         JSC::SourceOrigin(WTF::URL::fileURLWithFileSystemPath(sourceURL)),
@@ -344,6 +349,16 @@ JSC::SourceCode createCommonJSModule(
                 scopeExtensionObject->putDirectOffset(
                     vm,
                     2,
+                    dirname);
+
+                scopeExtensionObject->putDirectOffset(
+                    vm,
+                    3,
+                    filename);
+
+                scopeExtensionObject->putDirectOffset(
+                    vm,
+                    4,
                     requireFunction);
 
                 auto* executable = JSC::DirectEvalExecutable::create(