Issue #1691 - Part 1: Provide a way of associating a private value with a script or module.

This is a prerequisite for dynamic import

(cherry picked from commit 2e2972647ee29340df51a804f05e40fc1da2c89b)

dom/script/ModuleScript.cpp

@@ -58,9 +58,9 @@ ModuleScript::UnlinkModuleRecord()
 {
   // Remove module's back reference to this object request if present.
   if (mModuleRecord) {
-    MOZ_ASSERT(JS::GetModuleHostDefinedField(mModuleRecord).toPrivate() ==
+    MOZ_ASSERT(JS::GetModulePrivate(mModuleRecord).toPrivate() ==
                this);
-    JS::SetModuleHostDefinedField(mModuleRecord, JS::UndefinedValue());
+    JS::SetModulePrivate(mModuleRecord, JS::UndefinedValue());
     mModuleRecord = nullptr;
   }
 }
@@ -83,7 +83,7 @@ ModuleScript::SetModuleRecord(JS::Handle<JSObject*> aModuleRecord)
 
   // Make module's host defined field point to this module script object.
   // This is cleared in the UnlinkModuleRecord().
-  JS::SetModuleHostDefinedField(mModuleRecord, JS::PrivateValue(this));
+  JS::SetModulePrivate(mModuleRecord, JS::PrivateValue(this));
   HoldJSObjects(this);
 }
 

dom/script/ScriptLoader.cpp

@@ -798,13 +798,13 @@ ScriptLoader::StartFetchingModuleAndDependencies(ModuleLoadRequest* aParent,
 
 // 8.1.3.8.1 HostResolveImportedModule(referencingModule, specifier)
 JSObject*
-HostResolveImportedModule(JSContext* aCx, JS::Handle<JSObject*> aModule,
+HostResolveImportedModule(JSContext* aCx,
+                          JS::Handle<JS::Value> aReferencingPrivate,
                           JS::Handle<JSString*> aSpecifier)
 {
   // Let referencing module script be referencingModule.[[HostDefined]].
-  JS::Value value = JS::GetModuleHostDefinedField(aModule);
+  auto script = static_cast<ModuleScript*>(aReferencingPrivate.toPrivate());
-  auto script = static_cast<ModuleScript*>(value.toPrivate());
+  MOZ_ASSERT(JS::GetModulePrivate(script->ModuleRecord()) == aReferencingPrivate);
-  MOZ_ASSERT(script->ModuleRecord() == aModule);
 
   // Let url be the result of resolving a module specifier given referencing
   // module script and specifier.

dom/script/ScriptLoader.h

@@ -630,8 +630,9 @@ private:
   ModuleScript* GetFetchedModule(nsIURI* aURL) const;
 
   friend JSObject*
-  HostResolveImportedModule(JSContext* aCx, JS::Handle<JSObject*> aModule,
+  HostResolveImportedModule(JSContext* aCx,
-                          JS::Handle<JSString*> aSpecifier);
+                            JS::Handle<JS::Value> aReferencingPrivate,
+                            JS::Handle<JSString*> aSpecifier);
 
   nsresult CreateModuleScript(ModuleLoadRequest* aRequest);
   nsresult ProcessFetchedModuleSource(ModuleLoadRequest* aRequest);

js/src/builtin/ModuleObject.cpp

@@ -725,6 +725,12 @@ ModuleObject::namespace_()
     return &value.toObject().as<ModuleNamespaceObject>();
 }
 
+ScriptSourceObject*
+ModuleObject::scriptSourceObject() const
+{
+    return &getReservedSlot(ScriptSourceObjectSlot).toObject().as<ScriptSourceObject>();
+}
+
 FunctionDeclarationVector*
 ModuleObject::functionDeclarations()
 {
@@ -738,8 +744,10 @@ ModuleObject::functionDeclarations()
 void
 ModuleObject::init(HandleScript script)
 {
+    MOZ_ASSERT(script);
     initReservedSlot(ScriptSlot, PrivateValue(script));
     initReservedSlot(StatusSlot, Int32Value(MODULE_STATUS_UNINSTANTIATED));
+    initReservedSlot(ScriptSourceObjectSlot, ObjectValue(script->scriptSourceUnwrap()));
 }
 
 void
@@ -868,18 +876,6 @@ ModuleObject::evaluationError() const
     return getReservedSlot(EvaluationErrorSlot);
 }
 
-Value
-ModuleObject::hostDefinedField() const
-{
-    return getReservedSlot(HostDefinedSlot);
-}
-
-void
-ModuleObject::setHostDefinedField(const JS::Value& value)
-{
-    setReservedSlot(HostDefinedSlot, value);
-}
-
 Scope*
 ModuleObject::enclosingScope() const
 {

js/src/builtin/ModuleObject.h

@@ -221,7 +221,7 @@ class ModuleObject : public NativeObject
         NamespaceSlot,
         StatusSlot,
         EvaluationErrorSlot,
-        HostDefinedSlot,
+        ScriptSourceObjectSlot,
         RequestedModulesSlot,
         ImportEntriesSlot,
         LocalExportEntriesSlot,
@@ -273,7 +273,7 @@ class ModuleObject : public NativeObject
     ModuleStatus status() const;
     bool hadEvaluationError() const;
     Value evaluationError() const;
-    Value hostDefinedField() const;
+    ScriptSourceObject* scriptSourceObject() const;
     ArrayObject& requestedModules() const;
     ArrayObject& importEntries() const;
     ArrayObject& localExportEntries() const;
@@ -286,8 +286,6 @@ class ModuleObject : public NativeObject
     static bool Instantiate(JSContext* cx, HandleModuleObject self);
     static bool Evaluate(JSContext* cx, HandleModuleObject self);
 
-    void setHostDefinedField(const JS::Value& value);
-
     // For BytecodeEmitter.
     bool noteFunctionDeclaration(ExclusiveContext* cx, HandleAtom name, HandleFunction fun);
 

js/src/jsapi.cpp

@@ -4710,15 +4710,27 @@ JS::CompileModule(JSContext* cx, const ReadOnlyCompileOptions& options,
 }
 
 JS_PUBLIC_API(void)
-JS::SetModuleHostDefinedField(JSObject* module, const JS::Value& value)
+JS::SetModulePrivate(JSObject* module, const JS::Value& value)
 {
-    module->as<ModuleObject>().setHostDefinedField(value);
+    module->as<ModuleObject>().scriptSourceObject()->setPrivate(value);
 }
 
 JS_PUBLIC_API(JS::Value)
-JS::GetModuleHostDefinedField(JSObject* module)
+JS::GetModulePrivate(JSObject* module)
 {
-    return module->as<ModuleObject>().hostDefinedField();
+    return module->as<ModuleObject>().scriptSourceObject()->getPrivate();
+}
+
+JS_PUBLIC_API(void)
+JS::SetScriptPrivate(JSScript* script, const JS::Value& value)
+{
+    script->scriptSourceUnwrap().setPrivate(value);
+}
+
+JS_PUBLIC_API(JS::Value)
+JS::GetScriptPrivate(JSScript* script)
+{
+    return script->scriptSourceUnwrap().getPrivate();
 }
 
 JS_PUBLIC_API(bool)

js/src/jsapi.h

@@ -4324,7 +4324,7 @@ extern JS_PUBLIC_API(bool)
 Evaluate(JSContext* cx, const ReadOnlyCompileOptions& options,
          const char* filename, JS::MutableHandleValue rval);
 
-using ModuleResolveHook = JSObject* (*)(JSContext*, HandleObject, HandleString);
+using ModuleResolveHook = JSObject* (*)(JSContext*, HandleValue, HandleString);
 
 /**
  * Get the HostResolveImportedModule hook for the runtime.
@@ -4347,17 +4347,30 @@ CompileModule(JSContext* cx, const ReadOnlyCompileOptions& options,
               SourceBufferHolder& srcBuf, JS::MutableHandleObject moduleRecord);
 
 /**
- * Set the [[HostDefined]] field of a source text module record to the given
+ * Set a private value associated with a source text module record.
- * value.
  */
 extern JS_PUBLIC_API(void)
-SetModuleHostDefinedField(JSObject* module, const JS::Value& value);
+SetModulePrivate(JSObject* module, const JS::Value& value);
 
 /**
- * Get the [[HostDefined]] field of a source text module record.
+ * Get the private value associated with a source text module record.
  */
 extern JS_PUBLIC_API(JS::Value)
-GetModuleHostDefinedField(JSObject* module);
+GetModulePrivate(JSObject* module);
+
+/**
+ * Set a private value associated with a script. Note that this value is shared
+ * by all nested scripts compiled from a single source file.
+ */
+extern JS_PUBLIC_API(void)
+SetScriptPrivate(JSScript* script, const JS::Value& value);
+
+/**
+ * Get the private value associated with a script. Note that this value is
+ * shared by all nested scripts compiled from a single source file.
+ */
+extern JS_PUBLIC_API(JS::Value)
+GetScriptPrivate(JSScript* script);
 
 /*
  * Perform the ModuleInstantiate operation on the given source text module

js/src/jsscript.h

@@ -638,12 +638,22 @@ class ScriptSourceObject : public NativeObject
         return static_cast<JSScript*>(untyped);
     }
 
+    void setPrivate(const Value& value) {
+        setReservedSlot(PRIVATE_SLOT, value);
+    }
+    Value getPrivate() const {
+        return getReservedSlot(PRIVATE_SLOT);
+    }
+
   private:
-    static const uint32_t SOURCE_SLOT = 0;
+    enum {
-    static const uint32_t ELEMENT_SLOT = 1;
+        SOURCE_SLOT = 0,
-    static const uint32_t ELEMENT_PROPERTY_SLOT = 2;
+        ELEMENT_SLOT,
-    static const uint32_t INTRODUCTION_SCRIPT_SLOT = 3;
+        ELEMENT_PROPERTY_SLOT,
-    static const uint32_t RESERVED_SLOTS = 4;
+        INTRODUCTION_SCRIPT_SLOT,
+        PRIVATE_SLOT,
+        RESERVED_SLOTS
+    };
 };
 
 enum GeneratorKind { NotGenerator, LegacyGenerator, StarGenerator };

js/src/shell/js.cpp

@@ -4035,12 +4035,12 @@ SetModuleResolveHook(JSContext* cx, unsigned argc, Value* vp)
 }
 
 static JSObject*
-CallModuleResolveHook(JSContext* cx, HandleObject module, HandleString specifier)
+CallModuleResolveHook(JSContext* cx, HandleValue referencingPrivate, HandleString specifier)
 {
     ShellContext* sc = GetShellContext(cx);
 
     JS::AutoValueArray<2> args(cx);
-    args[0].setObject(*module);
+    args[0].set(referencingPrivate);
     args[1].setString(specifier);
 
     RootedValue result(cx);
@@ -4055,6 +4055,53 @@ CallModuleResolveHook(JSContext* cx, HandleObject module, HandleString specifier
     return &result.toObject();
 }
 
+static bool
+ReportArgumentTypeError(JSContext* cx, HandleValue value, const char* expected)
+{
+    const char* typeName = InformalValueTypeName(value);
+    JS_ReportErrorASCII(cx, "Expected %s, got %s", expected, typeName);
+    return false;
+}
+
+static bool
+ShellSetModulePrivate(JSContext* cx, unsigned argc, Value* vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+
+    if (args.length() != 2) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_MORE_ARGS_NEEDED,
+                                  "setModulePrivate", "0", "s");
+        return false;
+    }
+
+    if (!args[0].isObject() || !args[0].toObject().is<ModuleObject>()) {
+        return ReportArgumentTypeError(cx, args[0], "module object");
+    }
+
+    JS::SetModulePrivate(&args[0].toObject(), args[1]);
+    args.rval().setUndefined();
+    return true;
+}
+
+static bool
+ShellGetModulePrivate(JSContext* cx, unsigned argc, Value* vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+
+    if (args.length() != 1) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_MORE_ARGS_NEEDED,
+                                  "getModulePrivate", "0", "s");
+        return false;
+    }
+
+    if (!args[0].isObject() || !args[0].toObject().is<ModuleObject>()) {
+        return ReportArgumentTypeError(cx, args[0], "module object");
+    }
+
+    args.rval().set(JS::GetModulePrivate(&args[0].toObject()));
+    return true;
+}
+
 static bool
 GetModuleLoadPath(JSContext* cx, unsigned argc, Value* vp)
 {
@@ -5923,6 +5970,14 @@ static const JSFunctionSpecWithHelp shell_functions[] = {
 "  This hook is used to look up a previously loaded module object.  It should\n"
 "  be implemented by the module loader."),
 
+    JS_FN_HELP("setModulePrivate", ShellSetModulePrivate, 2, 0,
+"setModulePrivate(scriptObject, privateValue)",
+"  Associate a private value with a module object.\n"),
+
+    JS_FN_HELP("getModulePrivate", ShellGetModulePrivate, 2, 0,
+"getModulePrivate(scriptObject)",
+"  Get the private value associated with a module object.\n"),
+
     JS_FN_HELP("getModuleLoadPath", GetModuleLoadPath, 0, 0,
 "getModuleLoadPath()",
 "  Return any --module-load-path argument passed to the shell.  Used by the\n"

js/src/vm/SelfHosting.cpp

@@ -2006,7 +2006,8 @@ intrinsic_HostResolveImportedModule(JSContext* cx, unsigned argc, Value* vp)
     }
 
     RootedObject result(cx);
-    result = moduleResolveHook(cx, module, specifier);
+    RootedValue referencingPrivate(cx, JS::GetModulePrivate(module));
+    result = moduleResolveHook(cx, referencingPrivate, specifier);
     if (!result)
         return false;