From 22f300f7c431bbf4de20437d2ebd7bff38284efb Mon Sep 17 00:00:00 2001
From: Jon Coppeard <jcoppeard@mozilla.com>
Date: Thu, 27 Aug 2020 09:14:33 +0000
Subject: Issue #618 - Add JS API to associate scripts with DOM elements after
 compilation

Ref BZ 1342416
---
 js/src/jsapi.cpp    | 11 +++++++++++
 js/src/jsapi.h      |  9 +++++++++
 js/src/jsscript.cpp | 35 +++++++++++++++++++++++------------
 js/src/jsscript.h   |  2 ++
 4 files changed, 45 insertions(+), 12 deletions(-)

diff --git a/js/src/jsapi.cpp b/js/src/jsapi.cpp
index 69a3ba2ac2..dd1b254864 100644
--- a/js/src/jsapi.cpp
+++ b/js/src/jsapi.cpp
@@ -4432,6 +4432,17 @@ JS::CompileFunction(JSContext* cx, AutoObjectVector& envChain,
                            chars.get(), length, fun);
 }
 
+JS_PUBLIC_API(bool)
+JS::InitScriptSourceElement(JSContext* cx, HandleScript script,
+                            HandleObject element, HandleString elementAttrName)
+{
+    MOZ_ASSERT(cx);
+    MOZ_ASSERT(CurrentThreadCanAccessRuntime(cx->runtime()));
+
+    RootedScriptSource sso(cx, &script->sourceObject()->as<ScriptSourceObject>());
+    return ScriptSourceObject::initElementProperties(cx, sso, element, elementAttrName);
+}
+
 JS_PUBLIC_API(JSString*)
 JS_DecompileScript(JSContext* cx, HandleScript script, const char* name, unsigned indent)
 {
diff --git a/js/src/jsapi.h b/js/src/jsapi.h
index 5cdfd958e7..476bc03b9b 100644
--- a/js/src/jsapi.h
+++ b/js/src/jsapi.h
@@ -4212,6 +4212,15 @@ CompileFunction(JSContext* cx, AutoObjectVector& envChain,
                 const char* name, unsigned nargs, const char* const* argnames,
                 const char* bytes, size_t length, JS::MutableHandleFunction fun);
 
+/*
+ * Associate an element wrapper and attribute name with a previously compiled
+ * script, for debugging purposes. Calling this function is optional, but should
+ * be done before script execution if it is required.
+ */
+extern JS_PUBLIC_API(bool)
+InitScriptSourceElement(JSContext* cx, HandleScript script,
+                        HandleObject element, HandleString elementAttrName = nullptr);
+
 } /* namespace JS */
 
 extern JS_PUBLIC_API(JSString*)
diff --git a/js/src/jsscript.cpp b/js/src/jsscript.cpp
index bdd411d043..ba2e540e41 100644
--- a/js/src/jsscript.cpp
+++ b/js/src/jsscript.cpp
@@ -1407,19 +1407,10 @@ ScriptSourceObject::initFromOptions(JSContext* cx, HandleScriptSource source,
     MOZ_ASSERT(source->getReservedSlot(ELEMENT_PROPERTY_SLOT).isMagic(JS_GENERIC_MAGIC));
     MOZ_ASSERT(source->getReservedSlot(INTRODUCTION_SCRIPT_SLOT).isMagic(JS_GENERIC_MAGIC));
 
-    RootedValue element(cx, ObjectOrNullValue(options.element()));
-    if (!cx->compartment()->wrap(cx, &element))
+    RootedObject element(cx, options.element());
+    RootedString elementAttributeName(cx, options.elementAttributeName());
+    if (!initElementProperties(cx, source, element, elementAttributeName))
         return false;
-    source->setReservedSlot(ELEMENT_SLOT, element);
-
-    RootedValue elementAttributeName(cx);
-    if (options.elementAttributeName())
-        elementAttributeName = StringValue(options.elementAttributeName());
-    else
-        elementAttributeName = UndefinedValue();
-    if (!cx->compartment()->wrap(cx, &elementAttributeName))
-        return false;
-    source->setReservedSlot(ELEMENT_PROPERTY_SLOT, elementAttributeName);
 
     // There is no equivalent of cross-compartment wrappers for scripts. If the
     // introduction script and ScriptSourceObject are in different compartments,
@@ -1437,6 +1428,26 @@ ScriptSourceObject::initFromOptions(JSContext* cx, HandleScriptSource source,
     return true;
 }
 
+bool
+ScriptSourceObject::initElementProperties(JSContext* cx, HandleScriptSource source,
+                                          HandleObject element, HandleString elementAttrName)
+{
+    RootedValue elementValue(cx, ObjectOrNullValue(element));
+    if (!cx->compartment()->wrap(cx, &elementValue))
+        return false;
+
+    RootedValue nameValue(cx);
+    if (elementAttrName)
+        nameValue = StringValue(elementAttrName);
+    if (!cx->compartment()->wrap(cx, &nameValue))
+        return false;
+
+    source->setReservedSlot(ELEMENT_SLOT, elementValue);
+    source->setReservedSlot(ELEMENT_PROPERTY_SLOT, nameValue);
+
+    return true;
+}
+
 /* static */ bool
 JSScript::loadSource(JSContext* cx, ScriptSource* ss, bool* worked)
 {
diff --git a/js/src/jsscript.h b/js/src/jsscript.h
index c19fbfc71d..74803c0f68 100644
--- a/js/src/jsscript.h
+++ b/js/src/jsscript.h
@@ -620,6 +620,8 @@ class ScriptSourceObject : public NativeObject
     // are provided by |options|, re-wrapping as necessary.
     static bool initFromOptions(JSContext* cx, HandleScriptSource source,
                                 const ReadOnlyCompileOptions& options);
+    static bool initElementProperties(JSContext* cx, HandleScriptSource source,
+                                      HandleObject element, HandleString elementAttrName);
 
     ScriptSource* source() const {
         return static_cast<ScriptSource*>(getReservedSlot(SOURCE_SLOT).toPrivate());
-- 
cgit v1.2.3