Bug 1140435 - Part 2 - Allow JS code to provide an async stack when calling a function. r=bz

dom/bindings/Exceptions.cpp

@@ -311,6 +311,7 @@ public:
   NS_IMETHOD GetAsyncCaller(nsIStackFrame** aAsyncCaller) MOZ_OVERRIDE;
   NS_IMETHOD GetCaller(nsIStackFrame** aCaller) MOZ_OVERRIDE;
   NS_IMETHOD GetFormattedStack(nsAString& aStack) MOZ_OVERRIDE;
+  NS_IMETHOD GetNativeSavedFrame(JS::MutableHandle<JS::Value> aSavedFrame) MOZ_OVERRIDE;
 
 protected:
   virtual bool IsJSFrame() const MOZ_OVERRIDE {
@@ -750,6 +751,19 @@ NS_IMETHODIMP StackFrame::GetFormattedStack(nsAString& aStack)
   return NS_OK;
 }
 
+/* readonly attribute jsval nativeSavedFrame; */
+NS_IMETHODIMP JSStackFrame::GetNativeSavedFrame(JS::MutableHandle<JS::Value> aSavedFrame)
+{
+  aSavedFrame.setObjectOrNull(mStack);
+  return NS_OK;
+}
+
+NS_IMETHODIMP StackFrame::GetNativeSavedFrame(JS::MutableHandle<JS::Value> aSavedFrame)
+{
+  aSavedFrame.setNull();
+  return NS_OK;
+}
+
 /* AUTF8String toString (); */
 NS_IMETHODIMP StackFrame::ToString(nsACString& _retval)
 {

js/xpconnect/idl/xpccomponents.idl

@@ -122,7 +122,7 @@ interface ScheduledGCCallback : nsISupports
 /**
 * interface of Components.utils
 */
-[scriptable, uuid(2617a800-63c1-11e4-9803-0800200c9a66)]
+[scriptable, uuid(0354f8b4-08c6-4074-a466-2b6524b64ca3)]
 interface nsIXPCComponents_Utils : nsISupports
 {
 
@@ -361,6 +361,20 @@ interface nsIXPCComponents_Utils : nsISupports
     [implicit_jscontext]
     jsval getJSTestingFunctions();
 
+    /*
+     * To be called from JS only.
+     *
+     * Call 'function', using the provided stack as the async stack responsible
+     * for the call, and propagate its return value or the exception it throws.
+     * The function is called with no arguments, and 'this' is 'undefined'.
+     *
+     * The code in the function will see the given stack frame as the
+     * asyncCaller of its own stack frame, instead of the current caller.
+     */
+    [implicit_jscontext]
+    jsval callFunctionWithAsyncStack(in jsval function, in nsIStackFrame stack,
+                                     in AString asyncCause);
+
     /*
      * To be called from JS only.
      *

js/xpconnect/src/XPCComponents.cpp

@@ -2901,6 +2901,47 @@ nsXPCComponents_Utils::GetJSTestingFunctions(JSContext *cx,
     return NS_OK;
 }
 
+/* jsval callFunctionWithStack(in jsval function, in nsIStackFrame stack,
+                               in AString asyncCause); */
+NS_IMETHODIMP
+nsXPCComponents_Utils::CallFunctionWithAsyncStack(HandleValue function,
+                                                  nsIStackFrame *stack,
+                                                  const nsAString &asyncCause,
+                                                  JSContext *cx,
+                                                  MutableHandleValue retval)
+{
+    nsresult rv;
+
+    if (!stack || asyncCause.IsEmpty()) {
+        return NS_ERROR_INVALID_ARG;
+    }
+
+    JS::Rooted<JS::Value> asyncStack(cx);
+    rv = stack->GetNativeSavedFrame(&asyncStack);
+    if (NS_FAILED(rv))
+        return rv;
+    if (!asyncStack.isObject()) {
+        JS_ReportError(cx, "Must use a native JavaScript stack frame");
+        return NS_ERROR_INVALID_ARG;
+    }
+
+    JS::Rooted<JSObject*> asyncStackObj(cx, &asyncStack.toObject());
+    JS::Rooted<JSString*> asyncCauseString(cx, JS_NewUCStringCopyN(cx, asyncCause.BeginReading(),
+                                                                       asyncCause.Length()));
+    if (!asyncCauseString)
+        return NS_ERROR_OUT_OF_MEMORY;
+
+    JS::AutoSetAsyncStackForNewCalls sas(cx, asyncStackObj, asyncCauseString);
+
+    if (!JS_CallFunctionValue(cx, JS::NullPtr(), function,
+                              JS::HandleValueArray::empty(), retval))
+    {
+        return NS_ERROR_XPC_JAVASCRIPT_ERROR;
+    }
+
+    return NS_OK;
+}
+
 /* void getGlobalForObject(); */
 NS_IMETHODIMP
 nsXPCComponents_Utils::GetGlobalForObject(HandleValue object,

js/xpconnect/tests/unit/test_callFunctionWithAsyncStack.js

@@ -0,0 +1,23 @@
+function run_test() {
+  function getAsyncStack() {
+    return Components.stack;
+  }
+
+  // asyncCause may contain non-ASCII characters.
+  let testAsyncCause = "Tes" + String.fromCharCode(355) + "String";
+
+  Components.utils.callFunctionWithAsyncStack(function asyncCallback() {
+    let stack = Components.stack;
+
+    do_check_eq(stack.name, "asyncCallback");
+    do_check_eq(stack.caller.name, null);
+    do_check_eq(stack.asyncCause, null);
+
+    do_check_eq(stack.asyncCaller.name, "getAsyncStack");
+    do_check_eq(stack.asyncCaller.asyncCause, testAsyncCause);
+    do_check_eq(stack.asyncCaller.asyncCaller, null);
+
+    do_check_eq(stack.asyncCaller.caller.name, "run_test");
+    do_check_eq(stack.asyncCaller.caller.asyncCause, null);
+  }, getAsyncStack(), testAsyncCause);
+}

js/xpconnect/tests/unit/xpcshell.ini

@@ -55,6 +55,7 @@ support-files =
 [test_bug1081990.js]
 [test_bug1110546.js]
 [test_bug_442086.js]
+[test_callFunctionWithAsyncStack.js]
 [test_file.js]
 [test_blob.js]
 [test_blob2.js]

xpcom/base/nsIException.idl

@@ -10,7 +10,7 @@
 
 #include "nsISupports.idl"
 
-[scriptable, uuid(9787bc41-1ec9-4fe0-8b31-ffee5db6a893)]
+[scriptable, uuid(28bfb2a2-5ea6-4738-918b-049dc4d51f0b)]
 interface nsIStackFrame : nsISupports
 {
     // see nsIProgrammingLanguage for list of language consts
@@ -31,6 +31,10 @@ interface nsIStackFrame : nsISupports
     // Only works on JS-language stack frames.
     readonly attribute AString                 formattedStack;
 
+    // Returns the underlying SavedFrame object for native JavaScript stacks,
+    // or null if this is not a native JavaScript stack frame.
+    readonly attribute jsval                   nativeSavedFrame;
+
     AUTF8String toString();
 };