gecko-dev/dom/base/nsJSUtils.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 sw=2 et tw=78: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
* This is not a generated file. It contains common utility functions
* invoked from the JavaScript code generated from IDL interfaces.
* The goal of the utility functions is to cut down on the size of
* the generated code itself.
*/
#include "nsJSUtils.h"
#include "jsapi.h"
#include "js/OldDebugAPI.h"
#include "jsfriendapi.h"
#include "nsIScriptContext.h"
#include "nsIScriptGlobalObject.h"
#include "nsIXPConnect.h"
#include "nsCOMPtr.h"
#include "nsIScriptSecurityManager.h"
#include "nsPIDOMWindow.h"
#include "GeckoProfiler.h"
#include "nsDOMJSUtils.h" // for GetScriptContextFromJSContext
#include "nsJSPrincipals.h"
#include "xpcpublic.h"
#include "nsContentUtils.h"
bool
nsJSUtils::GetCallingLocation(JSContext* aContext, const char* *aFilename,
uint32_t* aLineno)
{
JS::RootedScript script(aContext);
unsigned lineno = 0;
if (!JS_DescribeScriptedCaller(aContext, &script, &lineno)) {
return false;
}
*aFilename = ::JS_GetScriptFilename(aContext, script);
*aLineno = lineno;
return true;
}
nsIScriptGlobalObject *
nsJSUtils::GetStaticScriptGlobal(JSObject* aObj)
{
const JSClass* clazz;
JSObject* glob = aObj; // starting point for search
if (!glob)
return nullptr;
glob = js::GetGlobalForObjectCrossCompartment(glob);
NS_ABORT_IF_FALSE(glob, "Infallible returns null");
clazz = JS_GetClass(glob);
// Whenever we end up with globals that are JSCLASS_IS_DOMJSCLASS
// and have an nsISupports DOM object, we will need to modify this
// check here.
MOZ_ASSERT(!(clazz->flags & JSCLASS_IS_DOMJSCLASS));
nsISupports* supports;
if (!(clazz->flags & JSCLASS_HAS_PRIVATE) ||
!(clazz->flags & JSCLASS_PRIVATE_IS_NSISUPPORTS) ||
!(supports = (nsISupports*)::JS_GetPrivate(glob))) {
return nullptr;
}
// We might either have a window directly (e.g. if the global is a
// sandbox whose script object principal pointer is a window), or an
// XPCWrappedNative for a window. We could also have other
// sandbox-related script object principals, but we can't do much
// about those short of trying to walk the proto chain of |glob|
// looking for a window or something.
nsCOMPtr<nsIScriptGlobalObject> sgo(do_QueryInterface(supports));
if (!sgo) {
nsCOMPtr<nsIXPConnectWrappedNative> wrapper(do_QueryInterface(supports));
if (!wrapper) {
return nullptr;
}
sgo = do_QueryWrappedNative(wrapper);
}
// We're returning a pointer to something that's about to be
// released, but that's ok here.
return sgo;
}
nsIScriptContext *
nsJSUtils::GetStaticScriptContext(JSObject* aObj)
{
nsIScriptGlobalObject *nativeGlobal = GetStaticScriptGlobal(aObj);
if (!nativeGlobal)
return nullptr;
return nativeGlobal->GetScriptContext();
}
nsIScriptGlobalObject *
nsJSUtils::GetDynamicScriptGlobal(JSContext* aContext)
{
nsIScriptContext *scriptCX = GetDynamicScriptContext(aContext);
if (!scriptCX)
return nullptr;
return scriptCX->GetGlobalObject();
}
nsIScriptContext *
nsJSUtils::GetDynamicScriptContext(JSContext *aContext)
{
return GetScriptContextFromJSContext(aContext);
}
uint64_t
nsJSUtils::GetCurrentlyRunningCodeInnerWindowID(JSContext *aContext)
{
if (!aContext)
return 0;
uint64_t innerWindowID = 0;
JSObject *jsGlobal = JS::CurrentGlobalOrNull(aContext);
if (jsGlobal) {
nsIScriptGlobalObject *scriptGlobal = GetStaticScriptGlobal(jsGlobal);
if (scriptGlobal) {
nsCOMPtr<nsPIDOMWindow> win = do_QueryInterface(scriptGlobal);
if (win)
innerWindowID = win->WindowID();
}
}
return innerWindowID;
}
void
nsJSUtils::ReportPendingException(JSContext *aContext)
{
if (JS_IsExceptionPending(aContext)) {
bool saved = JS_SaveFrameChain(aContext);
{
nsIScriptContext* scx = GetScriptContextFromJSContext(aContext);
JS::Rooted<JSObject*> scope(aContext);
scope = scx ? scx->GetWindowProxy()
: js::DefaultObjectForContextOrNull(aContext);
JSAutoCompartment ac(aContext, scope);
JS_ReportPendingException(aContext);
}
if (saved) {
JS_RestoreFrameChain(aContext);
}
}
}
nsresult
nsJSUtils::CompileFunction(JSContext* aCx,
JS::HandleObject aTarget,
JS::CompileOptions& aOptions,
const nsACString& aName,
uint32_t aArgCount,
const char** aArgArray,
const nsAString& aBody,
JSObject** aFunctionObject)
{
MOZ_ASSERT(js::GetEnterCompartmentDepth(aCx) > 0);
MOZ_ASSERT_IF(aTarget, js::IsObjectInContextCompartment(aTarget, aCx));
MOZ_ASSERT_IF(aOptions.versionSet, aOptions.version != JSVERSION_UNKNOWN);
mozilla::DebugOnly<nsIScriptContext*> ctx = GetScriptContextFromJSContext(aCx);
MOZ_ASSERT_IF(ctx, ctx->IsContextInitialized());
// Since aTarget and aCx are same-compartment, there should be no distinction
// between the object principal and the cx principal.
// However, aTarget may be null in the wacky aShared case. So use the cx.
JSPrincipals* p = JS_GetCompartmentPrincipals(js::GetContextCompartment(aCx));
aOptions.setPrincipals(p);
// Do the junk Gecko is supposed to do before calling into JSAPI.
if (aTarget) {
JS::ExposeObjectToActiveJS(aTarget);
}
// Compile.
JSFunction* fun = JS::CompileFunction(aCx, aTarget, aOptions,
PromiseFlatCString(aName).get(),
aArgCount, aArgArray,
PromiseFlatString(aBody).get(),
aBody.Length());
if (!fun) {
ReportPendingException(aCx);
return NS_ERROR_FAILURE;
}
*aFunctionObject = JS_GetFunctionObject(fun);
return NS_OK;
}
class MOZ_STACK_CLASS AutoDontReportUncaught {
JSContext* mContext;
bool mWasSet;
public:
AutoDontReportUncaught(JSContext* aContext) : mContext(aContext) {
MOZ_ASSERT(aContext);
uint32_t oldOptions = JS_GetOptions(mContext);
mWasSet = oldOptions & JSOPTION_DONT_REPORT_UNCAUGHT;
if (!mWasSet) {
JS_SetOptions(mContext, oldOptions | JSOPTION_DONT_REPORT_UNCAUGHT);
}
}
~AutoDontReportUncaught() {
if (!mWasSet) {
JS_SetOptions(mContext,
JS_GetOptions(mContext) & ~JSOPTION_DONT_REPORT_UNCAUGHT);
}
}
};
nsresult
nsJSUtils::EvaluateString(JSContext* aCx,
const nsAString& aScript,
JS::Handle<JSObject*> aScopeObject,
JS::CompileOptions& aCompileOptions,
EvaluateOptions& aEvaluateOptions,
JS::Value* aRetValue,
void **aOffThreadToken)
{
PROFILER_LABEL("JS", "EvaluateString");
MOZ_ASSERT_IF(aCompileOptions.versionSet,
aCompileOptions.version != JSVERSION_UNKNOWN);
MOZ_ASSERT_IF(aEvaluateOptions.coerceToString, aRetValue);
MOZ_ASSERT_IF(!aEvaluateOptions.reportUncaught, aRetValue);
MOZ_ASSERT(aCx == nsContentUtils::GetCurrentJSContext());
// Unfortunately, the JS engine actually compiles scripts with a return value
// in a different, less efficient way. Furthermore, it can't JIT them in many
// cases. So we need to be explicitly told whether the caller cares about the
// return value. Callers use null to indicate they don't care.
if (aRetValue) {
*aRetValue = JSVAL_VOID;
}
JS::ExposeObjectToActiveJS(aScopeObject);
nsAutoMicroTask mt;
JSPrincipals* p = JS_GetCompartmentPrincipals(js::GetObjectCompartment(aScopeObject));
aCompileOptions.setPrincipals(p);
bool ok = false;
nsresult rv = nsContentUtils::GetSecurityManager()->
CanExecuteScripts(aCx, nsJSPrincipals::get(p), &ok);
NS_ENSURE_SUCCESS(rv, rv);
NS_ENSURE_TRUE(ok, NS_OK);
mozilla::Maybe<AutoDontReportUncaught> dontReport;
if (!aEvaluateOptions.reportUncaught) {
// We need to prevent AutoLastFrameCheck from reporting and clearing
// any pending exceptions.
dontReport.construct(aCx);
}
// Scope the JSAutoCompartment so that we can later wrap the return value
// into the caller's cx.
{
JSAutoCompartment ac(aCx, aScopeObject);
JS::RootedObject rootedScope(aCx, aScopeObject);
if (aOffThreadToken) {
JSScript *script = JS::FinishOffThreadScript(aCx, JS_GetRuntime(aCx), *aOffThreadToken);
*aOffThreadToken = nullptr; // Mark the token as having been finished.
if (script) {
ok = JS_ExecuteScript(aCx, rootedScope, script, aRetValue);
} else {
ok = false;
}
} else {
ok = JS::Evaluate(aCx, rootedScope, aCompileOptions,
PromiseFlatString(aScript).get(),
aScript.Length(), aRetValue);
}
if (ok && aEvaluateOptions.coerceToString && !aRetValue->isUndefined()) {
JSString* str = JS_ValueToString(aCx, *aRetValue);
ok = !!str;
*aRetValue = ok ? JS::StringValue(str) : JS::UndefinedValue();
}
}
if (!ok) {
if (aEvaluateOptions.reportUncaught) {
ReportPendingException(aCx);
if (aRetValue) {
*aRetValue = JS::UndefinedValue();
}
} else {
rv = JS_IsExceptionPending(aCx) ? NS_ERROR_FAILURE
: NS_ERROR_OUT_OF_MEMORY;
JS::RootedValue exn(aCx);
JS_GetPendingException(aCx, &exn);
if (aRetValue) {
*aRetValue = exn;
}
JS_ClearPendingException(aCx);
}
}
// Wrap the return value into whatever compartment aCx was in.
if (aRetValue && !JS_WrapValue(aCx, aRetValue))
return NS_ERROR_OUT_OF_MEMORY;
return rv;
}
//
// nsDOMJSUtils.h
//
JSObject* GetDefaultScopeFromJSContext(JSContext *cx)
{
// DOM JSContexts don't store their default compartment object on
// the cx, so in those cases we need to fetch it via the scx
// instead.
nsIScriptContext *scx = GetScriptContextFromJSContext(cx);
if (scx) {
return scx->GetWindowProxy();
}
return js::DefaultObjectForContextOrNull(cx);
}