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"
#include "nsGlobalWindow.h"
bool
nsJSUtils::GetCallingLocation(JSContext* aContext, const char* *aFilename,
uint32_t* aLineno)
{
JS::AutoFilename filename;
unsigned lineno = 0;
if (!JS::DescribeScriptedCaller(aContext, &filename, &lineno)) {
return false;
}
*aFilename = filename.get();
*aLineno = lineno;
return true;
}
nsIScriptGlobalObject *
nsJSUtils::GetStaticScriptGlobal(JSObject* aObj)
{
if (!aObj)
return nullptr;
return xpc::WindowGlobalOrNull(aObj);
}
nsIScriptContext *
nsJSUtils::GetStaticScriptContext(JSObject* aObj)
{
nsIScriptGlobalObject *nativeGlobal = GetStaticScriptGlobal(aObj);
if (!nativeGlobal)
return nullptr;
return nativeGlobal->GetScriptContext();
}
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);
{
// JS_SaveFrameChain set the compartment of aContext to null, so we need
// to enter a compartment. The question is, which one? We don't want to
// enter the original compartment of aContext (or the compartment of the
// current exception on aContext, for that matter) because when we
// JS_ReportPendingException the JS engine can try to duck-type the
// exception and produce a JSErrorReport. It will then pass that
// JSErrorReport to the error reporter on aContext, which might expose
// information from it to script via onerror handlers. So it's very
// important that the duck typing happen in the same compartment as the
// onerror handler. In practice, that's the compartment of the window (or
// otherwise default global) of aContext, so use that here.
nsIScriptContext* scx = GetScriptContextFromJSContext(aContext);
JS::Rooted<JSObject*> scope(aContext);
scope = scx ? scx->GetWindowProxy() : nullptr;
if (!scope) {
// The SafeJSContext has no default object associated with it.
MOZ_ASSERT(NS_IsMainThread());
MOZ_ASSERT(aContext == nsContentUtils::GetSafeJSContext());
scope = xpc::UnprivilegedJunkScope(); // Usage approved by bholley
}
JSAutoCompartment ac(aContext, scope);
JS_ReportPendingException(aContext);
}
if (saved) {
JS_RestoreFrameChain(aContext);
}
}
}
nsresult
nsJSUtils::CompileFunction(JSContext* aCx,
JS::Handle<JSObject*> 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());
// Do the junk Gecko is supposed to do before calling into JSAPI.
if (aTarget) {
JS::ExposeObjectToActiveJS(aTarget);
}
// Compile.
JS::Rooted<JSFunction*> fun(aCx);
if (!JS::CompileFunction(aCx, aTarget, aOptions,
PromiseFlatCString(aName).get(),
aArgCount, aArgArray,
PromiseFlatString(aBody).get(),
aBody.Length(), &fun))
{
ReportPendingException(aCx);
return NS_ERROR_FAILURE;
}
*aFunctionObject = JS_GetFunctionObject(fun);
return NS_OK;
}
nsresult
nsJSUtils::EvaluateString(JSContext* aCx,
const nsAString& aScript,
JS::Handle<JSObject*> aScopeObject,
JS::CompileOptions& aCompileOptions,
const EvaluateOptions& aEvaluateOptions,
JS::MutableHandle<JS::Value> aRetValue,
void **aOffThreadToken)
{
const nsPromiseFlatString& flatScript = PromiseFlatString(aScript);
JS::SourceBufferHolder srcBuf(flatScript.get(), aScript.Length(),
JS::SourceBufferHolder::NoOwnership);
return EvaluateString(aCx, srcBuf, aScopeObject, aCompileOptions,
aEvaluateOptions, aRetValue, aOffThreadToken);
}
nsresult
nsJSUtils::EvaluateString(JSContext* aCx,
JS::SourceBufferHolder& aSrcBuf,
JS::Handle<JSObject*> aScopeObject,
JS::CompileOptions& aCompileOptions,
const EvaluateOptions& aEvaluateOptions,
JS::MutableHandle<JS::Value> aRetValue,
void **aOffThreadToken)
{
PROFILER_LABEL("nsJSUtils", "EvaluateString",
js::ProfileEntry::Category::JS);
MOZ_ASSERT_IF(aCompileOptions.versionSet,
aCompileOptions.version != JSVERSION_UNKNOWN);
MOZ_ASSERT_IF(aEvaluateOptions.coerceToString, aEvaluateOptions.needResult);
MOZ_ASSERT_IF(!aEvaluateOptions.reportUncaught, aEvaluateOptions.needResult);
MOZ_ASSERT(aCx == nsContentUtils::GetCurrentJSContext());
MOZ_ASSERT(aSrcBuf.get());
// 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 can do this by calling the other overload of
// EvaluateString() which calls this function with aEvaluateOptions.needResult
// set to false.
aRetValue.setUndefined();
JS::ExposeObjectToActiveJS(aScopeObject);
nsAutoMicroTask mt;
nsresult rv = NS_OK;
bool ok = false;
nsIScriptSecurityManager* ssm = nsContentUtils::GetSecurityManager();
NS_ENSURE_TRUE(ssm->ScriptAllowed(js::GetGlobalForObjectCrossCompartment(aScopeObject)), NS_OK);
mozilla::Maybe<AutoDontReportUncaught> dontReport;
if (!aEvaluateOptions.reportUncaught) {
// We need to prevent AutoLastFrameCheck from reporting and clearing
// any pending exceptions.
dontReport.emplace(aCx);
}
// Scope the JSAutoCompartment so that we can later wrap the return value
// into the caller's cx.
{
JSAutoCompartment ac(aCx, aScopeObject);
JS::Rooted<JSObject*> rootedScope(aCx, aScopeObject);
if (aOffThreadToken) {
JS::Rooted<JSScript*>
script(aCx, JS::FinishOffThreadScript(aCx, JS_GetRuntime(aCx), *aOffThreadToken));
*aOffThreadToken = nullptr; // Mark the token as having been finished.
if (script) {
if (aEvaluateOptions.needResult) {
ok = JS_ExecuteScript(aCx, rootedScope, script, aRetValue);
} else {
ok = JS_ExecuteScript(aCx, rootedScope, script);
}
} else {
ok = false;
}
} else {
if (aEvaluateOptions.needResult) {
ok = JS::Evaluate(aCx, rootedScope, aCompileOptions,
aSrcBuf, aRetValue);
} else {
ok = JS::Evaluate(aCx, rootedScope, aCompileOptions,
aSrcBuf);
}
}
if (ok && aEvaluateOptions.coerceToString && !aRetValue.isUndefined()) {
JS::Rooted<JS::Value> value(aCx, aRetValue);
JSString* str = JS::ToString(aCx, value);
ok = !!str;
aRetValue.set(ok ? JS::StringValue(str) : JS::UndefinedValue());
}
}
if (!ok) {
if (aEvaluateOptions.reportUncaught) {
ReportPendingException(aCx);
if (aEvaluateOptions.needResult) {
aRetValue.setUndefined();
}
} else {
rv = JS_IsExceptionPending(aCx) ? NS_ERROR_FAILURE
: NS_ERROR_OUT_OF_MEMORY;
JS::Rooted<JS::Value> exn(aCx);
JS_GetPendingException(aCx, &exn);
if (aEvaluateOptions.needResult) {
aRetValue.set(exn);
}
JS_ClearPendingException(aCx);
}
}
// Wrap the return value into whatever compartment aCx was in.
if (aEvaluateOptions.needResult) {
JS::Rooted<JS::Value> v(aCx, aRetValue);
if (!JS_WrapValue(aCx, &v)) {
return NS_ERROR_OUT_OF_MEMORY;
}
aRetValue.set(v);
}
return rv;
}
nsresult
nsJSUtils::EvaluateString(JSContext* aCx,
const nsAString& aScript,
JS::Handle<JSObject*> aScopeObject,
JS::CompileOptions& aCompileOptions,
void **aOffThreadToken)
{
EvaluateOptions options;
options.setNeedResult(false);
JS::RootedValue unused(aCx);
return EvaluateString(aCx, aScript, aScopeObject, aCompileOptions,
options, &unused, aOffThreadToken);
}
nsresult
nsJSUtils::EvaluateString(JSContext* aCx,
JS::SourceBufferHolder& aSrcBuf,
JS::Handle<JSObject*> aScopeObject,
JS::CompileOptions& aCompileOptions,
void **aOffThreadToken)
{
EvaluateOptions options;
options.setNeedResult(false);
JS::RootedValue unused(aCx);
return EvaluateString(aCx, aSrcBuf, aScopeObject, aCompileOptions,
options, &unused, aOffThreadToken);
}
//
// 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);
return scx ? scx->GetWindowProxy() : nullptr;
}