gecko/dom/bindings/BindingUtils.h

871 lines
23 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
/* vim: set ts=2 sw=2 et tw=79: */
/* 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/. */
#ifndef mozilla_dom_BindingUtils_h__
#define mozilla_dom_BindingUtils_h__
#include "mozilla/dom/DOMJSClass.h"
#include "mozilla/dom/workers/Workers.h"
#include "mozilla/ErrorResult.h"
#include "jsapi.h"
#include "jsfriendapi.h"
#include "jswrapper.h"
#include "nsIXPConnect.h"
#include "qsObjectHelper.h"
#include "xpcpublic.h"
#include "nsTraceRefcnt.h"
#include "nsWrapperCacheInlines.h"
// nsGlobalWindow implements nsWrapperCache, but doesn't always use it. Don't
// try to use it without fixing that first.
class nsGlobalWindow;
namespace mozilla {
namespace dom {
template<bool mainThread>
inline bool
Throw(JSContext* cx, nsresult rv)
{
using mozilla::dom::workers::exceptions::ThrowDOMExceptionForNSResult;
// XXX Introduce exception machinery.
if (mainThread) {
xpc::Throw(cx, rv);
} else {
if (!JS_IsExceptionPending(cx)) {
ThrowDOMExceptionForNSResult(cx, rv);
}
}
return false;
}
template<bool mainThread>
inline bool
ThrowMethodFailedWithDetails(JSContext* cx, const ErrorResult& rv,
const char* /* ifaceName */,
const char* /* memberName */)
{
return Throw<mainThread>(cx, rv.ErrorCode());
}
inline bool
IsDOMClass(const JSClass* clasp)
{
return clasp->flags & JSCLASS_IS_DOMJSCLASS;
}
inline bool
IsDOMClass(const js::Class* clasp)
{
return IsDOMClass(Jsvalify(clasp));
}
template <class T>
inline T*
UnwrapDOMObject(JSObject* obj)
{
MOZ_ASSERT(IsDOMClass(JS_GetClass(obj)));
JS::Value val = js::GetReservedSlot(obj, DOM_OBJECT_SLOT);
// XXXbz/khuey worker code tries to unwrap interface objects (which have
// nothing here). That needs to stop.
// XXX We don't null-check UnwrapObject's result; aren't we going to crash
// anyway?
if (val.isUndefined()) {
return NULL;
}
return static_cast<T*>(val.toPrivate());
}
// Some callers don't want to set an exception when unwrappin fails
// (for example, overload resolution uses unwrapping to tell what sort
// of thing it's looking at).
// U must be something that a T* can be assigned to (e.g. T* or an nsRefPtr<T>).
template <prototypes::ID PrototypeID, class T, typename U>
inline nsresult
UnwrapObject(JSContext* cx, JSObject* obj, U& value)
{
/* First check to see whether we have a DOM object */
JSClass* clasp = js::GetObjectJSClass(obj);
if (!IsDOMClass(clasp)) {
/* Maybe we have a security wrapper or outer window? */
if (!js::IsWrapper(obj)) {
/* Not a DOM object, not a wrapper, just bail */
return NS_ERROR_XPC_BAD_CONVERT_JS;
}
obj = xpc::Unwrap(cx, obj, false);
if (!obj) {
return NS_ERROR_XPC_SECURITY_MANAGER_VETO;
}
MOZ_ASSERT(!js::IsWrapper(obj));
clasp = js::GetObjectJSClass(obj);
if (!IsDOMClass(clasp)) {
/* We don't have a DOM object */
return NS_ERROR_XPC_BAD_CONVERT_JS;
}
}
MOZ_ASSERT(IsDOMClass(clasp));
/* This object is a DOM object. Double-check that it is safely
castable to T by checking whether it claims to inherit from the
class identified by protoID. */
DOMJSClass* domClass = DOMJSClass::FromJSClass(clasp);
if (domClass->mInterfaceChain[PrototypeTraits<PrototypeID>::Depth] ==
PrototypeID) {
value = UnwrapDOMObject<T>(obj);
return NS_OK;
}
/* It's the wrong sort of DOM object */
return NS_ERROR_XPC_BAD_CONVERT_JS;
}
inline bool
IsArrayLike(JSContext* cx, JSObject* obj)
{
MOZ_ASSERT(obj);
// For simplicity, check for security wrappers up front. In case we
// have a security wrapper, don't forget to enter the compartment of
// the underlying object after unwrapping.
JSAutoEnterCompartment ac;
if (js::IsWrapper(obj)) {
obj = xpc::Unwrap(cx, obj, false);
if (!obj) {
// Let's say it's not
return false;
}
if (!ac.enter(cx, obj)) {
return false;
}
}
// XXXbz need to detect platform objects (including listbinding
// ones) with indexGetters here!
return JS_IsArrayObject(cx, obj) || JS_IsTypedArrayObject(obj, cx);
}
inline bool
IsPlatformObject(JSContext* cx, JSObject* obj)
{
// XXXbz Should be treating list-binding objects as platform objects
// too? The one consumer so far wants non-array-like platform
// objects, so listbindings that have an indexGetter should test
// false from here. Maybe this function should have a different
// name?
MOZ_ASSERT(obj);
// Fast-path the common case
JSClass* clasp = js::GetObjectJSClass(obj);
if (IsDOMClass(clasp)) {
return true;
}
// Now for simplicity check for security wrappers before anything else
if (js::IsWrapper(obj)) {
obj = xpc::Unwrap(cx, obj, false);
if (!obj) {
// Let's say it's not
return false;
}
clasp = js::GetObjectJSClass(obj);
}
return IS_WRAPPER_CLASS(js::Valueify(clasp)) || IsDOMClass(clasp) ||
JS_IsArrayBufferObject(obj, cx);
}
// U must be something that a T* can be assigned to (e.g. T* or an nsRefPtr<T>).
template <class T, typename U>
inline nsresult
UnwrapObject(JSContext* cx, JSObject* obj, U& value)
{
return UnwrapObject<static_cast<prototypes::ID>(
PrototypeIDMap<T>::PrototypeID)>(cx, obj, value);
}
const size_t kProtoOrIfaceCacheCount =
prototypes::id::_ID_Count + constructors::id::_ID_Count;
inline void
AllocateProtoOrIfaceCache(JSObject* obj)
{
MOZ_ASSERT(js::GetObjectClass(obj)->flags & JSCLASS_DOM_GLOBAL);
MOZ_ASSERT(js::GetReservedSlot(obj, DOM_PROTOTYPE_SLOT).isUndefined());
// Important: The () at the end ensure zero-initialization
JSObject** protoOrIfaceArray = new JSObject*[kProtoOrIfaceCacheCount]();
js::SetReservedSlot(obj, DOM_PROTOTYPE_SLOT,
JS::PrivateValue(protoOrIfaceArray));
}
inline void
TraceProtoOrIfaceCache(JSTracer* trc, JSObject* obj)
{
MOZ_ASSERT(js::GetObjectClass(obj)->flags & JSCLASS_DOM_GLOBAL);
if (!HasProtoOrIfaceArray(obj))
return;
JSObject** protoOrIfaceArray = GetProtoOrIfaceArray(obj);
for (size_t i = 0; i < kProtoOrIfaceCacheCount; ++i) {
JSObject* proto = protoOrIfaceArray[i];
if (proto) {
JS_CALL_OBJECT_TRACER(trc, proto, "protoOrIfaceArray[i]");
}
}
}
inline void
DestroyProtoOrIfaceCache(JSObject* obj)
{
MOZ_ASSERT(js::GetObjectClass(obj)->flags & JSCLASS_DOM_GLOBAL);
JSObject** protoOrIfaceArray = GetProtoOrIfaceArray(obj);
delete [] protoOrIfaceArray;
}
struct ConstantSpec
{
const char* name;
JS::Value value;
};
/**
* Add constants to an object.
*/
bool
DefineConstants(JSContext* cx, JSObject* obj, ConstantSpec* cs);
template<typename T>
struct Prefable {
// A boolean indicating whether this set of specs is enabled
bool enabled;
// Array of specs, terminated in whatever way is customary for T.
// Null to indicate a end-of-array for Prefable, when such an
// indicator is needed.
T* specs;
};
/*
* Create a DOM interface object (if constructorClass is non-null) and/or a
* DOM interface prototype object (if protoClass is non-null).
*
* global is used as the parent of the interface object and the interface
* prototype object
* receiver is the object on which we need to define the interface object as a
* property
* protoProto is the prototype to use for the interface prototype object.
* protoClass is the JSClass to use for the interface prototype object.
* This is null if we should not create an interface prototype
* object.
* constructorClass is the JSClass to use for the interface object.
* This is null if we should not create an interface object or
* if it should be a function object.
* constructor is the JSNative to use as a constructor. If this is non-null, it
* should be used as a JSNative to back the interface object, which
* should be a Function. If this is null, then we should create an
* object of constructorClass, unless that's also null, in which
* case we should not create an interface object at all.
* ctorNargs is the length of the constructor function; 0 if no constructor
* methods and properties are to be defined on the interface prototype object;
* these arguments are allowed to be null if there are no
* methods or properties respectively.
* constants are to be defined on the interface object and on the interface
* prototype object; allowed to be null if there are no constants.
* staticMethods are to be defined on the interface object; allowed to be null
* if there are no static methods.
*
* At least one of protoClass and constructorClass should be non-null.
* If constructorClass is non-null, the resulting interface object will be
* defined on the given global with property name |name|, which must also be
* non-null.
*
* returns the interface prototype object if protoClass is non-null, else it
* returns the interface object.
*/
JSObject*
CreateInterfaceObjects(JSContext* cx, JSObject* global, JSObject* receiver,
JSObject* protoProto, JSClass* protoClass,
JSClass* constructorClass, JSNative constructor,
unsigned ctorNargs, Prefable<JSFunctionSpec>* methods,
Prefable<JSPropertySpec>* properties,
Prefable<ConstantSpec>* constants,
Prefable<JSFunctionSpec>* staticMethods, const char* name);
template <class T>
inline bool
WrapNewBindingObject(JSContext* cx, JSObject* scope, T* value, JS::Value* vp)
{
JSObject* obj = value->GetWrapper();
if (obj && js::GetObjectCompartment(obj) == js::GetObjectCompartment(scope)) {
*vp = JS::ObjectValue(*obj);
return true;
}
if (!obj) {
bool triedToWrap;
obj = value->WrapObject(cx, scope, &triedToWrap);
if (!obj) {
// At this point, obj is null, so just return false. We could
// try to communicate triedToWrap to the caller, but in practice
// callers seem to be testing JS_IsExceptionPending(cx) to
// figure out whether WrapObject() threw instead.
return false;
}
}
// When called via XrayWrapper, we end up here while running in the
// chrome compartment. But the obj we have would be created in
// whatever the content compartment is. So at this point we need to
// make sure it's correctly wrapped for the compartment of |scope|.
// cx should already be in the compartment of |scope| here.
MOZ_ASSERT(js::IsObjectInContextCompartment(scope, cx));
*vp = JS::ObjectValue(*obj);
return JS_WrapValue(cx, vp);
}
// Helper for smart pointers (nsAutoPtr/nsRefPtr/nsCOMPtr).
template <template <typename> class SmartPtr, class T>
inline bool
WrapNewBindingObject(JSContext* cx, JSObject* scope, const SmartPtr<T>& value,
JS::Value* vp)
{
return WrapNewBindingObject(cx, scope, value.get(), vp);
}
template <class T>
inline bool
WrapNewBindingNonWrapperCachedObject(JSContext* cx, JSObject* scope, T* value,
JS::Value* vp)
{
// We try to wrap in the compartment of the underlying object of "scope"
JSObject* obj;
{
// scope for the JSAutoEnterCompartment so that we restore the
// compartment before we call JS_WrapValue.
JSAutoEnterCompartment ac;
if (js::IsWrapper(scope)) {
scope = xpc::Unwrap(cx, scope, false);
if (!scope || !ac.enter(cx, scope)) {
return false;
}
}
obj = value->WrapObject(cx, scope);
}
// We can end up here in all sorts of compartments, per above. Make
// sure to JS_WrapValue!
*vp = JS::ObjectValue(*obj);
return JS_WrapValue(cx, vp);
}
// Helper for smart pointers (nsAutoPtr/nsRefPtr/nsCOMPtr).
template <template <typename> class SmartPtr, typename T>
inline bool
WrapNewBindingNonWrapperCachedObject(JSContext* cx, JSObject* scope,
const SmartPtr<T>& value, JS::Value* vp)
{
return WrapNewBindingNonWrapperCachedObject(cx, scope, value.get(), vp);
}
/**
* A method to handle new-binding wrap failure, by possibly falling back to
* wrapping as a non-new-binding object.
*/
bool
DoHandleNewBindingWrappingFailure(JSContext* cx, JSObject* scope,
nsISupports* value, JS::Value* vp);
/**
* An easy way to call the above when you have a value which
* multiply-inherits from nsISupports.
*/
template <class T>
bool
HandleNewBindingWrappingFailure(JSContext* cx, JSObject* scope, T* value,
JS::Value* vp)
{
nsCOMPtr<nsISupports> val;
CallQueryInterface(value, getter_AddRefs(val));
return DoHandleNewBindingWrappingFailure(cx, scope, val, vp);
}
// Helper for smart pointers (nsAutoPtr/nsRefPtr/nsCOMPtr).
template <template <typename> class SmartPtr, class T>
MOZ_ALWAYS_INLINE bool
HandleNewBindingWrappingFailure(JSContext* cx, JSObject* scope,
const SmartPtr<T>& value, JS::Value* vp)
{
return HandleNewBindingWrappingFailure(cx, scope, value.get(), vp);
}
struct EnumEntry {
const char* value;
size_t length;
};
inline int
FindEnumStringIndex(JSContext* cx, JS::Value v, const EnumEntry* values, bool* ok)
{
// JS_StringEqualsAscii is slow as molasses, so don't use it here.
JSString* str = JS_ValueToString(cx, v);
if (!str) {
*ok = false;
return 0;
}
JS::Anchor<JSString*> anchor(str);
size_t length;
const jschar* chars = JS_GetStringCharsAndLength(cx, str, &length);
if (!chars) {
*ok = false;
return 0;
}
int i = 0;
for (const EnumEntry* value = values; value->value; ++value, ++i) {
if (length != value->length) {
continue;
}
bool equal = true;
const char* val = value->value;
for (size_t j = 0; j != length; ++j) {
if (unsigned(val[j]) != unsigned(chars[j])) {
equal = false;
break;
}
}
if (equal) {
*ok = true;
return i;
}
}
// XXX we don't know whether we're on the main thread, so play it safe
*ok = Throw<false>(cx, NS_ERROR_XPC_BAD_CONVERT_JS);
return 0;
}
inline nsWrapperCache*
GetWrapperCache(nsWrapperCache* cache)
{
return cache;
}
inline nsWrapperCache*
GetWrapperCache(nsGlobalWindow* not_allowed);
inline nsWrapperCache*
GetWrapperCache(void* p)
{
return NULL;
}
struct ParentObject {
template<class T>
ParentObject(T* aObject) :
mObject(aObject),
mWrapperCache(GetWrapperCache(aObject))
{}
template<class T, template<typename> class SmartPtr>
ParentObject(const SmartPtr<T>& aObject) :
mObject(aObject.get()),
mWrapperCache(GetWrapperCache(aObject.get()))
{}
ParentObject(nsISupports* aObject, nsWrapperCache* aCache) :
mObject(aObject),
mWrapperCache(aCache)
{}
nsISupports* const mObject;
nsWrapperCache* const mWrapperCache;
};
inline nsWrapperCache*
GetWrapperCache(const ParentObject& aParentObject)
{
return aParentObject.mWrapperCache;
}
template<class T>
inline nsISupports*
GetParentPointer(T* aObject)
{
return ToSupports(aObject);
}
inline nsISupports*
GetParentPointer(const ParentObject& aObject)
{
return ToSupports(aObject.mObject);
}
// Only set allowNativeWrapper to false if you really know you need it, if in
// doubt use true. Setting it to false disables security wrappers.
bool
XPCOMObjectToJsval(JSContext* cx, JSObject* scope, xpcObjectHelper &helper,
const nsIID* iid, bool allowNativeWrapper, JS::Value* rval);
template<class T>
inline bool
WrapObject(JSContext* cx, JSObject* scope, T* p, nsWrapperCache* cache,
const nsIID* iid, JS::Value* vp)
{
if (xpc_FastGetCachedWrapper(cache, scope, vp))
return true;
qsObjectHelper helper(p, cache);
return XPCOMObjectToJsval(cx, scope, helper, iid, true, vp);
}
template<class T>
inline bool
WrapObject(JSContext* cx, JSObject* scope, T* p, const nsIID* iid,
JS::Value* vp)
{
return WrapObject(cx, scope, p, GetWrapperCache(p), iid, vp);
}
template<class T>
inline bool
WrapObject(JSContext* cx, JSObject* scope, T* p, JS::Value* vp)
{
return WrapObject(cx, scope, p, NULL, vp);
}
template<class T>
inline bool
WrapObject(JSContext* cx, JSObject* scope, nsCOMPtr<T> &p, const nsIID* iid,
JS::Value* vp)
{
return WrapObject(cx, scope, p.get(), iid, vp);
}
template<class T>
inline bool
WrapObject(JSContext* cx, JSObject* scope, nsCOMPtr<T> &p, JS::Value* vp)
{
return WrapObject(cx, scope, p, NULL, vp);
}
template<class T>
inline bool
WrapObject(JSContext* cx, JSObject* scope, nsRefPtr<T> &p, const nsIID* iid,
JS::Value* vp)
{
return WrapObject(cx, scope, p.get(), iid, vp);
}
template<class T>
inline bool
WrapObject(JSContext* cx, JSObject* scope, nsRefPtr<T> &p, JS::Value* vp)
{
return WrapObject(cx, scope, p, NULL, vp);
}
template<>
inline bool
WrapObject<JSObject>(JSContext* cx, JSObject* scope, JSObject* p, JS::Value* vp)
{
vp->setObjectOrNull(p);
return true;
}
template<typename T>
static inline JSObject*
WrapNativeParent(JSContext* cx, JSObject* scope, const T& p)
{
if (!GetParentPointer(p))
return scope;
nsWrapperCache* cache = GetWrapperCache(p);
JSObject* obj;
if (cache && (obj = cache->GetWrapper())) {
#ifdef DEBUG
qsObjectHelper helper(GetParentPointer(p), cache);
JS::Value debugVal;
bool ok = XPCOMObjectToJsval(cx, scope, helper, NULL, false, &debugVal);
NS_ASSERTION(ok && JSVAL_TO_OBJECT(debugVal) == obj,
"Unexpected object in nsWrapperCache");
#endif
return obj;
}
qsObjectHelper helper(GetParentPointer(p), cache);
JS::Value v;
return XPCOMObjectToJsval(cx, scope, helper, NULL, false, &v) ?
JSVAL_TO_OBJECT(v) :
NULL;
}
static inline bool
InternJSString(JSContext* cx, jsid& id, const char* chars)
{
if (JSString *str = ::JS_InternString(cx, chars)) {
id = INTERNED_STRING_TO_JSID(cx, str);
return true;
}
return false;
}
// Spec needs a name property
template <typename Spec>
static bool
InitIds(JSContext* cx, Prefable<Spec>* prefableSpecs, jsid* ids)
{
MOZ_ASSERT(prefableSpecs);
MOZ_ASSERT(prefableSpecs->specs);
do {
// We ignore whether the set of ids is enabled and just intern all the IDs,
// because this is only done once per application runtime.
Spec* spec = prefableSpecs->specs;
do {
if (!InternJSString(cx, *ids, spec->name)) {
return false;
}
} while (++ids, (++spec)->name);
// We ran out of ids for that pref. Put a JSID_VOID in on the id
// corresponding to the list terminator for the pref.
*ids = JSID_VOID;
++ids;
} while ((++prefableSpecs)->specs);
return true;
}
JSBool
QueryInterface(JSContext* cx, unsigned argc, JS::Value* vp);
JSBool
ThrowingConstructor(JSContext* cx, unsigned argc, JS::Value* vp);
JSBool
ThrowingConstructorWorkers(JSContext* cx, unsigned argc, JS::Value* vp);
template<class T>
class NonNull
{
public:
NonNull()
#ifdef DEBUG
: inited(false)
#endif
{}
operator T&() {
MOZ_ASSERT(inited);
MOZ_ASSERT(ptr, "NonNull<T> was set to null");
return *ptr;
}
operator const T&() const {
MOZ_ASSERT(inited);
MOZ_ASSERT(ptr, "NonNull<T> was set to null");
return *ptr;
}
void operator=(T* t) {
ptr = t;
MOZ_ASSERT(ptr);
#ifdef DEBUG
inited = true;
#endif
}
T** Slot() {
#ifdef DEBUG
inited = true;
#endif
return &ptr;
}
protected:
T* ptr;
#ifdef DEBUG
bool inited;
#endif
};
template<class T>
class OwningNonNull
{
public:
OwningNonNull()
#ifdef DEBUG
: inited(false)
#endif
{}
operator T&() {
MOZ_ASSERT(inited);
MOZ_ASSERT(ptr, "OwningNonNull<T> was set to null");
return *ptr;
}
void operator=(T* t) {
init(t);
}
void operator=(const already_AddRefed<T>& t) {
init(t);
}
protected:
template<typename U>
void init(U t) {
ptr = t;
MOZ_ASSERT(ptr);
#ifdef DEBUG
inited = true;
#endif
}
nsRefPtr<T> ptr;
#ifdef DEBUG
bool inited;
#endif
};
enum StringificationBehavior {
eStringify,
eEmpty,
eNull
};
static inline bool
ConvertJSValueToString(JSContext* cx, const JS::Value& v, JS::Value* pval,
StringificationBehavior nullBehavior,
StringificationBehavior undefinedBehavior,
nsDependentString& result)
{
JSString *s;
if (v.isString()) {
s = v.toString();
} else {
StringificationBehavior behavior;
if (v.isNull()) {
behavior = nullBehavior;
} else if (v.isUndefined()) {
behavior = undefinedBehavior;
} else {
behavior = eStringify;
}
// If pval is null, that means the argument was optional and
// not passed; turn those into void strings if they're
// supposed to be stringified.
if (behavior != eStringify || !pval) {
// Here behavior == eStringify implies !pval, so both eNull and
// eStringify should end up with void strings.
result.SetIsVoid(behavior != eEmpty);
return true;
}
s = JS_ValueToString(cx, v);
if (!s) {
return false;
}
pval->setString(s); // Root the new string.
}
size_t len;
const jschar *chars = JS_GetStringCharsZAndLength(cx, s, &len);
if (!chars) {
return false;
}
result.Rebind(chars, len);
return true;
}
// Class for representing optional arguments.
template<typename T>
class Optional {
public:
Optional() {}
bool WasPassed() const {
return !mImpl.empty();
}
void Construct() {
mImpl.construct();
}
template <class T1, class T2>
void Construct(const T1 &t1, const T2 &t2) {
mImpl.construct(t1, t2);
}
const T& Value() const {
return mImpl.ref();
}
T& Value() {
return mImpl.ref();
}
private:
// Forbid copy-construction and assignment
Optional(const Optional& other) MOZ_DELETE;
const Optional &operator=(const Optional &other) MOZ_DELETE;
Maybe<T> mImpl;
};
// Specialization for strings.
template<>
class Optional<nsAString> {
public:
Optional() : mPassed(false) {}
bool WasPassed() const {
return mPassed;
}
void operator=(const nsAString* str) {
MOZ_ASSERT(str);
mStr = str;
mPassed = true;
}
const nsAString& Value() const {
MOZ_ASSERT(WasPassed());
return *mStr;
}
private:
// Forbid copy-construction and assignment
Optional(const Optional& other) MOZ_DELETE;
const Optional &operator=(const Optional &other) MOZ_DELETE;
bool mPassed;
const nsAString* mStr;
};
// Class for representing sequences in arguments. We use an auto array that can
// hold 16 elements, to avoid having to allocate in common cases. This needs to
// be fallible because web content controls the length of the array, and can
// easily try to create very large lengths.
template<typename T>
class Sequence : public AutoFallibleTArray<T, 16>
{
public:
Sequence() : AutoFallibleTArray<T, 16>() {}
};
} // namespace dom
} // namespace mozilla
#endif /* mozilla_dom_BindingUtils_h__ */