C++ XPCWrappedNative类代码示例

nsIPrincipal*
nsXPConnect::GetPrincipal(JSObject* obj, bool allowShortCircuit) const
{
    MOZ_ASSERT(IS_WN_REFLECTOR(obj), "What kind of wrapper is this?");

    XPCWrappedNative* xpcWrapper = XPCWrappedNative::Get(obj);
    if (xpcWrapper) {
        if (allowShortCircuit) {
            nsIPrincipal* result = xpcWrapper->GetObjectPrincipal();
            if (result) {
                return result;
            }
        }

        // If not, check if it points to an nsIScriptObjectPrincipal
        nsCOMPtr<nsIScriptObjectPrincipal> objPrin =
            do_QueryInterface(xpcWrapper->Native());
        if (objPrin) {
            nsIPrincipal* result = objPrin->GetPrincipal();
            if (result) {
                return result;
            }
        }
    }

    return nullptr;
}

nsISupports*
castNativeFromWrapper(JSContext *cx,
                      JSObject *obj,
                      uint32_t interfaceBit,
                      uint32_t protoID,
                      int32_t protoDepth,
                      nsISupports **pRef,
                      jsval *pVal,
                      nsresult *rv)
{
    XPCWrappedNative *wrapper;
    XPCWrappedNativeTearOff *tearoff;
    JSObject *cur;

    if (IS_WRAPPER_CLASS(js::GetObjectClass(obj))) {
        cur = obj;
        wrapper = IS_WN_WRAPPER_OBJECT(cur) ?
                  (XPCWrappedNative*)xpc_GetJSPrivate(obj) :
                  nullptr;
        tearoff = nullptr;
    } else {
        *rv = getWrapper(cx, obj, &wrapper, &cur, &tearoff);
        if (NS_FAILED(*rv))
            return nullptr;
    }

    nsISupports *native;
    if (wrapper) {
        native = wrapper->GetIdentityObject();
        cur = wrapper->GetFlatJSObject();
        if (!native || !HasBitInInterfacesBitmap(cur, interfaceBit)) {
            native = nullptr;
        }
    } else if (cur && IS_SLIM_WRAPPER(cur)) {
        native = static_cast<nsISupports*>(xpc_GetJSPrivate(cur));
        if (!native || !HasBitInInterfacesBitmap(cur, interfaceBit)) {
            native = nullptr;
        }
    } else if (cur && protoDepth >= 0) {
        const mozilla::dom::DOMClass* domClass =
            mozilla::dom::GetDOMClass(cur);
        native = mozilla::dom::UnwrapDOMObject<nsISupports>(cur);
        if (native &&
            (uint32_t)domClass->mInterfaceChain[protoDepth] != protoID) {
            native = nullptr;
        }
    } else {
        native = nullptr;
    }

    if (native) {
        *pRef = nullptr;
        *pVal = OBJECT_TO_JSVAL(cur);
        *rv = NS_OK;
    } else {
        *rv = NS_ERROR_XPC_BAD_CONVERT_JS;
    }

    return native;
}

JSBool
XPC_COW_RewrapForChrome(JSContext *cx, JSObject *wrapperObj, jsval *vp)
{
  jsval v = *vp;
  if (JSVAL_IS_PRIMITIVE(v)) {
    return JS_TRUE;
  }

  // We're rewrapping for chrome, so this is safe.
  JSObject *obj = GetWrappedJSObject(cx, JSVAL_TO_OBJECT(v));
  if (!obj) {
    *vp = JSVAL_NULL;
    return JS_TRUE;
  }

  XPCWrappedNative *wn;
  if (IS_WRAPPER_CLASS(STOBJ_GET_CLASS(obj)) &&
      (wn = XPCWrappedNative::GetWrappedNativeOfJSObject(cx, obj)) &&
      !nsXPCWrappedJSClass::IsWrappedJS(wn->Native())) {
    // Return an explicit XPCNativeWrapper in case "chrome" code happens to be
    // XBL code cloned into an untrusted context.
    return XPCNativeWrapperCtor(cx, obj, 1, vp, vp);
  }

  return XPC_SJOW_Construct(cx, obj, 1, vp, vp);
}

static JSBool
XPC_COW_Equality(JSContext *cx, JSObject *obj, jsval v, JSBool *bp)
{
  // Convert both sides to XPCWrappedNative and see if they match.
  if (JSVAL_IS_PRIMITIVE(v)) {
    *bp = JS_FALSE;
    return JS_TRUE;
  }

  JSObject *test = GetWrappedJSObject(cx, JSVAL_TO_OBJECT(v));

  obj = GetWrappedObject(cx, obj);
  if (!obj) {
    return ThrowException(NS_ERROR_ILLEGAL_VALUE, cx);
  }
  XPCWrappedNative *other =
    XPCWrappedNative::GetWrappedNativeOfJSObject(cx, test);
  if (!other) {
    *bp = JS_FALSE;
    return JS_TRUE;
  }

  XPCWrappedNative *me = XPCWrappedNative::GetWrappedNativeOfJSObject(cx, obj);
  obj = me->GetFlatJSObject();
  test = other->GetFlatJSObject();
  return ((JSExtendedClass *)STOBJ_GET_CLASS(obj))->
    equality(cx, obj, OBJECT_TO_JSVAL(test), bp);
}

JSObject *
WrapperFactory::WrapForSameCompartment(JSContext *cx, HandleObject objArg)
{
    RootedObject obj(cx, objArg);
    MOZ_ASSERT(js::IsObjectInContextCompartment(obj, cx));

    // NB: The contract of WrapForSameCompartment says that |obj| may or may not
    // be a security wrapper. These checks implicitly handle the security
    // wrapper case.

    // Outerize if necessary. This, in combination with the check in
    // PrepareForUnwrapping, means that calling JS_Wrap* always outerizes.
    obj = JS_ObjectToOuterObject(cx, obj);
    NS_ENSURE_TRUE(obj, nullptr);

    if (dom::GetSameCompartmentWrapperForDOMBinding(*obj.address())) {
        return obj;
    }

    MOZ_ASSERT(!dom::IsDOMObject(obj));

    if (!IS_WN_WRAPPER(obj))
        return obj;

    // Extract the WN. It should exist.
    XPCWrappedNative *wn = static_cast<XPCWrappedNative *>(xpc_GetJSPrivate(obj));
    MOZ_ASSERT(wn, "Trying to wrap a dead WN!");

    // The WN knows what to do.
    RootedObject wrapper(cx, wn->GetSameCompartmentSecurityWrapper(cx));
    MOZ_ASSERT_IF(wrapper != obj && IsComponentsObject(js::UncheckedUnwrap(obj)),
                  !Wrapper::wrapperHandler(wrapper)->isSafeToUnwrap());
    return wrapper;
}

static JSObject *
EnsureExpandoObject(JSContext *cx, JSObject *holder)
{
    NS_ASSERTION(holder->getJSClass() == &HolderClass, "expected a native property holder object");
    JSObject *expando = GetExpandoObject(holder);
    if (expando)
        return expando;
    CompartmentPrivate *priv =
        (CompartmentPrivate *)JS_GetCompartmentPrivate(cx, holder->compartment());
    XPCWrappedNative *wn = GetWrappedNativeFromHolder(holder);
    expando = priv->LookupExpandoObject(wn);
    if (!expando) {
        expando = JS_NewObjectWithGivenProto(cx, nsnull, nsnull, holder->getParent());
        if (!expando)
            return NULL;
        // Add the expando object to the expando map to keep it alive.
        if (!priv->RegisterExpandoObject(wn, expando)) {
            JS_ReportOutOfMemory(cx);
            return NULL;
        }
        // Make sure the wn stays alive so it keeps the expando object alive.
        nsRefPtr<nsXPCClassInfo> ci;
        CallQueryInterface(wn->Native(), getter_AddRefs(ci));
        if (ci)
            ci->PreserveWrapper(wn->Native());
    }
    holder->setSlot(JSSLOT_EXPANDO, ObjectValue(*expando));
    return expando;
}

static JSBool
holder_set(JSContext *cx, JSObject *wrapper, jsid id, JSBool strict, jsval *vp)
{
    wrapper = FindWrapper(wrapper);

    JSObject *holder = GetHolder(wrapper);
    if (IsResolving(holder, id)) {
        return true;
    }

    XPCWrappedNative *wn = GetWrappedNativeFromHolder(holder);
    if (NATIVE_HAS_FLAG(wn, WantSetProperty)) {
        JSAutoEnterCompartment ac;
        if (!ac.enter(cx, holder))
            return false;
        PRBool retval = true;
        nsresult rv = wn->GetScriptableCallback()->SetProperty(wn, cx, wrapper, id, vp, &retval);
        if (NS_FAILED(rv) || !retval) {
            if (retval)
                XPCThrower::Throw(rv, cx);
            return false;
        }
    }
    return true;
}

static JSBool
XrayToString(JSContext *cx, uintN argc, jsval *vp)
{
    JSObject *wrapper = JS_THIS_OBJECT(cx, vp);
    if (!wrapper->isWrapper() || !WrapperFactory::IsXrayWrapper(wrapper)) {
        JS_ReportError(cx, "XrayToString called on an incompatible object");
        return false;
    }
    JSObject *holder = GetHolder(wrapper);
    XPCWrappedNative *wn = GetWrappedNativeFromHolder(holder);
    JSObject *wrappednative = wn->GetFlatJSObject();

    XPCCallContext ccx(JS_CALLER, cx, wrappednative);
    char *wrapperStr = wn->ToString(ccx);
    if (!wrapperStr) {
        JS_ReportOutOfMemory(cx);
        return false;
    }

    nsAutoString result(NS_LITERAL_STRING("[object XrayWrapper "));
    result.AppendASCII(wrapperStr);
    JS_smprintf_free(wrapperStr);
    result.Append(']');

    JSString *str = JS_NewUCStringCopyN(cx, reinterpret_cast<const jschar *>(result.get()),
                                        result.Length());
    if (!str)
        return false;

    *vp = STRING_TO_JSVAL(str);
    return true;
}

/**
 * Get the interface name and member name (for error messages).
 *
 * We could instead have each quick stub pass its name to the error-handling
 * functions, as that name is statically known.  But that would be redundant;
 * the information is handy at runtime anyway.  Also, this code often produces
 * a more specific error message, e.g. "[nsIDOMHTMLDocument.appendChild]"
 * rather than "[nsIDOMNode.appendChild]".
 */
static void
GetMemberInfo(JSObject *obj, jsid memberId, const char **ifaceName)
{
    *ifaceName = "Unknown";

    // Don't try to generate a useful name if there are security wrappers,
    // because it isn't worth the risk of something going wrong just to generate
    // an error message. Instead, only handle the simple case where we have the
    // reflector in hand.
    if (IS_WRAPPER_CLASS(js::GetObjectClass(obj))) {
        XPCWrappedNativeProto *proto;
        if (IS_SLIM_WRAPPER_OBJECT(obj)) {
            proto = GetSlimWrapperProto(obj);
        } else {
            MOZ_ASSERT(IS_WN_WRAPPER_OBJECT(obj));
            XPCWrappedNative *wrapper =
                static_cast<XPCWrappedNative *>(js::GetObjectPrivate(obj));
            proto = wrapper->GetProto();
        }
        if (proto) {
            XPCNativeSet *set = proto->GetSet();
            if (set) {
                XPCNativeMember *member;
                XPCNativeInterface *iface;

                if (set->FindMember(memberId, &member, &iface))
                    *ifaceName = iface->GetNameString();
            }
        }
    }
}

XPCWrappedNative*
XPCCallContext::UnwrapThisIfAllowed(HandleObject obj, HandleObject fun, unsigned argc)
{
    // We should only get here for objects that aren't safe to unwrap.
    MOZ_ASSERT(!js::CheckedUnwrap(obj));
    MOZ_ASSERT(js::IsObjectInContextCompartment(obj, mJSContext));

    // We can't do anything here without a function.
    if (!fun)
        return nullptr;

    // Determine if we're allowed to unwrap the security wrapper to invoke the
    // method.
    //
    // We have the Interface and Member that this corresponds to, but
    // unfortunately our access checks are based on the object class name and
    // property name. So we cheat a little bit here - we verify that the object
    // does indeed implement the method's Interface, and then just check that we
    // can successfully access property with method's name from the object.

    // First, get the XPCWN out of the underlying object. We should have a wrapper
    // here, potentially an outer window proxy, and then an XPCWN.
    MOZ_ASSERT(js::IsWrapper(obj));
    RootedObject unwrapped(mJSContext, js::UncheckedUnwrap(obj, /* stopAtOuter = */ false));
#ifdef DEBUG
    JS::Rooted<JSObject*> wrappedObj(mJSContext, js::Wrapper::wrappedObject(obj));
    MOZ_ASSERT(unwrapped == JS_ObjectToInnerObject(mJSContext, wrappedObj));
#endif

    // Make sure we have an XPCWN, and grab it.
    if (!IS_WN_REFLECTOR(unwrapped))
        return nullptr;
    XPCWrappedNative *wn = XPCWrappedNative::Get(unwrapped);

    // Next, get the call info off the function object.
    XPCNativeInterface *interface;
    XPCNativeMember *member;
    XPCNativeMember::GetCallInfo(fun, &interface, &member);

    // To be extra safe, make sure that the underlying native implements the
    // interface before unwrapping. Even if we didn't check this, we'd still
    // theoretically fail during tearoff lookup for mismatched methods.
    if (!wn->HasInterfaceNoQI(*interface->GetIID()))
        return nullptr;

    // See if the access is permitted.
    //
    // NB: This calculation of SET vs GET is a bit wonky, but that's what
    // XPC_WN_GetterSetter does.
    bool set = argc && argc != NO_ARGS && member->IsWritableAttribute();
    js::Wrapper::Action act = set ? js::Wrapper::SET : js::Wrapper::GET;
    const js::Wrapper *handler = js::Wrapper::wrapperHandler(obj);
    bool ignored;
    JS::Rooted<jsid> id(mJSContext, member->GetName());
    if (!handler->enter(mJSContext, obj, id, act, &ignored))
        return nullptr;

    // Ok, this call is safe.
    return wn;
}

WNSecPolicyClearer(JSDHashTable *table, JSDHashEntryHdr *hdr,
                    uint32 number, void *arg)
{
    XPCWrappedNative* wrapper = ((Native2WrappedNativeMap::Entry*)hdr)->value;
    if(wrapper->HasProto() && !wrapper->HasSharedProto())
        *(wrapper->GetProto()->GetSecurityInfoAddr()) = nsnull;
    return JS_DHASH_NEXT;
}

DEBUG_WrapperChecker(JSDHashTable *table, JSDHashEntryHdr *hdr,
                     uint32 number, void *arg)
{
    XPCWrappedNative* wrapper = (XPCWrappedNative*)((JSDHashEntryStub*)hdr)->key;
    NS_ASSERTION(!wrapper->IsValid(), "found a 'valid' wrapper!");
    ++ *((int*)arg);
    return JS_DHASH_NEXT;
}

static void
WrappedNativeObjectMoved(JSObject* obj, const JSObject* old)
{
    nsISupports* p = static_cast<nsISupports*>(xpc_GetJSPrivate(obj));
    if (!p)
        return;

    XPCWrappedNative* wrapper = static_cast<XPCWrappedNative*>(p);
    wrapper->FlatJSObjectMoved(obj, old);
}

static JSDHashOperator
WrappedNativeJSGCThingTracer(JSDHashTable *table, JSDHashEntryHdr *hdr,
                             uint32_t number, void *arg)
{
    XPCWrappedNative* wrapper = ((Native2WrappedNativeMap::Entry*)hdr)->value;
    if (wrapper->HasExternalReference() && !wrapper->IsWrapperExpired())
        wrapper->TraceSelf((JSTracer *)arg);

    return JS_DHASH_NEXT;
}

JSBool
xpc_JSObjectIsID(JSContext *cx, JSObject* obj)
{
    NS_ASSERTION(cx && obj, "bad param");
    // NOTE: this call does NOT addref
    XPCWrappedNative* wrapper =
        XPCWrappedNative::GetWrappedNativeOfJSObject(cx, obj);
    return wrapper &&
           (wrapper->HasInterfaceNoQI(NS_GET_IID(nsIJSID))  ||
            wrapper->HasInterfaceNoQI(NS_GET_IID(nsIJSIID)) ||
            wrapper->HasInterfaceNoQI(NS_GET_IID(nsIJSCID)));
}