/* 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/. */
//! Utilities for the implementation of JSAPI proxy handlers.
#![deny(missing_docs)]
use dom::bindings::conversions::is_dom_proxy;
use dom::bindings::utils::delete_property_by_id;
use js::glue::{GetProxyHandler, GetProxyHandlerFamily, SetProxyExtra};
use js::glue::GetProxyExtra;
use js::glue::InvokeGetOwnPropertyDescriptor;
use js::jsapi::{DOMProxyShadowsResult, JSContext, JSObject, JSPROP_GETTER, PropertyDescriptor};
use js::jsapi::{Handle, HandleId, HandleObject, MutableHandle, ObjectOpResult};
use js::jsapi::{JSErrNum, JS_AlreadyHasOwnPropertyById, JS_StrictPropertyStub};
use js::jsapi::{JS_DefinePropertyById, JS_NewObjectWithGivenProto, SetDOMProxyInformation};
use js::jsapi::GetObjectProto;
use js::jsapi::GetStaticPrototype;
use js::jsapi::JS_GetPropertyDescriptorById;
use js::jsapi::MutableHandleObject;
use js::jsval::ObjectValue;
use libc;
use std::{mem, ptr};
static JSPROXYSLOT_EXPANDO: u32 = 0;
/// Determine if this id shadows any existing properties for this proxy.
pub unsafe extern "C" fn shadow_check_callback(cx: *mut JSContext,
object: HandleObject,
id: HandleId)
-> DOMProxyShadowsResult {
// TODO: support OverrideBuiltins when #12978 is fixed.
rooted!(in(cx) let expando = get_expando_object(object));
if !expando.get().is_null() {
let mut has_own = false;
if !JS_AlreadyHasOwnPropertyById(cx, expando.handle(), id, &mut has_own) {
return DOMProxyShadowsResult::ShadowCheckFailed;
}
if has_own {
return DOMProxyShadowsResult::ShadowsViaDirectExpando;
}
}
// Our expando, if any, didn't shadow, so we're not shadowing at all.
DOMProxyShadowsResult::DoesntShadow
}
/// Initialize the infrastructure for DOM proxy objects.
pub unsafe fn init() {
SetDOMProxyInformation(GetProxyHandlerFamily(),
JSPROXYSLOT_EXPANDO,
Some(shadow_check_callback));
}
/// Invoke the [[GetOwnProperty]] trap (`getOwnPropertyDescriptor`) on `proxy`,
/// with argument `id` and return the result, if it is not `undefined`.
/// Otherwise, walk along the prototype chain to find a property with that
/// name.
pub unsafe extern "C" fn get_property_descriptor(cx: *mut JSContext,
proxy: HandleObject,
id: HandleId,
desc: MutableHandle<PropertyDescriptor>)
-> bool {
let handler = GetProxyHandler(proxy.get());
if !InvokeGetOwnPropertyDescriptor(handler, cx, proxy, id, desc) {
return false;
}
if !desc.obj.is_null() {
return true;
}
rooted!(in(cx) let mut proto = ptr::null_mut());
if !GetObjectProto(cx, proxy, proto.handle_mut()) {
// FIXME(#11868) Should assign to desc.obj, desc.get() is a copy.
desc.get().obj = ptr::null_mut();
return true;
}
JS_GetPropertyDescriptorById(cx, proto.handle(), id, desc)
}
/// Defines an expando on the given `proxy`.
pub unsafe extern "C" fn define_property(cx: *mut JSContext,
proxy: HandleObject,
id: HandleId,
desc: Handle<PropertyDescriptor>,
result: *mut ObjectOpResult)
-> bool {
// FIXME: Workaround for https://github.com/rust-lang/rfcs/issues/718
let setter: *const libc::c_void = mem::transmute(desc.get().setter);
let setter_stub: unsafe extern fn(_, _, _, _, _) -> _ = JS_StrictPropertyStub;
let setter_stub: *const libc::c_void = mem::transmute(setter_stub);
if (desc.get().attrs & JSPROP_GETTER) != 0 && setter == setter_stub {
(*result).code_ = JSErrNum::JSMSG_GETTER_ONLY as ::libc::uintptr_t;
return true;
}
rooted!(in(cx) let expando = ensure_expando_object(cx, proxy));
JS_DefinePropertyById(cx, expando.handle(), id, desc, result)
}
/// Deletes an expando off the given `proxy`.
pub unsafe extern "C" fn delete(cx: *mut JSContext,
proxy: HandleObject,
id: HandleId,
bp: *mut ObjectOpResult)
-> bool {
rooted!(in(cx) let expando = get_expando_object(proxy));
if expando.is_null() {
(*bp).code_ = 0 /* OkCode */;
return true;
}
delete_property_by_id(cx, expando.handle(), id, bp)
}
/// Controls whether the Extensible bit can be changed
pub unsafe extern "C" fn prevent_extensions(_cx: *mut JSContext,
_proxy: HandleObject,
result: *mut ObjectOpResult)
-> bool {
(*result).code_ = JSErrNum::JSMSG_CANT_PREVENT_EXTENSIONS as ::libc::uintptr_t;
true
}
/// Reports whether the object is Extensible
pub unsafe extern "C" fn is_extensible(_cx: *mut JSContext,
_proxy: HandleObject,
succeeded: *mut bool)
-> bool {
*succeeded = true;
true
}
/// If `proxy` (underneath any functionally-transparent wrapper proxies) has as
/// its `[[GetPrototypeOf]]` trap the ordinary `[[GetPrototypeOf]]` behavior
/// defined for ordinary objects, set `*is_ordinary` to true and store `obj`'s
/// prototype in `proto`. Otherwise set `*isOrdinary` to false. In case of
/// error, both outparams have unspecified value.
///
/// This implementation always handles the case of the ordinary
/// `[[GetPrototypeOf]]` behavior. An alternative implementation will be
/// necessary for the Location object.
pub unsafe extern "C" fn get_prototype_if_ordinary(_: *mut JSContext,
proxy: HandleObject,
is_ordinary: *mut bool,
proto: MutableHandleObject)
-> bool {
*is_ordinary = true;
proto.set(GetStaticPrototype(proxy.get()));
true
}
/// Get the expando object, or null if there is none.
pub fn get_expando_object(obj: HandleObject) -> *mut JSObject {
unsafe {
assert!(is_dom_proxy(obj.get()));
let val = GetProxyExtra(obj.get(), JSPROXYSLOT_EXPANDO);
if val.is_undefined() {
ptr::null_mut()
} else {
val.to_object()
}
}
}
/// Get the expando object, or create it if it doesn't exist yet.
/// Fails on JSAPI failure.
pub fn ensure_expando_object(cx: *mut JSContext, obj: HandleObject) -> *mut JSObject {
unsafe {
assert!(is_dom_proxy(obj.get()));
let mut expando = get_expando_object(obj);
if expando.is_null() {
expando = JS_NewObjectWithGivenProto(cx, ptr::null_mut(), HandleObject::null());
assert!(!expando.is_null());
SetProxyExtra(obj.get(), JSPROXYSLOT_EXPANDO, &ObjectValue(expando));
}
expando
}
}
/// Set the property descriptor's object to `obj` and set it to enumerable,
/// and writable if `readonly` is true.
pub fn fill_property_descriptor(mut desc: MutableHandle<PropertyDescriptor>,
obj: *mut JSObject,
attrs: u32) {
desc.obj = obj;
desc.attrs = attrs;
desc.getter = None;
desc.setter = None;
}