servo/components/script/window_named_properties.rs

/* 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/. */

use crate::dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
use crate::dom::bindings::proxyhandler::fill_property_descriptor;
use crate::dom::bindings::root::Root;
use crate::dom::bindings::utils::has_property_on_prototype;
use crate::dom::globalscope::GlobalScope;
use crate::dom::window::Window;
use crate::js::conversions::ToJSValConvertible;
use crate::script_runtime::JSContext as SafeJSContext;
use js::conversions::jsstr_to_string;
use js::error::throw_type_error;
use js::glue::RUST_JSID_TO_STRING;
use js::glue::{CreateProxyHandler, NewProxyObject, ProxyTraps, RUST_JSID_IS_STRING};
use js::jsapi::JS_SetImmutablePrototype;
use js::jsapi::{Handle, HandleObject, JSClass, JSContext, JSErrNum, UndefinedHandleValue};
use js::jsapi::{
    HandleId, JSClass_NON_NATIVE, MutableHandle, ObjectOpResult, PropertyDescriptor,
    ProxyClassExtension, ProxyClassOps, ProxyObjectOps, JSCLASS_DELAY_METADATA_BUILDER,
    JSCLASS_IS_PROXY, JSCLASS_RESERVED_SLOTS_MASK, JSCLASS_RESERVED_SLOTS_SHIFT,
};
use js::jsval::UndefinedValue;
use js::rust::IntoHandle;
use js::rust::{Handle as RustHandle, MutableHandle as RustMutableHandle};
use js::rust::{HandleObject as RustHandleObject, MutableHandleObject as RustMutableHandleObject};
use libc;
use std::ptr;

struct SyncWrapper(*const libc::c_void);
#[allow(unsafe_code)]
unsafe impl Sync for SyncWrapper {}

lazy_static! {
    static ref HANDLER: SyncWrapper = {
        let traps = ProxyTraps {
            enter: None,
            getOwnPropertyDescriptor: Some(get_own_property_descriptor),
            defineProperty: Some(define_property),
            ownPropertyKeys: None,
            delete_: Some(delete),
            enumerate: None,
            getPrototypeIfOrdinary: None,
            preventExtensions: Some(prevent_extensions),
            isExtensible: Some(is_extensible),
            has: None,
            get: None,
            set: None,
            call: None,
            construct: None,
            hasOwn: None,
            getOwnEnumerablePropertyKeys: None,
            nativeCall: None,
            hasInstance: None,
            objectClassIs: None,
            className: Some(class_name),
            fun_toString: None,
            boxedValue_unbox: None,
            defaultValue: None,
            trace: None,
            finalize: None,
            objectMoved: None,
            isCallable: None,
            isConstructor: None,
        };

        #[allow(unsafe_code)]
        unsafe {
            SyncWrapper(CreateProxyHandler(&traps, ptr::null()))
        }
    };
}

#[allow(unsafe_code)]
unsafe extern "C" fn get_own_property_descriptor(
    cx: *mut JSContext,
    proxy: HandleObject,
    id: HandleId,
    desc: MutableHandle<PropertyDescriptor>,
) -> bool {
    let cx = SafeJSContext::from_ptr(cx);
    if !RUST_JSID_IS_STRING(id) {
        // Nothing to do if we're resolving a non-string property.
        return true;
    }

    let mut found = false;
    if !has_property_on_prototype(
        *cx,
        RustHandle::from_raw(proxy),
        RustHandle::from_raw(id),
        &mut found,
    ) {
        return false;
    }
    if found {
        return true;
    }

    let s = jsstr_to_string(*cx, RUST_JSID_TO_STRING(id));
    if s.is_empty() {
        return true;
    }

    let window = Root::downcast::<Window>(GlobalScope::from_object(proxy.get()))
        .expect("global is not a window");
    if let Some(obj) = window.NamedGetter(cx, s.into()) {
        rooted!(in(*cx) let mut val = UndefinedValue());
        obj.to_jsval(*cx, val.handle_mut());
        fill_property_descriptor(RustMutableHandle::from_raw(desc), proxy.get(), val.get(), 0);
    }
    return true;
}

#[allow(unsafe_code)]
unsafe extern "C" fn define_property(
    cx: *mut JSContext,
    _proxy: HandleObject,
    _id: HandleId,
    _desc: Handle<PropertyDescriptor>,
    _result: *mut ObjectOpResult,
) -> bool {
    throw_type_error(
        cx,
        "Not allowed to define a property on the named properties object.",
    );
    false
}

#[allow(unsafe_code)]
unsafe extern "C" fn delete(
    _cx: *mut JSContext,
    _proxy: HandleObject,
    _id: HandleId,
    result: *mut ObjectOpResult,
) -> bool {
    (*result).code_ = JSErrNum::JSMSG_CANT_DELETE_WINDOW_NAMED_PROPERTY as usize;
    true
}

#[allow(unsafe_code)]
unsafe extern "C" fn prevent_extensions(
    _cx: *mut JSContext,
    _proxy: HandleObject,
    result: *mut ObjectOpResult,
) -> bool {
    (*result).code_ = JSErrNum::JSMSG_CANT_PREVENT_EXTENSIONS as usize;
    true
}

#[allow(unsafe_code)]
unsafe extern "C" fn is_extensible(
    _cx: *mut JSContext,
    _proxy: HandleObject,
    extensible: *mut bool,
) -> bool {
    *extensible = true;
    true
}

#[allow(unsafe_code)]
unsafe extern "C" fn class_name(_cx: *mut JSContext, _proxy: HandleObject) -> *const i8 {
    &b"WindowProperties" as *const _ as *const i8
}

// Maybe this should be a DOMJSClass. See https://bugzilla.mozilla.org/show_bug.cgi?id=787070
static CLASS: JSClass = JSClass {
    name: b"WindowProperties\0" as *const u8 as *const libc::c_char,
    flags: JSClass_NON_NATIVE |
        JSCLASS_IS_PROXY |
        JSCLASS_DELAY_METADATA_BUILDER |
        ((1 & JSCLASS_RESERVED_SLOTS_MASK) << JSCLASS_RESERVED_SLOTS_SHIFT), /* JSCLASS_HAS_RESERVED_SLOTS(1) */
    cOps: &ProxyClassOps,
    spec: ptr::null(),
    ext: &ProxyClassExtension,
    oOps: &ProxyObjectOps,
};

#[allow(unsafe_code)]
pub fn create(
    cx: SafeJSContext,
    proto: RustHandleObject,
    mut properties_obj: RustMutableHandleObject,
) {
    unsafe {
        properties_obj.set(NewProxyObject(
            *cx,
            HANDLER.0,
            UndefinedHandleValue,
            proto.get(),
            // TODO: pass proper clasp
            &CLASS,
            true,
        ));
        assert!(!properties_obj.get().is_null());
        let mut succeeded = false;
        assert!(JS_SetImmutablePrototype(
            *cx,
            properties_obj.handle().into_handle(),
            &mut succeeded
        ));
        assert!(succeeded);
    }
}