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/* 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::jsapi::{JSContext, JSPropertyDescriptor, JSObject, JSString};
use js::jsapi::{JS_GetPropertyDescriptorById, JS_NewStringCopyN};
use js::jsapi::{JS_DefinePropertyById6, JS_NewObjectWithGivenProto};
use js::jsapi::{JS_StrictPropertyStub, JSErrNum};
use js::jsapi::{Handle, HandleObject, HandleId, MutableHandle, RootedObject, ObjectOpResult};
use js::jsapi::AutoIdVector;
use js::jsapi::GetObjectProto;
use js::jsval::ObjectValue;
use js::glue::GetProxyExtra;
use js::glue::{SetProxyExtra, GetProxyHandler};
use js::glue::InvokeGetOwnPropertyDescriptor;
use js::{JSPROP_GETTER, JSPROP_ENUMERATE, JSPROP_READONLY};
use js::{JSTrue, JSFalse};
use libc;
use std::mem;
use std::ptr;
static JSPROXYSLOT_EXPANDO: u32 = 0;
/// 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 fn get_property_descriptor(cx: *mut JSContext,
proxy: HandleObject,
id: HandleId,
desc: MutableHandle<JSPropertyDescriptor>)
-> u8 {
let handler = GetProxyHandler(proxy.get());
if InvokeGetOwnPropertyDescriptor(handler, cx, proxy, id, desc) == 0 {
return JSFalse;
}
if !desc.get().obj.is_null() {
return JSTrue;
}
let mut proto = RootedObject::new(cx, ptr::null_mut());
if GetObjectProto(cx, proxy, proto.handle_mut()) == 0 {
desc.get().obj = ptr::null_mut();
return JSTrue;
}
JS_GetPropertyDescriptorById(cx, proto.handle(), id, desc)
}
/// Defines an expando on the given `proxy`.
pub unsafe extern fn define_property(cx: *mut JSContext, proxy: HandleObject,
id: HandleId, desc: Handle<JSPropertyDescriptor>,
result: *mut ObjectOpResult)
-> u8 {
//FIXME: Workaround for https://github.com/mozilla/rust/issues/13385
let setter: *const libc::c_void = mem::transmute(desc.get().setter);
let setter_stub: *const libc::c_void = mem::transmute(JS_StrictPropertyStub);
if (desc.get().attrs & JSPROP_GETTER) != 0 && setter == setter_stub {
(*result).code_ = JSErrNum::JSMSG_GETTER_ONLY as u32;
return JSTrue;
}
let expando = RootedObject::new(cx, ensure_expando_object(cx, proxy));
JS_DefinePropertyById6(cx, expando.handle(), id, desc, result)
}
/// Deletes an expando off the given `proxy`.
pub unsafe extern fn delete(cx: *mut JSContext, proxy: HandleObject, id: HandleId,
bp: *mut ObjectOpResult) -> u8 {
let expando = RootedObject::new(cx, get_expando_object(proxy));
if expando.ptr.is_null() {
(*bp).code_ = 0 /* OkCode */;
return JSTrue;
}
delete_property_by_id(cx, expando.handle(), id, bp)
}
/// Stub for ownPropertyKeys
pub unsafe extern fn own_property_keys(cx: *mut JSContext,
proxy: HandleObject,
props: *mut AutoIdVector) -> u8 {
// FIXME: implement this
// https://github.com/servo/servo/issues/6390
JSTrue
}
/// Controls whether the Extensible bit can be changed
pub unsafe extern fn prevent_extensions(_cx: *mut JSContext,
_proxy: HandleObject,
result: *mut ObjectOpResult) -> u8 {
(*result).code_ = JSErrNum::JSMSG_CANT_PREVENT_EXTENSIONS as u32;
return JSTrue;
}
/// Reports whether the object is Extensible
pub unsafe extern fn is_extensible(_cx: *mut JSContext, _proxy: HandleObject,
succeeded: *mut u8) -> u8 {
*succeeded = JSTrue;
return JSTrue;
}
/// Returns the stringification of an object with class `name`.
pub fn object_to_string(cx: *mut JSContext, name: &str) -> *mut JSString {
unsafe {
let result = format!("[object {}]", name);
let chars = result.as_ptr() as *const libc::c_char;
let length = result.len() as libc::size_t;
let string = JS_NewStringCopyN(cx, chars, length);
assert!(!string.is_null());
return string;
}
}
/// 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));
}
return 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(desc: &mut JSPropertyDescriptor,
obj: *mut JSObject, readonly: bool) {
desc.obj = obj;
desc.attrs = if readonly { JSPROP_READONLY } else { 0 } | JSPROP_ENUMERATE;
desc.getter = None;
desc.setter = None;
}
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