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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/. */
//! This module implements structured cloning, as defined by [HTML]
//! (https://html.spec.whatwg.org/multipage/#safe-passing-of-structured-data).
use dom::bindings::error::{Error, Fallible};
use dom::globalscope::GlobalScope;
use js::jsapi::{HandleValue, MutableHandleValue};
use js::jsapi::{JSContext, JS_ReadStructuredClone, JS_STRUCTURED_CLONE_VERSION};
use js::jsapi::{JS_ClearPendingException, JS_WriteStructuredClone};
use libc::size_t;
use std::ptr;
use std::slice;
/// A buffer for a structured clone.
pub enum StructuredCloneData {
/// A non-serializable (default) variant
Struct(*mut u64, size_t),
/// A variant that can be serialized
Vector(Vec<u8>)
}
impl StructuredCloneData {
/// Writes a structured clone. Returns a `DataClone` error if that fails.
pub fn write(cx: *mut JSContext, message: HandleValue) -> Fallible<StructuredCloneData> {
let mut data = ptr::null_mut();
let mut nbytes = 0;
let result = unsafe {
JS_WriteStructuredClone(cx,
message,
&mut data,
&mut nbytes,
ptr::null(),
ptr::null_mut(),
HandleValue::undefined())
};
if !result {
unsafe {
JS_ClearPendingException(cx);
}
return Err(Error::DataClone);
}
Ok(StructuredCloneData::Struct(data, nbytes))
}
/// Converts a StructuredCloneData to Vec<u8> for inter-thread sharing
pub fn move_to_arraybuffer(self) -> Vec<u8> {
match self {
StructuredCloneData::Struct(data, nbytes) => {
unsafe {
slice::from_raw_parts(data as *mut u8, nbytes).to_vec()
}
}
StructuredCloneData::Vector(msg) => msg
}
}
/// Reads a structured clone.
///
/// Panics if `JS_ReadStructuredClone` fails.
fn read_clone(global: &GlobalScope, data: *mut u64, nbytes: size_t, rval: MutableHandleValue) {
unsafe {
assert!(JS_ReadStructuredClone(global.get_cx(),
data,
nbytes,
JS_STRUCTURED_CLONE_VERSION,
rval,
ptr::null(),
ptr::null_mut()));
}
}
/// Thunk for the actual `read_clone` method. Resolves proper variant for read_clone.
pub fn read(self, global: &GlobalScope, rval: MutableHandleValue) {
match self {
StructuredCloneData::Vector(mut vec_msg) => {
let nbytes = vec_msg.len();
let data = vec_msg.as_mut_ptr() as *mut u64;
StructuredCloneData::read_clone(global, data, nbytes, rval);
}
StructuredCloneData::Struct(data, nbytes) => StructuredCloneData::read_clone(global, data, nbytes, rval)
}
}
}
unsafe impl Send for StructuredCloneData {}
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