/
cpp.rs
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/
cpp.rs
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// Protocol Buffers - Google's data interchange format
// Copyright 2023 Google LLC. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google LLC. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// Rust Protobuf runtime using the C++ kernel.
use crate::__internal::{Private, RawArena, RawMessage};
use std::alloc::Layout;
use std::cell::UnsafeCell;
use std::fmt;
use std::marker::PhantomData;
use std::mem::MaybeUninit;
use std::ops::Deref;
use std::ptr::{self, NonNull};
/// A wrapper over a `proto2::Arena`.
///
/// This is not a safe wrapper per se, because the allocation functions still
/// have sharp edges (see their safety docs for more info).
///
/// This is an owning type and will automatically free the arena when
/// dropped.
///
/// Note that this type is neither `Sync` nor `Send`.
#[derive(Debug)]
pub struct Arena {
#[allow(dead_code)]
ptr: RawArena,
_not_sync: PhantomData<UnsafeCell<()>>,
}
impl Arena {
/// Allocates a fresh arena.
#[inline]
pub fn new() -> Self {
Self { ptr: NonNull::dangling(), _not_sync: PhantomData }
}
/// Returns the raw, C++-managed pointer to the arena.
#[inline]
pub fn raw(&self) -> ! {
unimplemented!()
}
/// Allocates some memory on the arena.
///
/// # Safety
///
/// TODO alignment requirement for layout
#[inline]
pub unsafe fn alloc(&self, _layout: Layout) -> &mut [MaybeUninit<u8>] {
unimplemented!()
}
/// Resizes some memory on the arena.
///
/// # Safety
///
/// After calling this function, `ptr` is essentially zapped. `old` must
/// be the layout `ptr` was allocated with via [`Arena::alloc()`].
/// TODO alignment for layout
#[inline]
pub unsafe fn resize(&self, _ptr: *mut u8, _old: Layout, _new: Layout) -> &[MaybeUninit<u8>] {
unimplemented!()
}
}
impl Drop for Arena {
#[inline]
fn drop(&mut self) {
// unimplemented
}
}
/// Serialized Protobuf wire format data. It's typically produced by
/// `<Message>.serialize()`.
///
/// This struct is ABI-compatible with the equivalent struct on the C++ side. It
/// owns (and drops) its data.
#[repr(C)]
pub struct SerializedData {
/// Owns the memory.
data: NonNull<u8>,
len: usize,
}
impl SerializedData {
/// Constructs owned serialized data from raw components.
///
/// # Safety
/// - `data` must be readable for `len` bytes.
/// - `data` must be an owned pointer and valid until deallocated.
/// - `data` must have been allocated by the Rust global allocator with a
/// size of `len` and align of 1.
pub unsafe fn from_raw_parts(data: NonNull<u8>, len: usize) -> Self {
Self { data, len }
}
/// Gets a raw slice pointer.
pub fn as_ptr(&self) -> *const [u8] {
ptr::slice_from_raw_parts(self.data.as_ptr(), self.len)
}
/// Gets a mutable raw slice pointer.
fn as_mut_ptr(&mut self) -> *mut [u8] {
ptr::slice_from_raw_parts_mut(self.data.as_ptr(), self.len)
}
}
impl Deref for SerializedData {
type Target = [u8];
fn deref(&self) -> &Self::Target {
// SAFETY: `data` is valid for `len` bytes until deallocated as promised by
// `from_raw_parts`.
unsafe { &*self.as_ptr() }
}
}
impl Drop for SerializedData {
fn drop(&mut self) {
// SAFETY: `data` was allocated by the Rust global allocator with a
// size of `len` and align of 1 as promised by `from_raw_parts`.
unsafe { drop(Box::from_raw(self.as_mut_ptr())) }
}
}
impl fmt::Debug for SerializedData {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Debug::fmt(self.deref(), f)
}
}
pub type BytesPresentMutData<'msg> = crate::vtable::RawVTableOptionalMutatorData<'msg, [u8]>;
pub type BytesAbsentMutData<'msg> = crate::vtable::RawVTableOptionalMutatorData<'msg, [u8]>;
pub type InnerBytesMut<'msg> = crate::vtable::RawVTableMutator<'msg, [u8]>;
/// The raw contents of every generated message.
#[derive(Debug)]
pub struct MessageInner {
pub msg: RawMessage,
}
/// Mutators that point to their original message use this to do so.
///
/// Since C++ messages manage their own memory, this can just copy the
/// `RawMessage` instead of referencing an arena like UPB must.
///
/// Note: even though this type is `Copy`, it should only be copied by
/// protobuf internals that can maintain mutation invariants.
#[derive(Clone, Copy, Debug)]
pub struct MutatorMessageRef<'msg> {
msg: RawMessage,
_phantom: PhantomData<&'msg mut ()>,
}
impl<'msg> MutatorMessageRef<'msg> {
#[allow(clippy::needless_pass_by_ref_mut)] // Sound construction requires mutable access.
pub fn new(_private: Private, msg: &'msg mut MessageInner) -> Self {
MutatorMessageRef { msg: msg.msg, _phantom: PhantomData }
}
pub fn msg(&self) -> RawMessage {
self.msg
}
}
pub fn copy_bytes_in_arena_if_needed_by_runtime<'a>(
_msg_ref: MutatorMessageRef<'a>,
val: &'a [u8],
) -> &'a [u8] {
// Nothing to do, the message manages its own string memory for C++.
val
}
#[cfg(test)]
mod tests {
use super::*;
use std::boxed::Box;
// We need to allocate the byte array so SerializedData can own it and
// deallocate it in its drop. This function makes it easier to do so for our
// tests.
fn allocate_byte_array(content: &'static [u8]) -> (*mut u8, usize) {
let content: &mut [u8] = Box::leak(content.into());
(content.as_mut_ptr(), content.len())
}
#[test]
fn test_serialized_data_roundtrip() {
let (ptr, len) = allocate_byte_array(b"Hello world");
let serialized_data = SerializedData { data: NonNull::new(ptr).unwrap(), len: len };
assert_eq!(&*serialized_data, b"Hello world");
}
}