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|
use error::Result;
use serde;
use std::{io, slice};
/// An optional Read trait for advanced Bincode usage.
///
/// It is highly recommended to use bincode with `io::Read` or `&[u8]` before
/// implementing a custom `BincodeRead`.
pub trait BincodeRead<'storage>: io::Read {
/// Forwards reading `length` bytes of a string on to the serde reader.
fn forward_read_str<V>(&mut self, length: usize, visitor: V) -> Result<V::Value>
where
V: serde::de::Visitor<'storage>;
/// Return the first `length` bytes of the internal byte buffer.
fn get_byte_buffer(&mut self, length: usize) -> Result<Vec<u8>>;
/// Forwards reading `length` bytes on to the serde reader.
fn forward_read_bytes<V>(&mut self, length: usize, visitor: V) -> Result<V::Value>
where
V: serde::de::Visitor<'storage>;
}
/// A BincodeRead implementation for byte slices
/// NOT A PART OF THE STABLE PUBLIC API
#[doc(hidden)]
pub struct SliceReader<'storage> {
slice: &'storage [u8],
}
/// A BincodeRead implementation for io::Readers
/// NOT A PART OF THE STABLE PUBLIC API
#[doc(hidden)]
pub struct IoReader<R> {
reader: R,
temp_buffer: Vec<u8>,
}
impl<'storage> SliceReader<'storage> {
/// Constructs a slice reader
pub fn new(bytes: &'storage [u8]) -> SliceReader<'storage> {
SliceReader { slice: bytes }
}
}
impl<R> IoReader<R> {
/// Constructs an IoReadReader
pub fn new(r: R) -> IoReader<R> {
IoReader {
reader: r,
temp_buffer: vec![],
}
}
}
impl<'storage> io::Read for SliceReader<'storage> {
#[inline(always)]
fn read(&mut self, out: &mut [u8]) -> io::Result<usize> {
(&mut self.slice).read(out)
}
#[inline(always)]
fn read_exact(&mut self, out: &mut [u8]) -> io::Result<()> {
(&mut self.slice).read_exact(out)
}
}
impl<R: io::Read> io::Read for IoReader<R> {
#[inline(always)]
fn read(&mut self, out: &mut [u8]) -> io::Result<usize> {
self.reader.read(out)
}
#[inline(always)]
fn read_exact(&mut self, out: &mut [u8]) -> io::Result<()> {
self.reader.read_exact(out)
}
}
impl<'storage> SliceReader<'storage> {
#[inline(always)]
fn unexpected_eof() -> Box<::ErrorKind> {
return Box::new(::ErrorKind::Io(io::Error::new(
io::ErrorKind::UnexpectedEof,
"",
)));
}
}
impl<'storage> BincodeRead<'storage> for SliceReader<'storage> {
#[inline(always)]
fn forward_read_str<V>(&mut self, length: usize, visitor: V) -> Result<V::Value>
where
V: serde::de::Visitor<'storage>,
{
use ErrorKind;
if length > self.slice.len() {
return Err(SliceReader::unexpected_eof());
}
let string = match ::std::str::from_utf8(&self.slice[..length]) {
Ok(s) => s,
Err(e) => return Err(ErrorKind::InvalidUtf8Encoding(e).into()),
};
let r = visitor.visit_borrowed_str(string);
self.slice = &self.slice[length..];
r
}
#[inline(always)]
fn get_byte_buffer(&mut self, length: usize) -> Result<Vec<u8>> {
if length > self.slice.len() {
return Err(SliceReader::unexpected_eof());
}
let r = &self.slice[..length];
self.slice = &self.slice[length..];
Ok(r.to_vec())
}
#[inline(always)]
fn forward_read_bytes<V>(&mut self, length: usize, visitor: V) -> Result<V::Value>
where
V: serde::de::Visitor<'storage>,
{
if length > self.slice.len() {
return Err(SliceReader::unexpected_eof());
}
let r = visitor.visit_borrowed_bytes(&self.slice[..length]);
self.slice = &self.slice[length..];
r
}
}
impl<R> IoReader<R>
where
R: io::Read,
{
fn fill_buffer(&mut self, length: usize) -> Result<()> {
// We first reserve the space needed in our buffer.
let current_length = self.temp_buffer.len();
if length > current_length {
self.temp_buffer.reserve_exact(length - current_length);
}
// Then create a slice with the length as our desired length. This is
// safe as long as we only write (no reads) to this buffer, because
// `reserve_exact` above has allocated this space.
let buf = unsafe {
slice::from_raw_parts_mut(self.temp_buffer.as_mut_ptr(), length)
};
// This method is assumed to properly handle slices which include
// uninitialized bytes (as ours does). See discussion at the link below.
// https://github.com/servo/bincode/issues/260
self.reader.read_exact(buf)?;
// Only after `read_exact` successfully returns do we set the buffer
// length. By doing this after the call to `read_exact`, we can avoid
// exposing uninitialized memory in the case of `read_exact` returning
// an error.
unsafe {
self.temp_buffer.set_len(length);
}
Ok(())
}
}
impl<'a, R> BincodeRead<'a> for IoReader<R>
where
R: io::Read,
{
fn forward_read_str<V>(&mut self, length: usize, visitor: V) -> Result<V::Value>
where
V: serde::de::Visitor<'a>,
{
self.fill_buffer(length)?;
let string = match ::std::str::from_utf8(&self.temp_buffer[..]) {
Ok(s) => s,
Err(e) => return Err(::ErrorKind::InvalidUtf8Encoding(e).into()),
};
let r = visitor.visit_str(string);
r
}
fn get_byte_buffer(&mut self, length: usize) -> Result<Vec<u8>> {
self.fill_buffer(length)?;
Ok(::std::mem::replace(&mut self.temp_buffer, Vec::new()))
}
fn forward_read_bytes<V>(&mut self, length: usize, visitor: V) -> Result<V::Value>
where
V: serde::de::Visitor<'a>,
{
self.fill_buffer(length)?;
let r = visitor.visit_bytes(&self.temp_buffer[..]);
r
}
}
|
