use super::writer::TOC_MAGIC;
use crate::{
checksum::Checksum,
toc::{entry::TocEntry, Toc},
Result,
};
use byteorder::ReadBytesExt;
use std::io::{Read, Seek, SeekFrom};
struct ChecksummedReader<R: std::io::Read> {
inner: R,
hasher: xxhash_rust::xxh3::Xxh3Default,
}
impl<R: std::io::Read> ChecksummedReader<R> {
pub fn new(reader: R) -> Self {
Self {
inner: reader,
hasher: xxhash_rust::xxh3::Xxh3Default::new(),
}
}
pub fn checksum(&self) -> Checksum {
Checksum::from_raw(self.hasher.digest128())
}
}
impl<R: std::io::Read> std::io::Read for ChecksummedReader<R> {
fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
let n = self.inner.read(buf)?;
#[allow(clippy::indexing_slicing)]
self.hasher.update(&buf[..n]);
Ok(n)
}
}
pub struct TocReader;
impl TocReader {
pub fn from_reader<R: Read + Seek>(
reader: &mut R,
toc_pos: u64,
toc_checksum: Checksum,
) -> Result<Toc> {
use byteorder::LE;
log::trace!("Reading ToC");
reader.seek(SeekFrom::Start(toc_pos))?;
let mut reader = ChecksummedReader::new(reader);
{
let mut buf = [0u8; TOC_MAGIC.len()];
reader.read_exact(&mut buf)?;
if buf != TOC_MAGIC {
log::error!("Invalid version");
return Err(crate::Error::InvalidVersion);
}
}
let len = reader.read_u32::<LE>()?;
let mut entries = Vec::with_capacity(len as usize);
for _ in 0..len {
entries.push(TocEntry::read_from_file(&mut reader)?);
}
reader.checksum().check(toc_checksum)?;
Ok(Toc(entries))
}
}