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use integer_encoding::VarIntAsyncReader;
use libipld::Cid;
use tokio::io::{AsyncRead, AsyncReadExt};
use super::error::Error;
/// Maximum size that is used for single node.
pub(crate) const MAX_ALLOC: usize = 4 * 1024 * 1024;
pub(crate) async fn ld_read<R>(mut reader: R, buf: &mut Vec<u8>) -> Result<Option<&[u8]>, Error>
where
R: AsyncRead + Send + Unpin,
{
let length: usize = match VarIntAsyncReader::read_varint_async(&mut reader).await {
Ok(len) => len,
Err(e) => {
if e.kind() == std::io::ErrorKind::UnexpectedEof {
return Ok(None);
}
return Err(Error::Parsing(e.to_string()));
}
};
if length > MAX_ALLOC {
return Err(Error::LdReadTooLarge(length));
}
if length > buf.len() {
buf.resize(length, 0);
}
reader
.read_exact(&mut buf[..length])
.await
.map_err(|e| Error::Parsing(e.to_string()))?;
Ok(Some(&buf[..length]))
}
pub(crate) async fn read_node<R>(
buf_reader: &mut R,
buf: &mut Vec<u8>,
) -> Result<Option<(Cid, Vec<u8>)>, Error>
where
R: AsyncRead + Send + Unpin,
{
if let Some(buf) = ld_read(buf_reader, buf).await? {
let mut cursor = std::io::Cursor::new(buf);
let c = Cid::read_bytes(&mut cursor)?;
let pos = cursor.position() as usize;
return Ok(Some((c, buf[pos..].to_vec())));
}
Ok(None)
}
#[cfg(test)]
mod tests {
use integer_encoding::VarIntAsyncWriter;
use tokio::io::{AsyncWrite, AsyncWriteExt};
use super::*;
async fn ld_write<'a, W>(writer: &mut W, bytes: &[u8]) -> Result<(), Error>
where
W: AsyncWrite + Send + Unpin,
{
writer.write_varint_async(bytes.len()).await?;
writer.write_all(bytes).await?;
writer.flush().await?;
Ok(())
}
#[tokio::test]
async fn ld_read_write_good() {
let mut buffer = Vec::<u8>::new();
ld_write(&mut buffer, b"test bytes").await.unwrap();
let reader = std::io::Cursor::new(buffer);
let mut buffer = vec![1u8; 1024];
let read = ld_read(reader, &mut buffer).await.unwrap().unwrap();
assert_eq!(read, b"test bytes");
}
#[tokio::test]
async fn ld_read_write_fail() {
let mut buffer = Vec::<u8>::new();
let size = MAX_ALLOC + 1;
ld_write(&mut buffer, &vec![2u8; size]).await.unwrap();
let reader = std::io::Cursor::new(buffer);
let mut buffer = vec![1u8; 1024];
let read = ld_read(reader, &mut buffer).await;
assert!(matches!(read, Err(Error::LdReadTooLarge(_))));
}
}
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