use cid::Cid; use futures::Stream; use tokio::io::AsyncRead; use crate::{ error::Error, header::CarHeader, util::{ld_read, read_node}, }; /// Reads CAR files that are in a BufReader pub struct CarReader { reader: R, header: CarHeader, buffer: Vec, } impl CarReader where R: AsyncRead + Send + Unpin, { /// Creates a new CarReader and parses the CarHeader pub async fn new(mut reader: R) -> Result { let mut buffer = Vec::new(); match ld_read(&mut reader, &mut buffer).await? { Some(buf) => { let header = CarHeader::decode(buf)?; Ok(CarReader { reader, header, buffer, }) } None => Err(Error::Parsing( "failed to parse uvarint for header".to_string(), )), } } /// Returns the header of this car file. pub fn header(&self) -> &CarHeader { &self.header } /// Returns the next IPLD Block in the buffer pub async fn next_block(&mut self) -> Result)>, Error> { read_node(&mut self.reader, &mut self.buffer).await } pub fn stream(self) -> impl Stream), Error>> { futures::stream::try_unfold(self, |mut this| async move { let maybe_block = read_node(&mut this.reader, &mut this.buffer).await?; Ok(maybe_block.map(|b| (b, this))) }) } } #[cfg(test)] mod tests { use std::io::Cursor; use cid::Cid; use futures::TryStreamExt; use ipld_cbor::DagCborCodec; use multihash::MultihashDigest; use crate::{header::CarHeaderV1, writer::CarWriter}; use super::*; #[tokio::test] async fn car_write_read() { let digest_test = multihash::Code::Blake2b256.digest(b"test"); let cid_test = Cid::new_v1(DagCborCodec.into(), digest_test); let digest_foo = multihash::Code::Blake2b256.digest(b"foo"); let cid_foo = Cid::new_v1(DagCborCodec.into(), digest_foo); let header = CarHeader::V1(CarHeaderV1::from(vec![cid_foo])); let mut buffer = Vec::new(); let mut writer = CarWriter::new(header, &mut buffer); writer.write(cid_test, b"test").await.unwrap(); writer.write(cid_foo, b"foo").await.unwrap(); writer.finish().await.unwrap(); let reader = Cursor::new(&buffer); let car_reader = CarReader::new(reader).await.unwrap(); let files: Vec<_> = car_reader.stream().try_collect().await.unwrap(); assert_eq!(files.len(), 2); assert_eq!(files[0].0, cid_test); assert_eq!(files[0].1, b"test"); assert_eq!(files[1].0, cid_foo); assert_eq!(files[1].1, b"foo"); } }