copy in iroh-car from iroh repo, verbatim

1 files changed, 99 insertions, 0 deletions

diff --git a/iroh-car/src/reader.rs b/iroh-car/src/reader.rs
new file mode 100644
index 0000000..c0209be
--- /dev/null
+++ b/iroh-car/src/reader.rs
@@ -0,0 +1,99 @@
+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<R> {
+    reader: R,
+    header: CarHeader,
+    buffer: Vec<u8>,
+}
+
+impl<R> CarReader<R>
+where
+    R: AsyncRead + Send + Unpin,
+{
+    /// Creates a new CarReader and parses the CarHeader
+    pub async fn new(mut reader: R) -> Result<Self, Error> {
+        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<Option<(Cid, Vec<u8>)>, Error> {
+        read_node(&mut self.reader, &mut self.buffer).await
+    }
+
+    pub fn stream(self) -> impl Stream<Item = Result<(Cid, Vec<u8>), 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");
+    }
+}