feat(tvix/nix-compat): Add nix serialization support r/8893

This change implements the serialization part that is needed to
implement the nix daemon protocol. Previously was add deserialization
and derivers for that and this then adds the other part of that equation
so that you can write types that can then be read using deserialization.

Change-Id: I2917de634980a93822a4f5a8ad38897b9ce16d89
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12729
Autosubmit: Brian Olsen <me@griff.name>
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

1 files changed, 89 insertions, 0 deletions

diff --git a/tvix/nix-compat/src/nix_daemon/ser/bytes.rs b/tvix/nix-compat/src/nix_daemon/ser/bytes.rs
new file mode 100644
index 000000000000..19494934ff32
--- /dev/null
+++ b/tvix/nix-compat/src/nix_daemon/ser/bytes.rs
@@ -0,0 +1,89 @@
+use bytes::Bytes;
+
+use super::{NixSerialize, NixWrite};
+
+impl NixSerialize for Bytes {
+    async fn serialize<W>(&self, writer: &mut W) -> Result<(), W::Error>
+    where
+        W: NixWrite,
+    {
+        writer.write_slice(self).await
+    }
+}
+
+impl<'a> NixSerialize for &'a [u8] {
+    async fn serialize<W>(&self, writer: &mut W) -> Result<(), W::Error>
+    where
+        W: NixWrite,
+    {
+        writer.write_slice(self).await
+    }
+}
+
+impl NixSerialize for String {
+    async fn serialize<W>(&self, writer: &mut W) -> Result<(), W::Error>
+    where
+        W: NixWrite,
+    {
+        writer.write_slice(self.as_bytes()).await
+    }
+}
+
+impl NixSerialize for str {
+    async fn serialize<W>(&self, writer: &mut W) -> Result<(), W::Error>
+    where
+        W: NixWrite,
+    {
+        writer.write_slice(self.as_bytes()).await
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use hex_literal::hex;
+    use rstest::rstest;
+    use tokio::io::AsyncWriteExt as _;
+    use tokio_test::io::Builder;
+
+    use crate::nix_daemon::ser::{NixWrite, NixWriter};
+
+    #[rstest]
+    #[case::empty("", &hex!("0000 0000 0000 0000"))]
+    #[case::one(")", &hex!("0100 0000 0000 0000 2900 0000 0000 0000"))]
+    #[case::two("it", &hex!("0200 0000 0000 0000 6974 0000 0000 0000"))]
+    #[case::three("tea", &hex!("0300 0000 0000 0000 7465 6100 0000 0000"))]
+    #[case::four("were", &hex!("0400 0000 0000 0000 7765 7265 0000 0000"))]
+    #[case::five("where", &hex!("0500 0000 0000 0000 7768 6572 6500 0000"))]
+    #[case::six("unwrap", &hex!("0600 0000 0000 0000 756E 7772 6170 0000"))]
+    #[case::seven("where's", &hex!("0700 0000 0000 0000 7768 6572 6527 7300"))]
+    #[case::aligned("read_tea", &hex!("0800 0000 0000 0000 7265 6164 5F74 6561"))]
+    #[case::more_bytes("read_tess", &hex!("0900 0000 0000 0000 7265 6164 5F74 6573 7300 0000 0000 0000"))]
+    #[case::utf8("The quick brown 🦊 jumps over 13 lazy 🐶.", &hex!("2D00 0000 0000 0000  5468 6520 7175 6963  6b20 6272 6f77 6e20  f09f a68a 206a 756d  7073 206f 7665 7220  3133 206c 617a 7920  f09f 90b6 2e00 0000"))]
+    #[tokio::test]
+    async fn test_write_str(#[case] value: &str, #[case] data: &[u8]) {
+        let mock = Builder::new().write(data).build();
+        let mut writer = NixWriter::new(mock);
+        writer.write_value(value).await.unwrap();
+        writer.flush().await.unwrap();
+    }
+
+    #[rstest]
+    #[case::empty("", &hex!("0000 0000 0000 0000"))]
+    #[case::one(")", &hex!("0100 0000 0000 0000 2900 0000 0000 0000"))]
+    #[case::two("it", &hex!("0200 0000 0000 0000 6974 0000 0000 0000"))]
+    #[case::three("tea", &hex!("0300 0000 0000 0000 7465 6100 0000 0000"))]
+    #[case::four("were", &hex!("0400 0000 0000 0000 7765 7265 0000 0000"))]
+    #[case::five("where", &hex!("0500 0000 0000 0000 7768 6572 6500 0000"))]
+    #[case::six("unwrap", &hex!("0600 0000 0000 0000 756E 7772 6170 0000"))]
+    #[case::seven("where's", &hex!("0700 0000 0000 0000 7768 6572 6527 7300"))]
+    #[case::aligned("read_tea", &hex!("0800 0000 0000 0000 7265 6164 5F74 6561"))]
+    #[case::more_bytes("read_tess", &hex!("0900 0000 0000 0000 7265 6164 5F74 6573 7300 0000 0000 0000"))]
+    #[case::utf8("The quick brown 🦊 jumps over 13 lazy 🐶.", &hex!("2D00 0000 0000 0000  5468 6520 7175 6963  6b20 6272 6f77 6e20  f09f a68a 206a 756d  7073 206f 7665 7220  3133 206c 617a 7920  f09f 90b6 2e00 0000"))]
+    #[tokio::test]
+    async fn test_write_string(#[case] value: &str, #[case] data: &[u8]) {
+        let mock = Builder::new().write(data).build();
+        let mut writer = NixWriter::new(mock);
+        writer.write_value(&value.to_string()).await.unwrap();
+        writer.flush().await.unwrap();
+    }
+}