feat(tvix/nix-compat): introduce write_worker_trust_level r/7844

This is used by the nix client to determine whether or not the daemon
trust it. The trust conditions check are daemon-specific, hence not
part of nix-compat.

Change-Id: Icbcba2f7f1fd58f67e7da72d22a264f5a3f3619d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11231
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

1 files changed, 22 insertions, 0 deletions

diff --git a/tvix/nix-compat/src/wire/worker_protocol.rs b/tvix/nix-compat/src/wire/worker_protocol.rs
index 82f227c723..3d891068ea 100644
--- a/tvix/nix-compat/src/wire/worker_protocol.rs
+++ b/tvix/nix-compat/src/wire/worker_protocol.rs
@@ -81,3 +81,25 @@ pub async fn write_op<W: AsyncWriteExt + Unpin>(w: &mut W, op: &Operation) -> st
     ))?;
     w.write_u64(op).await
 }
+
+#[derive(Debug, PartialEq)]
+pub enum Trust {
+    Trusted,
+    NotTrusted,
+}
+
+/// Write the worker [Trust] level to the wire.
+///
+/// Cpp Nix has a legacy third option: u8 0. This option is meant to
+/// be used as a backward compatible measure. Since we're not
+/// targetting protocol versions pre-dating the trust notion, we
+/// decided not to implement it here.
+pub async fn write_worker_trust_level<W>(conn: &mut W, t: Trust) -> std::io::Result<()>
+where
+    W: AsyncReadExt + AsyncWriteExt + Unpin + std::fmt::Debug,
+{
+    match t {
+        Trust::Trusted => primitive::write_u64(conn, 1).await,
+        Trust::NotTrusted => primitive::write_u64(conn, 2).await,
+    }
+}