refactor(tvix/store): use strictly typed PathInfo struct r/8787

This switches the PathInfoService trait from using the proto-derived
PathInfo struct to a more restrictive struct, and updates all
implementations to use it.

It removes a lot of the previous conversion and checks, as invalid
states became nonrepresentable, and validations are expressed on the
type level.

PathInfoService implementations consuming protobuf need to convert and
do the verification internally, and can only return the strongly typed
variant.

The nix_compat::narinfo::NarInfo conversions for the proto PathInfo
are removed, we only keep a version showing a NarInfo representation for
the strong struct.

Converting back to a PathInfo requires the root node now, but is
otherwise trivial, so left to the users.

Co-Authored-By: Florian Klink <flokli@flokli.de>
Change-Id: I6fdfdb44063efebb44a8f0097b6b81a828717e03
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12588
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

1 files changed, 29 insertions, 0 deletions

diff --git a/tvix/castore/src/proto/tests/mod.rs b/tvix/castore/src/proto/tests/mod.rs
index 74334029e84c..8efb92870374 100644
--- a/tvix/castore/src/proto/tests/mod.rs
+++ b/tvix/castore/src/proto/tests/mod.rs
@@ -1 +1,30 @@
+use super::{node, Node, SymlinkNode};
+
 mod directory;
+
+/// Create a node with an empty symlink target, and ensure it fails validation.
+#[test]
+fn convert_symlink_empty_target_invalid() {
+    Node {
+        node: Some(node::Node::Symlink(SymlinkNode {
+            name: "foo".into(),
+            target: "".into(),
+        })),
+    }
+    .into_name_and_node()
+    .expect_err("must fail validation");
+}
+
+/// Create a node with a symlink target including null bytes, and ensure it
+/// fails validation.
+#[test]
+fn convert_symlink_target_null_byte_invalid() {
+    Node {
+        node: Some(node::Node::Symlink(SymlinkNode {
+            name: "foo".into(),
+            target: "foo\0".into(),
+        })),
+    }
+    .into_name_and_node()
+    .expect_err("must fail validation");
+}