refactor(tvix/castore): use Directory struct separate from proto one r/8484

This uses our own data type to deal with Directories in the castore model.

It makes some undesired states unrepresentable, removing the need for conversions and checking in various places:

 - In the protobuf, blake3 digests could have a wrong length, as proto doesn't know fixed-size fields. We now use `B3Digest`, which makes cloning cheaper, and removes the need to do size-checking everywhere.
 - In the protobuf, we had three different lists for `files`, `symlinks` and `directories`. This was mostly a protobuf size optimization, but made interacting with them a bit awkward. This has now been replaced with a list of enums, and convenience iterators to get various nodes, and add new ones.

Change-Id: I7b92691bb06d77ff3f58a5ccea94a22c16f84f04
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12057
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>

5 files changed, 215 insertions, 567 deletions

diff --git a/tvix/castore/src/proto/grpc_directoryservice_wrapper.rs b/tvix/castore/src/proto/grpc_directoryservice_wrapper.rs
index ce1d2bcd244a..e65145509184 100644
--- a/tvix/castore/src/proto/grpc_directoryservice_wrapper.rs
+++ b/tvix/castore/src/proto/grpc_directoryservice_wrapper.rs
@@ -1,7 +1,5 @@
-use crate::directoryservice::DirectoryGraph;
-use crate::directoryservice::LeavesToRootValidator;
-use crate::proto;
-use crate::{directoryservice::DirectoryService, B3Digest};
+use crate::directoryservice::{DirectoryGraph, DirectoryService, LeavesToRootValidator};
+use crate::{proto, B3Digest, ValidateDirectoryError};
 use futures::stream::BoxStream;
 use futures::TryStreamExt;
 use std::ops::Deref;
@@ -58,13 +56,16 @@ where
                                 Status::not_found(format!("directory {} not found", digest))
                             })?;
 
-                        Box::pin(once(Ok(directory)))
+                        Box::pin(once(Ok(directory.into())))
                     } else {
                         // If recursive was requested, traverse via get_recursive.
                         Box::pin(
-                            self.directory_service.get_recursive(&digest).map_err(|e| {
-                                tonic::Status::new(tonic::Code::Internal, e.to_string())
-                            }),
+                            self.directory_service
+                                .get_recursive(&digest)
+                                .map_ok(proto::Directory::from)
+                                .map_err(|e| {
+                                    tonic::Status::new(tonic::Code::Internal, e.to_string())
+                                }),
                         )
                     }
                 }))
@@ -83,7 +84,9 @@ where
         let mut validator = DirectoryGraph::<LeavesToRootValidator>::default();
         while let Some(directory) = req_inner.message().await? {
             validator
-                .add(directory)
+                .add(directory.try_into().map_err(|e: ValidateDirectoryError| {
+                    tonic::Status::new(tonic::Code::Internal, e.to_string())
+                })?)
                 .map_err(|e| tonic::Status::new(tonic::Code::Internal, e.to_string()))?;
         }
 
diff --git a/tvix/castore/src/proto/mod.rs b/tvix/castore/src/proto/mod.rs
index a0cec896f753..7e98cd74c591 100644
--- a/tvix/castore/src/proto/mod.rs
+++ b/tvix/castore/src/proto/mod.rs
@@ -1,7 +1,4 @@
-#![allow(non_snake_case)]
-// https://github.com/hyperium/tonic/issues/1056
-use bstr::ByteSlice;
-use std::{collections::HashSet, iter::Peekable, str};
+use std::str;
 
 use prost::Message;
 
@@ -11,7 +8,8 @@ mod grpc_directoryservice_wrapper;
 pub use grpc_blobservice_wrapper::GRPCBlobServiceWrapper;
 pub use grpc_directoryservice_wrapper::GRPCDirectoryServiceWrapper;
 
-use crate::{B3Digest, B3_LEN};
+use crate::directoryservice::NamedNode;
+use crate::{B3Digest, ValidateDirectoryError, ValidateNodeError};
 
 tonic::include_proto!("tvix.castore.v1");
 
@@ -24,38 +22,6 @@ pub const FILE_DESCRIPTOR_SET: &[u8] = tonic::include_file_descriptor_set!("tvix
 #[cfg(test)]
 mod tests;
 
-/// Errors that can occur during the validation of [Directory] messages.
-#[derive(Debug, PartialEq, Eq, thiserror::Error)]
-pub enum ValidateDirectoryError {
-    /// Elements are not in sorted order
-    #[error("{:?} is not sorted", .0.as_bstr())]
-    WrongSorting(Vec<u8>),
-    /// Multiple elements with the same name encountered
-    #[error("{:?} is a duplicate name", .0.as_bstr())]
-    DuplicateName(Vec<u8>),
-    /// Invalid node
-    #[error("invalid node with name {:?}: {:?}", .0.as_bstr(), .1.to_string())]
-    InvalidNode(Vec<u8>, ValidateNodeError),
-    #[error("Total size exceeds u32::MAX")]
-    SizeOverflow,
-}
-
-/// Errors that occur during Node validation
-#[derive(Debug, PartialEq, Eq, thiserror::Error)]
-pub enum ValidateNodeError {
-    #[error("No node set")]
-    NoNodeSet,
-    /// Invalid digest length encountered
-    #[error("Invalid Digest length: {0}")]
-    InvalidDigestLen(usize),
-    /// Invalid name encountered
-    #[error("Invalid name: {}", .0.as_bstr())]
-    InvalidName(Vec<u8>),
-    /// Invalid symlink target
-    #[error("Invalid symlink target: {}", .0.as_bstr())]
-    InvalidSymlinkTarget(Vec<u8>),
-}
-
 /// Errors that occur during StatBlobResponse validation
 #[derive(Debug, PartialEq, Eq, thiserror::Error)]
 pub enum ValidateStatBlobResponseError {
@@ -64,186 +30,6 @@ pub enum ValidateStatBlobResponseError {
     InvalidDigestLen(usize, usize),
 }
 
-/// Checks a Node name for validity as an intermediate node.
-/// We disallow slashes, null bytes, '.', '..' and the empty string.
-pub(crate) fn validate_node_name(name: &[u8]) -> Result<(), ValidateNodeError> {
-    if name.is_empty()
-        || name == b".."
-        || name == b"."
-        || name.contains(&0x00)
-        || name.contains(&b'/')
-    {
-        Err(ValidateNodeError::InvalidName(name.to_owned()))
-    } else {
-        Ok(())
-    }
-}
-
-/// NamedNode is implemented for [FileNode], [DirectoryNode] and [SymlinkNode]
-/// and [node::Node], so we can ask all of them for the name easily.
-pub trait NamedNode {
-    fn get_name(&self) -> &[u8];
-}
-
-impl NamedNode for &FileNode {
-    fn get_name(&self) -> &[u8] {
-        &self.name
-    }
-}
-
-impl NamedNode for &DirectoryNode {
-    fn get_name(&self) -> &[u8] {
-        &self.name
-    }
-}
-
-impl NamedNode for &SymlinkNode {
-    fn get_name(&self) -> &[u8] {
-        &self.name
-    }
-}
-
-impl NamedNode for node::Node {
-    fn get_name(&self) -> &[u8] {
-        match self {
-            node::Node::File(node_file) => &node_file.name,
-            node::Node::Directory(node_directory) => &node_directory.name,
-            node::Node::Symlink(node_symlink) => &node_symlink.name,
-        }
-    }
-}
-
-impl Node {
-    /// Ensures the node has a valid enum kind (is Some), and passes its
-    // per-enum validation.
-    // The inner root node is returned for easier consumption.
-    pub fn validate(&self) -> Result<&node::Node, ValidateNodeError> {
-        if let Some(node) = self.node.as_ref() {
-            node.validate()?;
-            Ok(node)
-        } else {
-            Err(ValidateNodeError::NoNodeSet)
-        }
-    }
-}
-
-impl node::Node {
-    /// Returns the node with a new name.
-    pub fn rename(self, name: bytes::Bytes) -> Self {
-        match self {
-            node::Node::Directory(n) => node::Node::Directory(DirectoryNode { name, ..n }),
-            node::Node::File(n) => node::Node::File(FileNode { name, ..n }),
-            node::Node::Symlink(n) => node::Node::Symlink(SymlinkNode { name, ..n }),
-        }
-    }
-
-    /// Ensures the node has a valid name, and checks the type-specific fields too.
-    pub fn validate(&self) -> Result<(), ValidateNodeError> {
-        match self {
-            // for a directory root node, ensure the digest has the appropriate size.
-            node::Node::Directory(directory_node) => {
-                if directory_node.digest.len() != B3_LEN {
-                    Err(ValidateNodeError::InvalidDigestLen(
-                        directory_node.digest.len(),
-                    ))?;
-                }
-                validate_node_name(&directory_node.name)
-            }
-            // for a file root node, ensure the digest has the appropriate size.
-            node::Node::File(file_node) => {
-                if file_node.digest.len() != B3_LEN {
-                    Err(ValidateNodeError::InvalidDigestLen(file_node.digest.len()))?;
-                }
-                validate_node_name(&file_node.name)
-            }
-            // ensure the symlink target is not empty and doesn't contain null bytes.
-            node::Node::Symlink(symlink_node) => {
-                if symlink_node.target.is_empty() || symlink_node.target.contains(&b'\0') {
-                    Err(ValidateNodeError::InvalidSymlinkTarget(
-                        symlink_node.target.to_vec(),
-                    ))?;
-                }
-                validate_node_name(&symlink_node.name)
-            }
-        }
-    }
-}
-
-impl PartialOrd for node::Node {
-    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-impl Ord for node::Node {
-    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
-        self.get_name().cmp(other.get_name())
-    }
-}
-
-impl PartialOrd for FileNode {
-    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-impl Ord for FileNode {
-    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
-        self.get_name().cmp(other.get_name())
-    }
-}
-
-impl PartialOrd for SymlinkNode {
-    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-impl Ord for SymlinkNode {
-    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
-        self.get_name().cmp(other.get_name())
-    }
-}
-
-impl PartialOrd for DirectoryNode {
-    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-impl Ord for DirectoryNode {
-    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
-        self.get_name().cmp(other.get_name())
-    }
-}
-
-/// Accepts a name, and a mutable reference to the previous name.
-/// If the passed name is larger than the previous one, the reference is updated.
-/// If it's not, an error is returned.
-fn update_if_lt_prev<'n>(
-    prev_name: &mut &'n [u8],
-    name: &'n [u8],
-) -> Result<(), ValidateDirectoryError> {
-    if *name < **prev_name {
-        return Err(ValidateDirectoryError::WrongSorting(name.to_vec()));
-    }
-    *prev_name = name;
-    Ok(())
-}
-
-/// Inserts the given name into a HashSet if it's not already in there.
-/// If it is, an error is returned.
-fn insert_once<'n>(
-    seen_names: &mut HashSet<&'n [u8]>,
-    name: &'n [u8],
-) -> Result<(), ValidateDirectoryError> {
-    if seen_names.get(name).is_some() {
-        return Err(ValidateDirectoryError::DuplicateName(name.to_vec()));
-    }
-    seen_names.insert(name);
-    Ok(())
-}
-
 fn checked_sum(iter: impl IntoIterator<Item = u64>) -> Option<u64> {
     iter.into_iter().try_fold(0u64, |acc, i| acc.checked_add(i))
 }
@@ -280,116 +66,213 @@ impl Directory {
             .as_bytes()
             .into()
     }
+}
+
+/// Accepts a name, and a mutable reference to the previous name.
+/// If the passed name is larger than the previous one, the reference is updated.
+/// If it's not, an error is returned.
+fn update_if_lt_prev<'n>(
+    prev_name: &mut &'n [u8],
+    name: &'n [u8],
+) -> Result<(), ValidateDirectoryError> {
+    if *name < **prev_name {
+        return Err(ValidateDirectoryError::WrongSorting(name.to_vec()));
+    }
+    *prev_name = name;
+    Ok(())
+}
 
-    /// validate checks the directory for invalid data, such as:
-    /// - violations of name restrictions
-    /// - invalid digest lengths
-    /// - not properly sorted lists
-    /// - duplicate names in the three lists
-    pub fn validate(&self) -> Result<(), ValidateDirectoryError> {
-        let mut seen_names: HashSet<&[u8]> = HashSet::new();
+impl TryFrom<&node::Node> for crate::directoryservice::Node {
+    type Error = ValidateNodeError;
 
-        let mut last_directory_name: &[u8] = b"";
-        let mut last_file_name: &[u8] = b"";
-        let mut last_symlink_name: &[u8] = b"";
+    fn try_from(node: &node::Node) -> Result<crate::directoryservice::Node, ValidateNodeError> {
+        Ok(match node {
+            node::Node::Directory(n) => crate::directoryservice::Node::Directory(n.try_into()?),
+            node::Node::File(n) => crate::directoryservice::Node::File(n.try_into()?),
+            node::Node::Symlink(n) => crate::directoryservice::Node::Symlink(n.try_into()?),
+        })
+    }
+}
 
-        // check directories
-        for directory_node in &self.directories {
-            node::Node::Directory(directory_node.clone())
-                .validate()
-                .map_err(|e| {
-                    ValidateDirectoryError::InvalidNode(directory_node.name.to_vec(), e)
-                })?;
+impl TryFrom<&Node> for crate::directoryservice::Node {
+    type Error = ValidateNodeError;
 
-            update_if_lt_prev(&mut last_directory_name, &directory_node.name)?;
-            insert_once(&mut seen_names, &directory_node.name)?;
+    fn try_from(node: &Node) -> Result<crate::directoryservice::Node, ValidateNodeError> {
+        match node {
+            Node { node: None } => Err(ValidateNodeError::NoNodeSet),
+            Node { node: Some(node) } => node.try_into(),
         }
+    }
+}
+
+impl TryFrom<&DirectoryNode> for crate::directoryservice::DirectoryNode {
+    type Error = ValidateNodeError;
+
+    fn try_from(
+        node: &DirectoryNode,
+    ) -> Result<crate::directoryservice::DirectoryNode, ValidateNodeError> {
+        crate::directoryservice::DirectoryNode::new(
+            node.name.clone(),
+            node.digest.clone().try_into()?,
+            node.size,
+        )
+    }
+}
 
-        // check files
-        for file_node in &self.files {
-            node::Node::File(file_node.clone())
-                .validate()
-                .map_err(|e| ValidateDirectoryError::InvalidNode(file_node.name.to_vec(), e))?;
+impl TryFrom<&SymlinkNode> for crate::directoryservice::SymlinkNode {
+    type Error = ValidateNodeError;
 
-            update_if_lt_prev(&mut last_file_name, &file_node.name)?;
-            insert_once(&mut seen_names, &file_node.name)?;
+    fn try_from(
+        node: &SymlinkNode,
+    ) -> Result<crate::directoryservice::SymlinkNode, ValidateNodeError> {
+        crate::directoryservice::SymlinkNode::new(node.name.clone(), node.target.clone())
+    }
+}
+
+impl TryFrom<&FileNode> for crate::directoryservice::FileNode {
+    type Error = ValidateNodeError;
+
+    fn try_from(node: &FileNode) -> Result<crate::directoryservice::FileNode, ValidateNodeError> {
+        crate::directoryservice::FileNode::new(
+            node.name.clone(),
+            node.digest.clone().try_into()?,
+            node.size,
+            node.executable,
+        )
+    }
+}
+
+impl TryFrom<Directory> for crate::directoryservice::Directory {
+    type Error = ValidateDirectoryError;
+
+    fn try_from(
+        directory: Directory,
+    ) -> Result<crate::directoryservice::Directory, ValidateDirectoryError> {
+        (&directory).try_into()
+    }
+}
+
+impl TryFrom<&Directory> for crate::directoryservice::Directory {
+    type Error = ValidateDirectoryError;
+
+    fn try_from(
+        directory: &Directory,
+    ) -> Result<crate::directoryservice::Directory, ValidateDirectoryError> {
+        let mut dir = crate::directoryservice::Directory::new();
+        let mut last_file_name: &[u8] = b"";
+        for file in directory.files.iter().map(move |file| {
+            update_if_lt_prev(&mut last_file_name, &file.name).map(|()| file.clone())
+        }) {
+            let file = file?;
+            dir.add(crate::directoryservice::Node::File(
+                (&file)
+                    .try_into()
+                    .map_err(|e| ValidateDirectoryError::InvalidNode(file.name.into(), e))?,
+            ))?;
+        }
+        let mut last_directory_name: &[u8] = b"";
+        for directory in directory.directories.iter().map(move |directory| {
+            update_if_lt_prev(&mut last_directory_name, &directory.name).map(|()| directory.clone())
+        }) {
+            let directory = directory?;
+            dir.add(crate::directoryservice::Node::Directory(
+                (&directory)
+                    .try_into()
+                    .map_err(|e| ValidateDirectoryError::InvalidNode(directory.name.into(), e))?,
+            ))?;
         }
+        let mut last_symlink_name: &[u8] = b"";
+        for symlink in directory.symlinks.iter().map(move |symlink| {
+            update_if_lt_prev(&mut last_symlink_name, &symlink.name).map(|()| symlink.clone())
+        }) {
+            let symlink = symlink?;
+            dir.add(crate::directoryservice::Node::Symlink(
+                (&symlink)
+                    .try_into()
+                    .map_err(|e| ValidateDirectoryError::InvalidNode(symlink.name.into(), e))?,
+            ))?;
+        }
+        Ok(dir)
+    }
+}
 
-        // check symlinks
-        for symlink_node in &self.symlinks {
-            node::Node::Symlink(symlink_node.clone())
-                .validate()
-                .map_err(|e| ValidateDirectoryError::InvalidNode(symlink_node.name.to_vec(), e))?;
+impl From<&crate::directoryservice::Node> for node::Node {
+    fn from(node: &crate::directoryservice::Node) -> node::Node {
+        match node {
+            crate::directoryservice::Node::Directory(n) => node::Node::Directory(n.into()),
+            crate::directoryservice::Node::File(n) => node::Node::File(n.into()),
+            crate::directoryservice::Node::Symlink(n) => node::Node::Symlink(n.into()),
+        }
+    }
+}
 
-            update_if_lt_prev(&mut last_symlink_name, &symlink_node.name)?;
-            insert_once(&mut seen_names, &symlink_node.name)?;
+impl From<&crate::directoryservice::Node> for Node {
+    fn from(node: &crate::directoryservice::Node) -> Node {
+        Node {
+            node: Some(node.into()),
         }
+    }
+}
 
-        self.size_checked()
-            .ok_or(ValidateDirectoryError::SizeOverflow)?;
+impl From<&crate::directoryservice::DirectoryNode> for DirectoryNode {
+    fn from(node: &crate::directoryservice::DirectoryNode) -> DirectoryNode {
+        DirectoryNode {
+            digest: node.digest().clone().into(),
+            size: node.size(),
+            name: node.get_name().clone(),
+        }
+    }
+}
 
-        Ok(())
+impl From<&crate::directoryservice::FileNode> for FileNode {
+    fn from(node: &crate::directoryservice::FileNode) -> FileNode {
+        FileNode {
+            digest: node.digest().clone().into(),
+            size: node.size(),
+            name: node.get_name().clone(),
+            executable: node.executable(),
+        }
     }
+}
 
-    /// Allows iterating over all three nodes ([DirectoryNode], [FileNode],
-    /// [SymlinkNode]) in an ordered fashion, as long as the individual lists
-    /// are sorted (which can be checked by the [Directory::validate]).
-    pub fn nodes(&self) -> DirectoryNodesIterator {
-        return DirectoryNodesIterator {
-            i_directories: self.directories.iter().peekable(),
-            i_files: self.files.iter().peekable(),
-            i_symlinks: self.symlinks.iter().peekable(),
-        };
+impl From<&crate::directoryservice::SymlinkNode> for SymlinkNode {
+    fn from(node: &crate::directoryservice::SymlinkNode) -> SymlinkNode {
+        SymlinkNode {
+            name: node.get_name().clone(),
+            target: node.target().clone(),
+        }
     }
+}
 
-    /// Adds the specified [node::Node] to the [Directory], preserving sorted entries.
-    /// This assumes the [Directory] to be sorted prior to adding the node.
-    ///
-    /// Inserting an element that already exists with the same name in the directory is not
-    /// supported.
-    pub fn add(&mut self, node: node::Node) {
-        debug_assert!(
-            !self.files.iter().any(|x| x.get_name() == node.get_name()),
-            "name already exists in files"
-        );
-        debug_assert!(
-            !self
-                .directories
-                .iter()
-                .any(|x| x.get_name() == node.get_name()),
-            "name already exists in directories"
-        );
-        debug_assert!(
-            !self
-                .symlinks
-                .iter()
-                .any(|x| x.get_name() == node.get_name()),
-            "name already exists in symlinks"
-        );
+impl From<crate::directoryservice::Directory> for Directory {
+    fn from(directory: crate::directoryservice::Directory) -> Directory {
+        (&directory).into()
+    }
+}
 
-        match node {
-            node::Node::File(node) => {
-                let pos = self
-                    .files
-                    .binary_search(&node)
-                    .expect_err("Tvix bug: dir entry with name already exists");
-                self.files.insert(pos, node);
-            }
-            node::Node::Directory(node) => {
-                let pos = self
-                    .directories
-                    .binary_search(&node)
-                    .expect_err("Tvix bug: dir entry with name already exists");
-                self.directories.insert(pos, node);
-            }
-            node::Node::Symlink(node) => {
-                let pos = self
-                    .symlinks
-                    .binary_search(&node)
-                    .expect_err("Tvix bug: dir entry with name already exists");
-                self.symlinks.insert(pos, node);
+impl From<&crate::directoryservice::Directory> for Directory {
+    fn from(directory: &crate::directoryservice::Directory) -> Directory {
+        let mut directories = vec![];
+        let mut files = vec![];
+        let mut symlinks = vec![];
+        for node in directory.nodes() {
+            match node {
+                crate::directoryservice::Node::File(n) => {
+                    files.push(n.into());
+                }
+                crate::directoryservice::Node::Directory(n) => {
+                    directories.push(n.into());
+                }
+                crate::directoryservice::Node::Symlink(n) => {
+                    symlinks.push(n.into());
+                }
             }
         }
+        Directory {
+            directories,
+            files,
+            symlinks,
+        }
     }
 }
 
@@ -409,65 +292,3 @@ impl StatBlobResponse {
         Ok(())
     }
 }
-
-/// Struct to hold the state of an iterator over all nodes of a Directory.
-///
-/// Internally, this keeps peekable Iterators over all three lists of a
-/// Directory message.
-pub struct DirectoryNodesIterator<'a> {
-    // directory: &Directory,
-    i_directories: Peekable<std::slice::Iter<'a, DirectoryNode>>,
-    i_files: Peekable<std::slice::Iter<'a, FileNode>>,
-    i_symlinks: Peekable<std::slice::Iter<'a, SymlinkNode>>,
-}
-
-/// looks at two elements implementing NamedNode, and returns true if "left
-/// is smaller / comes first".
-///
-/// Some(_) is preferred over None.
-fn left_name_lt_right<A: NamedNode, B: NamedNode>(left: Option<&A>, right: Option<&B>) -> bool {
-    match left {
-        // if left is None, right always wins
-        None => false,
-        Some(left_inner) => {
-            // left is Some.
-            match right {
-                // left is Some, right is None - left wins.
-                None => true,
-                Some(right_inner) => {
-                    // both are Some - compare the name.
-                    return left_inner.get_name() < right_inner.get_name();
-                }
-            }
-        }
-    }
-}
-
-impl Iterator for DirectoryNodesIterator<'_> {
-    type Item = node::Node;
-
-    // next returns the next node in the Directory.
-    // we peek at all three internal iterators, and pick the one with the
-    // smallest name, to ensure lexicographical ordering.
-    // The individual lists are already known to be sorted.
-    fn next(&mut self) -> Option<Self::Item> {
-        if left_name_lt_right(self.i_directories.peek(), self.i_files.peek()) {
-            // i_directories is still in the game, compare with symlinks
-            if left_name_lt_right(self.i_directories.peek(), self.i_symlinks.peek()) {
-                self.i_directories
-                    .next()
-                    .cloned()
-                    .map(node::Node::Directory)
-            } else {
-                self.i_symlinks.next().cloned().map(node::Node::Symlink)
-            }
-        } else {
-            // i_files is still in the game, compare with symlinks
-            if left_name_lt_right(self.i_files.peek(), self.i_symlinks.peek()) {
-                self.i_files.next().cloned().map(node::Node::File)
-            } else {
-                self.i_symlinks.next().cloned().map(node::Node::Symlink)
-            }
-        }
-    }
-}
diff --git a/tvix/castore/src/proto/tests/directory.rs b/tvix/castore/src/proto/tests/directory.rs
index 81b73a048d52..78b2cf7668e3 100644
--- a/tvix/castore/src/proto/tests/directory.rs
+++ b/tvix/castore/src/proto/tests/directory.rs
@@ -1,7 +1,5 @@
-use crate::proto::{
-    node, Directory, DirectoryNode, FileNode, SymlinkNode, ValidateDirectoryError,
-    ValidateNodeError,
-};
+use crate::proto::{Directory, DirectoryNode, FileNode, SymlinkNode, ValidateDirectoryError};
+use crate::ValidateNodeError;
 
 use hex_literal::hex;
 
@@ -149,7 +147,7 @@ fn digest() {
 #[test]
 fn validate_empty() {
     let d = Directory::default();
-    assert_eq!(d.validate(), Ok(()));
+    assert!(crate::directoryservice::Directory::try_from(d).is_ok());
 }
 
 #[test]
@@ -163,7 +161,7 @@ fn validate_invalid_names() {
             }],
             ..Default::default()
         };
-        match d.validate().expect_err("must fail") {
+        match crate::directoryservice::Directory::try_from(d).expect_err("must fail") {
             ValidateDirectoryError::InvalidNode(n, ValidateNodeError::InvalidName(_)) => {
                 assert_eq!(n, b"")
             }
@@ -180,7 +178,7 @@ fn validate_invalid_names() {
             }],
             ..Default::default()
         };
-        match d.validate().expect_err("must fail") {
+        match crate::directoryservice::Directory::try_from(d).expect_err("must fail") {
             ValidateDirectoryError::InvalidNode(n, ValidateNodeError::InvalidName(_)) => {
                 assert_eq!(n, b".")
             }
@@ -198,7 +196,7 @@ fn validate_invalid_names() {
             }],
             ..Default::default()
         };
-        match d.validate().expect_err("must fail") {
+        match crate::directoryservice::Directory::try_from(d).expect_err("must fail") {
             ValidateDirectoryError::InvalidNode(n, ValidateNodeError::InvalidName(_)) => {
                 assert_eq!(n, b"..")
             }
@@ -214,7 +212,7 @@ fn validate_invalid_names() {
             }],
             ..Default::default()
         };
-        match d.validate().expect_err("must fail") {
+        match crate::directoryservice::Directory::try_from(d).expect_err("must fail") {
             ValidateDirectoryError::InvalidNode(n, ValidateNodeError::InvalidName(_)) => {
                 assert_eq!(n, b"\x00")
             }
@@ -230,7 +228,7 @@ fn validate_invalid_names() {
             }],
             ..Default::default()
         };
-        match d.validate().expect_err("must fail") {
+        match crate::directoryservice::Directory::try_from(d).expect_err("must fail") {
             ValidateDirectoryError::InvalidNode(n, ValidateNodeError::InvalidName(_)) => {
                 assert_eq!(n, b"foo/bar")
             }
@@ -249,7 +247,7 @@ fn validate_invalid_digest() {
         }],
         ..Default::default()
     };
-    match d.validate().expect_err("must fail") {
+    match crate::directoryservice::Directory::try_from(d).expect_err("must fail") {
         ValidateDirectoryError::InvalidNode(_, ValidateNodeError::InvalidDigestLen(n)) => {
             assert_eq!(n, 2)
         }
@@ -276,7 +274,7 @@ fn validate_sorting() {
             ],
             ..Default::default()
         };
-        match d.validate().expect_err("must fail") {
+        match crate::directoryservice::Directory::try_from(d).expect_err("must fail") {
             ValidateDirectoryError::WrongSorting(s) => {
                 assert_eq!(s, b"a");
             }
@@ -301,7 +299,7 @@ fn validate_sorting() {
             ],
             ..Default::default()
         };
-        match d.validate().expect_err("must fail") {
+        match crate::directoryservice::Directory::try_from(d).expect_err("must fail") {
             ValidateDirectoryError::DuplicateName(s) => {
                 assert_eq!(s, b"a");
             }
@@ -327,7 +325,7 @@ fn validate_sorting() {
             ..Default::default()
         };
 
-        d.validate().expect("validate shouldn't error");
+        crate::directoryservice::Directory::try_from(d).expect("validate shouldn't error");
     }
 
     // [b, c] and [a] are both properly sorted.
@@ -352,101 +350,6 @@ fn validate_sorting() {
             ..Default::default()
         };
 
-        d.validate().expect("validate shouldn't error");
+        crate::directoryservice::Directory::try_from(d).expect("validate shouldn't error");
     }
 }
-
-#[test]
-fn validate_overflow() {
-    let d = Directory {
-        directories: vec![DirectoryNode {
-            name: "foo".into(),
-            digest: DUMMY_DIGEST.to_vec().into(),
-            size: u64::MAX,
-        }],
-        ..Default::default()
-    };
-
-    match d.validate().expect_err("must fail") {
-        ValidateDirectoryError::SizeOverflow => {}
-        _ => panic!("unexpected error"),
-    }
-}
-
-#[test]
-fn add_nodes_to_directory() {
-    let mut d = Directory {
-        ..Default::default()
-    };
-
-    d.add(node::Node::Directory(DirectoryNode {
-        name: "b".into(),
-        digest: DUMMY_DIGEST.to_vec().into(),
-        size: 1,
-    }));
-    d.add(node::Node::Directory(DirectoryNode {
-        name: "a".into(),
-        digest: DUMMY_DIGEST.to_vec().into(),
-        size: 1,
-    }));
-    d.add(node::Node::Directory(DirectoryNode {
-        name: "z".into(),
-        digest: DUMMY_DIGEST.to_vec().into(),
-        size: 1,
-    }));
-
-    d.add(node::Node::File(FileNode {
-        name: "f".into(),
-        digest: DUMMY_DIGEST.to_vec().into(),
-        size: 1,
-        executable: true,
-    }));
-    d.add(node::Node::File(FileNode {
-        name: "c".into(),
-        digest: DUMMY_DIGEST.to_vec().into(),
-        size: 1,
-        executable: true,
-    }));
-    d.add(node::Node::File(FileNode {
-        name: "g".into(),
-        digest: DUMMY_DIGEST.to_vec().into(),
-        size: 1,
-        executable: true,
-    }));
-
-    d.add(node::Node::Symlink(SymlinkNode {
-        name: "t".into(),
-        target: "a".into(),
-    }));
-    d.add(node::Node::Symlink(SymlinkNode {
-        name: "o".into(),
-        target: "a".into(),
-    }));
-    d.add(node::Node::Symlink(SymlinkNode {
-        name: "e".into(),
-        target: "a".into(),
-    }));
-
-    d.validate().expect("directory should be valid");
-}
-
-#[test]
-#[cfg_attr(not(debug_assertions), ignore)]
-#[should_panic = "name already exists in directories"]
-fn add_duplicate_node_to_directory_panics() {
-    let mut d = Directory {
-        ..Default::default()
-    };
-
-    d.add(node::Node::Directory(DirectoryNode {
-        name: "a".into(),
-        digest: DUMMY_DIGEST.to_vec().into(),
-        size: 1,
-    }));
-    d.add(node::Node::File(FileNode {
-        name: "a".into(),
-        digest: DUMMY_DIGEST.to_vec().into(),
-        size: 1,
-        executable: true,
-    }));
-}
diff --git a/tvix/castore/src/proto/tests/directory_nodes_iterator.rs b/tvix/castore/src/proto/tests/directory_nodes_iterator.rs
deleted file mode 100644
index 68f147a33210..000000000000
--- a/tvix/castore/src/proto/tests/directory_nodes_iterator.rs
+++ /dev/null
@@ -1,78 +0,0 @@
-use crate::proto::Directory;
-use crate::proto::DirectoryNode;
-use crate::proto::FileNode;
-use crate::proto::NamedNode;
-use crate::proto::SymlinkNode;
-
-#[test]
-fn iterator() {
-    let d = Directory {
-        directories: vec![
-            DirectoryNode {
-                name: "c".into(),
-                ..DirectoryNode::default()
-            },
-            DirectoryNode {
-                name: "d".into(),
-                ..DirectoryNode::default()
-            },
-            DirectoryNode {
-                name: "h".into(),
-                ..DirectoryNode::default()
-            },
-            DirectoryNode {
-                name: "l".into(),
-                ..DirectoryNode::default()
-            },
-        ],
-        files: vec![
-            FileNode {
-                name: "b".into(),
-                ..FileNode::default()
-            },
-            FileNode {
-                name: "e".into(),
-                ..FileNode::default()
-            },
-            FileNode {
-                name: "g".into(),
-                ..FileNode::default()
-            },
-            FileNode {
-                name: "j".into(),
-                ..FileNode::default()
-            },
-        ],
-        symlinks: vec![
-            SymlinkNode {
-                name: "a".into(),
-                ..SymlinkNode::default()
-            },
-            SymlinkNode {
-                name: "f".into(),
-                ..SymlinkNode::default()
-            },
-            SymlinkNode {
-                name: "i".into(),
-                ..SymlinkNode::default()
-            },
-            SymlinkNode {
-                name: "k".into(),
-                ..SymlinkNode::default()
-            },
-        ],
-    };
-
-    // We keep this strings here and convert to string to make the comparison
-    // less messy.
-    let mut node_names: Vec<String> = vec![];
-
-    for node in d.nodes() {
-        node_names.push(String::from_utf8(node.get_name().to_vec()).unwrap());
-    }
-
-    assert_eq!(
-        vec!["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l"],
-        node_names
-    );
-}
diff --git a/tvix/castore/src/proto/tests/mod.rs b/tvix/castore/src/proto/tests/mod.rs
index 8d903bacb6c5..74334029e84c 100644
--- a/tvix/castore/src/proto/tests/mod.rs
+++ b/tvix/castore/src/proto/tests/mod.rs
@@ -1,2 +1 @@
 mod directory;
-mod directory_nodes_iterator;