refactor(tvix/castore): add PathComponent type for checked components

This encodes a verified component on the type level. Internally, it
contains a bytes::Bytes.

The castore Path/PathBuf component() and file_name() methods now
return this type, the old ones returning bytes were renamed to
component_bytes() and component_file_name() respectively.

We can drop the directory_reject_invalid_name test - it's not possible
anymore to pass an invalid name to Directories::add.
Invalid names in the Directory proto are still being tested to be
rejected in the validate_invalid_names tests.

Change-Id: Ide4d16415dfd50b7e2d7e0c36d42a3bbeeb9b6c5
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12217
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: Connor Brewster <cbrewster@hey.com>
Tested-by: BuildkiteCI

tvix/store/src/import.rs

@@ -3,6 +3,7 @@ use std::path::Path;
 use tracing::{debug, instrument};
 use tvix_castore::{
     blobservice::BlobService, directoryservice::DirectoryService, import::fs::ingest_path, Node,
+    PathComponent,
 };
 
 use nix_compat::{
@@ -139,14 +140,19 @@ where
         )
     })?;
 
-    let name = bytes::Bytes::from(output_path.to_string());
+    let name: PathComponent = output_path
+        .to_string()
+        .as_str()
+        .try_into()
+        .expect("Tvix bug: StorePath must be PathComponent");
+
     log_node(name.as_ref(), &root_node, path.as_ref());
 
     let path_info = derive_nar_ca_path_info(
         nar_size,
         nar_sha256,
         Some(&CAHash::Nar(NixHash::Sha256(nar_sha256))),
-        output_path.to_string().into_bytes().into(),
+        name.into(),
         root_node,
     );
 

tvix/store/src/nar/renderer.rs

@@ -178,7 +178,7 @@ where
                     // and then recurse on that entry.
                     for (name, node) in directory.nodes() {
                         let child_node = nar_node_directory
-                            .entry(name)
+                            .entry(name.as_ref())
                             .await
                             .map_err(RenderError::NARWriterError)?;
 

tvix/store/src/pathinfoservice/fs/mod.rs

@@ -3,7 +3,7 @@ use futures::StreamExt;
 use tonic::async_trait;
 use tvix_castore::fs::{RootNodes, TvixStoreFs};
 use tvix_castore::{blobservice::BlobService, directoryservice::DirectoryService};
-use tvix_castore::{Error, Node};
+use tvix_castore::{Error, Node, PathComponent};
 
 use super::PathInfoService;
 
@@ -47,8 +47,8 @@ impl<T> RootNodes for RootNodesWrapper<T>
 where
     T: AsRef<dyn PathInfoService> + Send + Sync,
 {
-    async fn get_by_basename(&self, name: &[u8]) -> Result<Option<Node>, Error> {
-        let Ok(store_path) = nix_compat::store_path::StorePath::from_bytes(name) else {
+    async fn get_by_basename(&self, name: &PathComponent) -> Result<Option<Node>, Error> {
+        let Ok(store_path) = nix_compat::store_path::StorePath::from_bytes(name.as_ref()) else {
             return Ok(None);
         };
 
@@ -72,7 +72,7 @@ where
             .transpose()?)
     }
 
-    fn list(&self) -> BoxStream<Result<(bytes::Bytes, Node), Error>> {
+    fn list(&self) -> BoxStream<Result<(PathComponent, Node), Error>> {
         Box::pin(self.0.as_ref().list().map(|result| {
             result.and_then(|path_info| {
                 let node = path_info

tvix/store/src/proto/tests/pathinfo.rs

@@ -35,7 +35,7 @@ fn validate_pathinfo(
         name: DUMMY_PATH.into(),
         digest: Bytes::new(),
         size: 0,
-}, Err(ValidatePathInfoError::InvalidRootNode(DirectoryError::InvalidNode(DUMMY_PATH.into(), ValidateNodeError::InvalidDigestLen(0)))))]
+}, Err(ValidatePathInfoError::InvalidRootNode(DirectoryError::InvalidNode(DUMMY_PATH.try_into().unwrap(), ValidateNodeError::InvalidDigestLen(0)))))]
 #[case::invalid_node_name_no_storepath(castorepb::DirectoryNode {
         name: "invalid".into(),
         digest: DUMMY_DIGEST.clone().into(),
@@ -74,7 +74,7 @@ fn validate_directory(
         digest: Bytes::new(),
         ..Default::default()
     },
-    Err(ValidatePathInfoError::InvalidRootNode(DirectoryError::InvalidNode(DUMMY_PATH.into(), ValidateNodeError::InvalidDigestLen(0))))
+    Err(ValidatePathInfoError::InvalidRootNode(DirectoryError::InvalidNode(DUMMY_PATH.try_into().unwrap(), ValidateNodeError::InvalidDigestLen(0))))
 )]
 #[case::invalid_node_name(
     castorepb::FileNode {