chore(tvix/store): move protos into separate mod.rs

This allows adding more stuff into this namespace, from different files.

Also move tests on proto-related code from src/tests to src/proto/tests.

Change-Id: I49e066fce90efbc18e16d68f94497b32ed5625c0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8091
Reviewed-by: tazjin <tazjin@tvl.su>
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI

tvix/store/src/proto/mod.rs

@@ -0,0 +1,353 @@
+#![allow(clippy::derive_partial_eq_without_eq)]
+// https://github.com/hyperium/tonic/issues/1056
+use std::{collections::HashSet, iter::Peekable};
+use thiserror::Error;
+
+use prost::Message;
+
+use nix_compat::store_path::{ParseStorePathError, StorePath};
+
+tonic::include_proto!("tvix.store.v1");
+
+#[cfg(feature = "reflection")]
+/// Compiled file descriptors for implementing [gRPC
+/// reflection](https://github.com/grpc/grpc/blob/master/doc/server-reflection.md) with e.g.
+/// [`tonic_reflection`](https://docs.rs/tonic-reflection).
+pub const FILE_DESCRIPTOR_SET: &[u8] = tonic::include_file_descriptor_set!("tvix.store.v1");
+
+#[cfg(test)]
+mod tests;
+
+/// Errors that can occur during the validation of Directory messages.
+#[derive(Debug, PartialEq, Eq, Error)]
+pub enum ValidateDirectoryError {
+    /// Elements are not in sorted order
+    #[error("{0} is not sorted")]
+    WrongSorting(String),
+    /// Multiple elements with the same name encountered
+    #[error("{0} is a duplicate name")]
+    DuplicateName(String),
+    /// Invalid name encountered
+    #[error("Invalid name in {0}")]
+    InvalidName(String),
+    /// Invalid digest length encountered
+    #[error("Invalid Digest length: {0}")]
+    InvalidDigestLen(usize),
+}
+
+/// Errors that can occur during the validation of PathInfo messages.
+#[derive(Debug, Error, PartialEq)]
+pub enum ValidatePathInfoError {
+    /// No node present
+    #[error("No node present")]
+    NoNodePresent(),
+
+    /// Invalid node name encountered.
+    #[error("Failed to parse {0} as NixPath: {1}")]
+    InvalidNodeName(String, ParseStorePathError),
+
+    /// The digest the (root) node refers to has invalid length.
+    #[error("Invalid Digest length: {0}")]
+    InvalidDigestLen(usize),
+
+    /// The number of references in the narinfo.reference_names field does not match
+    /// the number of references in the .references field.
+    #[error("Inconsistent Number of References: {0} (references) vs {0} (narinfo)")]
+    InconsistentNumberOfReferences(usize, usize),
+}
+
+/// Checks a Node name for validity as an intermediate node, and returns an
+/// error that's generated from the supplied constructor.
+///
+/// We disallow slashes, null bytes, '.', '..' and the empty string.
+fn validate_node_name<E>(name: &str, err: fn(String) -> E) -> Result<(), E> {
+    if name.is_empty() || name == ".." || name == "." || name.contains('\x00') || name.contains('/')
+    {
+        return Err(err(name.to_string()));
+    }
+    Ok(())
+}
+
+/// Checks a digest for validity.
+/// Digests are 32 bytes long, as we store blake3 digests.
+fn validate_digest<E>(digest: &Vec<u8>, err: fn(usize) -> E) -> Result<(), E> {
+    if digest.len() != 32 {
+        return Err(err(digest.len()));
+    }
+    Ok(())
+}
+
+/// Parses a root node name.
+///
+/// On success, this returns the parsed [StorePath].
+/// On error, it returns an error generated from the supplied constructor.
+fn parse_node_name_root<E>(
+    name: &str,
+    err: fn(String, ParseStorePathError) -> E,
+) -> Result<StorePath, E> {
+    match StorePath::from_string(name) {
+        Ok(np) => Ok(np),
+        Err(e) => Err(err(name.to_string(), e)),
+    }
+}
+
+impl PathInfo {
+    /// validate performs some checks on the PathInfo struct,
+    /// Returning either a [StorePath] of the root node, or a
+    /// [ValidatePathInfoError].
+    pub fn validate(&self) -> Result<StorePath, ValidatePathInfoError> {
+        // If there is a narinfo field populated, ensure the number of references there
+        // matches PathInfo.references count.
+        if let Some(narinfo) = &self.narinfo {
+            if narinfo.reference_names.len() != self.references.len() {
+                return Err(ValidatePathInfoError::InconsistentNumberOfReferences(
+                    narinfo.reference_names.len(),
+                    self.references.len(),
+                ));
+            }
+        }
+        // FUTUREWORK: parse references in reference_names. ensure they start
+        // with storeDir, and use the same digest as in self.references.
+
+        // Ensure there is a (root) node present, and it properly parses to a [StorePath].
+        let root_nix_path = match &self.node {
+            None => {
+                return Err(ValidatePathInfoError::NoNodePresent());
+            }
+            Some(Node { node }) => match node {
+                None => {
+                    return Err(ValidatePathInfoError::NoNodePresent());
+                }
+                Some(node::Node::Directory(directory_node)) => {
+                    // ensure the digest has the appropriate size.
+                    validate_digest(
+                        &directory_node.digest,
+                        ValidatePathInfoError::InvalidDigestLen,
+                    )?;
+
+                    // parse the name
+                    parse_node_name_root(
+                        &directory_node.name,
+                        ValidatePathInfoError::InvalidNodeName,
+                    )?
+                }
+                Some(node::Node::File(file_node)) => {
+                    // ensure the digest has the appropriate size.
+                    validate_digest(&file_node.digest, ValidatePathInfoError::InvalidDigestLen)?;
+
+                    // parse the name
+                    parse_node_name_root(&file_node.name, ValidatePathInfoError::InvalidNodeName)?
+                }
+                Some(node::Node::Symlink(symlink_node)) => {
+                    // parse the name
+                    parse_node_name_root(
+                        &symlink_node.name,
+                        ValidatePathInfoError::InvalidNodeName,
+                    )?
+                }
+            },
+        };
+
+        // return the root nix path
+        Ok(root_nix_path)
+    }
+}
+
+/// 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) -> &str;
+}
+
+impl NamedNode for &FileNode {
+    fn get_name(&self) -> &str {
+        self.name.as_str()
+    }
+}
+
+impl NamedNode for &DirectoryNode {
+    fn get_name(&self) -> &str {
+        self.name.as_str()
+    }
+}
+
+impl NamedNode for &SymlinkNode {
+    fn get_name(&self) -> &str {
+        self.name.as_str()
+    }
+}
+
+impl NamedNode for node::Node {
+    fn get_name(&self) -> &str {
+        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,
+        }
+    }
+}
+
+/// 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<'set, 'n>(
+    prev_name: &'set mut &'n str,
+    name: &'n str,
+) -> Result<(), ValidateDirectoryError> {
+    if *name < **prev_name {
+        return Err(ValidateDirectoryError::WrongSorting(name.to_string()));
+    }
+    *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 str>,
+    name: &'n str,
+) -> Result<(), ValidateDirectoryError> {
+    if seen_names.get(name).is_some() {
+        return Err(ValidateDirectoryError::DuplicateName(name.to_string()));
+    }
+    seen_names.insert(name);
+    Ok(())
+}
+
+impl Directory {
+    /// The size of a directory is the number of all regular and symlink elements,
+    /// the number of directory elements, and their size fields.
+    pub fn size(&self) -> u32 {
+        self.files.len() as u32
+            + self.symlinks.len() as u32
+            + self
+                .directories
+                .iter()
+                .fold(0, |acc: u32, e| (acc + 1 + e.size))
+    }
+
+    /// Calculates the digest of a Directory, which is the blake3 hash of a
+    /// Directory protobuf message, serialized in protobuf canonical form.
+    pub fn digest(&self) -> Vec<u8> {
+        let mut hasher = blake3::Hasher::new();
+
+        hasher.update(&self.encode_to_vec()).finalize().as_bytes()[..].to_vec()
+    }
+
+    /// 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<&str> = HashSet::new();
+
+        let mut last_directory_name: &str = "";
+        let mut last_file_name: &str = "";
+        let mut last_symlink_name: &str = "";
+
+        // check directories
+        for directory_node in &self.directories {
+            validate_node_name(&directory_node.name, ValidateDirectoryError::InvalidName)?;
+            validate_digest(
+                &directory_node.digest,
+                ValidateDirectoryError::InvalidDigestLen,
+            )?;
+
+            update_if_lt_prev(&mut last_directory_name, directory_node.name.as_str())?;
+            insert_once(&mut seen_names, directory_node.name.as_str())?;
+        }
+
+        // check files
+        for file_node in &self.files {
+            validate_node_name(&file_node.name, ValidateDirectoryError::InvalidName)?;
+            validate_digest(&file_node.digest, ValidateDirectoryError::InvalidDigestLen)?;
+
+            update_if_lt_prev(&mut last_file_name, file_node.name.as_str())?;
+            insert_once(&mut seen_names, file_node.name.as_str())?;
+        }
+
+        // check symlinks
+        for symlink_node in &self.symlinks {
+            validate_node_name(&symlink_node.name, ValidateDirectoryError::InvalidName)?;
+
+            update_if_lt_prev(&mut last_symlink_name, symlink_node.name.as_str())?;
+            insert_once(&mut seen_names, symlink_node.name.as_str())?;
+        }
+
+        Ok(())
+    }
+
+    /// 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(),
+        };
+    }
+}
+
+/// 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)
+            }
+        }
+    }
+}