//! This module provides an implementation of EvalIO talking to tvix-store.
use async_recursion::async_recursion;
use bytes::Bytes;
use futures::{StreamExt, TryStreamExt};
use nix_compat::nixhash::NixHash;
use nix_compat::store_path::StorePathRef;
use nix_compat::{nixhash::CAHash, store_path::StorePath};
use sha2::{Digest, Sha256};
use std::{
cell::RefCell,
collections::BTreeSet,
io,
path::{Path, PathBuf},
sync::Arc,
};
use tokio_util::io::SyncIoBridge;
use tracing::{error, info, instrument, warn, Level};
use tvix_build::buildservice::BuildService;
use tvix_castore::proto::node::Node;
use tvix_eval::{EvalIO, FileType, StdIO};
use tvix_store::utils::AsyncIoBridge;
use tvix_castore::{
blobservice::BlobService,
directoryservice::{self, DirectoryService},
proto::NamedNode,
B3Digest,
};
use tvix_store::{pathinfoservice::PathInfoService, proto::PathInfo};
use crate::fetchers::Fetcher;
use crate::known_paths::KnownPaths;
use crate::tvix_build::derivation_to_build_request;
/// Implements [EvalIO], asking given [PathInfoService], [DirectoryService]
/// and [BlobService].
///
/// In case the given path does not exist in these stores, we ask StdIO.
/// This is to both cover cases of syntactically valid store paths, that exist
/// on the filesystem (still managed by Nix), as well as being able to read
/// files outside store paths.
///
/// This structure is also directly used by the derivation builtins
/// and tightly coupled to it.
///
/// In the future, we may revisit that coupling and figure out how to generalize this interface and
/// hide this implementation detail of the glue itself so that glue can be used with more than one
/// implementation of "Tvix Store IO" which does not necessarily bring the concept of blob service,
/// directory service or path info service.
pub struct TvixStoreIO {
// This is public so helper functions can interact with the stores directly.
pub(crate) blob_service: Arc<dyn BlobService>,
pub(crate) directory_service: Arc<dyn DirectoryService>,
pub(crate) path_info_service: Arc<dyn PathInfoService>,
std_io: StdIO,
#[allow(dead_code)]
build_service: Arc<dyn BuildService>,
pub(crate) tokio_handle: tokio::runtime::Handle,
pub(crate) fetcher:
Fetcher<Arc<dyn BlobService>, Arc<dyn DirectoryService>, Arc<dyn PathInfoService>>,
// Paths known how to produce, by building or fetching.
pub(crate) known_paths: RefCell<KnownPaths>,
}
impl TvixStoreIO {
pub fn new(
blob_service: Arc<dyn BlobService>,
directory_service: Arc<dyn DirectoryService>,
path_info_service: Arc<dyn PathInfoService>,
build_service: Arc<dyn BuildService>,
tokio_handle: tokio::runtime::Handle,
) -> Self {
Self {
blob_service: blob_service.clone(),
directory_service: directory_service.clone(),
path_info_service: path_info_service.clone(),
std_io: StdIO {},
build_service,
tokio_handle,
fetcher: Fetcher::new(blob_service, directory_service, path_info_service),
known_paths: Default::default(),
}
}
/// for a given [StorePath] and additional [Path] inside the store path,
/// look up the [PathInfo], and if it exists, and then use
/// [directoryservice::descend_to] to return the
/// [Node] specified by `sub_path`.
///
/// In case there is no PathInfo yet, this means we need to build it
/// (which currently is stubbed out still).
#[async_recursion(?Send)]
#[instrument(skip(self, store_path), fields(store_path=%store_path), ret(level = Level::TRACE), err)]
async fn store_path_to_node(
&self,
store_path: &StorePath,
sub_path: &Path,
) -> io::Result<Option<Node>> {
// Find the root node for the store_path.
// It asks the PathInfoService first, but in case there was a Derivation
// produced that would build it, fall back to triggering the build.
// To populate the input nodes, it might recursively trigger builds of
// its dependencies too.
let root_node = match self
.path_info_service
.as_ref()
.get(*store_path.digest())
.await?
{
// if we have a PathInfo, we know there will be a root_node (due to validation)
Some(path_info) => path_info.node.expect("no node").node.expect("no node"),
// If there's no PathInfo found, this normally means we have to
// trigger the build (and insert into PathInfoService, after
// reference scanning).
// However, as Tvix is (currently) not managing /nix/store itself,
// we return Ok(None) to let std_io take over.
// While reading from store paths that are not known to Tvix during
// that evaluation clearly is an impurity, we still need to support
// it for things like <nixpkgs> pointing to a store path.
// In the future, these things will (need to) have PathInfo.
None => {
// The store path doesn't exist yet, so we need to fetch or build it.
// We check for fetches first, as we might have both native
// fetchers and FODs in KnownPaths, and prefer the former.
let maybe_fetch = self
.known_paths
.borrow()
.get_fetch_for_output_path(store_path);
if let Some((name, fetch)) = maybe_fetch {
info!(?fetch, "triggering lazy fetch");
let (sp, root_node) = self
.fetcher
.ingest_and_persist(&name, fetch)
.await
.map_err(|e| std::io::Error::new(std::io::ErrorKind::InvalidData, e))?;
debug_assert_eq!(
sp.to_string(),
store_path.to_string(),
"store path returned from fetcher should match"
);
return Ok(Some(root_node));
}
// Look up the derivation for this output path.
let (drv_path, drv) = {
let known_paths = self.known_paths.borrow();
match known_paths.get_drv_path_for_output_path(store_path) {
Some(drv_path) => (
drv_path.to_owned(),
known_paths.get_drv_by_drvpath(drv_path).unwrap().to_owned(),
),
None => {
warn!(store_path=%store_path, "no drv found");
// let StdIO take over
return Ok(None);
}
}
};
warn!("triggering build");
// derivation_to_build_request needs castore nodes for all inputs.
// Provide them, which means, here is where we recursively build
// all dependencies.
#[allow(clippy::mutable_key_type)]
let input_nodes: BTreeSet<Node> =
futures::stream::iter(drv.input_derivations.iter())
.map(|(input_drv_path, output_names)| {
// look up the derivation object
let input_drv = {
let known_paths = self.known_paths.borrow();
known_paths
.get_drv_by_drvpath(input_drv_path)
.unwrap_or_else(|| panic!("{} not found", input_drv_path))
.to_owned()
};
// convert output names to actual paths
let output_paths: Vec<StorePath> = output_names
.iter()
.map(|output_name| {
input_drv
.outputs
.get(output_name)
.expect("missing output_name")
.path
.as_ref()
.expect("missing output path")
.clone()
})
.collect();
// For each output, ask for the castore node.
// We're in a per-derivation context, so if they're
// not built yet they'll all get built together.
// If they don't need to build, we can however still
// substitute all in parallel (if they don't need to
// be built) - so we turn this into a stream of streams.
// It's up to the builder to deduplicate same build requests.
futures::stream::iter(output_paths.into_iter()).map(
|output_path| async move {
let node = self
.store_path_to_node(&output_path, Path::new(""))
.await?;
if let Some(node) = node {
Ok(node)
} else {
Err(io::Error::other("no node produced"))
}
},
)
})
.flatten()
.buffer_unordered(10) // TODO: make configurable
.try_collect()
.await?;
// TODO: check if input sources are sufficiently dealth with,
// I think yes, they must be imported into the store by other
// operations, so dealt with in the Some(…) match arm
// synthesize the build request.
let build_request = derivation_to_build_request(&drv, input_nodes)?;
// create a build
let build_result = self
.build_service
.as_ref()
.do_build(build_request)
.await
.map_err(|e| std::io::Error::new(io::ErrorKind::Other, e))?;
// TODO: refscan?
// For each output, insert a PathInfo.
for output in &build_result.outputs {
let root_node = output.node.as_ref().expect("invalid root node");
// calculate the nar representation
let (nar_size, nar_sha256) =
self.path_info_service.calculate_nar(root_node).await?;
// assemble the PathInfo to persist
let path_info = PathInfo {
node: Some(tvix_castore::proto::Node {
node: Some(root_node.clone()),
}),
references: vec![], // TODO: refscan
narinfo: Some(tvix_store::proto::NarInfo {
nar_size,
nar_sha256: Bytes::from(nar_sha256.to_vec()),
signatures: vec![],
reference_names: vec![], // TODO: refscan
deriver: Some(tvix_store::proto::StorePath {
name: drv_path
.name()
.strip_suffix(".drv")
.expect("missing .drv suffix")
.to_string(),
digest: drv_path.digest().to_vec().into(),
}),
ca: drv.fod_digest().map(
|fod_digest| -> tvix_store::proto::nar_info::Ca {
(&CAHash::Nar(nix_compat::nixhash::NixHash::Sha256(fod_digest)))
.into()
},
),
}),
};
self.path_info_service
.put(path_info)
.await
.map_err(|e| std::io::Error::new(io::ErrorKind::Other, e))?;
}
// find the output for the store path requested
build_result
.outputs
.into_iter()
.find(|output_node| {
output_node.node.as_ref().expect("invalid node").get_name()
== store_path.to_string().as_bytes()
})
.expect("build didn't produce the store path")
.node
.expect("invalid node")
}
};
// now with the root_node and sub_path, descend to the node requested.
directoryservice::descend_to(&self.directory_service, root_node, sub_path)
.await
.map_err(|e| std::io::Error::new(io::ErrorKind::Other, e))
}
pub(crate) async fn node_to_path_info(
&self,
name: &str,
path: &Path,
ca: CAHash,
root_node: Node,
) -> io::Result<(PathInfo, NixHash, StorePath)> {
// Ask the PathInfoService for the NAR size and sha256
// We always need it no matter what is the actual hash mode
// because the path info construct a narinfo which *always*
// require a SHA256 of the NAR representation and the NAR size.
let (nar_size, nar_sha256) = self
.path_info_service
.as_ref()
.calculate_nar(&root_node)
.await?;
// Calculate the output path. This might still fail, as some names are illegal.
let output_path =
nix_compat::store_path::build_ca_path(name, &ca, Vec::<String>::new(), false).map_err(
|_| {
std::io::Error::new(
std::io::ErrorKind::InvalidData,
format!("invalid name: {}", name),
)
},
)?;
// assemble a new root_node with a name that is derived from the nar hash.
let root_node = root_node.rename(output_path.to_string().into_bytes().into());
tvix_store::import::log_node(&root_node, path);
let path_info =
tvix_store::import::derive_nar_ca_path_info(nar_size, nar_sha256, Some(ca), root_node);
Ok((
path_info,
NixHash::Sha256(nar_sha256),
output_path.to_owned(),
))
}
pub(crate) async fn register_node_in_path_info_service(
&self,
name: &str,
path: &Path,
ca: CAHash,
root_node: Node,
) -> io::Result<StorePath> {
let (path_info, _, output_path) = self.node_to_path_info(name, path, ca, root_node).await?;
let _path_info = self.path_info_service.as_ref().put(path_info).await?;
Ok(output_path)
}
/// Transforms a BLAKE-3 digest into a SHA256 digest
/// by re-hashing the whole file.
pub(crate) async fn blob_to_sha256_hash(&self, blob_digest: B3Digest) -> io::Result<[u8; 32]> {
let mut reader = self
.blob_service
.open_read(&blob_digest)
.await?
.ok_or_else(|| {
io::Error::new(
io::ErrorKind::NotFound,
format!("blob represented by digest: '{}' not found", blob_digest),
)
})?;
// It is fine to use `AsyncIoBridge` here because hashing is not actually I/O.
let mut hasher = AsyncIoBridge(Sha256::new());
tokio::io::copy(&mut reader, &mut hasher).await?;
Ok(hasher.0.finalize().into())
}
pub async fn store_path_exists<'a>(&'a self, store_path: StorePathRef<'a>) -> io::Result<bool> {
Ok(self
.path_info_service
.as_ref()
.get(*store_path.digest())
.await?
.is_some())
}
}
impl EvalIO for TvixStoreIO {
#[instrument(skip(self), ret(level = Level::TRACE), err)]
fn path_exists(&self, path: &Path) -> io::Result<bool> {
if let Ok((store_path, sub_path)) =
StorePath::from_absolute_path_full(&path.to_string_lossy())
{
if self
.tokio_handle
.block_on(async { self.store_path_to_node(&store_path, &sub_path).await })?
.is_some()
{
Ok(true)
} else {
// As tvix-store doesn't manage /nix/store on the filesystem,
// we still need to also ask self.std_io here.
self.std_io.path_exists(path)
}
} else {
// The store path is no store path, so do regular StdIO.
self.std_io.path_exists(path)
}
}
#[instrument(skip(self), err)]
fn open(&self, path: &Path) -> io::Result<Box<dyn io::Read>> {
if let Ok((store_path, sub_path)) =
StorePath::from_absolute_path_full(&path.to_string_lossy())
{
if let Some(node) = self
.tokio_handle
.block_on(async { self.store_path_to_node(&store_path, &sub_path).await })?
{
// depending on the node type, treat open differently
match node {
Node::Directory(_) => {
// This would normally be a io::ErrorKind::IsADirectory (still unstable)
Err(io::Error::new(
io::ErrorKind::Unsupported,
format!("tried to open directory at {:?}", path),
))
}
Node::File(file_node) => {
let digest: B3Digest =
file_node.digest.clone().try_into().map_err(|_e| {
error!(
file_node = ?file_node,
"invalid digest"
);
io::Error::new(
io::ErrorKind::InvalidData,
format!("invalid digest length in file node: {:?}", file_node),
)
})?;
self.tokio_handle.block_on(async {
let resp = self.blob_service.as_ref().open_read(&digest).await?;
match resp {
Some(blob_reader) => {
// The VM Response needs a sync [std::io::Reader].
Ok(Box::new(SyncIoBridge::new(blob_reader))
as Box<dyn io::Read>)
}
None => {
error!(
blob.digest = %digest,
"blob not found",
);
Err(io::Error::new(
io::ErrorKind::NotFound,
format!("blob {} not found", &digest),
))
}
}
})
}
Node::Symlink(_symlink_node) => Err(io::Error::new(
io::ErrorKind::Unsupported,
"open for symlinks is unsupported",
))?,
}
} else {
// As tvix-store doesn't manage /nix/store on the filesystem,
// we still need to also ask self.std_io here.
self.std_io.open(path)
}
} else {
// The store path is no store path, so do regular StdIO.
self.std_io.open(path)
}
}
#[instrument(skip(self), ret(level = Level::TRACE), err)]
fn read_dir(&self, path: &Path) -> io::Result<Vec<(bytes::Bytes, FileType)>> {
if let Ok((store_path, sub_path)) =
StorePath::from_absolute_path_full(&path.to_string_lossy())
{
if let Some(node) = self
.tokio_handle
.block_on(async { self.store_path_to_node(&store_path, &sub_path).await })?
{
match node {
Node::Directory(directory_node) => {
// fetch the Directory itself.
let digest: B3Digest =
directory_node.digest.clone().try_into().map_err(|_e| {
io::Error::new(
io::ErrorKind::InvalidData,
format!(
"invalid digest length in directory node: {:?}",
directory_node
),
)
})?;
if let Some(directory) = self.tokio_handle.block_on(async {
self.directory_service.as_ref().get(&digest).await
})? {
let mut children: Vec<(bytes::Bytes, FileType)> = Vec::new();
for node in directory.nodes() {
children.push(match node {
Node::Directory(e) => (e.name, FileType::Directory),
Node::File(e) => (e.name, FileType::Regular),
Node::Symlink(e) => (e.name, FileType::Symlink),
})
}
Ok(children)
} else {
// If we didn't get the directory node that's linked, that's a store inconsistency!
error!(
directory.digest = %digest,
path = ?path,
"directory not found",
);
Err(io::Error::new(
io::ErrorKind::NotFound,
format!("directory {digest} does not exist"),
))?
}
}
Node::File(_file_node) => {
// This would normally be a io::ErrorKind::NotADirectory (still unstable)
Err(io::Error::new(
io::ErrorKind::Unsupported,
"tried to readdir path {:?}, which is a file",
))?
}
Node::Symlink(_symlink_node) => Err(io::Error::new(
io::ErrorKind::Unsupported,
"read_dir for symlinks is unsupported",
))?,
}
} else {
self.std_io.read_dir(path)
}
} else {
self.std_io.read_dir(path)
}
}
#[instrument(skip(self), ret(level = Level::TRACE), err)]
fn import_path(&self, path: &Path) -> io::Result<PathBuf> {
let output_path = self.tokio_handle.block_on(async {
tvix_store::import::import_path_as_nar_ca(
path,
tvix_store::import::path_to_name(path)?,
&self.blob_service,
&self.directory_service,
&self.path_info_service,
)
.await
})?;
Ok(output_path.to_absolute_path().into())
}
#[instrument(skip(self), ret(level = Level::TRACE))]
fn store_dir(&self) -> Option<String> {
Some("/nix/store".to_string())
}
}
#[cfg(test)]
mod tests {
use std::{path::Path, rc::Rc, sync::Arc};
use bstr::ByteSlice;
use tempfile::TempDir;
use tvix_build::buildservice::DummyBuildService;
use tvix_castore::{
blobservice::{BlobService, MemoryBlobService},
directoryservice::{DirectoryService, MemoryDirectoryService},
};
use tvix_eval::{EvalIO, EvaluationResult};
use tvix_store::pathinfoservice::MemoryPathInfoService;
use super::TvixStoreIO;
use crate::builtins::{add_derivation_builtins, add_fetcher_builtins, add_import_builtins};
/// evaluates a given nix expression and returns the result.
/// Takes care of setting up the evaluator so it knows about the
// `derivation` builtin.
fn eval(str: &str) -> EvaluationResult {
let blob_service = Arc::new(MemoryBlobService::default()) as Arc<dyn BlobService>;
let directory_service =
Arc::new(MemoryDirectoryService::default()) as Arc<dyn DirectoryService>;
let path_info_service = Arc::new(MemoryPathInfoService::new(
blob_service.clone(),
directory_service.clone(),
));
let runtime = tokio::runtime::Runtime::new().unwrap();
let io = Rc::new(TvixStoreIO::new(
blob_service.clone(),
directory_service.clone(),
path_info_service,
Arc::<DummyBuildService>::default(),
runtime.handle().clone(),
));
let mut eval = tvix_eval::Evaluation::new(io.clone() as Rc<dyn EvalIO>, true);
add_derivation_builtins(&mut eval, io.clone());
add_fetcher_builtins(&mut eval, io.clone());
add_import_builtins(&mut eval, io);
// run the evaluation itself.
eval.evaluate(str, None)
}
/// Helper function that takes a &Path, and invokes a tvix evaluator coercing that path to a string
/// (via "${/this/path}"). The path can be both absolute or not.
/// It returns Option<String>, depending on whether the evaluation succeeded or not.
fn import_path_and_compare<P: AsRef<Path>>(p: P) -> Option<String> {
// Try to import the path using "${/tmp/path/to/test}".
// The format string looks funny, the {} passed to Nix needs to be
// escaped.
let code = format!(r#""${{{}}}""#, p.as_ref().display());
let result = eval(&code);
if !result.errors.is_empty() {
return None;
}
let value = result.value.expect("must be some");
match value {
tvix_eval::Value::String(s) => Some(s.to_str_lossy().into_owned()),
_ => panic!("unexpected value type: {:?}", value),
}
}
/// Import a directory with a zero-sized ".keep" regular file.
/// Ensure it matches the (pre-recorded) store path that Nix would produce.
#[test]
fn import_directory() {
let tmpdir = TempDir::new().unwrap();
// create a directory named "test"
let src_path = tmpdir.path().join("test");
std::fs::create_dir(&src_path).unwrap();
// write a regular file `.keep`.
std::fs::write(src_path.join(".keep"), vec![]).unwrap();
// importing the path with .../test at the end.
assert_eq!(
Some("/nix/store/gq3xcv4xrj4yr64dflyr38acbibv3rm9-test".to_string()),
import_path_and_compare(&src_path)
);
// importing the path with .../test/. at the end.
assert_eq!(
Some("/nix/store/gq3xcv4xrj4yr64dflyr38acbibv3rm9-test".to_string()),
import_path_and_compare(src_path.join("."))
);
}
/// Import a file into the store. Nix uses the "recursive"/NAR-based hashing
/// scheme for these.
#[test]
fn import_file() {
let tmpdir = TempDir::new().unwrap();
// write a regular file `empty`.
std::fs::write(tmpdir.path().join("empty"), vec![]).unwrap();
assert_eq!(
Some("/nix/store/lx5i78a4izwk2qj1nq8rdc07y8zrwy90-empty".to_string()),
import_path_and_compare(tmpdir.path().join("empty"))
);
// write a regular file `hello.txt`.
std::fs::write(tmpdir.path().join("hello.txt"), b"Hello World!").unwrap();
assert_eq!(
Some("/nix/store/925f1jb1ajrypjbyq7rylwryqwizvhp0-hello.txt".to_string()),
import_path_and_compare(tmpdir.path().join("hello.txt"))
);
}
/// Invoke toString on a nonexisting file, and access the .file attribute.
/// This should not cause an error, because it shouldn't trigger an import,
/// and leave the path as-is.
#[test]
fn nonexisting_path_without_import() {
let result = eval("toString ({ line = 42; col = 42; file = /deep/thought; }.file)");
assert!(result.errors.is_empty(), "expect evaluation to succeed");
let value = result.value.expect("must be some");
match value {
tvix_eval::Value::String(s) => {
assert_eq!(*s, "/deep/thought");
}
_ => panic!("unexpected value type: {:?}", value),
}
}
}
