feat(tvix/eval): Implement builtins.fetchTarball

Implement a first pass at the fetchTarball builtin.

This uses much of the same machinery as fetchUrl, but has the extra
complexity that tarballs have to be extracted and imported as store
paths (into the directory- and blob-services) before hashing. That's
reasonably involved due to the structure of those two services.

This is (unfortunately) not easy to test in an automated way, but I've
tested it manually for now and it seems to work:

    tvix-repl> (import ../. {}).third_party.nixpkgs.hello.outPath
    => "/nix/store/dbghhbq1x39yxgkv3vkgfwbxrmw9nfzi-hello-2.12.1" :: string

Co-authored-by: Connor Brewster <cbrewster@hey.com>
Change-Id: I57afc6b91bad617a608a35bb357861e782a864c8
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11020
Autosubmit: aspen <root@gws.fyi>
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

tvix/glue/src/builtins/fetchers.rs

@@ -175,12 +175,21 @@ async fn fetch(
         }
     }
 
-    let hash = args.hash.as_ref().map(|h| h.hash());
-    let store_path = Rc::clone(&state).tokio_handle.block_on(state.fetch_url(
-        &args.url,
-        &args.name,
-        hash.as_deref(),
-    ))?;
+    let ca = args.hash;
+    let store_path = Rc::clone(&state).tokio_handle.block_on(async move {
+        match mode {
+            FetchMode::Url => {
+                state
+                    .fetch_url(
+                        &args.url,
+                        &args.name,
+                        ca.as_ref().map(|c| c.hash().into_owned()).as_ref(),
+                    )
+                    .await
+            }
+            FetchMode::Tarball => state.fetch_tarball(&args.url, &args.name, ca).await,
+        }
+    })?;
 
     Ok(string_from_store_path(store_path.as_ref()).into())
 }

tvix/glue/src/builtins/import.rs

@@ -205,7 +205,7 @@ mod import_builtins {
         };
 
         let obtained_hash = ca.hash().clone().into_owned();
-        let (path_info, output_path) = state.tokio_handle.block_on(async {
+        let (path_info, _hash, output_path) = state.tokio_handle.block_on(async {
             state
                 .node_to_path_info(name.as_ref(), path.as_ref(), ca, root_node)
                 .await

tvix/glue/src/tvix_store_io.rs

@@ -15,9 +15,11 @@ use std::{
     path::{Path, PathBuf},
     sync::Arc,
 };
-use tokio_util::io::SyncIoBridge;
+use tokio::io::AsyncBufRead;
+use tokio_util::io::{InspectReader, SyncIoBridge};
 use tracing::{error, instrument, warn, Level};
 use tvix_build::buildservice::BuildService;
+use tvix_castore::import::archive::ingest_archive;
 use tvix_castore::import::fs::dir_entry_iter_to_ingestion_stream;
 use tvix_eval::{ErrorKind, EvalIO, FileType, StdIO};
 use tvix_store::utils::AsyncIoBridge;
@@ -32,6 +34,7 @@ use tvix_castore::{
 use tvix_store::{pathinfoservice::PathInfoService, proto::PathInfo};
 
 use crate::builtins::FetcherError;
+use crate::decompression::DecompressedReader;
 use crate::known_paths::KnownPaths;
 use crate::tvix_build::derivation_to_build_request;
 
@@ -298,7 +301,7 @@ impl TvixStoreIO {
         path: &Path,
         ca: CAHash,
         root_node: Node,
-    ) -> io::Result<(PathInfo, StorePath)> {
+    ) -> 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*
@@ -327,7 +330,11 @@ impl TvixStoreIO {
         let path_info =
             tvix_store::import::derive_nar_ca_path_info(nar_size, nar_sha256, Some(ca), root_node);
 
-        Ok((path_info, output_path.to_owned()))
+        Ok((
+            path_info,
+            NixHash::Sha256(nar_sha256),
+            output_path.to_owned(),
+        ))
     }
 
     pub(crate) async fn register_node_in_path_info_service(
@@ -337,7 +344,7 @@ impl TvixStoreIO {
         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, _, 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)
@@ -372,33 +379,34 @@ impl TvixStoreIO {
             .is_some())
     }
 
-    pub async fn fetch_url(
-        &self,
-        url: &str,
-        name: &str,
-        hash: Option<&NixHash>,
-    ) -> Result<StorePath, ErrorKind> {
+    async fn download<'a>(&self, url: &str) -> Result<impl AsyncBufRead + Unpin + 'a, ErrorKind> {
         let resp = self
             .http_client
             .get(url)
             .send()
             .await
             .map_err(FetcherError::from)?;
-        let mut sha = Sha256::new();
-        let mut data = tokio_util::io::StreamReader::new(
-            resp.bytes_stream()
-                .inspect_ok(|data| {
-                    sha.update(data);
-                })
-                .map_err(|e| {
-                    let e = e.without_url();
-                    warn!(%e, "failed to get response body");
-                    io::Error::new(io::ErrorKind::BrokenPipe, e.to_string())
-                }),
-        );
+        Ok(tokio_util::io::StreamReader::new(
+            resp.bytes_stream().map_err(|e| {
+                let e = e.without_url();
+                warn!(%e, "failed to get response body");
+                io::Error::new(io::ErrorKind::BrokenPipe, e.to_string())
+            }),
+        ))
+    }
 
+    pub async fn fetch_url(
+        &self,
+        url: &str,
+        name: &str,
+        hash: Option<&NixHash>,
+    ) -> Result<StorePath, ErrorKind> {
+        let mut sha = Sha256::new();
+        let data = self.download(url).await?;
+        let mut data = InspectReader::new(data, |b| sha.update(b));
         let mut blob = self.blob_service.open_write().await;
         let size = tokio::io::copy(&mut data, blob.as_mut()).await?;
+        drop(data);
         let blob_digest = blob.close().await?;
         let got = NixHash::Sha256(sha.finalize().into());
 
@@ -453,6 +461,47 @@ impl TvixStoreIO {
 
         Ok(path.to_owned())
     }
+
+    pub async fn fetch_tarball(
+        &self,
+        url: &str,
+        name: &str,
+        ca: Option<CAHash>,
+    ) -> Result<StorePath, ErrorKind> {
+        let data = self.download(url).await?;
+        let data = DecompressedReader::new(data);
+        let archive = tokio_tar::Archive::new(data);
+        let node = ingest_archive(&self.blob_service, &self.directory_service, archive)
+            .await
+            .map_err(|e| std::io::Error::new(io::ErrorKind::Other, e))?;
+
+        let (path_info, got, output_path) = self
+            .node_to_path_info(
+                name,
+                Path::new(""),
+                ca.clone().expect("TODO: support unspecified CA hash"),
+                node,
+            )
+            .await?;
+
+        if let Some(wanted) = &ca {
+            if *wanted.hash() != got {
+                return Err(FetcherError::HashMismatch {
+                    url: url.to_owned(),
+                    wanted: wanted.hash().into_owned(),
+                    got,
+                }
+                .into());
+            }
+        }
+
+        self.path_info_service
+            .put(path_info)
+            .await
+            .map_err(|e| std::io::Error::new(io::ErrorKind::Other, e))?;
+
+        Ok(output_path)
+    }
 }
 
 impl EvalIO for TvixStoreIO {