feat(tvix/glue): support builtin:fetchurl r/8254

nixpkgs calls <nix/fetchurl.nix> during nixpkgs bootstrap.

This produces a fake derivation with system = builtin
and builder = builtin:fetchurl, and needs to download files from the
internet.

At the end of the Derivation construction, if we have such a derivation,
also synthesize a `Fetch` struct, which we add to the known fetch paths.

This will then cause these fetches to be picked up like all other
fetches in TvixStoreIO.

Change-Id: I72cbca4f85da106b25eda97693a6a6e59911cd57
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10975
Reviewed-by: Connor Brewster <cbrewster@hey.com>
Tested-by: BuildkiteCI

1 files changed, 5 insertions, 5 deletions

diff --git a/tvix/glue/src/tvix_store_io.rs b/tvix/glue/src/tvix_store_io.rs
index f32dea512ee3..697b5a1dde8a 100644
--- a/tvix/glue/src/tvix_store_io.rs
+++ b/tvix/glue/src/tvix_store_io.rs
@@ -1,5 +1,4 @@
 //! This module provides an implementation of EvalIO talking to tvix-store.
-
 use bytes::Bytes;
 use futures::{StreamExt, TryStreamExt};
 use nix_compat::nixhash::NixHash;
@@ -138,7 +137,8 @@ impl TvixStoreIO {
                 // 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.
-
+                // This will also find [Fetch] synthesized from
+                // `builtin:fetchurl` Derivations.
                 let maybe_fetch = self
                     .known_paths
                     .borrow()
@@ -156,9 +156,9 @@ impl TvixStoreIO {
                         })?;
 
                         debug_assert_eq!(
-                            sp.to_string(),
-                            store_path.to_string(),
-                            "store path returned from fetcher should match"
+                            sp.to_absolute_path(),
+                            store_path.as_ref().to_absolute_path(),
+                            "store path returned from fetcher must match store path we have in fetchers"
                         );
 
                         root_node