feat(tvix/glue): Init fetcher builtins r/7557

Initialize a new empty builtins module `fetcher_builtins`, which will
contain the builtins which fetch URLs from the internet:

* fetchurl
* fetchGit
* fetchTarball
* fetchTree (maybe? this is experimental)

These builtins are all implemented in CPP nix at:
https://github.com/NixOS/nix/blob/2.20.2/src/libexpr/primops/fetchTree.cc

These builtins are added to the evaluation context using a similar
mechanism to the derivation builtins, and have been added everywhere
derivation builtins were previously being added.

Change-Id: I133b91cc9560f23028621414537f712e7bd8a825
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10974
Autosubmit: aspen <root@gws.fyi>
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

1 files changed, 42 insertions, 0 deletions

diff --git a/tvix/glue/src/builtins/fetchers.rs b/tvix/glue/src/builtins/fetchers.rs
new file mode 100644
index 0000000000..7a5d49a725
--- /dev/null
+++ b/tvix/glue/src/builtins/fetchers.rs
@@ -0,0 +1,42 @@
+//! Contains builtins that fetch paths from the Internet
+
+use crate::tvix_store_io::TvixStoreIO;
+use std::rc::Rc;
+use tvix_eval::builtin_macros::builtins;
+use tvix_eval::Value;
+
+#[allow(unused_variables)] // for the `state` arg, for now
+#[builtins(state = "Rc<TvixStoreIO>")]
+pub(crate) mod fetcher_builtins {
+    use super::*;
+
+    use tvix_eval::generators::Gen;
+    use tvix_eval::{generators::GenCo, ErrorKind};
+
+    #[builtin("fetchurl")]
+    async fn builtin_fetchurl(
+        state: Rc<TvixStoreIO>,
+        co: GenCo,
+        url: Value,
+    ) -> Result<Value, ErrorKind> {
+        Err(ErrorKind::NotImplemented("fetchurl"))
+    }
+
+    #[builtin("fetchTarball")]
+    async fn builtin_fetch_tarball(
+        state: Rc<TvixStoreIO>,
+        co: GenCo,
+        args: Value,
+    ) -> Result<Value, ErrorKind> {
+        Err(ErrorKind::NotImplemented("fetchTarball"))
+    }
+
+    #[builtin("fetchGit")]
+    async fn builtin_fetch_git(
+        state: Rc<TvixStoreIO>,
+        co: GenCo,
+        args: Value,
+    ) -> Result<Value, ErrorKind> {
+        Err(ErrorKind::NotImplemented("fetchGit"))
+    }
+}