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

4 files changed, 64 insertions, 5 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"))
+    }
+}
diff --git a/tvix/glue/src/builtins/mod.rs b/tvix/glue/src/builtins/mod.rs
index dff6a8947c..4a59ec9ea6 100644
--- a/tvix/glue/src/builtins/mod.rs
+++ b/tvix/glue/src/builtins/mod.rs
@@ -6,6 +6,7 @@ use crate::tvix_store_io::TvixStoreIO;
 
 mod derivation;
 mod derivation_error;
+mod fetchers;
 
 pub use derivation_error::Error as DerivationError;
 
@@ -17,20 +18,30 @@ pub use derivation_error::Error as DerivationError;
 /// `known_paths`.
 pub fn add_derivation_builtins<IO>(eval: &mut tvix_eval::Evaluation<IO>, io: Rc<TvixStoreIO>) {
     eval.builtins
-        .extend(derivation::derivation_builtins::builtins(io));
+        .extend(derivation::derivation_builtins::builtins(Rc::clone(&io)));
 
     // Add the actual `builtins.derivation` from compiled Nix code
     eval.src_builtins
         .push(("derivation", include_str!("derivation.nix")));
 }
 
+/// Adds fetcher builtins to the passed [tvix_eval::Evaluation]:
+///
+/// * `fetchurl`
+/// * `fetchTarball`
+/// * `fetchGit`
+pub fn add_fetcher_builtins<IO>(eval: &mut tvix_eval::Evaluation<IO>, io: Rc<TvixStoreIO>) {
+    eval.builtins
+        .extend(fetchers::fetcher_builtins::builtins(Rc::clone(&io)));
+}
+
 #[cfg(test)]
 mod tests {
     use std::{rc::Rc, sync::Arc};
 
     use crate::tvix_store_io::TvixStoreIO;
 
-    use super::add_derivation_builtins;
+    use super::{add_derivation_builtins, add_fetcher_builtins};
     use nix_compat::store_path::hash_placeholder;
     use test_case::test_case;
     use tvix_build::buildservice::DummyBuildService;
@@ -57,7 +68,8 @@ mod tests {
 
         let mut eval = tvix_eval::Evaluation::new(io.clone() as Rc<dyn EvalIO>, false);
 
-        add_derivation_builtins(&mut eval, io);
+        add_derivation_builtins(&mut eval, Rc::clone(&io));
+        add_fetcher_builtins(&mut eval, io);
 
         // run the evaluation itself.
         eval.evaluate(str, None)
diff --git a/tvix/glue/src/tests/mod.rs b/tvix/glue/src/tests/mod.rs
index ddc1391580..ad6571e4d2 100644
--- a/tvix/glue/src/tests/mod.rs
+++ b/tvix/glue/src/tests/mod.rs
@@ -12,7 +12,10 @@ use tvix_store::pathinfoservice::{MemoryPathInfoService, PathInfoService};
 
 use rstest::rstest;
 
-use crate::{builtins::add_derivation_builtins, tvix_store_io::TvixStoreIO};
+use crate::{
+    builtins::{add_derivation_builtins, add_fetcher_builtins},
+    tvix_store_io::TvixStoreIO,
+};
 
 fn eval_test(code_path: PathBuf, expect_success: bool) {
     assert_eq!(
@@ -51,6 +54,7 @@ fn eval_test(code_path: PathBuf, expect_success: bool) {
 
     eval.strict = true;
     add_derivation_builtins(&mut eval, tvix_store_io.clone());
+    add_fetcher_builtins(&mut eval, tvix_store_io);
 
     let result = eval.evaluate(code, Some(code_path.clone()));
     let failed = match result.value {
diff --git a/tvix/glue/src/tvix_store_io.rs b/tvix/glue/src/tvix_store_io.rs
index a64e2d4c7b..025a8a4bf0 100644
--- a/tvix/glue/src/tvix_store_io.rs
+++ b/tvix/glue/src/tvix_store_io.rs
@@ -475,7 +475,7 @@ mod tests {
     use tvix_eval::{EvalIO, EvaluationResult};
     use tvix_store::pathinfoservice::MemoryPathInfoService;
 
-    use crate::builtins::add_derivation_builtins;
+    use crate::builtins::{add_derivation_builtins, add_fetcher_builtins};
 
     use super::TvixStoreIO;
 
@@ -503,6 +503,7 @@ mod tests {
         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());
 
         // run the evaluation itself.
         eval.evaluate(str, None)