feat(tvix/derivation): implement output path calculation r/5610

This implement output path calculation for fixed outputs, both fixed-
output and non-fixed-output.

Change-Id: I0a77b99f2ba6b39467cc5dd589ce152a40387f9a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7761
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Reviewed-by: jrhahn <mail.jhahn@gmail.com>

1 files changed, 93 insertions, 0 deletions

diff --git a/tvix/derivation/src/tests/mod.rs b/tvix/derivation/src/tests/mod.rs
index 623cc4e5b13a..dbba6e521511 100644
--- a/tvix/derivation/src/tests/mod.rs
+++ b/tvix/derivation/src/tests/mod.rs
@@ -1,4 +1,5 @@
 use crate::derivation::Derivation;
+use crate::output::Output;
 use std::fs::File;
 use std::io::Read;
 use std::path::Path;
@@ -67,3 +68,95 @@ fn derivation_path(name: &str, expected_path: &str) {
         NixPath::from_string(expected_path).unwrap()
     );
 }
+
+/// This trims all outputs from a Derivation struct,
+/// by setting outputs[$outputName].path and environment[$outputName] to the empty string.
+fn derivation_with_trimmed_outputs(derivation: &Derivation) -> Derivation {
+    let mut trimmed_env = derivation.environment.clone();
+    let mut trimmed_outputs = derivation.outputs.clone();
+
+    for (output_name, output) in &derivation.outputs {
+        trimmed_env.insert(output_name.clone(), "".to_string());
+        assert!(trimmed_outputs.contains_key(output_name));
+        trimmed_outputs.insert(
+            output_name.to_string(),
+            Output {
+                path: "".to_string(),
+                ..output.clone()
+            },
+        );
+    }
+
+    // replace environment and outputs with the trimmed variants
+    Derivation {
+        environment: trimmed_env,
+        outputs: trimmed_outputs,
+        ..derivation.clone()
+    }
+}
+
+#[test_case("0hm2f1psjpcwg8fijsmr4wwxrx59s092-bar.drv", "724f3e3634fce4cbbbd3483287b8798588e80280660b9a63fd13a1bc90485b33"; "fixed_sha256")]
+#[test_case("ss2p4wmxijn652haqyd7dckxwl4c7hxx-bar.drv", "c79aebd0ce3269393d4a1fde2cbd1d975d879b40f0bf40a48f550edc107fd5df";"fixed-sha1")]
+fn replacement_drv_path(drv_path: &str, expected_replacement_str: &str) {
+    // read in the fixture
+    let data = read_file(&format!("{}/{}.json", RESOURCES_PATHS, drv_path));
+    let drv: Derivation = serde_json::from_str(&data).expect("must deserialize");
+
+    let drv_replacement_str = drv.calculate_drv_replacement_str(|_| panic!("must not be called"));
+
+    assert_eq!(expected_replacement_str, drv_replacement_str);
+}
+
+#[test_case("bar","0hm2f1psjpcwg8fijsmr4wwxrx59s092-bar.drv"; "fixed_sha256")]
+#[test_case("foo", "4wvvbi4jwn0prsdxb7vs673qa5h9gr7x-foo.drv"; "simple-sha256")]
+#[test_case("bar", "ss2p4wmxijn652haqyd7dckxwl4c7hxx-bar.drv"; "fixed-sha1")]
+#[test_case("foo", "ch49594n9avinrf8ip0aslidkc4lxkqv-foo.drv"; "simple-sha1")]
+#[test_case("has-multi-out", "h32dahq0bx5rp1krcdx3a53asj21jvhk-has-multi-out.drv"; "multiple-outputs")]
+#[test_case("structured-attrs", "9lj1lkjm2ag622mh4h9rpy6j607an8g2-structured-attrs.drv"; "structured-attrs")]
+#[test_case("unicode", "52a9id8hx688hvlnz4d1n25ml1jdykz0-unicode.drv"; "unicode")]
+fn output_paths(name: &str, drv_path: &str) {
+    // read in the fixture
+    let data = read_file(&format!("{}/{}.json", RESOURCES_PATHS, drv_path));
+    let expected_derivation: Derivation = serde_json::from_str(&data).expect("must deserialize");
+
+    let mut derivation = derivation_with_trimmed_outputs(&expected_derivation);
+
+    // calculate the drv replacement string.
+    // We don't expect the lookup function to be called for most derivations.
+    let replacement_str = derivation.calculate_drv_replacement_str(|drv_name| {
+        // 4wvvbi4jwn0prsdxb7vs673qa5h9gr7x-foo.drv may lookup /nix/store/0hm2f1psjpcwg8fijsmr4wwxrx59s092-bar.drv
+        // ch49594n9avinrf8ip0aslidkc4lxkqv-foo.drv may lookup /nix/store/ss2p4wmxijn652haqyd7dckxwl4c7hxx-bar.drv
+        if name == "foo"
+            && ((drv_path == "4wvvbi4jwn0prsdxb7vs673qa5h9gr7x-foo.drv"
+                && drv_name == "/nix/store/0hm2f1psjpcwg8fijsmr4wwxrx59s092-bar.drv")
+                || (drv_path == "ch49594n9avinrf8ip0aslidkc4lxkqv-foo.drv"
+                    && drv_name == "/nix/store/ss2p4wmxijn652haqyd7dckxwl4c7hxx-bar.drv"))
+        {
+            // do the lookup, by reading in the fixture of the requested
+            // drv_name, and calculating its drv replacement (on the non-stripped version)
+            // In a real-world scenario you would have already done this during construction.
+
+            let data = read_file(&format!(
+                "{}/{}.json",
+                RESOURCES_PATHS,
+                Path::new(drv_name).file_name().unwrap().to_string_lossy()
+            ));
+
+            let drv: Derivation = serde_json::from_str(&data).expect("must deserialize");
+
+            // calculate replacement string. These don't trigger any subsequent requests, as they're both FOD.
+            drv.calculate_drv_replacement_str(|_| panic!("must not lookup"))
+        } else {
+            // we only expect this to be called in the "foo" testcase, for the "bar derivations"
+            panic!("may only be called for foo testcase on bar derivations");
+        }
+    });
+
+    // We need to calculate the replacement_str, as fixed-sha1 does use it.
+    derivation
+        .calculate_output_paths(&name, &replacement_str)
+        .unwrap();
+
+    // The derivation should now look like it was before
+    assert_eq!(expected_derivation, derivation);
+}