feat: write llar artifact metadata

cmd/llar/internal/make.go

@@ -3,6 +3,7 @@ package internal
 import (
 	"archive/zip"
 	"context"
+	"encoding/json"
 	"fmt"
 	stdbuild "go/build"
 	"io"
@@ -24,6 +25,11 @@ import (
 var makeVerbose bool
 var makeOutput string
 
+type artifactMetadata struct {
+	Metadata string   `json:"metadata"`
+	Deps     []string `json:"deps,omitempty"`
+}
+
 // newRemoteStore creates the remote formula store. Overridable for testing.
 var newRemoteStore = func() (repo.Store, error) {
 	formulaDir, err := repo.DefaultDir()
@@ -186,7 +192,7 @@ func buildModule(ctx context.Context, store repo.Store, modPath, version, matrix
 			fmt.Println(main.Metadata)
 		}
 		if makeOutput != "" {
-			if err := outputResult(main.OutputDir, makeOutput); err != nil {
+			if err := outputArtifact(main.OutputDir, makeOutput, main.Metadata, artifactDeps(mods)); err != nil {
 				return fmt.Errorf("failed to write output: %w", err)
 			}
 		}
@@ -257,6 +263,55 @@ func parseModuleArg(arg string) (pattern, version string, isLocal bool, err erro
 	return
 }
 
+func writeArtifactMetadata(installDir, metadata string, deps []module.Version) error {
+	body, err := json.MarshalIndent(artifactMetadata{
+		Metadata: metadata,
+		Deps:     artifactDepStrings(deps),
+	}, "", "  ")
+	if err != nil {
+		return err
+	}
+
+	metaDir := filepath.Join(installDir, ".llar")
+	if err := os.MkdirAll(metaDir, 0o755); err != nil {
+		return err
+	}
+	return os.WriteFile(filepath.Join(metaDir, "metadata.json"), append(body, '\n'), 0o644)
+}
+
+func artifactDeps(mods []*modules.Module) []module.Version {
+	if len(mods) <= 1 {
+		return nil
+	}
+	deps := make([]module.Version, 0, len(mods)-1)
+	main := mods[0]
+	for _, mod := range mods[1:] {
+		if mod.Path == main.Path && mod.Version == main.Version {
+			continue
+		}
+		deps = append(deps, module.Version{Path: mod.Path, Version: mod.Version})
+	}
+	return deps
+}
+
+func artifactDepStrings(deps []module.Version) []string {
+	if len(deps) == 0 {
+		return nil
+	}
+	out := make([]string, 0, len(deps))
+	for _, dep := range deps {
+		out = append(out, dep.Path+"@"+dep.Version)
+	}
+	return out
+}
+
+func outputArtifact(srcDir, dest, metadata string, deps []module.Version) error {
+	if err := writeArtifactMetadata(srcDir, metadata, deps); err != nil {
+		return err
+	}
+	return outputResult(srcDir, dest)
+}
+
 // outputResult writes the build output to dest.
 // If dest ends with ".zip", creates a zip archive; otherwise copies the directory.
 func outputResult(srcDir, dest string) error {

cmd/llar/internal/make_test.go

@@ -11,6 +11,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"reflect"
 	"runtime"
 	"strings"
 	"testing"
@@ -129,6 +130,117 @@ func setupTestSrcDir(t *testing.T) string {
 	return src
 }
 
+func TestWriteArtifactMetadataWritesMetadataAndDeps(t *testing.T) {
+	installDir := t.TempDir()
+	metadata := fmt.Sprintf("-I%s -L%s -lz", filepath.Join(installDir, "include"), filepath.Join(installDir, "lib"))
+	deps := []module.Version{{Path: "madler/zlib", Version: "v1.3.1"}}
+
+	if err := writeArtifactMetadata(installDir, metadata, deps); err != nil {
+		t.Fatalf("writeArtifactMetadata: %v", err)
+	}
+
+	data, err := os.ReadFile(filepath.Join(installDir, ".llar", "metadata.json"))
+	if err != nil {
+		t.Fatalf("read metadata.json: %v", err)
+	}
+	var got struct {
+		Metadata string   `json:"metadata"`
+		Deps     []string `json:"deps"`
+	}
+	if err := json.Unmarshal(data, &got); err != nil {
+		t.Fatalf("metadata.json is invalid JSON: %v", err)
+	}
+	if got.Metadata != metadata {
+		t.Fatalf("metadata = %q, want %q", got.Metadata, metadata)
+	}
+	wantDeps := []string{"madler/zlib@v1.3.1"}
+	if !reflect.DeepEqual(got.Deps, wantDeps) {
+		t.Fatalf("deps = %+v, want %+v", got.Deps, wantDeps)
+	}
+}
+
+func TestWriteArtifactMetadataOmitsEmptyDeps(t *testing.T) {
+	installDir := t.TempDir()
+	if err := writeArtifactMetadata(installDir, "-lstandalone", nil); err != nil {
+		t.Fatalf("writeArtifactMetadata: %v", err)
+	}
+
+	data, err := os.ReadFile(filepath.Join(installDir, ".llar", "metadata.json"))
+	if err != nil {
+		t.Fatalf("read metadata.json: %v", err)
+	}
+	var raw map[string]json.RawMessage
+	if err := json.Unmarshal(data, &raw); err != nil {
+		t.Fatalf("metadata.json is invalid JSON: %v", err)
+	}
+	if _, ok := raw["metadata"]; !ok {
+		t.Fatal("metadata.json missing metadata field")
+	}
+	if _, ok := raw["deps"]; ok {
+		t.Fatalf("metadata.json contains deps for standalone artifact: %s", data)
+	}
+}
+
+func TestOutputArtifactCopiesMetadataDirectory(t *testing.T) {
+	src := setupTestSrcDir(t)
+	dest := filepath.Join(t.TempDir(), "out")
+
+	if err := outputArtifact(src, dest, "-lfoo", nil); err != nil {
+		t.Fatalf("outputArtifact: %v", err)
+	}
+
+	data, err := os.ReadFile(filepath.Join(dest, ".llar", "metadata.json"))
+	if err != nil {
+		t.Fatalf("read output metadata.json: %v", err)
+	}
+	var got artifactMetadata
+	if err := json.Unmarshal(data, &got); err != nil {
+		t.Fatalf("metadata.json is invalid JSON: %v", err)
+	}
+	if got.Metadata != "-lfoo" {
+		t.Fatalf("metadata = %q, want %q", got.Metadata, "-lfoo")
+	}
+}
+
+func TestOutputArtifactZipsMetadataDirectory(t *testing.T) {
+	src := setupTestSrcDir(t)
+	dest := filepath.Join(t.TempDir(), "out.zip")
+
+	if err := outputArtifact(src, dest, "-lfoo", nil); err != nil {
+		t.Fatalf("outputArtifact: %v", err)
+	}
+
+	r, err := zip.OpenReader(dest)
+	if err != nil {
+		t.Fatalf("open zip: %v", err)
+	}
+	defer r.Close()
+
+	for _, f := range r.File {
+		if f.Name != ".llar/metadata.json" {
+			continue
+		}
+		rc, err := f.Open()
+		if err != nil {
+			t.Fatalf("open metadata entry: %v", err)
+		}
+		defer rc.Close()
+		data, err := io.ReadAll(rc)
+		if err != nil {
+			t.Fatalf("read metadata entry: %v", err)
+		}
+		var got artifactMetadata
+		if err := json.Unmarshal(data, &got); err != nil {
+			t.Fatalf("metadata.json is invalid JSON: %v", err)
+		}
+		if got.Metadata != "-lfoo" {
+			t.Fatalf("metadata = %q, want %q", got.Metadata, "-lfoo")
+		}
+		return
+	}
+	t.Fatal("zip missing .llar/metadata.json")
+}
+
 func TestOutputResult_CopyDir(t *testing.T) {
 	src := setupTestSrcDir(t)
 	dest := filepath.Join(t.TempDir(), "out")