internal/rosa: evaluate packages from fs

This migrates GNU sed to azalea, and resulting IR matches.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/mbf/main.go

@@ -64,11 +64,11 @@ func main() {
 			return
 		}
 
-		h, ok := r.(rosa.HandleError)
+		e, ok := r.(rosa.LoadError)
 		if !ok {
 			panic(r)
 		}
-		log.Fatal(h)
+		log.Fatal(e)
 	}()
 
 	ctx, stop := signal.NotifyContext(context.Background(),

internal/rosa/gnu.go

@@ -109,33 +109,6 @@ func init() {
 	})
 }
 
-func (t Toolchain) newSed() (pkg.Artifact, string) {
-	const (
-		version  = "4.10"
-		checksum = "TXTRFQJCyflb-bpBRI2S5Y1DpplwvT7-KfXtpqN4AdZgZ5OtI6yStn1-bkhDKx51"
-	)
-	return t.NewPackage("sed", version, newTar(
-		"https://ftpmirror.gnu.org/gnu/sed/sed-"+version+".tar.gz",
-		checksum,
-		pkg.TarGzip,
-	), nil, (*MakeHelper)(nil),
-		Diffutils,
-
-		KernelHeaders,
-	), version
-}
-func init() {
-	native.MustRegister(&Artifact{
-		f: Toolchain.newSed,
-
-		Name:        "sed",
-		Description: "a non-interactive command-line text editor",
-		Website:     "https://www.gnu.org/software/sed/",
-
-		ID: 4789,
-	})
-}
-
 func (t Toolchain) newAutoconf() (pkg.Artifact, string) {
 	const (
 		version  = "2.73"

internal/rosa/package/gnu/package.az

@@ -0,0 +1,22 @@
+// GNU software with trivial packaging.
+
+package sed {
+	description = "a non-interactive command-line text editor";
+	website = "https://www.gnu.org/software/sed";
+	anitya = 4789;
+
+	version* = "4.10";
+	source = remoteTar {
+		url = "https://ftpmirror.gnu.org/gnu/sed/sed-"+version+".tar.gz";
+		checksum = "TXTRFQJCyflb-bpBRI2S5Y1DpplwvT7-KfXtpqN4AdZgZ5OtI6yStn1-bkhDKx51";
+		compress = gzip;
+	};
+
+	exec = make {};
+
+	inputs = [
+		diffutils,
+
+		kernel-headers,
+	];
+}

internal/rosa/rosa.go

@@ -2,6 +2,9 @@
 package rosa
 
 import (
+	"embed"
+	"io/fs"
+	"os"
 	"path"
 	"slices"
 	"strconv"
@@ -608,3 +611,20 @@ var native S
 
 // Native returns the global [S].
 func Native() *S { return &native }
+
+// nativeB is the backing directory of built-in azalea-based [Artifact]
+// implementations.
+//
+//go:embed package
+var nativeB embed.FS
+
+func init() {
+	sub, err := fs.Sub(nativeB, "package")
+	if err != nil {
+		panic(err)
+	}
+	if err = native.EvaluateFS(sub); err != nil {
+		println(err)
+		os.Exit(1)
+	}
+}

internal/rosa/state.go

@@ -52,7 +52,7 @@ func (handle *ArtifactH) UnmarshalJSON(data []byte) error {
 type HandleError ArtifactH
 
 func (e HandleError) Error() string {
-	return "artifact " + strconv.Quote(ArtifactH(e).String()) + " not available"
+	return "package " + strconv.Quote(ArtifactH(e).String()) + " not available"
 }
 
 type (
@@ -268,8 +268,38 @@ func (s *S) New(stage Stage) Toolchain {
 // Std is a convenience method that returns a [Toolchain] for the [Std] stage.
 func (s *S) Std() Toolchain { return s.New(Std) }
 
+// LoadError wraps panicked errors reaching [Toolchain.Load].
+type LoadError struct {
+	// Offending artifact handle.
+	Handle ArtifactH
+	// Recovered error.
+	Err error
+}
+
+func (e LoadError) Unwrap() error { return e.Err }
+func (e LoadError) Error() string {
+	return "cannot load " + strconv.Quote(e.Handle.String()) + ": " + e.Err.Error()
+}
+
 // Load returns the resulting [pkg.Artifact] of [ArtifactH].
 func (t Toolchain) Load(handle ArtifactH) (pkg.Artifact, string) {
+	defer func() {
+		r := recover()
+		if r == nil {
+			return
+		}
+
+		err, ok := r.(error)
+		if !ok {
+			panic(r)
+		}
+
+		if _, ok = err.(LoadError); ok {
+			panic(err)
+		}
+		panic(LoadError{handle, err})
+	}()
+
 	t.wantsArch()
 	e, ok := t.c[t.stage].Load(handle)
 	if ok {
@@ -552,6 +582,64 @@ func (s *S) Evaluate(r io.Reader, b fs.FS) error {
 	return nil
 }
 
+// EvaluateFS evaluates azalea files discovered in fsys. A file is evaluated if
+// it is at the top level and its name has the suffix ".az", or it is in a
+// top-level directory with the exact file name "package.az". The backing
+// filesystem is directly exposed to azalea pathnames.
+func (s *S) EvaluateFS(fsys fs.FS) error {
+	dents, err := fs.ReadDir(fsys, ".")
+	if err != nil {
+		return err
+	}
+
+	var r fs.File
+	for _, dent := range dents {
+		if dent.IsDir() {
+			var sub fs.FS
+			sub, err = fs.Sub(fsys, dent.Name())
+			if err != nil {
+				return err
+			}
+
+			r, err = sub.Open("package.az")
+			if errors.Is(err, fs.ErrNotExist) {
+				continue
+			}
+			if err != nil {
+				return err
+			}
+
+			err = s.Evaluate(r, sub)
+			if _err := r.Close(); err == nil {
+				err = _err
+			}
+			if err != nil {
+				return err
+			}
+			continue
+		}
+
+		if !dent.Type().IsRegular() ||
+			!strings.HasSuffix(dent.Name(), ".az") {
+			continue
+		}
+
+		r, err = fsys.Open(dent.Name())
+		if err != nil {
+			return err
+		}
+
+		err = s.Evaluate(r, fsys)
+		if _err := r.Close(); err == nil {
+			err = _err
+		}
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // SetGentooStage3 sets the Gentoo stage3 tarball url and checksum. It panics
 // if given zero values or if these values have already been set.
 func (s *S) SetGentooStage3(url string, checksum pkg.Checksum) {