internal/rosa: do not hard code filename prefix

The hardcoded name is not correct for externally registered files.

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

3 files changed, 11 insertions, 4 deletions

diff --git a/cmd/mbf/main.go b/cmd/mbf/main.go
index 115ca1a2..eb250ec8 100644
--- a/cmd/mbf/main.go
+++ b/cmd/mbf/main.go
@@ -178,12 +178,17 @@ func main() {
 		}
 
 		if azaleaPath != "" {
+			prefix := azaleaPath
+			if prefix[len(prefix)-1] != '/' {
+				prefix += "/"
+			}
+
 			var root *os.Root
 			if a, err := check.NewAbs(azaleaPath); err != nil {
 				return err
 			} else if root, err = os.OpenRoot(a.String()); err != nil {
 				return err
-			} else if err = builtin.RegisterFS(root.FS()); err != nil {
+			} else if err = builtin.RegisterFS(root.FS(), prefix); err != nil {
 				return err
 			}
 		}
diff --git a/internal/rosa/builtins.go b/internal/rosa/builtins.go
index edca2333..bca69a03 100644
--- a/internal/rosa/builtins.go
+++ b/internal/rosa/builtins.go
@@ -135,7 +135,7 @@ func init() {
 		panic(err)
 	}
 	t := time.Now()
-	if err = builtin.RegisterFS(sub); err != nil {
+	if err = builtin.RegisterFS(sub, "internal/rosa/package/"); err != nil {
 		println(err.Error())
 		os.Exit(1)
 	}
diff --git a/internal/rosa/state.go b/internal/rosa/state.go
index dc1b3109..c236ee6d 100644
--- a/internal/rosa/state.go
+++ b/internal/rosa/state.go
@@ -1355,13 +1355,15 @@ func (s *S) RegisterAzalea(r io.Reader, name string, b fs.FS) error {
 // 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) RegisterFS(fsys fs.FS) error {
+//
+// The prefix string is only used for position information and must use forward
+// slashes as its path separator and end with a path separator.
+func (s *S) RegisterFS(fsys fs.FS, prefix string) error {
 	dents, err := fs.ReadDir(fsys, ".")
 	if err != nil {
 		return err
 	}
 
-	const prefix = "internal/rosa/package/"
 	var r fs.File
 	for _, dent := range dents {
 		if dent.IsDir() {