internal/rosa: do not keep underlying file

No operation require further filesystem interaction for now.

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

internal/rosa/report.go

@@ -105,9 +105,9 @@ func WriteReport(msg message.Msg, w io.Writer, c *pkg.Cache) error {
 
 // Report provides efficient access to a report file populated by [WriteReport].
 type Report struct {
-	// Underlying file, must not be exposed directly.
+	// Slice backed by the underlying file.
-	f *os.File
+	//
-	// Slice backed by f. Access must be prepared by HandleAccess.
+	// Access must be prepared by HandleAccess.
 	data []byte
 
 	// Offsets into data for each identifier.
@@ -121,31 +121,31 @@ type Report struct {
 
 // OpenReport opens a file populated by [WriteReport]
 func OpenReport(pathname string) (rp *Report, err error) {
-	var r Report
+	var f *os.File
-	if r.f, err = os.Open(pathname); err != nil {
+	if f, err = os.Open(pathname); err != nil {
 		return
 	}
-	defer func() {
-		if err != nil {
-			_ = r.f.Close()
-			if r.data != nil {
-				_ = syscall.Munmap(r.data)
-			}
-		}
-	}()
 
 	var fi os.FileInfo
-	if fi, err = r.f.Stat(); err != nil {
+	if fi, err = f.Stat(); err != nil {
+		_ = f.Close()
 		return
 	}
 
+	var r Report
 	if r.data, err = syscall.Mmap(
-		int(r.f.Fd()),
+		int(f.Fd()),
 		0,
 		int(fi.Size()),
 		syscall.PROT_READ,
 		syscall.MAP_PRIVATE,
 	); err != nil {
+		_ = f.Close()
+		return
+	}
+
+	if err = f.Close(); err != nil {
+		_ = r.Close()
 		return
 	}
 
@@ -230,9 +230,6 @@ func (r *Report) ArtifactOf(id unique.Handle[pkg.ID]) (status []byte, n int64) {
 
 // Close closes the underlying file and releases all associated resources.
 func (r *Report) Close() error {
-	r.closeOnce.Do(func() {
+	r.closeOnce.Do(func() { r.closeErr = syscall.Munmap(r.data) })
-		err := syscall.Munmap(r.data)
-		r.closeErr = errors.Join(err, r.f.Close())
-	})
 	return r.closeErr
 }