Refactor file handles.

internal/util/handle.go

@@ -0,0 +1,60 @@
+package util
+
+import (
+	"context"
+	"io"
+)
+
+type handleKey struct{}
+type handleState struct {
+	handles []any
+}
+
+func NewContext(ctx context.Context) (context.Context, io.Closer) {
+	state := new(handleState)
+	return context.WithValue(ctx, handleKey{}, state), state
+}
+
+func (s *handleState) Close() (err error) {
+	for _, h := range s.handles {
+		if c, ok := h.(io.Closer); ok {
+			if e := c.Close(); err == nil {
+				err = e
+			}
+		}
+	}
+	s.handles = nil
+	return err
+}
+
+func GetHandle(ctx context.Context, id uint32) any {
+	s := ctx.Value(handleKey{}).(*handleState)
+	return s.handles[id]
+}
+
+func DelHandle(ctx context.Context, id uint32) error {
+	s := ctx.Value(handleKey{}).(*handleState)
+	a := s.handles[id]
+	s.handles[id] = nil
+	if c, ok := a.(io.Closer); ok {
+		return c.Close()
+	}
+	return nil
+
+}
+
+func AddHandle(ctx context.Context, a any) (id uint32) {
+	s := ctx.Value(handleKey{}).(*handleState)
+
+	// Find an empty slot.
+	for id, h := range s.handles {
+		if h == nil {
+			s.handles[id] = a
+			return uint32(id)
+		}
+	}
+
+	// Add a new slot.
+	s.handles = append(s.handles, a)
+	return uint32(len(s.handles) - 1)
+}