Release vtable and cursor handles when SQLite destroys them

callback.go

@@ -131,6 +131,27 @@ func lookupHandle(handle unsafe.Pointer) any {
 	return lookupHandleVal(handle).val
 }
 
+// deleteHandle releases a single handle created by newHandle. It is a no-op
+// if the handle is unknown (e.g. already released).
+func deleteHandle(handle unsafe.Pointer) {
+	handleLock.Lock()
+	defer handleLock.Unlock()
+
+	current := loadHandleVals()
+	if _, ok := current[handle]; !ok {
+		return
+	}
+	next := make(map[unsafe.Pointer]handleVal, len(current)-1)
+	for h, v := range current {
+		if h == handle {
+			continue
+		}
+		next[h] = v
+	}
+	handleVals.Store(next)
+	C.free(handle)
+}
+
 func deleteHandles(db *SQLiteConn) {
 	handleLock.Lock()
 	defer handleLock.Unlock()

sqlite3_opt_vtable.go

@@ -423,6 +423,9 @@ func goVRelease(pVTab unsafe.Pointer, isDestroy C.int) *C.char {
 	} else {
 		err = vt.vTab.Disconnect()
 	}
+	// The vtab is gone as far as SQLite is concerned regardless of the
+	// callback result, so release the handle either way.
+	deleteHandle(pVTab)
 	if err != nil {
 		return mPrintf("%s", err.Error())
 	}
@@ -492,6 +495,9 @@ func goVBestIndex(pVTab unsafe.Pointer, icp unsafe.Pointer) *C.char {
 func goVClose(pCursor unsafe.Pointer) *C.char {
 	vtc := lookupHandle(pCursor).(*sqliteVTabCursor)
 	err := vtc.vTabCursor.Close()
+	// The cursor is gone as far as SQLite is concerned regardless of the
+	// callback result, so release the handle either way.
+	deleteHandle(pCursor)
 	if err != nil {
 		return mPrintf("%s", err.Error())
 	}
@@ -502,6 +508,7 @@ func goVClose(pCursor unsafe.Pointer) *C.char {
 func goMDestroy(pClientData unsafe.Pointer) {
 	m := lookupHandle(pClientData).(*sqliteModule)
 	m.module.DestroyModule()
+	deleteHandle(pClientData)
 }
 
 //export goVFilter

sqlite3_opt_vtable_leak_test.go

@@ -0,0 +1,38 @@
+//go:build sqlite_vtable
+
+package sqlite3
+
+import (
+	"database/sql"
+	"testing"
+)
+
+func TestVtabCursorHandleRelease(t *testing.T) {
+	sql.Register("sqlite3_HandleLeakCheck", &SQLiteDriver{
+		ConnectHook: func(conn *SQLiteConn) error {
+			return conn.CreateModule("test", &testModule{t: t, intarray: []int{1, 2, 3}})
+		},
+	})
+	db, err := sql.Open("sqlite3_HandleLeakCheck", ":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+	if _, err := db.Exec("CREATE VIRTUAL TABLE vtab USING test('1', 2, three)"); err != nil {
+		t.Fatal(err)
+	}
+	var before, after int
+	for i := 0; i < 50; i++ {
+		var n int
+		if err := db.QueryRow("SELECT count(*) FROM vtab").Scan(&n); err != nil {
+			t.Fatal(err)
+		}
+		if i == 0 {
+			before = len(loadHandleVals())
+		}
+	}
+	after = len(loadHandleVals())
+	if after > before {
+		t.Fatalf("handle map grew from %d to %d over repeated cursor open/close", before, after)
+	}
+}