fix: 修复写队列 busy 恢复、关闭安全、备份与配置构建问题

internal/store/migrate.go

@@ -18,9 +18,22 @@ var migrationFS embed.FS
 
 // Migrate 应用尚未执行的嵌入迁移。
 // 若 dbExisted 为 true（调用 Open/Migrate 前已有 nixmsg.db）且存在未应用版本，
-// 先 VACUUM INTO <data_dir>/backup/pre-migrate-<时间>.db，再迁移。
+// 先 VACUUM INTO <data_dir>/backup/pre-migrate-v{当前}-to-v{目标}.db，再迁移。
+// 备份文件已存在则复用，避免迁移稳定失败时反复全量复制。
 // 任一版本失败则返回错误，调用方不得继续带半新半旧库提供服务。
 func Migrate(db *sql.DB, dataDir string, dbExisted bool) error {
+	if err := ensureMigrationsTable(db); err != nil {
+		return err
+	}
+
+	pending, err := pendingMigrations(db)
+	if err != nil {
+		return err
+	}
+	return applyPending(db, dataDir, dbExisted, pending)
+}
+
+func ensureMigrationsTable(db *sql.DB) error {
 	if _, err := db.Exec(`
 CREATE TABLE IF NOT EXISTS schema_migrations (
   version INTEGER PRIMARY KEY,
@@ -28,17 +41,21 @@ CREATE TABLE IF NOT EXISTS schema_migrations (
 )`); err != nil {
 		return fmt.Errorf("ensure schema_migrations: %w", err)
 	}
+	return nil
+}
 
-	pending, err := pendingMigrations(db)
-	if err != nil {
-		return err
-	}
+func applyPending(db *sql.DB, dataDir string, dbExisted bool, pending []migrationFile) error {
 	if len(pending) == 0 {
 		return nil
 	}
 
 	if dbExisted {
-		if err := backupBeforeMigrate(db, dataDir); err != nil {
+		from, err := currentSchemaVersion(db)
+		if err != nil {
+			return err
+		}
+		to := pending[len(pending)-1].version
+		if err := backupBeforeMigrate(db, dataDir, from, to); err != nil {
 			return err
 		}
 	}
@@ -98,13 +115,33 @@ func pendingMigrations(db *sql.DB) ([]migrationFile, error) {
 	return pending, nil
 }
 
-func backupBeforeMigrate(db *sql.DB, dataDir string) error {
+func currentSchemaVersion(db *sql.DB) (int, error) {
+	var v sql.NullInt64
+	if err := db.QueryRow(`SELECT MAX(version) FROM schema_migrations`).Scan(&v); err != nil {
+		return 0, fmt.Errorf("current schema version: %w", err)
+	}
+	if !v.Valid {
+		return 0, nil
+	}
+	return int(v.Int64), nil
+}
+
+func backupBeforeMigrate(db *sql.DB, dataDir string, fromVer, toVer int) error {
 	backupDir := filepath.Join(dataDir, "backup")
 	if err := os.MkdirAll(backupDir, 0o755); err != nil {
 		return fmt.Errorf("mkdir backup: %w", err)
 	}
-	stamp := time.Now().UTC().Format("20060102T150405")
-	backupPath := filepath.Join(backupDir, "pre-migrate-"+stamp+".db")
+	backupPath := filepath.Join(backupDir, fmt.Sprintf("pre-migrate-v%d-to-v%d.db", fromVer, toVer))
+	exists, err := fileExists(backupPath)
+	if err != nil {
+		return err
+	}
+	if exists {
+		return nil
+	}
+	if err := ensureDiskSpace(backupDir, backupNeedBytes(dataDir)); err != nil {
+		return err
+	}
 	// SQLite VACUUM INTO 需要字面量路径；统一用斜杠，并对单引号转义。
 	quoted := strings.ReplaceAll(filepath.ToSlash(backupPath), "'", "''")
 	if _, err := db.Exec("VACUUM INTO '" + quoted + "'"); err != nil {
@@ -113,6 +150,34 @@ func backupBeforeMigrate(db *sql.DB, dataDir string) error {
 	return nil
 }
 
+func backupNeedBytes(dataDir string) int64 {
+	var n int64
+	for _, name := range []string{DBFileName, DBFileName + "-wal", DBFileName + "-shm"} {
+		st, err := os.Stat(filepath.Join(dataDir, name))
+		if err == nil {
+			n += st.Size()
+		}
+	}
+	return n
+}
+
+func ensureDiskSpace(dir string, need int64) error {
+	if need < 0 {
+		need = 0
+	}
+	avail, err := availableBytes(dir)
+	if err != nil {
+		// 探测失败不阻断迁移，VACUUM INTO 自身会因空间不足报错。
+		return nil
+	}
+	const margin = 1 << 20
+	want := uint64(need) + margin
+	if avail < want {
+		return fmt.Errorf("insufficient disk space for migrate backup: have %d bytes, need ~%d", avail, want)
+	}
+	return nil
+}
+
 func applyMigration(db *sql.DB, m migrationFile) error {
 	tx, err := db.Begin()
 	if err != nil {