Support overriding the database file.

main.go

@@ -39,6 +39,7 @@ func usage() {
 
 var (
 	debuglog = flag.String("debuglog", "", "a file to write debug log to")
+	dbname   = flag.String("db", "", "path to the database")
 	help     = flag.Bool("help", false, "show usage help and quit")
 )
 
@@ -212,7 +213,11 @@ func newEvalerAndStore() (*eval.Evaler, *store.Store) {
 
 	var st *store.Store
 	if err == nil {
-		st, err = store.NewStore(dataDir)
+		db := *dbname
+		if db == "" {
+			db = dataDir + "/db"
+		}
+		st, err = store.NewStore(db)
 		if err != nil {
 			fmt.Fprintln(os.Stderr, "Warning: cannot connect to store:", err)
 		}

store/store.go

@@ -17,15 +17,15 @@ type Store struct {
 var initTable = map[string](func(*sql.DB) error){}
 
 // DefaultDB returns the default database for storage.
-func DefaultDB(dataDir string) (*sql.DB, error) {
-	uri := "file:" + url.QueryEscape(dataDir+"/db") +
+func DefaultDB(dbname string) (*sql.DB, error) {
+	uri := "file:" + url.QueryEscape(dbname) +
 		"?mode=rwc&cache=shared&vfs=unix-dotfile"
 	return sql.Open("sqlite3", uri)
 }
 
 // NewStore creates a new Store with the default database.
-func NewStore(dataDir string) (*Store, error) {
-	db, err := DefaultDB(dataDir)
+func NewStore(dbname string) (*Store, error) {
+	db, err := DefaultDB(dbname)
 	if err != nil {
 		return nil, err
 	}