modestly extend SQLite support (#8677)

This is primarily to unblock the advanced permissions merge. There's
still more work to do if we wanted this to be mainstream, but as it's
mainly for unit tests, I'm just focussing on the minimum.

store/sqlstore/supplier.go

@@ -61,6 +61,8 @@ const (
 	EXIT_REMOVE_TABLE                = 134
 	EXIT_CREATE_INDEX_SQLITE         = 135
 	EXIT_REMOVE_INDEX_SQLITE         = 136
+	EXIT_TABLE_EXISTS_SQLITE         = 137
+	EXIT_DOES_COLUMN_EXISTS_SQLITE   = 138
 )
 
 type SqlSupplierOldStores struct {
@@ -365,6 +367,20 @@ func (ss *SqlSupplier) DoesTableExist(tableName string) bool {
 
 		return count > 0
 
+	} else if ss.DriverName() == model.DATABASE_DRIVER_SQLITE {
+		count, err := ss.GetMaster().SelectInt(
+			`SELECT name FROM sqlite_master WHERE type='table' AND name=?`,
+			tableName,
+		)
+
+		if err != nil {
+			l4g.Critical(utils.T("store.sql.table_exists.critical"), err)
+			time.Sleep(time.Second)
+			os.Exit(EXIT_TABLE_EXISTS_SQLITE)
+		}
+
+		return count > 0
+
 	} else {
 		l4g.Critical(utils.T("store.sql.column_exists_missing_driver.critical"))
 		time.Sleep(time.Second)
@@ -420,6 +436,21 @@ func (ss *SqlSupplier) DoesColumnExist(tableName string, columnName string) bool
 
 		return count > 0
 
+	} else if ss.DriverName() == model.DATABASE_DRIVER_SQLITE {
+		count, err := ss.GetMaster().SelectInt(
+			`SELECT COUNT(*) FROM pragma_table_info(?) WHERE name=?`,
+			tableName,
+			columnName,
+		)
+
+		if err != nil {
+			l4g.Critical(utils.T("store.sql.column_exists.critical"), err)
+			time.Sleep(time.Second)
+			os.Exit(EXIT_DOES_COLUMN_EXISTS_SQLITE)
+		}
+
+		return count > 0
+
 	} else {
 		l4g.Critical(utils.T("store.sql.column_exists_missing_driver.critical"))
 		time.Sleep(time.Second)