[DERBY-6927] SystemProcedures.hasSchema can fail to close the resultset.

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 10.12.1.1
• Component/s: Services
• Assignee: Unassigned
• Reporter: Hao Zhong
• Created: 22/Mar/17 01:26
• Updated: 25/Mar/17 14:59

Description

The SystemProcedures.hasSchema method has the following code:

SystemProcedures.java

 ResultSet rs = conn.getMetaData().getSchemas();
        boolean schemaFound = false;
        while (rs.next() && !schemaFound)
            schemaFound = schemaName.equals(rs.getString("TABLE_SCHEM"));
        rs.close();

The while statement can throw exceptions, so the rs.close can never be executed. Indeed, DERBY-6297 fixed a similar bug. The buggy code is:

AccessDatabase.java

boolean found=false;
    	ResultSet result = conn.getMetaData().getSchemas();
    	while(result.next()){
    		if(result.getString(1).equals(schema)){
    			found=true;
    			break;
    		}
    	}	
    	return found;

The fixed code ensures that result is closed:

AccessDatabase.java

ResultSet result = conn.getMetaData().getSchemas();
        try {
            while (result.next()) {
                if (result.getString(1).equals(schema)) {
                    // Found it!
                    return true;
                }
            }
        } finally {
            result.close();
        }

        // Didn't find the schema.
        return false;