I'm programming on a c project and use code from another author. I change the main functionality to a new, complete other one. The most of the new code is my own but some files are untouched and others are modified.
Every file of the other author begins like this:
/* * Copyright (C) 2005 - authors name <firstname.lastname@example.org> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
1) Could I use GPL V3 and my own copyright for the main project (with or without naming the other author)?
2) How should be the header of files with fewer changes (like adding little functions and rename classes)?
3) One file is the original without changes. Should I left it as it is or should I update the GPL to V3 and add my copyright (with or without deleting the other authors name)?