Anonymous, public, read-only access to the code in CVS is available. Here are the basic instructions for Unix systems:
cvs -d:pserver:anonymous@cvs.mesa3d.sourceforge.net:/cvsroot/mesa3d
login
CVS password:
prompt.
cvs -z3 -d:pserver:anonymous@cvs.mesa3d.sourceforge.net:/cvsroot/mesa3d
co Mesa
To update your Mesa CVS source to the latest CVS source:
cd Mesa
cvs -z3 -d:pserver:anonymous@cvs.mesa3d.sourceforge.net:/cvsroot/mesa3d
update
You can browse the Mesa source code in CVS here.