def getfullnameof(mod, xtrapath=None):
    """
    Return the full path name of MOD.

    MOD is the basename of a dll or pyd.
    XTRAPATH is a path or list of paths to search first.
    Return the full path name of MOD.
    Will search the full Windows search path, as well as sys.path
    """
    # Search sys.path first!
    epath = sys.path + winutils.get_system_path()
    if xtrapath is not None:
        if type(xtrapath) == type(''):
            epath.insert(0, xtrapath)
        else:
            epath = xtrapath + epath
    for p in epath:
        npth = os.path.join(p, mod)
        if os.path.exists(npth):
            return npth
        # second try: lower case filename
        for p in epath:
            npth = os.path.join(p, mod.lower())
            if os.path.exists(npth):
                return npth
    return ''
Return the full path name of MOD.

    MOD is the basename of a dll or pyd.
    XTRAPATH is a path or list of paths to search first.
    Return the full path name of MOD.
    Will search the full Windows search path, as well as sys.path