CVS_PATH_DEVNULL
cvs_printf("%s ", CVS_PATH_DEVNULL);
if ((fd1 = open(CVS_PATH_DEVNULL, O_RDONLY)) == -1)
fatal("cannot open %s", CVS_PATH_DEVNULL);
if ((fd2 = open(CVS_PATH_DEVNULL, O_RDONLY)) == -1)
fatal("cannot open %s", CVS_PATH_DEVNULL);
if (diffreg(p1 != NULL ? cf->file_path : CVS_PATH_DEVNULL,
p2 != NULL ? cf->file_path : CVS_PATH_DEVNULL, fd1, fd2, NULL,
diff_output("%s", CVS_PATH_DEVNULL);