+
+ int fd = open("/", O_DIRECTORY|O_PATH);
+ if (fd < 0) {
+ fprintf(stderr, "unable to open prefix directory: %m\n");
+ return 1;
+ }
+
+ if (chroot(".") < 0) {
+ fprintf(stderr, "failed to chroot: %m\n");
+ return 1;
+ }
+
+ if (fchdir(fd) == -1) {
+ fprintf(stderr, "failed to chdir to prefix directory: %m\n");
+ return 1;
+ }
+ close(fd);
+
+ if (argc != 3) {
+ fprintf(stderr, "sysupgrade stage 2 failed, invalid command line\n");
+ return 1;