static void extract_cgroup(ProcessHandle sandbox) {
	int fd = process_rootfs_open(sandbox, RUN_CGROUP_CFG);
	if (fd < 0)
		return; // not configured

	FILE *fp = fdopen(fd, "r");
	if (!fp)
		errExit("fdopen");

	char buf[BUFLEN];
	if (fgets(buf, BUFLEN, fp)) {
		cfg.cgroup = strdup(buf);
		if (!cfg.cgroup)
			errExit("strdup");
	}
	fclose(fp);
}
static void extract_cgroup(ProcessHandle sandbox) {
	int fd = process_rootfs_open(sandbox, RUN_CGROUP_CFG);
	if (fd < 0)
		return;  

	FILE *fp = fdopen(fd, "r");
	if (!fp)
		errExit("fdopen");

	char buf[BUFLEN];
	if (fgets(buf, BUFLEN, fp)) {
		cfg.cgroup = strdup(buf);
		if (!cfg.cgroup)
			errExit("strdup");
	}
	fclose(fp);
}