#define _GNU_SOURCE

#include <stdio.h>
#include <sched.h>
#include <sys/mount.h>
#include <unistd.h>

#define e(n,f) if (-1 == (f)) {perror(n);return(1);}
#define SRC "/glibc"

int main(int argc, const char const *argv[]) {
	const char const *shell[] = { "/bin/sh", NULL };

	/* move glibc stuff in place */
	e("unshare",unshare(CLONE_NEWNS));
	e("mount",mount(SRC "/usr", "/usr", NULL, MS_BIND, NULL));
	e("mount",mount(SRC "/opt", "/opt", NULL, MS_BIND, NULL));
	e("mount",mount(SRC "/var/db/xbps", "/var/db/xbps", NULL, MS_BIND, NULL));

	/* drop the rights suid gave us */
	e("setuid",setreuid(getuid(),getuid()));
	e("setgid",setregid(getgid(),getgid()));

	argv++;
	if (!argv[0]) argv = shell;
	e("execv",execvp(argv[0], argv));
}