#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <fcntl.h>
#include <string.h>
#include <stdint.h>
#include <signal.h>
#include <errno.h>
#include <sys/wait.h>

int delete_mod = 0;

static int run_as(uid_t uid, gid_t gid, const char *path, char *const argv[])
{
    int i = 0;
    fprintf(stderr, "execing: ");
    while (argv[i]) {
	fprintf(stderr, "%s ", argv[i]);
	i++;
    }
    fprintf(stderr, "\n");

    /* Make sure we run as the full user.  If we're
     * switching to a non-root user, this won't allow
     * that process to switch back to root (since the
     * original process is setuid). */
    if (setresgid (gid, gid, gid) < 0) {
	perror("setresgid");
	exit(1);
    }
    if (setresuid (uid, uid, uid) < 0) {
	perror("setresuid");
	exit(1);
    }

    /* Actually run the command. */
    if (execv(path, argv) < 0)
	perror(path);
    _exit(1);
    return -1;
}


int main(int argc, char **argv)
{
    char *prog = argv[0];
    char *newargv[2];

    if (argc > 1)
	delete_mod = 1;

    fprintf(stderr, "%s: uid = %d, euid = %d\n", prog, (int)getuid(),
	    (int)geteuid());
    if (geteuid() != 0) {
	fprintf(stderr, "%s: ERROR - The effective user ID isn't root!\n",
		prog);
	exit(1);
    }

    if (delete_mod)
	exit(0);

    newargv[0] = "./test2";
    newargv[1] = NULL;
    if (run_as (getuid(), getgid(), newargv[0], newargv) < 0) {
	perror(argv[0]);
	return 1;
    }
    return 0;
}