#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

void dump()
{
	struct stat s;

	printf("uid: %d, euid: %d, gid: %d, egid: %d\n"
	       "getting file status...\n",
	       getuid(), geteuid(), getgid(), getegid());
	if (lstat("/etc", &s) == -1) {
		perror("lstat");
		exit(2);
	}
	printf("dev: %x, ino: %lld, mode: %04o\n"
	       "nlink: %d, uid: %d, gid: %d\n"
	       "rdev: %x, size: %ld, blksize: %d, blocks: %d\n"
	       "atime: %ld, mtime: %ld, ctime: %ld\n",
	       s.st_dev, s.st_ino, s.st_mode,
	       s.st_nlink, s.st_uid, s.st_gid,
	       s.st_rdev, s.st_size, s.st_blksize, s.st_blocks,
	       s.st_atime, s.st_mtime, s.st_ctime);
}

int main()
{
	dump();
	printf("changing effective user id...\n");
	if (seteuid(2113) == -1) {
		perror("seteuid");
		exit(2);
	}
	dump();
	return 0;
}