#include <stdio.h>
#include <errno.h>
#include <stdlib.h>

int main(int argc, char **argv)
{
	int uid;
	char *dir, **command, *end;
	
	if(argc < 3){
		fprintf(stderr, "Usage - do-chroot dir uid "
                  "command-line...\n");
		exit(1);
	}

	dir = argv[1];
	uid = strtoul(argv[2], &end, 10);
	if(*end != '\0'){
		fprintf(stderr, "the uid \"%s\" isn't a number\n", \
                  argv[2]);
		exit(1);
	}
	command = &argv[3];

	if(chdir(dir) < 0){
		perror("chroot");
		exit(1);
	}

	if(chroot(".") < 0){
		perror("chroot");
		exit(1);
	}

	if(setuid(uid) < 0){
		perror("setuid");
		exit(1);
	}

	execv(command[0], command);
	perror("execv");
	exit(1);
}