#include <stdio.h>#include <stdlib.h>#include <droppriv.h>int main(int ac, char *av[]) {	int uid, gid, status;	if(ac < 2) {		printf("usage: %s username [groupname]\n", av[0]);		exit(1);	}	uid = user2uid(av[1]);	if(uid == -2) {		printf("user %s does not exist\n", av[1]);		exit(1);	} else if(uid == -1) {		printf("couln't open /etc/passwd\n");		exit(1);	} else if(uid == -3) {		printf("ill-formatted line in /etc/passwd\n");		exit(1);	}	gid = user2gid(av[1]);	if(gid == -2) {		printf("user %s does not exist\n", av[1]);		exit(1);	} else if(gid == -1) {		printf("couln't open /etc/passwd\n");		exit(1);	} else if(gid == -3) {		printf("ill-formatted line in /etc/passwd\n");		exit(1);	}	printf("user %s has uid = %d gid = %d\n", av[1], uid, gid);	if(ac >= 3){		gid = group2gid(av[1]);		if(gid == -2) {			printf("user %s does not exist\n", av[1]);			exit(1);		} else if(gid == -1) {			printf("couln't open /etc/passwd\n");			exit(1);		} else if(gid == -3) {			printf("ill-formatted line in /etc/passwd\n");			exit(1);		}		printf("group %s is resolved to gid = %d\n", av[2], group2gid(av[2]));	}	/* now trying to drop root privilege */	#ifndef __WIN32__		if((status = droppriv(uid, gid)) != 0) {			printf("FATAL: Couldn't drop root privilege: ");			if(status == -1)				printf("suppl. group IDs reset to non-root GID failed\n");			else if(status == -2)				printf("couldn't change to non-privileged GID %d\n", gid);			else if(status == -3)				printf("couldn't change to non-root UID %d\n", uid);			else if(status == -4)				printf("once non-root, setuid(0) managed to restore root UID!\n");			exit(1);		}	#endif	return 0;}