/* getlogin.c - poe@daimi.aau.dk */

#include <sys/types.h>
#include <fcntl.h>
#include <utmp.h>
#include <unistd.h>
#include <memory.h>
#include <pwd.h>
#if 0
#include "pathnames.h"
#endif

static char name[UT_NAMESIZE + 1];

char *ttyname(int);

/* return logname of the user of "this" tty */
char *getlogin(void)
{
	char *ttyn;
	struct utmp ut;
	int fd;
	
	if(!(ttyn = ttyname(0)) && !(ttyn = ttyname(1))
			&& !(ttyn = ttyname(2)))
		return (char *)0;

	/* we cannot use the getutline() function, 'cause that
	   would prohibit interleavig of getlogin() and getut...()
	   functions, eg. in write(1) */
	
	if((fd = open(_PATH_UTMP, O_RDONLY)) >= 0) {
		while(read(fd, (char *)&ut, sizeof(ut)) == sizeof(ut)) {
			if(!strncmp(ttyn + 5, ut.ut_line, sizeof(ut.ut_line))
				&& ut.ut_type == USER_PROCESS) {
				strncpy(name, ut.ut_user, UT_NAMESIZE);
				name [UT_NAMESIZE] = '\0';
				close(fd);
#if 0
				if (getpwnam(name))
					return name;
#else
				return name;
#endif
			}
		}
		close(fd);
	}
	return (char *)0;
}

#ifdef DEBUGGING
main()
{
	puts(getlogin());
}
#endif