ttyslot.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

/*	@(#)ttyslot.c	1.4	*/
/*	@(#)ttyslot.c	1.2	*/
/*LINTLIBRARY*/
/*
 * Return the number of the slot in the utmp file
 * corresponding to the current user: try for file 0, 1, 2.
 * Returns -1 if slot not found.
 */
#include <sys/types.h>
#include <utmp.h>	/* DAG -- not "utmp.h" */
#define	NULL	0

extern char *ttyname(), *strrchr();
extern int strncmp(), open(), read(), close();

int
ttyslot()
{
	struct utmp ubuf;
	register char *tp, *p;
	register int s, fd;

	if((tp=ttyname(0)) == NULL && (tp=ttyname(1)) == NULL &&
					(tp=ttyname(2)) == NULL)
		return(-1);

	if((p=strrchr(tp, '/')) == NULL)
		p = tp;
	else
		p++;

	if((fd=open(UTMP_FILE, 0)) < 0)
		return(-1);
	s = 0;
	while(read(fd, (char*)&ubuf, sizeof(ubuf)) == sizeof(ubuf)) {
		if(			/* no ut_type */
/* BRL			(ubuf.ut_type == INIT_PROCESS ||
			ubuf.ut_type == LOGIN_PROCESS ||
			ubuf.ut_type == USER_PROCESS ||
			ubuf.ut_type == DEAD_PROCESS ) &&
*/
			strncmp(p, ubuf.ut_line, sizeof(ubuf.ut_line)) == 0){

			(void) close(fd);
			return(s);
		}
		s++;
	}
	(void) close(fd);
	return(-1);
}