BSD 4_1c_2 release

[unix-history] / usr / src / lib / libc / gen / ttyslot.c

/* @(#)ttyslot.c        4.1 (Berkeley) 12/21/80 */
/*
* Return the number of the slot in the utmp file
* corresponding to the current user: try for file 0, 1, 2.
* Definition is the line number in the /etc/ttys file.
*/


char    *ttyname();
char    *getttys();
char    *rindex();
static  char    ttys[]  = "/etc/ttys";

#define NULL    0

ttyslot()
{
       register char *tp, *p;
       register s, tf;

       if ((tp=ttyname(0))==NULL && (tp=ttyname(1))==NULL && (tp=ttyname(2))==NULL)
               return(0);
       if ((p = rindex(tp, '/')) == NULL)
               p = tp;
       else
               p++;
       if ((tf=open(ttys, 0)) < 0)
               return(0);
       s = 0;
       while (tp = getttys(tf)) {
               s++;
               if (strcmp(p, tp)==0) {
                       close(tf);
                       return(s);
               }
       }
       close(tf);
       return(0);
}

static char *
getttys(f)
{
       static char line[32];
       register char *lp;

       lp = line;
       for (;;) {
               if (read(f, lp, 1) != 1)
                       return(NULL);
               if (*lp =='\n') {
                       *lp = '\0';
                       return(line+2);
               }
               if (lp >= &line[32])
                       return(line+2);
               lp++;
       }
}