bsd.c - utmp - simple login manager  
  HTML git clone git://git.suckless.org/utmp
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       ---
       bsd.c (1143B)
       ---
            1 
            2 #include <ctype.h>
            3 #include <errno.h>
            4 #include <stdlib.h>
            5 #include <string.h>
            6 
            7 #include <unistd.h>
            8 #include <util.h>
            9 #include <grp.h>
           10 #include <utmp.h>
           11 #include <pwd.h>
           12 
           13 extern void die(const char *fmt, ...);
           14 extern struct passwd *pw;
           15 extern gid_t egid, gid;
           16 static struct utmp utmp;
           17 
           18 void
           19 addutmp(void)
           20 {
           21         unsigned ptyid;
           22         char *pts, *cp, *host;
           23 
           24 
           25         if (!(host = getenv("DISPLAY")))
           26                 host = "-";
           27 
           28         if (strlen(pw->pw_name) > sizeof(utmp.ut_name))
           29                 die("utmp:incorrect username %s", pw->pw_name);
           30 
           31         if ((pts = ttyname(STDIN_FILENO)) == NULL)
           32                 die("utmp:error getting pty name:%s", strerror(errno));
           33 
           34         for (cp = pts + strlen(pts) - 1; isdigit(*cp); --cp)
           35                 /* nothing */;
           36 
           37         ptyid = atoi(++cp);
           38         if (ptyid > 999 || strlen(pts + 5) > sizeof(utmp.ut_line))
           39                 die("utmp:Incorrect pts name %s\n", pts);
           40 
           41         /* remove /dev/ from pts */
           42         strncpy(utmp.ut_line, pts + 5, sizeof(utmp.ut_line));
           43         strncpy(utmp.ut_name, pw->pw_name, sizeof(utmp.ut_name));
           44         strncpy(utmp.ut_host, host, sizeof(utmp.ut_host));
           45         time(&utmp.ut_time);
           46 
           47         setegid(egid);
           48         login(&utmp);
           49         setegid(gid);
           50 }
           51 
           52 void
           53 delutmp(void)
           54 {
           55         setgid(egid);
           56         logout(utmp.ut_line);
           57         setgid(gid);
           58 }
           59