commands/reboot/sh_wall.c

   1 /* wall - write to all logged in users                  Author: V. Archer */
   2 /*
   3    Edvard Tuinder    v892231@si.hhs.NL
   4     Modified some things to include this with my shutdown/halt
   5     package
   6  */
   7
   8 #define _POSIX_SOURCE   1
   9 #include <sys/types.h>
  10 #include <fcntl.h>
  11 #include <pwd.h>
  12 #include <string.h>
  13 #include <stdio.h>
  14 #include <time.h>
  15 #include <utmp.h>
  16 #include <unistd.h>
  17 #include <sys/utsname.h>
  18 #include <sys/stat.h>
  19 #undef UTMP
  20
  21 static char UTMP[] = "/etc/utmp";       /* Currently logged in users. */
  22
  23 void wall _ARGS(( char *when, char *extra ));
  24 void crnlcat _ARGS(( char *message, char *more ));
  25
  26 void
  27 wall(when, extra)
  28 char *when;                     /* When is shutdown */
  29 char *extra;                    /* If non-nil, why is the shutdown */
  30 {
  31   struct utmp utmp;
  32   char utmptty[5 + sizeof(utmp.ut_line) + 1];
  33   char message[1024];
  34   struct passwd *pw;
  35   int utmpfd, ttyfd;
  36   char *ourtty, *ourname;
  37   time_t now;
  38   struct utsname utsname;
  39   struct stat con_st, tty_st;
  40
  41   if ((ourtty = ttyname(1))) {
  42         if ((ourname = strrchr(ourtty, '/'))) ourtty = ourname+1;
  43   } else ourtty = "system task";
  44   if ((pw = getpwuid(getuid()))) ourname = pw->pw_name;
  45   else ourname = "unknown";
  46
  47   time(&now);
  48   if (uname(&utsname) != 0) strcpy(utsname.nodename, "?");
  49   sprintf(message, "\r\nBroadcast message from %s@%s (%s)\r\n%.24s...\r\n",
  50                 ourname, utsname.nodename, ourtty, ctime(&now));
  51
  52   crnlcat(message, when);
  53   crnlcat(message, extra);
  54
  55 /* Search the UTMP database for all logged-in users. */
  56
  57   if ((utmpfd = open(UTMP, O_RDONLY)) < 0) {
  58         fprintf(stderr, "Cannot open utmp file\r\n");
  59         return;
  60   }
  61
  62   /* first the console */
  63   strcpy(utmptty, "/dev/console");
  64   if ((ttyfd = open(utmptty, O_WRONLY | O_NONBLOCK)) < 0) {
  65         perror(utmptty);
  66   } else {
  67         fstat(ttyfd, &con_st);
  68         write(ttyfd, message, strlen(message));
  69         close(ttyfd);
  70   }
  71
  72   while (read(utmpfd, (char *) &utmp, sizeof(utmp)) == sizeof(utmp)) {
  73         /* is this the user we are looking for? */
  74         if (utmp.ut_type != USER_PROCESS) continue;
  75
  76         strncpy(utmptty+5, utmp.ut_line, sizeof(utmp.ut_line));
  77         utmptty[5 + sizeof(utmp.ut_line) + 1] = 0;
  78         if ((ttyfd = open(utmptty, O_WRONLY | O_NONBLOCK)) < 0) {
  79                 perror(utmptty);
  80                 continue;
  81         }
  82         fstat(ttyfd, &tty_st);
  83         if (tty_st.st_rdev != con_st.st_rdev)
  84                 write(ttyfd, message, strlen(message));
  85         close(ttyfd);
  86   }
  87   close(utmpfd);
  88   return;
  89 }
  90
  91 void
  92 crnlcat(message, more)
  93 char *message, *more;
  94 {
  95   char *p = message;
  96   char *m = more;
  97   char *end = message + 1024 - 1;
  98
  99   while (p < end && *p != 0) p++;
 100
 101   while (p < end && *m != 0) {
 102     if (*m == '\n' && (p == message || p[-1] != '\n')) {
 103       *p++ = '\r';
 104       if (p == end) p--;
 105     }
 106     *p++ = *m++;
 107   }
 108   *p = 0;
 109 }