UNIX 6th Ed. - /usr/source/s2/wall.c

   1: char    mesg[3000];
   2: int msize;
   3: struct
   4: {
   5:     char    name[8];
   6:     char    tty[2];
   7:     int time[2];
   8:     int junk;
   9: } utmp[50];
  10: 
  11: main(argc, argv)
  12: char *argv[];
  13: {
  14:     register i, *p;
  15:     int f;
  16: 
  17:     f = open("/etc/utmp", 0);
  18:     if(f < 0) {
  19:         printf("utmp?\n");
  20:         exit();
  21:     }
  22:     read(f, utmp, sizeof utmp);
  23:     close(f);
  24:     f = 0;
  25:     if(argc >= 2) {
  26:         f = open(argv[1], 0);
  27:         if(f < 0) {
  28:             printf("%s?\n", argv[1]);
  29:             exit();
  30:         }
  31:     }
  32:     while((i = read(f, &mesg[msize], sizeof mesg - msize)) > 0)
  33:         msize =+ i;
  34:     close(f);
  35:     for(i=0; i<sizeof utmp/sizeof utmp[0]; i++) {
  36:         p = &utmp[i];
  37:         if(p->tty[0] == 0)
  38:             continue;
  39:         sleep(1);
  40:         sendmes(p->tty[0]);
  41:     }
  42: }
  43: 
  44: sendmes(tty)
  45: {
  46:     register i;
  47:     register char *s;
  48: 
  49:     i = fork();
  50:     if(i == -1) {
  51:         printf("try again\n");
  52:         return;
  53:     }
  54:     if(i)
  55:         return;
  56:     s = "/dev/ttyx";
  57:     s[8] = tty;
  58:     i = open(s, 1);
  59:     if(i < 0) {
  60:         printf("cannot open tty%c\n", tty);
  61:         exit();
  62:     }
  63:     close(1);
  64:     dup(i);
  65:     printf("Broadcast Message ...\n\n");
  66:     write(1, mesg, msize);
  67:     exit();
  68: }

Defined functions

Defined variables