diplodocus.org Git - nmh/blob - docs/historical/mh-jun-1982/Extras/libg/ttynum.c

   1 #ifdef COMMENT
   2         Proprietary Rand Corporation, 1981.
   3         Further distribution of this software
   4         subject to the terms of the Rand
   5         license agreement.
   6 #endif
   7
   8 #include "../h/stat.h"
   9
  10 ttynum(name)
  11 char *name;
  12 {
  13         /* this routine returns the internal number */
  14         /* of the given tty name (string) */
  15         /* if the name="tty" or "", the number is that */
  16         /* of the user's tty. */
  17         /* this is obviously very system dependent */
  18         register int major, minor, flags;
  19         struct inode ibuf;
  20         struct { char low, high; };
  21
  22         if (*name == '\0' || equal(name,"tty")) {
  23                 if (fstat(2,&ibuf) < 0 &&
  24                     fstat(1,&ibuf) < 0) return(-1);
  25         }
  26         else
  27         if (stat(cat("/dev/",name),&ibuf) < 0 &&
  28             stat(cat("/dev/tty",name),&ibuf) < 0) return(-1);
  29         flags = ibuf.i_mode;
  30         if ((flags & IFMT) != IFCHR) return(-1);
  31         minor = ibuf.i_addr[0].low;
  32         major = ibuf.i_addr[0].high;
  33         if (major == 0)
  34                 return(minor);
  35         else
  36         if (major == 1)
  37                 return(minor+1);
  38         else
  39         return (-1);
  40 }