BSD 4 release

[unix-history] / usr / src / cmd / mesg.c

static char *sccsid = "@(#)mesg.c       4.2 (Berkeley) 10/18/80";
/*
* mesg -- set current tty to accept or
*      forbid write permission.
*
*      mesg [y] [n]
*              y allow messages
*              n forbid messages
*/

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>

struct stat sbuf;

char *tty;
char *ttyname();

main(argc, argv)
char *argv[];
{
       int r=0;
       tty = ttyname(2);
       if (tty == 0)
               exit(13);
       if(stat(tty, &sbuf) < 0) error("cannot stat");
       if(argc < 2) {
               if(sbuf.st_mode & 02)
                       fprintf(stderr,"is y\n");
               else {  r=1;
                       fprintf(stderr,"is n\n");
               }
       } else  switch(*argv[1]) {
               case 'y':
                       newmode(sbuf.st_mode|022); break;

               case 'n':
                       newmode(sbuf.st_mode&~022); r=1; break;

               default:
                       error("usage: mesg [y] [n]");
               }
       exit(r);
}

error(s)
char *s;
{
       fprintf(stderr,"mesg: %s\n",s);
       exit(-1);
}

newmode(m)
{
       if(chmod(tty,m)<0)
               error("cannot change mode");
}