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

/*
* Copyright (c) 1987, 1993 Regents of the University of California.
* All rights reserved.
*
* %sccs.include.redist.c%
*/

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1987, 1993 Regents of the University of California.\n\
All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)mesg.c      5.4 (Berkeley) %G%";
#endif /* not lint */

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

#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

int
main(argc, argv)
       int argc;
       char *argv[];
{
       struct stat sb;
       char *tty;
       int ch;

       while ((ch = getopt(argc, argv, "")) != EOF)
               switch (ch) {
               case '?':
               default:
                       goto usage;
               }
       argc -= optind;
       argv += optind;

       if ((tty = ttyname(STDERR_FILENO)) == NULL)
               err(1, "ttyname");
       if (stat(tty, &sb) < 0)
               err(1, "%s", tty);

       if (*argv == NULL) {
               if (sb.st_mode & S_IWGRP) {
                       (void)fprintf(stderr, "is y\n");
                       exit(0);
               }
               (void)fprintf(stderr, "is n\n");
               exit(1);
       }

       switch (*argv[0]) {
       case 'y':
               if (chmod(tty, sb.st_mode | S_IWGRP) < 0)
                       err(1, "%s", tty);
               exit(0);
       case 'n':
               if (chmod(tty, sb.st_mode & ~S_IWGRP) < 0)
                       err(1, "%s", tty);
               exit(1);
       }

usage:  (void)fprintf(stderr, "usage: mesg [y | n]\n");
       exit(2);
}