usr/src/usr.bin/mesg/mesg.c

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

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

#ifndef lint
static char sccsid[] = "@(#)mesg.c      5.1 (Berkeley) %G%";
#endif /* not lint */

#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static void err __P((const char *fmt, ...));
static void usage __P((void));

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

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

        if (!(tty = ttyname(2)))
                err("ttyname: %s", strerror(errno));
        if (stat(tty, &sbuf) < 0)
                err("%s: %s", strerror(errno));

        if (*argv == NULL) {
                if (sbuf.st_mode & 020) {
                        (void)fprintf(stderr, "is y\n");
                        exit(0);
                }
                (void)fprintf(stderr, "is n\n");
                exit(1);
        }
#define OTHER_WRITE     020
        switch(*argv[0]) {
        case 'y':
                if (chmod(tty, sbuf.st_mode | OTHER_WRITE) < 0)
                        err("%s: %s", strerror(errno));
                exit(0);
        case 'n':
                if (chmod(tty, sbuf.st_mode &~ OTHER_WRITE) < 0)
                        err("%s: %s", strerror(errno));
                exit(1);
        }
        usage();
        /* NOTREACHED */
}

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

#if __STDC__
#include <stdarg.h>
#else
#include <varargs.h>
#endif

void
#if __STDC__
err(const char *fmt, ...)
#else
err(fmt, va_alist)
        char *fmt;
        va_dcl
#endif
{
        va_list ap;
#if __STDC__
        va_start(ap, fmt);
#else
        va_start(ap);
#endif
        (void)fprintf(stderr, "mesg: ");
        (void)vfprintf(stderr, fmt, ap);
        va_end(ap);
        (void)fprintf(stderr, "\n");
        exit(2);
        /* NOTREACHED */
}