/* * Copyright (c) 1987 Regents of the University of California. * All rights reserved. * * Redistribution and use in source and binary forms are permitted * provided that: (1) source distributions retain this entire copyright * notice and comment, and (2) distributions including binaries display * the following acknowledgement: ``This product includes software * developed by the University of California, Berkeley and its contributors'' * in the documentation or other materials provided with the distribution * and in all advertising materials mentioning features or use of this * software. Neither the name of the University nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. */ #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 4.6 (Berkeley) 6/1/90"; #endif /* not lint */ /* * mesg -- set current tty to accept or * forbid write permission. * * mesg [y] [n] * y allow messages * n forbid messages */ #include <sys/types.h> #include <sys/stat.h> #include <stdio.h> static char *tty; main(argc, argv) int argc; char **argv; { struct stat sbuf; char *ttyname(); if (!(tty = ttyname(2))) { fputs("mesg: not a device in /dev.\n", stderr); exit(-1); } if (stat(tty, &sbuf) < 0) { perror("mesg"); exit(-1); } if (argc < 2) { if (sbuf.st_mode & 020) { fputs("is y\n", stderr); exit(0); } fputs("is n\n", stderr); exit(1); } #define OTHER_WRITE 020 switch(*argv[1]) { case 'y': newmode(sbuf.st_mode | OTHER_WRITE); exit(0); case 'n': newmode(sbuf.st_mode &~ OTHER_WRITE); exit(1); default: fputs("usage: mesg [y] [n]\n", stderr); exit(-1); } /*NOTREACHED*/ } static newmode(m) u_short m; { if (chmod(tty, m) < 0) { perror("mesg"); exit(-1); } }