| 1 | /* |
| 2 | * Copyright (c) 1987 Regents of the University of California. |
| 3 | * All rights reserved. |
| 4 | * |
| 5 | * Redistribution and use in source and binary forms are permitted |
| 6 | * provided that the above copyright notice and this paragraph are |
| 7 | * duplicated in all such forms and that any documentation, |
| 8 | * advertising materials, and other materials related to such |
| 9 | * distribution and use acknowledge that the software was developed |
| 10 | * by the University of California, Berkeley. The name of the |
| 11 | * University may not be used to endorse or promote products derived |
| 12 | * from this software without specific prior written permission. |
| 13 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR |
| 14 | * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED |
| 15 | * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. |
| 16 | */ |
| 17 | |
| 18 | #ifndef lint |
| 19 | char copyright[] = |
| 20 | "@(#) Copyright (c) 1987 Regents of the University of California.\n\ |
| 21 | All rights reserved.\n"; |
| 22 | #endif /* not lint */ |
| 23 | |
| 24 | #ifndef lint |
| 25 | static char sccsid[] = "@(#)mesg.c 4.5 (Berkeley) %G%"; |
| 26 | #endif /* not lint */ |
| 27 | |
| 28 | /* |
| 29 | * mesg -- set current tty to accept or |
| 30 | * forbid write permission. |
| 31 | * |
| 32 | * mesg [y] [n] |
| 33 | * y allow messages |
| 34 | * n forbid messages |
| 35 | */ |
| 36 | |
| 37 | #include <sys/types.h> |
| 38 | #include <sys/stat.h> |
| 39 | #include <stdio.h> |
| 40 | |
| 41 | static char *tty; |
| 42 | |
| 43 | main(argc, argv) |
| 44 | int argc; |
| 45 | char **argv; |
| 46 | { |
| 47 | struct stat sbuf; |
| 48 | char *ttyname(); |
| 49 | |
| 50 | if (!(tty = ttyname(2))) { |
| 51 | fputs("mesg: not a device in /dev.\n", stderr); |
| 52 | exit(-1); |
| 53 | } |
| 54 | if (stat(tty, &sbuf) < 0) { |
| 55 | perror("mesg"); |
| 56 | exit(-1); |
| 57 | } |
| 58 | if (argc < 2) { |
| 59 | if (sbuf.st_mode & 020) { |
| 60 | fputs("is y\n", stderr); |
| 61 | exit(0); |
| 62 | } |
| 63 | fputs("is n\n", stderr); |
| 64 | exit(1); |
| 65 | } |
| 66 | #define OTHER_WRITE 020 |
| 67 | switch(*argv[1]) { |
| 68 | case 'y': |
| 69 | newmode(sbuf.st_mode | OTHER_WRITE); |
| 70 | exit(0); |
| 71 | case 'n': |
| 72 | newmode(sbuf.st_mode &~ OTHER_WRITE); |
| 73 | exit(1); |
| 74 | default: |
| 75 | fputs("usage: mesg [y] [n]\n", stderr); |
| 76 | exit(-1); |
| 77 | } |
| 78 | /*NOTREACHED*/ |
| 79 | } |
| 80 | |
| 81 | static |
| 82 | newmode(m) |
| 83 | u_short m; |
| 84 | { |
| 85 | if (chmod(tty, m) < 0) { |
| 86 | perror("mesg"); |
| 87 | exit(-1); |
| 88 | } |
| 89 | } |