blob: 45c13b8e030e5fa3fe6446830ad6262b17fe8ac3
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * mesg implementation for busybox |
4 | * |
5 | * Copyright (c) 2002 Manuel Novoa III <mjn3@codepoet.org> |
6 | * |
7 | * Licensed under GPLv2 or later, see file LICENSE in this source tree. |
8 | */ |
9 | |
10 | //config:config MESG |
11 | //config: bool "mesg" |
12 | //config: default y |
13 | //config: help |
14 | //config: Mesg controls access to your terminal by others. It is typically |
15 | //config: used to allow or disallow other users to write to your terminal |
16 | //config: |
17 | //config:config FEATURE_MESG_ENABLE_ONLY_GROUP |
18 | //config: bool "Enable writing to tty only by group, not by everybody" |
19 | //config: default y |
20 | //config: depends on MESG |
21 | //config: help |
22 | //config: Usually, ttys are owned by group "tty", and "write" tool is |
23 | //config: setgid to this group. This way, "mesg y" only needs to enable |
24 | //config: "write by owning group" bit in tty mode. |
25 | //config: |
26 | //config: If you set this option to N, "mesg y" will enable writing |
27 | //config: by anybody at all. This is not recommended. |
28 | |
29 | //applet:IF_MESG(APPLET(mesg, BB_DIR_USR_BIN, BB_SUID_DROP)) |
30 | |
31 | //kbuild:lib-$(CONFIG_MESG) += mesg.o |
32 | |
33 | //usage:#define mesg_trivial_usage |
34 | //usage: "[y|n]" |
35 | //usage:#define mesg_full_usage "\n\n" |
36 | //usage: "Control write access to your terminal\n" |
37 | //usage: " y Allow write access to your terminal\n" |
38 | //usage: " n Disallow write access to your terminal" |
39 | |
40 | #include "libbb.h" |
41 | |
42 | #if ENABLE_FEATURE_MESG_ENABLE_ONLY_GROUP |
43 | #define S_IWGRP_OR_S_IWOTH S_IWGRP |
44 | #else |
45 | #define S_IWGRP_OR_S_IWOTH (S_IWGRP | S_IWOTH) |
46 | #endif |
47 | |
48 | int mesg_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
49 | int mesg_main(int argc UNUSED_PARAM, char **argv) |
50 | { |
51 | struct stat sb; |
52 | mode_t m; |
53 | char c = 0; |
54 | |
55 | argv++; |
56 | |
57 | if (argv[0] |
58 | && (argv[1] || ((c = argv[0][0]) != 'y' && c != 'n')) |
59 | ) { |
60 | bb_show_usage(); |
61 | } |
62 | |
63 | if (!isatty(STDIN_FILENO)) |
64 | bb_error_msg_and_die("not a tty"); |
65 | |
66 | xfstat(STDIN_FILENO, &sb, "stderr"); |
67 | if (c == 0) { |
68 | puts((sb.st_mode & (S_IWGRP|S_IWOTH)) ? "is y" : "is n"); |
69 | return EXIT_SUCCESS; |
70 | } |
71 | m = (c == 'y') ? sb.st_mode | S_IWGRP_OR_S_IWOTH |
72 | : sb.st_mode & ~(S_IWGRP|S_IWOTH); |
73 | if (fchmod(STDIN_FILENO, m) != 0) |
74 | bb_perror_nomsg_and_die(); |
75 | return EXIT_SUCCESS; |
76 | } |
77 |