source: branches/3.2/mindi-busybox/init/mesg.c @ 3232

Last change on this file since 3232 was 3232, checked in by bruno, 6 years ago
  • Update mindi-busybox to 1.21.1
File size: 2.1 KB
Line 
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
48int mesg_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
49int 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}
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