| /* vi: set sw=4 ts=4: */ |
| /* |
| * mesg implementation for busybox |
| * |
| * Copyright (c) 2002 Manuel Novoa III <mjn3@codepoet.org> |
| * |
| * Licensed under GPLv2 or later, see file LICENSE in this source tree. |
| */ |
| |
| //config:config MESG |
| //config: bool "mesg" |
| //config: default y |
| //config: help |
| //config: Mesg controls access to your terminal by others. It is typically |
| //config: used to allow or disallow other users to write to your terminal |
| //config: |
| //config:config FEATURE_MESG_ENABLE_ONLY_GROUP |
| //config: bool "Enable writing to tty only by group, not by everybody" |
| //config: default y |
| //config: depends on MESG |
| //config: help |
| //config: Usually, ttys are owned by group "tty", and "write" tool is |
| //config: setgid to this group. This way, "mesg y" only needs to enable |
| //config: "write by owning group" bit in tty mode. |
| //config: |
| //config: If you set this option to N, "mesg y" will enable writing |
| //config: by anybody at all. This is not recommended. |
| |
| //applet:IF_MESG(APPLET(mesg, BB_DIR_USR_BIN, BB_SUID_DROP)) |
| |
| //kbuild:lib-$(CONFIG_MESG) += mesg.o |
| |
| //usage:#define mesg_trivial_usage |
| //usage: "[y|n]" |
| //usage:#define mesg_full_usage "\n\n" |
| //usage: "Control write access to your terminal\n" |
| //usage: " y Allow write access to your terminal\n" |
| //usage: " n Disallow write access to your terminal" |
| |
| #include "libbb.h" |
| |
| #if ENABLE_FEATURE_MESG_ENABLE_ONLY_GROUP |
| #define S_IWGRP_OR_S_IWOTH S_IWGRP |
| #else |
| #define S_IWGRP_OR_S_IWOTH (S_IWGRP | S_IWOTH) |
| #endif |
| |
| int mesg_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
| int mesg_main(int argc UNUSED_PARAM, char **argv) |
| { |
| struct stat sb; |
| mode_t m; |
| char c = 0; |
| |
| argv++; |
| |
| if (argv[0] |
| && (argv[1] || ((c = argv[0][0]) != 'y' && c != 'n')) |
| ) { |
| bb_show_usage(); |
| } |
| |
| if (!isatty(STDIN_FILENO)) |
| bb_error_msg_and_die("not a tty"); |
| |
| xfstat(STDIN_FILENO, &sb, "stderr"); |
| if (c == 0) { |
| puts((sb.st_mode & (S_IWGRP|S_IWOTH)) ? "is y" : "is n"); |
| return EXIT_SUCCESS; |
| } |
| m = (c == 'y') ? sb.st_mode | S_IWGRP_OR_S_IWOTH |
| : sb.st_mode & ~(S_IWGRP|S_IWOTH); |
| if (fchmod(STDIN_FILENO, m) != 0) |
| bb_perror_nomsg_and_die(); |
| return EXIT_SUCCESS; |
| } |