/* 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 (1.2 kb)" //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_NOFORK(mesg, mesg, BB_DIR_USR_BIN, BB_SUID_DROP, mesg)) //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(); } /* We are a NOFORK applet. * (Not that it's very useful, but code is trivially NOFORK-safe). * Play nice. Do not leak anything. */ if (!isatty(STDIN_FILENO)) bb_error_msg_and_die("not a tty"); xfstat(STDIN_FILENO, &sb, "stdin"); 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; }