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81 lines
2.2 KiB
C
81 lines
2.2 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* mesg implementation for busybox
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*
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* Copyright (c) 2002 Manuel Novoa III <mjn3@codepoet.org>
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*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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//config:config MESG
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//config: bool "mesg (1.2 kb)"
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//config: default y
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//config: help
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//config: Mesg controls access to your terminal by others. It is typically
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//config: used to allow or disallow other users to write to your terminal
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//config:
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//config:config FEATURE_MESG_ENABLE_ONLY_GROUP
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//config: bool "Enable writing to tty only by group, not by everybody"
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//config: default y
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//config: depends on MESG
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//config: help
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//config: Usually, ttys are owned by group "tty", and "write" tool is
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//config: setgid to this group. This way, "mesg y" only needs to enable
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//config: "write by owning group" bit in tty mode.
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//config:
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//config: If you set this option to N, "mesg y" will enable writing
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//config: by anybody at all. This is not recommended.
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//applet:IF_MESG(APPLET_NOFORK(mesg, mesg, BB_DIR_USR_BIN, BB_SUID_DROP, mesg))
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//kbuild:lib-$(CONFIG_MESG) += mesg.o
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//usage:#define mesg_trivial_usage
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//usage: "[y|n]"
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//usage:#define mesg_full_usage "\n\n"
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//usage: "Control write access to your terminal\n"
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//usage: " y Allow write access to your terminal\n"
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//usage: " n Disallow write access to your terminal"
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#include "libbb.h"
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#if ENABLE_FEATURE_MESG_ENABLE_ONLY_GROUP
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#define S_IWGRP_OR_S_IWOTH S_IWGRP
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#else
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#define S_IWGRP_OR_S_IWOTH (S_IWGRP | S_IWOTH)
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#endif
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int mesg_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int mesg_main(int argc UNUSED_PARAM, char **argv)
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{
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struct stat sb;
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mode_t m;
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char c = 0;
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argv++;
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if (argv[0]
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&& (argv[1] || ((c = argv[0][0]) != 'y' && c != 'n'))
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) {
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bb_show_usage();
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}
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/* We are a NOFORK applet.
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* (Not that it's very useful, but code is trivially NOFORK-safe).
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* Play nice. Do not leak anything.
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*/
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if (!isatty(STDIN_FILENO))
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bb_error_msg_and_die("not a tty");
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xfstat(STDIN_FILENO, &sb, "stdin");
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if (c == 0) {
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puts((sb.st_mode & (S_IWGRP|S_IWOTH)) ? "is y" : "is n");
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return EXIT_SUCCESS;
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}
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m = (c == 'y') ? sb.st_mode | S_IWGRP_OR_S_IWOTH
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: sb.st_mode & ~(S_IWGRP|S_IWOTH);
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if (fchmod(STDIN_FILENO, m) != 0)
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bb_perror_nomsg_and_die();
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return EXIT_SUCCESS;
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}
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