*
* Copyright (c) 2002 Manuel Novoa III <mjn3@codepoet.org>
*
- * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
+ * 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"
-#ifdef USE_TTY_GROUP
-#define S_IWGRP_OR_S_IWOTH S_IWGRP
+#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)
+#define S_IWGRP_OR_S_IWOTH (S_IWGRP | S_IWOTH)
#endif
-int mesg_main(int argc, char **argv);
-int mesg_main(int argc, char **argv)
+int mesg_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int mesg_main(int argc UNUSED_PARAM, char **argv)
{
struct stat sb;
- const char *tty;
+ mode_t m;
char c = 0;
- if (--argc == 0
- || (argc == 1 && ((c = **++argv) == 'y' || c == 'n'))
+ argv++;
+
+ if (argv[0]
+ && (argv[1] || ((c = argv[0][0]) != 'y' && c != 'n'))
) {
- tty = ttyname(STDERR_FILENO);
- if (tty == NULL) {
- tty = "ttyname";
- } else if (stat(tty, &sb) == 0) {
- mode_t m;
- if (argc == 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 (chmod(tty, m) == 0) {
- return EXIT_SUCCESS;
- }
- }
- bb_perror_msg_and_die("%s", tty);
+ 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;
}
- bb_show_usage();
+ 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;
}