1 files changed, 76 insertions, 0 deletions
diff --git a/util-linux/mesg.c b/util-linux/mesg.c
new file mode 100644
index 000000000..45c13b8e0
--- /dev/null
+++ b/util-linux/mesg.c
@@ -0,0 +1,76 @@
+/* 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;
+}