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authorDenys Vlasenko <vda.linux@googlemail.com>2011-03-22 05:54:36 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2011-03-22 05:54:36 (GMT)
commitbeea5a70c34bdcf2b02c37e6f56d2efcbd90fedb (patch)
tree45947cc3220ee84edcfd9e9dabf0a5cec7e81241
parentb0e8ced3589c601ad5c15e74d6f82b1928e1eb8f (diff)
downloadbusybox-beea5a70c34bdcf2b02c37e6f56d2efcbd90fedb.tar.gz
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mesg: make group/all writability configurable
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--init/mesg.c60
1 files changed, 35 insertions, 25 deletions
diff --git a/init/mesg.c b/init/mesg.c
index 676ca2e..8489e62 100644
--- a/init/mesg.c
+++ b/init/mesg.c
@@ -7,16 +7,28 @@
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
-//applet:IF_MESG(APPLET(mesg, BB_DIR_USR_BIN, BB_SUID_DROP))
-
-//kbuild:lib-$(CONFIG_MESG) += mesg.o
-
//config:config MESG
//config: bool "mesg"
//config: default y
//config: help
//config: Mesg controls access to your terminal by others. It is typically
//config: used to allow or disallow other users to write to your terminal
+//config:
+//config:config FEATURE_MESG_ENABLE_ONLY_GROUP
+//config: bool "Enable writing to tty only by group, not by everybody"
+//config: default y
+//config: depends on MESG
+//config: help
+//config: Usually, ttys are owned by group "tty", and "write" tool is
+//config: setgid to this group. This way, "mesg y" only needs to enable
+//config: "write by owning group" bit in tty mode.
+//config:
+//config: If you set this option to N, "mesg y" will enable writing
+//config: by anybody at all. This is not recommended.
+
+//applet:IF_MESG(APPLET(mesg, BB_DIR_USR_BIN, BB_SUID_DROP))
+
+//kbuild:lib-$(CONFIG_MESG) += mesg.o
//usage:#define mesg_trivial_usage
//usage: "[y|n]"
@@ -27,7 +39,7 @@
#include "libbb.h"
-#ifdef USE_TTY_GROUP
+#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)
@@ -37,30 +49,28 @@ 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;
argv++;
- if (!argv[0]
- || (!argv[1] && ((c = argv[0][0]) == 'y' || c == 'n'))
+ if (argv[0]
+ && (argv[1] || ((c = argv[0][0]) != 'y' && c != 'n'))
) {
- tty = xmalloc_ttyname(STDERR_FILENO);
- if (tty == NULL) {
- tty = "ttyname";
- } else if (stat(tty, &sb) == 0) {
- mode_t m;
- 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 (chmod(tty, m) == 0) {
- return EXIT_SUCCESS;
- }
- }
- bb_simple_perror_msg_and_die(tty);
+ bb_show_usage();
+ }
+
+ if (!isatty(STDERR_FILENO))
+ bb_error_msg_and_die("not a tty");
+
+ xfstat(STDERR_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(STDERR_FILENO, m) != 0)
+ bb_perror_nomsg_and_die();
+ return EXIT_SUCCESS;
}