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mesg: make group/all writability configurable

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2011-03-22 06:54:36 +01:00
parent b0e8ced358
commit beea5a70c3
1 changed files with 35 additions and 25 deletions
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60
init/mesg.c
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@ -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();
}
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;
}
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;
}