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Prevent keystrokes from leaking through to the console when using evdev.

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This uses the same method Weston and X use. Sadly, to be fully effective when
launching remotely, this needs root permissions.
This commit is contained in:
Gabriel Jacobo 2013-10-13 17:15:43 -03:00
parent 146a3bc324
commit dd7e8526a2
3 changed files with 103 additions and 1 deletions
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97
src/input/evdev/SDL_evdev.c
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@ -45,6 +45,18 @@ static _THIS = NULL;
#include <linux/keyboard.h>
#endif
/* We need this to prevent keystrokes from appear in the console */
#ifndef KDSKBMUTE
#define KDSKBMUTE 0x4B51
#endif
#ifndef KDSKBMODE
#define KDSKBMODE 0x4B45
#endif
#ifndef K_OFF
#define K_OFF 0x04
#endif
#include "SDL.h"
#include "SDL_assert.h"
#include "SDL_endian.h"
@ -370,6 +382,72 @@ static int SDL_EVDEV_get_console_fd(void)
return -1;
}
/* Prevent keystrokes from reaching the tty */
static int SDL_EVDEV_mute_keyboard(int tty, int *kb_mode)
{
char arg;
*kb_mode = 0; /* FIXME: Is this a sane default in case KDGKBMODE fails? */
if (!IS_CONSOLE(tty)) {
return SDL_SetError("Tried to mute an invalid tty");
}
ioctl(tty, KDGKBMODE, kb_mode); /* It's not fatal if this fails */
if (ioctl(tty, KDSKBMUTE, 1) && ioctl(tty, KDSKBMODE, K_OFF)) {
return SDL_SetError("EVDEV: Failed muting keyboard");
}
return 0;
}
/* Restore the keyboard mode for given tty */
static void SDL_EVDEV_unmute_keyboard(int tty, int kb_mode)
{
if (ioctl(tty, KDSKBMUTE, 0) && ioctl(tty, KDSKBMODE, kb_mode)) {
SDL_Log("EVDEV: Failed restoring keyboard mode");
}
}
/* Read /sys/class/tty/tty0/active and open the tty */
static int SDL_EVDEV_get_active_tty()
{
int fd, len;
char ttyname[NAME_MAX + 1];
char ttypath[PATH_MAX+1] = "/dev/";
char arg;
fd = open("/sys/class/tty/tty0/active", O_RDONLY);
if (fd < 0) {
return SDL_SetError("Could not determine which tty is active");
}
len = read(fd, ttyname, NAME_MAX);
close(fd);
if (len <= 0) {
return SDL_SetError("Could not read which tty is active");
}
if (ttyname[len-1] == '\n') {
ttyname[len-1] = '\0';
}
else {
ttyname[len] = '\0';
}
SDL_strlcat(ttypath, ttyname, PATH_MAX);
fd = open(ttypath, O_RDWR | O_NOCTTY);
if (fd < 0) {
return SDL_SetError("Could not open tty: %s", ttypath);
}
if (!IS_CONSOLE(fd)) {
close(fd);
return SDL_SetError("Invalid tty obtained: %s", ttypath);
}
return fd;
}
int
SDL_EVDEV_Init(void)
{
@ -403,6 +481,19 @@ SDL_EVDEV_Init(void)
/* We need a physical terminal (not PTS) to be able to translate key code to symbols via the kernel tables */
_this->console_fd = SDL_EVDEV_get_console_fd();
/* Mute the keyboard so keystrokes only generate evdev events and do not leak through to the console */
_this->tty = STDIN_FILENO;
if (SDL_EVDEV_mute_keyboard(_this->tty, &_this->kb_mode) < 0) {
/* stdin is not a tty, probably we were launched remotely, so we try to disable the active tty */
_this->tty = SDL_EVDEV_get_active_tty();
if (_this->tty >= 0) {
if (SDL_EVDEV_mute_keyboard(_this->tty, &_this->kb_mode) < 0) {
close(_this->tty);
_this->tty = -1;
}
}
}
}
_this->ref_count += 1;
@ -429,6 +520,12 @@ SDL_EVDEV_Quit(void)
if (_this->console_fd >= 0) {
close(_this->console_fd);
}
if (_this->tty >= 0) {
SDL_EVDEV_unmute_keyboard(_this->tty, _this->kb_mode);
close(_this->tty);
}
/* Remove existing devices */
while(_this->first != NULL) {
SDL_EVDEV_device_removed(_this->first->path);