Fixed bug #853

Ludwig Nussel 2009-10-18 05:34:18 PDT src/joystick/linux/SDL_sysjoystick.c has some problems: - test_bit() might break with strict aliasing - test_bit() assumes array is Uint32 but its actually "unsigned long" on 64bit systems sizeof(long) != sizeof(Uint32). - the keybit array is too small - the arrays are unitialized so the number of detected buttons is quite random
libsdl-org · Oct 18, 2009 · 5873d77 · 5873d77
1 parent 61fb281
commit 5873d77
Showing 1 changed file with 8 additions and 7 deletions.
diff --git a/src/joystick/linux/SDL_sysjoystick.c b/src/joystick/linux/SDL_sysjoystick.c
@@ -374,13 +374,14 @@ static void LogicalSuffix(int logicalno, char* namebuf, int len)
 
 #if SDL_INPUT_LINUXEV
 #define test_bit(nr, addr) \
-	(((1UL << ((nr) & 31)) & (((const Uint32 *) addr)[(nr) >> 5])) != 0)
+	(((1UL << ((nr) % (sizeof(long) * 8))) & ((addr)[(nr) / (sizeof(long) * 8)])) != 0)
+#define NBITS(x) ((((x)-1)/(sizeof(long) * 8))+1)
 
 static int EV_IsJoystick(int fd)
 {
-	unsigned long evbit[40];
-	unsigned long keybit[40];
-	unsigned long absbit[40];
+	unsigned long evbit[NBITS(EV_MAX)] = { 0 };
+	unsigned long keybit[NBITS(KEY_MAX)] = { 0 };
+	unsigned long absbit[NBITS(ABS_MAX)] = { 0 };
 
 	if ( (ioctl(fd, EVIOCGBIT(0, sizeof(evbit)), evbit) < 0) ||
 	     (ioctl(fd, EVIOCGBIT(EV_KEY, sizeof(keybit)), keybit) < 0) ||
@@ -661,9 +662,9 @@ static SDL_bool JS_ConfigJoystick(SDL_Joystick *joystick, int fd)
 static SDL_bool EV_ConfigJoystick(SDL_Joystick *joystick, int fd)
 {
 	int i, t;
-	unsigned long keybit[40];
-	unsigned long absbit[40];
-	unsigned long relbit[40];
+	unsigned long keybit[NBITS(KEY_MAX)] = { 0 };
+	unsigned long absbit[NBITS(ABS_MAX)] = { 0 };
+	unsigned long relbit[NBITS(REL_MAX)] = { 0 };
 
 	/* See if this device uses the new unified event API */
 	if ( (ioctl(fd, EVIOCGBIT(EV_KEY, sizeof(keybit)), keybit) >= 0) &&