From 724d24d990868e617ea897352064909cc26e1965 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <icculus@icculus.org>
Date: Sun, 31 Aug 2014 11:21:10 -0400
Subject: [PATCH] Mac: Don't add the same joystick twice if IOKit reports a
 duplicate device.

Fixes Bugzilla #2704.
---
 src/joystick/darwin/SDL_sysjoystick.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/joystick/darwin/SDL_sysjoystick.c b/src/joystick/darwin/SDL_sysjoystick.c
index f0bd5b8d1..0518cc75b 100644
--- a/src/joystick/darwin/SDL_sysjoystick.c
+++ b/src/joystick/darwin/SDL_sysjoystick.c
@@ -364,15 +364,33 @@ GetDeviceInfo(IOHIDDeviceRef hidDevice, recDevice *pDevice)
     return SDL_TRUE;
 }
 
+static SDL_bool
+JoystickAlreadyKnown(IOHIDDeviceRef ioHIDDeviceObject)
+{
+    recDevice *i;
+    for (i = gpDeviceList; i != NULL; i = i->pNext) {
+        if (i->deviceRef == ioHIDDeviceObject) {
+            return SDL_TRUE;
+        }
+    }
+    return SDL_FALSE;
+}
+
 
 static void
 JoystickDeviceWasAddedCallback(void *ctx, IOReturn res, void *sender, IOHIDDeviceRef ioHIDDeviceObject)
 {
+    recDevice *device;
+
     if (res != kIOReturnSuccess) {
         return;
     }
 
-    recDevice *device = (recDevice *) SDL_calloc(1, sizeof(recDevice));
+    if (JoystickAlreadyKnown(ioHIDDeviceObject)) {
+        return;  /* IOKit sent us a duplicate. */
+    }
+
+    device = (recDevice *) SDL_calloc(1, sizeof(recDevice));
 
     if (!device) {
         SDL_OutOfMemory();