From 0eab8214986faf6e5ba1982b8b01c4f06d61b3c4 Mon Sep 17 00:00:00 2001
From: Mathias Agopian <mathias@google.com>
Date: Mon, 7 Mar 2011 17:49:54 -0800
Subject: [PATCH] fix [4026375] SensorManager quaternion functions can call
 sqrt with a negative number

Just make sure to clamp the argument to zero.

Bug: 4026375
Change-Id: I00c5f6c83659a290d5e1e191a1c8d25ec06834c2
---
 core/java/android/hardware/SensorManager.java | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/core/java/android/hardware/SensorManager.java b/core/java/android/hardware/SensorManager.java
index dd4096bf05e3a..2111ccedbc394 100644
--- a/core/java/android/hardware/SensorManager.java
+++ b/core/java/android/hardware/SensorManager.java
@@ -2051,8 +2051,8 @@ public class SensorManager
         if (rv.length == 4) {
             Q[0] = rv[3];
         } else {
-            //In this case, the w component of the quaternion is known to be a positive number
-            Q[0] = (float)Math.sqrt(1 - rv[0]*rv[0] - rv[1]*rv[1] - rv[2]*rv[2]);
+            Q[0] = 1 - rv[0]*rv[0] - rv[1]*rv[1] - rv[2]*rv[2];
+            Q[0] = (Q[0] > 0) ? (float)Math.sqrt(Q[0]) : 0;
         }
         Q[1] = rv[0];
         Q[2] = rv[1];