Make use of sigchainlib for signal chaining for implicit checks

This adds a preload library that overrides sigaction and sigprocmask
to implement signal chaining.  Signal chaining allows us to chain
any signal so that the ART runtime receives it before any signal
handler registered in native code by an application.  If the
ART signal handler doesn't want it, it will pass it on to the
user's handler.

ART uses signals for null pointer checks, stack overflow checks and
suspend points.

Also adds an OAT test to test this in isolation.

Change-Id: I9545f9f7343774c091410eb810504d9855fd399f
diff --git a/test/SignalTest/SignalTest.java b/test/SignalTest/SignalTest.java
new file mode 100644
index 0000000..7f15aea
--- /dev/null
+++ b/test/SignalTest/SignalTest.java
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+class SignalTest {
+    private static native void initSignalTest();
+    private static native void terminateSignalTest();
+    private static native int testSignal();
+
+    private static void stackOverflow() {
+       stackOverflow();
+    }
+
+    public static void main(String[] args) {
+        System.loadLibrary("arttest");
+
+        System.out.println("init signal test");
+        initSignalTest();
+        try {
+            Object o = null;
+            int hash = o.hashCode();
+
+            // Should never get here.
+            System.out.println("hash: " + hash);
+            throw new AssertionError();
+        } catch (NullPointerException e) {
+            System.out.println("Caught NullPointerException");
+        }
+        try {
+            stackOverflow();
+
+            // Should never get here.
+            throw new AssertionError();
+        } catch (StackOverflowError e) {
+            System.out.println("Caught StackOverflowError");
+        }
+
+        // Test that a signal in native code works.  This will return
+        // the value 1234 if the signal is caught.
+        int x = testSignal();
+        if (x != 1234) {
+            throw new AssertionError();
+        }
+
+        terminateSignalTest();
+        System.out.println("Signal test OK");
+    }
+}