Re-add backtrace note about unreadable elf.

When moving to the proto-ized tombstones, the note about unreadable
elf files in a backtrace got lost. This re-adds it and adds a test
to verify that the note properly shows up.

Bug: 185428454

Test: Ran unit tests.
Change-Id: I1150cc737772e1b79fd73ec5c782caadc4629421

1 files changed, 21 insertions, 0 deletions

diff --git a/debuggerd/crash_test.cpp b/debuggerd/crash_test.cpp
new file mode 100644
index 000000000..c15145f61
--- /dev/null
+++ b/debuggerd/crash_test.cpp
@@ -0,0 +1,21 @@
+/*
+ * Copyright 2021, 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.
+ */
+
+#include <stdint.h>
+
+extern "C" void crash() {
+  *reinterpret_cast<volatile char*>(0xdead) = '1';
+}