MappedFile and FileMap should support zero-length mappings.

Bug: http://b/119818070 "app crashes when reading asset of zero length"
Test: ran tests
Change-Id: Idd2ad6f6e72c8e445aff78a460fac96dea41c950

2 files changed, 35 insertions, 0 deletions

diff --git a/libutils/tests/Android.bp b/libutils/tests/Android.bp
index 1390552fa..62f5acb4e 100644
--- a/libutils/tests/Android.bp
+++ b/libutils/tests/Android.bp
@@ -22,6 +22,7 @@ cc_test {
 
     srcs: [
         "BitSet_test.cpp",
+        "FileMap_test.cpp",
         "LruCache_test.cpp",
         "Mutex_test.cpp",
         "Singleton_test.cpp",
diff --git a/libutils/tests/FileMap_test.cpp b/libutils/tests/FileMap_test.cpp
new file mode 100644
index 000000000..576d89bbe
--- /dev/null
+++ b/libutils/tests/FileMap_test.cpp
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2019 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 "utils/FileMap.h"
+
+#include <gtest/gtest.h>
+
+#include "android-base/file.h"
+
+TEST(FileMap, zero_length_mapping) {
+    // http://b/119818070 "app crashes when reading asset of zero length".
+    // mmap fails with EINVAL for a zero length region.
+    TemporaryFile tf;
+    ASSERT_TRUE(tf.fd != -1);
+
+    android::FileMap m;
+    ASSERT_TRUE(m.create("test", tf.fd, 4096, 0, true));
+    ASSERT_STREQ("test", m.getFileName());
+    ASSERT_EQ(0u, m.getDataLength());
+    ASSERT_EQ(4096, m.getDataOffset());
+}