support lib for libcutils<->NDK AIDL handle

The native_handle API is notoriously tricky to work with, and this is
expected to be very common. So, adding a small helper library.

Fixes: 175432703
Test: atest libaidlcommonsupport_test
Change-Id: I4a00d2b14fefe6c979ee656e353e117661a1a483
diff --git a/common/support/test.cpp b/common/support/test.cpp
new file mode 100644
index 0000000..2359277
--- /dev/null
+++ b/common/support/test.cpp
@@ -0,0 +1,138 @@
+/*
+ * Copyright (C) 2020 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 <aidlcommonsupport/NativeHandle.h>
+#include <gtest/gtest.h>
+
+namespace android {
+
+using aidl::android::hardware::common::NativeHandle;
+using ndk::ScopedFileDescriptor;
+
+static void checkEq(const NativeHandle& aidl, native_handle_t* libcutils, bool exceptFds) {
+    ASSERT_NE(libcutils, nullptr);
+    ASSERT_EQ(libcutils->numFds, aidl.fds.size());
+
+    for (size_t i = 0; i < libcutils->numFds; i++) {
+        int afd = aidl.fds.at(i).get();
+        int lfd = libcutils->data[i];
+
+        EXPECT_GE(afd, 0) << "Invalid fd at index " << i;
+        EXPECT_GE(lfd, 0) << "Invalid fd at index " << i;
+
+        if (exceptFds) {
+            EXPECT_NE(afd, lfd) << "Index matched at " << i << " but should be dup'd fd";
+        } else {
+            EXPECT_EQ(afd, lfd) << "Index mismatched at " << i << " but should be same fd";
+        }
+    }
+
+    ASSERT_EQ(libcutils->numInts, aidl.ints.size());
+
+    for (size_t i = 0; i < libcutils->numInts; i++) {
+        int afd = aidl.ints.at(i);
+        int lfd = libcutils->data[libcutils->numFds + i];
+
+        EXPECT_EQ(afd, lfd) << "Index mismatch at " << i;
+    }
+}
+
+static NativeHandle makeTestAidlHandle() {
+    NativeHandle handle = {
+            .fds = std::vector<ScopedFileDescriptor>(2),
+            .ints = {1, 2, 3, 4},
+    };
+    handle.fds[0].set(dup(0));
+    handle.fds[1].set(dup(0));
+    return handle;
+}
+
+TEST(ConvertNativeHandle, MakeFromAidlEmpty) {
+    NativeHandle handle;
+    native_handle_t* to = makeFromAidl(handle);
+    checkEq(handle, to, false /*exceptFds*/);
+    // no native_handle_close b/c fds are owned by NativeHandle
+    EXPECT_EQ(0, native_handle_delete(to));
+}
+
+TEST(ConvertNativeHandle, MakeFromAidl) {
+    NativeHandle handle = makeTestAidlHandle();
+    native_handle_t* to = makeFromAidl(handle);
+    checkEq(handle, to, false /*exceptFds*/);
+    // no native_handle_close b/c fds are owned by NativeHandle
+    EXPECT_EQ(0, native_handle_delete(to));
+}
+
+TEST(ConvertNativeHandle, DupFromAidlEmpty) {
+    NativeHandle handle;
+    native_handle_t* to = dupFromAidl(handle);
+    checkEq(handle, to, true /*exceptFds*/);
+    EXPECT_EQ(0, native_handle_close(to));
+    EXPECT_EQ(0, native_handle_delete(to));
+}
+
+TEST(ConvertNativeHandle, DupFromAidl) {
+    NativeHandle handle = makeTestAidlHandle();
+    native_handle_t* to = dupFromAidl(handle);
+    checkEq(handle, to, true /*exceptFds*/);
+    EXPECT_EQ(0, native_handle_close(to));
+    EXPECT_EQ(0, native_handle_delete(to));
+}
+
+static native_handle_t* makeTestLibcutilsHandle() {
+    native_handle_t* handle = native_handle_create(2, 4);
+    handle->data[0] = dup(0);
+    handle->data[1] = dup(0);
+    handle->data[2] = 1;
+    handle->data[3] = 2;
+    handle->data[4] = 3;
+    handle->data[5] = 4;
+    return handle;
+}
+
+TEST(ConvertNativeHandle, MakeToAidlEmpty) {
+    native_handle_t* handle = native_handle_create(0, 0);
+    NativeHandle to = makeToAidl(handle);
+    checkEq(to, handle, false /*exceptFds*/);
+    // no native_handle_close b/c fds are owned by NativeHandle now
+    EXPECT_EQ(0, native_handle_delete(handle));
+}
+
+TEST(ConvertNativeHandle, MakeToAidl) {
+    native_handle_t* handle = makeTestLibcutilsHandle();
+    NativeHandle to = makeToAidl(handle);
+    checkEq(to, handle, false /*exceptFds*/);
+    // no native_handle_close b/c fds are owned by NativeHandle now
+    EXPECT_EQ(0, native_handle_delete(handle));
+}
+
+TEST(ConvertNativeHandle, DupToAidlEmpty) {
+    native_handle_t* handle = native_handle_create(0, 0);
+    NativeHandle to = dupToAidl(handle);
+    checkEq(to, handle, true /*exceptFds*/);
+    EXPECT_EQ(0, native_handle_close(handle));
+    EXPECT_EQ(0, native_handle_delete(handle));
+}
+
+TEST(ConvertNativeHandle, DupToAidl) {
+    native_handle_t* handle = makeTestLibcutilsHandle();
+    NativeHandle to = dupToAidl(handle);
+    checkEq(to, handle, true /*exceptFds*/);
+    EXPECT_EQ(0, native_handle_close(handle));
+    EXPECT_EQ(0, native_handle_delete(handle));
+}
+
+}  // namespace android