Add isAidlNativeHandleEmpty to libaidlcommonsupport

Bug: 251042358
Test: libaidlcommonsupport_test
Signed-off-by: Roman Kiryanov <rkir@google.com>
Change-Id: I96dc2a39d60f955b8a686adcb7446e1c54747a35
diff --git a/common/support/NativeHandle.cpp b/common/support/NativeHandle.cpp
index 321d7a8..126ef2e 100644
--- a/common/support/NativeHandle.cpp
+++ b/common/support/NativeHandle.cpp
@@ -22,6 +22,13 @@
 
 using aidl::android::hardware::common::NativeHandle;
 
+/**
+ * Checks if a NativeHandle is null
+ */
+bool isAidlNativeHandleEmpty(const NativeHandle& handle) {
+    return handle.fds.empty() && handle.ints.empty();
+}
+
 static native_handle_t* fromAidl(const NativeHandle& handle, bool doDup) {
     native_handle_t* to = native_handle_create(handle.fds.size(), handle.ints.size());
     if (!to) return nullptr;
diff --git a/common/support/include/aidlcommonsupport/NativeHandle.h b/common/support/include/aidlcommonsupport/NativeHandle.h
index 10eecba..b5ea1dd 100644
--- a/common/support/include/aidlcommonsupport/NativeHandle.h
+++ b/common/support/include/aidlcommonsupport/NativeHandle.h
@@ -22,6 +22,11 @@
 namespace android {
 
 /**
+ * Checks if a NativeHandle is empty.
+ */
+bool isAidlNativeHandleEmpty(const aidl::android::hardware::common::NativeHandle& handle);
+
+/**
  * Creates a libcutils native handle from an AIDL native handle, but it does not
  * dup internally, so it will contain the same FDs as the handle itself. The
  * result should be deleted with native_handle_delete.
diff --git a/common/support/test.cpp b/common/support/test.cpp
index 2359277..9b79581 100644
--- a/common/support/test.cpp
+++ b/common/support/test.cpp
@@ -62,6 +62,7 @@
 
 TEST(ConvertNativeHandle, MakeFromAidlEmpty) {
     NativeHandle handle;
+    EXPECT_TRUE(isAidlNativeHandleEmpty(handle));
     native_handle_t* to = makeFromAidl(handle);
     checkEq(handle, to, false /*exceptFds*/);
     // no native_handle_close b/c fds are owned by NativeHandle
@@ -70,6 +71,7 @@
 
 TEST(ConvertNativeHandle, MakeFromAidl) {
     NativeHandle handle = makeTestAidlHandle();
+    EXPECT_FALSE(isAidlNativeHandleEmpty(handle));
     native_handle_t* to = makeFromAidl(handle);
     checkEq(handle, to, false /*exceptFds*/);
     // no native_handle_close b/c fds are owned by NativeHandle
@@ -106,6 +108,7 @@
 TEST(ConvertNativeHandle, MakeToAidlEmpty) {
     native_handle_t* handle = native_handle_create(0, 0);
     NativeHandle to = makeToAidl(handle);
+    EXPECT_TRUE(isAidlNativeHandleEmpty(to));
     checkEq(to, handle, false /*exceptFds*/);
     // no native_handle_close b/c fds are owned by NativeHandle now
     EXPECT_EQ(0, native_handle_delete(handle));
@@ -114,6 +117,7 @@
 TEST(ConvertNativeHandle, MakeToAidl) {
     native_handle_t* handle = makeTestLibcutilsHandle();
     NativeHandle to = makeToAidl(handle);
+    EXPECT_FALSE(isAidlNativeHandleEmpty(to));
     checkEq(to, handle, false /*exceptFds*/);
     // no native_handle_close b/c fds are owned by NativeHandle now
     EXPECT_EQ(0, native_handle_delete(handle));
@@ -122,6 +126,7 @@
 TEST(ConvertNativeHandle, DupToAidlEmpty) {
     native_handle_t* handle = native_handle_create(0, 0);
     NativeHandle to = dupToAidl(handle);
+    EXPECT_TRUE(isAidlNativeHandleEmpty(to));
     checkEq(to, handle, true /*exceptFds*/);
     EXPECT_EQ(0, native_handle_close(handle));
     EXPECT_EQ(0, native_handle_delete(handle));
@@ -130,6 +135,7 @@
 TEST(ConvertNativeHandle, DupToAidl) {
     native_handle_t* handle = makeTestLibcutilsHandle();
     NativeHandle to = dupToAidl(handle);
+    EXPECT_FALSE(isAidlNativeHandleEmpty(to));
     checkEq(to, handle, true /*exceptFds*/);
     EXPECT_EQ(0, native_handle_close(handle));
     EXPECT_EQ(0, native_handle_delete(handle));