libbinder: size checks for Parcel+IBinder

(the ones for Parcel are just improved)

These types are used in prebuilts, so it's useful to know the size
changes w/ having to wait for DOA devices.

Bug: 166282674
Test: build only (these are compile-time checks)
Change-Id: Ib6deda78a3f2bf537b3163ae7ea5a703b1c8e289

2 files changed, 15 insertions, 1 deletions

diff --git a/libs/binder/Binder.cpp b/libs/binder/Binder.cpp
index d964d255fe..d5bdd1c803 100644
--- a/libs/binder/Binder.cpp
+++ b/libs/binder/Binder.cpp
@@ -29,6 +29,16 @@
 
 namespace android {
 
+// Service implementations inherit from BBinder and IBinder, and this is frozen
+// in prebuilts.
+#ifdef __LP64__
+static_assert(sizeof(IBinder) == 24);
+static_assert(sizeof(BBinder) == 40);
+#else
+static_assert(sizeof(IBinder) == 12);
+static_assert(sizeof(BBinder) == 20);
+#endif
+
 // ---------------------------------------------------------------------------
 
 IBinder::IBinder()
diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index 98ca829031..39d6a2ec4f 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -78,7 +78,11 @@ static size_t pad_size(size_t s) {
 namespace android {
 
 // many things compile this into prebuilts on the stack
-static_assert(sizeof(Parcel) == 60 || sizeof(Parcel) == 120);
+#ifdef __LP64__
+static_assert(sizeof(Parcel) == 120);
+#else
+static_assert(sizeof(Parcel) == 60);
+#endif
 
 static std::atomic<size_t> gParcelGlobalAllocCount;
 static std::atomic<size_t> gParcelGlobalAllocSize;