libbinder_ndk: Add stability downgrade

This can be used to allow registering a service with a VINTF interface
without requiring a manifest declaration.

This is useful for test services or in the case of a system proxy
service that implements the same interface as the vintf service.

Bug: 183154648
Bug: 177664629
Test: atest binderStabilityTest
Change-Id: Ibd8dad46945a339b77dca70484082fda06220ee3

1 files changed, 14 insertions, 2 deletions

diff --git a/libs/binder/Stability.cpp b/libs/binder/Stability.cpp
index 06830c027b..709cf67127 100644
--- a/libs/binder/Stability.cpp
+++ b/libs/binder/Stability.cpp
@@ -38,18 +38,30 @@ Stability::Category Stability::Category::currentFromLevel(Level level) {
     };
 }
 
-void Stability::forceDowngradeCompilationUnit(const sp<IBinder>& binder) {
+void Stability::forceDowngradeToStability(const sp<IBinder>& binder, Level level) {
     // Downgrading a remote binder would require also copying the version from
     // the binder sent here. In practice though, we don't need to downgrade the
     // stability of a remote binder, since this would as an effect only restrict
     // what we can do to it.
     LOG_ALWAYS_FATAL_IF(!binder || !binder->localBinder(), "Can only downgrade local binder");
 
-    auto stability = Category::currentFromLevel(getLocalLevel());
+    auto stability = Category::currentFromLevel(level);
     status_t result = setRepr(binder.get(), stability.repr(), REPR_LOG | REPR_ALLOW_DOWNGRADE);
     LOG_ALWAYS_FATAL_IF(result != OK, "Should only mark known object.");
 }
 
+void Stability::forceDowngradeToLocalStability(const sp<IBinder>& binder) {
+    forceDowngradeToStability(binder, getLocalLevel());
+}
+
+void Stability::forceDowngradeToSystemStability(const sp<IBinder>& binder) {
+    forceDowngradeToStability(binder, Level::SYSTEM);
+}
+
+void Stability::forceDowngradeToVendorStability(const sp<IBinder>& binder) {
+    forceDowngradeToStability(binder, Level::VENDOR);
+}
+
 std::string Stability::Category::debugString() {
     return levelString(level) + " wire protocol version "
         + std::to_string(version);