Merge "Add getStrongRefCountForNodeByHandle to ProcessState"b_141248619

am: 73c91ae78a

Change-Id: I96a71b7a888dac84188d7e546b0bfb9082711da8

2 files changed, 32 insertions, 0 deletions

diff --git a/libs/binder/ProcessState.cpp b/libs/binder/ProcessState.cpp
index 0336d3ebd4..ea61dc5aff 100644
--- a/libs/binder/ProcessState.cpp
+++ b/libs/binder/ProcessState.cpp
@@ -188,6 +188,30 @@ ssize_t ProcessState::getKernelReferences(size_t buf_count, uintptr_t* buf)
     return count;
 }
 
+// Queries the driver for the current strong reference count of the node
+// that the handle points to. Can only be used by the servicemanager.
+//
+// Returns -1 in case of failure, otherwise the strong reference count.
+ssize_t ProcessState::getStrongRefCountForNodeByHandle(int32_t handle) {
+    binder_node_info_for_ref info;
+    memset(&info, 0, sizeof(binder_node_info_for_ref));
+
+    info.handle = handle;
+
+    status_t result = ioctl(mDriverFD, BINDER_GET_NODE_INFO_FOR_REF, &info);
+
+    if (result != OK) {
+        static bool logged = false;
+        if (!logged) {
+          ALOGW("Kernel does not support BINDER_GET_NODE_INFO_FOR_REF.");
+          logged = true;
+        }
+        return -1;
+    }
+
+    return info.strong_count;
+}
+
 void ProcessState::setCallRestriction(CallRestriction restriction) {
     LOG_ALWAYS_FATAL_IF(IPCThreadState::selfOrNull() != nullptr,
         "Call restrictions must be set before the threadpool is started.");
diff --git a/libs/binder/include/binder/ProcessState.h b/libs/binder/include/binder/ProcessState.h
index f7c38f418d..e57ff1c260 100644
--- a/libs/binder/include/binder/ProcessState.h
+++ b/libs/binder/include/binder/ProcessState.h
@@ -69,6 +69,14 @@ public:
 
             ssize_t             getKernelReferences(size_t count, uintptr_t* buf);
 
+                                // Only usable by the context manager.
+                                // This refcount includes:
+                                // 1. Strong references to the node by this and other processes
+                                // 2. Temporary strong references held by the kernel during a
+                                //    transaction on the node.
+                                // It does NOT include local strong references to the node
+            ssize_t             getStrongRefCountForNodeByHandle(int32_t handle);
+
             enum class CallRestriction {
                 // all calls okay
                 NONE,