Add getStrongRefCountForNodeByHandle to ProcessState
ServiceManager can use this function to query individual services for their ref counts.
Bug: 143108344
Test: Manual (printed ref counts from servicemanager and confirmed that they matched the data in /d/binder/state)
Change-Id: I8c84f4b10b1c2b7690b39d1c4f4f50abd7d715b0
diff --git a/libs/binder/ProcessState.cpp b/libs/binder/ProcessState.cpp
index 0336d3e..ea61dc5 100644
--- a/libs/binder/ProcessState.cpp
+++ b/libs/binder/ProcessState.cpp
@@ -188,6 +188,30 @@
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 f7c38f4..e57ff1c 100644
--- a/libs/binder/include/binder/ProcessState.h
+++ b/libs/binder/include/binder/ProcessState.h
@@ -69,6 +69,14 @@
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,