libbinder: warn when vndbinder use is wasted

We can't return null, because there may be other calls
in the process to ProcessState, but if vndservicemanager
is not installed, we can save a few threads.

Note: due to logs being broken (b/210919187) early in boot,
you may not be able to see logs for this.

Bug: 264617136
Test: check logs, e.g.
    02-14 01:31:57.034  3273  3273 E ProcessState: vndservicemanager is not started on this device, you can save resources/threads by not initializing ProcessState with /dev/vndbinder.
Change-Id: Ie91dc4ee302e7a36184e533fb755ce0870e2f546

2 files changed, 11 insertions, 0 deletions

diff --git a/libs/binder/ProcessState.cpp b/libs/binder/ProcessState.cpp
index 254dda81a6..5f1f50672a 100644
--- a/libs/binder/ProcessState.cpp
+++ b/libs/binder/ProcessState.cpp
@@ -100,6 +100,10 @@ static void verifyNotForked(bool forked) {
     LOG_ALWAYS_FATAL_IF(forked, "libbinder ProcessState can not be used after fork");
 }
 
+bool ProcessState::isVndservicemanagerEnabled() {
+    return access("/vendor/bin/vndservicemanager", R_OK) == 0;
+}
+
 sp<ProcessState> ProcessState::init(const char *driver, bool requireDefault)
 {
 #ifdef BINDER_IPC_32BIT
@@ -123,6 +127,11 @@ sp<ProcessState> ProcessState::init(const char *driver, bool requireDefault)
             driver = "/dev/binder";
         }
 
+        if (0 == strcmp(driver, "/dev/vndbinder") && !isVndservicemanagerEnabled()) {
+            ALOGE("vndservicemanager is not started on this device, you can save resources/threads "
+                  "by not initializing ProcessState with /dev/vndbinder.");
+        }
+
         // we must install these before instantiating the gProcess object,
         // otherwise this would race with creating it, and there could be the
         // possibility of an invalid gProcess object forked by another thread
diff --git a/libs/binder/include/binder/ProcessState.h b/libs/binder/include/binder/ProcessState.h
index 471c9949aa..ce578e3f5c 100644
--- a/libs/binder/include/binder/ProcessState.h
+++ b/libs/binder/include/binder/ProcessState.h
@@ -38,6 +38,8 @@ public:
     static sp<ProcessState> self();
     static sp<ProcessState> selfOrNull();
 
+    static bool isVndservicemanagerEnabled();
+
     /* initWithDriver() can be used to configure libbinder to use
      * a different binder driver dev node. It must be called *before*
      * any call to ProcessState::self(). The default is /dev/vndbinder