doc getCallingPid zero return

Bug: 297833427
Test: N/A
Change-Id: I8bd480d7deb74062f3aaf61f30b1335443f82653

1 files changed, 5 insertions, 1 deletions

diff --git a/core/java/android/os/Binder.java b/core/java/android/os/Binder.java
index 218d4bb8514f..0c753a51c508 100644
--- a/core/java/android/os/Binder.java
+++ b/core/java/android/os/Binder.java
@@ -309,7 +309,11 @@ public class Binder implements IBinder {
      * If the current thread is not currently executing an incoming transaction,
      * then its own PID is returned.
      *
-     * Warning: oneway transactions do not receive PID.
+     * Warning: oneway transactions do not receive PID. Even if you expect
+     * a transaction to be synchronous, a misbehaving client could send it
+     * as a asynchronous call and result in a 0 PID here. Additionally, if
+     * there is a race and the calling process dies, the PID may still be
+     * 0 for a synchronous call.
      */
     @CriticalNative
     public static final native int getCallingPid();