Correctly manage the lifecycle of IME InputChannels.

InputChannels are normally duplicated when sent to a remote process
over Binder but this does not happen if the recipient is running within
the system server process.  This causes problems for KeyGuard because the
InputMethodManagerService may accidentally dispose the channel
that KeyGuard is using.

Fixed the lifecycle of InputChannels that are managed by the IME
framework.  We now return a duplicate of the channel to the application
and then take care to dispose of the duplicate when necessary.
In particular, InputBindResult disposes its InputChannel automatically
when returned through Binder (using PARCELABLE_WRITE_RETURN_VALUE).

Bug: 8493879
Change-Id: I08ec3d13268c76f3b56706b4523508bcefa3be79

2 files changed, 20 insertions, 2 deletions

diff --git a/core/java/android/os/Binder.java b/core/java/android/os/Binder.java
index 16b4835..e9e7551 100644
--- a/core/java/android/os/Binder.java
+++ b/core/java/android/os/Binder.java
@@ -152,7 +152,15 @@ public class Binder implements IBinder {
      * not return until the current process is exiting.
      */
     public static final native void joinThreadPool();
-    
+
+    /**
+     * Returns true if the specified interface is a proxy.
+     * @hide
+     */
+    public static final boolean isProxy(IInterface iface) {
+        return iface.asBinder() != iface;
+    }
+
     /**
      * Default constructor initializes the object.
      */
diff --git a/core/java/android/view/InputChannel.java b/core/java/android/view/InputChannel.java
index a797176..40ee1ad 100644
--- a/core/java/android/view/InputChannel.java
+++ b/core/java/android/view/InputChannel.java
@@ -54,6 +54,7 @@ public final class InputChannel implements Parcelable {
     private native void nativeTransferTo(InputChannel other);
     private native void nativeReadFromParcel(Parcel parcel);
     private native void nativeWriteToParcel(Parcel parcel);
+    private native void nativeDup(InputChannel target);
     
     private native String nativeGetName();
 
@@ -64,7 +65,7 @@ public final class InputChannel implements Parcelable {
      */
     public InputChannel() {
     }
-    
+
     @Override
     protected void finalize() throws Throwable {
         try {
@@ -125,6 +126,15 @@ public final class InputChannel implements Parcelable {
         nativeTransferTo(outParameter);
     }
 
+    /**
+     * Duplicates the input channel.
+     */
+    public InputChannel dup() {
+        InputChannel target = new InputChannel();
+        nativeDup(target);
+        return target;
+    }
+
     @Override
     public int describeContents() {
         return Parcelable.CONTENTS_FILE_DESCRIPTOR;