From 287258dfb73a9b7803a5534978de5857b7711966 Mon Sep 17 00:00:00 2001
From: Yan Yan <evitayan@google.com>
Date: Mon, 8 Jan 2024 18:03:17 -0800
Subject: [PATCH] Support checking kernel bitness via JNI

Bug: 319532485
Test: Verified the return value on husky(64-bit kernel)
      and mokey_go32 (32-bit kernel)
Test: NetworkUtilsTest#testIsKernel64Bit
Change-Id: I929ce23932698b44a72ce4f35e2bd5a41ba472ee
---
 framework/jni/android_net_NetworkUtils.cpp        |  6 ++++++
 framework/src/android/net/NetworkUtils.java       |  2 ++
 tests/unit/java/android/net/NetworkUtilsTest.java | 13 ++++++++++++-
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/framework/jni/android_net_NetworkUtils.cpp b/framework/jni/android_net_NetworkUtils.cpp
index 5403be79f0..51eaf1c9b2 100644
--- a/framework/jni/android_net_NetworkUtils.cpp
+++ b/framework/jni/android_net_NetworkUtils.cpp
@@ -24,6 +24,7 @@
 #include <string.h>
 
 #include <bpf/BpfClassic.h>
+#include <bpf/KernelUtils.h>
 #include <DnsProxydProtocol.h> // NETID_USE_LOCAL_NAMESERVERS
 #include <nativehelper/JNIPlatformHelp.h>
 #include <nativehelper/ScopedPrimitiveArray.h>
@@ -250,6 +251,10 @@ static void android_net_utils_setsockoptBytes(JNIEnv *env, jclass clazz, jobject
     }
 }
 
+static jboolean android_net_utils_isKernel64Bit(JNIEnv *env, jclass clazz) {
+    return bpf::isKernel64Bit();
+}
+
 // ----------------------------------------------------------------------------
 
 /*
@@ -272,6 +277,7 @@ static const JNINativeMethod gNetworkUtilMethods[] = {
     { "getDnsNetwork", "()Landroid/net/Network;", (void*) android_net_utils_getDnsNetwork },
     { "setsockoptBytes", "(Ljava/io/FileDescriptor;II[B)V",
     (void*) android_net_utils_setsockoptBytes},
+    { "isKernel64Bit", "()Z", (void*) android_net_utils_isKernel64Bit },
 };
 // clang-format on
 
diff --git a/framework/src/android/net/NetworkUtils.java b/framework/src/android/net/NetworkUtils.java
index fbdc024340..785c029492 100644
--- a/framework/src/android/net/NetworkUtils.java
+++ b/framework/src/android/net/NetworkUtils.java
@@ -438,4 +438,6 @@ public class NetworkUtils {
     public static native void setsockoptBytes(FileDescriptor fd, int level, int option,
             byte[] value) throws ErrnoException;
 
+    /** Returns whether the Linux Kernel is 64 bit */
+    public static native boolean isKernel64Bit();
 }
diff --git a/tests/unit/java/android/net/NetworkUtilsTest.java b/tests/unit/java/android/net/NetworkUtilsTest.java
index 5d789b4cb6..2bf22112b5 100644
--- a/tests/unit/java/android/net/NetworkUtilsTest.java
+++ b/tests/unit/java/android/net/NetworkUtilsTest.java
@@ -21,8 +21,14 @@ import static android.system.OsConstants.IPPROTO_ICMPV6;
 import static android.system.OsConstants.SOCK_DGRAM;
 import static android.system.OsConstants.SOL_SOCKET;
 import static android.system.OsConstants.SO_RCVTIMEO;
+
+import static com.android.compatibility.common.util.PropertyUtil.getVsrApiLevel;
+
 import static junit.framework.Assert.assertEquals;
 
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assume.assumeTrue;
+
 import android.os.Build;
 import android.system.ErrnoException;
 import android.system.Os;
@@ -38,7 +44,6 @@ import org.junit.Test;
 import org.junit.runner.RunWith;
 
 import java.io.FileDescriptor;
-import java.io.IOException;
 import java.math.BigInteger;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
@@ -167,4 +172,10 @@ public class NetworkUtilsTest {
         assertEquals(writeTimeval, readTimeval);
         SocketUtils.closeSocketQuietly(sock);
     }
+
+    @Test
+    public void testIsKernel64Bit() {
+        assumeTrue(getVsrApiLevel() > Build.VERSION_CODES.TIRAMISU);
+        assertTrue(NetworkUtils.isKernel64Bit());
+    }
 }