feat: Call ftw() to calculate size

Change-Id: I9a25ad24cc17f31318ebfc7f0826dcfb31aee61f

source/core/rootservice/build.gradle.kts

@@ -16,6 +16,13 @@ android {
     buildFeatures {
         aidl = true
     }
+
+    externalNativeBuild {
+        cmake {
+            path("src/main/cpp/CMakeLists.txt")
+            version = "3.22.1"
+        }
+    }
 }
 
 dependencies {

source/core/rootservice/src/main/cpp/CMakeLists.txt

@@ -0,0 +1,15 @@
+cmake_minimum_required(VERSION 3.22.1)
+
+project("nativelib")
+
+add_library(${CMAKE_PROJECT_NAME} SHARED
+        nativelib.cpp
+)
+
+target_link_libraries(${CMAKE_PROJECT_NAME}
+        android
+        log
+)
+
+target_compile_options(${CMAKE_PROJECT_NAME} PRIVATE -O3 -ffunction-sections -fdata-sections -ffile-prefix-map=${CMAKE_CURRENT_SOURCE_DIR}=/src)
+target_link_libraries(${CMAKE_PROJECT_NAME} -s -flto -Wl,--gc-sections -Wl,--build-id=none -Wl,--hash-style=both)

source/core/rootservice/src/main/cpp/nativelib.cpp

@@ -0,0 +1,20 @@
+#include <jni.h>
+#include <string>
+#include <ftw.h>
+
+namespace NativeNS {
+    thread_local size_t total_size{0};
+
+    int on_walking(const char *path, const struct stat *p_stat, int flag) {
+        total_size += p_stat->st_size;
+        return 0;
+    }
+}
+
+extern "C" JNIEXPORT jlong JNICALL
+Java_com_xayah_core_rootservice_util_NativeLib_calculateSize(JNIEnv *env, jobject, jstring path) {
+    NativeNS::total_size = 0;
+    const char *p_path = env->GetStringUTFChars(path, JNI_FALSE);
+    ftw(p_path, &NativeNS::on_walking, 1024);
+    return NativeNS::total_size;
+}

source/core/rootservice/src/main/kotlin/com/xayah/core/rootservice/impl/RemoteRootServiceImpl.kt

@@ -30,6 +30,7 @@ import com.xayah.core.rootservice.parcelables.StatFsParcelable
 import com.xayah.core.rootservice.parcelables.StorageStatsParcelable
 import com.xayah.core.rootservice.util.ExceptionUtil.tryOn
 import com.xayah.core.rootservice.util.ExceptionUtil.tryWithBoolean
+import com.xayah.core.rootservice.util.NativeLib
 import com.xayah.core.rootservice.util.SsaidUtil
 import com.xayah.core.util.FileUtil
 import com.xayah.core.util.HashUtil
@@ -180,7 +181,7 @@ internal class RemoteRootServiceImpl : IRemoteRootService.Stub() {
         }
 
     override fun calculateSize(path: String): Long = synchronized(lock) {
-        FileUtil.calculateSize(path = path)
+        NativeLib.calculateSize(path)
     }
 
     override fun clearEmptyDirectoriesRecursively(path: String) = synchronized(lock) {

source/core/rootservice/src/main/kotlin/com/xayah/core/rootservice/service/RemoteRootService.kt

@@ -9,6 +9,7 @@ import android.content.pm.UserInfo
 import android.os.IBinder
 import android.os.Parcel
 import android.os.ParcelFileDescriptor
+import android.os.Process
 import android.os.RemoteException
 import android.os.UserHandle
 import com.google.gson.reflect.TypeToken
@@ -56,6 +57,11 @@ class RemoteRootService(private val context: Context) {
     private fun log(msg: () -> String) = LogUtil.log { "RemoteRootService" to msg() }
 
     class RemoteRootService : RootService() {
+        init {
+            if (Process.myUid() == 0)
+                System.loadLibrary("nativelib")
+        }
+
         override fun onBind(intent: Intent): IBinder = RemoteRootServiceImpl()
     }
 

source/core/rootservice/src/main/kotlin/com/xayah/core/rootservice/util/NativeLib.kt

@@ -0,0 +1,5 @@
+package com.xayah.core.rootservice.util
+
+object NativeLib {
+    external fun calculateSize(path: String): Long
+}