android: init user path

src/android/app/src/main/cpp/CMakeLists.txt

@@ -1,10 +1,13 @@
 cmake_minimum_required(VERSION 3.8)
 
 add_library(citra-android SHARED
-            dummy.cpp
+            native_interface.cpp
+            native_interface.h
+            ui/main/main_activity.cpp
             )
 
 # find Android's log library
 find_library(log-lib log)
 
 target_link_libraries(citra-android ${log-lib} core common inih)
+target_include_directories(citra-android PRIVATE "../../../../../" "./")

src/android/app/src/main/cpp/dummy.cpp

@@ -1,3 +0,0 @@
-int dummy(int a, int b) {
-    return a + b;
-}

src/android/app/src/main/cpp/native_interface.cpp

@@ -0,0 +1,22 @@
+// Copyright 2019 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "native_interface.h"
+
+namespace CitraJNI {
+jint JNI_OnLoad(JavaVM* vm, void* reserved) {
+    return JNI_VERSION_1_6;
+}
+
+std::string GetJString(JNIEnv* env, jstring jstr) {
+    std::string result = "";
+    if (!jstr)
+        return result;
+
+    const char* s = env->GetStringUTFChars(jstr, nullptr);
+    result = s;
+    env->ReleaseStringUTFChars(jstr, s);
+    return result;
+}
+} // namespace CitraJNI

src/android/app/src/main/cpp/native_interface.h

@@ -0,0 +1,16 @@
+// Copyright 2019 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <string>
+#include <jni.h>
+
+namespace CitraJNI {
+extern "C" {
+jint JNI_OnLoad(JavaVM* vm, void* reserved);
+}
+
+std::string GetJString(JNIEnv* env, jstring jstr);
+} // namespace CitraJNI

src/android/app/src/main/cpp/ui/main/main_activity.cpp

@@ -0,0 +1,15 @@
+// Copyright 2019 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "common/file_util.h"
+#include "native_interface.h"
+
+namespace MainActivity {
+extern "C" {
+JNICALL void Java_org_citra_1emu_citra_ui_main_MainActivity_initUserPath(JNIEnv* env, jclass type,
+                                                                         jstring path) {
+    FileUtil::SetUserPath(CitraJNI::GetJString(env, path));
+}
+};
+}; // namespace MainActivity

src/android/app/src/main/java/org/citra_emu/citra/CitraApplication.java

@@ -6,4 +6,8 @@ package org.citra_emu.citra;
 
 import android.app.Application;
 
-public class CitraApplication extends Application {}
+public class CitraApplication extends Application {
+    static {
+        System.loadLibrary("citra-android");
+    }
+}

src/android/app/src/main/java/org/citra_emu/citra/ui/main/MainActivity.java

@@ -4,15 +4,53 @@
 
 package org.citra_emu.citra.ui.main;
 
+import android.Manifest;
+import android.content.pm.PackageManager;
 import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.v7.app.AlertDialog;
 import android.support.v7.app.AppCompatActivity;
 
 import org.citra_emu.citra.R;
+import org.citra_emu.citra.utils.FileUtil;
+import org.citra_emu.citra.utils.PermissionUtil;
 
 public final class MainActivity extends AppCompatActivity {
+
+    // Java enums suck
+    private interface PermissionCodes { int INIT_USER_PATH = 0; }
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
+
+        PermissionUtil.verifyPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE,
+                                        PermissionCodes.INIT_USER_PATH);
     }
+
+    @Override
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
+                                           @NonNull int[] grantResults) {
+        switch (requestCode) {
+        case PermissionCodes.INIT_USER_PATH:
+            if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
+                initUserPath(FileUtil.getUserPath().toString());
+            } else {
+                AlertDialog.Builder dialog =
+                    new AlertDialog.Builder(this)
+                        .setTitle("Permission Error")
+                        .setMessage("Citra requires storage permissions to function.")
+                        .setCancelable(false)
+                        .setPositiveButton("OK", (dialogInterface, which) -> {
+                            PermissionUtil.verifyPermission(
+                                MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE,
+                                PermissionCodes.INIT_USER_PATH);
+                        });
+                dialog.show();
+            }
+        }
+    }
+
+    private static native void initUserPath(String path);
 }

src/android/app/src/main/java/org/citra_emu/citra/utils/FileUtil.java

@@ -0,0 +1,19 @@
+// Copyright 2019 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+package org.citra_emu.citra.utils;
+
+import android.os.Environment;
+
+import java.io.File;
+
+public class FileUtil {
+    public static File getUserPath() {
+        File storage = Environment.getExternalStorageDirectory();
+        File userPath = new File(storage, "citra");
+        if (!userPath.isDirectory())
+            userPath.mkdir();
+        return userPath;
+    }
+}

src/android/app/src/main/java/org/citra_emu/citra/utils/PermissionUtil.java

@@ -0,0 +1,32 @@
+// Copyright 2019 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+package org.citra_emu.citra.utils;
+
+import android.app.Activity;
+import android.content.pm.PackageManager;
+import android.support.v4.app.ActivityCompat;
+import android.support.v4.content.ContextCompat;
+
+public class PermissionUtil {
+
+    /**
+     * Checks a permission, if needed shows a dialog to request it
+     *
+     * @param activity    the activity requiring the permission
+     * @param permission  the permission needed
+     * @param requestCode supplied to the callback to determine the next action
+     */
+    public static void verifyPermission(Activity activity, String permission, int requestCode) {
+        if (ContextCompat.checkSelfPermission(activity, permission) ==
+            PackageManager.PERMISSION_GRANTED) {
+            // call the callback called by requestPermissions
+            activity.onRequestPermissionsResult(requestCode, new String[] {permission},
+                                                new int[] {PackageManager.PERMISSION_GRANTED});
+            return;
+        }
+
+        ActivityCompat.requestPermissions(activity, new String[] {permission}, requestCode);
+    }
+}

src/common/file_util.cpp

@@ -695,6 +695,8 @@ void SetUserPath(const std::string& path) {
 
         g_paths.emplace(UserPath::ConfigDir, user_path + CONFIG_DIR DIR_SEP);
         g_paths.emplace(UserPath::CacheDir, user_path + CACHE_DIR DIR_SEP);
+#elif ANDROID
+        ASSERT_MSG(false, "Specified path {} is not valid", path);
 #else
         if (FileUtil::Exists(ROOT_DIR DIR_SEP USERDATA_DIR)) {
             user_path = ROOT_DIR DIR_SEP USERDATA_DIR DIR_SEP;