Merge pull request #9318 from JosJuice/android-saf-games

Android: Use storage access framework for game list

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/activities/EmulationActivity.java

@@ -45,6 +45,7 @@ import org.dolphinemu.dolphinemu.fragments.SaveLoadStateFragment;
 import org.dolphinemu.dolphinemu.overlay.InputOverlay;
 import org.dolphinemu.dolphinemu.overlay.InputOverlayPointer;
 import org.dolphinemu.dolphinemu.ui.main.MainActivity;
+import org.dolphinemu.dolphinemu.ui.main.MainPresenter;
 import org.dolphinemu.dolphinemu.ui.main.TvMainActivity;
 import org.dolphinemu.dolphinemu.utils.AfterDirectoryInitializationRunner;
 import org.dolphinemu.dolphinemu.utils.ControllerMappingHelper;
@@ -164,6 +165,11 @@ public final class EmulationActivity extends AppCompatActivity
             EmulationActivity.MENU_ACTION_MOTION_CONTROLS);
   }
 
+  public static void launch(FragmentActivity activity, String filePath)
+  {
+    launch(activity, new String[]{filePath});
+  }
+
   public static void launch(FragmentActivity activity, String[] filePaths)
   {
     if (sIgnoreLaunchRequests)
@@ -410,11 +416,7 @@ public final class EmulationActivity extends AppCompatActivity
       // If the user picked a file, as opposed to just backing out.
       if (resultCode == MainActivity.RESULT_OK)
       {
-        String newDiscPath = FileBrowserHelper.getSelectedPath(result);
-        if (!TextUtils.isEmpty(newDiscPath))
-        {
-          NativeLibrary.ChangeDisc(newDiscPath);
-        }
+        NativeLibrary.ChangeDisc(result.getData().toString());
       }
     }
   }
@@ -639,8 +641,10 @@ public final class EmulationActivity extends AppCompatActivity
         break;
 
       case MENU_ACTION_CHANGE_DISC:
-        FileBrowserHelper.openFilePicker(this, REQUEST_CHANGE_DISC, false,
-                FileBrowserHelper.GAME_EXTENSIONS);
+        Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
+        intent.addCategory(Intent.CATEGORY_OPENABLE);
+        intent.setType("*/*");
+        startActivityForResult(intent, REQUEST_CHANGE_DISC);
         break;
 
       case MENU_SET_IR_SENSITIVITY:

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/settings/ui/SettingsActivity.java

@@ -25,6 +25,8 @@ import org.dolphinemu.dolphinemu.ui.main.TvMainActivity;
 import org.dolphinemu.dolphinemu.utils.FileBrowserHelper;
 import org.dolphinemu.dolphinemu.utils.TvUtil;
 
+import java.util.Set;
+
 public final class SettingsActivity extends AppCompatActivity implements SettingsActivityView
 {
   private static final String ARG_MENU_TAG = "menu_tag";
@@ -179,13 +181,19 @@ public final class SettingsActivity extends AppCompatActivity implements Setting
     // If the user picked a file, as opposed to just backing out.
     if (resultCode == MainActivity.RESULT_OK)
     {
-      if (requestCode == MainPresenter.REQUEST_SD_FILE)
+      if (requestCode != MainPresenter.REQUEST_DIRECTORY)
       {
         Uri uri = canonicalizeIfPossible(result.getData());
-        int takeFlags = result.getFlags() &
-                (Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
 
-        FileBrowserHelper.runAfterExtensionCheck(this, uri, FileBrowserHelper.RAW_EXTENSION, () ->
+        Set<String> validExtensions = requestCode == MainPresenter.REQUEST_GAME_FILE ?
+                FileBrowserHelper.GAME_EXTENSIONS : FileBrowserHelper.RAW_EXTENSION;
+
+        int flags = Intent.FLAG_GRANT_READ_URI_PERMISSION;
+        if (requestCode != MainPresenter.REQUEST_GAME_FILE)
+          flags |= Intent.FLAG_GRANT_WRITE_URI_PERMISSION;
+        int takeFlags = flags & result.getFlags();
+
+        FileBrowserHelper.runAfterExtensionCheck(this, uri, validExtensions, () ->
         {
           getContentResolver().takePersistableUriPermission(uri, takeFlags);
           getFragment().getAdapter().onFilePickerConfirmation(uri.toString());

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/settings/ui/SettingsAdapter.java

@@ -306,9 +306,6 @@ public final class SettingsAdapter extends RecyclerView.Adapter<SettingViewHolde
     mClickedPosition = position;
     FilePicker filePicker = (FilePicker) item;
 
-    switch (filePicker.getRequestType())
-    {
-      case MainPresenter.REQUEST_SD_FILE:
     Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
     intent.addCategory(Intent.CATEGORY_OPENABLE);
     intent.setType("*/*");
@@ -320,14 +317,6 @@ public final class SettingsAdapter extends RecyclerView.Adapter<SettingViewHolde
     }
 
     mView.getActivity().startActivityForResult(intent, filePicker.getRequestType());
-        break;
-      case MainPresenter.REQUEST_GAME_FILE:
-        FileBrowserHelper.openFilePicker(mView.getActivity(), filePicker.getRequestType(), false,
-                FileBrowserHelper.GAME_EXTENSIONS);
-        break;
-      default:
-        throw new InvalidParameterException("Unhandled request code");
-    }
   }
 
   public void onFilePickerConfirmation(String selectedFile)

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/settings/utils/SettingsFile.java

@@ -16,6 +16,9 @@ import java.io.File;
  */
 public final class SettingsFile
 {
+  public static final String KEY_ISO_PATH_BASE = "ISOPath";
+  public static final String KEY_ISO_PATHS = "ISOPaths";
+
   public static final String KEY_GCPAD_TYPE = "SIDevice";
   public static final String KEY_GCPAD_PLAYER_1 = "SIDevice0";
   public static final String KEY_GCPAD_G_TYPE = "PadType";

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/model/GameFileCache.java

@@ -1,22 +1,19 @@
 package org.dolphinemu.dolphinemu.model;
 
-import android.content.Context;
-import android.content.SharedPreferences;
-import android.preference.PreferenceManager;
-
 import androidx.annotation.Keep;
 
+import org.dolphinemu.dolphinemu.NativeLibrary;
 import org.dolphinemu.dolphinemu.features.settings.model.BooleanSetting;
+import org.dolphinemu.dolphinemu.features.settings.model.Settings;
+import org.dolphinemu.dolphinemu.features.settings.utils.SettingsFile;
+import org.dolphinemu.dolphinemu.utils.ContentHandler;
+import org.dolphinemu.dolphinemu.utils.IniFile;
 
 import java.io.File;
-import java.util.HashSet;
-import java.util.Set;
+import java.util.LinkedHashSet;
 
 public class GameFileCache
 {
-  private static final String GAME_FOLDER_PATHS_PREFERENCE = "gameFolderPaths";
-  private static final Set<String> EMPTY_SET = new HashSet<>();
-
   @Keep
   private long mPointer;
 
@@ -30,70 +27,83 @@ public class GameFileCache
   @Override
   public native void finalize();
 
-  public static void addGameFolder(String path, Context context)
+  public static void addGameFolder(String path)
   {
-    SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
-    Set<String> folderPaths = preferences.getStringSet(GAME_FOLDER_PATHS_PREFERENCE, EMPTY_SET);
+    File dolphinFile = SettingsFile.getSettingsFile(Settings.FILE_DOLPHIN);
+    IniFile dolphinIni = new IniFile(dolphinFile);
+    LinkedHashSet<String> pathSet = getPathSet(false);
+    int totalISOPaths =
+            dolphinIni.getInt(Settings.SECTION_INI_GENERAL, SettingsFile.KEY_ISO_PATHS, 0);
 
-    if (folderPaths == null)
+    if (!pathSet.contains(path))
     {
-      return;
-    }
-
-    Set<String> newFolderPaths = new HashSet<>(folderPaths);
-    newFolderPaths.add(path);
-    SharedPreferences.Editor editor = preferences.edit();
-    editor.putStringSet(GAME_FOLDER_PATHS_PREFERENCE, newFolderPaths);
-    editor.apply();
-  }
-
-  private void removeNonExistentGameFolders(Context context)
-  {
-    SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
-    Set<String> folderPaths = preferences.getStringSet(GAME_FOLDER_PATHS_PREFERENCE, EMPTY_SET);
-
-    if (folderPaths == null)
-    {
-      return;
-    }
-
-    Set<String> newFolderPaths = new HashSet<>();
-    for (String folderPath : folderPaths)
-    {
-      File folder = new File(folderPath);
-      if (folder.exists())
-      {
-        newFolderPaths.add(folderPath);
+      dolphinIni.setInt(Settings.SECTION_INI_GENERAL, SettingsFile.KEY_ISO_PATHS,
+              totalISOPaths + 1);
+      dolphinIni.setString(Settings.SECTION_INI_GENERAL, SettingsFile.KEY_ISO_PATH_BASE +
+              totalISOPaths, path);
+      dolphinIni.save(dolphinFile);
+      NativeLibrary.ReloadConfig();
     }
   }
 
-    if (folderPaths.size() != newFolderPaths.size())
+  private static LinkedHashSet<String> getPathSet(boolean removeNonExistentFolders)
   {
-      // One or more folders are being deleted
-      SharedPreferences.Editor editor = preferences.edit();
-      editor.putStringSet(GAME_FOLDER_PATHS_PREFERENCE, newFolderPaths);
-      editor.apply();
+    File dolphinFile = SettingsFile.getSettingsFile(Settings.FILE_DOLPHIN);
+    IniFile dolphinIni = new IniFile(dolphinFile);
+    LinkedHashSet<String> pathSet = new LinkedHashSet<>();
+    int totalISOPaths =
+            dolphinIni.getInt(Settings.SECTION_INI_GENERAL, SettingsFile.KEY_ISO_PATHS, 0);
+
+    for (int i = 0; i < totalISOPaths; i++)
+    {
+      String path = dolphinIni.getString(Settings.SECTION_INI_GENERAL,
+              SettingsFile.KEY_ISO_PATH_BASE + i, "");
+
+      if (path.startsWith("content://") ? ContentHandler.exists(path) : new File(path).exists())
+      {
+        pathSet.add(path);
       }
     }
 
+    if (removeNonExistentFolders && totalISOPaths > pathSet.size())
+    {
+      int setIndex = 0;
+
+      dolphinIni.setInt(Settings.SECTION_INI_GENERAL, SettingsFile.KEY_ISO_PATHS,
+              pathSet.size());
+
+      // One or more folders have been removed.
+      for (String entry : pathSet)
+      {
+        dolphinIni.setString(Settings.SECTION_INI_GENERAL, SettingsFile.KEY_ISO_PATH_BASE +
+                setIndex, entry);
+
+        setIndex++;
+      }
+
+      // Delete known unnecessary keys. Ignore i values beyond totalISOPaths.
+      for (int i = setIndex; i < totalISOPaths; i++)
+      {
+        dolphinIni.deleteKey(Settings.SECTION_INI_GENERAL, SettingsFile.KEY_ISO_PATH_BASE + i);
+      }
+
+      dolphinIni.save(dolphinFile);
+      NativeLibrary.ReloadConfig();
+    }
+
+    return pathSet;
+  }
+
   /**
    * Scans through the file system and updates the cache to match.
    *
    * @return true if the cache was modified
    */
-  public boolean scanLibrary(Context context)
+  public boolean scanLibrary()
   {
     boolean recursiveScan = BooleanSetting.MAIN_RECURSIVE_ISO_PATHS.getBooleanGlobal();
 
-    removeNonExistentGameFolders(context);
-
-    SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
-    Set<String> folderPathsSet = preferences.getStringSet(GAME_FOLDER_PATHS_PREFERENCE, EMPTY_SET);
-
-    if (folderPathsSet == null)
-    {
-      return false;
-    }
+    LinkedHashSet<String> folderPathsSet = getPathSet(true);
 
     String[] folderPaths = folderPathsSet.toArray(new String[0]);
 

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/services/GameFileCacheService.java

@@ -29,9 +29,10 @@ public final class GameFileCacheService extends IntentService
   private static final String ACTION_RESCAN = "org.dolphinemu.dolphinemu.RESCAN_GAME_FILE_CACHE";
 
   private static GameFileCache gameFileCache = null;
-  private static AtomicReference<GameFile[]> gameFiles = new AtomicReference<>(new GameFile[]{});
-  private static AtomicBoolean hasLoadedCache = new AtomicBoolean(false);
-  private static AtomicBoolean hasScannedLibrary = new AtomicBoolean(false);
+  private static final AtomicReference<GameFile[]> gameFiles =
+          new AtomicReference<>(new GameFile[]{});
+  private static final AtomicBoolean hasLoadedCache = new AtomicBoolean(false);
+  private static final AtomicBoolean hasScannedLibrary = new AtomicBoolean(false);
 
   public GameFileCacheService()
   {
@@ -166,7 +167,7 @@ public final class GameFileCacheService extends IntentService
     {
       synchronized (gameFileCache)
       {
-        boolean changed = gameFileCache.scanLibrary(this);
+        boolean changed = gameFileCache.scanLibrary();
         if (changed)
           updateGameFileArray();
         hasScannedLibrary.set(true);

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/ui/main/MainActivity.java

@@ -2,6 +2,7 @@ package org.dolphinemu.dolphinemu.ui.main;
 
 import android.content.Intent;
 import android.content.pm.PackageManager;
+import android.net.Uri;
 import android.os.Bundle;
 import android.view.Menu;
 import android.view.MenuInflater;
@@ -45,7 +46,7 @@ public final class MainActivity extends AppCompatActivity implements MainView
   private FloatingActionButton mFab;
   private static boolean sShouldRescanLibrary = true;
 
-  private MainPresenter mPresenter = new MainPresenter(this, this);
+  private final MainPresenter mPresenter = new MainPresenter(this, this);
 
   @Override
   protected void onCreate(Bundle savedInstanceState)
@@ -85,7 +86,7 @@ public final class MainActivity extends AppCompatActivity implements MainView
               .run(this, false, this::setPlatformTabsAndStartGameFileCacheService);
     }
 
-    mPresenter.addDirIfNeeded(this);
+    mPresenter.addDirIfNeeded();
 
     // In case the user changed a setting that affects how games are displayed,
     // such as system language, cover downloading...
@@ -162,14 +163,17 @@ public final class MainActivity extends AppCompatActivity implements MainView
   @Override
   public void launchFileListActivity()
   {
-    FileBrowserHelper.openDirectoryPicker(this, FileBrowserHelper.GAME_EXTENSIONS);
+    Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);
+    startActivityForResult(intent, MainPresenter.REQUEST_DIRECTORY);
   }
 
   @Override
   public void launchOpenFileActivity()
   {
-    FileBrowserHelper.openFilePicker(this, MainPresenter.REQUEST_GAME_FILE, false,
-            FileBrowserHelper.GAME_EXTENSIONS);
+    Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
+    intent.addCategory(Intent.CATEGORY_OPENABLE);
+    intent.setType("*/*");
+    startActivityForResult(intent, MainPresenter.REQUEST_GAME_FILE);
   }
 
   @Override
@@ -194,19 +198,21 @@ public final class MainActivity extends AppCompatActivity implements MainView
     // If the user picked a file, as opposed to just backing out.
     if (resultCode == MainActivity.RESULT_OK)
     {
+      Uri uri = result.getData();
       switch (requestCode)
       {
         case MainPresenter.REQUEST_DIRECTORY:
-          mPresenter.onDirectorySelected(FileBrowserHelper.getSelectedPath(result));
+          mPresenter.onDirectorySelected(result);
           break;
 
         case MainPresenter.REQUEST_GAME_FILE:
-          EmulationActivity.launch(this, FileBrowserHelper.getSelectedFiles(result));
+          FileBrowserHelper.runAfterExtensionCheck(this, uri,
+                  FileBrowserHelper.GAME_LIKE_EXTENSIONS,
+                  () -> EmulationActivity.launch(this, result.getData().toString()));
           break;
 
         case MainPresenter.REQUEST_WAD_FILE:
-          FileBrowserHelper.runAfterExtensionCheck(this, result.getData(),
-                  FileBrowserHelper.WAD_EXTENSION,
+          FileBrowserHelper.runAfterExtensionCheck(this, uri, FileBrowserHelper.WAD_EXTENSION,
                   () -> mPresenter.installWAD(result.getData().toString()));
           break;
       }

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/ui/main/MainPresenter.java

@@ -2,9 +2,11 @@ package org.dolphinemu.dolphinemu.ui.main;
 
 import android.app.Activity;
 import android.content.BroadcastReceiver;
+import android.content.ContentResolver;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
+import android.net.Uri;
 import android.widget.Toast;
 
 import androidx.appcompat.app.AlertDialog;
@@ -13,10 +15,16 @@ import androidx.localbroadcastmanager.content.LocalBroadcastManager;
 import org.dolphinemu.dolphinemu.BuildConfig;
 import org.dolphinemu.dolphinemu.NativeLibrary;
 import org.dolphinemu.dolphinemu.R;
+import org.dolphinemu.dolphinemu.features.settings.model.BooleanSetting;
 import org.dolphinemu.dolphinemu.features.settings.ui.MenuTag;
 import org.dolphinemu.dolphinemu.model.GameFileCache;
 import org.dolphinemu.dolphinemu.services.GameFileCacheService;
 import org.dolphinemu.dolphinemu.utils.AfterDirectoryInitializationRunner;
+import org.dolphinemu.dolphinemu.utils.ContentHandler;
+import org.dolphinemu.dolphinemu.utils.FileBrowserHelper;
+
+import java.util.Arrays;
+import java.util.Set;
 
 public final class MainPresenter
 {
@@ -95,18 +103,40 @@ public final class MainPresenter
     return false;
   }
 
-  public void addDirIfNeeded(Context context)
+  public void addDirIfNeeded()
   {
     if (mDirToAdd != null)
     {
-      GameFileCache.addGameFolder(mDirToAdd, context);
+      GameFileCache.addGameFolder(mDirToAdd);
       mDirToAdd = null;
     }
   }
 
-  public void onDirectorySelected(String dir)
+  public void onDirectorySelected(Intent result)
   {
-    mDirToAdd = dir;
+    Uri uri = result.getData();
+
+    boolean recursive = BooleanSetting.MAIN_RECURSIVE_ISO_PATHS.getBooleanGlobal();
+    String[] childNames = ContentHandler.getChildNames(uri, recursive);
+    if (Arrays.stream(childNames).noneMatch((name) -> FileBrowserHelper.GAME_EXTENSIONS.contains(
+            FileBrowserHelper.getExtension(name, false))))
+    {
+      AlertDialog.Builder builder = new AlertDialog.Builder(mContext, R.style.DolphinDialogBase);
+      builder.setMessage(mContext.getString(R.string.wrong_file_extension_in_directory,
+              FileBrowserHelper.setToSortedDelimitedString(FileBrowserHelper.GAME_EXTENSIONS)));
+      builder.setPositiveButton(R.string.ok, null);
+      builder.show();
+    }
+
+    ContentResolver contentResolver = mContext.getContentResolver();
+    Uri canonicalizedUri = contentResolver.canonicalize(uri);
+    if (canonicalizedUri != null)
+      uri = canonicalizedUri;
+
+    int takeFlags = result.getFlags() & Intent.FLAG_GRANT_READ_URI_PERMISSION;
+    mContext.getContentResolver().takePersistableUriPermission(uri, takeFlags);
+
+    mDirToAdd = uri.toString();
   }
 
   public void installWAD(String file)

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/ui/main/TvMainActivity.java

@@ -2,6 +2,7 @@ package org.dolphinemu.dolphinemu.ui.main;
 
 import android.content.Intent;
 import android.content.pm.PackageManager;
+import android.net.Uri;
 import android.os.Bundle;
 import android.widget.Toast;
 
@@ -39,11 +40,11 @@ public final class TvMainActivity extends FragmentActivity implements MainView
 {
   private static boolean sShouldRescanLibrary = true;
 
-  private MainPresenter mPresenter = new MainPresenter(this, this);
+  private final MainPresenter mPresenter = new MainPresenter(this, this);
 
   private BrowseSupportFragment mBrowseFragment;
 
-  private ArrayList<ArrayObjectAdapter> mGameRows = new ArrayList<>();
+  private final ArrayList<ArrayObjectAdapter> mGameRows = new ArrayList<>();
 
   @Override
   protected void onCreate(Bundle savedInstanceState)
@@ -73,7 +74,7 @@ public final class TvMainActivity extends FragmentActivity implements MainView
       GameFileCacheService.startLoad(this);
     }
 
-    mPresenter.addDirIfNeeded(this);
+    mPresenter.addDirIfNeeded();
 
     // In case the user changed a setting that affects how games are displayed,
     // such as system language, cover downloading...
@@ -167,14 +168,17 @@ public final class TvMainActivity extends FragmentActivity implements MainView
   @Override
   public void launchFileListActivity()
   {
-    FileBrowserHelper.openDirectoryPicker(this, FileBrowserHelper.GAME_EXTENSIONS);
+    Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);
+    startActivityForResult(intent, MainPresenter.REQUEST_DIRECTORY);
   }
 
   @Override
   public void launchOpenFileActivity()
   {
-    FileBrowserHelper.openFilePicker(this, MainPresenter.REQUEST_GAME_FILE, false,
-            FileBrowserHelper.GAME_EXTENSIONS);
+    Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
+    intent.addCategory(Intent.CATEGORY_OPENABLE);
+    intent.setType("*/*");
+    startActivityForResult(intent, MainPresenter.REQUEST_GAME_FILE);
   }
 
   @Override
@@ -218,19 +222,21 @@ public final class TvMainActivity extends FragmentActivity implements MainView
     // If the user picked a file, as opposed to just backing out.
     if (resultCode == MainActivity.RESULT_OK)
     {
+      Uri uri = result.getData();
       switch (requestCode)
       {
         case MainPresenter.REQUEST_DIRECTORY:
-          mPresenter.onDirectorySelected(FileBrowserHelper.getSelectedPath(result));
+          mPresenter.onDirectorySelected(result);
           break;
 
         case MainPresenter.REQUEST_GAME_FILE:
-          EmulationActivity.launch(this, FileBrowserHelper.getSelectedFiles(result));
+          FileBrowserHelper.runAfterExtensionCheck(this, uri,
+                  FileBrowserHelper.GAME_LIKE_EXTENSIONS,
+                  () -> EmulationActivity.launch(this, result.getData().toString()));
           break;
 
         case MainPresenter.REQUEST_WAD_FILE:
-          FileBrowserHelper.runAfterExtensionCheck(this, result.getData(),
-                  FileBrowserHelper.WAD_EXTENSION,
+          FileBrowserHelper.runAfterExtensionCheck(this, uri, FileBrowserHelper.WAD_EXTENSION,
                   () -> mPresenter.installWAD(result.getData().toString()));
           break;
       }

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/utils/ContentHandler.java

@@ -14,54 +14,76 @@ import androidx.annotation.Keep;
 import org.dolphinemu.dolphinemu.DolphinApplication;
 
 import java.io.FileNotFoundException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.Predicate;
+
+/*
+  We use a lot of "catch (Exception e)" in this class. This is for two reasons:
+
+  1. We don't want any exceptions to escape to native code, as this leads to nasty crashes
+     that often don't have stack traces that make sense.
+
+  2. The sheer number of different exceptions, both documented and undocumented. These include:
+     - FileNotFoundException when a file doesn't exist
+     - FileNotFoundException when using an invalid open mode (according to the documentation)
+     - IllegalArgumentException when using an invalid open mode (in practice with FileProvider)
+     - IllegalArgumentException when providing a tree where a document was expected and vice versa
+     - SecurityException when trying to access something the user hasn't granted us permission to
+     - UnsupportedOperationException when a URI specifies a storage provider that doesn't exist
+ */
 
 public class ContentHandler
 {
   @Keep
-  public static int openFd(String uri, String mode)
+  public static int openFd(@NonNull String uri, @NonNull String mode)
   {
     try
     {
-      return getContentResolver().openFileDescriptor(Uri.parse(uri), mode).detachFd();
+      return getContentResolver().openFileDescriptor(unmangle(uri), mode).detachFd();
     }
     catch (SecurityException e)
     {
       Log.error("Tried to open " + uri + " without permission");
-      return -1;
     }
-    // Some content providers throw IllegalArgumentException for invalid modes,
-    // despite the documentation saying that invalid modes result in a FileNotFoundException
-    catch (FileNotFoundException | IllegalArgumentException | NullPointerException e)
+    catch (Exception ignored)
     {
-      return -1;
     }
+
+    return -1;
   }
 
   @Keep
-  public static boolean delete(String uri)
+  public static boolean delete(@NonNull String uri)
   {
     try
     {
-      return DocumentsContract.deleteDocument(getContentResolver(), Uri.parse(uri));
-    }
-    catch (SecurityException e)
-    {
-      Log.error("Tried to delete " + uri + " without permission");
-      return false;
+      return DocumentsContract.deleteDocument(getContentResolver(), unmangle(uri));
     }
     catch (FileNotFoundException e)
     {
       // Return true because we care about the file not being there, not the actual delete.
       return true;
     }
+    catch (SecurityException e)
+    {
+      Log.error("Tried to delete " + uri + " without permission");
+    }
+    catch (Exception ignored)
+    {
+    }
+
+    return false;
   }
 
   public static boolean exists(@NonNull String uri)
   {
     try
     {
+      Uri documentUri = treeToDocument(unmangle(uri));
       final String[] projection = new String[]{Document.COLUMN_MIME_TYPE, Document.COLUMN_SIZE};
-      try (Cursor cursor = getContentResolver().query(Uri.parse(uri), projection, null, null, null))
+      try (Cursor cursor = getContentResolver().query(documentUri, projection, null, null, null))
       {
         return cursor != null && cursor.getCount() > 0;
       }
@@ -70,15 +92,65 @@ public class ContentHandler
     {
       Log.error("Tried to check if " + uri + " exists without permission");
     }
+    catch (Exception ignored)
+    {
+    }
 
     return false;
   }
 
+  /**
+   * @return -1 if not found, -2 if directory, file size otherwise
+   */
+  @Keep
+  public static long getSizeAndIsDirectory(@NonNull String uri)
+  {
+    try
+    {
+      Uri documentUri = treeToDocument(unmangle(uri));
+      final String[] projection = new String[]{Document.COLUMN_MIME_TYPE, Document.COLUMN_SIZE};
+      try (Cursor cursor = getContentResolver().query(documentUri, projection, null, null, null))
+      {
+        if (cursor != null && cursor.moveToFirst())
+        {
+          if (Document.MIME_TYPE_DIR.equals(cursor.getString(0)))
+            return -2;
+          else
+            return cursor.isNull(1) ? 0 : cursor.getLong(1);
+        }
+      }
+    }
+    catch (SecurityException e)
+    {
+      Log.error("Tried to get metadata for " + uri + " without permission");
+    }
+    catch (Exception ignored)
+    {
+    }
+
+    return -1;
+  }
+
+  @Nullable @Keep
+  public static String getDisplayName(@NonNull String uri)
+  {
+    try
+    {
+      return getDisplayName(unmangle(uri));
+    }
+    catch (Exception ignored)
+    {
+    }
+
+    return null;
+  }
+
   @Nullable
   public static String getDisplayName(@NonNull Uri uri)
   {
     final String[] projection = new String[]{Document.COLUMN_DISPLAY_NAME};
-    try (Cursor cursor = getContentResolver().query(uri, projection, null, null, null))
+    Uri documentUri = treeToDocument(uri);
+    try (Cursor cursor = getContentResolver().query(documentUri, projection, null, null, null))
     {
       if (cursor != null && cursor.moveToFirst())
       {
@@ -89,10 +161,257 @@ public class ContentHandler
     {
       Log.error("Tried to get display name of " + uri + " without permission");
     }
+    catch (Exception ignored)
+    {
+    }
 
     return null;
   }
 
+  @NonNull @Keep
+  public static String[] getChildNames(@NonNull String uri, boolean recursive)
+  {
+    try
+    {
+      return getChildNames(unmangle(uri), recursive);
+    }
+    catch (Exception ignored)
+    {
+    }
+
+    return new String[0];
+  }
+
+  @NonNull
+  public static String[] getChildNames(@NonNull Uri uri, boolean recursive)
+  {
+    ArrayList<String> result = new ArrayList<>();
+
+    ForEachChildCallback callback = new ForEachChildCallback()
+    {
+      @Override
+      public void run(String displayName, String documentId, boolean isDirectory)
+      {
+        if (recursive && isDirectory)
+        {
+          forEachChild(uri, documentId, this);
+        }
+        else
+        {
+          result.add(displayName);
+        }
+      }
+    };
+
+    forEachChild(uri, DocumentsContract.getDocumentId(treeToDocument(uri)), callback);
+
+    return result.toArray(new String[0]);
+  }
+
+  @NonNull @Keep
+  public static String[] doFileSearch(@NonNull String directory, @NonNull String[] extensions,
+          boolean recursive)
+  {
+    ArrayList<String> result = new ArrayList<>();
+
+    try
+    {
+      Uri uri = unmangle(directory);
+      String documentId = DocumentsContract.getDocumentId(treeToDocument(uri));
+      boolean acceptAll = extensions.length == 0;
+      Predicate<String> extensionCheck = (displayName) ->
+      {
+        String extension = FileBrowserHelper.getExtension(displayName, true);
+        return extension != null && Arrays.stream(extensions).anyMatch(extension::equalsIgnoreCase);
+      };
+      doFileSearch(uri, directory, documentId, recursive, result, acceptAll, extensionCheck);
+    }
+    catch (Exception ignored)
+    {
+    }
+
+    return result.toArray(new String[0]);
+  }
+
+  private static void doFileSearch(@NonNull Uri baseUri, @NonNull String path,
+          @NonNull String documentId, boolean recursive, @NonNull List<String> resultOut,
+          boolean acceptAll, @NonNull Predicate<String> extensionCheck)
+  {
+    forEachChild(baseUri, documentId, (displayName, childDocumentId, isDirectory) ->
+    {
+      String childPath = path + '/' + displayName;
+      if (acceptAll || (!isDirectory && extensionCheck.test(displayName)))
+      {
+        resultOut.add(childPath);
+      }
+      if (recursive && isDirectory)
+      {
+        doFileSearch(baseUri, childPath, childDocumentId, recursive, resultOut, acceptAll,
+                extensionCheck);
+      }
+    });
+  }
+
+  private interface ForEachChildCallback
+  {
+    void run(String displayName, String documentId, boolean isDirectory);
+  }
+
+  private static void forEachChild(@NonNull Uri uri, @NonNull String documentId,
+          @NonNull ForEachChildCallback callback)
+  {
+    try
+    {
+      Uri childrenUri = DocumentsContract.buildChildDocumentsUriUsingTree(uri, documentId);
+
+      final String[] projection = new String[]{Document.COLUMN_DISPLAY_NAME,
+              Document.COLUMN_MIME_TYPE, Document.COLUMN_DOCUMENT_ID};
+      try (Cursor cursor = getContentResolver().query(childrenUri, projection, null, null, null))
+      {
+        if (cursor != null)
+        {
+          while (cursor.moveToNext())
+          {
+            callback.run(cursor.getString(0), cursor.getString(2),
+                    Document.MIME_TYPE_DIR.equals(cursor.getString(1)));
+          }
+        }
+      }
+    }
+    catch (SecurityException e)
+    {
+      Log.error("Tried to get children of " + uri + " without permission");
+    }
+    catch (Exception ignored)
+    {
+    }
+  }
+
+  @NonNull
+  private static Uri getChild(@NonNull Uri parentUri, @NonNull String childName)
+          throws FileNotFoundException, SecurityException
+  {
+    String parentId = DocumentsContract.getDocumentId(treeToDocument(parentUri));
+    Uri childrenUri = DocumentsContract.buildChildDocumentsUriUsingTree(parentUri, parentId);
+
+    final String[] projection = new String[]{Document.COLUMN_DISPLAY_NAME,
+            Document.COLUMN_DOCUMENT_ID};
+    final String selection = Document.COLUMN_DISPLAY_NAME + "=?";
+    final String[] selectionArgs = new String[]{childName};
+    try (Cursor cursor = getContentResolver().query(childrenUri, projection, selection,
+            selectionArgs, null))
+    {
+      if (cursor != null)
+      {
+        while (cursor.moveToNext())
+        {
+          // FileProvider seemingly doesn't support selections, so we have to manually filter here
+          if (childName.equals(cursor.getString(0)))
+          {
+            return DocumentsContract.buildDocumentUriUsingTree(parentUri, cursor.getString(1));
+          }
+        }
+      }
+    }
+    catch (SecurityException e)
+    {
+      Log.error("Tried to get child " + childName + " of " + parentUri + " without permission");
+    }
+    catch (Exception ignored)
+    {
+    }
+
+    throw new FileNotFoundException(parentUri + "/" + childName);
+  }
+
+  /**
+   * Since our C++ code was written under the assumption that it would be running under a filesystem
+   * which supports normal paths, it appends a slash followed by a file name when it wants to access
+   * a file in a directory. This function translates that into the type of URI that SAF requires.
+   *
+   * In order to detect whether a URI is mangled or not, we make the assumption that an
+   * unmangled URI contains at least one % and does not contain any slashes after the last %.
+   * This seems to hold for all common storage providers, but it is theoretically for a storage
+   * provider to use URIs without any % characters.
+   */
+  @NonNull
+  private static Uri unmangle(@NonNull String uri) throws FileNotFoundException, SecurityException
+  {
+    int lastComponentEnd = getLastComponentEnd(uri);
+    int lastComponentStart = getLastComponentStart(uri, lastComponentEnd);
+
+    if (lastComponentStart == 0)
+    {
+      return Uri.parse(uri.substring(0, lastComponentEnd));
+    }
+    else
+    {
+      Uri parentUri = unmangle(uri.substring(0, lastComponentStart));
+      String childName = uri.substring(lastComponentStart, lastComponentEnd);
+      return getChild(parentUri, childName);
+    }
+  }
+
+  /**
+   * Returns the last character which is not a slash.
+   */
+  private static int getLastComponentEnd(@NonNull String uri)
+  {
+    int i = uri.length();
+    while (i > 0 && uri.charAt(i - 1) == '/')
+      i--;
+    return i;
+  }
+
+  /**
+   * Scans backwards starting from lastComponentEnd and returns the index after the first slash
+   * it finds, but only if there is a % before that slash and there is no % after it.
+   */
+  private static int getLastComponentStart(@NonNull String uri, int lastComponentEnd)
+  {
+    int i = lastComponentEnd;
+    while (i > 0 && uri.charAt(i - 1) != '/')
+    {
+      i--;
+      if (uri.charAt(i) == '%')
+        return 0;
+    }
+
+    int j = i;
+    while (j > 0)
+    {
+      j--;
+      if (uri.charAt(j) == '%')
+        return i;
+    }
+
+    return 0;
+  }
+
+  @NonNull
+  private static Uri treeToDocument(@NonNull Uri uri)
+  {
+    if (isTreeUri(uri))
+    {
+      String documentId = DocumentsContract.getTreeDocumentId(uri);
+      return DocumentsContract.buildDocumentUriUsingTree(uri, documentId);
+    }
+    else
+    {
+      return uri;
+    }
+  }
+
+  /**
+   * This is like DocumentsContract.isTreeUri, except it doesn't return true for URIs like
+   * content://com.example/tree/12/document/24/. We want to treat those as documents, not trees.
+   */
+  private static boolean isTreeUri(@NonNull Uri uri)
+  {
+    final List<String> pathSegments = uri.getPathSegments();
+    return pathSegments.size() == 2 && "tree".equals(pathSegments.get(0));
+  }
+
   private static ContentResolver getContentResolver()
   {
     return DolphinApplication.getAppContext().getContentResolver();

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/utils/FileBrowserHelper.java

@@ -28,7 +28,14 @@ import java.util.Set;
 public final class FileBrowserHelper
 {
   public static final HashSet<String> GAME_EXTENSIONS = new HashSet<>(Arrays.asList(
-          "gcm", "tgc", "iso", "ciso", "gcz", "wbfs", "wia", "rvz", "wad", "dol", "elf", "dff"));
+          "gcm", "tgc", "iso", "ciso", "gcz", "wbfs", "wia", "rvz", "wad", "dol", "elf"));
+
+  public static final HashSet<String> GAME_LIKE_EXTENSIONS = new HashSet<>(GAME_EXTENSIONS);
+
+  static
+  {
+    GAME_LIKE_EXTENSIONS.add("dff");
+  }
 
   public static final HashSet<String> RAW_EXTENSION = new HashSet<>(Collections.singletonList(
           "raw"));
@@ -50,21 +57,6 @@ public final class FileBrowserHelper
     activity.startActivityForResult(i, MainPresenter.REQUEST_DIRECTORY);
   }
 
-  public static void openFilePicker(FragmentActivity activity, int requestCode, boolean allowMulti,
-          HashSet<String> extensions)
-  {
-    Intent i = new Intent(activity, CustomFilePickerActivity.class);
-
-    i.putExtra(FilePickerActivity.EXTRA_ALLOW_MULTIPLE, allowMulti);
-    i.putExtra(FilePickerActivity.EXTRA_ALLOW_CREATE_DIR, false);
-    i.putExtra(FilePickerActivity.EXTRA_MODE, FilePickerActivity.MODE_FILE);
-    i.putExtra(FilePickerActivity.EXTRA_START_PATH,
-            Environment.getExternalStorageDirectory().getPath());
-    i.putExtra(CustomFilePickerActivity.EXTRA_EXTENSIONS, extensions);
-
-    activity.startActivityForResult(i, requestCode);
-  }
-
   @Nullable
   public static String getSelectedPath(Intent result)
   {
@@ -79,22 +71,6 @@ public final class FileBrowserHelper
     return null;
   }
 
-  @Nullable
-  public static String[] getSelectedFiles(Intent result)
-  {
-    // Use the provided utility method to parse the result
-    List<Uri> files = Utils.getSelectedFilesFromResult(result);
-    if (!files.isEmpty())
-    {
-      String[] paths = new String[files.size()];
-      for (int i = 0; i < files.size(); i++)
-        paths[i] = Utils.getFileForUri(files.get(i)).getAbsolutePath();
-      return paths;
-    }
-
-    return null;
-  }
-
   public static boolean isPathEmptyOrValid(StringSetting path)
   {
     return isPathEmptyOrValid(path.getStringGlobal());
@@ -112,10 +88,10 @@ public final class FileBrowserHelper
 
     String path = uri.getLastPathSegment();
     if (path != null)
-      extension = getExtension(new File(path).getName());
+      extension = getExtension(new File(path).getName(), false);
 
     if (extension == null)
-      extension = getExtension(ContentHandler.getDisplayName(uri));
+      extension = getExtension(ContentHandler.getDisplayName(uri), false);
 
     if (extension != null && validExtensions.contains(extension))
     {
@@ -133,10 +109,8 @@ public final class FileBrowserHelper
       int messageId = validExtensions.size() == 1 ?
               R.string.wrong_file_extension_single : R.string.wrong_file_extension_multiple;
 
-      ArrayList<String> extensionsList = new ArrayList<>(validExtensions);
-      Collections.sort(extensionsList);
-
-      message = context.getString(messageId, extension, join(", ", extensionsList));
+      message = context.getString(messageId, extension,
+              setToSortedDelimitedString(validExtensions));
     }
 
     new AlertDialog.Builder(context, R.style.DolphinDialogBase)
@@ -148,13 +122,22 @@ public final class FileBrowserHelper
   }
 
   @Nullable
-  private static String getExtension(@Nullable String fileName)
+  public static String getExtension(@Nullable String fileName, boolean includeDot)
   {
     if (fileName == null)
       return null;
 
     int dotIndex = fileName.lastIndexOf(".");
-    return dotIndex != -1 ? fileName.substring(dotIndex + 1) : null;
+    if (dotIndex == -1)
+      return null;
+    return fileName.substring(dotIndex + (includeDot ? 0 : 1));
+  }
+
+  public static String setToSortedDelimitedString(Set<String> set)
+  {
+    ArrayList<String> list = new ArrayList<>(set);
+    Collections.sort(list);
+    return join(", ", list);
   }
 
   // TODO: Replace this with String.join once we can use Java 8

Source/Android/app/src/main/res/values/strings.xml

@@ -438,6 +438,7 @@ It can efficiently compress both junk data and encrypted Wii data.
     <string name="no_file_extension">The selected file does not appear to have a file name extension.\n\nContinue anyway?</string>
     <string name="wrong_file_extension_single">The selected file has the file name extension \"%1$s\", but \"%2$s\" was expected.\n\nContinue anyway?</string>
     <string name="wrong_file_extension_multiple">The selected file has the file name extension \"%1$s\", but one of these extensions was expected: %2$s\n\nContinue anyway?</string>
+    <string name="wrong_file_extension_in_directory">No compatible files were found in the selected location.\n\nThe supported formats are: %1$s</string>
     <string name="unavailable_paths">Dolphin does not have permission to access one or more configured paths. Would you like to fix this before starting?</string>
 
     <!-- Misc -->

Source/Android/jni/AndroidCommon/AndroidCommon.cpp

@@ -4,6 +4,7 @@
 
 #include "jni/AndroidCommon/AndroidCommon.h"
 
+#include <ios>
 #include <string>
 #include <string_view>
 #include <vector>
@@ -43,6 +44,14 @@ std::vector<std::string> JStringArrayToVector(JNIEnv* env, jobjectArray array)
   return result;
 }
 
+jobjectArray JStringArrayFromVector(JNIEnv* env, std::vector<std::string> vector)
+{
+  jobjectArray result = env->NewObjectArray(vector.size(), IDCache::GetStringClass(), nullptr);
+  for (jsize i = 0; i < vector.size(); ++i)
+    env->SetObjectArrayElement(result, i, ToJString(env, vector[i]));
+  return result;
+}
+
 bool IsPathAndroidContent(const std::string& uri)
 {
   return StringBeginsWith(uri, "content://");
@@ -66,6 +75,28 @@ std::string OpenModeToAndroid(std::string mode)
   return mode;
 }
 
+std::string OpenModeToAndroid(std::ios_base::openmode mode)
+{
+  std::string result;
+
+  if (mode & std::ios_base::in)
+    result += 'r';
+
+  if (mode & (std::ios_base::out | std::ios_base::app))
+    result += 'w';
+
+  if (mode & std::ios_base::app)
+    result += 'a';
+
+  constexpr std::ios_base::openmode t = std::ios_base::in | std::ios_base::trunc;
+  if ((mode & t) == t)
+    result += 't';
+
+  // The 'b' specifier is not supported. Since we're on POSIX, it's fine to just skip it.
+
+  return result;
+}
+
 int OpenAndroidContent(const std::string& uri, const std::string& mode)
 {
   JNIEnv* env = IDCache::GetEnvForThread();
@@ -81,6 +112,43 @@ bool DeleteAndroidContent(const std::string& uri)
                                       IDCache::GetContentHandlerDelete(), ToJString(env, uri));
 }
 
+jlong GetAndroidContentSizeAndIsDirectory(const std::string& uri)
+{
+  JNIEnv* env = IDCache::GetEnvForThread();
+  return env->CallStaticLongMethod(IDCache::GetContentHandlerClass(),
+                                   IDCache::GetContentHandlerGetSizeAndIsDirectory(),
+                                   ToJString(env, uri));
+}
+
+std::string GetAndroidContentDisplayName(const std::string& uri)
+{
+  JNIEnv* env = IDCache::GetEnvForThread();
+  jobject display_name =
+      env->CallStaticObjectMethod(IDCache::GetContentHandlerClass(),
+                                  IDCache::GetContentHandlerGetDisplayName(), ToJString(env, uri));
+  return display_name ? GetJString(env, reinterpret_cast<jstring>(display_name)) : "";
+}
+
+std::vector<std::string> GetAndroidContentChildNames(const std::string& uri)
+{
+  JNIEnv* env = IDCache::GetEnvForThread();
+  jobject children = env->CallStaticObjectMethod(IDCache::GetContentHandlerClass(),
+                                                 IDCache::GetContentHandlerGetChildNames(),
+                                                 ToJString(env, uri), false);
+  return JStringArrayToVector(env, reinterpret_cast<jobjectArray>(children));
+}
+
+std::vector<std::string> DoFileSearchAndroidContent(const std::string& directory,
+                                                    const std::vector<std::string>& extensions,
+                                                    bool recursive)
+{
+  JNIEnv* env = IDCache::GetEnvForThread();
+  jobject result = env->CallStaticObjectMethod(
+      IDCache::GetContentHandlerClass(), IDCache::GetContentHandlerDoFileSearch(),
+      ToJString(env, directory), JStringArrayFromVector(env, extensions), recursive);
+  return JStringArrayToVector(env, reinterpret_cast<jobjectArray>(result));
+}
+
 int GetNetworkIpAddress()
 {
   JNIEnv* env = IDCache::GetEnvForThread();

Source/Android/jni/AndroidCommon/AndroidCommon.h

@@ -4,7 +4,9 @@
 
 #pragma once
 
+#include <ios>
 #include <string>
+#include <vector>
 
 #include <jni.h>
 
@@ -17,12 +19,29 @@ bool IsPathAndroidContent(const std::string& uri);
 
 // Turns a C/C++ style mode (e.g. "rb") into one which can be used with OpenAndroidContent.
 std::string OpenModeToAndroid(std::string mode);
+std::string OpenModeToAndroid(std::ios_base::openmode mode);
 
 // Opens a given file and returns a file descriptor.
 int OpenAndroidContent(const std::string& uri, const std::string& mode);
 
 // Deletes a given file.
 bool DeleteAndroidContent(const std::string& uri);
+// Returns -1 if not found, -2 if directory, file size otherwise.
+jlong GetAndroidContentSizeAndIsDirectory(const std::string& uri);
+
+// An unmangled URI (one which the C++ code has not appended anything to) can't be relied on
+// to contain a file name at all. If a file name is desired, this function is the most reliable
+// way to get it, but the display name is not guaranteed to always actually be like a file name.
+// An empty string will be returned for files which do not exist.
+std::string GetAndroidContentDisplayName(const std::string& uri);
+
+// Returns the display names of all children of a directory, non-recursively.
+std::vector<std::string> GetAndroidContentChildNames(const std::string& uri);
+
+std::vector<std::string> DoFileSearchAndroidContent(const std::string& directory,
+                                                    const std::vector<std::string>& extensions,
+                                                    bool recursive);
+
 int GetNetworkIpAddress();
 int GetNetworkPrefixLength();
 int GetNetworkGateway();

Source/Android/jni/AndroidCommon/IDCache.cpp

@@ -10,6 +10,8 @@ static constexpr jint JNI_VERSION = JNI_VERSION_1_6;
 
 static JavaVM* s_java_vm;
 
+static jclass s_string_class;
+
 static jclass s_native_library_class;
 static jmethodID s_display_alert_msg;
 static jmethodID s_do_rumble;
@@ -44,6 +46,10 @@ static jmethodID s_compress_cb_run;
 static jclass s_content_handler_class;
 static jmethodID s_content_handler_open_fd;
 static jmethodID s_content_handler_delete;
+static jmethodID s_content_handler_get_size_and_is_directory;
+static jmethodID s_content_handler_get_display_name;
+static jmethodID s_content_handler_get_child_names;
+static jmethodID s_content_handler_do_file_search;
 
 static jclass s_network_helper_class;
 static jmethodID s_network_helper_get_network_ip_address;
@@ -75,6 +81,11 @@ JNIEnv* GetEnvForThread()
   return owned.env;
 }
 
+jclass GetStringClass()
+{
+  return s_string_class;
+}
+
 jclass GetNativeLibraryClass()
 {
   return s_native_library_class;
@@ -210,6 +221,26 @@ jmethodID GetContentHandlerDelete()
   return s_content_handler_delete;
 }
 
+jmethodID GetContentHandlerGetSizeAndIsDirectory()
+{
+  return s_content_handler_get_size_and_is_directory;
+}
+
+jmethodID GetContentHandlerGetDisplayName()
+{
+  return s_content_handler_get_display_name;
+}
+
+jmethodID GetContentHandlerGetChildNames()
+{
+  return s_content_handler_get_child_names;
+}
+
+jmethodID GetContentHandlerDoFileSearch()
+{
+  return s_content_handler_do_file_search;
+}
+
 jclass GetNetworkHelperClass()
 {
   return s_network_helper_class;
@@ -229,6 +260,7 @@ jmethodID GetNetworkHelperGetNetworkGateway()
 {
   return s_network_helper_get_network_gateway;
 }
+
 }  // namespace IDCache
 
 #ifdef __cplusplus
@@ -243,6 +275,9 @@ jint JNI_OnLoad(JavaVM* vm, void* reserved)
   if (vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION) != JNI_OK)
     return JNI_ERR;
 
+  const jclass string_class = env->FindClass("java/lang/String");
+  s_string_class = reinterpret_cast<jclass>(env->NewGlobalRef(string_class));
+
   const jclass native_library_class = env->FindClass("org/dolphinemu/dolphinemu/NativeLibrary");
   s_native_library_class = reinterpret_cast<jclass>(env->NewGlobalRef(native_library_class));
   s_display_alert_msg = env->GetStaticMethodID(s_native_library_class, "displayAlertMsg",
@@ -306,6 +341,15 @@ jint JNI_OnLoad(JavaVM* vm, void* reserved)
                                                      "(Ljava/lang/String;Ljava/lang/String;)I");
   s_content_handler_delete =
       env->GetStaticMethodID(s_content_handler_class, "delete", "(Ljava/lang/String;)Z");
+  s_content_handler_get_size_and_is_directory = env->GetStaticMethodID(
+      s_content_handler_class, "getSizeAndIsDirectory", "(Ljava/lang/String;)J");
+  s_content_handler_get_display_name = env->GetStaticMethodID(
+      s_content_handler_class, "getDisplayName", "(Ljava/lang/String;)Ljava/lang/String;");
+  s_content_handler_get_child_names = env->GetStaticMethodID(
+      s_content_handler_class, "getChildNames", "(Ljava/lang/String;Z)[Ljava/lang/String;");
+  s_content_handler_do_file_search =
+      env->GetStaticMethodID(s_content_handler_class, "doFileSearch",
+                             "(Ljava/lang/String;[Ljava/lang/String;Z)[Ljava/lang/String;");
 
   const jclass network_helper_class =
       env->FindClass("org/dolphinemu/dolphinemu/utils/NetworkHelper");

Source/Android/jni/AndroidCommon/IDCache.h

@@ -10,6 +10,8 @@ namespace IDCache
 {
 JNIEnv* GetEnvForThread();
 
+jclass GetStringClass();
+
 jclass GetNativeLibraryClass();
 jmethodID GetDisplayAlertMsg();
 jmethodID GetDoRumble();
@@ -44,6 +46,10 @@ jmethodID GetCompressCallbackRun();
 jclass GetContentHandlerClass();
 jmethodID GetContentHandlerOpenFd();
 jmethodID GetContentHandlerDelete();
+jmethodID GetContentHandlerGetSizeAndIsDirectory();
+jmethodID GetContentHandlerGetDisplayName();
+jmethodID GetContentHandlerGetChildNames();
+jmethodID GetContentHandlerDoFileSearch();
 
 jclass GetNetworkHelperClass();
 jmethodID GetNetworkHelperGetNetworkIpAddress();

Source/Core/Common/FileSearch.cpp

@@ -4,6 +4,7 @@
 
 #include <algorithm>
 #include <functional>
+#include <iterator>
 
 #include "Common/CommonPaths.h"
 #include "Common/FileSearch.h"
@@ -15,6 +16,10 @@
 namespace fs = std::filesystem;
 #define HAS_STD_FILESYSTEM
 #else
+#ifdef ANDROID
+#include "jni/AndroidCommon/AndroidCommon.h"
+#endif
+
 #include <cstring>
 #include "Common/CommonFuncs.h"
 #include "Common/FileUtil.h"
@@ -24,36 +29,30 @@ namespace Common
 {
 #ifndef HAS_STD_FILESYSTEM
 
-static std::vector<std::string>
-FileSearchWithTest(const std::vector<std::string>& directories, bool recursive,
+static void FileSearchWithTest(const std::string& directory, bool recursive,
+                               std::vector<std::string>* result_out,
                                std::function<bool(const File::FSTEntry&)> callback)
 {
-  std::vector<std::string> result;
-  for (const std::string& directory : directories)
-  {
   File::FSTEntry top = File::ScanDirectoryTree(directory, recursive);
 
-    std::function<void(File::FSTEntry&)> DoEntry;
-    DoEntry = [&](File::FSTEntry& entry) {
+  const std::function<void(File::FSTEntry&)> DoEntry = [&](File::FSTEntry& entry) {
     if (callback(entry))
-        result.push_back(entry.physicalName);
+      result_out->push_back(entry.physicalName);
     for (auto& child : entry.children)
       DoEntry(child);
   };
+
   for (auto& child : top.children)
     DoEntry(child);
-  }
-  // remove duplicates
-  std::sort(result.begin(), result.end());
-  result.erase(std::unique(result.begin(), result.end()), result.end());
-  return result;
 }
 
 std::vector<std::string> DoFileSearch(const std::vector<std::string>& directories,
                                       const std::vector<std::string>& exts, bool recursive)
 {
+  std::vector<std::string> result;
+
   bool accept_all = exts.empty();
-  return FileSearchWithTest(directories, recursive, [&](const File::FSTEntry& entry) {
+  const auto callback = [&exts, accept_all](const File::FSTEntry& entry) {
     if (accept_all)
       return true;
     if (entry.isDirectory)
@@ -63,7 +62,34 @@ std::vector<std::string> DoFileSearch(const std::vector<std::string>& directorie
       return name.length() >= ext.length() &&
              strcasecmp(name.c_str() + name.length() - ext.length(), ext.c_str()) == 0;
     });
-  });
+  };
+
+  for (const std::string& directory : directories)
+  {
+#ifdef ANDROID
+    // While File::ScanDirectoryTree (which is called in FileSearchWithTest) does handle Android
+    // content correctly, having a specialized implementation of DoFileSearch for Android content
+    // provides a much needed performance boost. Also, this specialized implementation will be
+    // required if we in the future replace the use of File::ScanDirectoryTree with std::filesystem.
+    if (IsPathAndroidContent(directory))
+    {
+      const std::vector<std::string> partial_result =
+          DoFileSearchAndroidContent(directory, exts, recursive);
+
+      result.insert(result.end(), std::make_move_iterator(partial_result.begin()),
+                    std::make_move_iterator(partial_result.end()));
+    }
+    else
+#endif
+    {
+      FileSearchWithTest(directory, recursive, &result, callback);
+    }
+  }
+
+  // remove duplicates
+  std::sort(result.begin(), result.end());
+  result.erase(std::unique(result.begin(), result.end()), result.end());
+  return result;
 }
 
 #else

Source/Core/Common/FileUtil.cpp

@@ -78,19 +78,40 @@ FileInfo::FileInfo(const char* path) : FileInfo(std::string(path))
 #else
 FileInfo::FileInfo(const std::string& path) : FileInfo(path.c_str())
 {
+#ifdef ANDROID
+  if (IsPathAndroidContent(path))
+    AndroidContentInit(path);
+  else
+#endif
+    m_exists = stat(path.c_str(), &m_stat) == 0;
 }
 
 FileInfo::FileInfo(const char* path)
 {
+#ifdef ANDROID
+  if (IsPathAndroidContent(path))
+    AndroidContentInit(path);
+  else
+#endif
     m_exists = stat(path, &m_stat) == 0;
 }
 #endif
 
 FileInfo::FileInfo(int fd)
 {
-  m_exists = fstat(fd, &m_stat);
+  m_exists = fstat(fd, &m_stat) == 0;
 }
 
+#ifdef ANDROID
+void FileInfo::AndroidContentInit(const std::string& path)
+{
+  const jlong result = GetAndroidContentSizeAndIsDirectory(path);
+  m_exists = result != -1;
+  m_stat.st_mode = result == -2 ? S_IFDIR : S_IFREG;
+  m_stat.st_size = result >= 0 ? result : 0;
+}
+#endif
+
 bool FileInfo::Exists() const
 {
   return m_exists;
@@ -476,14 +497,47 @@ FSTEntry ScanDirectoryTree(const std::string& directory, bool recursive)
   {
     const std::string virtual_name(TStrToUTF8(ffd.cFileName));
 #else
-  DIR* dirp = opendir(directory.c_str());
+  DIR* dirp = nullptr;
+
+#ifdef ANDROID
+  std::vector<std::string> child_names;
+  if (IsPathAndroidContent(directory))
+  {
+    child_names = GetAndroidContentChildNames(directory);
+  }
+  else
+#endif
+  {
+    dirp = opendir(directory.c_str());
     if (!dirp)
       return parent_entry;
+  }
+
+#ifdef ANDROID
+  auto it = child_names.cbegin();
+#endif
 
   // non Windows loop
-  while (dirent* result = readdir(dirp))
+  while (true)
   {
-    const std::string virtual_name(result->d_name);
+    std::string virtual_name;
+
+#ifdef ANDROID
+    if (!dirp)
+    {
+      if (it == child_names.cend())
+        break;
+      virtual_name = *it;
+      ++it;
+    }
+    else
+#endif
+    {
+      dirent* result = readdir(dirp);
+      if (!result)
+        break;
+      virtual_name = result->d_name;
+    }
 #endif
     if (virtual_name == "." || virtual_name == "..")
       continue;
@@ -514,6 +568,7 @@ FSTEntry ScanDirectoryTree(const std::string& directory, bool recursive)
   FindClose(hFind);
 #else
   }
+  if (dirp)
     closedir(dirp);
 #endif
 

Source/Core/Common/FileUtil.h

@@ -18,6 +18,11 @@
 #include "Common/StringUtil.h"
 #endif
 
+#ifdef ANDROID
+#include "Common/StringUtil.h"
+#include "jni/AndroidCommon/AndroidCommon.h"
+#endif
+
 // User directory indices for GetUserPath
 enum
 {
@@ -109,6 +114,10 @@ public:
   u64 GetSize() const;
 
 private:
+#ifdef ANDROID
+  void AndroidContentInit(const std::string& path);
+#endif
+
   struct stat m_stat;
   bool m_exists;
 };
@@ -214,13 +223,19 @@ std::string GetExeDirectory();
 bool WriteStringToFile(const std::string& filename, std::string_view str);
 bool ReadFileToString(const std::string& filename, std::string& str);
 
-// To deal with Windows being dumb at unicode:
+// To deal with Windows not fully supporting UTF-8 and Android not fully supporting paths.
 template <typename T>
 void OpenFStream(T& fstream, const std::string& filename, std::ios_base::openmode openmode)
 {
 #ifdef _WIN32
   fstream.open(UTF8ToTStr(filename).c_str(), openmode);
 #else
+#ifdef ANDROID
+  // Unfortunately it seems like the non-standard __open is the only way to use a file descriptor
+  if (IsPathAndroidContent(filename))
+    fstream.__open(OpenAndroidContent(filename, OpenModeToAndroid(openmode)), openmode);
+  else
+#endif
     fstream.open(filename.c_str(), openmode);
 #endif
 }

Source/Core/Core/Boot/Boot.cpp

@@ -158,6 +158,15 @@ BootParameters::GenerateFromFile(std::vector<std::string> paths,
   if (paths.size() == 1)
     paths.clear();
 
+#ifdef ANDROID
+  if (extension.empty() && IsPathAndroidContent(path))
+  {
+    const std::string display_name = GetAndroidContentDisplayName(path);
+    SplitPath(display_name, nullptr, nullptr, &extension);
+    std::transform(extension.begin(), extension.end(), extension.begin(), ::tolower);
+  }
+#endif
+
   static const std::unordered_set<std::string> disc_image_extensions = {
       {".gcm", ".iso", ".tgc", ".wbfs", ".ciso", ".gcz", ".wia", ".rvz", ".dol", ".elf"}};
   if (disc_image_extensions.find(extension) != disc_image_extensions.end() || is_drive)