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app/src/main/java/org/thoughtcrime/securesms/util/MemoryFileDescriptorProxy.java

@@ -0,0 +1,89 @@
+package org.thoughtcrime.securesms.util;
+
+import android.content.Context;
+import android.os.Handler;
+import android.os.HandlerThread;
+import android.os.MemoryFile;
+import android.os.ParcelFileDescriptor;
+import android.os.ProxyFileDescriptorCallback;
+import android.os.storage.StorageManager;
+import android.system.ErrnoException;
+import android.system.OsConstants;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.RequiresApi;
+
+import org.thoughtcrime.securesms.logging.Log;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Objects;
+
+@RequiresApi(api = 26)
+final class MemoryFileDescriptorProxy {
+
+  private static final String TAG = Log.tag(MemoryFileDescriptorProxy.class);
+
+  public static ParcelFileDescriptor create(@NonNull Context context,
+                                            @NonNull MemoryFile file)
+      throws IOException
+  {
+    StorageManager storageManager = Objects.requireNonNull(context.getSystemService(StorageManager.class));
+    HandlerThread  thread         = new HandlerThread("MemoryFile");
+
+    thread.start();
+    Log.i(TAG, "Thread started");
+
+    Handler       handler       = new Handler(thread.getLooper());
+    ProxyCallback proxyCallback = new ProxyCallback(file, () -> {
+      if (thread.quitSafely()) {
+        Log.i(TAG, "Thread quitSafely true");
+      } else {
+        Log.w(TAG, "Thread quitSafely false");
+      }
+    });
+
+    ParcelFileDescriptor parcelFileDescriptor = storageManager.openProxyFileDescriptor(ParcelFileDescriptor.MODE_READ_ONLY,
+                                                                                       proxyCallback,
+                                                                                       handler);
+
+    Log.i(TAG, "Created");
+    return parcelFileDescriptor;
+  }
+
+  private static final class ProxyCallback extends ProxyFileDescriptorCallback {
+
+    private final MemoryFile memoryFile;
+    private final Runnable   onClose;
+
+    ProxyCallback(@NonNull MemoryFile memoryFile, Runnable onClose) {
+      this.memoryFile = memoryFile;
+      this.onClose    = onClose;
+    }
+
+    @Override
+    public long onGetSize() {
+      return memoryFile.length();
+    }
+
+    @Override
+    public int onRead(long offset, int size, byte[] data) throws ErrnoException {
+      try {
+        InputStream inputStream = memoryFile.getInputStream();
+        if(inputStream.skip(offset) != offset){
+          throw new AssertionError();
+        }
+        return inputStream.read(data, 0, size);
+      } catch (IOException e) {
+        throw new ErrnoException("onRead", OsConstants.EBADF);
+      }
+    }
+
+    @Override
+    public void onRelease() {
+      Log.i(TAG, "onRelease()");
+      memoryFile.close();
+      onClose.run();
+    }
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/util/MemoryFileUtil.java

@@ -1,36 +1,50 @@
 package org.thoughtcrime.securesms.util;
 
-
+import android.annotation.SuppressLint;
 import android.os.Build;
 import android.os.MemoryFile;
 import android.os.ParcelFileDescriptor;
 
+import androidx.annotation.NonNull;
+
+import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
+
 import java.io.FileDescriptor;
 import java.io.IOException;
 import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 
-public class MemoryFileUtil {
+public final class MemoryFileUtil {
 
-  public static ParcelFileDescriptor getParcelFileDescriptor(MemoryFile file) throws IOException {
+  private MemoryFileUtil() {}
+
+  public static ParcelFileDescriptor getParcelFileDescriptor(@NonNull MemoryFile file)
+      throws IOException
+  {
+    if (Build.VERSION.SDK_INT >= 26) {
+      return MemoryFileDescriptorProxy.create(ApplicationDependencies.getApplication(), file);
+    } else {
+      return getParcelFileDescriptorLegacy(file);
+    }
+  }
+
+  @SuppressWarnings("JavaReflectionMemberAccess")
+  @SuppressLint("PrivateApi")
+  public static ParcelFileDescriptor getParcelFileDescriptorLegacy(@NonNull MemoryFile file)
+      throws IOException
+  {
     try {
       Method         method         = MemoryFile.class.getDeclaredMethod("getFileDescriptor");
       FileDescriptor fileDescriptor = (FileDescriptor) method.invoke(file);
 
-      Field  field  = fileDescriptor.getClass().getDeclaredField("descriptor");
+      Field field = fileDescriptor.getClass().getDeclaredField("descriptor");
       field.setAccessible(true);
 
       int fd = field.getInt(fileDescriptor);
 
       return ParcelFileDescriptor.adoptFd(fd);
-    } catch (IllegalAccessException e) {
-      throw new IOException(e);
-    } catch (InvocationTargetException e) {
-      throw new IOException(e);
-    } catch (NoSuchMethodException e) {
-      throw new IOException(e);
-    } catch (NoSuchFieldException e) {
+    } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException | NoSuchFieldException e) {
       throw new IOException(e);
     }
   }