fail with warning if we get data from the AOSP mail client (see #290)

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/DecryptActivity.java

@@ -159,7 +159,17 @@ public class DecryptActivity extends BaseActivity {
                     canDelete = true;
                 case OpenKeychainIntents.DECRYPT_DATA:
                 default:
-                    uris.add(intent.getData());
+                    Uri uri = intent.getData();
+                    if (uri != null) {
+
+                        if ("com.android.email.attachmentprovider".equals(uri.getHost())) {
+                            Toast.makeText(this, R.string.error_reading_aosp, Toast.LENGTH_LONG).show();
+                            finish();
+                            return;
+                        }
+
+                        uris.add(intent.getData());
+                    }
 
             }
 

OpenKeychain/src/main/res/values/strings.xml

@@ -1540,6 +1540,7 @@
     <string name="error_loading_keys">"Error loading keys!"</string>
     <string name="error_empty_log">"(error, empty log)"</string>
     <string name="error_reading_text">"Could not read input to decrypt!"</string>
+    <string name="error_reading_aosp">"Failed reading data, this is a bug in the Android E-Mail client!"</string>
     <string name="filename_unknown">Unknown filename (click to open)</string>
     <string name="filename_unknown_text">Text (click to show)</string>
     <string name="intent_show">Show Signed/Encrypted Content</string>