[Android] Check for text to paste before trying to retrieve data from URI

shell/platform/android/io/flutter/plugin/platform/PlatformPlugin.java

@@ -11,6 +11,7 @@
 import android.content.ClipDescription;
 import android.content.ClipboardManager;
 import android.content.Context;
+import android.net.Uri;
 import android.os.Build;
 import android.view.HapticFeedbackConstants;
 import android.view.SoundEffectConstants;
@@ -517,8 +518,27 @@ private CharSequence getClipboardData(PlatformChannel.ClipboardContentFormat for
       if (clip == null) return null;
       if (format == null || format == PlatformChannel.ClipboardContentFormat.PLAIN_TEXT) {
         ClipData.Item item = clip.getItemAt(0);
-        if (item.getUri() != null)
-          activity.getContentResolver().openTypedAssetFileDescriptor(item.getUri(), "text/*", null);
+        // First, try getting clipboard data as text; no further processing
+        // required if so.
+        CharSequence itemText = item.getText();
+
+        if (itemText == null) {
+          // Clipboard data does not contain text, so check whether or not it
+          // contains a URI to extract text from.
+          Uri itemUri = item.getUri();
+
+          if (itemUri == null) {
+            Log.w(
+                TAG, "Clipboard item contained no textual content nor a URI to retrieve it from.");
+            return null;
+          } else if (!canExtractTextFromUri(itemUri)) {
+            Log.w(TAG, "Clipboard text was unable to be received from content URI.");
+            return null;
+          }
+        }
+
+        // Safely return clipboard data coerced into text; will return either
+        // itemText or text retrieved from its URI.
         return item.coerceToText(activity);
       }
     } catch (SecurityException e) {
@@ -529,13 +549,30 @@ private CharSequence getClipboardData(PlatformChannel.ClipboardContentFormat for
               + "https://developer.android.com/guide/topics/permissions/overview",
           e);
       return null;
-    } catch (FileNotFoundException e) {
-      return null;
     }
 
     return null;
   }
 
+  private boolean canExtractTextFromUri(Uri uri) {
+    // Will only try to extract text from URI if it has the content scheme.
+    String uriScheme = uri.getScheme();
+
+    if (!uriScheme.equals("content")) {
+      Log.w(TAG, "Clipboard item contains a Uri with scheme '" + uriScheme + "'that is unhandled.");
+      return false;
+    }
+
+    try {
+      activity.getContentResolver().openTypedAssetFileDescriptor(uri, "text/*", null);
+    } catch (FileNotFoundException e) {
+      return false;
+    }
+
+    // Text can successfully be extracted from content URI.
+    return true;
+  }
+
   private void setClipboardData(String text) {
     ClipboardManager clipboard =
         (ClipboardManager) activity.getSystemService(Context.CLIPBOARD_SERVICE);