From 2ca39c020f17e0815626df0fec417bacda2dc837 Mon Sep 17 00:00:00 2001
From: Manish Singh <psych@google.com>
Date: Mon, 1 Feb 2021 21:36:59 +0000
Subject: [PATCH] Pass the media capabilities uid when opening media

FileSystemProvider should pass the uid of the calling app by setting
the EXTRA_MEDIA_CAPABILITIES_UID when opening a media, so that
TranscodeHelper can make decision to transcode or not transcode based on
the calling uid, and not based upon the Provider's uid.

BUG=176157500
Test: manual testing.

Change-Id: Ie08b94cf79c86e9f87639e4fbdd82b2732771187
---
 .../internal/content/FileSystemProvider.java  | 21 ++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/core/java/com/android/internal/content/FileSystemProvider.java b/core/java/com/android/internal/content/FileSystemProvider.java
index 0ede1b86b524d..e602cd2c8890e 100644
--- a/core/java/com/android/internal/content/FileSystemProvider.java
+++ b/core/java/com/android/internal/content/FileSystemProvider.java
@@ -28,6 +28,7 @@ import android.database.MatrixCursor;
 import android.database.MatrixCursor.RowBuilder;
 import android.graphics.Point;
 import android.net.Uri;
+import android.os.Binder;
 import android.os.Bundle;
 import android.os.CancellationSignal;
 import android.os.FileObserver;
@@ -504,7 +505,7 @@ public abstract class FileSystemProvider extends DocumentsProvider {
 
         final int pfdMode = ParcelFileDescriptor.parseMode(mode);
         if (pfdMode == ParcelFileDescriptor.MODE_READ_ONLY || visibleFile == null) {
-            return ParcelFileDescriptor.open(file, pfdMode);
+            return openFileForRead(file);
         } else {
             try {
                 // When finished writing, kick off media scanner
@@ -519,6 +520,24 @@ public abstract class FileSystemProvider extends DocumentsProvider {
         }
     }
 
+    private ParcelFileDescriptor openFileForRead(final File target) throws FileNotFoundException {
+        final Uri uri = MediaStore.scanFile(getContext().getContentResolver(), target);
+
+        // Passing the calling uid via EXTRA_MEDIA_CAPABILITIES_UID, so that the decision to
+        // transcode or not transcode can be made based upon the calling app's uid, and not based
+        // upon the Provider's uid.
+        final Bundle opts = new Bundle();
+        opts.putInt(MediaStore.EXTRA_MEDIA_CAPABILITIES_UID, Binder.getCallingUid());
+
+        final AssetFileDescriptor afd =
+                getContext().getContentResolver().openTypedAssetFileDescriptor(uri, "*/*", opts);
+        if (afd == null) {
+            return null;
+        }
+
+        return afd.getParcelFileDescriptor();
+    }
+
     /**
      * Test if the file matches the query arguments.
      *