[SettingsProvider] verify ringtone URI before setting

Similar to ag/24422287, but the same URI verification should be done in
SettingsProvider as well, which can be called by apps via
Settings.System API or ContentProvider APIs without using
RingtoneManager.

BUG: 227201030
Test: manual with a test app. Will add a CTS test.
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:1b234678ec122994ccbfc52ac48aafdad7fdb1ed)
Merged-In: Ic0ffa1db14b5660d02880b632a7f2ad9e6e5d84b
Change-Id: Ic0ffa1db14b5660d02880b632a7f2ad9e6e5d84b

Author: schfan-1

packages/SettingsProvider/src/com/android/providers/settings/SettingsProvider.java

@@ -1928,6 +1928,9 @@ private boolean mutateSystemSetting(String name, String value, int runAsUserId,
             cacheName = Settings.System.ALARM_ALERT_CACHE;
         }
         if (cacheName != null) {
+            if (!isValidAudioUri(name, value)) {
+                return false;
+            }
             final File cacheFile = new File(
                     getRingtoneCacheDir(owningUserId), cacheName);
             cacheFile.delete();
@@ -1960,6 +1963,34 @@ private boolean mutateSystemSetting(String name, String value, int runAsUserId,
         }
     }
 
+    private boolean isValidAudioUri(String name, String uri) {
+        if (uri != null) {
+            Uri audioUri = Uri.parse(uri);
+            if (Settings.AUTHORITY.equals(
+                    ContentProvider.getAuthorityWithoutUserId(audioUri.getAuthority()))) {
+                // Don't accept setting the default uri to self-referential URIs like
+                // Settings.System.DEFAULT_RINGTONE_URI, which is an alias to the value of this
+                // setting.
+                return false;
+            }
+            final String mimeType = getContext().getContentResolver().getType(audioUri);
+            if (mimeType == null) {
+                Slog.e(LOG_TAG,
+                        "mutateSystemSetting for setting: " + name + " URI: " + audioUri
+                        + " ignored: failure to find mimeType (no access from this context?)");
+                return false;
+            }
+            if (!(mimeType.startsWith("audio/") || mimeType.equals("application/ogg")
+                    || mimeType.equals("application/x-flac"))) {
+                Slog.e(LOG_TAG,
+                        "mutateSystemSetting for setting: " + name + " URI: " + audioUri
+                        + " ignored: associated mimeType: " + mimeType + " is not an audio type");
+                return false;
+            }
+        }
+        return true;
+    }
+
     private boolean hasWriteSecureSettingsPermission() {
         // Write secure settings is a more protected permission. If caller has it we are good.
         return getContext().checkCallingOrSelfPermission(Manifest.permission.WRITE_SECURE_SETTINGS)