1 files changed, 43 insertions, 3 deletions

diff --git a/core/java/android/provider/DocumentsContract.java b/core/java/android/provider/DocumentsContract.java
index acaed73..53f5d58 100644
--- a/core/java/android/provider/DocumentsContract.java
+++ b/core/java/android/provider/DocumentsContract.java
@@ -19,7 +19,9 @@ package android.provider;
 import android.content.ContentProvider;
 import android.content.ContentResolver;
 import android.content.ContentValues;
+import android.content.Context;
 import android.content.Intent;
+import android.content.pm.PackageManager;
 import android.content.pm.ProviderInfo;
 import android.content.res.AssetFileDescriptor;
 import android.database.Cursor;
@@ -30,6 +32,8 @@ import android.net.Uri;
 import android.os.Bundle;
 import android.util.Log;
 
+import com.google.android.collect.Lists;
+
 import libcore.io.IoUtils;
 
 import java.io.IOException;
@@ -201,19 +205,25 @@ public final class DocumentsContract {
 
     public static String getRootId(Uri documentUri) {
         final List<String> paths = documentUri.getPathSegments();
+        if (paths.size() < 2) {
+            throw new IllegalArgumentException("Not a root: " + documentUri);
+        }
         if (!PATH_ROOTS.equals(paths.get(0))) {
-            throw new IllegalArgumentException();
+            throw new IllegalArgumentException("Not a root: " + documentUri);
         }
         return paths.get(1);
     }
 
     public static String getDocId(Uri documentUri) {
         final List<String> paths = documentUri.getPathSegments();
+        if (paths.size() < 4) {
+            throw new IllegalArgumentException("Not a document: " + documentUri);
+        }
         if (!PATH_ROOTS.equals(paths.get(0))) {
-            throw new IllegalArgumentException();
+            throw new IllegalArgumentException("Not a document: " + documentUri);
         }
         if (!PATH_DOCS.equals(paths.get(2))) {
-            throw new IllegalArgumentException();
+            throw new IllegalArgumentException("Not a document: " + documentUri);
         }
         return paths.get(3);
     }
@@ -359,6 +369,36 @@ public final class DocumentsContract {
     }
 
     /**
+     * Return list of all documents that the calling package has "open." These
+     * are Uris matching {@link DocumentsContract} to which persistent
+     * read/write access has been granted, usually through
+     * {@link Intent#ACTION_OPEN_DOCUMENT} or
+     * {@link Intent#ACTION_CREATE_DOCUMENT}.
+     *
+     * @see Context#grantUriPermission(String, Uri, int)
+     * @see ContentResolver#getIncomingUriPermissionGrants(int, int)
+     */
+    public static Uri[] getOpenDocuments(Context context) {
+        final int openedFlags = Intent.FLAG_GRANT_READ_URI_PERMISSION
+                | Intent.FLAG_GRANT_WRITE_URI_PERMISSION | Intent.FLAG_PERSIST_GRANT_URI_PERMISSION;
+        final Uri[] uris = context.getContentResolver()
+                .getIncomingUriPermissionGrants(openedFlags, openedFlags);
+
+        // Filter to only include document providers
+        final PackageManager pm = context.getPackageManager();
+        final List<Uri> result = Lists.newArrayList();
+        for (Uri uri : uris) {
+            final ProviderInfo info = pm.resolveContentProvider(
+                    uri.getAuthority(), PackageManager.GET_META_DATA);
+            if (info.metaData.containsKey(META_DATA_DOCUMENT_PROVIDER)) {
+                result.add(uri);
+            }
+        }
+
+        return result.toArray(new Uri[result.size()]);
+    }
+
+    /**
      * Return thumbnail representing the document at the given URI. Callers are
      * responsible for their own caching. Given document must have
      * {@link #FLAG_SUPPORTS_THUMBNAIL} set.