Add directory selection to DocumentsProvider.

Introduce new ACTION_PICK_DIRECTORY that allows users to grant access
to an entire document subtree.  Instead of requiring grants for each
individual document, this leverages new prefix URI permission grants
by defining new "via"-style URIs:

content://com.example/via/12/document/24/

This references document 24 by using a prefix grant given for
document 12.  Internally, we use isChildDocument() to enforce that
24 is actually a descendant (child, grandchild, etc) of 12.  Since
this is an optional API, providers indicate support with
Root.FLAG_SUPPORTS_DIR_SELECTION.

Extend DocumentsUI to support picking directories.  Expose
createDocument() API to work with returned directories.

Offer to canonicalize via-style URIs into direct URIs, generating
exact permission grants along the way.  Override openAssetFile()
to pass through CancellationSignal.  Move testing code into ApiDemos.

Bug: 10607375
Change-Id: Ifffc1cff878870f8152eb6ca0199c5d014b9cb07

1 files changed, 20 insertions, 3 deletions

diff --git a/packages/ExternalStorageProvider/src/com/android/externalstorage/ExternalStorageProvider.java b/packages/ExternalStorageProvider/src/com/android/externalstorage/ExternalStorageProvider.java
index 559e052..16fc3e5 100644
--- a/packages/ExternalStorageProvider/src/com/android/externalstorage/ExternalStorageProvider.java
+++ b/packages/ExternalStorageProvider/src/com/android/externalstorage/ExternalStorageProvider.java
@@ -27,6 +27,7 @@ import android.net.Uri;
 import android.os.CancellationSignal;
 import android.os.Environment;
 import android.os.FileObserver;
+import android.os.FileUtils;
 import android.os.ParcelFileDescriptor;
 import android.os.storage.StorageManager;
 import android.os.storage.StorageVolume;
@@ -143,7 +144,7 @@ public class ExternalStorageProvider extends DocumentsProvider {
                 final RootInfo root = new RootInfo();
                 root.rootId = rootId;
                 root.flags = Root.FLAG_SUPPORTS_CREATE | Root.FLAG_LOCAL_ONLY | Root.FLAG_ADVANCED
-                        | Root.FLAG_SUPPORTS_SEARCH;
+                        | Root.FLAG_SUPPORTS_SEARCH | Root.FLAG_SUPPORTS_DIR_SELECTION;
                 if (ROOT_ID_PRIMARY_EMULATED.equals(rootId)) {
                     root.title = getContext().getString(R.string.root_internal_storage);
                 } else {
@@ -240,8 +241,8 @@ public class ExternalStorageProvider extends DocumentsProvider {
                 flags |= Document.FLAG_DIR_SUPPORTS_CREATE;
             } else {
                 flags |= Document.FLAG_SUPPORTS_WRITE;
+                flags |= Document.FLAG_SUPPORTS_DELETE;
             }
-            flags |= Document.FLAG_SUPPORTS_DELETE;
         }
 
         final String displayName = file.getName();
@@ -284,11 +285,26 @@ public class ExternalStorageProvider extends DocumentsProvider {
     }
 
     @Override
+    public boolean isChildDocument(String parentDocId, String docId) {
+        try {
+            final File parent = getFileForDocId(parentDocId).getCanonicalFile();
+            final File doc = getFileForDocId(docId).getCanonicalFile();
+            return FileUtils.contains(parent, doc);
+        } catch (IOException e) {
+            throw new IllegalArgumentException(
+                    "Failed to determine if " + docId + " is child of " + parentDocId + ": " + e);
+        }
+    }
+
+    @Override
     public String createDocument(String docId, String mimeType, String displayName)
             throws FileNotFoundException {
         final File parent = getFileForDocId(docId);
-        File file;
+        if (!parent.isDirectory()) {
+            throw new IllegalArgumentException("Parent document isn't a directory");
+        }
 
+        File file;
         if (Document.MIME_TYPE_DIR.equals(mimeType)) {
             file = new File(parent, displayName);
             if (!file.mkdir()) {
@@ -317,6 +333,7 @@ public class ExternalStorageProvider extends DocumentsProvider {
 
     @Override
     public void deleteDocument(String docId) throws FileNotFoundException {
+        // TODO: extend to delete directories
         final File file = getFileForDocId(docId);
         if (!file.delete()) {
             throw new IllegalStateException("Failed to delete " + file);