Fix backwards compat problem with AAPT public attrs

AAPT has traditionally assigned resource IDs to public attributes,
and then followed those public definitions with private attributes.

--- PUBLIC ---
| 0x01010234 | attr/color
| 0x01010235 | attr/background

--- PRIVATE ---
| 0x01010236 | attr/secret
| 0x01010237 | attr/shhh

Each release, when attributes are added, they take the place of the private
attributes and the private attributes are shifted down again.

--- PUBLIC ---
| 0x01010234 | attr/color
| 0x01010235 | attr/background
| 0x01010236 | attr/shinyNewAttr
| 0x01010237 | attr/highlyValuedFeature

--- PRIVATE ---
| 0x01010238 | attr/secret
| 0x01010239 | attr/shhh

Platform code may look for private attributes set in a theme. If an app
compiled against a newer version of the platform uses a new public
attribute that happens to have the same ID as the private attribute
the older platform is expecting, then the behavior is undefined.

We get around this by detecting any newly defined attributes (in L),
copy the resource into a -v21 qualified resource, and delete the
attribute from the original resource. This ensures that older platforms
don't see the new attribute, but when running on L+ platforms, the
attribute will be respected.

We still need to address this problem in the platform moving forward,
as this will only help us in the transition from pre L to L.

Bug:17520380
Change-Id: Ia2a985798b50006c21c7c3431d30d9598f27cd91

1 files changed, 8 insertions, 0 deletions

diff --git a/tools/aapt/ResourceTable.h b/tools/aapt/ResourceTable.h
index 3721de4..025a868 100644
--- a/tools/aapt/ResourceTable.h
+++ b/tools/aapt/ResourceTable.h
@@ -165,6 +165,8 @@ public:
     size_t numLocalResources() const;
     bool hasResources() const;
 
+    status_t modifyForCompat(const Bundle* bundle);
+
     sp<AaptFile> flatten(Bundle* bundle, const sp<const ResourceFilter>& filter,
             const bool isBase);
 
@@ -281,6 +283,9 @@ public:
             : mName(name), mType(TYPE_UNKNOWN),
               mItemFormat(ResTable_map::TYPE_ANY), mNameIndex(-1), mPos(pos)
         { }
+
+        Entry(const Entry& entry);
+
         virtual ~Entry() { }
 
         enum type {
@@ -311,6 +316,8 @@ public:
                           bool replace=false, bool isId = false,
                           int32_t format = ResTable_map::TYPE_ANY);
 
+        status_t removeFromBag(const String16& key);
+
         // Index of the entry's name string in the key pool.
         int32_t getNameIndex() const { return mNameIndex; }
         void setNameIndex(int32_t index) { mNameIndex = index; }
@@ -523,6 +530,7 @@ private:
     const Item* getItem(uint32_t resID, uint32_t attrID) const;
     bool getItemValue(uint32_t resID, uint32_t attrID,
                       Res_value* outValue);
+    bool isAttributeFromL(uint32_t attrId);
 
 
     String16 mAssetsPackage;