Fix issue where non-resource attributes would cause obtainStyleAttributes to fail

A sentinal value of 0x00000000 was used to mark the first time an AttributeFinder
was used. If the resource ID of an attribute was also 0x00000000 (which occurs with
non-resource attributes, like 'style'), then it would be mistaken as the sentinel
start value.

Bug:18421787
Change-Id: I4be353e0f8c940cb6f262d155129f048dcc444ae

1 files changed, 8 insertions, 3 deletions

diff --git a/include/androidfw/AttributeFinder.h b/include/androidfw/AttributeFinder.h
index a0ffeb3..acf7056 100644
--- a/include/androidfw/AttributeFinder.h
+++ b/include/androidfw/AttributeFinder.h
@@ -64,6 +64,7 @@ private:
     void jumpToClosestAttribute(uint32_t packageId);
     void markCurrentPackageId(uint32_t packageId);
 
+    bool mFirstTime;
     Iterator mBegin;
     Iterator mEnd;
     Iterator mCurrent;
@@ -81,7 +82,8 @@ private:
 
 template <typename Derived, typename Iterator> inline
 BackTrackingAttributeFinder<Derived, Iterator>::BackTrackingAttributeFinder(const Iterator& begin, const Iterator& end)
-    : mBegin(begin)
+    : mFirstTime(true)
+    , mBegin(begin)
     , mEnd(end)
     , mCurrent(begin)
     , mLargest(begin)
@@ -145,8 +147,11 @@ Iterator BackTrackingAttributeFinder<Derived, Iterator>::find(uint32_t attr) {
         return mEnd;
     }
 
-    if (mCurrentAttr == 0) {
-        // One-time initialization.
+    if (mFirstTime) {
+        // One-time initialization. We do this here instead of the constructor
+        // because the derived class we access in getAttribute() may not be
+        // fully constructed.
+        mFirstTime = false;
         mCurrentAttr = static_cast<const Derived*>(this)->getAttribute(mBegin);
         mLastPackageId = getPackage(mCurrentAttr);
         markCurrentPackageId(mLastPackageId);