ole32: Return END_OF_CHAIN for chains starting with special sector values.

dlls/ole32/storage32.c

@@ -6995,11 +6995,9 @@ static ULONG BlockChainStream_GetHeadOfChain(BlockChainStream* This)
                       This->ownerDirEntry,
                       &chainEntry);
 
-    if (SUCCEEDED(hr))
-    {
+    if (SUCCEEDED(hr) && chainEntry.startingBlock < BLOCK_FIRST_SPECIAL)
       return chainEntry.startingBlock;
   }
-  }
 
   return BLOCK_END_OF_CHAIN;
 }
@@ -7520,13 +7518,10 @@ static ULONG SmallBlockChainStream_GetHeadOfChain(
                       This->ownerDirEntry,
                       &chainEntry);
 
-    if (SUCCEEDED(hr))
-    {
+    if (SUCCEEDED(hr) && chainEntry.startingBlock < BLOCK_FIRST_SPECIAL)
       return chainEntry.startingBlock;
   }
 
-  }
-
   return BLOCK_END_OF_CHAIN;
 }
 

dlls/ole32/storage32.h

@@ -78,6 +78,7 @@ static const WORD  MAX_BIG_BLOCK_SIZE_BITS   = 0x000c;
 static const WORD  DEF_SMALL_BLOCK_SIZE_BITS = 0x0006;
 static const WORD  DEF_BIG_BLOCK_SIZE        = 0x0200;
 static const WORD  DEF_SMALL_BLOCK_SIZE      = 0x0040;
+static const ULONG BLOCK_FIRST_SPECIAL       = 0xFFFFFFFB;
 static const ULONG BLOCK_EXTBBDEPOT          = 0xFFFFFFFC;
 static const ULONG BLOCK_SPECIAL             = 0xFFFFFFFD;
 static const ULONG BLOCK_END_OF_CHAIN        = 0xFFFFFFFE;