From e05b8416b846790a2b3ec82ba69282e9724d581d Mon Sep 17 00:00:00 2001
From: Vincent Povirk <vincent@codeweavers.com>
Date: Sat, 20 Mar 2010 13:13:47 -0500
Subject: [PATCH] ole32: Track the lowest possibly-free small block in storage
 files.

This makes creating small block chains O(n) instead of O(n**2) because we
don't have to keep rechecking the first blocks in the file.
---
 dlls/ole32/storage32.c | 7 ++++++-
 dlls/ole32/storage32.h | 3 +++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/dlls/ole32/storage32.c b/dlls/ole32/storage32.c
index f1706da72fb..a15e3dbdd29 100644
--- a/dlls/ole32/storage32.c
+++ b/dlls/ole32/storage32.c
@@ -2711,6 +2711,8 @@ static HRESULT StorageImpl_Construct(
    */
   This->prevFreeBlock = 0;
 
+  This->firstFreeSmallBlock = 0;
+
   /*
    * Create the block chain abstractions.
    */
@@ -5710,7 +5712,7 @@ static ULONG SmallBlockChainStream_GetNextFreeBlock(
   ULARGE_INTEGER offsetOfBlockInDepot;
   DWORD buffer;
   ULONG bytesRead;
-  ULONG blockIndex = 0;
+  ULONG blockIndex = This->parentStorage->firstFreeSmallBlock;
   ULONG nextBlockIndex = BLOCK_END_OF_CHAIN;
   HRESULT res = S_OK;
   ULONG smallBlocksPerBigBlock;
@@ -5819,6 +5821,8 @@ static ULONG SmallBlockChainStream_GetNextFreeBlock(
     }
   }
 
+  This->parentStorage->firstFreeSmallBlock = blockIndex+1;
+
   smallBlocksPerBigBlock =
     This->parentStorage->bigBlockSize / This->parentStorage->smallBlockSize;
 
@@ -6117,6 +6121,7 @@ static BOOL SmallBlockChainStream_Shrink(
 							&blockIndex)))
       return FALSE;
     SmallBlockChainStream_FreeBlock(This, extraBlock);
+    This->parentStorage->firstFreeSmallBlock = min(This->parentStorage->firstFreeSmallBlock, extraBlock);
     extraBlock = blockIndex;
   }
 
diff --git a/dlls/ole32/storage32.h b/dlls/ole32/storage32.h
index fad5d7766f7..dfa5d1a98ed 100644
--- a/dlls/ole32/storage32.h
+++ b/dlls/ole32/storage32.h
@@ -360,6 +360,9 @@ struct StorageImpl
   ULONG indexBlockDepotCached;
   ULONG prevFreeBlock;
 
+  /* All small blocks before this one are known to be in use. */
+  ULONG firstFreeSmallBlock;
+
   /*
    * Abstraction of the big block chains for the chains of the header.
    */