From 05de74702aa511e67c0a8066522f04b566ae4844 Mon Sep 17 00:00:00 2001
From: Aleksey Bragin <aleksey@reactos.org>
Date: Wed, 9 Feb 2011 20:42:44 +0000
Subject: [PATCH] - Robert Horvath: LocalUnlock has to be different from
 GlobalUnlock. The subtle difference between LocalUnlock and GlobalUnlock, is,
 that the former will return FALSE and set ERROR_NOT_LOCKED on LMEM_FIXED
 allocations. Fixes 1 kernel32:heap failure. See issue #5869 for more details.

svn path=/trunk/; revision=50637
---
 reactos/dll/win32/kernel32/mem/local.c | 58 +++++++++++++++++++++++++-
 1 file changed, 56 insertions(+), 2 deletions(-)

diff --git a/reactos/dll/win32/kernel32/mem/local.c b/reactos/dll/win32/kernel32/mem/local.c
index 68d9de20699..875ae4bce8a 100644
--- a/reactos/dll/win32/kernel32/mem/local.c
+++ b/reactos/dll/win32/kernel32/mem/local.c
@@ -441,8 +441,62 @@ BOOL
 NTAPI
 LocalUnlock(HLOCAL hMem)
 {
-    /* This is the same as a Global Unlock */
-    return GlobalUnlock(hMem);
+    PBASE_HEAP_HANDLE_ENTRY HandleEntry;
+    BOOL RetVal = TRUE;
+
+    /* Check if this was a simple allocated heap entry */
+    if (!((ULONG_PTR)hMem & BASE_HEAP_IS_HANDLE_ENTRY))
+    {
+       /* Fail, because LocalUnlock is not supported on LMEM_FIXED allocations */
+       SetLastError(ERROR_NOT_LOCKED);
+       return FALSE;
+    }
+
+    /* Otherwise, lock the heap */
+    RtlLockHeap(hProcessHeap);
+
+    /* Get the handle entry */
+    HandleEntry = BaseHeapGetEntry(hMem);
+    BASE_TRACE_HANDLE(HandleEntry, hMem);
+
+    _SEH2_TRY
+    {
+        /* Make sure it's valid */
+        if (!BaseHeapValidateEntry(HandleEntry))
+        {
+            /* It's not, fail */
+            BASE_TRACE_FAILURE();
+            SetLastError(ERROR_INVALID_HANDLE);
+            RetVal = FALSE;
+        }
+        else
+        {
+            /* Otherwise, decrement lock count, unless we're already at 0*/
+            if (!HandleEntry->LockCount--)
+            {
+                /* In which case we simply lock it back and fail */
+                HandleEntry->LockCount++;
+                SetLastError(ERROR_NOT_LOCKED);
+                RetVal = FALSE;
+            }
+            else if (!HandleEntry->LockCount)
+            {
+                /* Nothing to unlock */
+                SetLastError(NO_ERROR);
+                RetVal = FALSE;
+            }
+        }
+    }
+    _SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
+    {
+        SetLastError(ERROR_INVALID_PARAMETER);
+        RetVal = FALSE;
+    }
+    _SEH2_END
+
+    /* All done. Unlock the heap and return the pointer */
+    RtlUnlockHeap(hProcessHeap);
+    return RetVal;
 }
 
 /* EOF */