From e79310d60f417a51c914b065425d1b4b83aa3690 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Thu, 13 Sep 2007 18:42:19 +0000
Subject: [PATCH] don't interpret the first DWORD of data as its size if there
 is nothing following it (this fixes bug 1791459 for the 2.8 branch)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@48663 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 src/msw/ole/dataobj.cpp | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/src/msw/ole/dataobj.cpp b/src/msw/ole/dataobj.cpp
index 4cfcee5e9e..d23ae6fa6b 100644
--- a/src/msw/ole/dataobj.cpp
+++ b/src/msw/ole/dataobj.cpp
@@ -685,13 +685,14 @@ size_t wxDataObject::GetBufferOffset(const wxDataFormat& format )
     return NeedsVerbatimData(format) ? 0 : sizeof(size_t);
 }
 
-const void* wxDataObject::GetSizeFromBuffer( const void* buffer, size_t* size,
-                                               const wxDataFormat& format )
+const void *wxDataObject::GetSizeFromBuffer(const void *buffer,
+                                            size_t *size,
+                                            const wxDataFormat& format)
 {
     // hack: the third parameter is declared non-const in Wine's headers so
     // cast away the const
-    size_t realsz = ::HeapSize(::GetProcessHeap(), 0,
-                               wx_const_cast(void*, buffer));
+    const size_t realsz = ::HeapSize(::GetProcessHeap(), 0,
+                                     wx_const_cast(void*, buffer));
     if ( realsz == (size_t)-1 )
     {
         // note that HeapSize() does not set last error
@@ -702,9 +703,13 @@ const void* wxDataObject::GetSizeFromBuffer( const void* buffer, size_t* size,
     *size = realsz;
 
     // check if this data has its size prepended (as it was by default for wx
-    // programs prior 2.6.3):
-    size_t *p = (size_t *)buffer;
-    if ( *p == realsz )
+    // programs prior 2.6.3): notice that we may still mistakenly interpret the
+    // start of the real data as size (e.g. suppose the object contains 2 ints
+    // and the first of them is 8...) but there is no way around it as long as
+    // we want to keep this compatibility hack (it won't be there any more in
+    // the next major wx version)
+    DWORD *p = (DWORD *)buffer;
+    if ( *p == realsz && realsz > sizeof(DWORD) )
     {
         if ( NeedsVerbatimData(format) )
             wxLogDebug(wxT("Apparent data format mismatch: size not needed"));