oledb32: Support VT_NULL when converting to DBTYPE_BSTR

[Alistair Leslie-Hughes]

Hi,


Changelog:
     oledb32:  Support VT_NULL when converting to DBTYPE_BSTR


Best Regards
  Alistair Leslie-Hughes
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>From 73d76d75d89d9ed9630bd983b5f175180bf6405a Mon Sep 17 00:00:00 2001
From: Alistair Leslie-Hughes <leslie_alistair at hotmail.com>
Date: Fri, 17 May 2013 12:21:12 +1000
Subject: [PATCH] Support VT_NULL when converting to DBTYPE_BSTR
To: wine-patches <wine-patches at winehq.org>

---
 dlls/oledb32/convert.c       | 19 +++++++++++++++----
 dlls/oledb32/tests/convert.c |  8 ++++++++
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/dlls/oledb32/convert.c b/dlls/oledb32/convert.c
index 19f46f6..0cd9e53 100644
--- a/dlls/oledb32/convert.c
+++ b/dlls/oledb32/convert.c
@@ -534,10 +534,21 @@ static HRESULT WINAPI convert_DataConvert(IDataConvert* iface,
         }
         break;
         case DBTYPE_VARIANT:
-            VariantInit(&tmp);
-            if ((hr = VariantChangeType(&tmp, (VARIANT*)src, 0, VT_BSTR)) == S_OK)
-                *d = V_BSTR(&tmp);
-            break;
+        {
+            if(V_VT((VARIANT*)src) == VT_NULL)
+            {
+                *dst_status = DBSTATUS_S_ISNULL;
+                *dst_len = get_length(DBTYPE_BSTR);
+                return S_OK;
+            }
+            else
+            {
+                VariantInit(&tmp);
+                if ((hr = VariantChangeType(&tmp, (VARIANT*)src, 0, VT_BSTR)) == S_OK)
+                    *d = V_BSTR(&tmp);
+            }
+        }
+        break;
         default: FIXME("Unimplemented conversion %04x -> BSTR\n", src_type); return E_NOTIMPL;
         }
         break;
diff --git a/dlls/oledb32/tests/convert.c b/dlls/oledb32/tests/convert.c
index 90e1658..6f02899 100644
--- a/dlls/oledb32/tests/convert.c
+++ b/dlls/oledb32/tests/convert.c
@@ -977,6 +977,14 @@ static void test_converttobstr(void)
     ok(!lstrcmpW(b, dst), "got %s\n", wine_dbgstr_w(dst));
     SysFreeString(dst);
     SysFreeString(b);
+
+    V_VT(&v) = VT_NULL;
+    dst = (void*)0x1234;
+    hr = IDataConvert_DataConvert(convert, DBTYPE_VARIANT, DBTYPE_BSTR, 0, &dst_len, &v, &dst, sizeof(dst), 0, &dst_status, 0, 0, 0);
+    ok(hr == S_OK, "got %08x\n", hr);
+    ok(dst_status == DBSTATUS_S_ISNULL, "got %08x\n", dst_status);
+    ok(dst_len == sizeof(BSTR), "got %ld\n", dst_len);
+    ok(dst == (void*)0x1234, "got %p\n", dst);
 }
 
 static void test_converttowstr(void)
-- 
1.8.1.2