dxdiagn: Initialize output pointer to NULL in IDxDiagContainer::GetChildContainer.

dlls/dxdiagn/container.c

@@ -129,7 +129,7 @@ static HRESULT IDxDiagContainerImpl_GetChildContainerInternal(PDXDIAGCONTAINER i
 
 static HRESULT WINAPI IDxDiagContainerImpl_GetChildContainer(PDXDIAGCONTAINER iface, LPCWSTR pwszContainer, IDxDiagContainer** ppInstance) {
   IDxDiagContainerImpl *This = (IDxDiagContainerImpl *)iface;
-  IDxDiagContainer* pContainer = NULL;
+  IDxDiagContainer* pContainer = (PDXDIAGCONTAINER)This;
   LPWSTR tmp, orig_tmp;
   INT tmp_len;
   WCHAR* cur;
@@ -141,7 +141,7 @@ static HRESULT WINAPI IDxDiagContainerImpl_GetChildContainer(PDXDIAGCONTAINER if
     return E_INVALIDARG;
   }
 
-  pContainer = (PDXDIAGCONTAINER) This;
+  *ppInstance = NULL;
 
   tmp_len = strlenW(pwszContainer) + 1;
   orig_tmp = tmp = HeapAlloc(GetProcessHeap(), 0, tmp_len * sizeof(WCHAR));

dlls/dxdiagn/tests/container.c

@@ -219,11 +219,82 @@ cleanup:
     IDxDiagProvider_Release(pddp);
 }
 
+static void test_GetChildContainer(void)
+{
+    HRESULT hr;
+    WCHAR container[256] = {0};
+    IDxDiagContainer *child;
+
+    if (!create_root_IDxDiagContainer())
+    {
+        skip("Unable to create the root IDxDiagContainer\n");
+        return;
+    }
+
+    /* Test various combinations of invalid parameters. */
+    hr = IDxDiagContainer_GetChildContainer(pddc, NULL, NULL);
+    ok(hr == E_INVALIDARG,
+       "Expected IDxDiagContainer::GetChildContainer to return E_INVALIDARG, got 0x%08x\n", hr);
+
+    child = (void*)0xdeadbeef;
+    hr = IDxDiagContainer_GetChildContainer(pddc, NULL, &child);
+    ok(hr == E_INVALIDARG,
+       "Expected IDxDiagContainer::GetChildContainer to return E_INVALIDARG, got 0x%08x\n", hr);
+    ok(child == (void*)0xdeadbeef, "Expected output pointer to be unchanged, got %p\n", child);
+
+    hr = IDxDiagContainer_GetChildContainer(pddc, container, NULL);
+    ok(hr == E_INVALIDARG,
+       "Expected IDxDiagContainer::GetChildContainer to return E_INVALIDARG, got 0x%08x\n", hr);
+
+    child = (void*)0xdeadbeef;
+    hr = IDxDiagContainer_GetChildContainer(pddc, container, &child);
+    ok(hr == E_INVALIDARG,
+       "Expected IDxDiagContainer::GetChildContainer to return E_INVALIDARG, got 0x%08x\n", hr);
+    ok(child == NULL, "Expected output pointer to be NULL, got %p\n", child);
+
+    /* Get the name of a suitable child container. */
+    hr = IDxDiagContainer_EnumChildContainerNames(pddc, 0, container, sizeof(container)/sizeof(WCHAR));
+    ok(hr == S_OK,
+       "Expected IDxDiagContainer::EnumChildContainerNames to return S_OK, got 0x%08x\n", hr);
+    if (FAILED(hr))
+    {
+        skip("IDxDiagContainer::EnumChildContainerNames failed\n");
+        goto cleanup;
+    }
+
+    child = (void*)0xdeadbeef;
+    hr = IDxDiagContainer_GetChildContainer(pddc, container, &child);
+    ok(hr == S_OK,
+       "Expected IDxDiagContainer::GetChildContainer to return S_OK, got 0x%08x\n", hr);
+    ok(child != NULL && child != (void*)0xdeadbeef, "Expected a valid output pointer, got %p\n", child);
+
+    if (SUCCEEDED(hr))
+    {
+        IDxDiagContainer *ptr;
+
+        /* Show that IDxDiagContainer::GetChildContainer returns a different pointer
+         * for multiple calls for the same container name. */
+        hr = IDxDiagContainer_GetChildContainer(pddc, container, &ptr);
+        ok(hr == S_OK,
+           "Expected IDxDiagContainer::GetChildContainer to return S_OK, got 0x%08x\n", hr);
+        if (SUCCEEDED(hr))
+            todo_wine ok(ptr != child, "Expected the two pointers (%p vs. %p) to be unequal", child, ptr);
+
+        IDxDiagContainer_Release(ptr);
+        IDxDiagContainer_Release(child);
+    }
+
+cleanup:
+    IDxDiagContainer_Release(pddc);
+    IDxDiagProvider_Release(pddp);
+}
+
 START_TEST(container)
 {
     CoInitialize(NULL);
     test_GetNumberOfChildContainers();
     test_GetNumberOfProps();
     test_EnumChildContainerNames();
+    test_GetChildContainer();
     CoUninitialize();
 }