ntdll: Fix RtlCheckRegistryKey when called with empty path.

dlls/ntdll/reg.c

@@ -1401,10 +1401,12 @@ NTSTATUS WINAPI RtlCheckRegistryKey(IN ULONG RelativeTo, IN PWSTR Path)
 
     TRACE("(%d, %s)\n", RelativeTo, debugstr_w(Path));
 
-    if((!RelativeTo) && Path == NULL)
+    if(!RelativeTo && (Path == NULL || Path[0] == 0))
         return STATUS_OBJECT_PATH_SYNTAX_BAD;
     if(RelativeTo & RTL_REGISTRY_HANDLE)
         return STATUS_SUCCESS;
+    if((RelativeTo <= RTL_REGISTRY_USER) && (Path == NULL || Path[0] == 0))
+        return STATUS_SUCCESS;
 
     status = RTL_GetKeyHandle(RelativeTo, Path, &handle);
     if (handle) NtClose(handle);

dlls/ntdll/tests/reg.c

@@ -671,6 +671,7 @@ static void test_RtlOpenCurrentUser(void)
 
 static void test_RtlCheckRegistryKey(void)
 {
+    static WCHAR empty[] = {0};
     NTSTATUS status;
 
     status = pRtlCheckRegistryKey(RTL_REGISTRY_ABSOLUTE, winetestpath.Buffer);
@@ -678,6 +679,18 @@ static void test_RtlCheckRegistryKey(void)
 
     status = pRtlCheckRegistryKey((RTL_REGISTRY_ABSOLUTE | RTL_REGISTRY_OPTIONAL), winetestpath.Buffer);
     ok(status == STATUS_SUCCESS, "RtlCheckRegistryKey with RTL_REGISTRY_ABSOLUTE and RTL_REGISTRY_OPTIONAL: 0x%08x\n", status);
+
+    status = pRtlCheckRegistryKey(RTL_REGISTRY_ABSOLUTE, NULL);
+    ok(status == STATUS_OBJECT_PATH_SYNTAX_BAD, "RtlCheckRegistryKey with RTL_REGISTRY_ABSOLUTE and Path being NULL: 0x%08x\n", status);
+
+    status = pRtlCheckRegistryKey(RTL_REGISTRY_ABSOLUTE, empty);
+    ok(status == STATUS_OBJECT_PATH_SYNTAX_BAD, "RtlCheckRegistryKey with RTL_REGISTRY_ABSOLUTE and Path being empty: 0x%08x\n", status);
+
+    status = pRtlCheckRegistryKey(RTL_REGISTRY_USER, NULL);
+    ok(status == STATUS_SUCCESS, "RtlCheckRegistryKey with RTL_REGISTRY_USER and Path being NULL: 0x%08x\n", status);
+
+    status = pRtlCheckRegistryKey(RTL_REGISTRY_USER, empty);
+    ok(status == STATUS_SUCCESS, "RtlCheckRegistryKey with RTL_REGISTRY_USER and Path being empty: 0x%08x\n", status);
 }
 
 static void test_NtFlushKey(void)