Fix _add_dll_directory

Fixes #533

Author: msimacek

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/cext/capi/CApiContext.java

@@ -73,6 +73,7 @@
 import org.graalvm.shadowed.com.ibm.icu.text.StringPrepParseException;
 
 import com.oracle.graal.python.PythonLanguage;
+import com.oracle.graal.python.annotations.PythonOS;
 import com.oracle.graal.python.builtins.PythonBuiltinClassType;
 import com.oracle.graal.python.builtins.modules.cext.PythonCApiAssertions;
 import com.oracle.graal.python.builtins.modules.cext.PythonCextBuiltinRegistry;
@@ -1078,7 +1079,11 @@ public static Object loadCExtModule(Node location, PythonContext context, Module
             }
             dlopenFlags |= PosixConstants.RTLD_LOCAL.value;
         }
-        String loadExpr = String.format("load(%s) \"%s\"", dlopenFlagsToString(dlopenFlags), loadPath);
+        String dlopenFlagsString = dlopenFlagsToString(dlopenFlags);
+        if (PythonLanguage.getPythonOS() == PythonOS.PLATFORM_WIN32) {
+            dlopenFlagsString += "| LOAD_LIBRARY_SEARCH_DEFAULT_DIRS | LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR";
+        }
+        String loadExpr = String.format("load(%s) \"%s\"", dlopenFlagsString, loadPath);
         if (PythonOptions.UsePanama.getValue(context.getEnv().getOptions())) {
             loadExpr = "with panama " + loadExpr;
         }

graalpython/lib-graalpython/_nt.py

@@ -41,13 +41,21 @@
 
 
 def _add_dll_directory(path):
+    # TODO error handling
     import ctypes
-    return ctypes.windll.kernel32.AddDllDirectory(path)
+    AddDllDirectory = ctypes.windll.kernel32['AddDllDirectory']
+    AddDllDirectory.argtypes = [ctypes.c_wchar_p]
+    AddDllDirectory.restype = ctypes.c_void_p
+    return AddDllDirectory(path)
 
 
 def _remove_dll_directory(cookie):
+    # TODO error handling
     import ctypes
-    return ctypes.windll.kernel32.RemoveDllDirectory(cookie)
+    RemoveDllDirectory = ctypes.windll.kernel32['RemoveDllDirectory']
+    RemoveDllDirectory.argtypes = [ctypes.c_void_p]
+    RemoveDllDirectory.restype = ctypes.c_int
+    RemoveDllDirectory(cookie)
 
 
 nt._add_dll_directory = _add_dll_directory