Consolidate winerror message handling in modules _ctpyes and nt (#1470)

Author: BCSharp

Src/IronPython.Modules/_ctypes/_ctypes.cs

@@ -166,23 +166,16 @@ public static int CopyComPointer(object src, object dest) {
 
 #nullable enable
 
+        [SupportedOSPlatform("windows"), PythonHidden(PlatformsAttribute.PlatformFamily.Unix)]
         public static string FormatError() {
             return FormatError(get_last_error());
         }
 
+        [SupportedOSPlatform("windows"), PythonHidden(PlatformsAttribute.PlatformFamily.Unix)]
         public static string FormatError(int errorCode) {
             return new Win32Exception(errorCode).Message;
         }
 
-        private static string FormatError(int errorCode, string? fileName) {
-            string msg = FormatError(errorCode);
-            // error codes: https://docs.microsoft.com/en-us/windows/win32/debug/system-error-codes
-            if (errorCode is not (< 0 or >= 8200 or 34 or 106 or 317 or 718)) {
-                msg = msg.Replace("%1", $"'{fileName}'");
-            }
-            return msg;
-        }
-
         [SupportedOSPlatform("windows"), PythonHidden(PlatformsAttribute.PlatformFamily.Unix)]
         public static void FreeLibrary(int handle) {
             FreeLibrary(new IntPtr(handle));
@@ -203,9 +196,7 @@ private static object LoadDLL(string? library, int mode) {
             IntPtr res = NativeFunctions.LoadDLL(library, mode);
             if (res == IntPtr.Zero) {
                 if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows)) {
-                    int code = NativeFunctions.GetLastError();
-                    string msg = FormatError(code, library);
-                    throw PythonExceptions.CreateThrowable(PythonExceptions.OSError, 0, msg, null, code);
+                    throw PythonNT.GetLastWin32Error(library);
                 }
 
                 throw PythonOps.OSError("cannot load library '{0}'", library);
@@ -430,6 +421,7 @@ public static int get_errno() {
             return 0;
         }
 
+        [SupportedOSPlatform("windows"), PythonHidden(PlatformsAttribute.PlatformFamily.Unix)]
         public static int get_last_error() {
             if (Environment.OSVersion.Platform == PlatformID.Win32NT) {
                 return NativeFunctions.GetLastError();

Src/IronPython.Modules/nt.cs

@@ -2055,7 +2055,7 @@ private static Exception ToPythonException(Exception e, string? filename = null)
                 return PythonOps.OSError(errorCode, message, filename, errorCode);
             }
 
-            return PythonExceptions.CreateThrowable(PythonExceptions.OSError, errorCode, message);
+            return PythonOps.OSError(errorCode, message, filename);
         }
 
         private static Exception? IOExceptionToPythonException(IOException? ioe, int error, string? filename) {
@@ -2214,29 +2214,22 @@ private static Exception GetUnixError(int error, string? filename = null, string
             return PythonOps.OSError(error, msg, filename, null, filename2);
         }
 
-        [DllImport("kernel32.dll", EntryPoint = "FormatMessageW", SetLastError = true, CharSet = CharSet.Unicode, BestFitMapping = true)]
-        private static extern int FormatMessage(int dwFlags, IntPtr lpSource,
-                    int dwMessageId, int dwLanguageId, [Out] StringBuilder lpBuffer,
-                    int nSize, IntPtr arguments);
+#endif
 
-        private const int FORMAT_MESSAGE_IGNORE_INSERTS = 0x00000200;
-        private const int FORMAT_MESSAGE_FROM_SYSTEM = 0x00001000;
-        private const int ERROR_INSUFFICIENT_BUFFER = 0x7A;
+#if FEATURE_NATIVE || FEATURE_CTYPES
 
         // Gets an error message for a Win32 error code.
         internal static string GetMessage(int errorCode) {
-            var buf = new StringBuilder(256);
-            int msgLen = 0;
-            int lastError = ERROR_INSUFFICIENT_BUFFER;
-            while (msgLen == 0 && lastError == ERROR_INSUFFICIENT_BUFFER) {
-                msgLen = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, IntPtr.Zero, errorCode, 0, buf, buf.Capacity, IntPtr.Zero);
-                if (msgLen == 0) {
-                    lastError = Marshal.GetLastWin32Error();
-                    if (lastError == ERROR_INSUFFICIENT_BUFFER)
-                        buf.Capacity *= 2;
-                }
-            }
-            return buf.ToString().TrimEnd('\r', '\n', '.');
+            string msg = new Win32Exception(errorCode).Message;
+            // error codes: https://docs.microsoft.com/en-us/windows/win32/debug/system-error-codes
+            if (errorCode is not (< 0 or >= 8200 or 34 or 106 or 317 or 718)) {
+                msg = msg.IndexOf('%') switch {
+                    0 => "The file specified" + msg.Substring(2),
+                    > 0 => msg.Replace("%1", "the file specified"),
+                    _ => msg
+                };
+            }
+            return msg.TrimEnd('\r', '\n', '.');
         }
 
         internal static Exception GetLastWin32Error(string? filename = null, string? filename2 = null)

Tests/modules/type_related/test_ctypes.py

@@ -228,7 +228,10 @@ def test_loadlibrary_error(self):
         self.assertEqual(cm.exception.errno, 8)
         self.assertEqual(cm.exception.winerror, 193)
         self.assertIn(" is not a valid Win32 application", cm.exception.strerror)
-        self.assertIsNone(cm.exception.filename)
+        if is_cli:
+            self.assertEqual(cm.exception.filename, __file__)
+        else:
+            self.assertIsNone(cm.exception.filename)
         self.assertIsNone(cm.exception.filename2)
 
 run_test(__name__)