From 8d5d413697e92042c64a6a77894b88eed063a8b7 Mon Sep 17 00:00:00 2001
From: Zhiyi Zhang <zzhang@codeweavers.com>
Date: Wed, 27 Sep 2023 15:57:53 +0800
Subject: [PATCH] user32: Enable IsDialogMessageA() ASCII to Unicode mapping
 only when the user default lang ID is CJK.

Using GetSystemMetrics(SM_DBCSENABLED) may incorrectly enable ASCII to Unicode mapping in mixed
locale environments. For example, when UserDefaultLCID is French(040c) but SystemDefaultLCID is
Japanese(0411).

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=55655
---
 dlls/user32/message.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/dlls/user32/message.c b/dlls/user32/message.c
index 4016c95539a..86c6593e192 100644
--- a/dlls/user32/message.c
+++ b/dlls/user32/message.c
@@ -807,6 +807,14 @@ BOOL WINAPI DECLSPEC_HOTPATCH GetMessageA( MSG *msg, HWND hwnd, UINT first, UINT
     return (msg->message != WM_QUIT);
 }
 
+static BOOL is_cjk(void)
+{
+    int lang_id = PRIMARYLANGID(GetUserDefaultLangID());
+
+    if (lang_id == LANG_CHINESE || lang_id == LANG_JAPANESE || lang_id == LANG_KOREAN)
+        return TRUE;
+    return FALSE;
+}
 
 /***********************************************************************
  *		IsDialogMessageA (USER32.@)
@@ -817,7 +825,7 @@ BOOL WINAPI IsDialogMessageA( HWND hwndDlg, LPMSG pmsg )
     enum wm_char_mapping mapping;
     MSG msg = *pmsg;
 
-    mapping = GetSystemMetrics( SM_DBCSENABLED ) ? WMCHAR_MAP_ISDIALOGMESSAGE : WMCHAR_MAP_NOMAPPING;
+    mapping = is_cjk() ? WMCHAR_MAP_ISDIALOGMESSAGE : WMCHAR_MAP_NOMAPPING;
     if (!map_wparam_AtoW( msg.message, &msg.wParam, mapping ))
         return TRUE;
     return IsDialogMessageW( hwndDlg, &msg );