[PATCH 1/1] dwmapi: Fallback to 60Hz if the display frequency is invalid in get_display_frequency().

[Zhiyi Zhang]

From: Zhiyi Zhang

DwmGetCompositionTimingInfo() may throw a zero division exception if the display reports a 0Hz
frequency, which can happen when testing under Xephyr without -fakescreenfps option.
---
 dlls/dwmapi/dwmapi_main.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/dlls/dwmapi/dwmapi_main.c b/dlls/dwmapi/dwmapi_main.c
index 1a65410c7eb..56730f79cac 100644
--- a/dlls/dwmapi/dwmapi_main.c
+++ b/dlls/dwmapi/dwmapi_main.c
@@ -213,12 +213,16 @@ HRESULT WINAPI DwmRegisterThumbnail(HWND dest, HWND src, PHTHUMBNAIL thumbnail_i

static int get_display_frequency(void)
 {
-    DEVMODEA mode;
+    DEVMODEW mode;
+    BOOL ret;

memset(&mode, 0, sizeof(mode));
     mode.dmSize = sizeof(mode);
-    if (EnumDisplaySettingsA(NULL, ENUM_CURRENT_SETTINGS, &mode))
+    ret = EnumDisplaySettingsExW(NULL, ENUM_CURRENT_SETTINGS, &mode, 0);
+    if (ret && mode.dmFields & DM_DISPLAYFREQUENCY && mode.dmDisplayFrequency)
+    {
         return mode.dmDisplayFrequency;
+    }
     else
     {
         WARN("Failed to query display frequency, returning a fallback value.\n");