[gtk/gtk-3-24: 3/8] gdk/win32: Consolidate CPU detection in one place

[Luca Bacci <lbacci src gnome org>]

commit 4a55c527d7a68a05d133d97eeec6bf3cfa3978bd
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Fri Oct 16 18:22:01 2020 +0800

    gdk/win32: Consolidate CPU detection in one place
    
    This consolidates the check for the running CPU in one single location,
    to make things a bit cleaner, as:
    
    * We can make use of IsWow64Process2(), if available, to check both
      whether we are running on an ARM64 CPU, and whether we are running as
      a WOW64 process.  This is also the function to use to properly check
      whether we are running as a WOW64 process on ARM64 systems, as
      IsWow64Process() does not work as we want on ARM64 systems.
    
    * If we don't have IsWow64Process2() (which is absent from Windows prior
      to Windows 10 1511, where ARM64 Windows is introduced), we can fall
      back to  IsWow64Process(), which will tell us whether we are running
      as an WOW64 process (but clearly not on an ARM64 system).
    
    Also clean up things a bit so that we can reduce reliance on global
    variables.

 gdk/win32/gdkdisplay-win32.c | 50 ++++++++++++++++++++++++++++++++++----------
 gdk/win32/gdkdisplay-win32.h |  1 -
 gdk/win32/gdkkeys-win32.c    | 22 +------------------
 gdk/win32/gdkprivate-win32.h |  8 +++++++
 4 files changed, 48 insertions(+), 33 deletions(-)
---
diff --git a/gdk/win32/gdkdisplay-win32.c b/gdk/win32/gdkdisplay-win32.c
index ff52b2bef9..246a6c9175 100644
--- a/gdk/win32/gdkdisplay-win32.c
+++ b/gdk/win32/gdkdisplay-win32.c
@@ -1034,42 +1034,70 @@ _gdk_win32_enable_hidpi (GdkWin32Display *display)
     }
 }
 
-#if 0
-/* Keep code around in case we need to check for running on ARM64 in the future */
-static void
-_gdk_win32_check_on_arm64 (GdkWin32Display *display)
+gboolean
+_gdk_win32_check_processor (GdkWin32ProcessorCheckType check_type)
 {
   static gsize checked = 0;
+  static gboolean is_arm64 = FALSE;
+  static gboolean is_wow64 = FALSE;
 
   if (g_once_init_enter (&checked))
     {
+      gboolean fallback_wow64_check = FALSE;
       HMODULE kernel32 = LoadLibraryW (L"kernel32.dll");
 
       if (kernel32 != NULL)
         {
-          display->cpu_funcs.isWow64Process2 =
+          GdkWin32KernelCPUFuncs cpu_funcs = {0};
+
+          cpu_funcs.isWow64Process2 =
             (funcIsWow64Process2) GetProcAddress (kernel32, "IsWow64Process2");
 
-          if (display->cpu_funcs.isWow64Process2 != NULL)
+          if (cpu_funcs.isWow64Process2 != NULL)
             {
               USHORT proc_cpu = 0;
               USHORT native_cpu = 0;
 
-              display->cpu_funcs.isWow64Process2 (GetCurrentProcess (),
-                                                  &proc_cpu,
-                                                  &native_cpu);
+              cpu_funcs.isWow64Process2 (GetCurrentProcess (),
+                                        &proc_cpu,
+                                        &native_cpu);
 
               if (native_cpu == IMAGE_FILE_MACHINE_ARM64)
-                display->running_on_arm64 = TRUE;
+                is_arm64 = TRUE;
+
+              if (native_cpu != IMAGE_FILE_MACHINE_UNKNOWN)
+                is_wow64 = TRUE;
             }
+          else
+            fallback_wow64_check = TRUE;
 
           FreeLibrary (kernel32);
         }
+      else
+        fallback_wow64_check = TRUE;
+
+      if (fallback_wow64_check)
+        IsWow64Process (GetCurrentProcess (), &is_wow64);
 
       g_once_init_leave (&checked, 1);
     }
+
+  switch (check_type)
+    {
+      case GDK_WIN32_ARM64:
+        return is_arm64;
+        break;
+
+      case GDK_WIN32_WOW64:
+        return is_wow64;
+        break;
+
+      default:
+        g_warning ("unknown CPU check type");
+        return FALSE;
+        break;
+    }
 }
-#endif
 
 static void
 gdk_win32_display_init (GdkWin32Display *display)
diff --git a/gdk/win32/gdkdisplay-win32.h b/gdk/win32/gdkdisplay-win32.h
index 4d6ac732a6..806e4430e2 100644
--- a/gdk/win32/gdkdisplay-win32.h
+++ b/gdk/win32/gdkdisplay-win32.h
@@ -124,7 +124,6 @@ struct _GdkWin32Display
   GdkWin32User32DPIFuncs user32_dpi_funcs;
 
   /* Running CPU items */
-  GdkWin32KernelCPUFuncs cpu_funcs;
 };
 
 struct _GdkWin32DisplayClass
diff --git a/gdk/win32/gdkkeys-win32.c b/gdk/win32/gdkkeys-win32.c
index f028e05460..a5b606ef74 100644
--- a/gdk/win32/gdkkeys-win32.c
+++ b/gdk/win32/gdkkeys-win32.c
@@ -80,26 +80,6 @@ static GdkKeymap *default_keymap = NULL;
 static void update_keymap              (GdkWin32Keymap *gdk_keymap);
 static void clear_keyboard_layout_info (gpointer        data);
 
-#ifndef _WIN64
-static BOOL
-is_wow64 (void)
-{
-  typedef BOOL (WINAPI *LPFN_ISWOW64PROCESS) (HANDLE, PBOOL);
-
-  BOOL bIsWow64 = FALSE;
-  LPFN_ISWOW64PROCESS fnIsWow64Process;
-
-  fnIsWow64Process = (LPFN_ISWOW64PROCESS)
-                     GetProcAddress (GetModuleHandle (TEXT("kernel32")),
-                                     "IsWow64Process");
-
-  if (fnIsWow64Process != NULL)
-    fnIsWow64Process (GetCurrentProcess (), &bIsWow64);
-
-  return bIsWow64;
-}
-#endif
-
 static void
 gdk_win32_keymap_init (GdkWin32Keymap *keymap)
 {
@@ -122,7 +102,7 @@ gdk_win32_keymap_init (GdkWin32Keymap *keymap)
 
   keymap->gdkwin32_keymap_impl = &gdkwin32_keymap_impl;
 #ifndef _WIN64
-  if (is_wow64())
+  if (_gdk_win32_check_processor (GDK_WIN32_WOW64))
     keymap->gdkwin32_keymap_impl = &gdkwin32_keymap_impl_wow64;
 #endif
 
diff --git a/gdk/win32/gdkprivate-win32.h b/gdk/win32/gdkprivate-win32.h
index 6667df5f1e..e06aafc820 100644
--- a/gdk/win32/gdkprivate-win32.h
+++ b/gdk/win32/gdkprivate-win32.h
@@ -542,4 +542,12 @@ void _gdk_win32_windowing_init (void);
 void _gdk_dnd_init    (void);
 void _gdk_events_init (GdkDisplay *display);
 
+typedef enum _GdkWin32ProcessorCheckType
+{
+  GDK_WIN32_ARM64,
+  GDK_WIN32_WOW64,
+} GdkWin32ProcessorCheckType;
+
+gboolean _gdk_win32_check_processor (GdkWin32ProcessorCheckType check_type);
+
 #endif /* __GDK_PRIVATE_WIN32_H__ */