Fix platform version for Windows 10/11 using RtlGetVersion()

We've added a new show_platform example to check the reported
platform by the base::get_platform() function.

base/platform.cpp

@@ -1,5 +1,5 @@
 // LAF Base Library
-// Copyright (c) 2021  Igara Studio S.A.
+// Copyright (c) 2021-2024  Igara Studio S.A.
 //
 // This file is released under the terms of the MIT license.
 // Read LICENSE.txt for more information.
@@ -12,6 +12,8 @@
 
 #if LAF_WINDOWS
   #include <windows.h>
+
+  typedef LONG (WINAPI* RtlGetVersion_Func)(OSVERSIONINFOEX*);
 #elif LAF_LINUX  // Unix-like system
   #include <sys/utsname.h>
 #endif
@@ -29,9 +31,28 @@ Platform get_platform()
 
   OSVERSIONINFOEX osv;
   osv.dwOSVersionInfoSize = sizeof(OSVERSIONINFOEX);
-  ::GetVersionEx((OSVERSIONINFO*)&osv);
 
-  p.osVer = Version(osv.dwMajorVersion, osv.dwMinorVersion, 0, 0);
+  // It looks like GetVersionEx() returns 6.2 for all Windows versions
+  // after Windows 8 and RtlGetVersion() returns the correct version
+  // and build number for Windows 10 and 11.
+  static const auto fnRtlGetVersion = reinterpret_cast<RtlGetVersion_Func>(
+    GetProcAddress(GetModuleHandle(L"ntdll.dll"),
+                   "RtlGetVersion"));
+  if (!fnRtlGetVersion ||
+      !fnRtlGetVersion(&osv) ||
+      !osv.dwMajorVersion) {
+    OSVERSIONINFOEX osv;
+    osv.dwOSVersionInfoSize = sizeof(OSVERSIONINFOEX);
+    // Ignore deprecated function warning
+#pragma warning(push)
+#pragma warning(disable : 4996)
+    GetVersionEx((OSVERSIONINFO*)&osv);
+#pragma warning(pop)
+  }
+
+  p.osVer = Version(osv.dwMajorVersion,
+                    osv.dwMinorVersion,
+                    osv.dwBuildNumber, 0);
   switch (osv.wProductType) {
     case VER_NT_DOMAIN_CONTROLLER:
     case VER_NT_SERVER:

examples/CMakeLists.txt

@@ -23,4 +23,5 @@ if(LAF_BACKEND STREQUAL "skia")
   laf_add_example(multiple_windows GUI)
   laf_add_example(panviewport GUI)
   laf_add_example(shader GUI)
+  laf_add_example(show_platform CONSOLE)
 endif()

examples/show_platform.cpp

@@ -0,0 +1,50 @@
+// LAF Library
+// Copyright (c) 2024  Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#include "base/platform.h"
+
+#include <cstdio>
+
+int app_main(int argc, char* argv[])
+{
+  base::Platform p =  base::get_platform();
+  switch (p.os) {
+#if LAF_WINDOWS
+    case base::Platform::OS::Windows:
+      std::printf(
+        "Windows v%s%s%s",
+        p.osVer.str().c_str(),
+        p.isWow64 ? " WoW64": "",
+        (p.wineVer ? (std::string(" WINE v") + p.wineVer).c_str(): ""));
+      break;
+#endif
+    case base::Platform::OS::macOS:
+      std::printf(
+        "macOS v%s",
+        p.osVer.str().c_str());
+      break;
+#if LAF_LINUX
+    case base::Platform::OS::Linux:
+      std::printf("Linux %s", p.distroName.c_str());
+      if (!p.distroVer.empty())
+        std::printf(" %s", p.distroVer.c_str());
+      break;
+#endif
+  }
+  switch (p.arch) {
+    case base::Platform::Arch::x86:
+      std::printf(" (x86)");
+      break;
+    case base::Platform::Arch::x64:
+      std::printf(" (x64)");
+      break;
+    case base::Platform::Arch::arm64:
+      std::printf(" (arm64)");
+      break;
+  }
+  std::printf("\n");
+  return 0;
+}