Etc.uname: Report the actual Windows version

GetVersionEx reports 6.2.9200 on Windows 8.1 and later unless the manifest of the executable declares them as supported, and ruby.manifest does not. RtlGetVersion is not affected by the manifest.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ext/etc/etc.c

@@ -800,6 +800,8 @@ static VALUE
 etc_uname(VALUE obj)
 {
 #ifdef _WIN32
+    typedef long (WINAPI version_func)(OSVERSIONINFOW *);
+    version_func *pRtlGetVersion;
     OSVERSIONINFOW v;
     SYSTEM_INFO s;
     const char *sysname, *mach;
@@ -808,9 +810,11 @@ etc_uname(VALUE obj)
     DWORD len = 0;
     WCHAR *buf;
 
+    /* GetVersionEx reports 6.2 unless the manifest declares Windows 8.1 or later */
+    pRtlGetVersion = (version_func *)GetProcAddress(GetModuleHandleW(L"ntdll.dll"), "RtlGetVersion");
     v.dwOSVersionInfoSize = sizeof(v);
-    if (!GetVersionExW(&v))
-        rb_sys_fail("GetVersionEx");
+    if (!pRtlGetVersion || pRtlGetVersion(&v))
+        rb_notimplement();
 
     result = rb_hash_new();
     sysname = "Windows_NT";

test/etc/test_etc.rb

@@ -131,6 +131,11 @@ class TestEtc < Test::Unit::TestCase
     }
   end
 
+  def test_uname_release_on_windows
+    release = IO.popen(%w[cmd.exe /c ver], "rb", &:read)[/\d+\.\d+\.\d+/]
+    assert_equal(release, Etc.uname[:release])
+  end if /mswin|mingw/ =~ RUBY_PLATFORM
+
   def test_sysconf
     begin
       Etc.sysconf