[PATCH v3] mingw: replace deprecated GetVersion with RtlGetVersion

From: Seija Kijin <doremylover123@gmail.com>

The previous way is deprecated and returns the wrong value in Windows 8 and up, returning the manifest Windows data as opposed to the actual Windows data.

RtlGetVersion is the correct way to get the Windows version now.

Note: ntdll does not need to be
manually loaded into the runtime,
as this is the one special library
that is automatically loaded upon launch.

Signed-off-by: Seija Kijin <doremylover123@gmail.com>
---
    mingw: replace deprecated GetVersion with RtlGetVersion
    
    GetVersion has its behavior changed in Windows 8 and above anyway, so
    this is the right way to do it now.
    
    The previous way returns the wrong value in Windows 8 and up, returning
    the manifest Windows data as opposed to the actual Windows data.
    
    Signed-off-by: Seija Kijin doremylover123@gmail.com

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1438%2FAtariDreams%2Fmingw-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1438/AtariDreams/mingw-v3
Pull-Request: https://github.com/git/git/pull/1438

Range-diff vs v2:

 1:  e5457905028 ! 1:  31f778a6b34 mingw: replace deprecated GetVersion with RtlGetVersion
     @@ Commit message
          returning the manifest Windows data
          as opposed to the actual Windows data.
      
     -    RtlGetVersion is the correct way to get the Windows version now.
     +    RtlGetVersion is the correct way
     +    to get the Windows version now.
     +
     +    Note: ntdll does not need to be
     +    manually loaded into the runtime,
     +    as this is the one special library
     +    that is automatically loaded upon launch.
      
          Signed-off-by: Seija Kijin <doremylover123@gmail.com>
      
     @@ compat/mingw.c: int wmain(int argc, const wchar_t **wargv)
       {
      -	unsigned v = (unsigned)GetVersion();
      +	union winprocaddr RtlGetVersionInternal;
     -+	OSVERSIONINFOA version;
     ++	OSVERSIONINFOW version;
     ++
     ++	memset(&version, 0, sizeof(version));
     ++	version.dwOSVersionInfoSize = sizeof(version);
      +
     ++	/* RtlGetVersion always gets the true Windows version, even when running
     ++	 * under Windows's compatibility mode*/
      +	RtlGetVersionInternal.procaddr =
      +		GetProcAddress(GetModuleHandleW(L"ntdll.dll"), "RtlGetVersion");
     -+	if (!RtlGetVersionInternal.procaddr) {
     -+		/* if this is reached, something is seriously, seriously wrong
     -+		 */
     -+		perror("Could not call RtlGetVersion in ntdll.dll");
     -+		abort();
     -+	}
      +
     -+	version.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
     -+	RtlGetVersionInternal.procGetVersion((PRTL_OSVERSIONINFOW)&version);
     ++	if (RtlGetVersionInternal.procaddr) {
     ++		RtlGetVersionInternal.procGetVersion((PRTL_OSVERSIONINFOW)&version);
     ++	} else {
     ++		/* Should not happen, but just in case, fallback to deprecated
     ++		 * GetVersionExW */
     ++		GetVersionExW(&version);
     ++	}
      +
       	memset(buf, 0, sizeof(*buf));
       	xsnprintf(buf->sysname, sizeof(buf->sysname), "Windows");

 compat/mingw.c | 39 +++++++++++++++++++++++++++++++++------
 1 file changed, 33 insertions(+), 6 deletions(-)