Re: [PATCH 2/5] util/oslib-win32: Add a helper to get the Windows version

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Jul 27, 2022 at 07:55:40PM +0800, Bin Meng wrote:
> On Wed, Jul 27, 2022 at 6:00 PM Daniel P. Berrangé <berrange@redhat.com> wrote:
> >
> > On Wed, Jul 27, 2022 at 05:38:27PM +0800, Bin Meng wrote:
> > > On Wed, Jul 27, 2022 at 4:50 PM Yan Vugenfirer <yvugenfi@redhat.com> wrote:
> > > >
> > > > On Wed, Jul 27, 2022 at 10:43 AM Bin Meng <bmeng.cn@gmail.com> wrote:
> > > > >
> > > > > From: Bin Meng <bin.meng@windriver.com>
> > > > >
> > > > > This adds a helper to get the Windows version via the RtlGetVersion
> > > > > call, for QEMU codes to determine the Windows version at run-time.
> > > > >
> > > > > Signed-off-by: Xuzhou Cheng <xuzhou.cheng@windriver.com>
> > > > > Signed-off-by: Bin Meng <bin.meng@windriver.com>
> > > > > ---
> > > > >
> > > > >  include/sysemu/os-win32.h |  2 ++
> > > > >  util/oslib-win32.c        | 15 +++++++++++++++
> > > > >  2 files changed, 17 insertions(+)
> > > > >
> > > > > diff --git a/include/sysemu/os-win32.h b/include/sysemu/os-win32.h
> > > > > index edc3b38a57..1e324026a4 100644
> > > > > --- a/include/sysemu/os-win32.h
> > > > > +++ b/include/sysemu/os-win32.h
> > > > > @@ -204,6 +204,8 @@ ssize_t qemu_recv_wrap(int sockfd, void *buf, size_t len, int flags);
> > > > >  ssize_t qemu_recvfrom_wrap(int sockfd, void *buf, size_t len, int flags,
> > > > >                             struct sockaddr *addr, socklen_t *addrlen);
> > > > >
> > > > > +void os_get_win_version(RTL_OSVERSIONINFOEXW *info);
> > > > > +
> > > > >  #ifdef __cplusplus
> > > > >  }
> > > > >  #endif
> > > > > diff --git a/util/oslib-win32.c b/util/oslib-win32.c
> > > > > index 5723d3eb4c..6d2387b9ff 100644
> > > > > --- a/util/oslib-win32.c
> > > > > +++ b/util/oslib-win32.c
> > > > > @@ -547,3 +547,18 @@ int qemu_msync(void *addr, size_t length, int fd)
> > > > >       */
> > > > >      return qemu_fdatasync(fd);
> > > > >  }
> > > > > +
> > > > > +void os_get_win_version(RTL_OSVERSIONINFOEXW *info)
> > > > > +{
> > > > > +    typedef LONG (WINAPI *rtl_get_version_t)(PRTL_OSVERSIONINFOEXW);
> > > > > +
> > > > > +    /* RtlGetVersion is available starting with Windows 2000 */
> > > > > +    HMODULE module = GetModuleHandle("ntdll");
> > > > > +    PVOID fun = GetProcAddress(module, "RtlGetVersion");
> > > > > +    rtl_get_version_t rtl_get_version = (rtl_get_version_t)fun;
> > > > > +
> > > > > +    info->dwOSVersionInfoSize = sizeof(RTL_OSVERSIONINFOEXW);
> > > > > +    rtl_get_version(info);
> > > > The original function, when it was present in qemu-ga, tested that
> > > > getting the function address succeeded.
> > > > I think this test should be kept.
> > > > See below:
> > > > -    PVOID fun = GetProcAddress(module, "RtlGetVersion");
> > > > -    if (fun == NULL) {
> > > > -        error_setg(errp, QERR_QGA_COMMAND_FAILED,
> > > > -            "Failed to get address of RtlGetVersion");
> > > > -        return;
> > > > -    }
> > > >
> > >
> > > Please see the comment:
> > >
> > > /* RtlGetVersion is available starting with Windows 2000 */
> > >
> > > I don't think we need that check.
> >
> > In include/qemu/osdep.h we have
> >
> > /* as defined in sdkddkver.h */
> > #ifndef _WIN32_WINNT
> > #define _WIN32_WINNT 0x0601 /* Windows 7 API (should be in sync with glib) */
> > #endif
> >
> > so do we even need to have the GetProcAddress calls at all ?
> >
> > Surely we can just  '#include <ddk/ntddk.h>' and call
> > RtlGetVersion directly at compile time ?
> >
> 
> I believe #include <ddk/ntddk.h> is used in the kernel mode driver
> programming environment.
> In the user space we will have to use the ntdll exported symbol.
> 
> I cannot locate a Microsoft doc that tells us to call RtlGetVersion
> directly in the user space.

I wonder if we actually need to add this helper API to QEMU at all.

Would it be possible to use GLib 's  g_win32_check_windows_version API
instead ?

https://developer-old.gnome.org/glib/unstable/glib-Windows-Compatibility-Functions.html#g-win32-check-windows-version

With regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|