How to determine Windows version in future-proof way - c

Question

I noticed that GetVersionEx() is declared deprecated. Worse yet, for Windows 8.1 (and presumably future releases) the version number is limited by the application manifest.
My goal is to collect analytics on operating systems which the users are running, so I can appropriately target support. I would like a future-proof solution for collecting this data. Updating the manifest won't work because I can only update the manifest for Windows versions which have already been released, not for future versions. The suggested replacement API, the version helper functions, is useless.
How can I collect the actual Windows version number?
To clarify: By "future proofing", I just mean that I want something that has a reasonably good chance of working on the next version of Windows. Nothing is certain, but the docs do say that GetVersionEx() won't work.

Answer 1

MSDN has an example showing how to use the (useless for your scenario) version helper functions, but in the introduction is the following:
To obtain the full version number for the operating system, call the GetFileVersionInfo function on one of the system DLLs, such as Kernel32.dll, then call VerQueryValue to obtain the \StringFileInfo\\ProductVersion subblock of the file version information.
As of right now, neither the GetFileVersionInfo nor VerQueryValue function are deprecated.
Example
This will extract the product version from kernel32.dll and print it to the console:
#pragma comment(lib, "version.lib")
static const wchar_t kernel32[] = L"\\kernel32.dll";
wchar_t *path = NULL;
void *ver = NULL, *block;
UINT n;
BOOL r;
DWORD versz, blocksz;
VS_FIXEDFILEINFO *vinfo;
path = malloc(sizeof(*path) * MAX_PATH);
if (!path)
abort();
n = GetSystemDirectory(path, MAX_PATH);
if (n >= MAX_PATH || n == 0 ||
n > MAX_PATH - sizeof(kernel32) / sizeof(*kernel32))
abort();
memcpy(path + n, kernel32, sizeof(kernel32));
versz = GetFileVersionInfoSize(path, NULL);
if (versz == 0)
abort();
ver = malloc(versz);
if (!ver)
abort();
r = GetFileVersionInfo(path, 0, versz, ver);
if (!r)
abort();
r = VerQueryValue(ver, L"\\", &block, &blocksz);
if (!r || blocksz < sizeof(VS_FIXEDFILEINFO))
abort();
vinfo = (VS_FIXEDFILEINFO *) block;
printf(
"Windows version: %d.%d.%d",
(int) HIWORD(vinfo->dwProductVersionMS),
(int) LOWORD(vinfo->dwProductVersionMS),
(int) HIWORD(vinfo->dwProductVersionLS));
free(path);
free(ver);

Answer 2

Yikes, the currently accepted answer is over-complicated. Here's how to get the version of the current windows (with build numbers) quickly and reliably without requiring manifests and other nonsense tricks. And works on Windows 2000 and newer (i.e. every version of Windows in existence).
Short answer: use RtlGetVersion.
Don't have the Windows Driver Development Kit? Then it's a little less simple than including the header and using the function. Here's how you do it both with and without the WDK.
With WDK, include:
// Required for RtlGetVersion()
#pragma comment(lib, "ntdll.lib")
#include <Ntddk.h>
Without WDK, include:
// Required for RtlGetVersion()
#pragma comment(lib, "ntdll.lib")
// Define the function because we don't have the driver development
// kit headers. We could probably acquire them but it makes development
// onboarding a pain in the ass for new employees.
extern "C" {
typedef LONG NTSTATUS, *PNTSTATUS;
#define STATUS_SUCCESS (0x00000000)
// Windows 2000 and newer
NTSYSAPI NTSTATUS NTAPI RtlGetVersion(PRTL_OSVERSIONINFOEXW lpVersionInformation);
}
Now, simply get the accurate version details:
RTL_OSVERSIONINFOEXW osVers;
osVers.dwOSVersionInfoSize = sizeof(osVers);
// fill the structure with version details
NTSTATUS status = RtlGetVersion(&osVers);
// this should always succeed
assert(status == STATUS_SUCCESS);
The osVers variable now contains the accurate major, minor, and build number. No need to read file versions and no need to dynamically load libraries at runtime.
Please vote this above the other answer so this correct code can be used in applications rather than the rube-goldberg other answer. Thanks.