ntdll/version.c

#include <windows.h>
#include <nt.h>

#define OSMajorVersion dwMajorVersion
#define OSMinorVersion dwMinorVersion
#define OSBuildNumber dwBuildNumber
#define OSPlatformId dwPlatformId

/*
typedef struct _RTL_OSVERSIONINFO {
	unsigned long int dwOSVersionInfoSize;
	unsigned long int dwMajorVersion;
	unsigned long int dwMinorVersion;
	unsigned long int dwBuildNumber;
	unsigned long int dwPlatformId;
} RTL_OSVERSIONINFO;
*/

unsigned long int _stdcall RtlGetVersion(RTL_OSVERSIONINFO *VersionInformation){
	PROCESS_BASIC_INFORMATION pbi;
	NtQueryInformationProcess((void *)-1, ProcessBasicInformation, &pbi, sizeof(pbi), NULL);
	PEB *peb = pbi.PebBaseAddress;
	VersionInformation->dwMajorVersion = peb->OSMajorVersion;
	VersionInformation->dwMinorVersion = peb->OSMinorVersion;
	VersionInformation->dwBuildNumber  = peb->OSBuildNumber;
	VersionInformation->dwPlatformId   = peb->OSPlatformId;
	return 0;
}