Compiler errors with typedef c++

Question

I'm currently working on meshing together some declarations for ntdll functions from various exploit-db files in order to create a keylogger (educationally). I tried searching around on here, and the general web. I couldn't find anything similar enough to where I could understand how to use it to fix my issue. I apologize if there's a duplicate, I couldn't find anything related.

I put these in a header file, and when trying to compile them I get all sorts of errors related to the typedefs within the header, I get error messages mentioning decltype, and I'll admit I can't seem to understand it at all. I've never really messed with header stuff or with decltype, I searched around, but still can't really understand it. The errors occur with this:

typedef (NTSTATUS) (WINAPI *LPFUN_NtCreateThreadEx)
(
    OUT PHANDLE hThread,
    IN ACCESS_MASK DesiredAccess,
    IN LPVOID ObjectAttributes,
    IN HANDLE ProcessHandle,
    IN LPTHREAD_START_ROUTINE lpStartAddress,
    IN LPVOID lpParameter,
    IN BOOL CreateSuspended,
    IN DWORD StackZeroBits,
    IN DWORD SizeOfStackCommit,
    IN DWORD SizeOfStackReserve,
    OUT LPVOID lpBytesBuffer
);

typedef NTSTATUS(NTAPI *lNtAllocVirtMem)(
    IN  HANDLE  ProcessHandle,
    IN  PVOID   *BaseAddress,
    IN  PULONG  ZeroBits,
    IN  PSIZE_T RegionSize,
    IN  ULONG   AllocationType,
    IN  ULONG   Protect
);

The other error in the main.cpp is: (sorry about the long line)

lNtAllocVirtMem pNtAllocateVirtualMemory=(lNtAllocVirtMem)GetProcAddress(LoadLibaryA("ntdll.dll"),"NtAllocateVirtualMemory");

My errors are(I get a double of both):

error: expected primary-expression before '__attribute__'
error: typedef 'NTSTATUS' is initialized (use decltype instead)

I would like to know how to solve these (as I plan on adding more), and more importantly, how can I make sure I don't get these from here on out?

Answer 1

The type NTSTATUS is defined in the Windows SDK header file winternl.h :

typedef _Return_type_success_(return >= 0) LONG NTSTATUS;

You need to include that header file instead of trying to define NTSTATUS yourself. The SDK provided definition differs in two ways: 1 It contains SAL annotations that allow you do run static code analysis. 2 It provides the correct alias, irrespective of platform. It should be a 32-bit integer value on both x86 and x64 platforms. long may be longer than that.

Answer 2

The answer was incredibly simple. To the header I added:

typedef long NTSTATUS;

It seems to have compiled correctly, and one of the functions works fine from my understanding. I thank those who helped for sending me on the right thought process and in the right direction a TON :).

Edit: By using visual studios, i have access to winternl.h, where NTSTATUS is properly defined, my original answer is not a solution.