gistfile1.txt

#include <windows.h>
#include <stdio.h>

static int v1, v2, v3, v4;

static BYTE zero_rbx_code[] = { 0x48, 0x31, 0xdb, 0xc3, };
static void* exec_mem;

void (WINAPI *zero_rbx)(void);

VOID WINAPI tls_callback1(
    PVOID DllHandle,
    DWORD Reason,
    PVOID Reserved)
{
    if (!zero_rbx)
    {
        void* exec_mem;
        exec_mem = VirtualAlloc(NULL, 0x1000, MEM_RESERVE | MEM_COMMIT, PAGE_EXECUTE_READWRITE);
        if (!exec_mem) printf("Error: VirtualAlloc failed.\n");
        memcpy(exec_mem, zero_rbx_code, sizeof(zero_rbx_code));
        zero_rbx = exec_mem;
    }

    if (Reason == DLL_PROCESS_ATTACH)
        v1 = 1;
    else if (Reason == DLL_THREAD_ATTACH)
        v3 = 10;
    printf("cb1 called, reason %u.\n", Reason);
    zero_rbx();
}

VOID WINAPI tls_callback2(
    PVOID DllHandle,
    DWORD Reason,
    PVOID Reserved)
{
    printf("cb2 called, reason %u.\n", Reason);

    if (Reason == DLL_PROCESS_ATTACH)
        v2 = 2;
    else if (Reason == DLL_THREAD_ATTACH)
        v4 = 20;
}

//-------------------------------------------------------------------------
// TLS 32/64 bits example by Elias Bachaalany <lallousz-x86@yahoo.com>
#ifdef _M_AMD64
    #pragma comment (linker, "/INCLUDE:_tls_used")
    #pragma comment (linker, "/INCLUDE:p_tls_callback1")
    #pragma comment (linker, "/INCLUDE:p_tls_callback2")
#pragma const_seg(push)
    #pragma const_seg(".CRT$XLAAA")
        EXTERN_C const PIMAGE_TLS_CALLBACK p_tls_callback1 = tls_callback1;
    #pragma const_seg(".CRT$XLAAB")
        EXTERN_C const PIMAGE_TLS_CALLBACK p_tls_callback2 = tls_callback2;
    #pragma const_seg(pop)
#endif
#ifdef _M_IX86
    #pragma comment (linker, "/INCLUDE:__tls_used")
    #pragma comment (linker, "/INCLUDE:_p_tls_callback1")
    #pragma data_seg(push)
    #pragma data_seg(".CRT$XLAAA")
        EXTERN_C PIMAGE_TLS_CALLBACK p_tls_callback1 = tls_callback1;
    #pragma data_seg(".CRT$XLAAB")
        EXTERN_C PIMAGE_TLS_CALLBACK p_tls_callback2 = tls_callback2;
    #pragma data_seg(pop)
#endif

static DWORD WINAPI thread_proc(void* dummy)
{
    return 0;
}
//-------------------------------------------------------------------------
int main(int argc, char* argv[])
{
    HANDLE thread;
    thread = CreateThread(NULL, 0, thread_proc, NULL, 0, NULL);
    WaitForSingleObject(thread, INFINITE);
    printf("%d, %d, %d, %d\n", v1, v2, v3, v4);
    return 0;
}