implicit_tls.c

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/*
 * PROJECT:     ReactOS API Tests
 * LICENSE:     MIT (https://spdx.org/licenses/MIT)
 * PURPOSE:     Tests for Implicit Thread Local Storage (TLS) support
 * COPYRIGHT:   Copyright 2025 Shane Fournier <shanefournier@yandex.com>
 */
 
#define WIN32_NO_STATUS
#define _INC_WINDOWS
#define COM_NO_WINDOWS_H
 
#include <ndk/ntndk.h>
#include <windows.h>
 
#if defined(_MSC_VER)
#define _CRTALLOC(x) __declspec(allocate(x))
#elif defined(__GNUC__)
#define _CRTALLOC(x) __attribute__ ((section (x) ))
#else
#error Your compiler is not supported.
#endif
 
/* 
 * Putting this note here as this is more directly related to TLS:
 * https://web.archive.org/web/20250204223245/http://www.nynaeve.net/?tag=tls
 */
/* Tls magic stolen from sdk/lib/crt/startup/tlssup.c */
/* ROS is built with the flag /Zc:threadSafeInit- which prevents the compilation
 * of proper TLS code. Instead, hack up a TLS directory to increment the TLS index
 * and allow the loader to allocate a sufficient buffer in the TLS vector. */
 
#if defined(_MSC_VER)
#pragma section(".rdata$T",long,read)
#pragma section(".tls",long,read,write)
#pragma section(".tls$ZZZ",long,read,write)
#endif
 
_CRTALLOC(".tls") char _tls_start = 0;
_CRTALLOC(".tls$ZZZ") char _tls_end = 0;
 
ULONG _tls_index = 0;
 
_CRTALLOC(".rdata$T") const IMAGE_TLS_DIRECTORY _tls_used = {
  (ULONG_PTR) &_tls_start, (ULONG_PTR) &_tls_end + 3,
  (ULONG_PTR) &_tls_index, (ULONG_PTR) 0,
  (ULONG) 0, (ULONG) 0
};
 
BOOL WINAPI
DllMain(IN HINSTANCE hDllHandle,
        IN DWORD dwReason,
        IN LPVOID lpvReserved)
{
    PTEB Teb = NtCurrentTeb();
    PVOID* TlsVector = Teb->ThreadLocalStoragePointer;
    PULONG_PTR ModuleHandle = (PULONG_PTR)TlsVector[_tls_index];
    if (dwReason == DLL_PROCESS_ATTACH)
    {
        #if defined(_MSC_VER)
        #pragma warning( disable : 4311)
        #endif
        *ModuleHandle = (ULONG_PTR)GetModuleHandleA(NULL) + 1;
    }
    return TRUE;
}