dll.c

/*
 * dll.c
 *
 * Description:
 * This translation unit implements DLL initialisation.
 * This translation unit implements static auto-init and auto-exit logic.
 *
 * --------------------------------------------------------------------------
 *
 *      pthreads-win32 - POSIX Threads Library for Win32
 *      Copyright(C) 1998 John E. Bossom
 *      Copyright(C) 1999-2021 pthreads-win32 / pthreads4w contributors
 *
 *      Homepage1: http://sourceware.org/pthreads-win32/
 *      Homepage2: http://sourceforge.net/projects/pthreads4w/
 *
 *      The current list of contributors is contained
 *      in the file CONTRIBUTORS included with the source
 *      code distribution. The list can also be seen at the
 *      following World Wide Web location:
 *      http://sources.redhat.com/pthreads-win32/contributors.html
 * 
 *      This library is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU Lesser General Public
 *      License as published by the Free Software Foundation; either
 *      version 2 of the License, or (at your option) any later version.
 * 
 *      This library is distributed in the hope that it will be useful,
 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *      Lesser General Public License for more details.
 * 
 *      You should have received a copy of the GNU Lesser General Public
 *      License along with this library in the file COPYING.LIB;
 *      if not, write to the Free Software Foundation, Inc.,
 *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 *
 * --------------------------------------------------------------------------
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#if defined(PTW32_STATIC_LIB) && defined(_MSC_VER) && _MSC_VER >= 1400 && defined(_WINDLL)
#  undef PTW32_STATIC_LIB
#  define PTW32_STATIC_TLSLIB
#endif

/* [i_a] sanity build checks */
#if defined(_MSC_VER) && (defined(_WIN32) || defined(_WIN64))
#if   !defined(PTW32_STATIC_LIB) && !defined(_WINDLL)
#error "Should not compile dynamic library code when apparently trying to build a static lib"
#elif  defined(PTW32_STATIC_LIB) &&  defined(_WINDLL)
#error "Should not compile static library code when apparently trying to build a dynamic lib DLL"
#endif
#endif

#include "pthread.h"
#include "implement.h"

#if !defined(PTW32_STATIC_LIB)

#if defined(_MSC_VER)
/*
 * lpvReserved yields an unreferenced formal parameter;
 * ignore it
 */
#pragma warning( disable : 4100 )
#endif

PTW32_BEGIN_C_DECLS

BOOL WINAPI DllMain (HINSTANCE hinstDll, DWORD fdwReason, LPVOID lpvReserved)
{
  BOOL result = PTW32_TRUE;

  switch (fdwReason)
    {

    case DLL_PROCESS_ATTACH:
      result = pthread_win32_process_attach_np ();
      break;

    case DLL_THREAD_ATTACH:
      /*
       * A thread is being created
       */
      result = pthread_win32_thread_attach_np ();
      break;

    case DLL_THREAD_DETACH:
      /*
       * A thread is exiting cleanly
       */
      result = pthread_win32_thread_detach_np ();
      break;

    case DLL_PROCESS_DETACH:
      (void) pthread_win32_thread_detach_np ();
      result = pthread_win32_process_detach_np ();
      break;
    }

  return (result);
}				/* DllMain */

PTW32_END_C_DECLS

#endif /* !PTW32_STATIC_LIB */

#if ! defined(PTW32_BUILD_INLINED)
/*
 * Avoid "translation unit is empty" warnings
 */
typedef int foo;
#endif

/* Visual Studio 8+ can leverage PIMAGE_TLS_CALLBACK CRT segments, which
 * give a static lib its very own DllMain.
 */
#ifdef PTW32_STATIC_TLSLIB

static void WINAPI
TlsMain(PVOID h, DWORD r, PVOID u)
{
  (void)DllMain((HINSTANCE)h, r, u);
}

#ifdef _M_X64
# pragma comment (linker, "/INCLUDE:_tls_used")
# pragma comment (linker, "/INCLUDE:_xl_b")
# pragma const_seg(".CRT$XLB")
EXTERN_C const PIMAGE_TLS_CALLBACK _xl_b = TlsMain;
# pragma const_seg()
#else
# pragma comment (linker, "/INCLUDE:__tls_used")
# pragma comment (linker, "/INCLUDE:__xl_b")
# pragma data_seg(".CRT$XLB")
EXTERN_C PIMAGE_TLS_CALLBACK _xl_b = TlsMain;
# pragma data_seg()
#endif /* _M_X64 */

#endif /* PTW32_STATIC_TLSLIB */

#if defined(PTW32_STATIC_LIB)

/*
 * Note: MSVC 8 and higher use code in dll.c, which enables TLS cleanup
 * on thread exit. Code here can only do process init and exit functions.
 */

#if defined(__MINGW32__) || defined(_MSC_VER)

/* For an explanation of this code (at least the MSVC parts), refer to
 *
 * http://www.codeguru.com/cpp/misc/misc/threadsprocesses/article.php/c6945/
 * ("Running Code Before and After Main")
 *
 * Compatibility with MSVC8 was cribbed from Boost:
 *
 * http://svn.boost.org/svn/boost/trunk/libs/thread/src/win32/tss_pe.cpp
 *
 * In addition to that, because we are in a static library, and the linker
 * can't tell that the constructor/destructor functions are actually
 * needed, we need a way to prevent the linker from optimizing away this
 * module. The pthread_win32_autostatic_anchor() hack below (and in
 * implement.h) does the job in a portable manner.
 *
 * Make everything "extern" to evade being optimized away.
 * Yes, "extern" is implied if not "static" but we are indicating we are
 * doing this deliberately.
 */

extern int ptw32_on_process_init(void)
{
    pthread_win32_process_attach_np ();
    return 0;
}

extern int ptw32_on_process_exit(void)
{
    pthread_win32_thread_detach_np  ();
    pthread_win32_process_detach_np ();
    return 0;
}

#if defined(__GNUC__)
__attribute__((section(".ctors"), used)) extern int (*gcc_ctor)(void) = ptw32_on_process_init;
__attribute__((section(".dtors"), used)) extern int (*gcc_dtor)(void) = ptw32_on_process_exit;
#elif defined(_MSC_VER)
#  if _MSC_VER >= 1400 /* MSVC8+ */
#    pragma section(".CRT$XCU", long, read)
#    pragma section(".CRT$XPU", long, read)
__declspec(allocate(".CRT$XCU")) extern int (*msc_ctor)(void) = ptw32_on_process_init;
__declspec(allocate(".CRT$XPU")) extern int (*msc_dtor)(void) = ptw32_on_process_exit;
#  else
#    pragma data_seg(".CRT$XCU")
extern int (*msc_ctor)(void) = ptw32_on_process_init;
#    pragma data_seg(".CRT$XPU")
extern int (*msc_dtor)(void) = ptw32_on_process_exit;
#    pragma data_seg() /* reset data segment */
#  endif
#endif

#endif /* defined(__MINGW32__) || defined(_MSC_VER) */

PTW32_BEGIN_C_DECLS

#if defined (PTW32_STATIC_LIB) && defined (PTW32_BUILD) && !defined (PTW32_TEST_SNEAK_PEEK)
/* This dummy function exists solely to be referenced by other modules
 * (specifically, in implement.h), so that the linker can't optimize away
 * this module. Don't call it.
 *
 * Shouldn't work if we are compiling via pthreads.c
 * (whole library single translation unit)
 * Leaving it here in case it affects small-static builds.
 */
void ptw32_autostatic_anchor(void) { abort(); }
#endif

PTW32_END_C_DECLS

#endif /*  PTW32_STATIC_LIB */