Subversion Repositories Kolibri OS

/*

 *  Common routine to implement atexit-like functionality.

 *

 *  This is also the key function to be configured as lite exit, a size-reduced

 *  implementation of exit that doesn't invoke clean-up functions such as _fini

 *  or global destructors.

 *

 *  Default (without lite exit) call graph is like:

 *  _start -> atexit -> __register_exitproc

 *  _start -> __libc_init_array -> __cxa_atexit -> __register_exitproc

 *  on_exit -> __register_exitproc

 *  _start -> exit -> __call_exitprocs

 *

 *  Here an -> means arrow tail invokes arrow head. All invocations here

 *  are non-weak reference in current newlib/libgloss.

 *

 *  Lite exit makes some of above calls as weak reference, so that size expansive

 *  functions __register_exitproc and __call_exitprocs may not be linked. These

 *  calls are:

 *    _start w-> atexit

 *    __cxa_atexit w-> __register_exitproc

 *    exit w-> __call_exitprocs

 *

 *  Lite exit also makes sure that __call_exitprocs will be referenced as non-weak

 *  whenever __register_exitproc is referenced as non-weak.

 *

 *  Thus with lite exit libs, a program not explicitly calling atexit or on_exit

 *  will escape from the burden of cleaning up code. A program with atexit or on_exit

 *  will work consistently to normal libs.

 *

 *  Lite exit is enabled with --enable-lite-exit, and is controlled with macro

 *  _LITE_EXIT.

 */

#include 

#include 

#include 

#include 

#include "atexit.h"

/* Make this a weak reference to avoid pulling in malloc.  */

void * malloc(size_t) _ATTRIBUTE((__weak__));

#ifdef _LITE_EXIT

/* As __call_exitprocs is weak reference in lite exit, make a

   non-weak reference to it here.  */

const void * __atexit_dummy = &__call_exitprocs;

#endif

#ifndef __SINGLE_THREAD__

extern _LOCK_RECURSIVE_T __atexit_lock;

#endif

#ifdef _REENT_GLOBAL_ATEXIT

static struct _atexit _global_atexit0 = _ATEXIT_INIT;

# define _GLOBAL_ATEXIT0 (&_global_atexit0)

#else

# define _GLOBAL_ATEXIT0 (&_GLOBAL_REENT->_atexit0)

#endif

/*

 * Register a function to be performed at exit or on shared library unload.

 */

int

_DEFUN (__register_exitproc,

	(type, fn, arg, d),

	int type _AND

	void (*fn) (void) _AND

	void *arg _AND

	void *d)

{

  struct _on_exit_args * args;

  register struct _atexit *p;

#ifndef __SINGLE_THREAD__

  __lock_acquire_recursive(__atexit_lock);

#endif

  p = _GLOBAL_ATEXIT;

  if (p == NULL)

    {

      _GLOBAL_ATEXIT = p = _GLOBAL_ATEXIT0;

#ifdef _REENT_SMALL

      extern struct _on_exit_args * const __on_exit_args _ATTRIBUTE ((weak));

      if (&__on_exit_args != NULL)

	p->_on_exit_args_ptr = __on_exit_args;

#endif	/* def _REENT_SMALL */

    }

  if (p->_ind >= _ATEXIT_SIZE)

    {

#ifndef _ATEXIT_DYNAMIC_ALLOC

#ifndef __SINGLE_THREAD__

      __lock_release_recursive(__atexit_lock);

#endif

      return -1;

#else

      /* Don't dynamically allocate the atexit array if malloc is not

	 available.  */

      if (!malloc)

	{

#ifndef __SINGLE_THREAD__

	  __lock_release_recursive(__atexit_lock);

#endif

	  return -1;

	}

      p = (struct _atexit *) malloc (sizeof *p);

      if (p == NULL)

	{

#ifndef __SINGLE_THREAD__

	  __lock_release_recursive(__atexit_lock);

#endif

	  return -1;

	}

      p->_ind = 0;

      p->_next = _GLOBAL_ATEXIT;

      _GLOBAL_ATEXIT = p;

#ifndef _REENT_SMALL

      p->_on_exit_args._fntypes = 0;

      p->_on_exit_args._is_cxa = 0;

#else

      p->_on_exit_args_ptr = NULL;

#endif

#endif

    }

  if (type != __et_atexit)

    {

#ifdef _REENT_SMALL

      args = p->_on_exit_args_ptr;

      if (args == NULL)

	{

#ifndef _ATEXIT_DYNAMIC_ALLOC

#ifndef __SINGLE_THREAD__

	  __lock_release_recursive(__atexit_lock);

#endif

	  return -1;

#else

	  if (malloc)

	    args = malloc (sizeof * p->_on_exit_args_ptr);

	  if (args == NULL)

	    {

#ifndef __SINGLE_THREAD__

	      __lock_release(__atexit_lock);

#endif

	      return -1;

	    }

	  args->_fntypes = 0;

	  args->_is_cxa = 0;

	  p->_on_exit_args_ptr = args;

#endif

	}

#else

      args = &p->_on_exit_args;

#endif

      args->_fnargs[p->_ind] = arg;

      args->_fntypes |= (1 << p->_ind);

      args->_dso_handle[p->_ind] = d;

      if (type == __et_cxa)

	args->_is_cxa |= (1 << p->_ind);

    }

  p->_fns[p->_ind++] = fn;

#ifndef __SINGLE_THREAD__

  __lock_release_recursive(__atexit_lock);

#endif

  return 0;

}