newlib/libc/stdlib/on_exit_args.c

   1 /*
   2  * Static instance of _on_exit_args struct.
   3  *
   4  * When _REENT_SMALL is used, _atexit struct only contains a pointer to
   5  * _on_exit_args struct, so this was always allocated with malloc() - even for
   6  * the first 32 calls of atexit()-like functions, which are guaranteed to
   7  * succeed, but could fail because of "out of memory" error. This is even worse
   8  * when _ATEXIT_DYNAMIC_ALLOC is _NOT_ defined, in which case malloc() is not
   9  * used by internals of atexit()-like functions. In such configuration all calls
  10  * to the functions that need _on_exit_args struct (on_exit() and
  11  * __cxa_atexit()) would fail.
  12  *
  13  * Thats why a static instance of _on_exit_args struct is provided for
  14  * _REENT_SMALL configuration. This way the first 32 calls to atexit()-like
  15  * functions don't need malloc() and will always succeed.
  16  *
  17  * Because this struct is not needed for "normal" atexit(), it is used as a weak
  18  * reference in __register_exitproc(), but any use of on_exit() or
  19  * __cxa_atexit() will force it to be linked.
  20  */
  21
  22 #include <reent.h>
  23
  24 #ifdef _REENT_SMALL
  25
  26 static struct _on_exit_args _on_exit_args_instance = {{_NULL}, {_NULL}, 0, 0};
  27
  28 struct _on_exit_args * const __on_exit_args = &_on_exit_args_instance;
  29
  30 #endif  /* def _REENT_SMALL */