ref: e43e3872b43d9c1b49e9e5c015b32258c3735ad8
dir: /src/libc/stdlib/atexit.c/
#include <stdlib.h>
#include <errno.h>
#undef atexit
int
atexit(void (*fun)(void))
{
if (_exitn == _ATEXIT_MAX) {
errno = ENOMEM;
return -1;
}
_exitf[_exitn++] = fun;
return 0;
}