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; }