exit.c

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#include <stdint.h>
#include <stdlib.h>
 
#include <syscall.h>
 
struct atexit_cb {
    struct atexit_cb *next;
    void (*cb)(void);
};
 
static uint64_t _atexit_count = 0;
static struct atexit_cb _atexits[32]; // POSIX requires at least 32 atexit functions
static struct atexit_cb *_atexit_last = NULL;
 
int
atexit(void (*function)(void))
{
    if (_atexit_count < 32) {
        struct atexit_cb *prev = _atexit_last;
 
        _atexits[_atexit_count].cb = function;
        _atexits[_atexit_count].next = prev;
 
        _atexit_last = &_atexits[_atexit_count];
        _atexit_count++;
    } else {
        // XXX: Support malloc
        return -1;
    }
 
    return 0;
}
 
void
exit(int status)
{
    while (_atexit_last != NULL) {
        (_atexit_last->cb)();
        _atexit_last = _atexit_last->next;
    }
 
    OSExit(status & 0x00ff);
 
    __builtin_unreachable();
}