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#include <stddef.h> #include <stdlib.h> #include <limits.h> #include "libc.h" /* Ensure that at least 32 atexit handlers can be registered without malloc */ #define COUNT 32 static struct fl { struct fl *next; void (*f[COUNT])(void); } builtin, *head; static int run_atexit_functions(void) { int i; for (; head; head=head->next) { for (i=COUNT-1; i>=0 && !head->f[i]; i--); for (; i>=0; i--) head->f[i](); } return 0; } int (*const __funcs_on_exit)(void) = run_atexit_functions; int atexit(void (*func)(void)) { static int lock; int i; /* Hook for atexit extensions */ if (libc.atexit) return libc.atexit(func); LOCK(&lock); /* Defer initialization of head so it can be in BSS */ if (!head) head = &builtin; /* If the current function list is full, add a new one */ if (head->f[COUNT-1]) { struct fl *new_fl = calloc(sizeof(struct fl), 1); if (!new_fl) { UNLOCK(&lock); return -1; } new_fl->next = head; head = new_fl; } /* Append function to the list. */ for (i=0; i<COUNT && head->f[i]; i++); head->f[i] = func; UNLOCK(&lock); return 0; } |