/* * This test program will register the maximum number of exit functions * with atexit(). When this program exits, each exit function should get * called in the reverse order in which it was registered. (If the system * supports more than 25 exit functions, the function names will loop, but * the effect will be the same. Feel free to add more functions if desired) */ #include <stdio.h> #include <stdlib.h> typedef void (*vfuncp) (void); /* All functions call exit(), in order to test that exit functions can call * exit() without screwing everything up. :) */ #define make_exitfunc(num) \ __attribute__ ((__noreturn__)) static \ void exitfunc##num(void) \ { \ printf("Executing exitfunc"#num".\n"); \ exit(0); \ } make_exitfunc(0) make_exitfunc(1) make_exitfunc(2) make_exitfunc(3) make_exitfunc(4) make_exitfunc(5) make_exitfunc(6) make_exitfunc(7) make_exitfunc(8) make_exitfunc(9) make_exitfunc(10) make_exitfunc(11) make_exitfunc(12) make_exitfunc(13) make_exitfunc(14) make_exitfunc(15) make_exitfunc(16) make_exitfunc(17) make_exitfunc(18) make_exitfunc(19) make_exitfunc(20) make_exitfunc(21) make_exitfunc(22) make_exitfunc(23) make_exitfunc(24) static vfuncp func_table[] = { exitfunc0, exitfunc1, exitfunc2, exitfunc3, exitfunc4, exitfunc5, exitfunc6, exitfunc7, exitfunc8, exitfunc9, exitfunc10, exitfunc11, exitfunc12, exitfunc13, exitfunc14, exitfunc15, exitfunc16, exitfunc17, exitfunc18, exitfunc19, exitfunc20, exitfunc21, exitfunc22, exitfunc23, exitfunc24 }; /* glibc dynamically adds exit functions, so it will keep adding until * it runs out of memory! So this will limit the number of exit functions * we add in the loop below. uClibc has a set limit (currently 20), so the * loop will go until it can't add any more (so it should not hit this limit). */ #define ATEXIT_LIMIT 20 int main ( void ) { int i = 0; int count = 0; int numfuncs = sizeof(func_table)/sizeof(vfuncp); /* loop until no more can be added */ while(count < ATEXIT_LIMIT && atexit(func_table[i]) >= 0) { printf("Registered exitfunc%d with atexit()\n", i); count++; i = (i+1) % numfuncs; } printf("%d functions registered with atexit.\n", count); return 0; }