simplify atexit and fflush-on-exit handling

src/exit/atexit.c

@@ -12,18 +12,15 @@ static struct fl
 	void (*f[COUNT])(void);
 } builtin, *head;
 
-static int run_atexit_functions(void)
+void __funcs_on_exit()
 {
 	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;

src/exit/exit.c

@@ -3,8 +3,11 @@
 #include <stdio.h>
 #include "libc.h"
 
-/* __overflow.c and atexit.c override these */
-static int (*const dummy)() = 0;
+static void dummy()
+{
+}
+
+/* __towrite.c and atexit.c override these */
 weak_alias(dummy, __funcs_on_exit);
 weak_alias(dummy, __fflush_on_exit);
 
@@ -16,8 +19,8 @@ void exit(int code)
 	LOCK(&lock);
 
 	/* Only do atexit & stdio flush if they were actually used */
-	if (__funcs_on_exit) __funcs_on_exit();
-	if (__fflush_on_exit) __fflush_on_exit((void *)0);
+	__funcs_on_exit();
+	__fflush_on_exit();
 
 	/* Destructor s**t is kept separate from atexit to avoid bloat */
 	if (libc.fini) libc.fini();

src/stdio/__towrite.c

@@ -18,4 +18,7 @@ int __towrite(FILE *f)
 }
 
 /* Link flush-on-exit code iff any stdio write functions are linked. */
-int (*const __fflush_on_exit)(FILE *) = fflush;
+void __fflush_on_exit()
+{
+	fflush(0);
+}