support __cxa_atexit, and registering atexit functions from atexit handlers

mildly tested; may have bugs. the locking should be updated not to use
spinlocks but that's outside the scope of this one module.

diff --git a/src/exit/atexit.c b/src/exit/atexit.c
index 6f00e374395501dcbb9b932eed4c070187ff53db..c613d85baef81a5d366e557a3b20384db4eed946 100644 (file)
--- a/src/exit/atexit.c
+++ b/src/exit/atexit.c
@@ -1,5 +1,6 @@
 #include <stddef.h>
 #include <stdlib.h>
+#include <stdint.h>
 #include <limits.h>
 #include "libc.h"
 
@@ -9,26 +10,33 @@
 static struct fl
 {
        struct fl *next;
-       void (*f[COUNT])(void);
+       void (*f[COUNT])(void *);
+       void *a[COUNT];
 } builtin, *head;
 
+static int lock;
+
 void __funcs_on_exit()
 {
        int i;
+       void (*func)(void *), *arg;
+       LOCK(&lock);
        for (; head; head=head->next) {
                for (i=COUNT-1; i>=0 && !head->f[i]; i--);
-               for (; i>=0; i--) head->f[i]();
+               if (i<0) continue;
+               func = head->f[i];
+               arg = head->a[i];
+               head->f[i] = 0;
+               UNLOCK(&lock);
+               func(arg);
+               LOCK(&lock);
        }
 }
 
-int atexit(void (*func)(void))
+int __cxa_atexit(void (*func)(void *), void *arg, void *dso)
 {
-       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 */
@@ -48,7 +56,18 @@ int atexit(void (*func)(void))
        /* Append function to the list. */
        for (i=0; i<COUNT && head->f[i]; i++);
        head->f[i] = func;
+       head->a[i] = arg;
 
        UNLOCK(&lock);
        return 0;
 }
+
+static void call(void *p)
+{
+       ((void (*)(void))(uintptr_t)p)();
+}
+
+int atexit(void (*func)(void))
+{
+       return __cxa_atexit(call, (void *)(uintptr_t)func, 0);
+}