Always call atexit handlers as if they were registered with __cxa_atexit.

The extra argument doesn't hurt genuine atexit handlers and this fixes a
bug where we didn't provide the argument (effectively passing garbage) for
functions registered with __cxa_atexit in the main executable.

Pointed out by Dmitriy Ivanov <dimitry@google.com> and Elliott Hughes
<enh@google.com>.

ok matthew@

3 files changed, 13 insertions, 19 deletions

diff --git a/src/lib/libc/stdlib/atexit.c b/src/lib/libc/stdlib/atexit.c
index 049da3261d..9b08ebd7e6 100644
--- a/src/lib/libc/stdlib/atexit.c
+++ b/src/lib/libc/stdlib/atexit.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: atexit.c,v 1.17 2013/12/28 18:38:42 kettenis Exp $ */
+/*      $OpenBSD: atexit.c,v 1.18 2014/06/18 19:01:10 kettenis Exp $ */
 /*
  * Copyright (c) 2002 Daniel Hartmeier
  * All rights reserved.
@@ -90,7 +90,7 @@ __cxa_atexit(void (*func)(void *), void *arg, void *dso)
                 __atexit = p;
         }
         fnp = &p->fns[p->ind++];
-        fnp->fn_ptr.cxa_func = func;
+        fnp->fn_ptr = func;
         fnp->fn_arg = arg;
         fnp->fn_dso = dso;
         if (mprotect(p, pgsize, PROT_READ))
@@ -118,7 +118,7 @@ __cxa_finalize(void *dso)
 
         for (p = __atexit; p != NULL; p = p->next) {
                 for (n = p->ind; --n >= 0;) {
-                        if (p->fns[n].fn_ptr.cxa_func == NULL)
+                        if (p->fns[n].fn_ptr == NULL)
                                 continue;       /* already called */
                         if (dso != NULL && dso != p->fns[n].fn_dso)
                                 continue;       /* wrong DSO */
@@ -129,13 +129,10 @@ __cxa_finalize(void *dso)
                          */
                         fn = p->fns[n];
                         if (mprotect(p, pgsize, PROT_READ | PROT_WRITE) == 0) {
-                                p->fns[n].fn_ptr.cxa_func = NULL;
+                                p->fns[n].fn_ptr = NULL;
                                 mprotect(p, pgsize, PROT_READ);
                         }
-                        if (fn.fn_dso != NULL)
-                                (*fn.fn_ptr.cxa_func)(fn.fn_arg);
-                        else
-                                (*fn.fn_ptr.std_func)();
+                        (*fn.fn_ptr)(fn.fn_arg);
                 }
         }
 
@@ -185,7 +182,7 @@ __atexit_register_cleanup(void (*func)(void))
                 if (mprotect(p, pgsize, PROT_READ | PROT_WRITE))
                         goto unlock;
         }
-        p->fns[0].fn_ptr.std_func = func;
+        p->fns[0].fn_ptr = (void (*)(void *))func;
         p->fns[0].fn_arg = NULL;
         p->fns[0].fn_dso = NULL;
         mprotect(p, pgsize, PROT_READ);
diff --git a/src/lib/libc/stdlib/atexit.h b/src/lib/libc/stdlib/atexit.h
index c44005deda..3de2aa3bf6 100644
--- a/src/lib/libc/stdlib/atexit.h
+++ b/src/lib/libc/stdlib/atexit.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: atexit.h,v 1.8 2013/06/02 21:08:36 matthew Exp $ */
+/*      $OpenBSD: atexit.h,v 1.9 2014/06/18 19:01:10 kettenis Exp $ */
 
 /*
  * Copyright (c) 2002 Daniel Hartmeier
@@ -35,10 +35,7 @@ struct atexit {
         int ind;                        /* next index in this table */
         int max;                        /* max entries >= ATEXIT_SIZE */
         struct atexit_fn {
-                union {
-                        void (*std_func)(void);
-                        void (*cxa_func)(void *);
-                } fn_ptr;
+                void (*fn_ptr)(void *);
                 void *fn_arg;           /* argument for CXA callback */
                 void *fn_dso;           /* shared module handle */
         } fns[1];                       /* the table itself */
diff --git a/src/regress/lib/libc/atexit/atexit_test.c b/src/regress/lib/libc/atexit/atexit_test.c
index 3dd0b62c3e..f374dee9eb 100644
--- a/src/regress/lib/libc/atexit/atexit_test.c
+++ b/src/regress/lib/libc/atexit/atexit_test.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: atexit_test.c,v 1.6 2007/09/03 14:42:44 millert Exp $ */
+/*      $OpenBSD: atexit_test.c,v 1.7 2014/06/18 19:01:10 kettenis Exp $ */
 
 /*
  * Copyright (c) 2002 Daniel Hartmeier
@@ -43,7 +43,7 @@
 void    handle_first(void);
 void    handle_middle(void);
 void    handle_last(void);
-void    handle_invalid(void);
+void    handle_invalid(void *);
 void    handle_cleanup(void);
 void    handle_signal(int);
 
@@ -79,7 +79,7 @@ main(int argc, char *argv[])
         /* this is supposed to segfault */
         if (!strcmp(argv[1], "-invalid-atexit")) {
                 signal(SIGSEGV, handle_signal);
-                __atexit->fns[0].fn_ptr.std_func = handle_invalid;
+                __atexit->fns[0].fn_ptr = handle_invalid;
         } else if (!strcmp(argv[1], "-invalid-cleanup")) {
                 struct atexit *p = __atexit;
 
@@ -88,7 +88,7 @@ main(int argc, char *argv[])
                         p = p->next;
                 if (p == NULL)
                         fprintf(stderr, "p == NULL, no page found\n");
-                p->fns[0].fn_ptr.std_func = handle_invalid;
+                p->fns[0].fn_ptr = handle_invalid;
         }
         __atexit_register_cleanup(handle_cleanup);
         counter = 0;
@@ -121,7 +121,7 @@ handle_cleanup(void)
 }
 
 void
-handle_invalid(void)
+handle_invalid(void *arg)
 {
         fprintf(stderr, "handle_invalid() THIS SHOULD HAVE SEGFAULTED INSTEAD!\n");
 }