From fc64ddc4b0d85b533bef98d8851464f470c2cb39 Mon Sep 17 00:00:00 2001
From: bcook <>
Date: Wed, 9 Jul 2014 14:26:59 +0000
Subject: check if we were previously on a signal stack before restoring.

OS X fails to restore the old signal stack because the signal stack is
not enabled by default. This causes sigaltstack(2) to fail with ENOMEM
as ss_size is 0, < MINSIGSTCKSZ.

ok jsing@
---
 src/regress/lib/libc/explicit_bzero/explicit_bzero.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/regress/lib/libc/explicit_bzero/explicit_bzero.c b/src/regress/lib/libc/explicit_bzero/explicit_bzero.c
index b4b6c9e559..d78c4d6054 100644
--- a/src/regress/lib/libc/explicit_bzero/explicit_bzero.c
+++ b/src/regress/lib/libc/explicit_bzero/explicit_bzero.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: explicit_bzero.c,v 1.1 2014/06/12 22:01:55 matthew Exp $	*/
+/*	$OpenBSD: explicit_bzero.c,v 1.2 2014/07/09 14:26:59 bcook Exp $	*/
 /*
  * Copyright (c) 2014 Google Inc.
  *
@@ -67,7 +67,8 @@ call_on_stack(void (*fn)(int), void *stack, size_t stacklen)
 
 	/* Restore the original signal action, stack, and mask. */
 	ASSERT_EQ(0, sigaction(SIGUSR1, &oldsigact, NULL));
-	ASSERT_EQ(0, sigaltstack(&oldsigstk, NULL));
+	if (oldsigstk.ss_flags & SA_ONSTACK)
+		ASSERT_EQ(0, sigaltstack(&oldsigstk, NULL));
 	ASSERT_EQ(0, sigprocmask(SIG_SETMASK, &oldsigset, NULL));
 }
 
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