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Date: Thu, 23 Jul 2015 01:44:06 +0200
From: Szabolcs Nagy <>
Subject: [PATCH] fix atexit when it is called from an atexit handler

When running atexit handlers always restart iterating the list of
handlers so if new ones are registered they are called in the right

Note that the iteration changes the head pointer in an irreversible
way, this is not a problem, but may cause more allocations than
optimal when new handlers are registered during exit.

The old code accepted atexit handlers after exit, but did not run
them.  C11 seems to explicitly allow atexit to fail in this case,
but this situation can easily come up in C++ if a destructor has
local static object with a destructor so it should be handled.
 src/exit/atexit.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/exit/atexit.c b/src/exit/atexit.c
index be82718..a0fd8d7 100644
--- a/src/exit/atexit.c
+++ b/src/exit/atexit.c
@@ -14,13 +14,24 @@ static struct fl
 static volatile int lock[2];
+static int next()
+	int i;
+	for (; head; head=head->next)
+		for (i=COUNT-1; i>=0; i--)
+			if (head->f[i])
+				return i;
+	return -1;
 void __funcs_on_exit()
 	int i;
 	void (*func)(void *), *arg;
-	for (; head; head=head->next) for (i=COUNT-1; i>=0; i--) {
-		if (!head->f[i]) continue;
+	for (;;) {
+		i = next();
+		if (i<0) break;
 		func = head->f[i];
 		arg = head->a[i];
 		head->f[i] = 0;

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