From 16e25b2890927108ec15297aabb1d86a49792741 Mon Sep 17 00:00:00 2001
From: Stef Walter <stefw@redhat.com>
Date: Fri, 3 Oct 2014 09:42:27 +0200
Subject: p11-kit: Use pthread_atfork() in a safe manner

Instead of trying to perform actions in pthread_atfork() which
are not async-signal-safe, just increment a counter so we can
later tell if the process has forked.

Note this does not make it safe to mix threads and forking without
immediately execing. This is a far broader problem that p11-kit,
however we now do the right thing when fork+exec is used from a
thread.

https://bugs.freedesktop.org/show_bug.cgi?id=84567
---
 common/library.c | 11 +++++++++++
 common/library.h |  2 ++
 common/mock.c    |  1 +
 3 files changed, 14 insertions(+)

(limited to 'common')

diff --git a/common/library.c b/common/library.c
index b7d6923..502ea98 100644
--- a/common/library.c
+++ b/common/library.c
@@ -63,6 +63,8 @@ p11_mutex_t p11_library_mutex;
 pthread_once_t p11_library_once = PTHREAD_ONCE_INIT;
 #endif
 
+unsigned int p11_forkid = 1;
+
 static char *
 thread_local_message (void)
 {
@@ -103,6 +105,13 @@ _p11_library_get_thread_local (void)
 	return local;
 }
 
+static void
+count_forks (void)
+{
+	/* Thread safe, executed in child, one thread exists */
+	p11_forkid++;
+}
+
 void
 p11_library_init_impl (void)
 {
@@ -111,6 +120,8 @@ p11_library_init_impl (void)
 	p11_mutex_init (&p11_library_mutex);
 	pthread_key_create (&thread_local, free);
 	p11_message_storage = thread_local_message;
+
+	pthread_atfork (NULL, NULL, count_forks);
 }
 
 void
diff --git a/common/library.h b/common/library.h
index 33a33fb..f87494d 100644
--- a/common/library.h
+++ b/common/library.h
@@ -44,6 +44,8 @@
 
 extern p11_mutex_t p11_library_mutex;
 
+extern unsigned int p11_forkid;
+
 #define       p11_lock()                   p11_mutex_lock (&p11_library_mutex);
 
 #define       p11_unlock()                 p11_mutex_unlock (&p11_library_mutex);
diff --git a/common/mock.c b/common/mock.c
index 01e095d..a73ae9d 100644
--- a/common/mock.c
+++ b/common/mock.c
@@ -46,6 +46,7 @@
 #include "debug.h"
 #include "dict.h"
 #include "array.h"
+#include "library.h"
 
 #include <assert.h>
 #include <ctype.h>
-- 
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