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Merge pull request #2971 from ZMQers/fix-static-init

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Problem: static initialization order fiasco
This commit is contained in:
Luca Boccassi
2018-03-06 09:18:52 +00:00
committed by GitHub
parent 494c2a71f8 8cdfc8b9dd
commit 10d2b2885e
1 changed files with 57 additions and 22 deletions
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79
src/random.cpp
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@@ -79,41 +79,76 @@ uint32_t zmq::generate_random ()
// The context class cannot be used with static variables as the curve
// utility APIs like zmq_curve_keypair also call into the crypto
// library.
// The safest solution for all use cases therefore is to have a global,
// The safest solution for all use cases therefore is to have a
// static lock to serialize calls into an initialiser and a finaliser,
// using refcounts to make sure that a thread does not close the library
// while another is still using it.
// while another is still using it. To avoid the static initialization
// order fiasco, this is done using function-local statics, if the
// compiler implementation supports thread-safe initialization of those.
// Otherwise, we fall back to global statics.
// TODO if there is some other user of libsodium besides libzmq, this must
// be synchronized by the application. This should probably also be
// configurable via config.h
// TODO this should probably be done via config.h
#if __cplusplus >= 201103L \
|| (defined(__cpp_threadsafe_static_init) \
&& __cpp_threadsafe_static_init >= 200806) \
|| (defined(_MSC_VER) && _MSC_VER >= 1900)
#define ZMQ_HAVE_THREADSAFE_STATIC_LOCAL_INIT 1
// TODO this might probably also be set if a sufficiently recent gcc is used
// without -fno-threadsafe-statics, but this cannot be determined at
// compile-time, so it must be set via config.h
#else
#define ZMQ_HAVE_THREADSAFE_STATIC_LOCAL_INIT 0
#endif
#if !ZMQ_HAVE_THREADSAFE_STATIC_LOCAL_INIT \
&& (defined(ZMQ_USE_LIBSODIUM) \
|| (defined(ZMQ_USE_TWEETNACL) && !defined(ZMQ_HAVE_WINDOWS) \
&& !defined(ZMQ_HAVE_GETRANDOM)))
static unsigned int random_refcount = 0;
static zmq::mutex_t random_sync;
#endif
void zmq::random_open (void)
static void manage_random (bool init)
{
#if defined(ZMQ_USE_LIBSODIUM) \
|| (defined(ZMQ_USE_TWEETNACL) && !defined(ZMQ_HAVE_WINDOWS) \
&& !defined(ZMQ_HAVE_GETRANDOM))
scoped_lock_t locker (random_sync);
if (random_refcount == 0) {
int rc = sodium_init ();
zmq_assert (rc != -1);
}
++random_refcount;
#else
LIBZMQ_UNUSED (random_refcount);
#if ZMQ_HAVE_THREADSAFE_STATIC_LOCAL_INIT
static int random_refcount = 0;
static zmq::mutex_t random_sync;
#endif
if (init) {
zmq::scoped_lock_t locker (random_sync);
if (random_refcount == 0) {
int rc = sodium_init ();
zmq_assert (rc != -1);
}
++random_refcount;
} else {
zmq::scoped_lock_t locker (random_sync);
--random_refcount;
if (random_refcount == 0) {
randombytes_close ();
}
}
#endif
}
void zmq::random_open (void)
{
manage_random (true);
}
void zmq::random_close (void)
{
#if defined(ZMQ_USE_LIBSODIUM) \
|| (defined(ZMQ_USE_TWEETNACL) && !defined(ZMQ_HAVE_WINDOWS) \
&& !defined(ZMQ_HAVE_GETRANDOM))
scoped_lock_t locker (random_sync);
--random_refcount;
if (random_refcount == 0) {
randombytes_close ();
}
#endif
manage_random (false);
}