Don't call memcpy with 0 size and NULL pointer(s)

It's undefined behavior, and ubsan flags it.

src/dealer.cpp

@@ -70,7 +70,8 @@ int zmq::dealer_t::xsetsockopt (int option_, const void *optval_,
     size_t optvallen_)
 {
     bool is_int = (optvallen_ == sizeof (int));
-    int value = is_int? *((int *) optval_): 0;
+    int value = 0;
+    if (is_int) memcpy(&value, optval_, sizeof (int));
 
     switch (option_) {
         case ZMQ_PROBE_ROUTER:

src/options.cpp

@@ -92,7 +92,8 @@ int zmq::options_t::setsockopt (int option_, const void *optval_,
     size_t optvallen_)
 {
     bool is_int = (optvallen_ == sizeof (int));
-    int value = is_int? *((int *) optval_): 0;
+    int value = 0;
+    if (is_int) memcpy(&value, optval_, sizeof (int));
 #if defined (ZMQ_ACT_MILITANT)
     bool malformed = true;          //  Did caller pass a bad option value?
 #endif

src/req.cpp

@@ -204,7 +204,8 @@ bool zmq::req_t::xhas_out ()
 int zmq::req_t::xsetsockopt (int option_, const void *optval_, size_t optvallen_)
 {
     bool is_int = (optvallen_ == sizeof (int));
-    int value = is_int? *((int *) optval_): 0;
+    int value = 0;
+    if (is_int) memcpy(&value, optval_, sizeof (int));
     switch (option_) {
         case ZMQ_REQ_CORRELATE:
             if (is_int && value >= 0) {

src/router.cpp

@@ -97,7 +97,8 @@ int zmq::router_t::xsetsockopt (int option_, const void *optval_,
     size_t optvallen_)
 {
     bool is_int = (optvallen_ == sizeof (int));
-    int value = is_int? *((int *) optval_): 0;
+    int value = 0;
+    if (is_int) memcpy(&value, optval_, sizeof (int));
 
     switch (option_) {
         case ZMQ_CONNECT_RID:

src/stream.cpp

@@ -178,7 +178,8 @@ int zmq::stream_t::xsetsockopt (int option_, const void *optval_,
     size_t optvallen_)
 {
     bool is_int = (optvallen_ == sizeof (int));
-    int value = is_int? *((int *) optval_): 0;
+    int value = 0;
+    if (is_int) memcpy(&value, optval_, sizeof (int));
     switch (option_) {
         case ZMQ_CONNECT_RID:
             if (optval_ && optvallen_) {

src/sub.cpp

@@ -62,7 +62,8 @@ int zmq::sub_t::xsetsockopt (int option_, const void *optval_,
     else
     if (option_ == ZMQ_UNSUBSCRIBE)
         *data = 0;
-    memcpy (data + 1, optval_, optvallen_);
+    if (optvallen_ > 0)
+        memcpy (data + 1, optval_, optvallen_);
 
     //  Pass it further on in the stack.
     int err = 0;

src/xsub.cpp

@@ -232,7 +232,8 @@ void zmq::xsub_t::send_subscription (unsigned char *data_, size_t size_,
     errno_assert (rc == 0);
     unsigned char *data = (unsigned char*) msg.data ();
     data [0] = 1;
-    memcpy (data + 1, data_, size_);
+    if (size_ > 0)
+        memcpy (data + 1, data_, size_);
 
     //  Send it to the pipe.
     bool sent = pipe->write (&msg);

src/zmq.cpp

@@ -393,7 +393,8 @@ int zmq_send (void *s_, const void *buf_, size_t len_, int flags_)
     int rc = zmq_msg_init_size (&msg, len_);
     if (rc != 0)
         return -1;
-    memcpy (zmq_msg_data (&msg), buf_, len_);
+    if (len_ > 0)
+        memcpy (zmq_msg_data (&msg), buf_, len_);
 
     zmq::socket_base_t *s = (zmq::socket_base_t *) s_;
     rc = s_sendmsg (s, &msg, flags_);
@@ -519,7 +520,8 @@ int zmq_recv (void *s_, void *buf_, size_t len_, int flags_)
     //  At the moment an oversized message is silently truncated.
     //  TODO: Build in a notification mechanism to report the overflows.
     size_t to_copy = size_t (nbytes) < len_ ? size_t (nbytes) : len_;
-    memcpy (buf_, zmq_msg_data (&msg), to_copy);
+    if (to_copy > 0)
+        memcpy (buf_, zmq_msg_data (&msg), to_copy);
 
     rc = zmq_msg_close (&msg);
     errno_assert (rc == 0);