Avoid SIGPIPE on OS X without MSG_NOSIGNAL

OS X does not have Linux-specific option MSG_NOSIGNAL.
SIGPIPE can be avoided on OS X by using sockopt SO_NOSIGPIPE.
Credits: https://noahdesu.github.io/2014/01/16/port-sendmsg.html

include/tcpdefines.h

@@ -0,0 +1,27 @@
+#pragma once
+
+/**
+ * No MSG_NOSIGNAL on OS X.
+ * Avoid SIGPIPE by using sockopt call.
+ */
+#ifdef MSG_NOSIGNAL
+# define AMQP_CPP_MSG_NOSIGNAL MSG_NOSIGNAL
+#else
+# define AMQP_CPP_MSG_NOSIGNAL 0
+# ifdef SO_NOSIGPIPE
+#  define AMQP_CPP_USE_SO_NOSIGPIPE
+# else
+#  error "Cannot block SIGPIPE!"
+# endif
+#endif
+
+#ifdef AMQP_CPP_USE_SO_NOSIGPIPE
+/**
+ * Ignore SIGPIPE when there is no MSG_NOSIGNAL.
+ */
+inline void set_sockopt_nosigpipe(int socket)
+{
+    int optval = 1;
+    setsockopt(socket, SOL_SOCKET, SO_NOSIGPIPE, &optval, sizeof(optval));
+}
+#endif

src/includes.h

@@ -40,6 +40,7 @@
 #include "../include/outbuffer.h"
 #include "../include/watchable.h"
 #include "../include/monitor.h"
+#include "../include/tcpdefines.h"
 
 // amqp types
 #include "../include/field.h"

src/tcpconnected.h

@@ -189,7 +189,7 @@ public:
         if (_out) return _out.add(buffer, size);
 
         // there is no buffer, send the data right away
-        auto result = ::send(_socket, buffer, size, MSG_NOSIGNAL);
+        auto result = ::send(_socket, buffer, size, AMQP_CPP_MSG_NOSIGNAL);
 
         // number of bytes sent
         size_t bytes = result < 0 ? 0 : result;

src/tcpoutbuffer.h

@@ -236,7 +236,7 @@ public:
             header.msg_iovlen = index;
 
             // send the data
-            auto result = sendmsg(socket, &header, MSG_NOSIGNAL);
+            auto result = sendmsg(socket, &header, AMQP_CPP_MSG_NOSIGNAL);
 
             // skip on error, or when nothing was written
             if (result <= 0) return total > 0 ? total : result;

src/tcpresolver.h

@@ -120,6 +120,10 @@ private:
                 
                 // set the option
                 setsockopt(_socket, IPPROTO_TCP, TCP_NODELAY, &optval, sizeof(int));
+
+#ifdef AMQP_CPP_USE_SO_NOSIGPIPE
+                set_sockopt_nosigpipe(_socket);
+#endif
             }
         }
         catch (const std::runtime_error &error)