Install an ignore handler for SIGPIPE on *BSD to mimic MSG_NOSIGNAL

Original patch by Jason Oster

NEWS

@@ -1,6 +1,8 @@
 libmodbus 2.9.3 (2011-01-XX)
 ============================
 
+- Install an ignore handler for SIGPIPE on *BSD
+  Original patch by Jason Oster.
 - Fix closing of Win32 socket.
   Reported by Petr Parýzek.
 - Fix unit identifier not copied by the TCP server.

src/modbus-tcp.c

@@ -425,6 +425,19 @@ modbus_t* modbus_new_tcp(const char *ip, int port)
     modbus_t *ctx;
     modbus_tcp_t *ctx_tcp;
 
+#if defined(OS_BSD)
+    /* MSG_NOSIGNAL is unsupported on *BSD so we install an ignore
+       handler for SIGPIPE. */
+    struct sigaction sa;
+
+    sa.sa_handler = SIG_IGN;
+    if (sigaction(SIGPIPE, &sa, NULL) < 0) {
+        /* The debug flag can't be set here... */
+        fprintf(stderr, "Coud not install SIGPIPE handler.\n");
+        return -1;
+    }
+#endif
+
     ctx = (modbus_t *) malloc(sizeof(modbus_t));
     _modbus_init_common(ctx);