change sigar_net_interface_config_get to return sigar_net_interface_config_primary_get if name == NULL

src/os/darwin/darwin_sigar.c

@@ -1824,6 +1824,10 @@ int sigar_net_interface_config_get(sigar_t *sigar, const char *name,
     struct sockaddr_dl *sdl;
     struct ifreq ifr;
 
+    if (!name) {
+        return sigar_net_interface_config_primary_get(sigar, ifconfig);
+    }
+
     if (sigar->ifconf_len == 0) {
         if ((status = sigar_ifmsg_init(sigar)) != SIGAR_OK) {
             return status;

src/os/netware/netware_sigar.c

@@ -542,6 +542,10 @@ sigar_net_interface_config_get(sigar_t *sigar,
     INTERFACE_INFO *if_info = NULL;
     u_long flags;
 
+    if (!name) {
+        return sigar_net_interface_config_primary_get(sigar, ifconfig);
+    }
+
     /* win32 lacks socket ioctls to query given interface.
      * so we loop through the list to find our made up ifname.
      */

src/os/win32/win32_sigar.c

@@ -2446,6 +2446,10 @@ sigar_net_interface_config_get(sigar_t *sigar,
     MIB_IPADDRROW *ipaddr;
     int status;
 
+    if (!name) {
+        return sigar_net_interface_config_primary_get(sigar, ifconfig);
+    }
+
     status = get_mib_ifrow(sigar, name, &ifr);
     if (status != SIGAR_OK) {
         return status;

src/sigar.c

@@ -1468,6 +1468,10 @@ int sigar_net_interface_config_get(sigar_t *sigar, const char *name,
     int sock;
     struct ifreq ifr;
 
+    if (!name) {
+        return sigar_net_interface_config_primary_get(sigar, ifconfig);
+    }
+
     SIGAR_ZERO(ifconfig);
 
     if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {