WIP. Check for NULL

src/core/lib/iomgr/fork_posix.cc

@@ -59,8 +59,9 @@ void grpc_prefork() {
             "environment variable GRPC_ENABLE_FORK_SUPPORT=1");
     return;
   }
-  if (strcmp(grpc_get_poll_strategy_name(), "epoll1") != 0 &&
+  const char * poll_strategy_name = grpc_get_poll_strategy_name();
-      strcmp(grpc_get_poll_strategy_name(), "poll") != 0) {
+  if (poll_strategy_name == nullptr || strcmp(poll_strategy_name, "epoll1") != 0 &&
+      strcmp(poll_strategy_name, "poll") != 0) {
     gpr_log(GPR_INFO,
             "Fork support is only compatible with the epoll1 and poll polling "
             "strategies");