Avoid using `mrb_str_to_cstr` if possible

Because it always allocate new string. Replace with the followings:

- Use `RSRING_PTR` if string is guaranteed to be null-terminated.
- Use `mrb_string_value_cstr` or `mrb_get_args("z")` if return value isn't
  modified.

1 files changed, 2 insertions, 2 deletions

diff --git a/mrbgems/mruby-socket/src/socket.c b/mrbgems/mruby-socket/src/socket.c
index 2a8ae1b2c..8515a6057 100644
--- a/mrbgems/mruby-socket/src/socket.c
+++ b/mrbgems/mruby-socket/src/socket.c
@@ -131,7 +131,7 @@ mrb_addrinfo_getaddrinfo(mrb_state *mrb, mrb_value klass)
   mrb_get_args(mrb, "oo|oooi", &nodename, &service, &family, &socktype, &protocol, &flags);
 
   if (mrb_string_p(nodename)) {
-    hostname = mrb_str_to_cstr(mrb, nodename);
+    hostname = mrb_string_value_cstr(mrb, &nodename);
   } else if (mrb_nil_p(nodename)) {
     hostname = NULL;
   } else {
@@ -139,7 +139,7 @@ mrb_addrinfo_getaddrinfo(mrb_state *mrb, mrb_value klass)
   }
 
   if (mrb_string_p(service)) {
-    servname = mrb_str_to_cstr(mrb, service);
+    servname = mrb_string_value_cstr(mrb, &service);
   } else if (mrb_fixnum_p(service)) {
     servname = RSTRING_PTR(mrb_fixnum_to_str(mrb, service, 10));
   } else if (mrb_nil_p(service)) {