Reorganize `mrb_string_value_cstr` and related functions.

`mrb_string_value_cstr` and `mrb_string_value_len`: obsolete
`mrb_string_cstr`: new function to retrieve NULL terminated C string
`RSTRING_CSTR`: wrapper macro of `mrb_string_cstr`

2 files changed, 20 insertions, 10 deletions

diff --git a/src/class.c b/src/class.c
index ff55de0e6..5b190d28b 100644
--- a/src/class.c
+++ b/src/class.c
@@ -770,7 +770,7 @@ mrb_get_args(mrb_state *mrb, const char *format, ...)
         }
         if (i < argc) {
           ss = to_str(mrb, ARGV[arg_i++]);
-          *ps = mrb_string_value_cstr(mrb, &ss);
+          *ps = RSTRING_CSTR(mrb, ss);
           i++;
         }
       }
diff --git a/src/string.c b/src/string.c
index 71c6e126e..50c283593 100644
--- a/src/string.c
+++ b/src/string.c
@@ -1060,6 +1060,7 @@ mrb_str_to_str(mrb_state *mrb, mrb_value str)
   }
 }
 
+/* obslete: use RSTRING_PTR() */
 MRB_API const char*
 mrb_string_value_ptr(mrb_state *mrb, mrb_value str)
 {
@@ -1067,6 +1068,7 @@ mrb_string_value_ptr(mrb_state *mrb, mrb_value str)
   return RSTRING_PTR(str);
 }
 
+/* obslete: use RSTRING_LEN() */
 MRB_API mrb_int
 mrb_string_value_len(mrb_state *mrb, mrb_value ptr)
 {
@@ -2352,6 +2354,7 @@ mrb_cstr_to_inum(mrb_state *mrb, const char *str, mrb_int base, mrb_bool badchec
   return mrb_str_len_to_inum(mrb, str, strlen(str), base, badcheck);
 }
 
+/* obslete: use RSTRING_CSTR() or mrb_string_cstr() */
 MRB_API const char*
 mrb_string_value_cstr(mrb_state *mrb, mrb_value *ptr)
 {
@@ -2366,16 +2369,23 @@ mrb_string_value_cstr(mrb_state *mrb, mrb_value *ptr)
   if (p[len] == '\0') {
     return p;
   }
+  if (MRB_FROZEN_P(ps) || RSTR_CAPA(ps) == len) {
+    ps = str_new(mrb, NULL, len+1);
+    memcpy(RSTR_PTR(ps), p, len);
+    RSTR_SET_LEN(ps, len);
+    *ptr = mrb_obj_value(ps);
+  }
   else {
-    if (MRB_FROZEN_P(ps)) {
-      ps = str_new(mrb, p, len);
-      *ptr = mrb_obj_value(ps);
-    }
-    else {
-      mrb_str_modify(mrb, ps);
-    }
-    return RSTR_PTR(ps);
+    mrb_str_modify(mrb, ps);
   }
+  RSTR_PTR(ps)[len] = '\0';
+  return RSTR_PTR(ps);
+}
+
+MRB_API const char*
+mrb_string_cstr(mrb_state *mrb, mrb_value str)
+{
+  return mrb_string_value_cstr(mrb, &str);
 }
 
 MRB_API mrb_value
@@ -2489,7 +2499,7 @@ bad:
 MRB_API double
 mrb_str_to_dbl(mrb_state *mrb, mrb_value str, mrb_bool badcheck)
 {
-  return mrb_cstr_to_dbl(mrb, mrb_string_value_cstr(mrb, &str), badcheck);
+  return mrb_cstr_to_dbl(mrb, RSTRING_CSTR(mrb, str), badcheck);
 }
 
 /* 15.2.10.5.39 */