remove invocation of strlen() on buffer of strings; with refactoring

include/mruby/string.h

@@ -47,6 +47,7 @@ struct RString {
    RSTRING_EMBED_LEN_MAX :\
    RSTRING(s)->as.heap.aux.capa)
 #define RSTRING_END(s)    (RSTRING_PTR(s) + RSTRING_LEN(s))
+mrb_int mrb_str_strlen(mrb_state*, struct RString*);
 
 #define MRB_STR_SHARED    1
 #define MRB_STR_NOFREE    2

src/class.c

@@ -534,25 +534,12 @@ mrb_get_args(mrb_state *mrb, const char *format, ...)
     case 'z':
       {
         mrb_value ss;
-        struct RString *s;
         char **ps;
-        mrb_int len;
 
         ps = va_arg(ap, char**);
         if (i < argc) {
-          size_t size_t_len;
           ss = to_str(mrb, *sp++);
-          s = mrb_str_ptr(ss);
-          size_t_len = strlen(RSTRING_PTR(ss));
-          mrb_assert(size_t_len <= MRB_INT_MAX);
-          len = (mrb_int)size_t_len;
-          if (len < RSTRING_LEN(ss)) {
-            mrb_raise(mrb, E_ARGUMENT_ERROR, "string contains null byte");
-          }
-          else if (len > RSTRING_LEN(ss)) {
-            mrb_str_modify(mrb, s);
-          }
-          *ps = RSTRING_PTR(ss);
+          *ps = mrb_string_value_cstr(mrb, &ss);
           i++;
         }
       }

src/string.c

@@ -54,6 +54,21 @@ typedef struct mrb_shared_string {
 static mrb_value str_replace(mrb_state *mrb, struct RString *s1, struct RString *s2);
 static mrb_value mrb_str_subseq(mrb_state *mrb, mrb_value str, mrb_int beg, mrb_int len);
 
+mrb_int
+mrb_str_strlen(mrb_state *mrb, struct RString *s)
+{
+  mrb_int i, max = STR_LEN(s);
+  char *p = STR_PTR(s);
+
+  if (!p) return 0;
+  for (i=0; i<max; i++) {
+    if (p[i] == '\0') {
+      mrb_raise(mrb, E_ARGUMENT_ERROR, "string contains null byte");
+    }
+  }
+  return max;
+}
+
 #define RESIZE_CAPA(s,capacity) do {\
   if (STR_EMBED_P(s)) {\
     if (RSTRING_EMBED_LEN_MAX < (capacity)) {\
@@ -2066,16 +2081,14 @@ char *
 mrb_string_value_cstr(mrb_state *mrb, mrb_value *ptr)
 {
   struct RString *ps = mrb_str_ptr(*ptr);
-  char *s = STR_PTR(ps);
-  mrb_int len;
+  mrb_int len = mrb_str_strlen(mrb, ps);
+  char *p = STR_PTR(ps);
 
-  len = STR_LEN(ps);
-  mrb_assert(len >= 0);
-  mrb_assert((size_t)len <= SIZE_MAX);
-  if (!s || (size_t)len != strlen(s)) {
-    mrb_raise(mrb, E_ARGUMENT_ERROR, "string contains null byte");
+  if (!p || p[len] != '\0') {
+    mrb_str_modify(mrb, ps);
+    return STR_PTR(ps);
   }
-  return s;
+  return p;
 }
 
 mrb_value