Refactor `mrb_cstr_to_dbl`; ref #4920

2 files changed, 58 insertions, 44 deletions

diff --git a/src/load.c b/src/load.c
index 4184c4753..e624c52d5 100644
--- a/src/load.c
+++ b/src/load.c
@@ -42,21 +42,17 @@ offset_crc_body(void)
 }
 
 #ifndef MRB_WITHOUT_FLOAT
+double mrb_str_len_to_dbl(mrb_state *mrb, const char *s, size_t len, mrb_bool badcheck);
+
 static double
 str_to_double(mrb_state *mrb, const char *p, size_t len)
 {
-  char buf[64];
-
   /* `i`, `inf`, `infinity` */
   if (len > 0 && p[0] == 'i') return INFINITY;
 
   /* `I`, `-inf`, `-infinity` */
   if (p[0] == 'I' || (len > 1 && p[0] == '-' && p[1] == 'i')) return -INFINITY;
-  mrb_assert(len < sizeof(buf));
-  strncpy(buf, p, len);
-  buf[len] = '\0';
-
-  return mrb_cstr_to_dbl(mrb, buf, TRUE);
+  return mrb_str_len_to_dbl(mrb, p, len, TRUE);
 }
 #endif
 
diff --git a/src/string.c b/src/string.c
index 08c14d8e8..15e52fb3c 100644
--- a/src/string.c
+++ b/src/string.c
@@ -2488,20 +2488,58 @@ mrb_str_to_i(mrb_state *mrb, mrb_value self)
 }
 
 #ifndef MRB_WITHOUT_FLOAT
-MRB_API double
-mrb_cstr_to_dbl(mrb_state *mrb, const char *s, mrb_bool badcheck)
+double
+mrb_str_len_to_dbl(mrb_state *mrb, const char *s, size_t len, mrb_bool badcheck)
 {
-  const char *p = s;
-  char *end;
   char buf[DBL_DIG * 4 + 10];
+  const char *p;
+  const char *pend = s + len;
+  char *end;
+  char *n;
+  char prev = 0;
   double d;
 
-  if (!p) return 0.0;
-  while (ISSPACE(*p)) p++;
+  if (!s) return 0.0;
+  while (ISSPACE(*s)) s++;
+  p = s;
 
   if (!badcheck && p[0] == '0' && (p[1] == 'x' || p[1] == 'X')) {
     return 0.0;
   }
+  while (p < pend) {
+    if (!*p) {
+      if (badcheck && p < pend) {
+        mrb_raise(mrb, E_ARGUMENT_ERROR, "string for Float contains null byte");
+        /* not reached */
+      }
+      pend = p;
+      p = s;
+      goto nocopy;
+    }
+    if (*p == '_') break;
+    p++;
+  }
+  p = s;
+  n = buf;
+  while (p < pend) {
+    char c = *p++;
+    if (c == '_') {
+      /* remove an underscore between digits */
+      if (n == buf || !ISDIGIT(prev) || p == pend) {
+        if (badcheck) goto bad;
+        break;
+      }
+    }
+    else if (badcheck && prev == '_' && !ISDIGIT(c)) goto bad;
+    else {
+      *n++ = c;
+    }
+    prev = c;
+  }
+  *n = '\0';
+  p = buf;
+  pend = n;
+nocopy:
   d = mrb_float_read(p, &end);
   if (p == end) {
     if (badcheck) {
@@ -2511,44 +2549,24 @@ bad:
     }
     return d;
   }
-  if (*end) {
-    char *n = buf;
-    char *e = buf + sizeof(buf) - 1;
-    char prev = 0;
-
-    while (p < end && n < e) prev = *n++ = *p++;
-    while (*p) {
-      if (*p == '_') {
-        /* remove an underscore between digits */
-        if (n == buf || !ISDIGIT(prev) || (++p, !ISDIGIT(*p))) {
-          if (badcheck) goto bad;
-          break;
-        }
-      }
-      prev = *p++;
-      if (n < e) *n++ = prev;
-    }
-    *n = '\0';
-    p = buf;
-
-    if (!badcheck && p[0] == '0' && (p[1] == 'x' || p[1] == 'X')) {
-      return 0.0;
-    }
-
-    d = mrb_float_read(p, &end);
-    if (badcheck) {
-      if (!end || p == end) goto bad;
-      while (*end && ISSPACE(*end)) end++;
-      if (*end) goto bad;
-    }
+  if (badcheck) {
+    if (!end || p == end) goto bad;
+    while (end<pend && ISSPACE(*end)) end++;
+    if (end<pend) goto bad;
   }
   return d;
 }
 
 MRB_API double
+mrb_cstr_to_dbl(mrb_state *mrb, const char *s, mrb_bool badcheck)
+{
+  return mrb_str_len_to_dbl(mrb, s, strlen(s), badcheck);
+}
+
+MRB_API double
 mrb_str_to_dbl(mrb_state *mrb, mrb_value str, mrb_bool badcheck)
 {
-  return mrb_cstr_to_dbl(mrb, RSTRING_CSTR(mrb, str), badcheck);
+  return mrb_str_len_to_dbl(mrb, RSTRING_PTR(str), RSTRING_LEN(str), badcheck);
 }
 
 /* 15.2.10.5.39 */