Fix dump/load float leteral evaluate to infinity

Example:

  # example.rb
  p(2e308)
  p(-2e308)

  Good:

    $ bin/mruby example.rb
    inf
    -inf

  Bad:

    $ bin/mrbc example.rb
    $ bin/mruby -b example.mrb
    0
    -0

Cause:

  Float infinity representation is `inf` on dump and it is converted by
  corresponding `String#to_f` on load.

Treatment:

  - Introduce new representations (`i`: +infinity, `I`: -infinity)
  - Allow old representations (`inf`, `-inf`, `infinity`, `-infinity`) too
  - Raise error for unknown representations (use corresponding `Kernel#Float`)

1 files changed, 19 insertions, 1 deletions

diff --git a/src/load.c b/src/load.c
index 559fff1d4..55e0845f3 100644
--- a/src/load.c
+++ b/src/load.c
@@ -7,6 +7,7 @@
 #include <limits.h>
 #include <stdlib.h>
 #include <string.h>
+#include <math.h>
 #include <mruby/dump.h>
 #include <mruby/irep.h>
 #include <mruby/proc.h>
@@ -40,6 +41,23 @@ offset_crc_body(void)
   return ((uint8_t *)header.binary_crc - (uint8_t *)&header) + sizeof(header.binary_crc);
 }
 
+#ifndef MRB_WITHOUT_FLOAT
+static double
+str_to_double(mrb_state *mrb, mrb_value str)
+{
+  const char *p = RSTRING_PTR(str);
+  mrb_int len = RSTRING_LEN(str);
+
+  /* `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;
+
+  return mrb_str_to_dbl(mrb, str, TRUE);
+}
+#endif
+
 static mrb_irep*
 read_irep_record_1(mrb_state *mrb, const uint8_t *bin, size_t *len, uint8_t flags)
 {
@@ -125,7 +143,7 @@ read_irep_record_1(mrb_state *mrb, const uint8_t *bin, size_t *len, uint8_t flag
 
 #ifndef MRB_WITHOUT_FLOAT
       case IREP_TT_FLOAT:
-        irep->pool[i] = mrb_float_pool(mrb, mrb_str_to_dbl(mrb, s, FALSE));
+        irep->pool[i] = mrb_float_pool(mrb, str_to_double(mrb, s));
         break;
 #endif