From 0f3930426515848be755c5480df354fa9e2109f4 Mon Sep 17 00:00:00 2001
From: cremno <cremno@mail.ru>
Date: Mon, 5 May 2014 15:24:22 +0200
Subject: add function for checked mrb_int addition

---
 src/numeric.c |  4 +---
 src/vm.c      | 13 ++++---------
 2 files changed, 5 insertions(+), 12 deletions(-)

(limited to 'src')

diff --git a/src/numeric.c b/src/numeric.c
index 56835edbf..8ea71ada6 100644
--- a/src/numeric.c
+++ b/src/numeric.c
@@ -1109,9 +1109,7 @@ mrb_fixnum_plus(mrb_state *mrb, mrb_value x, mrb_value y)
 
     if (a == 0) return y;
     b = mrb_fixnum(y);
-    c = a + b;
-    if (((a < 0) ^ (b < 0)) == 0 && (a < 0) != (c < 0)) {
-      /* integer overflow */
+    if (mrb_int_add_overflow(a, b, &c)) {
       return mrb_float_value(mrb, (mrb_float)a + (mrb_float)b);
     }
     return mrb_fixnum_value(c);
diff --git a/src/vm.c b/src/vm.c
index 0e3c0a81e..85a121f2c 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -12,6 +12,7 @@
 #include "mruby/class.h"
 #include "mruby/hash.h"
 #include "mruby/irep.h"
+#include "mruby/numeric.h"
 #include "mruby/proc.h"
 #include "mruby/range.h"
 #include "mruby/string.h"
@@ -1610,12 +1611,7 @@ RETRY_TRY_BLOCK:
 
           x = mrb_fixnum(regs_a[0]);
           y = mrb_fixnum(regs_a[1]);
-          z = x + y;
-#ifdef MRB_WORD_BOXING
-          z = (z << MRB_FIXNUM_SHIFT) / (1 << MRB_FIXNUM_SHIFT);
-#endif
-          if ((x < 0) != (z < 0) && ((x < 0) ^ (y < 0)) == 0) {
-            /* integer overflow */
+          if (mrb_int_add_overflow(x, y, &z)) {
             SET_FLT_VALUE(mrb, regs_a[0], (mrb_float)x + (mrb_float)y);
             break;
           }
@@ -1842,10 +1838,9 @@ RETRY_TRY_BLOCK:
         {
           mrb_int x = regs[a].attr_i;
           mrb_int y = GETARG_C(i);
-          mrb_int z = x + y;
+          mrb_int z;
 
-          if (((x < 0) ^ (y < 0)) == 0 && (x < 0) != (z < 0)) {
-            /* integer overflow */
+          if (mrb_int_add_overflow(x, y, &z)) {
             SET_FLT_VALUE(mrb, regs[a], (mrb_float)x + (mrb_float)y);
             break;
           }
-- 
cgit v1.2.3


From cf8df563c0ea9b98714e701ad235acbefc091558 Mon Sep 17 00:00:00 2001
From: cremno <cremno@mail.ru>
Date: Mon, 5 May 2014 15:28:26 +0200
Subject: add function for checked mrb_int subtraction

---
 include/mruby/numeric.h | 10 ++++++++++
 src/numeric.c           |  4 +---
 src/vm.c                | 12 +++---------
 3 files changed, 14 insertions(+), 12 deletions(-)

(limited to 'src')

diff --git a/include/mruby/numeric.h b/include/mruby/numeric.h
index 35be32a01..fe4f3b264 100644
--- a/include/mruby/numeric.h
+++ b/include/mruby/numeric.h
@@ -45,6 +45,16 @@ mrb_int_add_overflow(mrb_int augend, mrb_int addend, mrb_int *sum)
   return !!(((x ^ z) & (y ^ z)) & MRB_INT_OVERFLOW_MASK);
 }
 
+static inline mrb_bool
+mrb_int_sub_overflow(mrb_int minuend, mrb_int subtrahend, mrb_int *difference)
+{
+  mrb_uint x = (mrb_uint)minuend;
+  mrb_uint y = (mrb_uint)subtrahend;
+  mrb_uint z = (mrb_uint)(x - y);
+  *difference = (mrb_int)z;
+  return !!(((x ^ z) & (~y ^ z)) & MRB_INT_OVERFLOW_MASK);
+}
+
 #undef MRB_INT_OVERFLOW_MASK
 #undef mrb_uint
 #undef MRB_UINT_MAKE
diff --git a/src/numeric.c b/src/numeric.c
index 8ea71ada6..7b025c34d 100644
--- a/src/numeric.c
+++ b/src/numeric.c
@@ -1145,9 +1145,7 @@ mrb_fixnum_minus(mrb_state *mrb, mrb_value x, mrb_value y)
     mrb_int b, c;
 
     b = mrb_fixnum(y);
-    c = a - b;
-    if (((a < 0) ^ (b < 0)) != 0 && (a < 0) != (c < 0)) {
-      /* integer overflow */
+    if (mrb_int_sub_overflow(a, b, &c)) {
       return mrb_float_value(mrb, (mrb_float)a - (mrb_float)b);
     }
     return mrb_fixnum_value(c);
diff --git a/src/vm.c b/src/vm.c
index 85a121f2c..ae19db0b6 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -1669,12 +1669,7 @@ RETRY_TRY_BLOCK:
 
           x = mrb_fixnum(regs[a]);
           y = mrb_fixnum(regs[a+1]);
-          z = x - y;
-#ifdef MRB_WORD_BOXING
-          z = (z << MRB_FIXNUM_SHIFT) / (1 << MRB_FIXNUM_SHIFT);
-#endif
-          if (((x < 0) ^ (y < 0)) != 0 && (x < 0) != (z < 0)) {
-            /* integer overflow */
+          if (mrb_int_sub_overflow(x, y, &z)) {
             SET_FLT_VALUE(mrb, regs[a], (mrb_float)x - (mrb_float)y);
             break;
           }
@@ -1876,10 +1871,9 @@ RETRY_TRY_BLOCK:
         {
           mrb_int x = regs_a[0].attr_i;
           mrb_int y = GETARG_C(i);
-          mrb_int z = x - y;
+          mrb_int z;
 
-          if ((x < 0) != (z < 0) && ((x < 0) ^ (y < 0)) != 0) {
-            /* integer overflow */
+          if (mrb_int_sub_overflow(x, y, &z)) {
             SET_FLT_VALUE(mrb, regs_a[0], (mrb_float)x - (mrb_float)y);
           }
           else {
-- 
cgit v1.2.3