From d24badbfdaff9f0efca0a41db2ed1c7660c578cf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Wed, 22 Aug 2012 20:50:39 +0200
Subject: [PATCH] Fixed #4068 (Endless loop inside MathLib::add())

---
 lib/mathlib.cpp      | 12 ++++++++----
 test/testmathlib.cpp |  2 ++
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/lib/mathlib.cpp b/lib/mathlib.cpp
index a00cdc3b0..799e61ae8 100644
--- a/lib/mathlib.cpp
+++ b/lib/mathlib.cpp
@@ -201,9 +201,11 @@ std::string MathLib::add(const std::string & first, const std::string & second)
 
     double d1 = toDoubleNumber(first);
     double d2 = toDoubleNumber(second);
-    while (d1 > 100000.0 * d2 && toString<double>(d1+d2)==first)
+
+    int count = 0;
+    while (d1 > 100000.0 * d2 && toString<double>(d1+d2)==first && ++count<5)
         d2 *= 10.0;
-    while (d2 > 100000.0 * d1 && toString<double>(d1+d2)==second)
+    while (d2 > 100000.0 * d1 && toString<double>(d1+d2)==second && ++count<5)
         d1 *= 10.0;
 
     return toString<double>(d1 + d2);
@@ -217,9 +219,11 @@ std::string MathLib::subtract(const std::string &first, const std::string &secon
 
     double d1 = toDoubleNumber(first);
     double d2 = toDoubleNumber(second);
-    while (d1 > 100000.0 * d2 && toString<double>(d1-d2)==first)
+
+    int count = 0;
+    while (d1 > 100000.0 * d2 && toString<double>(d1-d2)==first && ++count<5)
         d2 *= 10.0;
-    while (d2 > 100000.0 * d1 && toString<double>(d1-d2)==second)
+    while (d2 > 100000.0 * d1 && toString<double>(d1-d2)==second && ++count<5)
         d1 *= 10.0;
 
     return toString<double>(d1 - d2);
diff --git a/test/testmathlib.cpp b/test/testmathlib.cpp
index b0ab04c57..62e43c94c 100644
--- a/test/testmathlib.cpp
+++ b/test/testmathlib.cpp
@@ -88,6 +88,7 @@ private:
         ASSERT_EQUALS("1"  , MathLib::add("1", "0"));
         ASSERT_EQUALS("0"  , MathLib::add("0", "0."));
         ASSERT_EQUALS("1.0000001"  , MathLib::add("1", "0.00000001"));  // #4016
+        ASSERT_EQUALS("30666.22"  , MathLib::add("30666.22", "0.0"));  // #4068
 
         // subtraction
         ASSERT_EQUALS("254", MathLib::subtract("0xff", "1"));
@@ -98,6 +99,7 @@ private:
         ASSERT_EQUALS("1"  , MathLib::subtract("1", "0"));
         ASSERT_EQUALS("0"  , MathLib::subtract("0", "0."));
         ASSERT_EQUALS("0.99999999"  , MathLib::subtract("1", "0.00000001")); // #4016
+        ASSERT_EQUALS("30666.22"  , MathLib::subtract("30666.22", "0.0"));  // #4068
 
         // multiply
         ASSERT_EQUALS("-0.003"          , MathLib::multiply("-1e-3", "3"));