From 7c2ab1d7dea740fa30689d1fc2cecda85c07586f Mon Sep 17 00:00:00 2001
From: Kevin Backhouse <kevinbackhouse@github.com>
Date: Wed, 4 Aug 2021 13:34:21 +0100
Subject: [PATCH] Check that the float is within the range of an int before
 casting.

---
 src/types.cpp | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/src/types.cpp b/src/types.cpp
index 9a51d89b..a24ca8a3 100644
--- a/src/types.cpp
+++ b/src/types.cpp
@@ -36,6 +36,7 @@
 #include <sstream>
 #include <utility>
 #include <cctype>
+#include <climits>
 #include <ctime>
 #include <cstdio>
 #include <cstdlib>
@@ -670,27 +671,28 @@ namespace Exiv2 {
 
     Rational floatToRationalCast(float f)
     {
-#if defined(_MSC_VER) && _MSC_VER < 1800
-        if (!_finite(f)) {
-#else
-        if (!std::isfinite(f)) {
-#endif
-            return {f > 0 ? 1 : -1, 0};
+
+        // Convert f to double because it simplifies the "in_range" check
+        // below. (INT_MAX can be represented accurately as a double, but
+        // gets rounded when it's converted to float.)
+        const double d = f;
+        const bool in_range = INT_MIN <= d && d <= INT_MAX;
+        if (!in_range) {
+            return {d > 0 ? 1 : -1, 0};
         }
         // Beware: primitive conversion algorithm
         int32_t den = 1000000;
-        const long f_as_long = static_cast<long>(f);
-        if (Safe::abs(f_as_long) > 2147) {
+        const long d_as_long = static_cast<long>(d);
+        if (Safe::abs(d_as_long) > 2147) {
             den = 10000;
         }
-        if (Safe::abs(f_as_long) > 214748) {
+        if (Safe::abs(d_as_long) > 214748) {
             den = 100;
         }
-        if (Safe::abs(f_as_long) > 21474836) {
+        if (Safe::abs(d_as_long) > 21474836) {
             den = 1;
         }
-        const float rnd = f >= 0 ? 0.5F : -0.5F;
-        const auto nom = static_cast<int32_t>(f * den + rnd);
+        const auto nom = static_cast<int32_t>(std::round(d * den));
         const int32_t g = gcd(nom, den);
 
         return {nom / g, den / g};