Check that the float is within the range of an int before casting.

Exiv2 · Aug 3, 2021 · 48da0e9 · 48da0e9
1 parent 388f254
commit 48da0e9
Showing 1 changed file with 14 additions and 12 deletions.
diff --git 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>
@@ -687,27 +688,28 @@ namespace Exiv2 {
 
     Rational floatToRationalCast(float f)
     {
-#if defined(_MSC_VER) && _MSC_VER < 1800
-        if (!_finite(f)) {
-#else
-        if (!std::isfinite(f)) {
-#endif
-            return Rational(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 flow.)
+        const double d = f;
+        const bool in_range = INT_MIN <= d && d <= INT_MAX;
+        if (!in_range) {
+            return Rational(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 int32_t nom = static_cast<int32_t>(f * den + rnd);
+        const float rnd = d >= 0 ? 0.5f : -0.5f;
+        const int32_t nom = static_cast<int32_t>(d * den + rnd);
         const int32_t g = gcd(nom, den);
 
         return Rational(nom / g, den / g);