fix: handle zero denominator

Returns Float::NAN when 0/0 and Float::INFINITY when N/0 close #12
tonytonyjan · Oct 2, 2017 · 0a0ca2e · 0a0ca2e
1 parent 2f245ac
commit 0a0ca2e
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Showing 4 changed files with 34 additions and 4 deletions.
diff --git a/ext/exif/data.c b/ext/exif/data.c
@@ -20,6 +20,8 @@ static VALUE brackets(VALUE self, VALUE ifd_symbol);
 static void each_content(ExifContent *ec, void *user_data);
 static void each_entry(ExifEntry *, void *user_data);
 static VALUE exif_entry_to_rb_value(ExifEntry *);
+static VALUE rational_to_num(ExifRational rational);
+static VALUE srational_to_num(ExifSRational srational);
 
 void init_data(){
   int length;
@@ -168,23 +170,23 @@ static VALUE exif_entry_to_rb_value(ExifEntry *entry){
       ret = rb_ary_new2(entry->components);
       for(i = 0; i < entry->components; i++){
         rational = exif_get_rational(entry->data + i * size, order);
-        rb_ary_push(ret, rb_rational_new(ULONG2NUM(rational.numerator), ULONG2NUM(rational.denominator)));
+        rb_ary_push(ret, rational_to_num(rational));
       }
     } else {
       rational = exif_get_rational(entry->data, order);
-      ret = rb_rational_new(ULONG2NUM(rational.numerator), ULONG2NUM(rational.denominator));
+      ret = rational_to_num(rational);
     }
     break;
   case EXIF_FORMAT_SRATIONAL:
     if(entry->components > 1){
       ret = rb_ary_new2(entry->components);
       for(int i = 0; i < entry->components; i++){
         srational = exif_get_srational(entry->data + i * size, order);
-        rb_ary_push(ret, rb_rational_new(LONG2FIX(srational.numerator), LONG2FIX(srational.denominator)));
+        rb_ary_push(ret, srational_to_num(srational));
       }
     } else {
       srational = exif_get_srational(entry->data, order);
-      ret = rb_rational_new(LONG2FIX(srational.numerator), LONG2FIX(srational.denominator));
+      ret = srational_to_num(srational);
     }
     break;
   case EXIF_FORMAT_DOUBLE:
@@ -195,3 +197,21 @@ static VALUE exif_entry_to_rb_value(ExifEntry *entry){
 
   return ret;
 }
+
+VALUE rational_to_num(ExifRational rational){
+  if(rational.numerator == 0 && rational.denominator == 0)
+    return DBL2NUM(NAN);
+  else if(rational.denominator == 0)
+    return DBL2NUM(INFINITY);
+  else
+    return rb_rational_new(ULONG2NUM(rational.numerator), ULONG2NUM(rational.denominator));
+}
+
+VALUE srational_to_num(ExifSRational srational){
+  if(srational.numerator == 0 && srational.denominator == 0)
+    return DBL2NUM(NAN);
+  else if(srational.denominator == 0)
+    return DBL2NUM(INFINITY);
+  else
+    return rb_rational_new(LONG2NUM(srational.numerator), LONG2NUM(srational.denominator));
+}
diff --git a/test/infinity.jpg b/test/infinity.jpg
diff --git a/test/nan.jpg b/test/nan.jpg
diff --git a/test/test_exif.rb b/test/test_exif.rb
@@ -221,4 +221,14 @@ def test_type_error
       Exif::Data.new(123)
     end
   end
+
+  def test_nan
+    data = Exif::Data.new(IO.read(File.expand_path('../nan.jpg', __FILE__)))
+    assert data.exposure_index.nan?
+  end
+
+  def test_infinity
+    data = Exif::Data.new(IO.read(File.expand_path('../infinity.jpg', __FILE__)))
+    assert_equal Float::INFINITY, data.exposure_index
+  end
 end