Add validation for integer values in attribute writing

Author: kojix2

lib/hdf5/attribute.rb

@@ -116,6 +116,7 @@ def normalize_data(value)
 
     def datatype_id_for(values)
       if values.all? { |item| item.is_a?(Integer) }
+        validate_native_int_range!(values)
         HDF5::FFI.H5T_NATIVE_INT
       elsif values.all? { |item| item.is_a?(Numeric) }
         HDF5::FFI.H5T_NATIVE_DOUBLE
@@ -135,5 +136,21 @@ def buffer_for(values)
 
       buffer
     end
+
+    def native_int_bounds
+      bits = ::FFI.type_size(:int) * 8
+      max = (1 << (bits - 1)) - 1
+      min = -(1 << (bits - 1))
+      [min, max]
+    end
+
+    def validate_native_int_range!(values)
+      min, max = native_int_bounds
+      out_of_range = values.find { |value| value < min || value > max }
+      return unless out_of_range
+
+      raise HDF5::Error,
+            "Integer value #{out_of_range} is outside native int range (#{min}..#{max}). Use a smaller value."
+    end
   end
 end

test/hdf5_test.rb

@@ -154,6 +154,23 @@ class HDF5Test < Test::Unit::TestCase
     end
   end
 
+  test 'rejects integer values outside native int range on attribute write' do
+    min = -(1 << (::FFI.type_size(:int) * 8 - 1))
+    max = (1 << (::FFI.type_size(:int) * 8 - 1)) - 1
+
+    Dir.mktmpdir do |dir|
+      path = File.join(dir, 'attribute-overflow.h5')
+
+      HDF5::File.create(path) do |file|
+        dataset = file.create_dataset('values', [1, 2, 3])
+        error = assert_raise(HDF5::Error) do
+          dataset.attrs['scale'] = [max + 1]
+        end
+        assert_include(error.message, "#{min}..#{max}")
+      end
+    end
+  end
+
   test 'group list_datasets returns only datasets' do
     Dir.mktmpdir do |dir|
       path = File.join(dir, 'group-list.h5')