GH-45187: [Ruby] Ensure initializing all rb_memory_view_t members (#50234)

### Rationale for this change

`rb_memory_view_get()` callers may pass a non-zero-initialized `rb_memory_view_t`. `primitive_array_get()` and `buffer_get()` did not initialize `item_desc.components` and `item_desc.length`, which could cause `rb_memory_view_release()` to attempt to free an invalid pointer and abort the process.

### What changes are included in this PR?

This change initializes `item_desc.components` and `item_desc.length` in both `primitive_array_get()` and `buffer_get()`.

It also adds regression tests that verify releasing a memory view with a non-zero-initialized `rb_memory_view_t` does not crash for both `Arrow::Int32Array` and `Arrow::Buffer`.

### Are these changes tested?

Yes. Added regression tests in `test-memory-view.rb` that reproduced the crash before this change and pass after the fix.

### Are there any user-facing changes?

No.

**This PR contains a "Critical Fix".**

This change fixes a crash that could occur when `rb_memory_view_release()` is called with a memory view whose `item_desc` members were not initialized.
* GitHub Issue: #45187

Lead-authored-by: Aaditya Srinivasan <aadityasri03@gmail.com>
Co-authored-by: Sutou Kouhei <kou@cozmixng.org>
Signed-off-by: Sutou Kouhei <kou@clear-code.com>

Author: Reranko05

ruby/red-arrow/ext/arrow/memory-view.cpp

@@ -31,6 +31,7 @@
 #  undef private
 #endif
 
+#include <cstring>
 #include <sstream>
 
 namespace red_arrow {
@@ -220,6 +221,7 @@ namespace red_arrow {
         return false;
       }
       auto view_ = reinterpret_cast<memory_view *>(view);
+      memset(view_, 0, sizeof(memory_view));
       view_->obj = obj;
       view_->private_data = new PrivateData();
       auto array = GARROW_ARRAY(RVAL2GOBJ(obj));
@@ -231,9 +233,6 @@ namespace red_arrow {
       }
       view_->readonly = true;
       view_->ndim = 1;
-      view_->shape = NULL;
-      view_->strides = NULL;
-      view_->sub_offsets = NULL;
       return true;
     }
 
@@ -258,6 +257,7 @@ namespace red_arrow {
         return false;
       }
       auto view_ = reinterpret_cast<memory_view *>(view);
+      memset(view_, 0, sizeof(memory_view));
       view_->obj = obj;
       auto buffer = GARROW_BUFFER(RVAL2GOBJ(obj));
       auto arrow_buffer = garrow_buffer_get_raw(buffer);
@@ -275,9 +275,6 @@ namespace red_arrow {
       view_->byte_size = arrow_buffer->size();
       view_->readonly = true;
       view_->ndim = 1;
-      view_->shape = NULL;
-      view_->strides = NULL;
-      view_->sub_offsets = NULL;
       return true;
     }
 

ruby/red-arrow/test/test-memory-view.rb

@@ -431,4 +431,57 @@ def little_endian?
                    ])
     end
   end
+
+  sub_test_case("uninitialized rb_memory_view_t") do
+    def setup
+      libruby = Fiddle.dlopen(nil)
+
+      @rb_memory_view_get = Fiddle::Function.new(
+        libruby["rb_memory_view_get"],
+        [
+          Fiddle::TYPE_UINTPTR_T,
+          Fiddle::TYPE_VOIDP,
+          Fiddle::TYPE_INT,
+        ],
+        Fiddle::TYPE_BOOL
+      )
+
+      @rb_memory_view_release = Fiddle::Function.new(
+        libruby["rb_memory_view_release"],
+        [
+          Fiddle::TYPE_VOIDP,
+        ],
+        Fiddle::TYPE_BOOL
+      )
+    end
+
+    def assert_release(target)
+      # We should use sizeof(rb_memory_view_t) but it isn't available from Ruby.
+      # 256 must be larger than sizeof(rb_memory_view_t).
+      size = 256
+      Fiddle::Pointer.malloc(size, Fiddle::RUBY_FREE) do |view|
+        size.times do |i|
+          view[i] = 0xAA
+        end
+
+        assert do
+          @rb_memory_view_get.call(Fiddle.dlwrap(target), view, 0)
+        end
+
+        assert do
+          @rb_memory_view_release.call(view)
+        end
+      end
+    end
+
+    test("Int32Array") do
+      array = Arrow::Int32Array.new([1, 2, 3, 4, 5])
+      assert_release(array)
+    end
+
+    test("Buffer") do
+      buffer = Arrow::Buffer.new("hello")
+      assert_release(buffer)
+    end
+  end
 end