From 5ef1e527a1d807d3023f0ac989b415fe6175af8b Mon Sep 17 00:00:00 2001
From: Andrew Kane <andrew@ankane.org>
Date: Tue, 22 Apr 2025 20:16:16 -0700
Subject: [PATCH 1/2] Fix Fiddle::Pointer#ref behavior for FFI backend

---
 lib/fiddle/ffi_backend.rb   | 24 +++++++++++++-----------
 test/fiddle/test_pointer.rb | 13 +++++++++++++
 2 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/lib/fiddle/ffi_backend.rb b/lib/fiddle/ffi_backend.rb
index fc1746fd..37f8b936 100644
--- a/lib/fiddle/ffi_backend.rb
+++ b/lib/fiddle/ffi_backend.rb
@@ -219,7 +219,6 @@ class DLError < Error; end
   class ClearedReferenceError < Error; end
 
   class Pointer
-    attr_reader :ffi_ptr
     extend FFI::DataConverter
     native_type FFI::Type::Builtin::POINTER
 
@@ -285,7 +284,7 @@ def []=(*args, value)
           value = value.to_str(args[1])
         end
 
-        @ffi_ptr.put_bytes(args[0], value, 0, args[1])
+        ffi_ptr.put_bytes(args[0], value, 0, args[1])
       elsif args.size == 1
         if value.is_a?(Fiddle::Pointer)
           value = value.to_str(args[0] + 1)
@@ -293,7 +292,7 @@ def []=(*args, value)
           value = value.chr
         end
 
-        @ffi_ptr.put_bytes(args[0], value, 0, 1)
+        ffi_ptr.put_bytes(args[0], value, 0, 1)
       end
     rescue FFI::NullPointerError
       raise DLError.new("NULL pointer access")
@@ -332,9 +331,14 @@ def initialize(addr, size = nil, free = nil)
       end
       @free = free
       @ffi_ptr = ptr
+      @addr_ptr = nil
       @freed = false
     end
 
+    def ffi_ptr
+      @addr_ptr ? @addr_ptr.get_pointer(0) : @ffi_ptr
+    end
+
     module LibC
       extend FFI::Library
       ffi_lib FFI::Library::LIBC
@@ -363,11 +367,11 @@ def self.malloc(size, free = nil)
     end
 
     def null?
-      @ffi_ptr.null?
+      ffi_ptr.null?
     end
 
     def to_ptr
-      @ffi_ptr
+      ffi_ptr
     end
 
     def size
@@ -386,9 +390,9 @@ def call_free
       return if @free.nil?
       return if @freed
       if @free == RUBY_FREE
-        LibC::FREE.call(@ffi_ptr)
+        LibC::FREE.call(ffi_ptr)
       else
-        @free.call(@ffi_ptr)
+        @free.call(ffi_ptr)
       end
       @freed = true
     end
@@ -492,10 +496,8 @@ def -@
     end
 
     def ref
-      cptr = Pointer.malloc(FFI::Type::POINTER.size, RUBY_FREE)
-      cptr.ffi_ptr.put_pointer(0, ffi_ptr)
-      cptr.size = 0
-      cptr
+      @addr_ptr ||= FFI::MemoryPointer.new(:pointer).put_pointer(0, @ffi_ptr)
+      Pointer.new(@addr_ptr, 0)
     end
   end
 
diff --git a/test/fiddle/test_pointer.rb b/test/fiddle/test_pointer.rb
index 6f086f00..da2cc20c 100644
--- a/test/fiddle/test_pointer.rb
+++ b/test/fiddle/test_pointer.rb
@@ -187,6 +187,19 @@ def test_cmp
       assert_nil(ptr <=> 10, '10 should not be comparable')
     end
 
+    def test_ref
+      ptr = Fiddle::Pointer["hello"]
+      ref = ptr.ref
+      assert_equal(0, ref.size)
+      assert_nil(ref.free)
+      assert_equal(ptr, ref.ptr)
+
+      ptr2 = Fiddle::Pointer["world"]
+      ptr.ref[0, Fiddle::SIZEOF_VOIDP] = ptr2.ref
+      assert_equal("world", ptr.to_s)
+      assert_equal(ptr.to_i, ptr2.to_i)
+    end
+
     def test_ref_ptr
       if ffi_backend?
         omit("Fiddle.dlwrap([]) isn't supported with FFI backend")

From 746747071b6154813518822c3106bf1ad43df8a7 Mon Sep 17 00:00:00 2001
From: Andrew Kane <andrew@ankane.org>
Date: Tue, 22 Apr 2025 22:09:54 -0700
Subject: [PATCH 2/2] Add note about pointer thread safety for FFI backend
 [skip ci]

---
 lib/fiddle/ffi_backend.rb | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/fiddle/ffi_backend.rb b/lib/fiddle/ffi_backend.rb
index 37f8b936..275d090c 100644
--- a/lib/fiddle/ffi_backend.rb
+++ b/lib/fiddle/ffi_backend.rb
@@ -218,6 +218,7 @@ class Error < StandardError; end
   class DLError < Error; end
   class ClearedReferenceError < Error; end
 
+  # Pointer isn't thread safe for now
   class Pointer
     extend FFI::DataConverter
     native_type FFI::Type::Builtin::POINTER