Import JRuby implementation

Fig GH-104

lib/fiddle/jruby.rb is based on
https://github.com/jruby/jruby/blob/master/lib/ruby/stdlib/fiddle/jruby.rb
.

Here are changes for it:

* Move `Fiddle::TYPE_*` to `Fiddle::Types::*`
* Add `Fiddle::Types::VARIADIC`
* Add `Fiddle::Types::CONST_STRING`
* Add `Fiddle::Types::BOOL`
* Add `Fiddle::Types::INT8_T`
* Add `Fiddle::Types::UINT8_T`
* Add `Fiddle::Types::INT16_T`
* Add `Fiddle::Types::UINT16_T`
* Add `Fiddle::Types::INT32_T`
* Add `Fiddle::Types::UINT32_T`
* Add `Fiddle::Types::INT64_T`
* Add `Fiddle::Types::UINT64_T`
* Add more `Fiddle::ALIGN_*` for the above new `Fiddle::Types::*`
* Add more `Fiddle::SIZEOF_*` for the above new `Fiddle::Types::*`
* Add support for specifying type as not only `Fiddle::Types::*` but also
  `Symbol` like `:int`
* Add support for variable size arguments in `Fiddle::Function`
* Add `Fiddle::Closure#free`
* Add `Fiddle::Closure#freed?`
* Add `Fiddle::Error` as base the error class
* Add `Fiddle::Pointer#call_free` and stop using `FFI::AutoPointer` in
  `Fiddle::Pointer`
* Add support for `Fiddle::Pointer.malloc {}`
  `Fiddle::Pointer`
* Add support for `Fiddle::Pointer#free=`
* Add `Fiddle::Pointer#freed?`
* Use binary string not C string for `Fiddle::Pointer#[]`
* Add `Fiddle::Handle.sym_defined?`
* Add `Fiddle::Handle#sym_defined?`
* Add `Fiddle::Handle::DEFAULT`
* Add `Fiddle::ClearedReferenceError`
* Add no-op `Fiddle::Pinned`

Some features are still "not implemented". So there are some "omit"s
for JRuby in tests.

.github/workflows/ci.yml

@@ -25,6 +25,7 @@ jobs:
           - '3.1'
           - '3.2'
           - debug
+          - jruby
         include:
           - { os: windows-latest , ruby: mingw }
           - { os: windows-latest , ruby: mswin }
@@ -53,13 +54,9 @@ jobs:
           matrix.ruby == 'mingw' ||
           matrix.ruby == 'mswin'
 
-      - run: rake build
-
-      - run: gem install pkg/*.gem
-
       - run: rake test
-        env:
-          RUBYOPT: --disable=gems
+
+      - run: rake install
 
       - name: Run test against installed gem
         # We can't use Fiddle gem with RubyInstaller because
@@ -69,6 +66,7 @@ jobs:
           matrix.os != 'windows-latest' ||
           (matrix.os == 'windows-latest' && matrix.ruby == 'mswin')
         run: |
+          ruby -run -e mkdir -- -p tmp/
           ruby -run -e cp -- -pr test/ tmp/
           cd tmp
           ruby test/run.rb

Rakefile

@@ -17,8 +17,13 @@ namespace :version do
   end
 end
 
-require 'rake/extensiontask'
-Rake::ExtensionTask.new("fiddle")
-Rake::ExtensionTask.new("-test-/memory_view")
+if RUBY_ENGINE == "ruby"
+  require 'rake/extensiontask'
+  Rake::ExtensionTask.new("fiddle")
+  Rake::ExtensionTask.new("-test-/memory_view")
+  task test: :compile
+else
+  task :compile
+end
 
-task :default => [:compile, :test]
+task default: :test

ext/fiddle/extconf.rb

@@ -1,6 +1,11 @@
 # frozen_string_literal: true
 require 'mkmf'
 
+if RUBY_ENGINE == "jruby"
+  File.write('Makefile', dummy_makefile("").join)
+  return
+end
+
 # :stopdoc:
 
 def gcc?

fiddle.gemspec

@@ -40,6 +40,7 @@ Gem::Specification.new do |spec|
     "lib/fiddle/cparser.rb",
     "lib/fiddle/function.rb",
     "lib/fiddle/import.rb",
+    "lib/fiddle/jruby.rb",
     "lib/fiddle/pack.rb",
     "lib/fiddle/struct.rb",
     "lib/fiddle/types.rb",

lib/fiddle.rb

@@ -1,6 +1,11 @@
 # frozen_string_literal: true
 
-require 'fiddle.so'
+case RUBY_ENGINE
+when 'jruby'
+  require 'fiddle/jruby'
+else
+  require 'fiddle.so'
+end
 require 'fiddle/closure'
 require 'fiddle/function'
 require 'fiddle/version'
@@ -10,36 +15,63 @@ module Fiddle
     # Returns the last win32 +Error+ of the current executing +Thread+ or nil
     # if none
     def self.win32_last_error
-      Thread.current[:__FIDDLE_WIN32_LAST_ERROR__]
+      if RUBY_ENGINE == 'jruby'
+        errno = FFI.errno
+        errno == 0 ? nil : errno
+      else
+        Thread.current[:__FIDDLE_WIN32_LAST_ERROR__]
+      end
     end
 
     # Sets the last win32 +Error+ of the current executing +Thread+ to +error+
     def self.win32_last_error= error
-      Thread.current[:__FIDDLE_WIN32_LAST_ERROR__] = error
+      if RUBY_ENGINE == 'jruby'
+        FFI.errno = error || 0
+      else
+        Thread.current[:__FIDDLE_WIN32_LAST_ERROR__] = error
+      end
     end
 
     # Returns the last win32 socket +Error+ of the current executing
     # +Thread+ or nil if none
     def self.win32_last_socket_error
-      Thread.current[:__FIDDLE_WIN32_LAST_SOCKET_ERROR__]
+      if RUBY_ENGINE == 'jruby'
+        errno = FFI.errno
+        errno == 0 ? nil : errno
+      else
+        Thread.current[:__FIDDLE_WIN32_LAST_SOCKET_ERROR__]
+      end
     end
 
     # Sets the last win32 socket +Error+ of the current executing
     # +Thread+ to +error+
     def self.win32_last_socket_error= error
-      Thread.current[:__FIDDLE_WIN32_LAST_SOCKET_ERROR__] = error
+      if RUBY_ENGINE == 'jruby'
+        FFI.errno = error || 0
+      else
+        Thread.current[:__FIDDLE_WIN32_LAST_SOCKET_ERROR__] = error
+      end
     end
   end
 
   # Returns the last +Error+ of the current executing +Thread+ or nil if none
   def self.last_error
-    Thread.current[:__FIDDLE_LAST_ERROR__]
+    if RUBY_ENGINE == 'jruby'
+      errno = FFI.errno
+      errno == 0 ? nil : errno
+    else
+      Thread.current[:__FIDDLE_LAST_ERROR__]
+    end
   end
 
   # Sets the last +Error+ of the current executing +Thread+ to +error+
   def self.last_error= error
-    Thread.current[:__DL2_LAST_ERROR__] = error
-    Thread.current[:__FIDDLE_LAST_ERROR__] = error
+    if RUBY_ENGINE == 'jruby'
+      FFI.errno = error || 0
+    else
+      Thread.current[:__DL2_LAST_ERROR__] = error
+      Thread.current[:__FIDDLE_LAST_ERROR__] = error
+    end
   end
 
   # call-seq: dlopen(library) => Fiddle::Handle