Rerender and enter raw mode again by SIGCONT (#727)

lib/reline/io/ansi.rb

@@ -347,6 +347,13 @@ def clear_screen
 
   def set_winch_handler(&handler)
     @old_winch_handler = Signal.trap('WINCH', &handler)
+    @old_cont_handler = Signal.trap('CONT') do
+      @input.raw!(intr: true) if @input.tty?
+      # Rerender the screen. Note that screen size might be changed while suspended.
+      handler.call
+    end
+  rescue ArgumentError
+    # Signal.trap may raise an ArgumentError if the platform doesn't support the signal.
   end
 
   def prep
@@ -360,5 +367,6 @@ def deprep(otio)
     # Disable bracketed paste
     @output.write "\e[?2004l" if Reline.core.config.enable_bracketed_paste && both_tty?
     Signal.trap('WINCH', @old_winch_handler) if @old_winch_handler
+    Signal.trap('CONT', @old_cont_handler) if @old_cont_handler
   end
 end

test/reline/yamatanooroti/test_rendering.rb

@@ -1840,6 +1840,25 @@ def test_thread_safe
       EOC
     end
 
+    def test_stop_continue
+      pidfile = Tempfile.create('pidfile')
+      rubyfile = Tempfile.create('rubyfile')
+      rubyfile.write <<~RUBY
+        File.write(#{pidfile.path.inspect}, Process.pid)
+        p Reline.readmultiline('>'){false}
+      RUBY
+      rubyfile.close
+      start_terminal(40, 50, ['bash'])
+      write "ruby -I#{@pwd}/lib -rreline #{rubyfile.path}\n"
+      write "abc\ndef\nhi"
+      pid = pidfile.tap(&:rewind).read.to_i
+      Process.kill(:STOP, pid) unless pid.zero?
+      write "fg\n"
+      write "\ebg"
+      close
+      assert_include result.join("\n"), ">abc\n>def\n>ghi\n"
+    end
+
     def write_inputrc(content)
       File.open(@inputrc_file, 'w') do |f|
         f.write content