Replace use of Process.getpgid which does not behave as intended on all platforms

lib/puma/control_cli.rb

@@ -179,39 +179,39 @@ def send_signal
       end
 
       begin
-        Process.getpgid @pid
-      rescue SystemCallError
-        if @command == "restart"
-          start
-        else
-          raise "No pid '#{@pid}' found"
-        end
-      end
 
-      case @command
-      when "restart"
-        Process.kill "SIGUSR2", @pid
+        case @command
+        when "restart"
+          Process.kill "SIGUSR2", @pid
 
-      when "halt"
-        Process.kill "QUIT", @pid
+        when "halt"
+          Process.kill "QUIT", @pid
 
-      when "stop"
-        Process.kill "SIGTERM", @pid
+        when "stop"
+          Process.kill "SIGTERM", @pid
 
-      when "stats"
-        puts "Stats not available via pid only"
-        return
+        when "stats"
+          puts "Stats not available via pid only"
+          return
 
-      when "reload-worker-directory"
-        puts "reload-worker-directory not available via pid only"
-        return
+        when "reload-worker-directory"
+          puts "reload-worker-directory not available via pid only"
+          return
 
-      when "phased-restart"
-        Process.kill "SIGUSR1", @pid
+        when "phased-restart"
+          Process.kill "SIGUSR1", @pid
 
-      else
-        message "Puma is started"
-        return
+        else
+          message "Puma is started"
+          return
+        end
+
+      rescue SystemCallError
+        if @command == "restart"
+          start
+        else
+          raise "No pid '#{@pid}' found"
+        end
       end
 
       message "Command #{@command} sent success"

test/test_integration.rb

@@ -155,7 +155,7 @@ def test_phased_restart_via_pumactl
     @events.stdout.rewind
     log = @events.stdout.readlines.join("")
     assert_match(/TERM sent/, log)
-    assert_match(/Worker \d \(pid: \d+\) booted, phase: 1/, log)
+    assert_match(/- Worker \d \(pid: \d+\) booted, phase: 1/, log)
 
     # Stop
     ccli = Puma::ControlCLI.new %W!-S #{@state_path} stop!, sout
@@ -164,6 +164,29 @@ def test_phased_restart_via_pumactl
     assert_kind_of Thread, t.join(5), "server didn't stop"
   end
 
+  def test_kill_unknown_via_pumactl
+    if Puma.jruby? || Puma.windows?
+      assert true
+      return
+    end
+
+    # we run ls to get a 'safe' pid to pass off as puma in cli stop
+    # do not want to accidently kill a valid other process
+    io = IO.popen("ls")
+    safe_pid = io.pid
+    Process.wait safe_pid
+
+    sout = StringIO.new
+
+    e = assert_raises SystemExit do
+      ccli = Puma::ControlCLI.new %W!-p #{safe_pid} stop!, sout
+      ccli.run
+    end
+    sout.rewind
+    assert_match(/No pid '\d+' found/, sout.readlines.join(""))
+    assert_equal(1, e.status)
+  end
+
   def test_restart_closes_keepalive_sockets
     server("-q test/hello.ru")