From 2741f970507e6171567a4b6cb9739d41fa7dd881 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrick=20L=C3=BChne?= <patrick@luehne.de>
Date: Tue, 26 May 2020 00:15:22 +0200
Subject: [PATCH] Attach to existing pseudoterminal

---
 github-fast-env.rb  | 41 ++++++++--------------
 github-fast-envd.rb | 84 +++++++++++++++++++++------------------------
 2 files changed, 54 insertions(+), 71 deletions(-)

diff --git a/github-fast-env.rb b/github-fast-env.rb
index d287834..0b0b46e 100755
--- a/github-fast-env.rb
+++ b/github-fast-env.rb
@@ -48,15 +48,15 @@ def log(level, message)
 	end
 end
 
-def read_command(control_socket)
-	ready_ios = IO.select([control_socket], [], [], 10)
+def read_command
+	ready_ios = IO.select([$control_socket], [], [], 10)
 
 	if not ready_ios
 		log "error", "timeout while communicating with github-fast-envd"
 		exit 1
 	end
 
-	response = control_socket.readline.strip.split(" ", 2)
+	response = $control_socket.readline.strip.split(" ", 2)
 
 	if response.empty?
 		log "error", "malformed response from github-fast-envd"
@@ -98,8 +98,13 @@ log "info", "connected to control socket"
 
 encoded_script_path = Base64.encode64(script_path).delete("\n")
 
+read_ios = [$control_socket]
+
 if $options[:interactive]
-	$control_socket.puts "new v1 pseudoterminal #{encoded_script_path}"
+	pseudoterminal_path = File.readlink("/proc/self/fd/0")
+	encoded_pseudoterminal_path = Base64.encode64(pseudoterminal_path).delete("\n")
+
+	$control_socket.puts "new v1 pseudoterminal #{encoded_pseudoterminal_path} #{encoded_script_path}"
 else
 	$control_socket.puts "new v1 named-pipes #{encoded_script_path}"
 end
@@ -107,7 +112,7 @@ end
 pipes = {"stdin" => nil, "stdout" => nil, "stderr" => nil}
 
 while true
-	command, arguments = read_command($control_socket)
+	command, arguments = read_command
 
 	if command == "ready"
 		break
@@ -128,36 +133,18 @@ while true
 		pipes["stderr"] = File::open("#{pipe_base_path}.stderr", "r")
 		pipes["stderr"].sync = true
 
-		read_ios = [$control_socket, $stdin, pipes["stdout"], pipes["stderr"]]
+		read_ios += [$stdin, pipes["stdout"], pipes["stderr"]]
 
 		log "info", "connected via named pipes"
-	elsif command == "pseudoterminal"
-		if arguments.empty?
-			log "error", "malformed response"
-			exit 1
-		end
 
-		pseudoterminal_path = Base64.decode64(arguments[0])
-
-		log "info", "connecting to pseudoterminal at #{pseudoterminal_path}"
-
-		pseudoterminal_io = File::open(pseudoterminal_path, File::RDWR | File::NOCTTY)
-
-		pipes["stdin"] = pseudoterminal_io
-		pipes["stdout"] = pseudoterminal_io
-
-		read_ios = [$control_socket, $stdin, pipes["stdout"]]
-
-		log "info", "connected via pseudoterminal"
+		log "info", "ready"
+		$control_socket.puts "ready"
 	else
 		log "error", "malformed response"
 		exit 1
 	end
 end
 
-log "info", "ready"
-$control_socket.puts "ready"
-
 exit_code = "unknown"
 
 while read_ios.include?($control_socket) or read_ios.include?(pipes["stdout"]) or read_ios.include?(pipes["stderr"])
@@ -180,7 +167,7 @@ while read_ios.include?($control_socket) or read_ios.include?(pipes["stdout"]) o
 				$stderr.write ready_read_io.readpartial(4096)
 			elsif ready_read_io.equal? $control_socket
 				log "trace", "reading from control socket"
-				command, arguments = read_command($control_socket)
+				command, arguments = read_command
 
 				if command != "done"
 					log "error", "malformed response from github-fast-envd"
diff --git a/github-fast-envd.rb b/github-fast-envd.rb
index d177ffc..aad0286 100755
--- a/github-fast-envd.rb
+++ b/github-fast-envd.rb
@@ -23,6 +23,10 @@ class ClientScriptError < StandardError
 	end
 end
 
+$original_stdin = $stdin.dup
+$original_stdout = $stdout.dup
+$original_stderr = $stderr.dup
+
 control_socket_path = "/tmp/github-fast-envd.sock"
 
 if File.exist?(control_socket_path) and File.socket?(control_socket_path)
@@ -36,7 +40,7 @@ File.chmod 0700, control_socket_path
 #	control_server.close
 #end
 
-$stderr.puts "serving control socket"
+$original_stderr.puts "serving control socket"
 
 connection_id = 0
 
@@ -101,7 +105,7 @@ def set_up_named_pipes(control_socket, connection_id)
 	stderr = File::open(stderr, "w")
 	stderr.sync = true
 
-	$stderr.puts "  set up named pipes"
+	$original_stderr.puts "  set up named pipes"
 
 	control_socket.puts "ready"
 
@@ -117,38 +121,23 @@ def set_up_named_pipes(control_socket, connection_id)
 	$stderr.reopen(stderr)
 end
 
-def set_up_pseudoterminal(control_socket)
-	require "pty"
+def set_up_pseudoterminal(control_socket, pseudoterminal_path)
+	pseudoterminal_io = File::open(pseudoterminal_path, File::RDWR | File::NOCTTY)
 
-	master, client = PTY.open
-	master.raw!
+	$original_stderr.puts "  connecting to pseudoterminal #{pseudoterminal_path}"
 
-	File.chmod 0600, client.path
+	$stdin.reopen(pseudoterminal_io)
+	$stdout.reopen(pseudoterminal_io)
+	$stderr.reopen(pseudoterminal_io)
 
-	client_path = Base64.encode64(client.path).delete("\n")
-	client.close
-
-	control_socket.puts "pseudoterminal #{client_path}"
-
-	$stderr.puts "  set up pseudoterminal"
+	$original_stderr.puts "  connected to pseudoterminal #{pseudoterminal_path}"
 
 	control_socket.puts "ready"
-
-	response = control_socket.readline.strip
-
-	if response != "ready"
-		raise ClientError.new "invalid command"
-		Kernel.exit!
-	end
-
-	$stdin.reopen(master)
-	$stdout.reopen(master)
-	$stderr.reopen(master)
 end
 
 while true
 	control_socket = control_server.accept
-	$stderr.puts "- new connection"
+	$original_stderr.puts "- new connection"
 
 	begin
 		command, arguments = read_command(control_socket)
@@ -157,7 +146,7 @@ while true
 			raise ClientError.new "unexpected command"
 		end
 
-		if arguments.length != 3
+		if arguments.empty?
 			raise ClientError.new "malformed command"
 		end
 
@@ -169,59 +158,65 @@ while true
 
 		mode = arguments[1]
 
-		if not ["named-pipes", "pseudoterminal"].include?(mode)
+		if mode == "named-pipes"
+			if arguments.length < 3
+				raise ClientError.new "malformed command"
+			end
+		elsif mode == "pseudoterminal"
+			if arguments.length < 4
+				raise ClientError.new "malformed command"
+			end
+
+			pseudoterminal_path = Base64.decode64(arguments[2])
+		else
 			raise ClientError.new "unknown mode (#{mode})"
 		end
 
-		script_path = Base64.decode64(arguments[2])
+		script_path = Base64.decode64(arguments.last)
 
 		connection_id += 1
 
 		child_process = fork {
-			original_stdin = $stdin.dup
-			original_stdout = $stdout.dup
-			original_stderr = $stderr.dup
-
 			exit_code = "unknown"
 
 			if mode == "named-pipes"
 				set_up_named_pipes(control_socket, connection_id)
 			else
-				set_up_pseudoterminal(control_socket)
+				set_up_pseudoterminal(control_socket, pseudoterminal_path)
 			end
 
-			original_stderr.puts "  executing script " + script_path
+			$original_stderr.puts "  executing script " + script_path
 
 			begin
 				begin
 					load script_path, true
 				rescue SystemExit => error
-					original_stderr.puts "  exit code: #{error.status}"
+					$original_stderr.puts "  exit code: #{error.status}"
 					exit_code = error.status
 				rescue StandardError => error
-					$stdin = original_stdin
-					$stdout = original_stdout
-					$stderr = original_stderr
+					$stdin = $original_stdin
+					$stdout = $original_stdout
+					$stderr = $original_stderr
 
 					raise ClientScriptError.new error
 				end
 			rescue ClientScriptError => error
 				# TODO: Restore pipes to make sure that syntax errors are caught
 				encoded_error_output = Base64.encode64(error.source.full_message).delete("\n")
-				original_stderr.puts "  error executing script, ignoring request"
+				$original_stderr.puts "  error executing script, ignoring request"
 				# TODO: if the begin/rescue blog has syntax errors, these go unnoticed
 				begin
 					control_socket.puts "script_error #{encoded_error_output}"
 				rescue
 				end
 			rescue ClientError => error
-				original_stderr.puts "  error communicating with client, ignoring request (#{error})"
+				$original_stderr.puts "  error communicating with client, ignoring request (#{error})"
 				begin
 					control_socket.puts "error #{error}"
 				rescue
 				end
 			rescue StandardError => error
-				original_stderr.puts "  error, ignoring request (#{error})"
+				$original_stderr.puts "  error, ignoring request (#{error})"
 				begin
 					control_socket.puts "error internal server error"
 				rescue
@@ -229,25 +224,26 @@ while true
 			end
 
 			begin
+				# TODO: which exit code to return when interrupted?
 				control_socket.puts "done #{exit_code}"
 			rescue
 			end
 			control_socket.close
 
-			original_stderr.puts "  finished handling request"
+			$original_stderr.puts "  finished handling request"
 
 			Kernel.exit!
 		}
 
 		Process.detach(child_process)
 	rescue ClientError => error
-		$stderr.puts "  error communicating with client, ignoring request (#{error})"
+		$original_stderr.puts "  error communicating with client, ignoring request (#{error})"
 		begin
 			control_socket.puts "error #{error}"
 		rescue
 		end
 	rescue StandardError => error
-		$stderr.puts "  error, ignoring request (#{error})"
+		$original_stderr.puts "  error, ignoring request (#{error})"
 		begin
 			control_socket.puts "error internal server error"
 		rescue