screen.go

/*
 * screend
 * Copyright (C) 2019 OkaeriPoland
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
package main

import (
	"github.com/pkg/errors"
	"strconv"
	"strings"
	"time"
)

type Screen struct {
	id   int
	name string
}

func runScreen(userName string, screenName string, runDirectory string, command string, logging bool) (Screen, error) {

	exists, err := doesScreenExists(userName, screenName)
	if err != nil {
		return Screen{}, err
	}

	if exists {
		return Screen{}, errors.New("SCREEN_ALREADY_EXISTS")
	}

	args := []string{"screen"}
	if logging {
		args = append(args, "-L")
	}
	args = append(args, "-S", screenName, "-dm")
	args = append(args, strings.Split(command, " ")...)

	userInfo, err := getUserInfoByName(userName)
	if err != nil {
		return Screen{}, err
	}

	_, err = executeCommand(userInfo, false, runDirectory, args...)
	if err != nil {
		if err.Error() == "exit status 1" {
			return Screen{}, errors.New("exit status 1: check command")
		}
		return Screen{}, err
	}

	time.Sleep(time.Second)
	screen, err := getScreenByName(userName, screenName)
	if err != nil {
		if err.Error() == "SCREEN_NOT_FOUND" {
			return Screen{}, errors.New("Screen " + screenName + " not present after creation")
		}
		return Screen{}, err
	}

	return screen, nil
}

func getRunningScreens(userName string) ([]Screen, error) {

	userInfo, err := getUserInfoByName(userName)
	if err != nil {
		return []Screen{}, err
	}

	output, _ := executeCommand(userInfo, true, "", "screen", "-ls")
	var screens []Screen
	lines := strings.Split(output, "\n")

	for _, line := range lines {

		if !strings.HasPrefix(line, "\t") {
			continue
		}

		lineParts := strings.Split(line, "\t")
		fullScreenName := lineParts[1]
		fullNameParts := strings.Split(fullScreenName, ".")

		name := strings.Join(fullNameParts[1:], ".")
		id, err := strconv.Atoi(fullNameParts[0])
		if err != nil {
			return []Screen{}, err
		}

		screens = append(screens, Screen{id, name})
	}

	return screens, nil
}

func doesScreenExists(userName string, screenName string) (bool, error) {

	_, err := getScreenByName(userName, screenName)
	if err != nil {
		if err.Error() == "SCREEN_NOT_FOUND" {
			return false, nil
		}
		return false, err
	}

	return true, nil
}

func getScreenByName(userName string, screenName string) (Screen, error) {

	screens, err := getRunningScreens(userName)
	if err != nil {
		return Screen{}, err
	}

	for _, screen := range screens {
		if screen.name != screenName {
			continue
		}
		return screen, nil
	}

	return Screen{}, errors.New("SCREEN_NOT_FOUND")
}