package main import ( "bufio" "errors" "fmt" "os" "os/exec" "os/user" "strconv" "strings" "syscall" ) // Very simple and limited .env file reader. // All variable definitions found are directly // added to the processes environment. func loadEnv(file string) error { f, err := os.Open(file) if err != nil { return err } defer f.Close() s := bufio.NewScanner(bufio.NewReader(f)) for s.Scan() { line := s.Text() if strings.HasPrefix(line, "#") || len(line) == 0 { continue } if strings.Contains(line, "#") { return errors.New("'#' are only supported at the start of a line") } line = strings.TrimPrefix(line, "export ") parts := strings.SplitN(line, "=", 2) if len(parts) != 2 { return fmt.Errorf("unsupported line: %#v", line) } key := strings.TrimSpace(parts[0]) val := strings.TrimSpace(parts[1]) if strings.HasPrefix(val, "\"") { if !strings.HasSuffix(val, "\"") { return fmt.Errorf("unsupported line: %#v", line) } runes := []rune(val[1 : len(val)-1]) sb := strings.Builder{} for i := 0; i < len(runes); i++ { if runes[i] == '\\' { i++ switch runes[i] { case 'n': sb.WriteRune('\n') case 'r': sb.WriteRune('\r') case 't': sb.WriteRune('\t') case '"': sb.WriteRune('"') default: return fmt.Errorf("unsupprorted escape sequence in quoted string: backslash %#v", runes[i]) } continue } sb.WriteRune(runes[i]) } val = sb.String() } os.Setenv(key, val) } return s.Err() } // Changes the processes user and group to that // specified in the config.json. The go runtime // takes care of all threads (and not only the calling one) // executing the underlying systemcall. func dropPrivileges() error { if programConfig.Group != "" { g, err := user.LookupGroup(programConfig.Group) if err != nil { return err } gid, _ := strconv.Atoi(g.Gid) if err := syscall.Setgid(gid); err != nil { return err } } if programConfig.User != "" { u, err := user.Lookup(programConfig.User) if err != nil { return err } uid, _ := strconv.Atoi(u.Uid) if err := syscall.Setuid(uid); err != nil { return err } } return nil } // If started via systemd, inform systemd that we are running: // https://www.freedesktop.org/software/systemd/man/sd_notify.html func systemdNotifiy(ready bool, status string) { if os.Getenv("NOTIFY_SOCKET") == "" { // Not started using systemd return } args := []string{fmt.Sprintf("--pid=%d", os.Getpid())} if ready { args = append(args, "--ready") } if status != "" { args = append(args, fmt.Sprintf("--status=%s", status)) } cmd := exec.Command("systemd-notify", args...) cmd.Run() // errors ignored on purpose, there is not much to do anyways. }