Function copyStderr

cmd/syncthing/monitor.go:217–264

(stderr io.Reader, dst io.Writer)

}

func copyStderr(stderr io.Reader, dst io.Writer) {
	br := bufio.NewReader(stderr)

	var panicFd *os.File
	defer func() {
		if panicFd != nil {
			_ = panicFd.Close()
			maybeReportPanics()
		}
	}()

	for {
		line, err := br.ReadString('\n')
		if err != nil {
			return
		}

		dst.Write([]byte(line))

		if panicFd == nil && (strings.HasPrefix(line, "panic:") || strings.HasPrefix(line, "fatal error:") || strings.HasPrefix(line, "runtime:")) {
			panicFd, err = os.Create(locations.GetTimestamped(locations.PanicLog))
			if err != nil {
				slog.Error("Failed to create panic log", slogutil.Error(err))
				continue
			}

			slog.Error("Panic detected, writing to file", slogutil.FilePath(panicFd.Name()))
			slog.Info("Please check for existing issues with similar panic message at https://github.com/syncthing/syncthing/issues/")
			slog.Info("If no issue with similar panic message exists, please create a new issue with the panic log attached")

			stdoutMut.Lock()
			for _, line := range stdoutFirstLines {
				panicFd.WriteString(line)
			}
			panicFd.WriteString("...\n")
			for _, line := range stdoutLastLines {
				panicFd.WriteString(line)
			}
			stdoutMut.Unlock()

			panicFd.WriteString("Panic at " + time.Now().Format(time.RFC3339) + "\n")
		}

		if panicFd != nil {
			panicFd.WriteString(line)
		}
	}
}

func copyStdout(stdout io.Reader, dst io.Writer) {
	br := bufio.NewReader(stdout)