[Bug 1692353] Re: systemd-fsckd : useless CR displayed on console

[Didier Roche]

Thanks for submitting this patch and sorry for the time to review it!

The patch looks good to me, I would love though to get that directly
upstream rather than us carrying a distro-patch for a small issue like
this, do you mind doing a PR there? https://github.com/systemd/systemd/

** Changed in: systemd (Ubuntu)
       Status: Confirmed => Incomplete

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Title:
  systemd-fsckd : useless CR displayed on console

Status in systemd package in Ubuntu:
  Incomplete

Bug description:
  Hello,

  My system is "Ubuntu 16.04.2 LTS" (grep DISTRIB_DESCRIPTION /etc/lsb-
  release).

  The systemd package is installed:
    $ dpkg -l | grep systemd
    > systemd 229-4ubuntu17 

  I noticed that approximately 15 seconds after the boot, a useless
  Carriage Return ('\r') is displayed on the console (/dev/console).
  This character interacts with the display of the user currently logued in
  on the console. This screws the current line, when users is pressing keys.

  After monitoring system activity, I found the culprit:
    /lib/systemd/system/systemd-fsckd.service

  To test, run:
    service systemd-fsckd stop    # In case, it is still running.
    service systemd-fsckd start
  Go to the console, wait for approximately 15 seconds, and you see the cursor
  jumping from its current position to the beginning of the line. This is the BUG.
  Note: the console is not the X11 terminal (xterm, lxterminal, etc.) ; the
  console is the text tty reached with Control-Alt-F1.

  The systemd-fsckd.service starts the following daemon:
    /lib/systemd/systemd-fsckd
  This is the daemon which displays two useless '\r' characters.

  I went to:
    http://packages.ubuntu.com/xenial/systemd

  I downloaded:
    http://archive.ubuntu.com/ubuntu/pool/main/s/systemd/systemd_229-4ubuntu10.debian.tar.xz

  The file debian/patches/fsckd-daemon-for-inter-fsckd-communication.patch
  contains:
  +static int manager_write_console(Manager *m, const char *message) {
  [...]
  +        if (message) {
  +                fprintf(console, "\r%s\r%n", message, &l);
  +                if (m->clear  < (size_t)l)
  +                        m->clear = (size_t)l;
  +        } else {
  +                fputc('\r', console);
  +                for (j = 0; j < m->clear; j++)
  +                        fputc(' ', console);
  +                fputc('\r', console);
  +        }

  So, when no message was previously displayed, "m->clear" is still set
  to 0.

  Then, when the program ends it calls:
  +        /* clear last line */
  +        manager_write_console(m, NULL);

  However, in the "else" above, two '\r' characters are displayed, surrounding
  no space characters.

  So, when no message was previously displayed, there is nothing to clear, so
  no '\r' character to display.

  A trivial patch is attached. It is untested.

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