garbled recovery mode in Simplified Chinese language OS install

Using root shell, I can reproduce the problem using the command line (not only reproducible in the dialog window)

Here's the system variable right after booting in Recovery mode took from the root shell option.

---
$ echo $LANG
zh_CN.UTF-8

$ echo $LANGUAGE
zh_CN:zh
---

If I change manually the system variables as follow :

--
export LANG=C.UTF-8
export LANGUAGE=en
---

The situation disappear.

friendly-recovery have a blacklist including a detection for "zh_" mechanism but doesn't seems to default $LANG and $LANGUAGE to good working console value to avoid this situation to happen with CJK font.

I have tested the following approach and it works by displaying in english when detect a known font which have not a good console output.

--
# blacklist some languages that we don't have a good console fonts for
# see bug #573502
in_lang_blacklist() {
    LANG_BLACKLIST="ar_ he_IL ja_JP ko_KR ru_RU sl_SI vi_VN zh_"
    LANG=$1
    for b in $LANG_BLACKLIST; do
        # equal to lang.startswith(b)
        if expr match "$LANG" ^"$b" >/dev/null ; then
+ export LANG=C.UTF-8
+ export LANGUAGE=en
            return 0
        fi
    done
    return 1
}

# There is no environment set, as these steps are skipped,
# so we need to source the variables needed for localization ourselves
if [ -r /etc/default/locale ]; then
 . /etc/default/locale
 if ! in_lang_blacklist "$LANG"; then
     export LANG LANGUAGE
 fi
elif [ -r /etc/environment ]; then
 . /etc/environment
 if ! in_lang_blacklist "$LANG"; then
     export LANG LANGUAGE
 fi
fi

. gettext.sh
export TEXTDOMAIN=friendly-recovery
export TEXTDOMAINDIR=/usr/share/locale
---

Example of the recovery mode with zh_CN.UTF-8 (which is 1 of the blacklisted language)

debdiff for devel release (bionic)

mvo uploaded the fix a few minutes ago.

This bug was fixed in the package friendly-recovery - 0.2.37ubuntu1

---------------
friendly-recovery (0.2.37ubuntu1) bionic; urgency=medium

  * /lib/recovery-mode/l10n.sh (LP: #1752362)
    - Default to LANG "C.UTF-8" and LANGUAGE "en" when locales are part
      of a language blacklist which doesn't have a good console fonts.

 -- Eric Desrochers <email address hidden> Wed, 28 Feb 2018 11:26:37 -0500

debdiff for xenial

debdiff for artful

Uploaded for Xenial and Artful.
Trusty is not affected.

Hello Eric, or anyone else affected,

Accepted friendly-recovery into artful-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/friendly-recovery/0.2.36ubuntu1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-artful to verification-done-artful. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-artful. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

Hello Eric, or anyone else affected,

Accepted friendly-recovery into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/friendly-recovery/0.2.31ubuntu1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[VERIFICATION XENIAL]

I confirmed after having tested friendly-recovery version 0.2.31ubuntu1 for Xenial in Recovery mode, that the proposed package default to English on a Chinese installation where the system variable $LANG is part of the language blacklist.

(See "Bug attachment" for a screenshot)

[VERIFICATION ARTFUL]

I confirmed after having tested friendly-recovery version 0.2.36ubuntu1 for Artful in Recovery mode, that the proposed package default to English on a Chinese installation where the system variable $LANG is part of the language blacklist.

(See "Bug attachment" for a screenshot)

This bug was fixed in the package friendly-recovery - 0.2.36ubuntu1

---------------
friendly-recovery (0.2.36ubuntu1) artful; urgency=medium

  * /lib/recovery-mode/l10n.sh (LP: #1752362)
    - Default to LANG "C.UTF-8" and LANGUAGE "en" when locales are part
    of a language blacklist which doesn't have a good console fonts.

 -- Eric Desrochers <email address hidden> Wed, 28 Feb 2018 15:24:29 -0500

The verification of the Stable Release Update for friendly-recovery has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

This bug was fixed in the package friendly-recovery - 0.2.31ubuntu1

---------------
friendly-recovery (0.2.31ubuntu1) xenial; urgency=medium

  * /lib/recovery-mode/l10n.sh (LP: #1752362)
    - Default to LANG "C.UTF-8" and LANGUAGE "en" when locales are part
    of a language blacklist which doesn't have a good console fonts.

 -- Eric Desrochers <email address hidden> Wed, 28 Feb 2018 15:23:43 -0500

It has been brought to my attention the following as well from another user:

"
... below is our team verified and issue not repro with package installed. Thanks.
The issue is NOT reproducible with the package(friendly-recovery_0.2.37ubuntu1).
"