#!/bin/bash -e
#
# summary of how this script can be called:
#        * <new-preinst> install
#        * <new-preinst> install <old-version>
#        * <new-preinst> upgrade <old-version>
#        * <old-preinst> abort-upgrade <new-version>
#

# shellcheck source=/dev/null
. /usr/share/debconf/confmodule

# Just kill the invalid insserv.conf.d directory without fallback
if [ -d "/etc/insserv.conf.d/mariadb/" ]
then
  rm -rf "/etc/insserv.conf.d/mariadb/"
fi

if [ -n "$DEBIAN_SCRIPT_DEBUG" ]
then
  set -v -x
  DEBIAN_SCRIPT_TRACE=1
fi
${DEBIAN_SCRIPT_TRACE:+ echo "#42#DEBUG# RUNNING $0 $*" 1>&2 }

export PATH=$PATH:/sbin:/usr/sbin:/bin:/usr/bin
mysql_datadir=/var/lib/mysql
mysql_upgradedir=/var/lib/mysql-upgrade

MARIADBD_USERS="root"

# Check if user 'mysql' exists before referring to it in pgrep
# to avoid pgrep erroring on 'invalid user name'
if id mysql >/dev/null 2>&1
then
  MARIADBD_USERS="$MARIADBD_USERS,mysql"
fi

# Try to stop the server in a sane way. If it does not success let the admin
# do it himself. No database directories should be removed while the server
# is running! Another mariadbd in e.g. a different chroot is fine for us.
stop_server() {
  # Return immediately if there are no mysqld processes running on a host
  # (leave containerized processes with the same name in other namespaces)
  # as there is no point in trying to shutdown in that case.
  if ! pgrep -x -u "$MARIADBD_USERS" --nslist pid --ns $$ "mysqld|mariadbd" > /dev/null
  then
    return
  fi

  set +e
  invoke-rc.d mariadb stop
  invoke-rc.d mysql stop # Backwards compatibility
  errno=$?
  set -e

  # systemctl could emit exit code 100=no init script (fresh install)
  if [ "$errno" != 0 ] && [ "$errno" != 100 ]
  then
    echo "Attempt to stop MariaDB/MySQL server returned exitcode $errno" 1>&2
    echo "There is a MariaDB/MySQL server running, but we failed in our attempts to stop it." 1>&2
    echo "Stop it yourself and try again!" 1>&2
    db_stop
    exit 1
  fi
}

################################ main() ##########################

# @TODO: Rewrite this to use the new upstream /var/lib/mysql_upgrade_info file
# instead of the legacy /var/lib/debian-XX.X.flag file
this_version=__MARIADB_MAJOR_VER__
max_upgradeable_version=5.7

# Check if a flag file is found that indicates a previous MariaDB or MySQL
# version was installed. If multiple flags are found, check which one was
# the biggest version number.
for flag in "$mysql_datadir"/debian-*.flag
do

  # The for loop leaves $flag as the query string if there are no results,
  # so the check below is needed to stop further processing when there are
  # no real results.
  if [ "$flag" = "$mysql_datadir/debian-*.flag" ]
  then
    break
  fi

  # The whole flag_version thing should be rewritten, so ignore minor Shellcheck
  # nag for now
  # shellcheck disable=SC2001
  flag_version=$(echo "$flag" | sed 's/.*debian-\([0-9\.]\+\).flag/\1/')

  # Initialize value if empty
  if [ -z "$found_version" ]
  then
    found_version=$flag_version
  fi

  # Update value if now bigger then before
  if dpkg --compare-versions "$flag_version" '>>' "$found_version"
  then
    found_version=$flag_version
  fi

done


# If an upgrade is detected, proceed with it automatically without
# requiring any user interaction.
#
# However, if the user attempts to downgrade, warn about the incompatibility.
# Downgrade is detected if the flag version is bigger than $this_version
# (e.g. 10.1 > 10.0) or the flag version is smaller than 10.0 but bigger
# than $max_upgradeable_version.
if [ -n "$found_version" ]
then

  # MySQL 8.0 in Ubuntu has a bug in packaging and the file is name wrongly
  # 'debian-5.7.flag', so in case '5.7' was encountered an extra check needs to
  # be done to see is there is a file called undo_001, which is a sign of 8.0.
  if [ "$found_version" == "5.7" ] && [ -f "$mysql_datadir/undo_001" ]
  then
    # Seems to be a 8.0, flag has wrongly 5.7 (know bug)
    found_version=8.0
  fi

  echo "$mysql_datadir: found previous version $found_version"

  if dpkg --compare-versions "$found_version" '>>' "$this_version"
  then
    downgrade_detected=true
  fi

  if dpkg --compare-versions "$found_version" '>>' "$max_upgradeable_version" \
    && dpkg --compare-versions "$found_version" '<<' "10.0"
  then
    downgrade_detected=true
  fi

fi

# If there is no debian-*.flag, and no version was detected, but a file that
# indicated MySQL 8.0 is found (undo_001 is created by default in MySQL 8.0+
# installs), then that file is enough of additional indication to trigger the
# move of the data directory.
if [ -z "$found_version" ] &&
   [ -z "$(find $mysql_datadir/debian-*.flag 2> /dev/null)" ] &&
   [ -f "$mysql_datadir/undo_001" ]
then
  echo "$mysql_datadir: no server version flag found, assuming MySQL 8.0 data encountered" 1>&2
  downgrade_detected=true
  found_version="previous" # Just use dummy name as we don't know real version
fi

# Don't abort dpkg if downgrade is detected (as was done previously).
# Instead simply move the old datadir and create a new for this_version.
if [ -n "$downgrade_detected" ]
then
  db_input critical "mariadb-server/old_data_directory_saved" || true
  db_go
  echo "The contents of $mysql_datadir/ indicates a" 1>&2
  echo "version that cannot automatically be upgraded. Therefore the" 1>&2
  echo "previous data directory will be renamed to $mysql_datadir-$found_version and" 1>&2
  echo "a new data directory will be initialized at $mysql_datadir." 1>&2
  echo "Please manually export/import your data (e.g. with mysqldump) if needed." 1>&2
  mv -f "$mysql_datadir" "$mysql_datadir-$found_version"
  # Also move away the old debian.cnf file that included credentials that are
  # no longer valid. If none existed, ignore error and let dpkg continue.
  mv -f /etc/mysql/debian.cnf "/etc/mysql/debian.cnf-$found_version" || true
fi

# to be sure
stop_server

# If we use NIS then errors should be tolerated. It's up to the
# user to ensure that the mysql user is correctly setup.
# Beware that there are two ypwhich one of them needs the 2>/dev/null!
if test -n "$(command -v ypwhich 2>/dev/null)"  &&  ypwhich > /dev/null 2>&1
then
  set +e
fi

#
# Now we have to ensure the following state:
# /etc/passwd: mysql:x:100:101:MariaDB Server:/nonexistent:/bin/false
# /etc/group:  mysql:x:101:
#
# Sadly there could any state be present on the system so we have to
# modify everything carefully i.e. not doing a chown before creating
# the user etc...
#

# creating mysql group if he isn't already there
if ! getent group mysql >/dev/null
then
  # Adding system group: mysql.
  addgroup --system mysql >/dev/null
fi

# creating mysql user if he isn't already there
if ! getent passwd mysql >/dev/null
then
  # Adding system user: mysql.
  adduser \
    --system \
    --disabled-login \
    --ingroup mysql \
    --no-create-home \
    --home /nonexistent \
    --gecos "MariaDB Server" \
    --shell /bin/false \
    mysql >/dev/null 2>&1
fi

# end of NIS tolerance zone
set -e

# if there's a symlink, let's store where it's pointing, because otherwise
# it's going to be lost in some situations
for dir in DATADIR LOGDIR
do
  checkdir=$(eval echo "$"$dir)
  if [ -L "$checkdir" ]
  then
    # Use mkdir option 'Z' to create with correct SELinux context.
    mkdir -pZ "$mysql_upgradedir"
    cp -dT "$checkdir" "$mysql_upgradedir/$dir.link"
  fi
done

# creating mysql home directory
if [ ! -d $mysql_datadir ] && [ ! -L $mysql_datadir ]
then
  # Use mkdir option 'Z' to create with correct SELinux context.
  mkdir -Z $mysql_datadir
fi

# As preset blocksize of GNU df is 1024 then available bytes is $df_available_blocks * 1024
# 4096 blocks is then lower than 4 MB
df_available_blocks="$(LC_ALL=C BLOCKSIZE='' df --output=avail "$mysql_datadir" | tail -n 1)"
if [ "$df_available_blocks" -lt "4096" ]
then
  echo "ERROR: There's not enough space in $mysql_datadir/" 1>&2
  db_stop
  exit 1
fi

# Since the home directory was created before putting the user into
# the mysql group and moreover we cannot guarantee that the
# permissions were correctly *before* calling this script, we fix them now.
# In case we use NIS and no mysql user is present then this script should
# better fail now than later..
# The "set +e" is necessary as e.g. a ".journal" of a ext3 partition is
# not chgrp'able (#318435).
set +e
find $mysql_datadir ! -uid "$(id -u mysql)" -print0 | xargs -0 -r chown mysql
find $mysql_datadir -follow -not -group mysql -print0 2>/dev/null \
  | xargs -0 --no-run-if-empty chgrp mysql
set -e

db_stop

#DEBHELPER#

# dh_installinit/13.11.3 adds this check but only with 'install', so we need to
# have and extra one to check 'upgrade'. This ensures that upgrades from
# mariadb-server-x.y to mariadb-server (without version suffix) ends up with
# the executable bit set on /etc/init.d/mariadb, which otherwise would end up
# disabled due to the mariadb-server-x.y.postrm being triggered.
#   $1 = upgrade
#   $2 = 1:10.6.11-2
if [ "$1" = "upgrade" ] && [ -n "$2" ] && [ -e "/etc/init.d/mariadb" ]
then
  chmod +x "/etc/init.d/mariadb" >/dev/null || true
fi

# dh_installinit/13.11.3 adds this check but with extra condition that there
# must be a version passed as '$2', but that will always be empty when install
# runs after the unpack that is retriggered for package 'mariadb-server' when
# the old 'mariadb-server-10.6' is purged, so we need to repeat the same check
# here without any expectation for '$2'. This ensures that upgrades from
# mariadb-server-x.y to mariadb-server (without version suffix) ends up with the
# executable bit set on /etc/init.d/mariadb.
if [ "$1" = "install" ] && [ -e "/etc/init.d/mariadb" ]
then
  chmod +x "/etc/init.d/mariadb" >/dev/null || true
fi