#!/bin/bash
#
# 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>
#

set -e

. /usr/share/debconf/confmodule

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
MYADMIN="/usr/bin/mysqladmin --defaults-file=/etc/mysql/debian.cnf"
DATADIR=/var/lib/mysql
LOGDIR=/var/log/mysql
UPGRADEDIR=/var/lib/mysql-upgrade

# To avoid having hardcoded paths in the script, we do a search on the path, as suggested at:
# https://www.debian.org/doc/manuals/developers-reference/ch06.en.html#bpp-debian-maint-scripts
pathfind() {
  OLDIFS="$IFS"
  IFS=:
  for p in $PATH; do
    if [ -x "$p/$*" ]; then
      IFS="$OLDIFS"
      return 0
    fi
  done
  IFS="$OLDIFS"
  return 1
}

# 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 mysqld in e.g. a different chroot is fine for us.
stop_server() {
    if [ ! -x /etc/init.d/mysql ]; then return; fi

    set +e
    if pathfind invoke-rc.d; then
      cmd="invoke-rc.d mysql stop"
    else
      cmd="/etc/init.d/mysql stop"
    fi
    $cmd
    errno=$?
    set -e
   
    # 0=ok, 100=no init script (fresh install)
    if [ "$errno" != 0 -a "$errno" != 100 ]; then
      echo "${cmd/ */} returned $errno" 1>&2
      echo "There is a 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() ##########################

this_version=5.7

# Abort if an NDB cluster is in use.
if egrep -qi -r '^[^#]*ndb.connectstring|^[[:space:]]*\[[[:space:]]*ndb_mgmd' /etc/mysql/; then
  db_fset mysql-server/no_upgrade_when_using_ndb seen false || true
  db_input high mysql-server/no_upgrade_when_using_ndb || true
  db_go
  db_stop
  exit 1
fi

# Abort if skip-bdb option is enabled, required for 5.0 -> 5.1 upgrades.
#TODO

# Safe the user from stupidities.
is_downgrade_attempt=0
for i in `ls $DATADIR/debian-*.flag 2>/dev/null`; do
  found_version=`echo $i | sed 's/.*debian-\([0-9\.]\+\).flag/\1/'`
  if dpkg --compare-versions "$this_version" '<<' "$found_version"; then
    is_downgrade_attempt=1
    break;
  fi
done
if [ "$is_downgrade_attempt" = 1 ]; then
  echo "Downgrade from (at least) $found_version to $this_version is not possible." 1>&2
  if [ -e /etc/mysql/FROZEN -o -h /etc/mysql/FROZEN ]; then
    echo "Warning: /etc/mysql/FROZEN already exists" >&2
  else
    ln -s ../../usr/share/doc/mysql-common/frozen-mode/downgrade /etc/mysql/FROZEN
  fi
fi

if [ -e /etc/mysql/FROZEN -o -h /etc/mysql/FROZEN ]; then
  error_message="MySQL has been frozen to prevent damage to your system. Please see /etc/mysql/FROZEN for help."
  logger -p daemon.err -t /etc/init.d/mysql -i "$error_message"
  db_fset mysql-server-$this_version/installation_freeze_mode_active seen false || true
  db_input critical mysql-server-$this_version/installation_freeze_mode_active || true
  db_go
  db_stop
  echo "$error_message" 1>&2
  exit 0
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 "`which 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:MySQL 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 "MySQL Server" \
	  --shell /bin/false \
	  mysql  >/dev/null
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 "$checkdir" ]; then
	mkdir -p "$UPGRADEDIR"
	cp -dT "$checkdir" "$UPGRADEDIR/$dir.link"
    fi
done

# creating mysql home directory
if [ ! -d $DATADIR -a ! -L $DATADIR ]; then
 	mkdir $DATADIR
fi

# checking disc space
if LC_ALL=C BLOCKSIZE= df --portability $DATADIR/. | tail -n 1 | awk '{ exit ($4>1000) }'; then
  echo "ERROR: There's not enough space in $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
chown mysql:mysql $DATADIR
find $DATADIR -follow -not -group mysql -print0 2>/dev/null \
  | xargs -0 --no-run-if-empty chgrp mysql
set -e


db_stop

# Automatically added by dh_installinit/13.15.1
if [ "$1" = "install" ] && [ -n "$2" ] && [ -e "/etc/init.d/mysql" ] ; then
	chmod +x "/etc/init.d/mysql" >/dev/null || true
fi
# End automatically added section


exit 0