# apache2-maintscript-helper - Apache2 helper function for maintainer scripts
# Copyright (C) 2012 Arno Töll <debian@toell.net>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of
# this software and associated documentation files (the "Software"), to deal in
# the Software without restriction, including without limitation the rights to
# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
# the Software, and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
# FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
# COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
# IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.



#
# VARIABLES
#


# global environment variables used by apache2-maintscript-helper:
# * APACHE2_MAINTSCRIPT_DEBUG:
#				set this to any non-zero value to get debug output
# * APACHE2_MAINTSCRIPT_HELPER_QUIET:
#				set this to any non-zero value to omit any output
# * EXPORT_APACHE2_MAINTSCRIPT_HELPER:
#				will be defined by apache2-maintscript-helper
#				to avoid inclusion loops. Do not set this
#				variable manually
# * APACHE2_NEED_ACTION:
#				will be defined if a function call wants to
#				override the behavior of apache2_needs_action.
#				Do not rely on this variable. It is considered
#				an implementation detail.
# * APACHE2_MAINTSCRIPT_NAME
# * APACHE2_MAINTSCRIPT_PACKAGE
# * APACHE2_MAINTSCRIPT_METHOD
# * APACHE2_MAINTSCRIPT_ARGUMENT
#				these variables contain information about the
#				maintainer script which is calling the
#				maintscript-helper. It contains arguments which
#				dpkg supplies to maintainer scripts and similar
#				information. These variables are an
#				implementation detail and not to be changed.
#
#				You might want to set them manually only if you
#				are calling apache2-maintscript-helper from
#				some place which does not preserve the original
#				script arguments for example when calling from
#				a subfunction instead of the main function in
#				your maintainer script

#
# INITIALIZATION
#

if [ -n "${EXPORT_APACHE2_MAINTSCRIPT_HELPER:-}" ] ; then
	return
else
	EXPORT_APACHE2_MAINTSCRIPT_HELPER=1

	if [ -n "${APACHE2_MAINTSCRIPT_DEBUG:-}" ] ; then
		set -x
	elif [ -e /etc/apache2/envvars ] ; then
		APACHE2_MAINTSCRIPT_DEBUG=$(. /etc/apache2/envvars && echo ${APACHE2_MAINTSCRIPT_DEBUG})
		if [ -n "${APACHE2_MAINTSCRIPT_DEBUG:-}" ] ; then
			set -x
		fi
	fi


	if [ -z "$1" ] ; then
		echo "You must invoke apache2-maintscript-helper with an unmodified environment when sourcing it" >&2
		return 1
	fi

	APACHE2_MAINTSCRIPT_NAME="$DPKG_MAINTSCRIPT_NAME"
	[ "$APACHE2_MAINTSCRIPT_NAME" ] || APACHE2_MAINTSCRIPT_NAME="${0##*.}"

	case "$APACHE2_MAINTSCRIPT_NAME" in
		preinst|prerm|postrm|postinst)
			# yay - recognized script
		;;
		*)
			echo "apache2-maintscript-helper invoked from an unrecognized maintainer script: exiting" >&2
			return 1
		;;
	esac

	APACHE2_MAINTSCRIPT_PACKAGE="$DPKG_MAINTSCRIPT_PACKAGE"
	if [ -z "$APACHE2_MAINTSCRIPT_PACKAGE" ]; then
		APACHE2_MAINTSCRIPT_PACKAGE="${0##*/}"
		APACHE2_MAINTSCRIPT_PACKAGE="${APACHE2_MAINTSCRIPT_PACKAGE%.*}"
	fi

	if [ -z "$APACHE2_MAINTSCRIPT_METHOD" ] ; then
		APACHE2_MAINTSCRIPT_METHOD="$1"
	fi

	case "$APACHE2_MAINTSCRIPT_METHOD" in
		install|upgrade|abort-upgrade|configure|abort-remove|abort-remove|abort-deconfigure|remove|failed-upgrade|purge|disappear|abort-install|triggered)
			# yay - recognized script
		;;
		*)
			echo "apache2-maintscript-helper invoked from a modified environment. Please hint required arguments manually" >&2
			return 1
		;;
	esac



	if [ -z "$APACHE2_MAINTSCRIPT_ARGUMENT" ] ; then
		APACHE2_MAINTSCRIPT_ARGUMENT="${2:-}"
	fi

fi



#
# FUNCTIONS
#




#
# Function apache2_msg
#	print out a warning to both, the syslog and a local standard output.
#	This function should generally be used to display messages related to
#	the web server in maintainer scripts.
# Parameters:
#	priority
#		The message priority. Recognized values are the same as defined
#		by syslog(3), thus: one among debug, info, notice, warning,
#		err, crit, alert, emerg.
#		If no known priority is recognized, the priority is set to
#		"warning".
#	message
#		The message as a string. It is printed out verbatim.
# Behavior:
#	No message is displayed if APACHE2_MAINTSCRIPT_HELPER_QUIET is defined
# Returns:
#	this function always returns 0
# Since: 2.4.1-3
apache2_msg()
{
	local PRIORITY="$1"
	local MSG="$2"
	[ -z "$APACHE2_MAINTSCRIPT_HELPER_QUIET" ] && echo "$MSG" >&2
	[ -x /usr/bin/logger ] || return 0
	case "$PRIORITY" in
		debug|info|notice|warning|err|crit|alert|emerg)
		;;
		*)
			PRIORITY="warning"
		;;
	esac
	local LOGGER="/usr/bin/logger -p daemon.$PRIORITY -t $APACHE2_MAINTSCRIPT_PACKAGE "
	$LOGGER "$MSG" || return 0
}

#
# Function apache2_needs_action
#	succeeds if the package invoking the maintscript helper
#	needs any work. This function can be used as a conditional whether a
#	certain function should be executed by means of the package state.
#	Note, calling some other functions may change the outcome of this
#	function, depending on the action required
#Parameters:
#	none
# Returns:
#	0 if an older version of the maintainer script invoking the helper is
#	already installed
#	1 otherwise
# Since: 2.4.1-3
apache2_needs_action()
{
	# Summary how the maintscript behaves:
	# preinst:
	#	Not sure why anyone would like to call this function in preinst. Die loud.
	# prerm remove:
	#	Basically the same as postrm. If a maintainer would like to
	#	disable his module before removing his stuff, be it.
	#	However, we have nothing useful to do if we're called in any
	#	other way than "remove" in prerm.
	# postinst configure
	#	Probably the most important invokation. When invoked in configure we:
	#	- enable the piece of configuration on fresh installs
	#	- do nothing on upgrades UNLESS the configuration was removed automatically in the past
	# postrm remove|purge
	#	- disable the configuration, mark it as automatically disabled in remove
	#	- disable the configuration, remove any trace we have on purge

	case "$APACHE2_MAINTSCRIPT_NAME" in
	preinst)
		apache2_msg "info" "apache2_needs_action: The maintainer helper can not be called in preinst"
		return 1
		;;
	prerm|postrm)
		case "$APACHE2_MAINTSCRIPT_METHOD" in
		remove|purge)
			return 0
			;;
		*)
			return 1
			;;
		esac
		;;
	postinst)
		if [ "$APACHE2_MAINTSCRIPT_METHOD" = "configure" ] ; then
			# act on fresh installs
			[ -z "$APACHE2_MAINTSCRIPT_ARGUMENT" ] && return 0
			# act if someone told us
			[ -n "$APACHE2_NEED_ACTION" ] && return 0
		fi
		;;
	esac

	return 1
}



#
# Function apache2_has_module
#	checks whether a supplied module is enabled in the current Apache server
#	configuration
# Parameters:
#	module - the module name which should be checked. Can be a regular
#		string or a Perl compatible regular expression e.g. cgi(d|)
# Returns:
#	0 if the module(s) was/were found
#	1 otherwise
# Since: 2.4.1-1
apache2_has_module()
{
	[ -x /usr/sbin/a2query ] || return 1
	local MODULE="$1"
	if a2query -m "$MODULE" > /dev/null ; then
		return 0
	fi

	return 1
}

#
# Function apache2_switch_mpm
#	switches the MPM enabled on the web server. This function switches the
#	MPM unconditionally but does careful checks to make sure the web server
#	is left back with a working MPM.
#	It checks whether the supplied MPM exists and enables it on purpose.
# Parameters:
#	mpm - change the MPM to the supplied argument. It should be given
#	without "mpm_" prefix, e.g. "worker", "prefork", and so on.
# Returns:
#	0 if the MPM could be changed
#	1 otherwise
# Since: 2.4.1-1
apache2_switch_mpm()
{
	[ -x /usr/sbin/a2query ] || return 1
	[ -x /usr/sbin/a2dismod ] || return 1
	[ -x /usr/sbin/a2enmod ] || return 1

	local MPM="$1"
	MPM="${MPM#mpm_}"


	if [ ! -e "/etc/apache2/mods-available/mpm_$MPM.load" ] ; then
		apache2_msg "err" "apache2_switch_mpm: MPM $MPM not found"
		return 1
	fi

	local CUR_MPM=$(a2query -M) || return 1

	if [ $CUR_MPM != $MPM ] ; then
		a2dismod -m -q "mpm_$CUR_MPM";
		a2enmod -m -q "mpm_$MPM";
		apache2_msg "info" "apache2_switch_mpm Switch to $MPM"
	else
		apache2_msg "info" "apache2_switch_mpm $MPM: No action required"
		return 0
	fi

	if ! apache2_has_module "mpm_$MPM" ; then
		# rollback
		a2enmod -m -q "mpm_$CUR_MPM"
		apache2_msg "warning" "apache2_switch_mpm Switch to $MPM failed. Rolling back to $CUR_MPM"
		return 1
	fi


	APACHE2_NEED_ACTION=1
	apache2_reload restart
	return 0

}

#
# Function apache2_invoke
#	invokes an Apache 2 configuration helper to enable or disable a
#	particular piece of configuration, a site or a module. It carefully
#	checks whether the supplied configuration snippet exists and reloads the
#	web server if the site administrator desires that by calling the
#	apache2_reload function.
# Parameters:
#	command - The command to invoke. Recognized commands are "enconf",
#		"enmod", "ensite", "disconf", "dismod", "dissite"
#	arguments
#		- A single argument (e.g. a module) which shall be
#		  enabled or disabled respectively. Do not enable module
#		  dependencies that way, instead use module dependencies as
#		  documented in </usr/share/doc/apache2/PACKAGING>.
#	rcd-action
#		- An optional rc.d action to override the default which is to
#		  reload the web server for sites and configurations but restart
#		  it for modules. Recognized arguments are "restart" and "reload"
# Returns
#	0 if the changes could be activated
#	1 otherwise
# Since: 2.4.1-3
# Changes: 2.4.2-2: Added the second, optional argument
#          2.4.6-4: Allow apache2_invoke to disable configuration in preinst/postinst
apache2_invoke()
{
	local CMD=$1
	local CONF=$2
	local RCD_ACTION=$3
	local invoke_rcd=0
	local check_switch=""
	local invoke_string=""

	[ -x "/usr/sbin/a2$CMD" ] || return 1
	[ -x "/usr/sbin/a2query" ] || return 1

	case "${RCD_ACTION:-}" in
		""|reload|restart)
			;;
		*)
			return 1
			;;
	esac

	case "$CMD" in
		*conf)
			check_switch="-c"
			invoke_string="configuration"
			rcd_action="${RCD_ACTION:-reload}"
			;;
		*mod)
			check_switch="-m"
			invoke_string="module"
			rcd_action="${RCD_ACTION:-restart}"
			;;
		*site)
			check_switch="-s"
			invoke_string="site"
			rcd_action="${RCD_ACTION:-reload}"
			;;
		*)
			;;
	esac


	case "$CMD" in
		enconf|enmod|ensite)
			local a2query_ret=0
			a2query $check_switch "$CONF" > /dev/null 2>&1 || a2query_ret=$?
			if [ "$a2query_ret" -eq 0 ] ; then
				# configuration is already enabled
				apache2_msg "info" "apache2_invoke $CONF: already enabled"
				APACHE2_NEED_ACTION=1
			elif [ "$a2query_ret" -eq 32	 ] ; then
				# the maintainer disabled the module
				apache2_msg "info" "apache2_invoke $CONF: no action - $invoke_string was disabled by maintainer"
				return 0
			else
				# coming here either means:
				# a) we have no clue about the module (e.g. for upgrades prior to maintscript-helper
				# b) it's a fresh install
				APACHE2_NEED_ACTION=1
				a2$CMD -m -q "$CONF" > /dev/null 2>&1 || return 1
				apache2_msg "info" "apache2_invoke: Enable $invoke_string $CONF"
			fi
			;;
		disconf|dismod|dissite)
			local a2query_ret=0
			a2query $check_switch "$CONF" > /dev/null 2>&1 || a2query_ret=$?
			if [ "$a2query_ret" -eq 0 ] ; then
				if [ "$APACHE2_MAINTSCRIPT_NAME" = 'postrm' ] && [ "$APACHE2_MAINTSCRIPT_METHOD" = "purge" ] ; then
					a2$CMD -p -f -q "$CONF" || return 1
					apache2_msg "info" "apache2_invoke $APACHE2_MAINTSCRIPT_NAME: Purging $invoke_string $CONF"
					APACHE2_NEED_ACTION=1
				elif [ "$APACHE2_MAINTSCRIPT_NAME" = 'postrm' ] || [ "$APACHE2_MAINTSCRIPT_NAME" = 'prerm' ] ||
				    [ "$APACHE2_MAINTSCRIPT_NAME" = 'postinst' ] || [ "$APACHE2_MAINTSCRIPT_NAME" = 'preinst' ] ; then
					if [ "$APACHE2_MAINTSCRIPT_METHOD" = "remove" ] ; then
						a2$CMD -m -f -q "$CONF" || return 1
						apache2_msg "info" "apache2_invoke $APACHE2_MAINTSCRIPT_NAME: Disable $invoke_string $CONF"
						APACHE2_NEED_ACTION=1
					fi
				else
					apache2_msg "error" "apache2_invoke: $invoke_string $CONF not supported in $APACHE2_MAINTSCRIPT_NAME"
					return 1
				fi
			elif [ "$a2query_ret" -eq 32 ] || [ "$a2query_ret" -eq 33 ] ; then
				if [ "$APACHE2_MAINTSCRIPT_NAME" = 'postrm' ] && [ "$APACHE2_MAINTSCRIPT_METHOD" = "purge" ] ; then
					apache2_msg "info" "apache2_invoke $APACHE2_MAINTSCRIPT_NAME: Purging state for $CONF"
					# this will return RC=1
					( a2$CMD -p -f -q "$CONF" > /dev/null 2>&1 )
				else
					apache2_msg "info" "apache2_invoke $CONF $APACHE2_MAINTSCRIPT_NAME: No action required"
				fi
			else
				apache2_msg "info" "apache2_invoke $CONF $APACHE2_MAINTSCRIPT_NAME: No action required"
			fi
			;;
		*)
			return 1
			;;
	esac

	if [ -n "${APACHE2_NEED_ACTION:-}" ] ; then
		apache2_reload $rcd_action
	fi

}

#
# Function apache2_reload
#	reloads the web server to activate a changed configuration. It does not
#	actually reload the web server if the current configuration fails to
#	parse.
# Parameters:
#	action - optional, can be 'reload' (default) or 'restart'
# Returns:
#	0 if the changes could be activated
#	1 otherwise
# Since: 2.4.1-1
apache2_reload()
{
	if ! apache2_needs_action ; then
		return 0
	fi
	local action
	case "${1:-}" in
	""|reload)
		action=reload
		;;
	restart)
		action=restart
		;;
	*)
		return 1
		;;
	esac

	if apache2ctl configtest 2>/dev/null; then
		invoke-rc.d apache2 $action || true
	else
		apache2_msg "err" "apache2_reload: Your configuration is broken. Not ${action}ing Apache 2"
	fi
}

# vim: syntax=sh sw=8 sts=8 sr noet
