Change maintainer scripts to support multiple web servers and versions of.

A side effect of the above is the spinoff of a reausable by other packages
maintainer scripts library.

6 files changed, 780 insertions, 70 deletions

diff --git a/debian/dirs b/debian/dirs
index 085a044..66e7552 100644
--- a/debian/dirs
+++ b/debian/dirs
@@ -1,4 +1,7 @@
+usr/share/doc/HTML
 var/lib/dhelp
 var/lib/dhelp/tmp
-var/www/doc
-etc/apt/apt.conf.d
+/etc/apt/apt.conf.d
+/etc/apache2/conf.d
+/etc/apache2/conf-available
+/etc/lighttpd/conf-available
diff --git a/debian/postinst b/debian/postinst
index 758f432..e510981 100755
--- a/debian/postinst
+++ b/debian/postinst
@@ -1,6 +1,8 @@
-#!/bin/sh -e 
+#!/bin/sh
 #
-# Copyright 2001,2002 by Stefan Hornburg (Racke) <racke@linuxia.de>
+# Copyright (C) 2001,2002 Stefan Hornburg (Racke) <racke@linuxia.de>
+# Copyright (C) 2007 Esteban Manchado Velázquez <zoso@debian.org>
+# Copyright (C) 2011,2012 Georgios M. Zarkadas <gz@member.fsf.org>
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -17,69 +19,188 @@
 # Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 # MA  02111-1307  USA.
 
-# create /var/lib/dhelp if necessary
-if [ ! -d /var/lib/dhelp ]; then
-    mkdir /var/lib/dhelp
-fi
+set -e
 
-# remove /usr/doc/HTML2 if upgrading from old dhelp package
-if [ "$1" = configure -a -d /usr/doc/HTML2 ]; then
-    rm -rf /usr/doc/HTML2
-fi
-
-# remove old /var/lib/dhelp/swish++.index (versions older than 0.6)
-rm -f /var/lib/dhelp/swish++.index
+#DEBHELPER#
 
-# hack to be able to tell if the package is configured, so 3rd party packages
-# that call dhelp don't barf (from scrollkeeper package)
-touch /var/lib/dhelp/configured
+#### Globals ####
 
 DHELP_INDEXER=/usr/share/dhelp/scripts/index-deferred
 DHELP_APTHOOK=/etc/apt/apt.conf.d/35dhelp
+DHELP_POSTCMD='Dpkg::Post-Invoke {
+    "if test -x '${DHELP_INDEXER}'; then '${DHELP_INDEXER}'; fi";
+};'
+DHELP_CONFDIR=/usr/share/dhelp/config
+DHELP_OKINDEX="false"
+
+#### Import Library ####
+
+for DHELP_LIBFILE in /usr/share/dhelp/maint-scripts/*.sh; do 
+    if [ -f ${DHELP_LIBFILE} ]; then
+        . ${DHELP_LIBFILE}
+    else
+        >&2 echo "Dhelp error: file ${DHELP_LIBFILE} was not found."
+        >&2 echo "Please file a bug report at bugs.debian.org" \
+            "against the dhelp package."
+    fi
+done
+
+#### Functions ####
+
+# cleanup artifacts of previous versions
+#
+do_upgrade_cleanup_actions ()
+{
+    # remove /usr/doc/HTML, /usr/doc/HTML2 and /usr/doc/dhelp
+    # if upgrading from old dhelp package
+
+    if [ -h /usr/doc/HTML ]; then
+        rm --force /usr/doc/HTML
+    elif [ -d /usr/doc/HTML ]; then
+        rm --force --recursive /usr/doc/HTML
+    fi
+
+    if [ -d /usr/doc/HTML2 ]; then
+        rm --force --recursive /usr/doc/HTML2
+    fi
+
+    if [ -h /usr/doc/dhelp ]; then
+        rm --force /usr/doc/dhelp
+    fi
+
+    # remove old /var/lib/dhelp/swish++.index (versions older than 0.6)
+
+    if [ ! -d /var/lib/dhelp/swish++.index ]; then
+        rm --force /var/lib/dhelp/swish++.index
+    fi
+}
 
 # create and register with ucf our dpkg post-invoke hook
+#
+register_dpkg_postinvoke_hook ()
+{
+    local dhelp_tmp_apthook=$(mktemp)
+
+    chmod 644 ${dhelp_tmp_apthook}
+    echo "${DHELP_POSTCMD}" > ${dhelp_tmp_apthook}
+
+    mv_ucfregister_file dhelp ${dhelp_tmp_apthook} ${DHELP_APTHOOK}
+}
 
-DHELP_POSTCMD="\"if test -x ${DHELP_INDEXER}; then ${DHELP_INDEXER}; fi\""
-DHELP_TMP_APTHOOK=`mktemp 2>/dev/null`
-if [ $? -ne 0 ]; then
-    >&2 echo "Error: unable to create temporary file"
-    exit 1
-fi
-if ! chmod 644 ${DHELP_TMP_APTHOOK}; then
-    >&2 echo "Error: unable to change mode of temporary file"
-    exit 2
-fi
-echo "Dpkg::Post-Invoke { ${DHELP_POSTCMD}; };" > ${DHELP_TMP_APTHOOK}
-
-ucf --debconf-ok --three-way ${DHELP_TMP_APTHOOK} ${DHELP_APTHOOK}
-rm -f ${DHELP_TMP_APTHOOK}
-ucfr dhelp ${DHELP_APTHOOK}
-
-# create /var/www/doc if necessary
-if [ ! -d /var/www/doc ]; then
-    mkdir /var/www/doc
-fi
-
-# 'dhelp_parse -r', among other actions, produces the pending list.
-echo -n "Building HTML tree..."
-dhelp_parse -r
-echo " done."
-
-# symlink /usr/share/doc/{dhelp,HTML} from /var/www/doc
-ln -s /usr/share/doc/dhelp /var/www/doc/dhelp
-ln -s /usr/share/doc/HTML /var/www/doc/HTML
-
-# Thus, if index file does not exist, it suffices to do incremental indexing.
-if [ ! -f /var/lib/dhelp/documents.index ]; then
-    echo "Reindexing documentation in the background"
-    if [ -x ${DHELP_INDEXER} ]; then
-        ${DHELP_INDEXER}
+# build the set of html files inside /usr/share/doc/HTML 
+#
+build_document_index ()
+{
+    local ret=0
+
+    # 'dhelp_parse -r', among other actions, produces the pending list.
+    echo -n "Building HTML tree..."
+
+    dhelp_parse -r && ret=$? || ret=$?
+
+    if [ ${ret} -eq 0 ]; then
+        echo " done."
+    fi
+    return ${ret}
+}
+
+# create the full text search index file in the background
+#
+delaybuild_search_index ()
+{
+    local ret=0
+
+    # since the pending list is created by dhelp_parse -r, if index file
+    # does not exist, it suffices to do incremental indexing.
+
+    if [ -f /var/lib/dhelp/documents.index ]; then
+        return 0
     else
-        >&2 echo "Error: ${DHELP_INDEXER} does not exist or is not executable"
-        exit 3
+        echo "Reindexing documentation in the background"
+
+        if [ -x ${DHELP_INDEXER} ]; then
+            ${DHELP_INDEXER} && ret=$? || ret=$?
+            return ${ret}
+        else
+            install_msg dhelp err \
+                "Error: ${DHELP_INDEXER} does not exist or is not executable"
+            return 1
+        fi
     fi
-fi
+}
 
-unset DHELP_INDEXER DHELP_POSTCMD DHELP_APTHOOK DHELP_TMP_APTHOOK || true
+#### Main script body ####
+
+# NOTE: do not fail package installation if "cache data" that can be
+# recreated anytime cannot for any reason be created during install.
+
+case $1 in
+configure|abort-upgrade)
+
+    # cleanup artifacts of previous versions
+
+    do_upgrade_cleanup_actions
+
+    # Create and register with ucf our dpkg post-invoke hook.
+
+    register_dpkg_postinvoke_hook
+
+    # Hack to tell if the package is configured, so that third party 
+    # packages that call dhelp don't barf (from scrollkeeper package).
+    # It is also checked by dhelp_parse, hence this line must come
+    # _before_ the build_document_index call.
+
+    touch /var/lib/dhelp/configured
+
+    # Create the html document index before registering configuration
+    # snippets with installed web servers.
+
+    if build_document_index; then
+        DHELP_OKINDEX="true"
+    else
+        install_msg dhelp err \
+            "Error: building of the HTML tree failed;" \
+            "check mount options and disk space for '/usr/share/doc/HTML'" \
+            "and run 'dhelp_parse -r' to retry the build process."
+    fi
+
+    # Apache2: copy in both locations, ie for versions < 2.4 and >= 2.4
+
+    cp_ucfregister_file dhelp ${DHELP_CONFDIR}/apache-dhelp.conf \
+        /etc/apache2/conf.d/dhelp
+    cp_ucfregister_file dhelp ${DHELP_CONFDIR}/apache-dhelp.conf \
+        /etc/apache2/conf-available/dhelp.conf
+
+    try_chconf_apache2 "enable"  dhelp || true
+
+    # Lighttpd: 
+
+    cp_ucfregister_file dhelp ${DHELP_CONFDIR}/lighttpd-dhelp.conf \
+        /etc/lighttpd/conf-available/95-dhelp.conf
+
+    try_chconf_lighttpd "enable" dhelp || true
+
+    # Create the full text search index at the end of postinst.
+
+    if [ "${DHELP_OKINDEX}" = "true" ]; then
+        if delaybuild_search_index; then
+            :
+        else
+            install_msg dhelp err \
+                "Error: delayed indexing failed;" \
+                "run the weekly cron job to recreate the index."
+        fi
+    else
+        install_msg dhelp warning \
+            "Not reindexing documentation due to HTML tree" \
+            "build error; correct the above and run the weekly" \
+            "cron job to recreate the index."
+    fi
+    ;;
+*)
+    ;;
+esac
+
+unset DHELP_INDEXER DHELP_POSTCMD DHELP_APTHOOK || true
+unset DHELP_CONFDIR DHELP_LIBFILE DHELP_OKINDEX || true
 
-#DEBHELPER#
diff --git a/debian/prerm b/debian/prerm
index 1327bfb..07cf3be 100755
--- a/debian/prerm
+++ b/debian/prerm
@@ -1,18 +1,118 @@
-#!/bin/sh -e
+#!/bin/sh
+#
+# Copyright (C) 2001,2002 Stefan Hornburg (Racke) <racke@linuxia.de>
+# Copyright (C) 2011,2012 Georgios M. Zarkadas <gz@member.fsf.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public
+# License along with this program; if not, write to the Free
+# Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+# MA  02111-1307  USA.
+
+set -e
 
 #DEBHELPER#
 
-rm -rf /var/lib/dhelp
-rm -rf /usr/doc/HTML /usr/share/doc/HTML
-rm -f /var/lib/dhelp/configured
+#### Globals ####
+
+DHELP_APTHOOK=/etc/apt/apt.conf.d/35dhelp
+
+#### Import Library ####
+
+# If old version's prerm fails, our files (and thus the script library)
+# will not be available. Thus, we need to treat this case specially.
+
+case $1 in
+failed-upgrade)
+    ;;
+*)
+    for DHELP_LIBFILE in /usr/share/dhelp/maint-scripts/*.sh; do 
+        if [ -f ${DHELP_LIBFILE} ]; then
+            . ${DHELP_LIBFILE}
+        else
+            >&2 echo "Dhelp error: file ${DHELP_LIBFILE} was not found."
+            >&2 echo "Please file a bug report at bugs.debian.org" \
+                "against the dhelp package."
+        fi
+    done
+    ;;
+esac
+
+#### Functions ####
+
+# Cleanup the files installed by the postinst.
+#
+do_removal_cleanup_actions ()
+{
+    # The directories themselves will be removed by dpkg;
+    # cf. our debian/dirs entries.
+
+    # Remove all cache data inside /var/lib/dhelp/tmp
+
+    if [ -d /var/lib/dhelp/tmp ]; then
+        rm --force /var/lib/dhelp/tmp/* || true
+    fi
+
+    # Remove all cache data inside /var/lib/dhelp
+    # Hide the "rm: cannot remove `/var/lib/dhelp/tmp': Is a directory" error.
+
+    if [ -d /var/lib/dhelp ]; then
+        rm --force /var/lib/dhelp/* 2>&1 \
+            | grep --invert-match '/var/lib/dhelp/tmp' || true
+    fi
+
+    # Remove html document index directory contents.
+
+    if [ -d /usr/share/doc/HTML ]; then
+        rm --force --recursive /usr/share/doc/HTML/*
+    fi
+}
+
+#### Main script body ####
+
+case $1 in
+failed-upgrade)
+    # Library is not available; confine ourselves to the bare essentials.
+
+    do_removal_cleanup_actions
+    ;;
+*)
+    # Disable our web server configuration snippets.
+
+    try_chconf_apache2  "disable" dhelp || true
+    try_chconf_lighttpd "disable" dhelp || true
+
+    # Cleanup the files installed by the postinst.
+
+    do_removal_cleanup_actions
+    ;;
+esac
+
+case $1 in
+purge)
+    # Remove and unregister with ucf our web server configuration snippets.
+
+    ucf_unregister_file dhelp /etc/apache2/conf.d/dhelp
+    ucf_unregister_file dhelp /etc/apache2/conf-available/dhelp.conf
+
+    ucf_unregister_file dhelp /etc/lighttpd/conf-available/95-dhelp.conf
+
+    # Remove and unregister with ucf our dpkg post-invoke hook.
 
-if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
-     -a -L /usr/doc/dhelp ]; then
-  rm -f /usr/doc/dhelp
-fi
+    ucf_unregister_file dhelp ${DHELP_APTHOOK}
+    ;;
+*)
+    ;;
+esac
 
+unset DHELP_APTHOOK DHELP_LIBFILE || true
 
-if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
-     -a -L /usr/doc/HTML ]; then
-  rm -f /usr/doc/HTML
-fi
diff --git a/debian/scripts/files.sh b/debian/scripts/files.sh
new file mode 100644
index 0000000..aa038fc
--- /dev/null
+++ b/debian/scripts/files.sh
@@ -0,0 +1,139 @@
+# File operation functions for Debian maintainer scripts.
+# Copyright (C) 2012 Georgios M. Zarkadas <gz@member.fsf.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public
+# License along with this program; if not, write to the Free
+# Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+# MA  02111-1307  USA.
+#
+# This file is intended to be sourced by maintainer scripts.
+
+
+# Test executability (implies existence) of a binary in the system's path.
+# ARGS:
+# $1=binary_basename
+#
+is_exec()
+{
+    # First ensure we are not passed an empty argument,
+    # because test -x "" returns success.
+
+    if [ "X${1}" = "X" ]; then
+        return 2
+    fi
+
+    # Then look for the binary location. If not found,
+    # return error, because test -x "" returns success.
+
+    local binary=$(which "${1}" 2>/dev/null)
+
+    if [ "X${binary}" = "X" ]; then
+        return 1
+    fi
+
+    # If the binary is found, return its executable status.
+
+    test -x "${binary}" 2>/dev/null
+}
+
+
+# Ucf-interfacing of generated conffiles helpers.
+# Fall-through behaviour, when ucf is not available:
+# -- install our version of the conffile
+# -- if old conffile exists and is a file, rename old conffile to 
+#    <conffile>.ucf-old
+# -- if old conffile or <conffile>.ucf-old exists and is a directory,
+#    fail. 
+
+# Copy a conffile to the filesystem and add it to the ucf and ucfr databases.
+# ARGS:
+# $1=package $2=source $3=destination
+#
+cp_ucfregister_file ()
+{
+    local package="${1}"
+    local srcfile="${2}"
+    local conffile="${3}"
+
+    if is_exec ucf; then
+        ucf --debconf-ok --three-way "${srcfile}" "${conffile}"
+    else
+        # If conffile is a symlink, our move-to-old-then-copy strategy
+        # would make the symlink a normal file; account for this.
+
+        if [ -h "${conffile}" ]; then
+
+            local realconf=$(readlink --no-newline \
+                --canonicalize "${conffile}" || :)
+
+            if [ "X${realconf}" = "X" ]; then
+                >&2 echo "${conffile} is a broken symlink; replacing it"
+                rm --force "${conffile}"
+            else
+                conffile="${realconf}"
+            fi
+        fi
+
+        # Now, after resolving symlinks, check for existence and being a file.
+
+        if [ -e "${conffile}" ]; then
+            if [ -d "${conffile}" ] || [ -d "${conffile}.ucf-old" ]; then
+                >&2 echo "${conffile} is a directory; aborting"
+                return 10
+            fi
+            # We do not use the backup option, because in such a case
+            # we would being accumulating backups on each upgrade.
+
+            mv --force "${conffile}" "${conffile}.ucf-old"
+        fi
+        cp --force --preserve "${srcfile}" "${conffile}"
+    fi
+
+    if is_exec ucfr; then
+        ucfr "${package}" "${conffile}"
+    fi
+}
+
+# Move a (temporary, ie dynamically created) conffile to the filesystem
+# and add it to the ucf and ucfr databases.
+# 
+# $1=package $2=source $3=destination
+#
+mv_ucfregister_file ()
+{
+    cp_ucfregister_file "${1}" "${2}" ${3}
+    rm --force "${2}"
+}
+
+# Remove a conffile from the filesystem and the ucf and ucfr databases.
+# ARGS: 
+# $1=package $2=conffile
+#
+ucf_unregister_file ()
+{
+    local package="${1}"
+    local conffile="${2}"
+    local ext
+
+    # the '' value is to delete the file itself
+    for ext in '' '~' '%' .bak .ucf-new .ucf-old .ucf-dist; do
+        rm -f "${conffile}${ext}" || true
+    done
+    if is_exec ucf; then
+        ucf --purge "${conffile}"
+    fi
+    if is_exec ucfr; then
+        ucfr --purge "${package}" "${conffile}"
+    fi
+}
+
diff --git a/debian/scripts/httpd.sh b/debian/scripts/httpd.sh
new file mode 100644
index 0000000..6fe318c
--- /dev/null
+++ b/debian/scripts/httpd.sh
@@ -0,0 +1,263 @@
+# httpd configuration enable/disable functions for Debian maintainer scripts.
+# Copyright (C) 2012 Georgios M. Zarkadas <gz@member.fsf.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public
+# License along with this program; if not, write to the Free
+# Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+# MA  02111-1307  USA.
+#
+# This file is intended to be sourced by maintainer scripts.
+
+# REQUIRES: info.sh files.sh
+
+# (internal) message template functions
+
+# ARGS:
+# $1=package $2=caller
+#
+_httpdmsg_nocfa()
+{
+    echo "${1} error: invalid action '${2}' supplied as argument"
+}
+
+# ARGS:
+# $1=caller_with_args
+#
+_httpdmsg_nopkg()
+{
+    echo "${1} error: package name was not supplied as argument"
+}
+
+# ARGS:
+# $1=package $2=httpd_name $3={enable,disable}
+#
+_httpdmsg_check()
+{
+    local text=""
+    if [ "${3}" = "disable" ]; then
+        text="de"
+    fi
+    echo "check the status of the ${2} web server and whether" \
+        "${1} configuration for ${2} has been ${text}activated."
+}
+
+# ARGS:
+# $1=package $2=httpd_name $3={enable,disable}
+#
+_httpdmsg_noact()
+{
+    local text=""
+    if [ "${3}" = "disable" ]; then
+        text="de"
+    fi
+    echo "${1} configuration for ${2} has not been ${text}activated."
+}
+
+# Return error if action is not (en/dis)able or package is empty.
+# ARGS:
+# $1=action $2=package $3=caller
+#
+_check_action_and_package()
+{
+    local action=${1}
+    local package=${2}
+    local caller=${3}
+
+    local nopkg="false"
+
+    if [ "X${package}" = "X" ]; then
+        package=unknown
+        nopkg="true"
+    fi
+
+    case ${action} in
+    enable|disable)
+        ;;
+    *)
+        install_msg ${package} err $(_hhtpdmsg_nocfa ${package} ${caller})
+        return 10
+        ;;
+    esac
+
+    if [ "${nopkg}" = "true" ]; then
+        install_msg ${package} err $(_httpdmsg_nopkg "${caller} ${action}")
+        return 11
+    fi
+
+    return 0
+}
+
+# Return {new,old,unknown} when, respectively, the apache2 package uses
+# new / old packaging or it is not installed in the system.
+# ARGS: none
+#
+apache2_packaging ()
+{
+    if ! is_pkg_installed 'apache2'; then
+        echo 'unknown'
+	return
+    fi
+
+    local aversion=$(get_pkg_version 'apache2')
+    local amajor=$(version_major "${aversion}")
+    local aminor=$(version_minor "${aversion}")
+
+    local packaging="old"
+    case ${amajor} in
+    2)
+        if [ ${aminor} -ge 4 ]; then
+            packaging="new"
+        fi
+        ;;
+    *)
+        if [ ${amajor} -gt 2]; then
+            packaging="new"
+        fi
+        ;;
+    esac
+    echo ${packaging}
+}
+
+# Try to (en/dis)able an apache2 configuration snippet.
+# Return error if (en/dis)abling tried and failed; caller *must* check status.
+# ARGS:
+# $1={enable,disable} $2=package [$3=name_of_snippet_if_different_from_package]
+#
+try_chconf_apache2 ()
+{
+    local action=${1}
+    local package=${2}
+    local confname=${3}
+
+    local ret=0
+    _check_action_and_package ${action} ${package} "try_chconf_apache2" \
+        && ret=$? || ret=$?
+    if [ ${ret} -ne 0 ]; then
+        return ${ret}
+    fi
+
+    local confaction
+    if [ "${action}" = "enable" ]; then
+        confaction=enmod
+    else
+        confaction=dismod
+    fi
+
+    if [ "X${confname}" = "X" ]; then
+        confname=${package}
+    fi
+
+    case $(apache2_packaging) in
+    new)
+        # The apache2_invoke function also reloads the web server
+        # if it is running.
+
+        local ahelper=/usr/share/apache2/apache2-maintscript-helper
+
+        if [ -e $ahelper ] ; then
+            . $ahelper
+            apache2_invoke ${confaction} ${confname}.conf && ret=$? || ret=$?
+            if [ ${ret} -ne 0 ]; then
+                install_msg ${package} warning \
+                    "apache2_invoke returned an error;" \
+                    $(_httpdmsg_check ${package} apache2 ${action})
+            fi
+            return ${ret}
+        else
+            install_msg ${package} warning \
+                "apache2-maintscript-helper not found;" \
+                $(_httpdmsg_noact ${package} apache2 ${action})
+            return 1
+        fi
+        ;;
+    old)
+        # The apache2 init script uses apache2ctl configtest internally
+        # and also checks that the server is indeed running; thus there
+        # is no need to repeat these tests here.
+
+        invoke-rc.d apache2 reload && ret=$? || ret=$?
+        if [ ${ret} -ne 0 ]; then
+            install_msg ${package} warning \
+                "invoke-rc.d apache2 returned an error;" \
+                $(_httpdmsg_check ${package} apache2 ${action})
+        fi
+        return ${ret}
+        ;;
+    *)  # can only be unknown in which case apache2 is not installed; return
+        ;;
+    esac
+}
+
+# Try to (en/dis)able a lighttpd configuration snippet.
+# Return error if (en/dis)abling tried and failed; caller *must* check status.
+# ARGS:
+# $1={enable,disable} $2=package [$3=name_of_snippet_if_different_from_package]
+#
+try_chconf_lighttpd ()
+{
+    local action=${1}
+    local package=${2}
+    local confname=${3}
+
+    local ret=0
+    _check_action_and_package ${action} ${package} "try_chconf_lighttpd" \
+        && ret=$? || ret=$?
+    if [ ${ret} -ne 0 ]; then
+        return ${ret}
+    fi
+
+    local confaction
+    if [ "${action}" = "enable" ]; then
+        confaction=lighty-enable-mod
+    else
+        confaction=lighty-disable-mod
+    fi
+
+    if ! is_pkg_installed 'lighttpd'; then
+        return 0
+    fi
+
+    local confname=${package}
+
+    if [ "X${2}" != "X" ]; then
+        confname=${2}
+    fi
+
+    # lighty-xxx-mod will return 2 if no action is needed; workaround this.
+
+    if is_exec ${confaction}; then
+        ${confaction} ${confname} && ret=$? || ret=$?
+        if [ $ret -eq 1 ]; then
+            install_msg ${package} warning \
+                "${confaction} returned an error;" \
+                $(_httpdmsg_noact ${package} lighttpd ${action})
+            return 1
+        fi
+    else
+        install_msg ${package} warning \
+            "${confaction} not found;" \
+            $(_httpdmsg_noact ${package} lighttpd ${action})
+        return 2
+    fi
+
+    # Try to reload the web server configuration.
+
+    invoke-rc.d lighttpd reload && ret=$? || ret=$?
+    if [ ${ret} -ne 0 ]; then
+        install_msg ${package} warning \
+            "invoke-rc.d lighttpd returned an error;" \
+            $(_httpdmsg_check ${package} lighttpd ${action})
+    fi
+    return ${ret}
+}
+
diff --git a/debian/scripts/info.sh b/debian/scripts/info.sh
new file mode 100644
index 0000000..973d44d
--- /dev/null
+++ b/debian/scripts/info.sh
@@ -0,0 +1,84 @@
+# Information retrieval/display functions for Debian maintainer scripts.
+# Copyright (C) 2012 Georgios M. Zarkadas <gz@member.fsf.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public
+# License along with this program; if not, write to the Free
+# Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+# MA  02111-1307  USA.
+#
+# This file is intended to be sourced by maintainer scripts.
+
+
+# Return success if package is installed. 
+#
+is_pkg_installed ()
+{
+    LC_ALL=C dpkg --status ${1} 2>/dev/null \
+        | grep --quiet '^Status: install ok installed' 2>/dev/null
+    return $?
+}
+
+# Return the package version.
+#
+get_pkg_version ()
+{
+    echo $(LC_ALL=C dpkg --status ${1} 2>/dev/null \
+        | grep '^Version:' 2>/dev/null \
+        | cut --fields=2 --delimiter=' ' 2>/dev/null)
+}
+
+# Return the {major,minor,tail} part of version. Assume version has the form:
+#   major.minor.tail
+# The || true handles missing/ill-formed argument cases.
+
+version_major ()
+{
+    expr "${1}" \: '\([^.]\+\)' 2>/dev/null || true
+}
+
+version_minor ()
+{
+    expr "${1}" \: '[^.]\+\.\([^.]\+\)' 2>/dev/null || true
+}
+
+version_tail ()
+{
+    expr "${1}" \: '[^.]\+\.[^.]\+\.\([^.]\+\)' 2>/dev/null || true
+}
+
+# Display and record to syslog (if logger is available) an error message.
+#
+install_msg ()
+{
+    local package=${1}
+    local priority=${2}
+
+    # Remove package and priority from ARGV; then join all args to message.
+
+    shift; shift
+
+    local message="${package}:"
+    local arg
+
+    for arg; do
+        message="${message} ${arg}"
+    done
+
+    # Output to stanard error and to syslog, if logger is available.
+
+    >&2 echo "${message}"
+    if is_exec logger; then
+        logger -p syslog.${priority} -t "${package}" -- "${message}" || true
+    fi
+}
+