le-proinfodata: Fix session-setup-script option on lightdm

Signed-off-by: Diego Giovane Pasqualin <dpasqualin@c3sl.ufpr.br>

le-proinfodata/package/DEBIAN/control

 Package: le-proinfodata
-Version: 1.2.40
+Version: 1.2.42
 Maintainer: <proinfodata@c3sl.ufpr.br>
 Architecture: i386
 Section: main

le-proinfodata/package/DEBIAN/postinst

 #!/bin/bash
-# Copyright (C) 2004-2010 Centro de Computacao Cientifica e Software Livre
+# Copyright (C) 2004-2014 Centro de Computacao Cientifica e Software Livre
 # Departamento de Informatica - Universidade Federal do Parana - C3SL/UFPR
 #
 # This file is part of proinfodata
@@ -26,6 +26,28 @@ BACKUP_DIR="/opt/seed_mec_backup"
 LBFILE="/etc/le-proinfodata/le.zone.bz2"
 MULTISEAT_DIR="/etc/userful/scripts/PostLogin"
 
+# Set option on lightdm.conf. If the option $1 already exists, make sure it
+# has the value $2. If it doesn't exist, add it.
+function setLightdmOption() {
+    local option=$1
+    local value=$2
+    if ! grep -q "$option" /etc/lightdm/lightdm.conf; then
+        sed -i "/\[SeatDefaults\]/ a ${option}=${value}" \
+            /etc/lightdm/lightdm.conf
+    else
+        sed -i  "/${option}/ s#=.*#=${value}#" \
+            /etc/lightdm/lightdm.conf
+    fi
+}
+
+# Check whether file $1 was already diverted.
+# Return true if it was and false otherwise.
+function alreadyDiverted() {
+    file="$1"
+    dpkg-divert --listpackage $file | grep -q le-proinfodata
+    return $?
+}
+
 # Descompressing the local base
 [[ -f $LBFILE ]] && bunzip2 -f $LBFILE
 
@@ -54,13 +76,7 @@ fi
 # Set lightdm to open the le-proinfodata configuration script when user
 # session starts
 if [[ ! -d $MULTISEAT_DIR ]]; then
-    if ! grep -q "session.*exec_dialog.sh" "/etc/lightdm/lightdm.conf"; then
-        sed -i '/\[SeatDefaults\]/ a\session-setup-script=/usr/local/bin/exec_dialog.sh' \
-            /etc/lightdm/lightdm.conf
-    fi
-else
-    sed -i '\,session-setup-script=/usr/local/bin/exec_dialog.sh,d' \
-        /etc/lightdm/lightdm.conf
+    setLightdmOption "session-setup-script" "/usr/local/bin/exec_dialog.sh"
 fi
 
 # We will no longer need this files, but as the postrm would only remove the
@@ -70,9 +86,7 @@ DIVERTS="
  /etc/init/tty1.conf \
 "
 for file in $DIVERTS; do
-    # Why the heck dpkg-divert doesn't return 'false' if the pattern doesn't
-    # match on the --list option?
-    if [ -n "$(dpkg-divert --list $file)" ]; then
+    if alreadyDiverted $file; then
         dpkg-divert --package le-proinfodata --remove --rename \
                     --divert ${file}{.real,}
     fi