#!/bin/bash
#
# Copyright (C) 2008 Massimo Del Fedele <max@veneto.com>
#
#   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.
#
# Based on previous works of following authors :
#
# Copyright (C) 2001-2002 Sebastiano Vigna <vigna@acm.org>
# Modified by Michael Goffioul <goffioul@imec.be>
# Modified by Arnold Moene <a.f.moene@eduphys.xs4all.nl>
# Additional fixes by Kevin Ivory <Ivory@SerNet.de>
# Derived from fax4CUPS 1.22, a fax backend for CUPS, to use X app to 
# pick up fax info by Glenn Burkhardt <gbburkhardt@verizon.net>

export PATH=$PATH:/usr/local/bin
prefix=/usr
exec_prefix=${prefix}
bindir=${exec_prefix}/bin
PDFGUI=$bindir/maxpdf_frontend

# Called with no arguments, we list the provided maxpdf backend 
# (serial devices are irrelevant here).
if [ $# -eq 0 ]; then
    which $PDFGUI >& /dev/null
    if [ $? != 0 ]; then
	echo "ERROR: can't find MaxPdf program $i" 1>&2
	exit 1; 
    fi
    echo "direct maxpdf:/local \"Unknown\" \"MaxPdf printer\""
    exit 0
fi

# Check that 'sudo' can be executed by whatever account CUPS uses to run
SM=`sudo -l`
if [ $? != 0 ]; then
    UIDMSG=`id`
    echo "ERROR: CUPS runs under '$UIDMSG'; can't run 'sudo': $SM" 1>&2
    exit 1
fi

# Get the user that owns the job
USER=$2

echo 1>&2 # Apparently the first character emitted is somehow "eaten" by the reader

# Check for correct display variable to use.  Most systems use :0.0; 
unset XAUTHORITY
disp=`sudo -H -u $USER xauth list :0`
if [ "$disp" = "" ] ; then
    disp=`sudo -H -u $USER xauth list | awk 'match($0, /(unix)(:[0-9][0-9]*)/, dn) { print dn[2]; exit }'`
    # check result
    export DISPLAY=$disp
else
    export DISPLAY=:0
fi

# If we find six arguments, the last one is the pdf name; otherwise,
# we're reading the fax data from stdin.
# we copy the file in tmp directory, so everybody can access it
PDFNAME=$(mktemp </dev/null /tmp/pdf.XXXXXX) || (echo "ERROR: Failed to create temporary file" 1>&2; exit 1)
if [ $# -eq 6 ]; then
	# copy over file from spool directory
	cp $6 $PDFNAME
else
	# copy from stdin
	cat > $PDFNAME
fi

# changes owner of temporary file so we can remove it from gui app
# this is needed because this shell can terminate before gui app
# finishes processing the file, so we can't remove it from here
# This is the only sudo root access to the system, it can be safely
# removed, but then spool files will stay in tmp directory until reboot
chmod ugo+rw $PDFNAME
sudo chown $USER:$USER $PDFNAME

# Checks for the gui part of driver
which $PDFGUI >& /dev/null
if [ $? != 0 ]; then
 	echo "ERROR: can't find '$PDFGUI' program; check execution search path" 1>&2
	exit 1
fi

# Use sudo to make sure that job is owned by the user that wants to "print",
# not root. This is needed so that the owner of the job can remove it if 
# needed.
# Some systems have /etc/sudoers configured with "Default env_reset", which
# causes the DISPLAY environment variable to be thrown away.  So we tell
# 'sudo' to invoke a shell, and make sure the DISPLAY variable is set.
# We use -b sudo option to run the command in background and detached from
# this shell, so it can stay opened for more print cycles.
# Doing so, we can't check the gui return value, so we assume it's ok
# We add the PRINTER parameted to allow gui part of application to control
# the print job, and to remove when it's completed; I didn't find any other
# reliable way to empty printer queue AND leave gui part opened
#                                      CUPS ARGUMENTS :  job user  title copies  options  faxfile  printer
sudo -b -H -u $USER /bin/sh -c "DISPLAY=$DISPLAY $PDFGUI  $1  $2   \"$3\"   $4    \"$5\" $PDFNAME $PRINTER"

# exit signaling all ok to cups subsystem
exit 0