#!/bin/sh
#
# Author: Todd Stansell <todd@stansell.org>
# $Id: cron-edit,v 1.10 2005-06-15 14:18:18-07 todd Exp $
#
# cron-edit
#
#    add/remove/monitor the crontab entry
#
# manages crontab entries by adding the following to crontab:
#
#    # BEGIN_cron-edit_<tag>
#    # Do not modify, managed by VCS
#    <crontab entries from $config here>
#    ...
#    # END_cron-edit_<tag>
#
# This is intended for use with VCS 1.3.0 and above as an Application
# type.   Here is an example Application Agent:
#
#    # hares -display cron_ora
#    ...
#    cron_ora  CleanProgram     global
#    cron_ora  MonitorProcesses global
#    cron_ora  MonitorProgram   global    /tools/custom/bin/cron-edit \
#		-u oracle -t ora -C
#    cron_ora  PidFiles         global
#    cron_ora  StartProgram     global    /tools/custom/bin/cron-edit \
#		-u oracle -t ora -a /oracle/.crontabs/cron_ora
#    cron_ora  StopProgram      global    /tools/custom/bin/cron-edit \
#		-u oracle -t ora -r
#    cron_ora  User             global
#

BASE=`basename $0`
tag=none
action=none
config=
verbose=
user=
success=0
fail=1

before=/tmp/$BASE$$-before
after=/tmp/$BASE$$-after

begin="# BEGIN_cron-edit"
mesg="# Do not modify the following entries.  They are managed by cron-edit."
end="# END_cron-edit"

USAGE="usage: $BASE [-h] [-v] [-t tag] [-u user] {-a file | -r | -c | -C}
    -h		help
    -v		verbose
    -t tag	tag to identify entry with (default: $tag)
    -u user	username for crontab (no default)
    -a file	update managed crontab entry with contents of \"file\"
    -r		remove entire managed crontab entry
    -c		check for entry and exit with 0 if present else 1
    -C		check for entry and exit with 1 if present else 0 (VCS)"

#
# update the cron entry with stuff in $after
#
# return codes:
#	0	crontab edit succeeded
#	1	crontab edit failed
#
update_cron(){
	[ "$verbose" ] && diff $before $after
	
	#
	# This check is because crontab -e doesn't like it when
	# you leave the edited crontab as an empty file, so we
	# have to explicitly remove the user's crontab entry.
	#
	if [ ! -s $after ] ; then
		#
		# if the new config is empty, then just remove it...
		#
		[ "$verbose" ] && echo executing crontab -r $user
		crontab -r $user 2>/dev/null
	else
		#
		# otherwise, replace the crontab with $after.
		#
		if [ "$user" ] ; then
			[ "$verbose" ] && echo "executing crontab -e $user"
			EDITOR="cp $after" VISUAL="cp $after" \
				crontab -e $user >/dev/null
		else
			[ "$verbose" ] && echo "executing crontab $after"
			crontab $after
		fi
	fi
}

#
# check to see that the $start line is in the crontab
# which assumes that the rest is there...
#
# return codes:
#	0	begin entry was found
#	1	begin entry was not found
#
check_entry() {
	#
	# Here we save a copy of the crontab as $before.
	# This is run before anything else and $before is
	# expected to exist to make any changes.
	#
	crontab -l $user >$before 2>/dev/null
	if [ ! -s $before ] ; then
		# no crontab entry, so it's not in there.
		return 1
	fi
	cat $before | grep "^$begin\$" >/dev/null 2>&1; status=$?
	return $status
}

#
# add appropriate cron-edit stuff for <tag>...
#
add_entry() {
	remove_entry
	if [ $? -eq $fail ] ; then
		return $fail
	fi
	cp $before $after
	echo "$begin" >>$after
	echo "$mesg" >>$after
	cat $config >>$after
	echo "$end" >>$after
	update_cron
}

#
# remove the cron-edit stuff for <tag>...
#
remove_entry() {
	if check_entry ; then
		#
		# check_entry succeeded, so there *must* be
		# a begin/end pair
		#
		cp $before $after
		ed $after >/dev/null <<-EOT
			/^$begin\$/,/^$end\$/d
			w
			q
		EOT
		update_cron
		if check_entry ; then
		    return $fail
		fi
	fi
	return $success
}

#
# cleanup left over files...
#
cleanup() {
	for file in $before $after ; do
		[ -f $file ] && rm $file
	done
}

#############################################
#	  BEGIN MAIN PROGRAM
#############################################

#
# lets try to clean things up if we die
#
trap cleanup 0 1 2 3 5 15

while getopts a:u:t:rcChv c; do
	case $c in
		a)	action=add; config=$OPTARG ;;
		u)	user=$OPTARG ;;
		t)	tag=$OPTARG ;;
		r)	action=remove ;;
		c)	action=check; success=0; fail=1 ;;
		C)	action=check; success=1; fail=0 ;;
		v)	verbose=true ;;
		h)	echo "$USAGE" ; exit 0 ;;
		*)	echo "$USAGE" >&2 ; exit 64 ;;
	esac
done
shift `expr $OPTIND - 1`

#
# make sure we're root if we specify a user.
#
if [ "$user" ] ; then
	if /bin/id | grep -v '^uid=0(' >/dev/null ; then
		echo "$BASE: must be run as root" >&2
		exit 64
	fi
fi
#
# SunOS 5.5 and 5.5.1 is broken. Needs to be 5.6 or above.
# Crontab doesn't behave as it should.  It appears that it
# doesn't pass standard-in to the editor...
#
case `/bin/uname -r` in
	5.5|5.5.1)	echo "SunOS `uname -r` crontab is broken."
		echo "This will only work on 5.6 or above."
		exit 64
		;;
esac

#
# get full path to config, if no leading slash
#
if echo "$config" | grep "^[^/]" >/dev/null ; then
	#
	# expr returns 0, then no leading /
	#
	conf=`basename $config`
	dir=`dirname $config`
	dir=`cd $dir ; /bin/pwd`
	config=$dir/$conf
fi
	
#
# update variables
#
begin="${begin}_$tag"
mesg="$mesg
# Entries from: $config"
end="${end}_$tag"

case $action in
	add)	if [ ! -f $config ] ; then
			exit 1
		fi
		add_entry
		exit $?
		;;

	remove)	remove_entry
		exit $?
		;;

	check)
		if check_entry ; then
			exit $success
		else
			exit $fail
		fi
		;;
esac