#!/bin/sh
# chgroup v1.2  (c) 6.9.2000 by Andreas Ley  (u) 12.4.2010
# Add a group or replace an existing or all groups in /etc/group

group="/etc/group"

usage()
{
	echo "Usage: `basename $0` [options] input-mode" >&2
	echo "or:    `basename $0` [options] [option value] [...] group [...]" >&2
	echo "Options:" >&2
	echo "-A        Add group" >&2
	echo "-R        Remove group" >&2
	echo "-N        Rebuild group file (will always keep groups with gid < 2000 and" >&2
	echo "          replace all groups with gid >= 2000)" >&2
	echo "-F group  Use alternate group file" >&2
	echo "Valid input modes:" >&2
	echo "-E entry  group(4) entry" >&2
	echo "-G        Group mode, read group(4) lines from stdin" >&2
	echo "Currently there are no valid option value pairs... will be implemented on need" >&2
	echo "Will always keep groups with gid < 2000 and replace all groups with gid >= 2000" >&2
	exit 1
}

echo "\n" | grep "n" >/dev/null && e="-e"

set -- `getopt ARNF:E:Ghx $*` || usage

trace=false
while :; do
	case $1 in
		-h)	sed '1d;s/^# *//;/^$/q' $0; usage;;
		-x)	set -x; trace=true; shift;;
		-A)	test -n "${remove}${rebuild}" && usage; add=true; shift;;
		-R)	test -n "${add}${rebuild}" && usage; remove=true; shift;;
		-N)	test -n "${add}${remove}" && usage; rebuild=true; shift;;
		-F)	group="$2"; shift 2;;
		-E)	test -n "${stdin}" && usage; entries="${entries}${entries:+\n}$2"; shift 2;;
		-G)	test -n "${entries}" && usage; stdin=true; shift;;
		--)	shift; break;;
	esac
done

test -z "${add}${remove}${rebuild}" \
	-o -n "${add}${rebuild}" -a -z "${entries}${stdin}" \
	-o $# -eq 0 -a -z "${entries}${stdin}" \
	-o $# -ne 0 -a -n "${rebuild}${entries}${stdin}" && usage

tmp="`/usr/machine/bin/mktemp -c -d \`dirname ${group}\` -p .\`basename ${group}\`.`"

# FIXME: Debug only, w/ race conditon - remove after test!
cp -p ${group} /tmp/group.`date '+%Y-%m-%dT%H:%M:%S'`

if test -n "${remove}"; then
	if test -n "${entries}"; then
		echo ${e} "${entries}" | cut -d: -f1
	elif test -n "${stdin}"; then
		cut -d: -f1
	else
		echo "$@"
	fi | while read name; do
		if grep -E "^${name}:[^:]*:([2-9][0-9]{3,}|[0-9]{5,})" ${group} >/dev/null; then
			grep -v -E "^${name}:[^:]*:([2-9][0-9]{3,}|[0-9]{5,})" ${group} >${tmp} && \
				cat ${tmp} >${group}
		fi
	done
elif test -n "${rebuild}"; then
	grep -v -E "^(\+|[^:]*:[^:]*:([2-9][0-9]{3,}|[0-9]{5,})):" ${group} >${tmp} && \
		if test -n "${entries}"; then
			echo ${e} "${entries}"
		else
			cat
		fi | \
		grep -E "^[^:]*:[^:]*:([2-9][0-9]{3,}|[0-9]{5,})" >>${tmp} && \
		cat ${tmp} >${group}
else
	nis="`/usr/machine/bin/mktemp -c -p .\`basename $0\`.`"
	if test -n "${entries}"; then
		echo ${e} "${entries}"
	elif test -n "${stdin}"; then
		cat
	fi | while read entry; do
		gid="`echo ${entry} | cut -d: -f3`"
		if test ${gid:-0} -ge 2000; then
			name="`echo ${entry} | cut -d: -f1`"
			# We have to separate NIS entries, since Linux NIS
			# doesn't accept normal entries behind NIS entries
			grep "^+" ${group} >${nis}
			if grep -E "^${name}:[^:]*:([2-9][0-9]{3,}|[0-9]{5,})" ${group} >/dev/null; then
				grep -v -E "^(\+|${name}:[^:]*:([2-9][0-9]{3,}|[0-9]{5,}))" ${group} >${tmp} && \
					echo "${entry}" >>${tmp} && \
					cat ${nis} >>${tmp} && \
					cat ${tmp} >${group}
			else
				if test -s ${nis}; then
					grep -v "^+" ${group} >${tmp} && \
					echo "${entry}" >>${tmp} && \
					cat ${nis} >>${tmp} && \
					cat ${tmp} >${group}
				else
					echo "${entry}" >>${group}
				fi
			fi
		fi
	done
	rm -f ${nis}
fi

rm -f ${tmp}

exit 0