#!/bin/bash
# Original...
# Copyright (c) 2000,2004 Matthias S. Benkmann <article AT winterdrache DOT de>
# You may do everything with this code except misrepresent its origin.
# PROVIDED `AS IS' WITH ABSOLUTELY NO WARRANTY OF ANY KIND!

# Copyright (C) 2014 Steve Youngs <steve@steveyoungs.com>
#  Rewrite, make it a lot more robost and handle most (all?) 
#  possibilities of chown'ing. --SY.

DAISY_CHAIN=""

for p in $(type -ap chown) ; do
    if [ ! $p -ef $0 ]; then
	DAISY_CHAIN=$p
	break
    fi
done

if [ ! -n "$DAISY_CHAIN" ]; then
    echo 1>&2 '***' Cannot find real ${0##*/} command 
    exit 1
fi

if [ $UID == 0 ]; then
    echo 1>&2 '***' $(dirname $0) should not be in root\'s \$PATH
    echo 1>&2 '***' call '"'$DAISY_CHAIN $@'"' directly.
    exit 1
fi

# An ordinary user cannot change the UID of a file if that UID is
# not their own, but chown can also be used to change the GID of a
# file as well so it is feasible that an ordinary user could use
# chown successfully.

# preseve the command line as we're gonna mess with it.
cmdline="$@"
# strip off the options so that $1 becomes the UID:GID arg
while [ -n "$1" ]; do
    case "$1" in
	(-*) shift ;;
	(*) break ;;
    esac
done

# Split USER:GROUP or USER.GROUP into USER and GROUP
usrgrp="$1"
usr=${usrgrp/[.:]*/}
grp=${usrgrp/*[.:]/}

report=0

# Catch the case where USER is somebody else.
if [ -n "$usr" ]; then
    printf '%d' $usr &>/dev/null
    if [ $? -eq 0 ]; then
	if [ $usr -ne $(id -u) ]; then
	    report=1
	fi
    else
	if [ "$usr" != "$(id -un)" ]; then
	    report=1
	fi
    fi
fi

# Catch the case where GROUP isn't in our groups.
if [ -n "$grp" -a $report -eq 0 ]; then
    GRP_CHAIN=""
    printf '%d' $grp &>/dev/null
    if [ $? -eq 0 ]; then
	GRP_LIST=$(id -G)
    else
	GRP_LIST=$(id -Gn)
    fi
    for g in ${GRP_LIST}; do
	if [ "$grp" == "$g" ]; then
	    GRP_CHAIN=$g
	    break
	fi
    done

    if [ -z "$GRP_CHAIN" ]; then
	report=1
    fi
fi

if [ $report -eq 1 ]; then
    echo 1>&2 '***' chown ${cmdline}
else
    exec $DAISY_CHAIN ${cmdline} || exit $?
fi

exit 0

# Local variables:
# sh-basic-offset: 4
# End: