#!/bin/sh -e

##########################################################################
#   Script description:
#       
#   Arguments:
#       
#   Returns:
#       
#   History:
#   Date        Name        Modification
#   2017-05-13  root        Begin
##########################################################################

usage()
{
    cat << EOM

Usage: $0 dir ['cmd']

Default cmd is /bin/sh.

Examples:
    $0 chroot-centos-6
    $0 chroot-centos-6 /pbulk/bin/bulkbuild

EOM
    exit 1
}


##########################################################################
#   Main
##########################################################################

case $# in
1)
    cmd=/bin/sh
    ;;
2)
    cmd="$2"
    ;;
*)
    usage
esac

dir=$1

if [ ! -d $dir ]; then
    printf "${dir}: No such directory.\n"
    exit 1
fi

umask 022

case `uname` in
Linux)
    mount_cmd='mount --bind'
    ;;
NetBSD)
    mount_cmd=mount_null
    ;;
FreeBSD)
    mount_cmd=mount_nullfs
    ;;
*)
    printf "`uname` is not yes supported.\n"
    exit 1
esac

mkdir -p $dir/proc $dir/dev
if [ 0"$(ls $dir/proc)" != 0 ] || [ 0"$(ls $dir/proc)" != 0 ]; then
    printf "$dir/proc and $dir/dev must be empty for null-mounting.\n"
    exit 1
fi
if [ -e /proc ]; then
    $mount_cmd /proc $dir/proc
fi
$mount_cmd /dev $dir/dev
if [ `uname` = NetBSD ]; then
    mkdir -p $dir/kern
    if [ 0"$(ls $dir/kern)" != 0 ]; then
	printf "$dir/kern must be empty for null-mounting.\n"
	exit 1
    fi
    $mount_cmd /kern $dir/kern
fi
cp -fp /etc/resolv.conf $dir/etc

PATH=/usr/bin:/usr/sbin:/bin:/sbin:/opt/pkg/bin:/opt/pkg/sbin:/usr/pkg/bin:/usr/pkg/sbin
export PATH

# Make sure umounts happen
set +e

chroot $dir $cmd

# Unmount in proper order
if [ `uname` = NetBSD ]; then
    umount $dir/kern
fi
umount $dir/dev
if [ -e /proc ]; then
    umount $dir/proc
fi