.bin/custom-chroot

   1 #!/bin/bash -e
   2
   3 bootstrap() {
   4         [[ $(id -u) -eq 0 ]] || exec sudo env -uUNSHARE HOME="$HOME" "$0" "$@"
   5
   6         if [[ -z ${UNSHARE} ]] ; then
   7                 mount_args=
   8                 if type -P unshare >&/dev/null ; then
   9                         uargs=( -m )
  10                         unshare -u -- true >&/dev/null && uargs+=( -u )
  11                         unshare -p -- true >&/dev/null && uargs+=( -p -f --mount-proc )
  12                         UNSHARE=true exec unshare "${uargs[@]}" -- "$0" "$@"
  13                 fi
  14         else
  15                 mount_args='-n'
  16         fi
  17         unset UNSHARE
  18 }
  19
  20 maybe_mount() {
  21         local src=/$1 dst=${chroot}/${2:-$1}
  22         [[ -d ${src} ]] || return 0
  23         if ! mkdir -p "${dst}" ; then
  24                 [[ -w ${chroot} ]] && exit 1 || return 0
  25         fi
  26         grep -sq "${dst}" /proc/mounts || mount ${mount_args} --bind "${src}" "${dst}"
  27 }
  28
  29 get_type() {
  30         case $(file "$1") in
  31         *x86-64*)         echo x86_64;;
  32         *"Intel 80386"*)  echo i386;;
  33         *32-bit*PowerPC*) echo ppc;;
  34         *64-bit*PowerPC*) echo ppc64;;
  35         *32-bit*S/390*)   echo s390;;
  36         *64-bit*S/390*)   echo s390x;;
  37         esac
  38 }
  39
  40 init_chroot() {
  41         [[ -w . ]] || return 0
  42
  43         if [[ ! -L etc/mtab ]] ; then
  44                 ln -sfT /proc/mounts etc/mtab
  45         fi
  46         local f dst
  47         local etc=(
  48                 hosts
  49                 locale.gen
  50                 localtime
  51                 resolv.conf
  52         )
  53         local home=(
  54                 .inputrc
  55                 .gdbinit
  56                 .gitconfig
  57                 .nanorc
  58         )
  59         for f in \
  60                 $(printf 'etc/%s ' "${etc[@]}") \
  61         ; do
  62                 if [[ -e /${f} ]] ; then
  63                         cp "/${f}" "${f}"
  64                 fi
  65         done
  66         for f in "${home[@]}" ; do
  67                 df="root/${f}"
  68                 f="${HOME}/${f}"
  69                 if [[ -e ${f} ]] ; then
  70                         cp "${f}" "${df}"
  71                 fi
  72         done
  73
  74         f="${HOME}/.profile.d/aliases.sh"
  75         if [[ -e ${f} ]] ; then
  76                 cat "${f}" > root/.bash_profile
  77         fi
  78 }
  79
  80 usage() {
  81         cat <<-EOF
  82         Usage: ${0##*/} [options] [program to run]
  83
  84         Sets up common mount points and then chroots in and runs a program.
  85         If no program is specified, then launch a login shell.
  86
  87         Options:
  88           -u          Unmount all paths in the chroot
  89           -m <path>   Add path to mount list
  90           -d <dir>    Use <dir> as chroot (defaults to ${0%/*})
  91           -h          This help screen
  92         EOF
  93         exit
  94 }
  95
  96 main() {
  97         bootstrap "$@"
  98
  99         local mounts=( proc sys tmp dev dev/pts dev/shm usr/portage usr/portage/distfiles usr/local/src )
 100
 101         local chroot=${0%/*}
 102         case ${chroot} in
 103         .) chroot=${PWD} ;;
 104         ./*) chroot=${PWD}/${chroot#./} ;;
 105         esac
 106
 107         local cmd
 108         while [[ -n $1 ]] ; do
 109                 case $1 in
 110                 -u) cmd='umount' ;;
 111                 -m) mounts+=( "$2" ); shift ;;
 112                 -d) chroot=$(realpath "$2"); shift ;;
 113                 -h) usage ;;
 114                 -*) echo "${0##*/}: unknown option $1"; exit 1 ;;
 115                 *)  break ;;
 116                 esac
 117                 shift
 118         done
 119         cd "${chroot}"
 120
 121         case ${cmd} in
 122         umount) exec "${0%/*}/umount-tree" -y "${chroot}" ;;
 123         esac
 124
 125         local m
 126         for m in "${mounts[@]}" ; do
 127                 maybe_mount ${m}
 128         done
 129
 130         init_chroot
 131
 132         local setarch
 133         if type -P setarch &>/dev/null ; then
 134                 local bin_dst=$(get_type bin/bash)
 135                 if [[ -n ${bin_dst} ]] ; then
 136                         setarch="setarch ${bin_dst}"
 137                 fi
 138         fi
 139
 140         # Doubtful these settings we want to leak into the chroot.
 141         unset ROOT PORTAGE_CONFIGROOT LD_LIBRARY_PATH
 142         unset LS_COLORS # format changes over time
 143         [[ $# -eq 0 ]] && set -- env HOME=/root /bin/bash -l
 144         exec \
 145                 ${setarch} \
 146                 chroot "${chroot}" \
 147                 "$@"
 148 }
 149
 150 main "$@"