.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 ${UNSHARE} ]] ; then
   7                 mount_args=
   8                 if type -P unshare >&/dev/null ; then
   9                         test_arg() { unshare "$@" -- true >&/dev/null && uargs+=( "$@" ) || :; }
  10                         uargs=( -m )
  11                         test_arg -u
  12                         test_arg -i
  13                         test_arg -p -f --mount-proc
  14                         test_arg --propagation=private
  15                         UNSHARE=true exec unshare "${uargs[@]}" -- "$0" "$@"
  16                 fi
  17         else
  18                 mount_args='-n'
  19         fi
  20         unset UNSHARE
  21 }
  22
  23 is_mounted() {
  24         local dst=$1
  25         grep -sq "${dst}" /proc/mounts
  26 }
  27
  28 maybe_mount() {
  29         local src=/$1 dst=${chroot}/${2:-$1}
  30         [[ -d ${src} ]] || return 0
  31         if ! mkdir -p "${dst}" ; then
  32                 [[ -w ${chroot} ]] && exit 1 || return 0
  33         fi
  34         is_mounted "${dst}" || mount ${mount_args} --bind "${src}" "${dst}"
  35 }
  36
  37 get_type() {
  38         case $(file "$1") in
  39         *x86-64*)             echo x86_64;;
  40         *"Intel 80386"*)      echo i386;;
  41         *32-bit*PowerPC*MSB*) echo ppc;;
  42         *64-bit*PowerPC*MSB*) echo ppc64;;
  43         *32-bit*PowerPC*LSB*) echo ppcle;;
  44         *64-bit*PowerPC*LSB*) echo ppc64le;;
  45         *32-bit*S/390*)       echo s390;;
  46         *64-bit*S/390*)       echo s390x;;
  47         *64-bit*MIPS*)        echo mips64;;
  48         *32-bit*MIPS*N32*)    echo mips64;;
  49         *32-bit*MIPS*)        echo mips;;
  50         *32-bit*PA-RISC*)     echo parisc;;
  51         *64-bit*PA-RISC*)     echo parisc64;;
  52         *32-bit*SPARC*)       echo sparc;;
  53         *64-bit*SPARC*)       echo sparc64;;
  54         esac
  55 }
  56
  57 init_chroot() {
  58         [[ -w . ]] || return 0
  59
  60         if [[ ! -L etc/mtab ]] ; then
  61                 ln -sfT /proc/mounts etc/mtab
  62         fi
  63         local f dst
  64         local etc=(
  65                 hosts
  66                 locale.gen
  67                 localtime
  68                 resolv.conf
  69         )
  70         local home=(
  71                 .inputrc
  72                 .gdbinit
  73                 .gitconfig
  74                 .nanorc
  75         )
  76         for f in \
  77                 $(printf 'etc/%s ' "${etc[@]}") \
  78         ; do
  79                 if [[ -e /${f} ]] ; then
  80                         cp "/${f}" "${f}"
  81                 fi
  82         done
  83         for f in "${home[@]}" ; do
  84                 df="root/${f}"
  85                 f="${HOME}/${f}"
  86                 if [[ -e ${f} ]] ; then
  87                         cp "${f}" "${df}"
  88                 fi
  89         done
  90
  91         if [[ ! -d root/.git ]] ; then
  92                 f="${HOME}/.profile.d/aliases.sh"
  93                 if [[ -e ${f} ]] ; then
  94                         cat "${f}" > root/.bash_profile
  95                 fi
  96         fi
  97 }
  98
  99 usage() {
 100         cat <<-EOF
 101         Usage: ${0##*/} [options] [program to run]
 102
 103         Sets up common mount points and then chroots in and runs a program.
 104         If no program is specified, then launch a login shell.
 105
 106         Options:
 107           -u          Unmount all paths in the chroot
 108           -m <path>   Add path to mount list
 109           -d <dir>    Use <dir> as chroot (defaults to ${0%/*})
 110           -h          This help screen
 111         EOF
 112         exit
 113 }
 114
 115 main() {
 116         bootstrap "$@"
 117
 118         local mounts=(
 119                 proc sys tmp dev dev/shm run
 120                 usr/portage usr/portage/distfiles
 121                 var/db/repos/gentoo var/cache/distfiles
 122                 usr/local/src
 123         )
 124
 125         local chroot=${0%/*}
 126         case ${chroot} in
 127         .) chroot=${PWD} ;;
 128         ./*) chroot=${PWD}/${chroot#./} ;;
 129         esac
 130
 131         local cmd
 132         while [[ -n $1 ]] ; do
 133                 case $1 in
 134                 -u) cmd='umount' ;;
 135                 -m) mounts+=( "$2" ); shift ;;
 136                 -d) chroot=$(realpath "$2"); shift ;;
 137                 --help|-h) usage ;;
 138                 -*) echo "${0##*/}: unknown option $1"; exit 1 ;;
 139                 *)  break ;;
 140                 esac
 141                 shift
 142         done
 143         cd "${chroot}"
 144
 145         case ${cmd} in
 146         umount) exec "${0%/*}/umount-tree" -y "${chroot}" ;;
 147         esac
 148
 149         local m
 150         for m in "${mounts[@]}" ; do
 151                 maybe_mount "${m}"
 152         done
 153         # Handle special mounts that we don't want to just bind mount.
 154         if ! is_mounted "${chroot}/dev/pts" ; then
 155                 # Option order matters: on older kernels that don't recognize newinstance,
 156                 # parsing stops as soon as it hits that.
 157                 mount -t devpts devpts "${chroot}/dev/pts" \
 158                         -o nosuid,noexec,mode=0620,gid=5,ptmxmode=0666,newinstance
 159         fi
 160
 161         init_chroot
 162
 163         local setarch
 164         if type -P setarch &>/dev/null ; then
 165                 local bin_dst=$(get_type bin/bash)
 166                 if [[ -n ${bin_dst} ]] ; then
 167                         setarch="setarch ${bin_dst}"
 168                 fi
 169         fi
 170
 171         # Doubtful these settings we want to leak into the chroot.
 172         unset ROOT PORTAGE_CONFIGROOT LD_LIBRARY_PATH
 173         unset LS_COLORS # format changes over time
 174         [[ $# -eq 0 ]] && set -- env HOME=/root /bin/bash -l
 175         exec \
 176                 ${setarch} \
 177                 chroot "${chroot}" \
 178                 "$@"
 179 }
 180
 181 main "$@"