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https://github.com/fsquillace/junest.git
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98 lines
2.8 KiB
Bash
Executable file
98 lines
2.8 KiB
Bash
Executable file
#!/bin/bash
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#
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# This script is the simplified and portable version of arch-chroot
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# (https://wiki.archlinux.org/index.php/Change_root#Using_arch-chroot)
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#
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set -e
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JUNEST_BASE="$(readlink -f $(dirname $(readlink -f "$0"))/..)"
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source "${JUNEST_BASE}/lib/utils.sh"
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################################ MAIN FUNCTIONS ###########################
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chroot_add_mount() {
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mount "$@" && CHROOT_ACTIVE_MOUNTS=("$2" "${CHROOT_ACTIVE_MOUNTS[@]}")
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}
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chroot_maybe_add_mount() {
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local cond=$1; shift
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if eval "$cond"; then
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chroot_add_mount "$@"
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fi
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}
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chroot_setup() {
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CHROOT_ACTIVE_MOUNTS=()
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[[ $(trap -p EXIT) ]] && die '(BUG): attempting to overwrite existing EXIT trap'
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trap 'chroot_teardown' EXIT
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chroot_maybe_add_mount "! mountpoint -q '$1'" "$1" "$1" --bind &&
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chroot_add_mount proc "$1/proc" -t proc -o nosuid,noexec,nodev &&
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chroot_add_mount sys "$1/sys" -t sysfs -o nosuid,noexec,nodev,ro &&
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chroot_add_mount udev "$1/dev" -t devtmpfs -o mode=0755,nosuid &&
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chroot_add_mount devpts "$1/dev/pts" -t devpts -o mode=0620,gid=5,nosuid,noexec &&
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chroot_add_mount shm "$1/dev/shm" -t tmpfs -o mode=1777,nosuid,nodev &&
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chroot_add_mount run "$1/run" -t tmpfs -o nosuid,nodev,mode=0755 &&
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chroot_add_mount tmp "$1/tmp" -t tmpfs -o mode=1777,atime,nodev,nosuid &&
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mkdir -p "$1/$HOME" &&
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chroot_add_mount $HOME "$1/$HOME" --bind
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mkdir -p "$1/run/lock"
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}
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chroot_teardown() {
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umount "${CHROOT_ACTIVE_MOUNTS[@]}"
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unset CHROOT_ACTIVE_MOUNTS
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}
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usage() {
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cat <<EOF
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usage: ${0##*/} chroot-dir [command]
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-h Print this help message
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If 'command' is unspecified, ${0##*/} will launch /bin/sh.
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EOF
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}
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chroot_add_resolv_conf() {
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local chrootdir=$1 resolv_conf=$1/etc/resolv.conf
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# Handle resolv.conf as a symlink to somewhere else.
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if [[ -L $chrootdir/etc/resolv.conf ]]; then
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# readlink(1) should always give us *something* since we know at this point
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# it's a symlink. For simplicity, ignore the case of nested symlinks.
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resolv_conf=$(readlink "$chrootdir/etc/resolv.conf")
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if [[ $resolv_conf = /* ]]; then
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resolv_conf=$chrootdir$resolv_conf
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else
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resolv_conf=$chrootdir/etc/$resolv_conf
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fi
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# ensure file exists to bind mount over
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if [[ ! -f $resolv_conf ]]; then
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install -Dm644 /dev/null "$resolv_conf" || return 1
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fi
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fi
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chroot_add_mount /etc/resolv.conf "$resolv_conf" --bind
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}
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if [[ -z $1 || $1 == -h || $1 == --help ]]; then
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usage
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exit $(( $# ? 0 : 1 ))
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fi
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(( EUID == 0 )) || die 'This script must be run with root privileges'
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chrootdir=$1
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shift
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[[ -d $chrootdir ]] || die "Can't create chroot on non-directory $chrootdir"
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chroot_setup "$chrootdir" || die "failed to setup chroot $chrootdir"
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chroot_add_resolv_conf "$chrootdir" || die "failed to setup resolv.conf"
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SHELL="/bin/sh" chroot "$chrootdir" "$@"
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