58ff428757
As described in2be79c6("run the chroot in a new PID namespace"), child processes can hang around and keep various files open. This may prevent filesystems from being unmounted (as they are still in-use). When adding unshare mode, I did not quite understand this distinction (and I wasn't testing with e.g. gnupg) so I didn't catch this. Fix this by always using unshare to create a second pid namespace for "worker" processes. This ensures that all children are dead when we start unmounting things. As the top-level unshare is no longer always necessary, convert the unshare variable to a binary value. Fixes:ee9db7d("Add unshare mode to pacstrap") Closes: #21
128 lines
3.5 KiB
Bash
128 lines
3.5 KiB
Bash
#!/bin/bash
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shopt -s extglob
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m4_include(common)
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setup=chroot_setup
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unshare=0
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usage() {
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cat <<EOF
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usage: ${0##*/} chroot-dir [command] [arguments...]
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-h Print this help message
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-N Run in unshare mode as a regular user
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-u <user>[:group] Specify non-root user and optional group to use
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If 'command' is unspecified, ${0##*/} will launch /bin/bash.
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Note that when using arch-chroot, the target chroot directory *should* be a
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mountpoint. This ensures that tools such as pacman(8) or findmnt(8) have an
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accurate hierarchy of the mounted filesystems within the chroot.
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If your chroot target is not a mountpoint, you can bind mount the directory on
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itself to make it a mountpoint, i.e. 'mount --bind /your/chroot /your/chroot'.
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EOF
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}
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resolve_link() {
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local target=$1
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local root=$2
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# If a root was given, make sure it ends in a slash.
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[[ -n $root && $root != */ ]] && root=$root/
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while [[ -L $target ]]; do
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target=$(readlink -m "$target")
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# If a root was given, make sure the target is under it.
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# Make sure to strip any leading slash from target first.
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[[ -n $root && $target != $root* ]] && target=$root${target#/}
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done
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printf %s "$target"
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}
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chroot_add_resolv_conf() {
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local chrootdir=$1
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local src=$(resolve_link /etc/resolv.conf)
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local dest=$(resolve_link "$chrootdir/etc/resolv.conf" "$chrootdir")
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# If we don't have a source resolv.conf file, there's nothing useful we can do.
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[[ -e $src ]] || return 0
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if [[ ! -e $dest ]]; then
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# There are two reasons the destination might not exist:
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#
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# 1. There may be no resolv.conf in the chroot. In this case, $dest won't exist,
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# and it will be equal to $1/etc/resolv.conf. In this case, we'll just exit.
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# The chroot environment must not be concerned with DNS resolution.
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#
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# 2. $1/etc/resolv.conf is (or resolves to) a broken link. The environment
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# clearly intends to handle DNS resolution, but something's wrong. Maybe it
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# normally creates the target at boot time. We'll (try to) take care of it by
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# creating a dummy file at the target, so that we have something to bind to.
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# Case 1.
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[[ $dest = $chrootdir/etc/resolv.conf ]] && return 0
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# Case 2.
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install -Dm644 /dev/null "$dest" || return 1
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fi
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chroot_add_mount "$src" "$dest" --bind
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}
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while getopts ':hNu:' flag; do
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case $flag in
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h)
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usage
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exit 0
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;;
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N)
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setup=unshare_setup
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unshare=1
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;;
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u)
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userspec=$OPTARG
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;;
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:)
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die '%s: option requires an argument -- '\''%s'\' "${0##*/}" "$OPTARG"
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;;
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?)
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die '%s: invalid option -- '\''%s'\' "${0##*/}" "$OPTARG"
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;;
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esac
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done
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shift $(( OPTIND - 1 ))
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(( $# )) || die 'No chroot directory specified'
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chrootdir=$1
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shift
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arch-chroot() {
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(( EUID == 0 )) || die 'This script must be run with root privileges'
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[[ -d $chrootdir ]] || die "Can't create chroot on non-directory %s" "$chrootdir"
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$setup "$chrootdir" || die "failed to setup chroot %s" "$chrootdir"
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chroot_add_resolv_conf "$chrootdir" || die "failed to setup resolv.conf"
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if ! mountpoint -q "$chrootdir"; then
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warning "$chrootdir is not a mountpoint. This may have undesirable side effects."
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fi
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chroot_args=()
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[[ $userspec ]] && chroot_args+=(--userspec "$userspec")
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SHELL=/bin/bash $pid_unshare chroot "${chroot_args[@]}" -- "$chrootdir" "${args[@]}"
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}
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args=("$@")
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if (( unshare )); then
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$mount_unshare bash -c "$(declare_all); arch-chroot"
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else
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arch-chroot
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fi
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