diff options
| -rw-r--r-- | makechrootpkg.in | 93 |
1 files changed, 91 insertions, 2 deletions
diff --git a/makechrootpkg.in b/makechrootpkg.in index 5c4b530..7d3ebed 100644 --- a/makechrootpkg.in +++ b/makechrootpkg.in @@ -80,6 +80,95 @@ load_vars() { return 0 } +# Usage: btrfs_subvolume_id $SUBVOLUME +btrfs_subvolume_id() ( + set -o pipefail + LC_ALL=C btrfs subvolume show "$1" | sed -n 's/^\tSubvolume ID:\s*//p' +) + +# Usage: btrfs_subvolume_list_all $FILEPATH +# +# Given $FILEPATH somewhere on a mounted btrfs filesystem, print the +# ID and full path of every subvolume on the filesystem, one per line +# in the format "$ID $PATH", where $PATH is relative to the top-level +# subvolume (which might not be what is mounted). +# +# BUG: Due to limitations in the `btrfs` tool, this will not correctly +# list subvolumes whose path contains a space. +btrfs_subvolume_list_all() ( + set -o pipefail + + local mountpoint all + mountpoint="$(df --output=target "$1" | sed 1d)" || return + # The output of `btrfs subvolume list -a` is a space-separated + # sequence of "key value key value...". Unfortunately both + # keys and values can contain space, and there's no escaping + # or indication of when this happens. So we assume + # 1. ID is the first column + # 2. That no key or value will contain " path" + # 3. That the "path" value does not contain a space. + all="$(LC_ALL=C btrfs subvolume list -a "$mountpoint" | sed -r 's|^ID ([0-9]+) .* path (<FS_TREE>/)?(\S*).*|\1 \3|')" || return + + # Sanity check the output + local id path + while read -r id path; do + # ID should be numeric + [[ "$id" =~ ^-?[0-9]+$ ]] || return + # While a path could countain a space, the above code + # doesn't support it; if there is space, then it means + # we got a line not matching the expected format. + [[ "$path" != *' '* ]] || return + done <<<"$all" + + printf '%s\n' "$all" +) + +# Usage: btrfs_subvolume_list $SUBVOLUME +# +# Assuming that $SUBVOLUME is a btrfs subvolume, list all child +# subvolumes; from most deeply nested to most shallowly nested. +# +# This is intended to be a sane version of `btrfs subvolume list`. +btrfs_subvolume_list() { + local subvolume=$1 + + local id all path subpath + id="$(btrfs_subvolume_id "$subvolume")" || return + all="$(btrfs_subvolume_list_all "$subvolume")" || return + path=$(awk -v id="$id" '$1 == id { sub($1 FS, ""); print }' <<<"$all") + while read -r id subpath; do + if [[ "$subpath" = "$path"/* ]]; then + printf '%s\n' "${subpath#"${path}/"}" + fi + done <<<"$all" | LC_ALL=C sort --reverse +} + +# Usage: btrfs_subvolume_delete $SUBVOLUME +# +# Assuming that $SUBVOLUME is a btrfs subvolume, delete it and all +# subvolumes below it. +# +# This is intended to be a recursive version of +# `btrfs subvolume delete`. +btrfs_subvolume_delete() { + local dir="$1" + + # We store the result as a variable because we want to see if + # btrfs_subvolume_list fails or succeeds before we start + # deleting things. (Then we have to work around the subshell + # trimming the trailing newlines.) + local subvolumes + subvolumes="$(btrfs_subvolume_list "$dir")" || return + [[ -z "$subvolumes" ]] || subvolumes+=$'\n' + + local subvolume + while read -r subvolume; do + btrfs subvolume delete "$dir/$subvolume" || return + done < <(printf '%s' "$subvolumes") + + btrfs subvolume delete "$dir" +} + create_chroot() { # Lock the chroot we want to use. We'll keep this lock until we exit. lock 9 "$copydir.lock" "Locking chroot copy [%s]" "$copy" @@ -92,7 +181,7 @@ create_chroot() { stat_busy "Creating clean working copy [%s]" "$copy" if [[ "$chroottype" == btrfs ]] && ! mountpoint -q "$copydir"; then if [[ -d $copydir ]]; then - btrfs subvolume delete "$copydir" >/dev/null || + btrfs_subvolume_delete "$copydir" >/dev/null || die "Unable to delete subvolume %s" "$copydir" fi btrfs subvolume snapshot "$chrootdir/root" "$copydir" >/dev/null || @@ -114,7 +203,7 @@ create_chroot() { clean_temporary() { stat_busy "Removing temporary copy [%s]" "$copy" if [[ "$chroottype" == btrfs ]] && ! mountpoint -q "$copydir"; then - btrfs subvolume delete "$copydir" >/dev/null || + btrfs_subvolume_delete "$copydir" >/dev/null || die "Unable to delete subvolume %s" "$copydir" else # avoid change of filesystem in case of an umount failure |