btrfs-scan from other repo

1 files changed, 157 insertions, 0 deletions

diff --git a/src/btrfs-scan b/src/btrfs-scan
new file mode 100755
index 0000000..ab9f771
--- /dev/null
+++ b/src/btrfs-scan
@@ -0,0 +1,157 @@
+#!/bin/bash
+set -e -o pipefail
+
+confdir=/etc/btrfs
+blacklist=$confdir/blacklist.txt
+
+with_subvolumes()
+{
+    btrfs subvolume list / -a |
+        while read _ id _ gen _ _ toplevel _ path
+        do
+            "$@"
+        done
+}
+
+fixup_path()
+{
+    if ! [ "$root" ]
+    then
+        case "$path" in
+            '<FS_TREE>'/* ) root=${path#*/} ;;
+            * ) exit 1 ;;
+        esac
+    fi
+    case "$path" in
+        '<FS_TREE>'/"$root"/* ) path_fixed=${path#*/$root} ;;
+        "$root"/* ) path_fixed=${path#$root} ;;
+        * ) return ;;
+    esac
+    compute_paths
+    "$@"
+}
+
+is_our_snapshot()
+{
+  case "$1" in
+    */.snapshot~* ) true ;;
+    *) false ;;
+  esac
+}
+
+filter_blacklist()
+{
+  if is_our_snapshot "$path_fixed"
+  then
+      if [ -e "$conf_name" ]
+      then
+             printf '%20s %s\n' delete "$conf_name" >&2
+             printf '%20s %s\n' '(snapshot) lose' "$path_fixed" >&2
+      fi
+      return
+
+  # Re-reading the blacklist file once per snapshot is not ideal,
+  # but is fine.
+  elif [ "$blacklist" -a -f "$blacklist" ]
+  then
+      while read pattern
+      do
+          if [[ $path_fixed == $pattern ]]
+          then
+              if [ -e "$conf_name" ]
+              then
+                  printf '%20s %s\n' delete "$conf_name" >&2
+              fi
+              printf '%20s %s\n' '(blacklist) lose' "$path_fixed" >&2
+              return
+          fi
+      done < "$blacklist"
+  fi
+  "$@"
+}
+
+compute_paths()
+{
+    source=$path_fixed
+    source_escaped=$(systemd-escape "$source")
+    conf_dir=/etc/btrfs/remotes
+    conf_name="$conf_dir"/$destination_host$source_escaped.json
+}
+
+mirror()
+{
+    if [ -e "$conf_name" ]
+    then
+        return
+    fi
+    set -- \
+        jq -c -n '{source: $source, destination: $destination}' \
+        --arg destination "$destination$source_escaped" \
+        --arg source "$source"
+
+    if [ ! "$NO_ACT" ]
+    then
+        conf_temp=$conf_name~$(date -Ins)
+        {
+            "$@" > "$conf_temp"
+            mv -T -- "$conf_temp" "$conf_name"
+            printf '%20s %s\n' 'add' "$path_fixed" >&2
+        } || {
+            rm -- "$conf_temp"
+            false
+        }
+    fi
+
+    if [ "$ONLY_ONCE" ]
+    then
+        exit 0
+    fi
+}
+
+usage()
+{
+cat <<END
+usage: $0 [-n] [-r]
+END
+}
+
+case "$0" in
+    ./* ) PATH=${0%/*}:$PATH ;;
+esac
+
+case "$(id -u)" in
+          0 ) ;;
+          * ) exec sudo --preserve-env=VERBOSE "$0" "$@" || exit ;;
+esac
+
+while [ $# -gt 0 ]
+do
+    case "$1" in
+        -- ) shift
+             break ;;
+        -n ) NO_ACT=y ;;
+        -r ) export RESUME=y ;;
+        -v ) VERBOSE=y ;;
+        --once ) ONLY_ONCE=y ;;
+        --destination ) DESTINATION=$2
+                        shift ;;
+        -* ) usage
+             exit 1 ;;
+        * ) break ;;
+    esac
+    shift
+done
+
+[ "$DESTINATION" ]
+
+destination_host=${DESTINATION%%:*}
+destination_basename=$(hostname) && [ "$destination_basename" ] || destination_basename=btrfs
+case "$DESTINATION" in
+    */ ) destination=$DESTINATION$destination_basename ;;
+    [a-zA-Z]* ) destination=$DESTINATION ;;
+    * ) exit 1 ;;
+esac
+
+ssh root@"$destination_host" true || read -p 'Could not log in.  Continue? '
+
+with_subvolumes fixup_path filter_blacklist mirror