From 4a1b788a52f3da681628fe5d56df6bfdf6092f3b Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Sat, 18 Oct 2025 12:31:49 -0700
Subject: [PATCH 01/22] Add baksnapperd-denotebak.sh [#45]

A backend for backing up DeNotebak snapshots.
---
 baksnapperd-denotebak.sh | 164 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 164 insertions(+)
 create mode 100644 baksnapperd-denotebak.sh

diff --git a/baksnapperd-denotebak.sh b/baksnapperd-denotebak.sh
new file mode 100644
index 0000000..65244a3
--- /dev/null
+++ b/baksnapperd-denotebak.sh
@@ -0,0 +1,164 @@
+#! /usr/bin/env bash
+
+# Baksnapperd-denotbak - Daemon used by baksnapper when backup DeNotebak snapshots
+
+# SPDX-FileCopyrightText: 2025  Fredrik Salomonsson <plattfot@posteo.net>
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+read -rd '' version <<EOF
+baksnapperd-denotebak (baksnapper) 2.4.0
+Copyright (C) 2025  Fredrik Salomonsson
+License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
+EOF
+
+shopt -s extglob
+
+function error {
+    echo "[ERROR] $1" 1>&2
+    exit 1
+}
+
+function warning {
+    echo -e "[Warning] $1" 1>&2
+}
+
+case "$1" in
+    version)
+        # Return what version of the API this is using.
+        #
+        # It always a single integer.
+        # No input.
+        echo 4
+        ;;
+    snapshot-type)
+        # Return what type of snapshot this backend supports
+        #
+        # No input.
+        echo denotebak
+        ;;
+    list-snapshots)
+        # List snapshots at location.
+        #
+        # Stripping any tags as they are volatile.
+        # 1 [in]: Path to the directory the snapshots are expected to be in.
+        shift
+        find "$1" -mindepth 1 -maxdepth 1 -type d -printf "%f\n" | sed 's/__.*//' | sort -g
+        ;;
+    verify-snapshot)
+        # Verify that a snapshot exist.
+        #
+        # 1 [in]: File path to a snapshot — sans tags.
+        # Return 0 if it exist, non-zero otherwise.
+        shift
+        test -d "$1"?(__*) || error "Snapshot $1 doesn't exist."
+        ;;
+    incomplete-snapshot)
+        # Check if a snapshot is incomplete.
+        #
+        # 1 [in]: Path to the directory the snapshot is in.
+        # 2 [in]: Name of the snapshot — sans tags.
+        # Return 0 if the snapshot is incomplete, non-zero otherwise.
+        shift
+        [[ $(btrfs property get "$1/$2"?(__*) ro) != "ro=true" ]]
+        ;;
+    create-location)
+        # Prepare destination to receive a snapshot.
+        #
+        # 1 [in]: Path to the directory the snapshots will be in.
+        shift
+        mkdir -p "$1"
+        ;;
+    receive-snapshot)
+        # Receive a snapshot.
+        #
+        # 1 [in]: Path to the directory the snapshot will be in.
+        # 2 [in]: Name of the snapshot — sans tags.
+        shift
+        btrfs receive "$1"
+        ;;
+    send-snapshot)
+        # Send a snapshot.
+        #
+        # 1 [in]: Path to the directory the snapshot is in.
+        # 2 [in]: Name of the snapshot — sans tags.
+        shift
+        btrfs send "$1/$2"?(__*)
+        ;;
+    send-incremental-snapshot)
+        # Only send what is different from the parent snapshot
+        #
+        # 1 [in]: File path to the parent snapshot — sans tags.
+        # 2 [in]: File path to the snapshot — sans tags.
+        shift
+        btrfs send -p "$1"?(__*) "$2"?(__*)
+        ;;
+    remove-snapshots)
+        # Remove all snapshots listed in the input.
+        #
+        # 1 [in]: Path to the directory the snapshots are in.
+        # 2+ [in]: Name of the snapshots — sans tags.
+        shift
+        dest_root=$1
+        shift
+        for snapshot in "$@"
+        do
+            if btrfs subvolume show "$dest_root/$snapshot"?(__*) &> /dev/null
+            then
+                echo "Deleting snapshot $snapshot"
+                btrfs subvolume delete "$dest_root/$snapshot"?(__*)
+            else
+                warning "Snapshot $snapshot does not match a DeNotebak snapshot, ignoring it."
+            fi
+        done
+        ;;
+    remove-broken-snapshot)
+        # Remove a broken snapshot.
+        #
+        # 1 [in]: Path to the directory the snapshot is in.
+        # 2 [in]: Name of the snapshot — sans tags.
+        shift
+        dest_root=$1
+        snapshot=$2
+        if btrfs subvolume show "$dest_root/$snapshot"?(__*) &> /dev/null
+        then
+            btrfs subvolume delete "$dest_root/$snapshot"?(__*)
+        fi
+        ;;
+    link-latest)
+        # Create symlink `latest` to the latest snapshot.
+        #
+        # 1 [in]: Path to the directory the snapshots are in.
+        set -x
+        shift
+        declare -a snapshots
+        if [[ -e "$1/latest" ]]; then
+            if [[ -h "$1/latest" ]]; then
+                rm "$1/latest"
+            else
+                error "$1/latest exists and is not a symbolic link. Link is not created."
+            fi
+        fi
+        for dir in $(find "$1" -maxdepth 1 -mindepth 1 -type d -printf "%P\n"|sort)
+        do
+            if btrfs subvolume show "$1/$dir" &> /dev/null && [[ ! -h "$1/$dir" ]]
+            then
+                snapshots+=("$dir")
+            fi
+        done
+        if  [ ${#snapshots[@]} -ne 0 ]; then
+            ln -sfn "${snapshots[-1]}" "$1/latest"
+        else
+            error "link-latest: No suitable snapshots at $1 (${#snapshots[@]})"
+        fi
+        ;;
+    --version)
+        echo -e "$version"
+        exit 0
+        ;;
+    *)
+        error "Unrecognized command '$1', bailing out!"
+        ;;
+esac

From 5c3c9b80cb273823a766fe80b4cfed8067324610 Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Sat, 18 Oct 2025 14:59:24 -0700
Subject: [PATCH 02/22] Add baksnapperd command `snapshot-type` [#45]

---
 baksnapperd.sh | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/baksnapperd.sh b/baksnapperd.sh
index 61f3469..9cdbb9c 100755
--- a/baksnapperd.sh
+++ b/baksnapperd.sh
@@ -35,6 +35,12 @@ case "$1" in
         # No input.
         echo 4
         ;;
+    snapshot-type)
+        # Return what type of snapshot this backend supports
+        #
+        # No input.
+        echo snapper
+        ;;
     list-snapshots)
         # List snapshots at location.
         #

From 976b42894fca66b9f634e6961205e5c99ad45e6c Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Sat, 18 Oct 2025 14:59:47 -0700
Subject: [PATCH 03/22] Add support to backup DeNotebak type snapshots

---
 baksnapper.sh | 69 ++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 54 insertions(+), 15 deletions(-)

diff --git a/baksnapper.sh b/baksnapper.sh
index 2bbd850..a15bf9e 100755
--- a/baksnapper.sh
+++ b/baksnapper.sh
@@ -466,6 +466,16 @@ then
         fi
     fi
 
+    if [[ $sender_version -ge 4 && $($sender snapshot-type) != "snapper" ]]
+    then
+        error "config interface only supports snapper"
+    fi
+
+    if [[ $receiver_version -ge 4 && $($receiver snapshot-type) != "snapper" ]]
+    then
+        error "config interface only supports snapper"
+    fi
+
     src_root=${subvolume:?}/.snapshots
     dest_root="$dest/$p_config"
 elif [[ -n "$p_src" && -n "$p_dest" ]]
@@ -523,6 +533,32 @@ else
     error "You need to specify the SOURCE and DEST or the config name to backup!"
 fi
 
+# Get what snapshot type the daemon supports
+# 1 [out]: variable where it will save the snapshot type.
+# 2 [in]: variable that contains the baksnapperd backend
+# 3 [in]: the version of the baksnapperd backend
+function get-snapshot-type {
+    declare -n snapshot_type=$1
+    if [[ $3 -ge 4 ]]
+    then
+        snapshot_type=$(${!2} snapshot-type)
+    else
+        # shellcheck disable=SC2034
+        backend=snapper
+    fi
+}
+get-snapshot-type sender_snapshot_type sender "$sender_version"
+get-snapshot-type receiver_snapshot_type receiver "$receiver_version"
+
+# shellcheck disable=SC2154
+if [[ "$sender_snapshot_type" != "$receiver_snapshot_type" ]]
+then
+    error "Sender and receiver expects different snapshot types: sender: \
+$sender_snapshot_type, receiver: $receiver_snapshot_type"
+fi
+
+snapshot_type=$sender_snapshot_type
+
 ## Setup signals ###############################################################
 # EXIT   --> if notify-send is installed, inform the user; always cleanup
 if hash notify-send 2> /dev/null
@@ -645,15 +681,17 @@ function single-backup {
     local start_time
     start_time=$(date +%s)
 
-    $receiver create-snapshot "$dest_root" "$1" ||
-        error "Failed to create snapshot at backup location!"
-
-    if ! $sender send-info "$src_root" "$1" | $receiver receive-info "$dest_root" "$1"
+    if [[ "$snapshot_type" == "snapper" ]]
     then
-        $receiver remove-broken-snapshot "$dest_root" "$1"
-        error "Failed to send snapshot info!"
-    fi
+        $receiver create-snapshot "$dest_root" "$1" ||
+            error "Failed to create snapshot at backup location!"
 
+        if ! $sender send-info "$src_root" "$1" | $receiver receive-info "$dest_root" "$1"
+        then
+            $receiver remove-broken-snapshot "$dest_root" "$1"
+            error "Failed to send snapshot info!"
+        fi
+    fi
     printf "%s\t\t%s\t" "${dest_root}" "${1}" >>"${p_summary}"
     exec 4>"${p_temp_dir}/${1}"
     if ! $sender send-snapshot "$src_root" "$1" | tee >( wc -c >&4 ) | $receiver receive-snapshot "$dest_root" "$1"
@@ -676,16 +714,17 @@ function incremental-backup {
     start_time=$(date +%s)
 
     echo "Incremental backup $1 $2"
-
-    $receiver create-snapshot "$dest_root" "$2" ||
-        error "Failed to create snapshot at backup location!"
-
-    if ! $sender send-info "$src_root" "$2" | $receiver receive-info "$dest_root" "$2"
+    if [[ "$snapshot_type" == "snapper" ]]
     then
-        $receiver remove-broken-snapshot "$dest_root" "$1"
-        error "Failed to send snapshot info!"
-    fi
+        $receiver create-snapshot "$dest_root" "$2" ||
+            error "Failed to create snapshot at backup location!"
 
+        if ! $sender send-info "$src_root" "$2" | $receiver receive-info "$dest_root" "$2"
+        then
+            $receiver remove-broken-snapshot "$dest_root" "$1"
+            error "Failed to send snapshot info!"
+        fi
+    fi
     printf "%s\t%s\t%s\t" "${dest_root}" "${1}" "${2}" >>"${p_summary}"
     exec 4>"${p_temp_dir}/${2}"
     if ! $sender send-incremental-snapshot "$src_root/"{"$1","$2"} \

From d2c78a3d184ff084f03373ba75f163d9ff8cfbd4 Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Sat, 25 Oct 2025 16:57:03 -0700
Subject: [PATCH 04/22] Install baksnapperd-denotebak backend [#45]

---
 meson.build | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/meson.build b/meson.build
index 49d520c..57879d2 100644
--- a/meson.build
+++ b/meson.build
@@ -30,6 +30,16 @@ baksnapperd = custom_target(
   install_tag: 'runtime',
 )
 
+baksnapperd_denotebak = custom_target(
+  command: [install_cmd, '@INPUT@', '@OUTPUT@'],
+  input: 'baksnapperd-denotebak.sh',
+  output: 'baksnapperd-denotebak',
+  install: true,
+  install_dir: 'bin',
+  install_mode: 'rwxr-xr-x',
+  install_tag: 'runtime',
+)
+
 bsconf_root = get_option('bsconf-root')
 if bsconf_root == ''
   bsconf_root = get_option('sysconfdir')

From b11303b20601ce8a9dec41ff7931415e3db78f2c Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Sat, 1 Nov 2025 12:31:39 -0700
Subject: [PATCH 05/22] Add support for DeNotebak in baksnapper [#45]

---
 baksnapper.sh | 91 +++++++++++++++++++++++++--------------------------
 1 file changed, 44 insertions(+), 47 deletions(-)

diff --git a/baksnapper.sh b/baksnapper.sh
index a15bf9e..b77ce11 100755
--- a/baksnapper.sh
+++ b/baksnapper.sh
@@ -559,6 +559,14 @@ fi
 
 snapshot_type=$sender_snapshot_type
 
+# Using a bitmap to represent where a snapshot is located:
+# 0b01 → exist at the source
+# 0b10 → exist at the destination
+# 0b11 → exist at both locations, i.e. common
+declare -A common
+only_in_src=()
+only_in_dest=()
+
 ## Setup signals ###############################################################
 # EXIT   --> if notify-send is installed, inform the user; always cleanup
 if hash notify-send 2> /dev/null
@@ -633,28 +641,20 @@ function gather-receiver-snapshots {
 # only_in_src: only exist at the source
 # only_in_dest: only exist at the destination
 function compare-snapshots {
-
     idx_src=0
     idx_dest=0
-
-    # Using a bitmap to represent where a snapshot is located:
-    # 0b01 → exist at the source
-    # 0b10 → exist at the destination
-    # 0b11 → exist at both locations, i.e. common
-    common=()
     only_in_src=()
     only_in_dest=()
-
     # NOTE: the snapshots must be sorted in ascending order hence the
     # "sort -g" when getting the snapshots.
     while (( idx_src < num_src_snapshots && idx_dest < num_dest_snapshots ))
     do
-        if [ "${src_snapshots[idx_src]}" -eq "${dest_snapshots[idx_dest]}" ]
+        if [[ "${src_snapshots[idx_src]}" == "${dest_snapshots[idx_dest]}" ]]
         then
             common["${src_snapshots[idx_src]}"]=0b11
             ((++idx_src))
             ((++idx_dest))
-        elif [ "${src_snapshots[idx_src]}" -lt "${dest_snapshots[idx_dest]}" ]
+        elif [[ "${src_snapshots[idx_src]}" < "${dest_snapshots[idx_dest]}" ]]
         then
             only_in_src+=("${src_snapshots[idx_src]}")
             ((++idx_src))
@@ -806,62 +806,59 @@ function backup {
         return 0
     fi
 
+    # Find the first common snapshot that is lower than the specified
+    # snapshot.
+    #
+    # 1 [out]: parent snapshot
+    # 2 [in]: snapshot
+    function find-parent {
+        declare -n out=$1
+        local snapshot=$2
+        local idx=${num_src_snapshots}-1
+        for (( ; idx >= 0; --idx ))
+        do
+            if [[ "${src_snapshots[idx]}" < "$snapshot" && \
+                      ${common[${src_snapshots[idx]}]} == 0b11 ]]
+            then
+                break
+            fi
+        done
+        out=${src_snapshots[idx]}
+    }
+
     if [[ $p_all == 0 ]]
     then
-        local common_ids=("${!common[@]}")
-        local common_last=${common_ids[-1]}
         # Check that it's not already synced
-        if [[ "$common_last" == "$p_snapshot" ]]
+        if [[ ${common[$p_snapshot]} == 0b11 ]]
         then
-            error "Already synced the last snapshot."
+            error "Already synced snapshot $p_snapshot."
         fi
-        incremental-backup "$common_last" "$p_snapshot"
+        local parent
+        find-parent parent "$p_snapshot"
+        incremental-backup "$parent" "$p_snapshot"
         return 0
     else
-        local -a src_and_common
-        for snapshot in "${!common[@]}"
-        do
-            # These exist at both locations → 0b01
-            src_and_common["$snapshot"]=0b11
-        done
-        for snapshot in "${only_in_src[@]}"
-        do
-            # These only exist at the source → 0b01
-            src_and_common["$snapshot"]=0b01
-        done
-        local num_snapshots=${#src_and_common[@]}
         # Find the first common snapshot that is lower than the first
         # source only snapshot. This will be the start of the incremental
         # backup. If no one is found it will use the lowest common one.
-        local first_src_snapshot=${only_in_src[0]}
-        local snapshot_ids=("${!src_and_common[@]}")
-        local idx=${num_snapshots}-1
-        for (( ; idx >= 0; --idx ))
-        do
-            if [[ ${snapshot_ids[idx]} -lt $first_src_snapshot ]]
-            then
-                if [[ ${src_and_common[${snapshot_ids[idx]}]} == 0b11 ]]
-                then
-                    break
-                fi
-            fi
-        done
-        incremental-backup "${snapshot_ids[idx]}" "$first_src_snapshot"
-        src_and_common["${snapshot_ids[idx]}"]=0b11
+        first_src_snapshot="${only_in_src[0]}"
+        find-parent parent "$first_src_snapshot"
+        incremental-backup "$parent" "$first_src_snapshot"
+        common["${src_snapshots[idx]}"]=0b11
         for (( src_idx = 1; src_idx < num_src_only; ++src_idx ))
         do
-            # Find the source only snapshot in the snapshot_ids
+            # Find the next source snapshot to send
             local src_snapshot=${only_in_src[src_idx]}
-            for (( ; idx < num_snapshots; ++idx ))
+            for (( ; idx < num_src_snapshots; ++idx ))
             do
-                if [[ ${snapshot_ids[idx]} -eq $src_snapshot ]]
+                if [[ "${src_snapshots[idx]}" == "$src_snapshot" ]]
                 then
                     break
                 fi
             done
             # Use the common snapshot previous to it as the parent
-            incremental-backup "${snapshot_ids[idx-1]}" "$src_snapshot"
-            src_and_common["$src_snapshot"]=0b11
+            incremental-backup "${src_snapshots[idx-1]}" "$src_snapshot"
+            common["$src_snapshot"]=0b11
         done
     fi
 }

From 7f1ba5b2aa3279cee4ccca810562c9d37abb9c45 Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Sat, 25 Oct 2025 15:49:47 -0700
Subject: [PATCH 06/22] test: Use make-snapshot-from when reading in input for
 sender

Allows to tweak things on the sender side.
---
 tests/runner.scm | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/runner.scm b/tests/runner.scm
index 5ad621f..d446cda 100755
--- a/tests/runner.scm
+++ b/tests/runner.scm
@@ -352,8 +352,8 @@ Fredrik \"PlaTFooT\" Salomonsson
       (format #t "  expected: ~a~%" expected)
       (let ((exit-status 0)
             (sender-snapshots
-             (map (lambda (id)
-                    (make-snapshot id #f 'valid))
+             (map (lambda (input)
+                    (make-snapshot-from input))
                   sender))
             (receiver-snapshots
              (map (lambda (input)

From 084cbad83d80138dd5b450dbef6bf5d3e8ca350d Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Sat, 25 Oct 2025 15:51:09 -0700
Subject: [PATCH 07/22] test: Move `create-snapshot` out from
 `create-snapper-snapshot`

---
 tests/runner.scm | 36 ++++++++++++++++++++++++------------
 1 file changed, 24 insertions(+), 12 deletions(-)

diff --git a/tests/runner.scm b/tests/runner.scm
index d446cda..88d0d76 100755
--- a/tests/runner.scm
+++ b/tests/runner.scm
@@ -53,6 +53,29 @@
        (('state . s) s)
        (_ 'valid)))))
 
+(define* (create-snapshot path snapshot #:key valid?)
+  "Create a dummy snapshot at PATH.
+
+It will have the following structure:
+
+PATH
+└── data
+
+The file `data` will contain; snapshot=ID, where ID is the id from
+SNAPSHOT; parent=PARENT, where PARAENT is the parent from SNAPSHOT.
+If parent is #f it will skip it.
+
+It will also contain `ro=true` if VALID? evaluates to true."
+(mkdir path)
+(let ((port (open-output-file
+             (string-append path file-name-separator-string "data"))))
+  (and-let* ((parent (snapshot-parent snapshot)))
+    (format port "parent=~a~%" parent))
+  (format port "snapshot=~a~%" (snapshot-id snapshot))
+  (when valid?
+    (format port "ro=true~%"))
+  (close-port port)))
+
 (define (create-snapper-snapshot path snapshot)
   "Create dummy snapper snapshot at PATH for SNAPSHOT.
 
@@ -93,18 +116,7 @@ incomplete.  It will have both `info.xml` and `snapshot`.  But the
          (create-info.xml (lambda ()
                            (close-port
                             (open-output-file
-                             (string-append path "/info.xml")))))
-         (create-snapshot (lambda* (#:key valid?)
-                            (mkdir snapshot-dir)
-                            (let ((port (open-output-file
-                                         (string-append snapshot-dir
-                                                        file-name-separator-string "data"))))
-                              (and-let* ((parent (snapshot-parent snapshot)))
-                                (format port "parent=~a~%" parent))
-                              (format port "snapshot=~a~%" (snapshot-id snapshot))
-                              (when valid?
-                                (format port "ro=true~%"))
-                              (close-port port)))))
+                             (string-append path "/info.xml"))))))
     (match (snapshot-state snapshot)
       ('valid
        (mkdir path)

From a2d4ed1fec007e6366ed2689b68109f2fe00ac32 Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Sat, 25 Oct 2025 15:52:03 -0700
Subject: [PATCH 08/22] test: Add tags field to `<snapshot>`

This to be able to set tags for denotebak snapshots.
---
 tests/runner.scm | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/tests/runner.scm b/tests/runner.scm
index 88d0d76..7900f89 100755
--- a/tests/runner.scm
+++ b/tests/runner.scm
@@ -23,11 +23,12 @@
   (string-join paths file-name-separator-string))
 
 (define-record-type <snapshot>
-  (make-snapshot id parent state)
+  (make-snapshot id parent state tags)
   snapshot?
   (id snapshot-id)
   (parent snapshot-parent)
-  (state snapshot-state))
+  (state snapshot-state)
+  (tags snapshot-tags))
 
 (define (make-snapshot-from input)
   "Parse INPUT and create a snapshot from it."
@@ -37,12 +38,13 @@
           (map
            (lambda (metadatum)
              (match (string-split metadatum #\=)
-              (("p" parent) (cons 'parent parent))
-              (("s" state)
-               (let ((state-sym (string->symbol state)))
-                 (match state-sym
+               (("p" parent) (cons 'parent parent))
+               (("s" state)
+                (let ((state-sym (string->symbol state)))
+                  (match state-sym
                     ((or 'valid 'empty 'no-info 'no-snapshot 'incomplete)
-                     (cons 'state state-sym)))))))
+                     (cons 'state state-sym)))))
+               (("t" tags) (cons 'tags tags))))
            (cdr info))))
     (make-snapshot
      id
@@ -51,7 +53,10 @@
        (_ #f))
      (match (assoc 'state metadata)
        (('state . s) s)
-       (_ 'valid)))))
+       (_ 'valid))
+     (match (assoc 'state metadata)
+       (('tags . t) t)
+       (_ #f)))))
 
 (define* (create-snapshot path snapshot #:key valid?)
   "Create a dummy snapshot at PATH.
@@ -121,19 +126,19 @@ incomplete.  It will have both `info.xml` and `snapshot`.  But the
       ('valid
        (mkdir path)
        (create-info.xml)
-       (create-snapshot #:valid? #t))
+       (create-snapshot snapshot-dir snapshot #:valid? #t))
       ('empty
        (mkdir path))
       ('no-info
        (mkdir path)
-       (create-snapshot #:valid? #t))
+       (create-snapshot snapshot-dir snapshot #:valid? #t))
       ('no-snapshot
        (mkdir path)
        (create-info.xml))
       ('incomplete
        (mkdir path)
        (create-info.xml)
-       (create-snapshot #:valid? #f)))))
+       (create-snapshot snapshot-dir snapshot #:valid? #f)))))
 
 (define (check-snapshot-input value)
   "Verify the input for receiver or expected."
@@ -214,7 +219,8 @@ Where DATA is in the format of what you get calling `read-snapshots'."
        ((#t () _)
         'no-snapshot)
        (_
-        'incomplete)))))
+        'incomplete))
+     #f)))
 
 (define (check-latest expected-latest receiver-dir)
   "Verify that EXPECTED-LATEST points to the expected snapshot.

From 25d50a3455125237de4cfab5270fdf4c729ad7e0 Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Sat, 25 Oct 2025 16:56:42 -0700
Subject: [PATCH 09/22] test: Add support for DeNotebak snapshots in runner

---
 tests/runner.scm | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/tests/runner.scm b/tests/runner.scm
index 7900f89..9e94f23 100755
--- a/tests/runner.scm
+++ b/tests/runner.scm
@@ -63,15 +63,22 @@
 
 It will have the following structure:
 
-PATH
+PATH[__<tags>]
 └── data
 
 The file `data` will contain; snapshot=ID, where ID is the id from
 SNAPSHOT; parent=PARENT, where PARAENT is the parent from SNAPSHOT.
 If parent is #f it will skip it.
 
+It will append the tags string to the path, separated by `__`, if that
+does not evaluate to false.
+
 It will also contain `ro=true` if VALID? evaluates to true."
-(mkdir path)
+(mkdir
+ (match (snapshot-tags snapshot)
+   (#f path)
+   (tags (string-append path "__" tags))))
+
 (let ((port (open-output-file
              (string-append path file-name-separator-string "data"))))
   (and-let* ((parent (snapshot-parent snapshot)))
@@ -154,6 +161,7 @@ incomplete.  It will have both `info.xml` and `snapshot`.  But the
                   (_
                    (format (current-error-port) "unsupported state: ~a~%" state)
                    #f)))
+               (("t" tags) #t)
                (_
                 (format (current-error-port) "invalid snapshot syntax: ~a~%" metadata)
                 #f))
@@ -278,7 +286,7 @@ Return the path to the modified CONFIGFILE if it is defined otherwise #f."
 (define (main args)
   (let* ((option-spec
           `((config (single-char #\c) (value #t))
-            (sender (single-char #\s) (value #t))
+            (sender (single-char #\s) (value #t) (predicate ,check-snapshot-input))
             (latest (single-char #\l) (value #t))
             (receiver (single-char #\r) (value #t) (predicate ,check-snapshot-input))
             (expected (single-char #\e) (value #t) (predicate ,check-snapshot-input))
@@ -350,6 +358,7 @@ Fredrik \"PlaTFooT\" Salomonsson
     (let* ((parse-comma-option
             (lambda (input)
               (remove string-null? (string-split (option-ref options input "")  #\,))))
+           (type (string->symbol (option-ref options 'type "snapper")))
            (config (option-ref options 'config "root"))
            (sender (parse-comma-option 'sender))
            (receiver (parse-comma-option 'receiver))
@@ -361,7 +370,10 @@ Fredrik \"PlaTFooT\" Salomonsson
            (sender-dir (path-join test-dir config ".snapshots"))
            (receiver-root-dir (path-join test-dir "receiver"))
            (receiver-dir (path-join receiver-root-dir config))
-           (configfile (option-ref options 'configfile #f)))
+           (configfile (option-ref options 'configfile #f))
+           (create-snapshot-func (match type
+                                   ('denotebak create-denotebak-snapshot)
+                                   (_ create-snapper-snapshot))))
       ;; Needed for nftw to be able to read the directory
       (chmod test-dir #o744)
       (format #t "Test ~a~%" test-dir)
@@ -389,7 +401,7 @@ Fredrik \"PlaTFooT\" Salomonsson
         (mkdir sender-dir)
         (for-each
          (lambda (snapshot)
-           (create-snapper-snapshot
+           (create-snapshot-func
             (path-join sender-dir (snapshot-id snapshot))
             snapshot))
          sender-snapshots)
@@ -398,7 +410,7 @@ Fredrik \"PlaTFooT\" Salomonsson
         (mkdir receiver-dir)
         (for-each
          (lambda (snapshot)
-           (create-snapper-snapshot
+           (create-snapshot-func
             (path-join receiver-dir (snapshot-id snapshot))
             snapshot))
          receiver-snapshots)

From 46ccda1e18ef9840497d5e01fe945935dd0b8a07 Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Sun, 9 Nov 2025 17:35:45 -0800
Subject: [PATCH 10/22] test: Add `make-snapshot-from-denotebak-read` [#45]

To be able to read back DeNotebak snapshots.
---
 tests/runner.scm | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/tests/runner.scm b/tests/runner.scm
index 9e94f23..d1d5aff 100755
--- a/tests/runner.scm
+++ b/tests/runner.scm
@@ -230,6 +230,36 @@ Where DATA is in the format of what you get calling `read-snapshots'."
         'incomplete))
      #f)))
 
+(define (make-snapshot-from-denotebak-read data)
+  "Create a snapshot from DATA.
+
+Where DATA is in the format of what you get calling `read-snapshots'."
+  (match data
+    (('latest . #t) (make-snapshot 'latest #f 'valid #f))
+    (_
+     (let* ((id (car data))
+            (get (lambda (key alist default)
+                   (match (assoc key alist)
+                     ((key . v) v)
+                     (_ default))))
+            (metadata (cadr data))
+            (snapshot-info (get "snapshot" metadata #f))
+            (read-only (match (assoc "ro" metadata)
+                         (("ro" . "true") #t)
+                         (_ #f)))
+            (parent (get "parent" metadata #f)))
+       (make-snapshot
+        id
+        parent
+        (match (list snapshot-info read-only)
+          ((#f _)
+           'no-snapshot)
+          ((snapshot #t)
+           'valid)
+          (_
+           'incomplete))
+        #f)))))
+
 (define (check-latest expected-latest receiver-dir)
   "Verify that EXPECTED-LATEST points to the expected snapshot.
 

From 7af0b60a5c9ef8e02f2ae1dcc3966f3ecf38bc3e Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Sun, 9 Nov 2025 19:09:59 -0800
Subject: [PATCH 11/22] test: Fix mock btrfs command to work with both snapper
 and DeNotebak [#45]

Changed it to take the name of the snapshot it received rather than
hard code the name to "snapshot".
---
 tests/bin/btrfs | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/tests/bin/btrfs b/tests/bin/btrfs
index 2ddb258..f8e8f5c 100755
--- a/tests/bin/btrfs
+++ b/tests/bin/btrfs
@@ -60,11 +60,13 @@ do
             ;;
     esac
 done
-
 function subvolume {
     case "$1" in
+        show)
+            test -d "$2"
+            ;;
         delete)
-            rm -rf -- "$1"
+            rm -rf -- "$2"
             ;;
         *)
             >&2 echo "unsupported subcommand to subvolume: $1"
@@ -82,16 +84,21 @@ function receive {
     snapshot_parent=${data%:*}
     if [[ -n "$snapshot_parent" ]]
     then
-        snapshot_parent=$(basename "$(dirname "$snapshot_parent")")
+        if [[ "$(basename "$snapshot_parent")" == "snapshot" ]]
+        then
+            snapshot_parent=$(basename "$(dirname "$snapshot_parent")")
+        else
+            snapshot_parent=$(basename "$snapshot_parent")
+        fi
     fi
     snapshot=${data#*:}
-
-    mkdir -p "$1/snapshot"
+    path="$1/$(basename "$snapshot")"
+    mkdir -p "$path"
     {
         echo "parent=$snapshot_parent"
         echo "snapshot=$snapshot"
         echo "ro=true"
-    } > "$1/snapshot/data"
+    } > "$path/data"
 }
 
 function property {

From 7d2b2b888cc00f61e4834b08c250a585f9eeea71 Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Sat, 25 Oct 2025 16:57:20 -0700
Subject: [PATCH 12/22] test: Initial test for DeNotebak [#45]

---
 meson.build | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/meson.build b/meson.build
index 57879d2..4b6c2d5 100644
--- a/meson.build
+++ b/meson.build
@@ -399,3 +399,44 @@ test(
   ],
   should_fail: true,
 )
+
+test(
+  'denotebak',
+  runner,
+  env: test_env,
+  args: [
+    '--sender', ','.join([
+      '20251023T130000:t=dailies',
+      '20251023T180000:t=dailies',
+      '20251024T090000:t=dailies',
+      '20251024T130000:t=dailies',
+      '20251024T180000:t=dailies',
+      '20251025T120000',
+      '20251025T130000:t=dailies',
+      '20251025T140000:t=hourly',
+      '20251025T150000:t=hourly',
+      '20251025T160000:t=hourly']),
+    '--expected', ','.join([
+      '20251023T130000',
+      '20251023T180000:p=20251023T130000',
+      '20251024T090000:p=20251023T180000',
+      '20251024T130000:p=20251024T090000',
+      '20251024T180000:p=20251024T130000',
+      '20251025T120000:p=20251024T180000',
+      '20251025T130000:p=20251025T120000',
+      '20251025T140000:p=20251025T130000',
+      '20251025T150000:p=20251025T140000',
+      '20251025T160000:p=20251025T150000']),
+    '--type', 'denotebak',
+    '--src-dest',
+    '--',
+    baksnapper[0].full_path(),
+    '--daemon', baksnapperd_denotebak[0].full_path(),
+    '--all',
+  ],
+  depends: [
+    baksnapper,
+    baksnapperd_denotebak,
+  ],
+  suite: 'backup',
+)

From 60e02c580fd6f217a8967baf04064a16af65df64 Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Sun, 9 Nov 2025 17:39:17 -0800
Subject: [PATCH 13/22] test: Add support to switch the backend for reading in
 snapshots [#45]

To be able to test both snapper and DeNotebak
---
 tests/runner.scm | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tests/runner.scm b/tests/runner.scm
index d1d5aff..f1c6593 100755
--- a/tests/runner.scm
+++ b/tests/runner.scm
@@ -196,7 +196,7 @@ incomplete.  It will have both `info.xml` and `snapshot`.  But the
               (read-snapshots (cons (path-join parent name) child)))
             children)))))
 
-(define (make-snapshot-from-read data)
+(define (make-snapshot-from-snapper-read data)
   "Create a snapshot from DATA.
 
 Where DATA is in the format of what you get calling `read-snapshots'."
@@ -403,7 +403,10 @@ Fredrik \"PlaTFooT\" Salomonsson
            (configfile (option-ref options 'configfile #f))
            (create-snapshot-func (match type
                                    ('denotebak create-denotebak-snapshot)
-                                   (_ create-snapper-snapshot))))
+                                   (_ create-snapper-snapshot)))
+           (make-snapshot-from-read (match type
+                                   ('denotebak make-snapshot-from-denotebak-read)
+                                   (_ make-snapshot-from-snapper-read))))
       ;; Needed for nftw to be able to read the directory
       (chmod test-dir #o744)
       (format #t "Test ~a~%" test-dir)

From 0b0920fec204ce445928c1309031b98173627038 Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Wed, 12 Nov 2025 21:59:01 -0800
Subject: [PATCH 14/22] test: Add `create-denotebak-snapshot` procedure [#45]

To be able to create dummy DeNotebak snapshots.
---
 tests/runner.scm | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/tests/runner.scm b/tests/runner.scm
index f1c6593..d3ed138 100755
--- a/tests/runner.scm
+++ b/tests/runner.scm
@@ -88,6 +88,30 @@ It will also contain `ro=true` if VALID? evaluates to true."
     (format port "ro=true~%"))
   (close-port port)))
 
+(define (create-denotebak-snapshot path snapshot)
+  "Create dummy DeNotebak snapshot at PATH for SNAPSHOT.
+
+A DeNotebak snapshot is just a btrfs snapshot.  This will mock the
+structure with the following:
+
+PATH[__<tags>]
+└── data
+
+The state in SNAPSHOT specify what state it should create the
+snapshot, accepted values are:
+
+- valid: a complete snapshot as described above.  With `ro=true` added
+to the `data` file.
+
+- incomplete: a broken snapshot which snapshot directory is
+incomplete.  Which is indicated by the `ro=true` attribute will be
+missing in the `data` file."
+  (match (snapshot-state snapshot)
+    ('valid
+     (create-snapshot path snapshot #:valid? #t))
+    ('incomplete
+     (create-snapshot path snapshot #:valid? #f))))
+
 (define (create-snapper-snapshot path snapshot)
   "Create dummy snapper snapshot at PATH for SNAPSHOT.
 

From bb88df4e2f3aaed8a7bcbb82bb0e92be014adc8a Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Wed, 12 Nov 2025 22:05:00 -0800
Subject: [PATCH 15/22] test: Swap the order for `conf` and `test_entry` in the
 meson tests

Since it's mostly the `test_entry` that you'll be changing.  Having
that first makes more sense.
---
 meson.build | 346 +++++++++++++++++++++++-----------------------------
 1 file changed, 153 insertions(+), 193 deletions(-)

diff --git a/meson.build b/meson.build
index 4b6c2d5..2af34ce 100644
--- a/meson.build
+++ b/meson.build
@@ -117,190 +117,190 @@ test_configuration = {
     'VERBOSE': 'NO',
   },
 }
-foreach conf: [
+foreach test_entry: [
   {
-    'suffix': '-config',
-    'runner-args': [],
-    'baksnapper-args': ['--config', 'root'],
-    'configfile': false,
-    'suite': ['config'],
+    'name': 'default',
+    'runner-args': [
+      '--sender', '1,2,3',
+      '--expected', '3',
+    ],
+    'baksnapper-args': [
+      baksnapper[0].full_path(),
+      '--daemon', baksnapperd[0].full_path(),
+    ],
+    'configfile': 'default',
+    'configfile-baksnapper-args': [],
+    'suite': ['backup'],
   },
   {
-    'suffix': '-src-dest',
-    'runner-args': ['--src-dest'],
-    'baksnapper-args': [],
-    'configfile': false,
-    'suite': ['src-dest'],
+    'name': 'latest',
+    'runner-args': [
+      '--sender', '1,2,3',
+      '--expected', '3',
+      '--expected-latest', '3',
+    ],
+    'baksnapper-args': [
+      baksnapper[0].full_path(),
+      '--daemon', baksnapperd[0].full_path(),
+      '--link',
+    ],
+    'configfile': 'latest',
+    'configfile-baksnapper-args': [],
+    'suite': ['latest'],
   },
   {
-    'suffix': '-configfile',
-    'runner-args': [],
-    'baksnapper-args': [],
-    'configfile': true,
-    'suite': ['configfile'],
+    'name': 'prune',
+    'runner-args': [
+      '--sender', '1,2,3,6,7,8',
+      '--receiver', '1,2,3,4,5,6',
+      '--expected', '1,2,3,6,8:p=6',
+    ],
+    'baksnapper-args': [
+      baksnapper[0].full_path(),
+      '--daemon', baksnapperd[0].full_path(),
+      '--prune',
+    ],
+    'configfile': 'prune',
+    'configfile-baksnapper-args': [],
+    'suite': ['prune'],
   },
   {
-    'suffix': '-configfile-path',
-    'runner-args': ['--path-config'],
-    'baksnapper-args': [],
-    'configfile': true,
-    'suite': ['configfile', 'config'],
+    'name': 'backup-2',
+    'runner-args': [
+      '--sender', '1,2,3',
+      '--expected', '2',
+    ],
+    'baksnapper-args': [
+      baksnapper[0].full_path(),
+      '--daemon', baksnapperd[0].full_path(),
+      '--snapshot', '2',
+    ],
+    'configfile': 'default',
+    'configfile-baksnapper-args': [],
+    'suite': ['backup'],
   },
   {
-    'suffix': '-configfile-src-dest',
-    'runner-args': ['--src-dest'],
-    'baksnapper-args': [],
-    'configfile': true,
-    'suite': ['configfile', 'src-dest'],
+    'name': 'delete-1',
+    'runner-args': [
+      '--sender', '1,2,3',
+      '--receiver', '1,2,3',
+      '--expected', '2,3',
+    ],
+    'baksnapper-args': [
+      baksnapper[0].full_path(),
+      '--daemon', baksnapperd[0].full_path(),
+      '--delete', '1',
+    ],
+    'configfile': 'default',
+    'configfile-baksnapper-args': [],
+    'suite': ['delete'],
   },
   {
-    'suffix': '-configfile-src',
-    'runner-args': ['--src-dest', '--src-config'],
-    'baksnapper-args': [],
-    'configfile': true,
-    'suite': ['configfile', 'src-dest'],
+    'name': 'delete-1,3',
+    'runner-args': [
+      '--sender', '1,2,3',
+      '--receiver', '1,2,3',
+      '--expected', '2',
+    ],
+    'baksnapper-args': [
+      baksnapper[0].full_path(),
+      '--daemon', baksnapperd[0].full_path(),
+      '--delete', '1,3',
+    ],
+    'configfile': 'default',
+    'configfile-baksnapper-args': [],
+    'suite': ['delete'],
   },
   {
-    'suffix': '-configfile-dest',
-    'runner-args': ['--src-dest', '--dest-config'],
-    'baksnapper-args': [],
-    'configfile': true,
-    'suite': ['configfile', 'src-dest'],
+    'name': 'backup-with-right-parent',
+    'runner-args': [
+      '--sender', '64,65,76,83,91,92,93',
+      '--receiver', '64,66:p=64,76:p=66,83:p=76,91:p=83,92:p=83',
+      '--expected', '64,66:p=64,76:p=66,83:p=76,91:p=83,92:p=83,93:p=92',
+    ],
+    'baksnapper-args': [
+      baksnapper[0].full_path(),
+      '--daemon', baksnapperd[0].full_path(),
+    ],
+    'configfile': 'default',
+    'configfile-baksnapper-args': [],
+    'suite': ['backup'],
   },
+  # https://github.com/plattfot/baksnapper/issues/27
   {
-    'suffix': '-configfile-both',
-    'runner-args': ['--src-dest', '--src-config', '--dest-config'],
-    'baksnapper-args': [],
-    'configfile': true,
-    'suite': ['configfile', 'src-dest'],
+    'name': 'backup-all-with-right-parent',
+    'runner-args': [
+      '--sender', '64,65,76,83,91,92,93',
+      '--receiver', '64,66:p=64,76:p=66,83:p=76,91:p=83,92:p=83',
+      '--expected', '64,65:p=64,66:p=64,76:p=66,83:p=76,91:p=83,92:p=83,93:p=92',
+    ],
+    'baksnapper-args': [
+      baksnapper[0].full_path(),
+      '--daemon', baksnapperd[0].full_path(),
+      '--all',
+    ],
+    'configfile': 'all',
+    'configfile-baksnapper-args': [],
+    'suite': ['backup'],
   },
 ]
-  foreach test_entry: [
+  foreach conf: [
     {
-      'name': 'default',
-      'runner-args': [
-        '--sender', '1,2,3',
-        '--expected', '3',
-      ],
-      'baksnapper-args': [
-        baksnapper[0].full_path(),
-        '--daemon', baksnapperd[0].full_path(),
-      ],
-      'configfile': 'default',
-      'configfile-baksnapper-args': [],
-      'suite': ['backup'],
+      'suffix': '-config',
+      'runner-args': [],
+      'baksnapper-args': ['--config', 'root'],
+      'configfile': false,
+      'suite': ['config'],
     },
     {
-      'name': 'latest',
-      'runner-args': [
-        '--sender', '1,2,3',
-        '--expected', '3',
-        '--expected-latest', '3',
-      ],
-      'baksnapper-args': [
-        baksnapper[0].full_path(),
-        '--daemon', baksnapperd[0].full_path(),
-        '--link',
-      ],
-      'configfile': 'latest',
-      'configfile-baksnapper-args': [],
-      'suite': ['latest'],
+      'suffix': '-src-dest',
+      'runner-args': ['--src-dest'],
+      'baksnapper-args': [],
+      'configfile': false,
+      'suite': ['src-dest'],
     },
     {
-      'name': 'prune',
-      'runner-args': [
-        '--sender', '1,2,3,6,7,8',
-        '--receiver', '1,2,3,4,5,6',
-        '--expected', '1,2,3,6,8:p=6',
-      ],
-      'baksnapper-args': [
-        baksnapper[0].full_path(),
-        '--daemon', baksnapperd[0].full_path(),
-        '--prune',
-      ],
-      'configfile': 'prune',
-      'configfile-baksnapper-args': [],
-      'suite': ['prune'],
+      'suffix': '-configfile',
+      'runner-args': [],
+      'baksnapper-args': [],
+      'configfile': true,
+      'suite': ['configfile'],
     },
     {
-      'name': 'backup-2',
-      'runner-args': [
-        '--sender', '1,2,3',
-        '--expected', '2',
-      ],
-      'baksnapper-args': [
-        baksnapper[0].full_path(),
-        '--daemon', baksnapperd[0].full_path(),
-        '--snapshot', '2',
-      ],
-      'configfile': 'default',
-      'configfile-baksnapper-args': [],
-      'suite': ['backup'],
+      'suffix': '-configfile-path',
+      'runner-args': ['--path-config'],
+      'baksnapper-args': [],
+      'configfile': true,
+      'suite': ['configfile', 'config'],
     },
     {
-      'name': 'delete-1',
-      'runner-args': [
-        '--sender', '1,2,3',
-        '--receiver', '1,2,3',
-        '--expected', '2,3',
-      ],
-      'baksnapper-args': [
-        baksnapper[0].full_path(),
-        '--daemon', baksnapperd[0].full_path(),
-        '--delete', '1',
-      ],
-      'configfile': 'default',
-      'configfile-baksnapper-args': [],
-      'suite': ['delete'],
+      'suffix': '-configfile-src-dest',
+      'runner-args': ['--src-dest'],
+      'baksnapper-args': [],
+      'configfile': true,
+      'suite': ['configfile', 'src-dest'],
     },
     {
-      'name': 'delete-1,3',
-      'runner-args': [
-        '--sender', '1,2,3',
-        '--receiver', '1,2,3',
-        '--expected', '2',
-      ],
-      'baksnapper-args': [
-        baksnapper[0].full_path(),
-        '--daemon', baksnapperd[0].full_path(),
-        '--delete', '1,3',
-      ],
-      'configfile': 'default',
-      'configfile-baksnapper-args': [],
-      'suite': ['delete'],
+      'suffix': '-configfile-src',
+      'runner-args': ['--src-dest', '--src-config'],
+      'baksnapper-args': [],
+      'configfile': true,
+      'suite': ['configfile', 'src-dest'],
     },
     {
-      'name': 'backup-with-right-parent',
-      'runner-args': [
-        '--sender', '64,65,76,83,91,92,93',
-        '--receiver', '64,66:p=64,76:p=66,83:p=76,91:p=83,92:p=83',
-        '--expected', '64,66:p=64,76:p=66,83:p=76,91:p=83,92:p=83,93:p=92',
-      ],
-      'baksnapper-args': [
-        baksnapper[0].full_path(),
-        '--daemon', baksnapperd[0].full_path(),
-      ],
-      'configfile': 'default',
-      'configfile-baksnapper-args': [],
-      'suite': ['backup'],
+      'suffix': '-configfile-dest',
+      'runner-args': ['--src-dest', '--dest-config'],
+      'baksnapper-args': [],
+      'configfile': true,
+      'suite': ['configfile', 'src-dest'],
     },
-    # https://github.com/plattfot/baksnapper/issues/27
     {
-      'name': 'backup-all-with-right-parent',
-      'runner-args': [
-        '--sender', '64,65,76,83,91,92,93',
-        '--receiver', '64,66:p=64,76:p=66,83:p=76,91:p=83,92:p=83',
-        '--expected', '64,65:p=64,66:p=64,76:p=66,83:p=76,91:p=83,92:p=83,93:p=92',
-      ],
-      'baksnapper-args': [
-        baksnapper[0].full_path(),
-        '--daemon', baksnapperd[0].full_path(),
-        '--all',
-      ],
-      'configfile': 'all',
-      'configfile-baksnapper-args': [],
-      'suite': ['backup'],
-    }
+      'suffix': '-configfile-both',
+      'runner-args': ['--src-dest', '--src-config', '--dest-config'],
+      'baksnapper-args': [],
+      'configfile': true,
+      'suite': ['configfile', 'src-dest'],
+    },
   ]
     foreach ssh: [
       {
@@ -360,6 +360,7 @@ foreach conf: [
           baksnapper_args += test_entry['configfile-baksnapper-args']
           test_depends += [test_config]
         endif
+
         test(
           test_entry['name']+conf['suffix']+ssh['suffix']+ssh_key['suffix'],
           runner,
@@ -399,44 +400,3 @@ test(
   ],
   should_fail: true,
 )
-
-test(
-  'denotebak',
-  runner,
-  env: test_env,
-  args: [
-    '--sender', ','.join([
-      '20251023T130000:t=dailies',
-      '20251023T180000:t=dailies',
-      '20251024T090000:t=dailies',
-      '20251024T130000:t=dailies',
-      '20251024T180000:t=dailies',
-      '20251025T120000',
-      '20251025T130000:t=dailies',
-      '20251025T140000:t=hourly',
-      '20251025T150000:t=hourly',
-      '20251025T160000:t=hourly']),
-    '--expected', ','.join([
-      '20251023T130000',
-      '20251023T180000:p=20251023T130000',
-      '20251024T090000:p=20251023T180000',
-      '20251024T130000:p=20251024T090000',
-      '20251024T180000:p=20251024T130000',
-      '20251025T120000:p=20251024T180000',
-      '20251025T130000:p=20251025T120000',
-      '20251025T140000:p=20251025T130000',
-      '20251025T150000:p=20251025T140000',
-      '20251025T160000:p=20251025T150000']),
-    '--type', 'denotebak',
-    '--src-dest',
-    '--',
-    baksnapper[0].full_path(),
-    '--daemon', baksnapperd_denotebak[0].full_path(),
-    '--all',
-  ],
-  depends: [
-    baksnapper,
-    baksnapperd_denotebak,
-  ],
-  suite: 'backup',
-)

From 9e88ba032332be44a9105e849c6493d787d3f954 Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Wed, 12 Nov 2025 22:07:48 -0800
Subject: [PATCH 16/22] test: Move `baksnapperd` dependency to `test_entry`
 [#45]

As DeNotebak tests will be dependent on the `baksnapperd_denotebak`
backend.  Moving this up to the `test_entry` to make it possible to
switch and get proper dependency tracking.
---
 meson.build | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/meson.build b/meson.build
index 2af34ce..9d7ef6c 100644
--- a/meson.build
+++ b/meson.build
@@ -131,6 +131,7 @@ foreach test_entry: [
     'configfile': 'default',
     'configfile-baksnapper-args': [],
     'suite': ['backup'],
+    'depends': [baksnapperd],
   },
   {
     'name': 'latest',
@@ -147,6 +148,7 @@ foreach test_entry: [
     'configfile': 'latest',
     'configfile-baksnapper-args': [],
     'suite': ['latest'],
+    'depends': [baksnapperd],
   },
   {
     'name': 'prune',
@@ -163,6 +165,7 @@ foreach test_entry: [
     'configfile': 'prune',
     'configfile-baksnapper-args': [],
     'suite': ['prune'],
+    'depends': [baksnapperd],
   },
   {
     'name': 'backup-2',
@@ -178,6 +181,7 @@ foreach test_entry: [
     'configfile': 'default',
     'configfile-baksnapper-args': [],
     'suite': ['backup'],
+    'depends': [baksnapperd],
   },
   {
     'name': 'delete-1',
@@ -194,6 +198,7 @@ foreach test_entry: [
     'configfile': 'default',
     'configfile-baksnapper-args': [],
     'suite': ['delete'],
+    'depends': [baksnapperd],
   },
   {
     'name': 'delete-1,3',
@@ -210,6 +215,7 @@ foreach test_entry: [
     'configfile': 'default',
     'configfile-baksnapper-args': [],
     'suite': ['delete'],
+    'depends': [baksnapperd],
   },
   {
     'name': 'backup-with-right-parent',
@@ -225,6 +231,7 @@ foreach test_entry: [
     'configfile': 'default',
     'configfile-baksnapper-args': [],
     'suite': ['backup'],
+    'depends': [baksnapperd],
   },
   # https://github.com/plattfot/baksnapper/issues/27
   {
@@ -242,6 +249,7 @@ foreach test_entry: [
     'configfile': 'all',
     'configfile-baksnapper-args': [],
     'suite': ['backup'],
+    'depends': [baksnapperd],
   },
 ]
   foreach conf: [
@@ -372,8 +380,7 @@ foreach test_entry: [
                 ssh_key['args'] + baksnapper_args,
           depends: [
             baksnapper,
-            baksnapperd,
-          ] + test_depends,
+          ] + test_entry['depends'] + test_depends,
           suite: conf['suite'] + test_entry['suite'],
         )
       endforeach

From c64ca307b5d81e0bd4a42962d248bd5e04a0bdc4 Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Wed, 12 Nov 2025 22:10:37 -0800
Subject: [PATCH 17/22] test: Move `env` to `test_entry` [#45]

Same reason as `depends`.
---
 meson.build | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/meson.build b/meson.build
index 9d7ef6c..cb6e532 100644
--- a/meson.build
+++ b/meson.build
@@ -132,6 +132,7 @@ foreach test_entry: [
     'configfile-baksnapper-args': [],
     'suite': ['backup'],
     'depends': [baksnapperd],
+    'env': test_env,
   },
   {
     'name': 'latest',
@@ -149,6 +150,7 @@ foreach test_entry: [
     'configfile-baksnapper-args': [],
     'suite': ['latest'],
     'depends': [baksnapperd],
+    'env': test_env,
   },
   {
     'name': 'prune',
@@ -166,6 +168,7 @@ foreach test_entry: [
     'configfile-baksnapper-args': [],
     'suite': ['prune'],
     'depends': [baksnapperd],
+    'env': test_env,
   },
   {
     'name': 'backup-2',
@@ -182,6 +185,7 @@ foreach test_entry: [
     'configfile-baksnapper-args': [],
     'suite': ['backup'],
     'depends': [baksnapperd],
+    'env': test_env,
   },
   {
     'name': 'delete-1',
@@ -199,6 +203,7 @@ foreach test_entry: [
     'configfile-baksnapper-args': [],
     'suite': ['delete'],
     'depends': [baksnapperd],
+    'env': test_env,
   },
   {
     'name': 'delete-1,3',
@@ -216,6 +221,7 @@ foreach test_entry: [
     'configfile-baksnapper-args': [],
     'suite': ['delete'],
     'depends': [baksnapperd],
+    'env': test_env,
   },
   {
     'name': 'backup-with-right-parent',
@@ -232,6 +238,7 @@ foreach test_entry: [
     'configfile-baksnapper-args': [],
     'suite': ['backup'],
     'depends': [baksnapperd],
+    'env': test_env,
   },
   # https://github.com/plattfot/baksnapper/issues/27
   {
@@ -250,6 +257,7 @@ foreach test_entry: [
     'configfile-baksnapper-args': [],
     'suite': ['backup'],
     'depends': [baksnapperd],
+    'env': test_env,
   },
 ]
   foreach conf: [
@@ -372,7 +380,7 @@ foreach test_entry: [
         test(
           test_entry['name']+conf['suffix']+ssh['suffix']+ssh_key['suffix'],
           runner,
-          env: test_env,
+          env: test_entry['env'],
           args: test_entry['runner-args'] + conf['runner-args'] +
                 ssh['args'] + runner_args +
                 ['--'] +

From ae5113f825e507b79f4c4ac187c82636eefe1a42 Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Wed, 12 Nov 2025 22:11:16 -0800
Subject: [PATCH 18/22] test: Add test configurations for DeNotebak [#45]

---
 meson.build | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/meson.build b/meson.build
index cb6e532..8fdc742 100644
--- a/meson.build
+++ b/meson.build
@@ -116,6 +116,27 @@ test_configuration = {
     'ALL': 'YES',
     'VERBOSE': 'NO',
   },
+  'denotebak-default': {
+    'DAEMON': baksnapperd_denotebak[0].full_path(),
+  },
+  'denotebak-latest': {
+    'DAEMON': baksnapperd_denotebak[0].full_path(),
+    'PRUNE': 'NO',
+    'ALL': 'NO',
+    'VERBOSE': 'NO',
+    'LINK': 'YES',
+  },
+  'denotebak-prune': {
+    'DAEMON': baksnapperd_denotebak[0].full_path(),
+    'PRUNE': 'YES',
+    'ALL': 'NO',
+    'VERBOSE': 'NO',
+  },
+  'denotebak-all': {
+    'DAEMON': baksnapperd_denotebak[0].full_path(),
+    'ALL': 'YES',
+    'VERBOSE': 'NO',
+  },
 }
 foreach test_entry: [
   {

From ea8ab6ad818857ec5f946c99490ed595ee93aff7 Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Wed, 12 Nov 2025 22:11:49 -0800
Subject: [PATCH 19/22] test: Skip `--config` tests for DeNotebak tests [#45]

As they are not supported with --config.
---
 meson.build | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/meson.build b/meson.build
index 8fdc742..5b003b8 100644
--- a/meson.build
+++ b/meson.build
@@ -398,6 +398,11 @@ foreach test_entry: [
           test_depends += [test_config]
         endif
 
+        # The DeNotebak backend does not support --config
+        if 'denotebak' in test_entry['suite'] and 'src-dest' not in conf['suite']
+          continue
+        endif
+
         test(
           test_entry['name']+conf['suffix']+ssh['suffix']+ssh_key['suffix'],
           runner,

From d99eb835e277f9be54ee2661f69bd857f23612b4 Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Wed, 12 Nov 2025 22:13:36 -0800
Subject: [PATCH 20/22] test: Add `denotebak_test_env` [#45]

Which just changes the ssh baksnapperd backend to the denotebak end.
---
 meson.build | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/meson.build b/meson.build
index 5b003b8..d474d3e 100644
--- a/meson.build
+++ b/meson.build
@@ -92,6 +92,9 @@ test_env.set('MOCK_SSH_CONNECTION', '0')
 test_env.set('MOCK_SSH_KEY', 'foo.key=foo.example.com:bar.key=bar.example.com')
 test_env.set('MOCK_SSH_BAKSNAPPERD', baksnapperd[0].full_path())
 
+denotebak_test_env = test_env
+denotebak_test_env.set('MOCK_SSH_BAKSNAPPERD', baksnapperd_denotebak[0].full_path())
+
 runner = find_program('./tests/runner.scm')
 
 test_configuration = {

From 2841cf3ceb07208f5286466dfd90dc7d6ed88bdc Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Wed, 12 Nov 2025 22:12:54 -0800
Subject: [PATCH 21/22] test: Add DeNotebak tests to `test_entry` [#45]

---
 meson.build | 245 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 245 insertions(+)

diff --git a/meson.build b/meson.build
index d474d3e..1e46ca3 100644
--- a/meson.build
+++ b/meson.build
@@ -283,6 +283,251 @@ foreach test_entry: [
     'depends': [baksnapperd],
     'env': test_env,
   },
+  # DeNotebak
+  {
+    'name': 'denotebak-default',
+    'runner-args': [
+      '--sender', ','.join([
+        '20251023T130000:t=dailies',
+        '20251025T120000',
+        '20251025T160000:t=hourly']),
+      '--expected', ','.join([
+        '20251025T160000']),
+      '--type', 'denotebak',
+    ],
+    'baksnapper-args': [
+      baksnapper[0].full_path(),
+      '--daemon', baksnapperd_denotebak[0].full_path(),
+    ],
+    'configfile': 'denotebak-default',
+    'configfile-baksnapper-args': [],
+    'suite': ['denotebak', 'backup'],
+    'depends': [baksnapperd_denotebak],
+    'env': denotebak_test_env,
+  },
+  {
+    'name': 'denotebak-latest',
+    'runner-args': [
+      '--sender', ','.join([
+        '20251023T130000:t=dailies',
+        '20251025T120000',
+        '20251025T160000:t=hourly']),
+      '--expected', ','.join([
+        '20251025T160000']),
+      '--expected-latest', '20251025T160000',
+      '--type', 'denotebak',
+    ],
+    'baksnapper-args': [
+      baksnapper[0].full_path(),
+      '--daemon', baksnapperd_denotebak[0].full_path(),
+      '--link',
+    ],
+    'configfile': 'denotebak-latest',
+    'configfile-baksnapper-args': [],
+    'suite': ['denotebak', 'latest'],
+    'depends': [baksnapperd_denotebak],
+    'env': denotebak_test_env,
+  },
+  {
+    'name': 'denotebak-prune',
+    'runner-args': [
+      '--sender', ','.join([
+        '20251023T130000:t=dailies',
+        '20251025T120000',
+        '20251025T130000:t=dailies',
+        '20251025T140000:t=hourly',
+        '20251025T150000:t=hourly',
+        '20251025T160000:t=hourly']),
+      '--receiver', ','.join([
+        '20251023T130000',
+        '20251023T180000',
+        '20251024T090000',
+        '20251024T130000',
+        '20251024T180000',
+        '20251025T120000',
+        '20251025T130000']),
+      '--expected', ','.join([
+        '20251023T130000',
+        '20251025T120000',
+        '20251025T130000',
+        '20251025T160000:p=20251025T130000']),
+      '--type', 'denotebak',
+    ],
+    'baksnapper-args': [
+      baksnapper[0].full_path(),
+      '--daemon', baksnapperd_denotebak[0].full_path(),
+      '--prune',
+    ],
+    'configfile': 'denotebak-prune',
+    'configfile-baksnapper-args': [],
+    'suite': ['denotebak', 'prune'],
+    'depends': [baksnapperd_denotebak],
+    'env': denotebak_test_env,
+  },
+  {
+    'name': 'denotebak-backup-20251025T150000',
+    'runner-args': [
+      '--sender', ','.join([
+        '20251025T140000:t=hourly',
+        '20251025T150000:t=hourly',
+        '20251025T160000:t=hourly']),
+      '--expected', ','.join([
+        '20251025T150000']),
+      '--type', 'denotebak',
+    ],
+    'baksnapper-args': [
+      baksnapper[0].full_path(),
+      '--daemon', baksnapperd_denotebak[0].full_path(),
+      '--snapshot', '20251025T150000',
+    ],
+    'configfile': 'denotebak-default',
+    'configfile-baksnapper-args': [],
+    'suite': ['denotebak', 'backup'],
+    'depends': [baksnapperd_denotebak],
+    'env': denotebak_test_env,
+  },
+  {
+    'name': 'denotebak-delete-20251025T140000',
+    'runner-args': [
+      '--sender', ','.join([
+        '20251025T140000:t=hourly',
+        '20251025T150000:t=hourly',
+        '20251025T160000:t=hourly']),
+      '--receiver', ','.join([
+        '20251025T140000',
+        '20251025T150000',
+        '20251025T160000']),
+      '--expected', ','.join([
+        '20251025T150000',
+        '20251025T160000']),
+      '--type', 'denotebak',
+    ],
+    'baksnapper-args': [
+      baksnapper[0].full_path(),
+      '--daemon', baksnapperd_denotebak[0].full_path(),
+      '--delete', '20251025T140000',
+    ],
+    'configfile': 'denotebak-default',
+    'configfile-baksnapper-args': [],
+    'suite': ['denotebak', 'delete'],
+    'depends': [baksnapperd_denotebak],
+    'env': denotebak_test_env,
+  },
+  {
+    'name': 'denotebak-delete-20251025T140000,20251025T160000',
+    'runner-args': [
+      '--sender', ','.join([
+        '20251025T140000:t=hourly',
+        '20251025T150000:t=hourly',
+        '20251025T160000:t=hourly']),
+      '--receiver', ','.join([
+        '20251025T140000:t=hourly',
+        '20251025T150000',
+        '20251025T160000']),
+      '--expected', ','.join([
+        '20251025T150000']),
+      '--type', 'denotebak',
+    ],
+    'baksnapper-args': [
+      baksnapper[0].full_path(),
+      '--daemon', baksnapperd_denotebak[0].full_path(),
+      '--delete', '20251025T140000,20251025T160000',
+    ],
+    'configfile': 'denotebak-default',
+    'configfile-baksnapper-args': [],
+    'suite': ['denotebak', 'delete'],
+    'depends': [baksnapperd_denotebak],
+    'env': denotebak_test_env,
+  },
+  {
+    'name': 'denotebak-backup-with-right-parent',
+    'runner-args': [
+      '--sender', ','.join([
+        '20251023T130000:t=dailies',
+        '20251023T180000:t=dailies',
+        '20251024T090000:t=dailies',
+        '20251024T130000:t=dailies',
+        '20251024T180000:t=dailies',
+        '20251025T120000',
+        '20251025T130000:t=dailies',
+        '20251025T140000:t=hourly',
+        '20251025T150000:t=hourly',
+        '20251025T160000:t=hourly']),
+      '--receiver', ','.join([
+        '20251023T130000',
+        '20251023T180000:p=20251023T130000',
+        '20251024T090000:p=20251023T180000',
+        '20251024T130000:p=20251024T090000',
+        '20251024T180000:p=20251024T130000',
+        '20251025T120000:p=20251024T180000',
+        '20251025T130000:p=20251025T120000']),
+      '--expected', ','.join([
+        '20251023T130000',
+        '20251023T180000:p=20251023T130000',
+        '20251024T090000:p=20251023T180000',
+        '20251024T130000:p=20251024T090000',
+        '20251024T180000:p=20251024T130000',
+        '20251025T120000:p=20251024T180000',
+        '20251025T130000:p=20251025T120000',
+        '20251025T160000:p=20251025T130000']),
+      '--type', 'denotebak',
+    ],
+    'baksnapper-args': [
+      baksnapper[0].full_path(),
+      '--daemon', baksnapperd_denotebak[0].full_path(),
+    ],
+    'configfile': 'denotebak-default',
+    'configfile-baksnapper-args': [],
+    'suite': ['denotebak', 'backup'],
+    'depends': [baksnapperd_denotebak],
+    'env': denotebak_test_env,
+  },
+  {
+    'name': 'denotebak-backup-all-with-right-parent',
+    'runner-args': [
+      '--sender', ','.join([
+        '20251023T130000:t=dailies',
+        '20251023T180000:t=dailies',
+        '20251024T090000:t=dailies',
+        '20251024T130000:t=dailies',
+        '20251024T180000:t=dailies',
+        '20251025T120000',
+        '20251025T130000:t=dailies',
+        '20251025T140000:t=hourly',
+        '20251025T150000:t=hourly',
+        '20251025T160000:t=hourly']),
+      '--receiver', ','.join([
+        '20251023T130000',
+        '20251023T180000:p=20251023T130000',
+        '20251024T090000:p=20251023T180000',
+        '20251024T130000:p=20251024T090000',
+        '20251024T180000:p=20251024T130000',
+        '20251025T120000:p=20251024T180000',
+        '20251025T130000:p=20251025T120000']),
+      '--expected', ','.join([
+        '20251023T130000',
+        '20251023T180000:p=20251023T130000',
+        '20251024T090000:p=20251023T180000',
+        '20251024T130000:p=20251024T090000',
+        '20251024T180000:p=20251024T130000',
+        '20251025T120000:p=20251024T180000',
+        '20251025T130000:p=20251025T120000',
+        '20251025T140000:p=20251025T130000',
+        '20251025T150000:p=20251025T140000',
+        '20251025T160000:p=20251025T150000']),
+      '--type', 'denotebak',
+    ],
+    'baksnapper-args': [
+      baksnapper[0].full_path(),
+      '--daemon', baksnapperd_denotebak[0].full_path(),
+      '--all',
+    ],
+    'configfile': 'denotebak-all',
+    'configfile-baksnapper-args': [],
+    'suite': ['denotebak', 'backup'],
+    'depends': [baksnapperd_denotebak],
+    'env': denotebak_test_env,
+  },
 ]
   foreach conf: [
     {

From b131231b8bb13d6216f195ef19e5bcd730701b20 Mon Sep 17 00:00:00 2001
From: Fredrik Salomonsson <plattfot@posteo.net>
Date: Sun, 16 Nov 2025 17:01:36 -0800
Subject: [PATCH 22/22] changelog: add DeNotebak backend

---
 CHANGELOG.d/20251116T170044--add-denotebak-backend__added.md | 4 ++++
 1 file changed, 4 insertions(+)
 create mode 100644 CHANGELOG.d/20251116T170044--add-denotebak-backend__added.md

diff --git a/CHANGELOG.d/20251116T170044--add-denotebak-backend__added.md b/CHANGELOG.d/20251116T170044--add-denotebak-backend__added.md
new file mode 100644
index 0000000..23b768d
--- /dev/null
+++ b/CHANGELOG.d/20251116T170044--add-denotebak-backend__added.md
@@ -0,0 +1,4 @@
+<!-- SPDX-FileCopyrightText: 2025 Fredrik Salomonsson <plattfot@posteo.net> -->
+<!-- SPDX-License-Identifier: GPL-3.0-or-later -->
+### Added
+- [DeNotebak](https://sr.ht/~plattfot/DeNotebak/) backend support. [#45](https://github.com/plattfot/baksnapper/issues/45)