feat(backup): add audited backup listing and restoration

tests/mocks/bin/flock

@@ -5,11 +5,44 @@ command_name=${0##*/}
 printf '%q' "$command_name" >>"$TEST_MOCK_LOG"
 for argument in "$@"; do printf ' %q' "$argument" >>"$TEST_MOCK_LOG"; done
 printf '\n' >>"$TEST_MOCK_LOG"
-[[ $# == 2 && $1 == -n && $2 =~ ^[0-9]+$ ]] || exit 99
 if [[ -n ${MOCK_FLOCK_CHANGE_TO:-} && -z ${MOCK_FLOCK_CHANGED_MARKER:-} && -f $MOCK_FLOCK_CHANGE_TO && -n ${WG_MANAGER_CONFIG:-} ]]; then
   cp -- "$MOCK_FLOCK_CHANGE_TO" "$WG_MANAGER_CONFIG"
   export MOCK_FLOCK_CHANGED_MARKER=1
 fi
-if [[ ${MOCK_FLOCK_BUSY:-0} == 1 ]]; then exit 1; fi
-if [[ ${MOCK_FLOCK_FAIL:-0} == 1 ]]; then exit 97; fi
-exit 0
+if [[ $# == 2 && $1 == -n && $2 =~ ^[0-9]+$ ]]; then
+  [[ ${MOCK_FLOCK_BUSY:-0} == 1 ]] && exit 1
+  [[ ${MOCK_FLOCK_FAIL:-0} == 1 ]] && exit 97
+  exit 0
+fi
+if [[ $# -ge 3 && $1 == -n && $2 =~ ^[0-9]+$ && ( $3 == printf || $3 == cat ) ]]; then
+  [[ ${MOCK_FLOCK_BUSY:-0} == 1 ]] && exit 1
+  [[ ${MOCK_FLOCK_FAIL:-0} == 1 ]] && exit 97
+  shift 2
+  command "$@"
+  exit $?
+fi
+if [[ $# == 1 && $1 =~ ^[0-9]+$ || $# == 2 && $1 == -s && $2 =~ ^[0-9]+$ ]]; then
+  [[ ${MOCK_FLOCK_BUSY:-0} == 1 ]] && exit 1
+  [[ ${MOCK_FLOCK_FAIL:-0} == 1 ]] && exit 97
+  real_flock=${REAL_FLOCK:-}
+  if [[ -z $real_flock ]]; then
+    for candidate in /usr/bin/flock /bin/flock; do
+      if [[ -x $candidate ]]; then real_flock=$candidate; break; fi
+    done
+  fi
+  [[ -n $real_flock ]] || exit 98
+  exec "$real_flock" "$@"
+fi
+if [[ $# -ge 2 && ( $1 == -s || $1 != -* ) && ${1#-} =~ ^[0-9]+$ || $1 == -s && ${2:-} =~ ^[0-9]+$ ]]; then
+  [[ ${MOCK_FLOCK_BUSY:-0} == 1 ]] && exit 1
+  [[ ${MOCK_FLOCK_FAIL:-0} == 1 ]] && exit 97
+  real_flock=${REAL_FLOCK:-}
+  if [[ -z $real_flock ]]; then
+    for candidate in /usr/bin/flock /bin/flock; do
+      if [[ -x $candidate ]]; then real_flock=$candidate; break; fi
+    done
+  fi
+  [[ -n $real_flock ]] || exit 98
+  exec "$real_flock" "$@"
+fi
+exit 99