Add/use border label feature flag

fzf 0.35 added the ability to added labels to borders - both for the
entire application window and for the preview window. This can now be
used to add a global header, present on all fzf instances. The snapshot
screen can now optionally move context text to the bottom border around
the preview window instead of being in it.

zfsbootmenu/bin/zfsbootmenu

@@ -96,6 +96,14 @@ fuzzy_default_options=(
   "--bind" "\"ctrl-alt-l:execute[ /bin/zlogtail ]${HAS_REFRESH:++refresh-preview}\""
 )
 
+if [ -n "${HAS_BORDER_LABEL}" ]; then
+  # shellcheck disable=SC2016
+  fuzzy_default_options+=(
+    "--border-label-pos=top" "--border=top"
+    "--color=border:white" "--separator=''"
+  )
+fi
+
 # shellcheck disable=SC2016,SC2086
 if [ ${loglevel:-4} -eq 7 ] ; then
   fuzzy_default_options+=(

zfsbootmenu/bin/zlogtail

@@ -1,5 +1,8 @@
 #!/bin/bash
 
+# shellcheck disable=SC1091
+source /lib/zfsbootmenu-lib.sh >/dev/null 2>&1 || exit 1
+
 [ -f "${BASE}/have_errors" ] && rm "${BASE}/have_errors"
 [ -f "${BASE}/have_warnings" ] && rm "${BASE}/have_warnings"
 
@@ -16,6 +19,14 @@ if [ -n "${HAS_DISABLED}" ]; then
   )
 fi
 
+if [ -n "${HAS_BORDER_LABEL}" ]; then
+  fuzzy_default_options+=(
+    "--border-label-pos=top" "--border=top"
+    "--border-label=\"$( global_header zlogtail )\""
+    "--color=border:white"
+  )
+fi
+
 export FZF_DEFAULT_OPTS="${fuzzy_default_options[*]}"
 
 # Try to use feature flags found on dmesg from util-linux

zfsbootmenu/install-helpers.sh

@@ -98,6 +98,13 @@ create_zbm_conf() {
     has_disabled=1
   fi
 
+  # Check if fuzzy finder supports border labels
+  # Added in fzf 0.35.0
+  local has_border_label
+  if echo "abc" | fzf -f "abc" --border-label=test --exit-0 >/dev/null 2>&1; then
+    has_border_label=1
+  fi
+
   local has_column
   if command -v column >/dev/null 2>&1 ; then
     has_column=1
@@ -113,6 +120,7 @@ create_zbm_conf() {
 	export BYTE_ORDER="${endian:-le}"
 	export HAS_REFRESH="${has_refresh}"
 	export HAS_DISABLED="${has_disabled}"
+	export HAS_BORDER_LABEL="${has_border_label}"
 	export HAS_COLUMN="${has_column}"
 	EOF
 }

zfsbootmenu/lib/zfsbootmenu-lib.sh

@@ -67,6 +67,53 @@ column_wrap() {
   echo -e "${footer//^/${pad}}"
 }
 
+# arg1: optional page to mark as active
+# prints: a header string with the active page highlighted yellow
+# returns: nothing
+
+# shellcheck disable=SC2120
+global_header() {
+  local header page tab
+
+  # Accept a parameter to explicitly set a page to be shown
+  if [ -n "${1}" ]; then
+    page="${1}"
+  else
+    # Name of the calling function
+    page="${FUNCNAME[1]}"
+  fi
+
+  # Set the entire string to one color
+  header="\\033[0;37m Boot Environments | Snapshots | Kernels | Pool Status | Logs | Help \\033[0m"
+
+  case "${page}" in
+    draw_be)
+      tab="Boot Environments"
+      ;;
+    draw_kernel)
+      tab="Kernels"
+      ;;
+    draw_snapshots|draw_diff)
+      tab="Snapshots"
+      ;;
+    draw_pool_status)
+      tab="Pool Status"
+      ;;
+    help_pager)
+      tab="Help"
+      ;;
+    zlogtail)
+      tab="Logs"
+      ;;
+    *)
+      zdebug "Called from unknown function: ${page}"
+      ;;
+  esac
+
+  # change the name of the selected tab to be yellow
+  echo -n -e "${header/${tab}/\\033[1;33m${tab}\\033[0;37m}"
+}
+
 # arg1: Path to file with detected boot environments, 1 per line
 # prints: key pressed, boot environment on successful selection
 # returns: 0 on successful selection, 1 if Esc was pressed, 130 if BE list is missing
@@ -109,7 +156,8 @@ draw_be() {
 
   if ! selected="$( ${FUZZYSEL} -0 --prompt "BE > " \
       ${expects} ${expects//alt-/ctrl-} ${expects//alt-/ctrl-alt-} \
-      --header="${header}" --preview-window="up:${PREVIEW_HEIGHT}" \
+      ${HAS_BORDER_LABEL:+--border-label="$( global_header )"} \
+      --header="${header}" --preview-window="up:${PREVIEW_HEIGHT},border-sharp" \
       --preview="/libexec/zfsbootmenu-preview {} ${BOOTFS}" < "${env}" )"; then
     return 1
   fi
@@ -156,9 +204,10 @@ draw_kernel() {
 
   if ! selected="$( HELP_SECTION=kernel-management ${FUZZYSEL} \
       --prompt "${benv} > " --tac --with-nth=2 --header="${header}" \
+      ${HAS_BORDER_LABEL:+--border-label="$( global_header )"} \
       ${expects} ${expects//alt-/ctrl-} ${expects//alt-/ctrl-alt-} \
       --preview="/libexec/zfsbootmenu-preview ${benv} ${BOOTFS}"  \
-      --preview-window="up:${PREVIEW_HEIGHT}" < "${_kernels}" )"; then
+      --preview-window="up:${PREVIEW_HEIGHT},border-sharp" < "${_kernels}" )"; then
     return 1
   fi
 
@@ -206,14 +255,28 @@ draw_snapshots() {
 
   zdebug "snapshots: ${snapshots[*]}"
 
-  if ! selected="$( HELP_SECTION=snapshot-management ${FUZZYSEL} \
+  # when defined this controls passing an additional parameter to zfsbootmenu-preview
+  # as well as extending the preview window height by 1
+  # when undefined, it triggers added 0 to the window height, leaving it as-is
+
+  local LEGACY_CONTEXT
+  if [ -z "${HAS_BORDER_LABEL}" ]; then
+    LEGACY_CONTEXT=1
+  fi
+
+  if ! selected="$(\
+      HELP_SECTION=snapshot-management ${FUZZYSEL} \
         --prompt "Snapshot > " --header="${header}" --tac --multi 2 \
+        ${HAS_BORDER_LABEL:+--border-label="$( global_header )"} \
         ${expects} ${expects//alt-/ctrl-} ${expects//alt-/ctrl-alt-} \
         --bind='alt-d:execute[ /libexec/zfunc draw_diff {+} ]' \
         --bind='ctrl-d:execute[ /libexec/zfunc draw_diff {+} ]' \
         --bind='ctrl-alt-d:execute[ /libexec/zfunc draw_diff {+} ]' \
-        --preview="/libexec/zfsbootmenu-preview ${benv} ${BOOTFS} '${context}'" \
-        --preview-window="up:$(( PREVIEW_HEIGHT + 1 ))" <<<"${snapshots}" )"; then
+        ${HAS_BORDER_LABEL:+--preview-label-pos=bottom} \
+        ${HAS_BORDER_LABEL:+--preview-label="$( colorize orange " ${context} " )"} \
+        --preview="/libexec/zfsbootmenu-preview ${benv} ${BOOTFS} ${LEGACY_CONTEXT:+\"${context}\"}" \
+        --preview-window="up:$(( PREVIEW_HEIGHT + ${LEGACY_CONTEXT:-0} )),border-sharp" <<<"${snapshots}" )"
+  then
     return 1
   fi
 
@@ -291,8 +354,9 @@ draw_diff() {
   line_two="${left_pad}$( colorize green "+++${diff_target}" )"
 
   sed "s,${mnt},," <&3 | HELP_SECTION=diff-viewer ${FUZZYSEL} --prompt "> " \
+    ${HAS_BORDER_LABEL:+--border-label="$( global_header )"} \
     --preview="echo -e '${line_one}\n${line_two}'" --no-sort \
-    --preview-window="up:${PREVIEW_HEIGHT}"
+    --preview-window="up:${PREVIEW_HEIGHT},border-sharp"
 
   [ -n "${zfs_diff_PID}" ] && kill "${zfs_diff_PID}"
 
@@ -322,7 +386,8 @@ draw_pool_status() {
   if ! selected="$( zpool list -H -o name |
       HELP_SECTION=zpool-health ${FUZZYSEL} \
       --prompt "Pool > " --tac --expect=alt-r,ctrl-r,ctrl-alt-r \
-      --preview-window="right:${psize}" \
+      ${HAS_BORDER_LABEL:+--border-label="$( global_header )"} \
+      --preview-window="right:${psize},border-sharp" \
       --preview="zpool status -v {}" --header="${header}" )"; then
     return 1
   fi

zfsbootmenu/libexec/zfsbootmenu-help

@@ -42,8 +42,9 @@ help_pager() {
     --with-nth=2.. \
     --bind pgup:preview-up,pgdn:preview-down \
     --preview="$0 -s {1}" \
-    --preview-window="right:${PREVIEW_SIZE}:wrap" \
+    --preview-window="right:${PREVIEW_SIZE}:wrap,border-sharp" \
     --header="${header}" \
+    --border=top --border-label="$( global_header )" \
     --tac --inline-info --ansi --layout="reverse-list"
 }