Add HDD device previews and root guards

lib/common.sh

@@ -90,3 +90,24 @@ common::require_cmd() {
         common::die "required command '${cmd}' not found on PATH"
     fi
 }
+
+# common::show_block_devices prints available block devices and highlights
+# the selected device when output is going to a terminal.
+common::show_block_devices() {
+    local selected_device="$1"
+    local color=0
+
+    if [[ -t 1 && -z "${NO_COLOR:-}" ]]; then
+        color=1
+    fi
+
+    common::log "Available block devices and mount points (selected device highlighted):"
+    lsblk --list --paths --output PATH,SIZE,TYPE,FSTYPE,MOUNTPOINTS \
+        | awk -v selected="$selected_device" -v color="$color" '
+            NR > 1 && $1 == selected && color {
+                printf "\033[31m%s\033[0m\n", $0
+                next
+            }
+            { print }
+        '
+}