Fix Error check and error message style

misc/build.func

@@ -363,7 +363,7 @@ validate_hostname() {
 
   # Split by dots and validate each label
   local IFS='.'
-  read -ra labels <<< "$hostname"
+  read -ra labels <<<"$hostname"
   for label in "${labels[@]}"; do
     # Each label: 1-63 chars, alphanumeric, hyphens allowed (not at start/end)
     if [[ -z "$label" ]] || [[ ${#label} -gt 63 ]]; then
@@ -467,7 +467,7 @@ validate_ipv6_address() {
   # Check that no segment exceeds 4 hex chars
   local IFS=':'
   local -a segments
-  read -ra segments <<< "$addr"
+  read -ra segments <<<"$addr"
   for seg in "${segments[@]}"; do
     if [[ ${#seg} -gt 4 ]]; then
       return 1
@@ -517,14 +517,14 @@ validate_gateway_in_subnet() {
 
   # Convert IPs to integers
   local IFS='.'
-  read -r i1 i2 i3 i4 <<< "$ip"
-  read -r g1 g2 g3 g4 <<< "$gateway"
+  read -r i1 i2 i3 i4 <<<"$ip"
+  read -r g1 g2 g3 g4 <<<"$gateway"
 
-  local ip_int=$(( (i1 << 24) + (i2 << 16) + (i3 << 8) + i4 ))
-  local gw_int=$(( (g1 << 24) + (g2 << 16) + (g3 << 8) + g4 ))
+  local ip_int=$(((i1 << 24) + (i2 << 16) + (i3 << 8) + i4))
+  local gw_int=$(((g1 << 24) + (g2 << 16) + (g3 << 8) + g4))
 
   # Check if both are in same network
-  if (( (ip_int & mask) != (gw_int & mask) )); then
+  if (((ip_int & mask) != (gw_int & mask))); then
     return 1
   fi
 
@@ -1152,7 +1152,7 @@ load_vars_file() {
             fi
           fi
           ;;
-          var_fuse|var_tun|var_gpu|var_ssh|var_verbose|var_protection)
+        var_fuse | var_tun | var_gpu | var_ssh | var_verbose | var_protection)
           if [[ "$var_val" != "yes" && "$var_val" != "no" ]]; then
             msg_warn "Invalid boolean '$var_val' for $var_key in $file (must be yes/no), ignoring"
             continue
@@ -3086,21 +3086,29 @@ check_container_resources() {
 # ------------------------------------------------------------------------------
 # check_container_storage()
 #
-# - Checks /boot partition usage
+# - Checks root (/) partition usage
 # - Warns if usage >80% and asks user confirmation before proceeding
 # ------------------------------------------------------------------------------
 check_container_storage() {
-  total_size=$(df /boot --output=size | tail -n 1)
-  local used_size=$(df /boot --output=used | tail -n 1)
-  usage=$((100 * used_size / total_size))
-  if ((usage > 80)); then
-    echo -e "${INFO}${HOLD} ${YWB}Warning: Storage is dangerously low (${usage}%).${CL}"
-    echo -ne "Continue anyway? <y/N>  "
-    read -r prompt
-    if [[ ! ${prompt,,} =~ ^(y|yes)$ ]]; then
-      echo -e "${CROSS}${HOLD}${YWB}Exiting based on user input.${CL}"
+  usage=$(df / -P | awk 'NR==2 {print $5}' | tr -d '%')
+
+  if [ -z "$usage" ] || [ "$usage" -lt 0 ]; then
+    echo -e "${CROSS}${HOLD}${RD}Error: Failed to check disk usage.${CL}"
     exit 1
   fi
+
+  if [ "$usage" -gt 80 ]; then
+    echo -e "${INFO}${HOLD}${YWB}Warning: Storage is dangerously low (${usage}%).${CL}"
+    printf "Continue anyway? <y/N>  "
+    read -r prompt
+
+    case "$prompt" in
+    [yY][eE][sS] | [yY]) ;;
+    *)
+      echo -e "${CROSS}${HOLD}${YWB}Exiting based on user input.${CL}"
+      exit 1
+      ;;
+    esac
   fi
 }