Allow disk resizing

disk.sh

@@ -4,29 +4,56 @@ set -eu
 BOOT="$IMG/boot.img"
 [ ! -f "$BOOT" ] && echo "ERROR: Boot image does not exist ($BOOT)" && exit 81
 
+DATA="${IMG}/data.img"
 DISK_SIZE=$(echo "${DISK_SIZE}" | sed 's/MB/M/g;s/GB/G/g;s/TB/T/g')
 DATA_SIZE=$(numfmt --from=iec "${DISK_SIZE}")
 
-DATA="$IMG/data${DISK_SIZE}.img"
+if [ -f "${DATA}" ]; then
 
-if [ ! -f "$DATA" ]; then
+  OLD_SIZE=$(stat -c%s "${DATA}")
+
+  # Resize disk to new size if needed
+
+  if [ "$DATA_SIZE" -ne "$OLD_SIZE" ]; then
+
+    if [ "$DATA_SIZE" -gt "$OLD_SIZE" ]; then
+      echo "Resizing data disk from $OLD_SIZE to $DATA_SIZE bytes.."
+      fallocate -l "${DATA_SIZE}" "${DATA}"
+    fi
+
+    if [ "$DATA_SIZE" -lt "$OLD_SIZE" ]; then
+
+      echo "INFO: Shrinking existing disks is not supported yet!"
+      echo "INFO: Creating backup of old drive in storage folder..."
+
+      mv -f "${DATA}" "${DATA}.bak"
+
+    fi
+  fi
+fi
+
+if [ ! -f "${DATA}" ]; then
 
   # Check free diskspace
-  SPACE=$(df --output=avail -B 1 "$IMG" | tail -n 1)
+  SPACE=$(df --output=avail -B 1 "${IMG}" | tail -n 1)
 
   if (( DATA_SIZE > SPACE )); then
-    echo "ERROR: Not enough free space to create virtual disk." && exit 82
+    echo "ERROR: Not enough free space to create virtual disk." && exit 84
   fi
 
+  # Create an empty file
   if ! fallocate -l "${DATA_SIZE}" "${DATA}"; then
     rm -f "${DATA}"
-    echo "ERROR: Could not allocate file for virtual disk." && exit 82
+    echo "ERROR: Could not allocate file for virtual disk." && exit 85
+  fi
+
+  # Check if file exists
+  if [ ! -f "${DATA}" ]; then
+    echo "ERROR: Data image does not exist ($DATA)" && exit 86
   fi
 
 fi
 
-[ ! -f "$DATA" ] && echo "ERROR: Data image does not exist ($DATA)" && exit 83
-
 KVM_DISK_OPTS="\
     -drive id=cdrom0,if=none,format=raw,readonly=on,file=${BOOT} \
     -device virtio-scsi-pci,id=scsi0 \