Support optimizing (shrinking) bootable partitions on images with GPT…

… partition tables (#117)

* Fix bug #116 by resizing boot partition instead of deleting and recreating it

.github/workflows/test-gpt-partition-table.yml

@@ -18,4 +18,4 @@ jobs:
           image_additional_mb: 2048
           cpu: cortex-a53
           commands: |
-            test $(df -h --output=size / | tail -n 1) = '2.8G'
+            test $(df -h --output=size / | tail -n 1) = '2.8G'

.github/workflows/test-shrink-bootable-partition.yml

@@ -0,0 +1,25 @@
+name: Test shrink_bootable_partition
+on:
+  push:
+    branches:
+      - 'main'
+      - 'releases/**'
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  optimized:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: ./ # pguyot/arm-runner-action@HEAD
+      id: shrink
+      with:
+        base_image: https://github.com/Joshua-Riek/ubuntu-rockchip/releases/download/v2.2.1/ubuntu-24.04-preinstalled-server-arm64-orangepi-5.img.xz
+        optimize_image: yes
+        commands: |
+            echo "Shrink Bootable Partition"
+    - name: Check image
+      run: |
+         parted --script ${{ steps.shrink.outputs.image }} print free | tail -n2 | head -n1 | grep -c "boot, esp"
+

cleanup_image.sh

@@ -48,6 +48,9 @@ if [[ -d "${mount}" ]]; then
     if [[ "${optimize}x" == "x" || "${optimize}x" == "yesx" ]]; then
         rootfs_partnum=${rootpartition}
         rootdev="${loopdev}p${rootfs_partnum}"
+
+        part_type=$(blkid -o value -s PTTYPE "${loopdev}")
+        echo "Image is using ${part_type} partition table"
 
         echo "Resizing root filesystem to minimal size."
         e2fsck -p -f "${rootdev}"
@@ -63,8 +66,7 @@ if [[ -d "${mount}" ]]; then
         # parted --script "${loopdev}" unit B resizepart "${rootfs_partnum}" "${rootfs_partend}"
         # Can't use resizepart for shrinking with --script (parted bug#22167) => must rm then mkpart
         if [ "$rootfs_partoldend" -gt "$rootfs_partend" ]; then
-            parted --script "${loopdev}" rm "${rootfs_partnum}"
-            parted --script "${loopdev}" unit B mkpart primary "${rootfs_partstart}" "${rootfs_partend}"
+            echo y | parted ---pretend-input-tty "${loopdev}" unit B resizepart "${rootfs_partnum}" "${rootfs_partend}"
         else
             echo "Rootfs partition not resized as it was not shrunk"
         fi
@@ -73,8 +75,17 @@ if [[ -d "${mount}" ]]; then
         if [[ "${free_space}" =~ "free" ]]; then
             initial_image_size=$(stat -L --printf="%s" "${image}")
             image_size=$(echo "${free_space}" | awk -F ":" '{print $2}' | tr -d 'B')
+            if [[ "${part_type}" == "gpt" ]]; then
+                # for GPT partition table, leave space at the end for the secondary GPT 
+                # it requires 33 sectors, which is 16896 bytes
+                image_size=$((image_size + 16896))
+            fi            
             echo "Shrinking image from ${initial_image_size} to ${image_size} bytes."
             truncate -s "${image_size}" "${image}"
+            if [[ "${part_type}" == "gpt" ]]; then
+                # use sgdisk to fix the secondary GPT after truncation 
+                sgdisk -e "${image}"
+            fi
         fi
     fi
     rmdir "${mount}" || true