build_library: Add generation of disk space usage

This could replace an ad-hoc calculations we do in package-diff.

build_library/build_image_util.sh

@@ -274,6 +274,30 @@ write_contents_with_technical_details() {
     popd >/dev/null
 }
 
+# Generate a report like the following:
+#
+# File    Size  Used Avail Use% Type
+# /boot   127M   62M   65M  50% vfat
+# /usr    983M  721M  212M  78% ext2
+# /       6,0G   13M  5,6G   1% ext4
+# SUM     7,0G  796M  5,9G  12% -
+write_disk_space_usage() {
+    info "Writing ${2##*/}"
+    pushd "${1}" >/dev/null
+    # The sed's first command turns './<path>' into '/<path> ', second
+    # command replaces '- ' with 'SUM' for the total row. All this to
+    # keep the numbers neatly aligned in columns.
+    sudo df \
+         --human-readable \
+         --total \
+         --output='file,size,used,avail,pcent,fstype' \
+         ./boot ./usr ./ | \
+        sed \
+            -e 's#^\.\(/[^ ]*\)#\1 #' \
+            -e 's/^-  /SUM/' >"${2}"
+    popd >/dev/null
+}
+
 # "equery list" a potentially uninstalled board package
 query_available_package() {
     local pkg="$1"
@@ -656,6 +680,7 @@ finish_image() {
   local image_kconfig="${10}"
   local image_initrd_contents="${11}"
   local image_initrd_contents_wtd="${12}"
+  local image_disk_space_usage="${13}"
 
   local install_grub=0
   local disk_img="${BUILD_DIR}/${image_name}"
@@ -757,9 +782,6 @@ EOF
         "${BUILD_DIR}/${image_kconfig}"
   fi
 
-  write_contents "${root_fs_dir}" "${BUILD_DIR}/${image_contents}"
-  write_contents_with_technical_details "${root_fs_dir}" "${BUILD_DIR}/${image_contents_wtd}"
-
   # Zero all fs free space to make it more compressible so auto-update
   # payloads become smaller, not fatal since it won't work on linux < 3.2
   sudo fstrim "${root_fs_dir}" || true
@@ -814,18 +836,6 @@ EOF
         >"${BUILD_DIR}/pcrs/kernel.config"
   fi
 
-  if [[ -n "${image_initrd_contents}" ]] || [[ -n "${image_initrd_contents_wtd}" ]]; then
-      "${BUILD_LIBRARY_DIR}/extract-initramfs-from-vmlinuz.sh" "${root_fs_dir}/boot/flatcar/vmlinuz-a" "${BUILD_DIR}/tmp_initrd_contents"
-      if [[ -n "${image_initrd_contents}" ]]; then
-          write_contents "${BUILD_DIR}/tmp_initrd_contents" "${BUILD_DIR}/${image_initrd_contents}"
-      fi
-
-      if [[ -n "${image_initrd_contents_wtd}" ]]; then
-          write_contents_with_technical_details "${BUILD_DIR}/tmp_initrd_contents" "${BUILD_DIR}/${image_initrd_contents_wtd}"
-      fi
-      rm -rf "${BUILD_DIR}/tmp_initrd_contents"
-  fi
-
   rm -rf "${BUILD_DIR}"/configroot
   cleanup_mounts "${root_fs_dir}"
   trap - EXIT
@@ -868,4 +878,31 @@ EOF
     popd >/dev/null
     rm -rf "${BUILD_DIR}/pcrs"
   fi
+
+  # Mount the final image again, as readonly, to generate some reports.
+  "${BUILD_LIBRARY_DIR}/disk_util" --disk_layout="${disk_layout}" \
+      mount --read_only "${disk_img}" "${root_fs_dir}"
+  trap "cleanup_mounts '${root_fs_dir}'" EXIT
+
+  write_contents "${root_fs_dir}" "${BUILD_DIR}/${image_contents}"
+  write_contents_with_technical_details "${root_fs_dir}" "${BUILD_DIR}/${image_contents_wtd}"
+
+  if [[ -n "${image_initrd_contents}" ]] || [[ -n "${image_initrd_contents_wtd}" ]]; then
+      "${BUILD_LIBRARY_DIR}/extract-initramfs-from-vmlinuz.sh" "${root_fs_dir}/boot/flatcar/vmlinuz-a" "${BUILD_DIR}/tmp_initrd_contents"
+      if [[ -n "${image_initrd_contents}" ]]; then
+          write_contents "${BUILD_DIR}/tmp_initrd_contents" "${BUILD_DIR}/${image_initrd_contents}"
+      fi
+
+      if [[ -n "${image_initrd_contents_wtd}" ]]; then
+          write_contents_with_technical_details "${BUILD_DIR}/tmp_initrd_contents" "${BUILD_DIR}/${image_initrd_contents_wtd}"
+      fi
+      rm -rf "${BUILD_DIR}/tmp_initrd_contents"
+  fi
+
+  if [[ -n "${image_disk_space_usage}" ]]; then
+      write_disk_space_usage "${root_fs_dir}" "${BUILD_DIR}/${image_disk_space_usage}"
+  fi
+
+  cleanup_mounts "${root_fs_dir}"
+  trap - EXIT
 }

build_library/prod_image_util.sh

@@ -76,6 +76,7 @@ create_prod_image() {
   local image_shim="${image_name%.bin}.shim"
   local image_initrd_contents="${image_name%.bin}_initrd_contents.txt"
   local image_initrd_contents_wtd="${image_name%.bin}_initrd_contents_wtd.txt"
+  local image_disk_usage="${image_name%.bin}_disk_usage.txt"
 
   start_image "${image_name}" "${disk_layout}" "${root_fs_dir}" "${update_group}"
 
@@ -141,7 +142,8 @@ EOF
       "${image_shim}" \
       "${image_kconfig}" \
       "${image_initrd_contents}" \
-      "${image_initrd_contents_wtd}"
+      "${image_initrd_contents_wtd}" \
+      "${image_disk_usage}"
 
   # Upload
   local to_upload=(
@@ -156,6 +158,7 @@ EOF
     "${BUILD_DIR}/${image_kconfig}"
     "${BUILD_DIR}/${image_initrd_contents}"
     "${BUILD_DIR}/${image_initrd_contents_wtd}"
+    "${BUILD_DIR}/${image_disk_usage}"
   )
 
   local files_to_evaluate=( "${BUILD_DIR}/${image_name}" )