mostly pointless tweaking of inject-subiquity-snap

scripts/inject-subiquity-snap.sh

@@ -11,7 +11,7 @@ while getopts ":ifc:" opt; do
             interactive=yes
             ;;
         c)
-            cmds=$OPTARG
+            cmds="${OPTARG}"
             ;;
         f)
             edit_filesystem=yes
@@ -26,74 +26,67 @@ shift $((OPTIND-1))
 
 # inject-subiquity-snap.sh $old_iso $subiquity_snap $new_iso
 
-OLD_ISO=$(readlink -f $1)
-SUBIQUITY_SNAP_PATH=$(readlink -f $2)
-SUBIQUITY_SNAP=$(basename $SUBIQUITY_SNAP_PATH)
-NEW_ISO=$(readlink -f $3)
+OLD_ISO="$(readlink -f $1)"
+SUBIQUITY_SNAP_PATH="$(readlink -f $2)"
+SUBIQUITY_SNAP="$(basename $SUBIQUITY_SNAP_PATH)"
+NEW_ISO="$(readlink -f $3)"
 
-tmpdir=$(mktemp -d)
-cd $tmpdir
+tmpdir="$(mktemp -d)"
+cd "${tmpdir}"
 
 _MOUNTS=()
 
-mount () {
-    command mount "$@"
-    _MOUNTS=(${!#} ${_MOUNTS[@]+"${_MOUNTS[@]}"})
+do_mount () {
+    local mountpoint="${!#}"
+    mkdir "${mountpoint}"
+    mount "$@"
+    _MOUNTS=("${mountpoint}" "${_MOUNTS[@]+"${_MOUNTS[@]}"}")
 }
 
 cleanup () {
-    for m in ${_MOUNTS[@]+"${_MOUNTS[@]}"}; do
-        umount $m
+    for m in "${_MOUNTS[@]+"${_MOUNTS[@]}"}"; do
+        umount "${m}"
     done
-    rm -rf $tmpdir
+    rm -rf "${tmpdir}"
 }
 
 trap cleanup EXIT
 
 add_overlay() {
-    lower=$1
-    mountpoint=$2
-    work=$(mktemp -dp $tmpdir)
-    upper=$(mktemp -dp $tmpdir)
-    chmod go+rx $work $upper
-    mount -t overlay overlay -o lowerdir=$lower,upperdir=$upper,workdir=$work $mountpoint
+    local lower="$1"
+    local mountpoint="$2"
+    local work="$(mktemp -dp "${tmpdir}")"
+    local upper="$(mktemp -dp "${tmpdir}")"
+    chmod go+rx "${work}" "${upper}"
+    do_mount -t overlay overlay -o lowerdir="${lower}",upperdir="${upper}",workdir="${work}" "${mountpoint}"
 }
 
-mkdir old_iso
-
-mount -t iso9660 -o loop $OLD_ISO old_iso
-
-mkdir old_installer
-
-mount -t squashfs old_iso/casper/installer.squashfs old_installer
-
-mkdir new_installer
+do_mount -t iso9660 -o loop "${OLD_ISO}" old_iso
+do_mount -t squashfs old_iso/casper/installer.squashfs old_installer
 add_overlay old_installer new_installer
 
 
-CORE_SNAP=$(cd old_installer/var/lib/snapd/seed/snaps/; ls -1 core*.snap)
+CORE_SNAP="$(cd old_installer/var/lib/snapd/seed/snaps/; ls -1 core*.snap)"
 
 cat <<EOF > new_installer/var/lib/snapd/seed/seed.yaml
 snaps:
  - name: core
    channel: stable
-   file: ${CORE_SNAP}
+   file: "${CORE_SNAP}"
  - name: subiquity
    unasserted: true
    classic: true
-   file: ${SUBIQUITY_SNAP}
+   file: "${SUBIQUITY_SNAP}"
 EOF
 
 rm -f new_installer/var/lib/snapd/seed/assertions/subiquity*.assert
 rm -f new_installer/var/lib/snapd/seed/snaps/subiquity*.snap
-cp $SUBIQUITY_SNAP_PATH new_installer/var/lib/snapd/seed/snaps/
+cp "${SUBIQUITY_SNAP_PATH}" new_installer/var/lib/snapd/seed/snaps/
 
-mkdir new_iso
 add_overlay old_iso new_iso
 
 if [ "$edit_filesystem" = "yes" ]; then
-    mkdir old_filesystem new_filesystem
-    mount -t squashfs old_iso/casper/filesystem.squashfs old_filesystem
+    do_mount -t squashfs old_iso/casper/filesystem.squashfs old_filesystem
     add_overlay old_filesystem new_filesystem
 fi
 
@@ -115,7 +108,7 @@ mksquashfs new_installer new_iso/casper/installer.squashfs
 
 xorriso -as mkisofs -r -checksum_algorithm_iso md5,sha1 \
 	-V Ubuntu\ custom\ amd64 \
-	-o $NEW_ISO \
+	-o "${NEW_ISO}" \
 	-cache-inodes -J -l \
 	-b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot \
 	-boot-load-size 4 -boot-info-table \