use genisoimage to create a mac dmg file

build.sh

@@ -79,14 +79,14 @@ function fail {
 
   # apply patch to load netpd at start
   patch -s ${work_dir}/${app_bundle_name}/Contents/Resources/tcl/pd-gui.tcl < files/pd-gui.tcl.patch || fail
+  # copy icons file
   cp files/netpd.icns ${work_dir}/${app_bundle_name}/Contents/Resources/ || fail
+  # construct a Info.plist
   sed -f <(echo "${info_plist_replacements}") files/Info.plist > ${work_dir}/${app_bundle_name}/Contents/Info.plist || fail
 
-  # create archive
-  (
-    cd "${work_dir}"
-    tar cf "../${app_name}-${app_version}.tar.gz" "${app_bundle_name}"  || fail
-  ) || fail
+  # create disk image
+  genisoimage -quiet -V "${app_name}-${app_version}" -D -R -apple -no-pad -o "${app_name}-${app_version}.dmg" "${work_dir}" || fail
 
+  # clean up
   rm -r "${work_dir}"
 )