mkarchiso: add a -r option to delete the working directory

`-r` will instruct to delete the working directory at the end of a
`mkarchiso` run.

If the specified directory already exists, then it will not be deleted
and instead produce a warning.

Implements #211

CHANGELOG.rst

@@ -11,6 +11,7 @@ Added
 - Added classes for Memtest86+ and UEFI Shell menuentries.
 - Add foot-terminfo and wezterm-terminfo packages to releng to support terminal emulators using them. E.g. when
   installing via SSH.
+- Add a new ``-r`` option to ``mkarchiso`` that deletes the working directly after the build.
 
 Changed
 -------

archiso/mkarchiso

@@ -39,6 +39,7 @@ pacman_conf=""
 packages=""
 bootstrap_packages=""
 pacstrap_dir=""
+declare -i rm_work_dir=0
 buildmodes=()
 bootmodes=()
 airootfs_image_type=""
@@ -110,6 +111,7 @@ usage: ${app_name} [options] <profile_dir>
                       Default: '${out_dir}'
      -p [package ..]  Package(s) to install.
                       Multiple packages are provided as quoted, space delimited list.
+     -r               Delete the working directory at the end.
      -v               Enable verbose output
      -w <work_dir>    Set the working directory
                       Default: '${work_dir}'
@@ -1658,6 +1660,9 @@ _set_overrides() {
     elif [[ -z "$quiet" ]]; then
         quiet="y"
     fi
+    if [[ -v override_rm_work_dir ]]; then
+        rm_work_dir="$override_rm_work_dir"
+    fi
 
     # Set variables that do not have overrides
     [[ -n "$airootfs_image_type" ]] || airootfs_image_type="squashfs"
@@ -1730,6 +1735,16 @@ _make_pkglist() {
     _msg_info "Done!"
 }
 
+# Create working directory
+_make_work_dir() {
+    if [[ ! -d "${work_dir}" ]]; then
+        install -d -- "${work_dir}"
+    elif (( rm_work_dir )); then
+        rm_work_dir=0
+        _msg_warning "Working directory removal requested, but '${work_dir}' already exists. It will not be removed!" 0
+    fi
+}
+
 # build the base for an ISO and/or a netboot target
 _build_iso_base() {
     local run_once_mode="base"
@@ -1741,7 +1756,7 @@ _build_iso_base() {
     isofs_dir="${work_dir}/iso"
 
     # Create working directory
-    [[ -d "${work_dir}" ]] || install -d -- "${work_dir}"
+    _run_once _make_work_dir
     # Write build date to file if it does not exist already
     [[ -e "${work_dir}/build_date" ]] || printf '%s\n' "$SOURCE_DATE_EPOCH" > "${work_dir}/build_date"
 
@@ -1820,9 +1835,14 @@ _build() {
     for buildmode in "${buildmodes[@]}"; do
         _run_once "_build_buildmode_${buildmode}"
     done
+    if (( rm_work_dir )); then
+        _msg_info 'Removing the working directory...'
+        rm -rf -- "${work_dir:?}/"
+        _msg_info 'Done!'
+    fi
 }
 
-while getopts 'c:p:C:L:P:A:D:w:m:o:g:G:vh?' arg; do
+while getopts 'c:p:C:L:P:A:D:w:m:o:g:G:vrh?' arg; do
     case "${arg}" in
         p) read -r -a override_pkg_list <<< "${OPTARG}" ;;
         C) override_pacman_conf="${OPTARG}" ;;
@@ -1837,6 +1857,7 @@ while getopts 'c:p:C:L:P:A:D:w:m:o:g:G:vh?' arg; do
         g) override_gpg_key="${OPTARG}" ;;
         G) override_gpg_sender="${OPTARG}" ;;
         v) override_quiet="n" ;;
+        r) declare -i override_rm_work_dir=1 ;;
         h|?) _usage 0 ;;
         *)
             _msg_error "Invalid argument '${arg}'" 0