archiso/mkarchiso: general bash improvements

Quote all variables.
Terminate option processing using '--' for commands that support it.
Do not hardcode file descriptor.
Compare integers with arithmetic comparison instead of string comparison.
Replace echo with printf.
Use heredoc for usage text.
Don't print INFO messages when quiet is set.
Export SOURCE_DATE_EPOCH.

archiso/mkarchiso

@@ -4,10 +4,13 @@
 
 set -e -u
 
-export LANG=C
+# Control the environment
+umask 0022
+export LANG="C"
+export SOURCE_DATE_EPOCH="${SOURCE_DATE_EPOCH:-"$(date +%s)"}"
 
-app_name=${0##*/}
-arch=$(uname -m)
+app_name="${0##*/}"
+arch="$(uname -m)"
 pkg_list=()
 run_cmd=""
 quiet="y"
@@ -20,13 +23,14 @@ work_dir="work"
 out_dir="out"
 sfs_mode="sfs"
 sfs_comp="xz"
-gpg_key=
+gpg_key=""
 
 # Show an INFO message
 # $1: message string
 _msg_info() {
     local _msg="${1}"
-    echo "[mkarchiso] INFO: ${_msg}"
+    [[ "${quiet}" == "y" ]] || printf '[%s] INFO: %s\n' "${app_name}" "${_msg}"
+
 }
 
 # Show an ERROR message then exit with status
@@ -35,83 +39,83 @@ _msg_info() {
 _msg_error() {
     local _msg="${1}"
     local _error=${2}
-    echo
-    echo "[mkarchiso] ERROR: ${_msg}"
-    echo
-    if [[ ${_error} -gt 0 ]]; then
+    printf '\n[%s] ERROR: %s\n\n' "${app_name}" "${_msg}" >&2
+    if (( _error > 0 )); then
         exit "${_error}"
     fi
 }
 
 _chroot_init() {
-    mkdir -p ${work_dir}/airootfs
+    mkdir -p -- "${work_dir}/airootfs"
     _pacman base syslinux
 }
 
 _chroot_run() {
-    eval arch-chroot ${work_dir}/airootfs "${run_cmd}"
+    eval -- arch-chroot "${work_dir}/airootfs" "${run_cmd}"
 }
 
 _mount_airootfs() {
     trap "_umount_airootfs" EXIT HUP INT TERM
-    mkdir -p "${work_dir}/mnt/airootfs"
+    mkdir -p -- "${work_dir}/mnt/airootfs"
     _msg_info "Mounting '${work_dir}/airootfs.img' on '${work_dir}/mnt/airootfs'"
-    mount "${work_dir}/airootfs.img" "${work_dir}/mnt/airootfs"
+    mount -- "${work_dir}/airootfs.img" "${work_dir}/mnt/airootfs"
     _msg_info "Done!"
 }
 
 _umount_airootfs() {
     _msg_info "Unmounting '${work_dir}/mnt/airootfs'"
-    umount -d "${work_dir}/mnt/airootfs"
+    umount -d -- "${work_dir}/mnt/airootfs"
     _msg_info "Done!"
-    rmdir "${work_dir}/mnt/airootfs"
+    rmdir -- "${work_dir}/mnt/airootfs"
     trap - EXIT HUP INT TERM
 }
 
 # Show help usage, with an exit status.
 # $1: exit status number.
-_usage ()
-{
-    echo "usage ${app_name} [options] command <command options>"
-    echo " general options:"
-    echo "    -p PACKAGE(S)    Package(s) to install, can be used multiple times"
-    echo "    -r <command>     Run <command> inside airootfs"
-    echo "    -C <file>        Config file for pacman."
-    echo "                     Default: '${pacman_conf}'"
-    echo "    -L <label>       Set a label for the disk"
-    echo "                     Default: '${iso_label}'"
-    echo "    -P <publisher>   Set a publisher for the disk"
-    echo "                     Default: '${iso_publisher}'"
-    echo "    -A <application> Set an application name for the disk"
-    echo "                     Default: '${iso_application}'"
-    echo "    -D <install_dir> Set an install_dir. All files will by located here."
-    echo "                     Default: '${install_dir}'"
-    echo "                     NOTE: Max 8 characters, use only [a-z0-9]"
-    echo "    -w <work_dir>    Set the working directory"
-    echo "                     Default: '${work_dir}'"
-    echo "    -o <out_dir>     Set the output directory"
-    echo "                     Default: '${out_dir}'"
-    echo "    -s <sfs_mode>    Set SquashFS image mode (img or sfs)"
-    echo "                     img: prepare airootfs.sfs for dm-snapshot usage"
-    echo "                     sfs: prepare airootfs.sfs for overlayfs usage"
-    echo "                     Default: ${sfs_mode}"
-    echo "    -c <comp_type>   Set SquashFS compression type (gzip, lzma, lzo, xz, zstd)"
-    echo "                     Default: '${sfs_comp}'"
-    echo "    -v               Enable verbose output"
-    echo "    -h               This message"
-    echo " commands:"
-    echo "   init"
-    echo "      Make base layout and install base group"
-    echo "   install"
-    echo "      Install all specified packages (-p)"
-    echo "   run"
-    echo "      run command specified by -r"
-    echo "   prepare"
-    echo "      build all images"
-    echo "   pkglist"
-    echo "      make a pkglist.txt of packages installed on airootfs"
-    echo "   iso <image name>"
-    echo "      build an iso image from the working dir"
+_usage () {
+    IFS='' read -r -d '' usagetext <<ENDUSAGETEXT || true
+usage ${app_name} [options] command <command options>
+ general options:
+    -p PACKAGE(S)    Package(s) to install, can be used multiple times
+    -r <command>     Run <command> inside airootfs
+    -C <file>        Config file for pacman.
+                     Default: '${pacman_conf}'
+    -L <label>       Set a label for the disk
+                     Default: '${iso_label}'
+    -P <publisher>   Set a publisher for the disk
+                     Default: '${iso_publisher}'
+    -A <application> Set an application name for the disk
+                     Default: '${iso_application}'
+    -D <install_dir> Set an install_dir. All files will by located here.
+                     Default: '${install_dir}'
+                     NOTE: Max 8 characters, use only [a-z0-9]
+    -w <work_dir>    Set the working directory
+                     Default: '${work_dir}'
+    -o <out_dir>     Set the output directory
+                     Default: '${out_dir}'
+    -s <sfs_mode>    Set SquashFS image mode (img or sfs)
+                     img: prepare airootfs.sfs for dm-snapshot usage
+                     sfs: prepare airootfs.sfs for overlayfs usage
+                     Default: '${sfs_mode}'
+    -c <comp_type>   Set SquashFS compression type (gzip, lzma, lzo, xz, zstd)
+                     Default: '${sfs_comp}'
+    -v               Enable verbose output
+    -h               This message
+ commands:
+   init
+      Make base layout and install base group
+   install
+      Install all specified packages (-p)
+   run
+      run command specified by -r
+   prepare
+      build all images
+   pkglist
+      make a pkglist.txt of packages installed on airootfs
+   iso <image name>
+      build an iso image from the working dir
+ENDUSAGETEXT
+    printf '%s\n' "${usagetext}"
     exit "${1}"
 }
 
@@ -119,7 +123,7 @@ _usage ()
 # $1: init | install | run | prepare | iso
 _show_config () {
     local _mode="$1"
-    echo
+    printf '\n'
     _msg_info "Configuration settings"
     _msg_info "                  Command:   ${command_name}"
     _msg_info "             Architecture:   ${arch}"
@@ -147,18 +151,17 @@ _show_config () {
             _msg_info "         Disk application:   ${iso_application}"
             ;;
     esac
-    echo
+    printf '\n'
 }
 
 # Install desired packages to airootfs
-_pacman ()
-{
+_pacman () {
     _msg_info "Installing packages to '${work_dir}/airootfs/'..."
 
     if [[ "${quiet}" = "y" ]]; then
-        pacstrap -C "${pacman_conf}" -c -G -M "${work_dir}/airootfs" "$@" &> /dev/null
+        pacstrap -C "${pacman_conf}" -c -G -M -- "${work_dir}/airootfs" "$@" &> /dev/null
     else
-        pacstrap -C "${pacman_conf}" -c -G -M "${work_dir}/airootfs" "$@"
+        pacstrap -C "${pacman_conf}" -c -G -M -- "${work_dir}/airootfs" "$@"
     fi
 
     _msg_info "Packages installed successfully!"
@@ -197,7 +200,7 @@ _cleanup () {
         find "${work_dir}/airootfs/var/tmp" -mindepth 1 -delete
     fi
     # Delete package pacman related files.
-    find "${work_dir}" \( -name "*.pacnew" -o -name "*.pacsave" -o -name "*.pacorig" \) -delete
+    find "${work_dir}" \( -name '*.pacnew' -o -name '*.pacsave' -o -name '*.pacorig' \) -delete
     _msg_info "Done!"
 }
 
@@ -208,21 +211,21 @@ _mkairootfs_img () {
     fi
 
     _msg_info "Creating ext4 image of 32GiB..."
-    truncate -s 32G "${work_dir}/airootfs.img"
-    local _qflag=""
+    truncate -s 32G -- "${work_dir}/airootfs.img"
     if [[ "${quiet}" == "y" ]]; then
-        _qflag="-q"
+        mkfs.ext4 -q -O '^has_journal,^resize_inode' -E 'lazy_itable_init=0' -m 0 -F -- "${work_dir}/airootfs.img"
+    else
+        mkfs.ext4 -O '^has_journal,^resize_inode' -E 'lazy_itable_init=0' -m 0 -F -- "${work_dir}/airootfs.img"
     fi
-    mkfs.ext4 ${_qflag} -O ^has_journal,^resize_inode -E lazy_itable_init=0 -m 0 -F "${work_dir}/airootfs.img"
-    tune2fs -c 0 -i 0 "${work_dir}/airootfs.img" &> /dev/null
+    tune2fs -c 0 -i 0 -- "${work_dir}/airootfs.img" &> /dev/null
     _msg_info "Done!"
     _mount_airootfs
     _msg_info "Copying '${work_dir}/airootfs/' to '${work_dir}/mnt/airootfs/'..."
-    cp -aT "${work_dir}/airootfs/" "${work_dir}/mnt/airootfs/"
-    chown root:root "${work_dir}/mnt/airootfs/"
+    cp -aT -- "${work_dir}/airootfs/" "${work_dir}/mnt/airootfs/"
+    chown root:root -- "${work_dir}/mnt/airootfs/"
     _msg_info "Done!"
     _umount_airootfs
-    mkdir -p "${work_dir}/iso/${install_dir}/${arch}"
+    mkdir -p -- "${work_dir}/iso/${install_dir}/${arch}"
     _msg_info "Creating SquashFS image, this may take some time..."
     if [[ "${quiet}" = "y" ]]; then
         mksquashfs "${work_dir}/airootfs.img" "${work_dir}/iso/${install_dir}/${arch}/airootfs.sfs" -noappend \
@@ -232,7 +235,7 @@ _mkairootfs_img () {
             -comp "${sfs_comp}"
     fi
     _msg_info "Done!"
-    rm "${work_dir}/airootfs.img"
+    rm -- "${work_dir}/airootfs.img"
 }
 
 # Makes a SquashFS filesystem from a source directory.
@@ -241,7 +244,7 @@ _mkairootfs_sfs () {
         _msg_error "The path '${work_dir}/airootfs' does not exist" 1
     fi
 
-    mkdir -p "${work_dir}/iso/${install_dir}/${arch}"
+    mkdir -p -- "${work_dir}/iso/${install_dir}/${arch}"
     _msg_info "Creating SquashFS image, this may take some time..."
     if [[ "${quiet}" = "y" ]]; then
         mksquashfs "${work_dir}/airootfs" "${work_dir}/iso/${install_dir}/${arch}/airootfs.sfs" -noappend \
@@ -255,17 +258,17 @@ _mkairootfs_sfs () {
 
 _mkchecksum () {
     _msg_info "Creating checksum file for self-test..."
-    cd "${work_dir}/iso/${install_dir}/${arch}"
+    cd -- "${work_dir}/iso/${install_dir}/${arch}"
     sha512sum airootfs.sfs > airootfs.sha512
-    cd "${OLDPWD}"
+    cd -- "${OLDPWD}"
     _msg_info "Done!"
 }
 
 _mksignature () {
     _msg_info "Creating signature file..."
-    cd "${work_dir}/iso/${install_dir}/${arch}"
+    cd -- "${work_dir}/iso/${install_dir}/${arch}"
     gpg --detach-sign --default-key "${gpg_key}" airootfs.sfs
-    cd "${OLDPWD}"
+    cd -- "${OLDPWD}"
     _msg_info "Done!"
 }
 
@@ -273,8 +276,7 @@ command_pkglist () {
     _show_config pkglist
 
     _msg_info "Creating a list of installed packages on live-enviroment..."
-    pacman -Q --sysroot "${work_dir}/airootfs" > \
-        "${work_dir}/iso/${install_dir}/pkglist.${arch}.txt"
+    pacman -Q --sysroot "${work_dir}/airootfs" > "${work_dir}/iso/${install_dir}/pkglist.${arch}.txt"
     _msg_info "Done!"
 
 }
@@ -302,7 +304,7 @@ command_iso () {
 
     _show_config iso
 
-    mkdir -p "${out_dir}"
+    mkdir -p -- "${out_dir}"
     _msg_info "Creating ISO image..."
     local _qflag=""
     if [[ "${quiet}" == "y" ]]; then
@@ -313,7 +315,7 @@ command_iso () {
             -volid "${iso_label}" \
             -appid "${iso_application}" \
             -publisher "${iso_publisher}" \
-            -preparer "prepared by mkarchiso" \
+            -preparer "prepared by ${app_name}" \
             -eltorito-boot isolinux/isolinux.bin \
             -eltorito-catalog isolinux/boot.cat \
             -no-emul-boot -boot-load-size 4 -boot-info-table \
@@ -329,7 +331,7 @@ command_iso () {
             -volid "${iso_label}" \
             -appid "${iso_application}" \
             -publisher "${iso_publisher}" \
-            -preparer "prepared by mkarchiso" \
+            -preparer "prepared by ${app_name}" \
             -eltorito-boot isolinux/isolinux.bin \
             -eltorito-catalog isolinux/boot.cat \
             -no-emul-boot -boot-load-size 4 -boot-info-table \
@@ -338,7 +340,7 @@ command_iso () {
             -output "${out_dir}/${img_name}" \
             "${work_dir}/iso/"
     fi
-    _msg_info "Done! | $(ls -sh "${out_dir}/${img_name}")"
+    _msg_info "Done! | $(ls -sh -- "${out_dir}/${img_name}")"
 }
 
 # create airootfs.sfs filesystem, and push it in "iso" directory.
@@ -364,7 +366,7 @@ command_install () {
         _msg_error "Pacman config file '${pacman_conf}' does not exist" 1
     fi
 
-    if [[ "${#pkg_list[@]}" -eq 0 ]]; then
+    if (( ${#pkg_list[@]} == 0 )); then
         _msg_error "Packages must be specified" 0
         _usage 1
     fi
@@ -384,12 +386,6 @@ command_run() {
     _chroot_run
 }
 
-if [[ "${EUID}" -ne 0 ]]; then
-    _msg_error "This script must be run as root." 1
-fi
-
-umask 0022
-
 while getopts 'p:r:C:L:P:A:D:w:o:s:c:g:vh' arg; do
     case "${arg}" in
         p)
@@ -397,13 +393,13 @@ while getopts 'p:r:C:L:P:A:D:w:o:s:c:g:vh' arg; do
             pkg_list+=("${opt_pkg_list[@]}")
             ;;
         r) run_cmd="${OPTARG}" ;;
-        C) pacman_conf="${OPTARG}" ;;
+        C) pacman_conf="$(realpath -- "${OPTARG}")" ;;
         L) iso_label="${OPTARG}" ;;
         P) iso_publisher="${OPTARG}" ;;
         A) iso_application="${OPTARG}" ;;
         D) install_dir="${OPTARG}" ;;
-        w) work_dir="${OPTARG}" ;;
-        o) out_dir="${OPTARG}" ;;
+        w) work_dir="$(realpath -- "${OPTARG}")" ;;
+        o) out_dir="$(realpath -- "${OPTARG}")" ;;
         s) sfs_mode="${OPTARG}" ;;
         c) sfs_comp="${OPTARG}" ;;
         g) gpg_key="${OPTARG}" ;;
@@ -416,9 +412,13 @@ while getopts 'p:r:C:L:P:A:D:w:o:s:c:g:vh' arg; do
     esac
 done
 
+if (( EUID != 0 )); then
+    _msg_error "${app_name} must be run as root." 1
+fi
+
 shift $((OPTIND - 1))
 
-if [[ $# -lt 1 ]]; then
+if (( $# < 1 )); then
     _msg_error "No command specified" 0
     _usage 1
 fi
@@ -441,7 +441,7 @@ case "${command_name}" in
         command_pkglist
         ;;
     iso)
-        if [[ $# -lt 2 ]]; then
+        if (( $# < 2 )); then
             _msg_error "No image specified" 0
             _usage 1
         fi