deliver SystemRescue with an already initialized pacman key database

Initializing the pacman key database during boot can take considerable time
and there is no locking during this time against concurrent file access.
This can lead to problems when installing packages soon after reboot.
This also speeds up the boot process.

Additional disk space requirement is about 1 MByte.

Fixes #290

airootfs/etc/systemd/system/etc-pacman.d-gnupg.mount

@@ -1,8 +0,0 @@
-[Unit]
-Description=Temporary /etc/pacman.d/gnupg directory
-
-[Mount]
-What=tmpfs
-Where=/etc/pacman.d/gnupg
-Type=tmpfs
-Options=mode=0755

airootfs/etc/systemd/system/pacman-init.service

@@ -1,13 +0,0 @@
-[Unit]
-Description=Initializes Pacman keyring
-Requires=etc-pacman.d-gnupg.mount
-After=etc-pacman.d-gnupg.mount
-
-[Service]
-Type=oneshot
-RemainAfterExit=yes
-ExecStart=/usr/bin/pacman-key --init
-ExecStart=/usr/bin/pacman-key --populate
-
-[Install]
-WantedBy=multi-user.target

airootfs/root/customize_airootfs.sh

@@ -2,6 +2,8 @@
 
 set -e -u
 
+echo "customize_airootfs.sh started..."
+
 sed -i 's/#\(en_US\.UTF-8\)/\1/' /etc/locale.gen
 locale-gen
 
@@ -35,7 +37,6 @@ ln -sf /run/archiso/config/sysrescue-effective-config.json /etc/sysrescue/sysres
 systemctl enable NetworkManager.service
 systemctl enable iptables.service
 systemctl enable ip6tables.service
-systemctl enable pacman-init.service
 systemctl enable choose-mirror.service
 systemctl enable sshd.service
 systemctl enable sysrescue-initialize.service
@@ -53,6 +54,11 @@ systemctl mask updatedb.timer
 # ldconfig ("Rebuild Dynamic Linker Cache") unnecessarily slows down boot some time after the release
 systemctl mask ldconfig.service
 
+# setup pacman signing key storage
+/usr/bin/pacman-key --init
+/usr/bin/pacman-key --populate
+rm -f /etc/pacman.d/gnupg/*~
+
 # Provide additional commands (using busybox instead of binutils to save space)
 ln -sf /usr/bin/busybox /usr/local/bin/ar
 ln -sf /usr/bin/busybox /usr/local/bin/strings

build.sh

@@ -225,6 +225,9 @@ make_customize_airootfs() {
 
     setarch ${arch} mkarchiso ${verbose} -w "${work_dir}/${arch}" -C "${work_dir}/pacman.conf" -D "${install_dir}" -r '/root/customize_airootfs.sh' run
 
+    # unmount chroot /dev again as it could have been busy before due to gpg-agent
+    umount ${work_dir}/${arch}/airootfs/dev
+
     rm -f ${work_dir}/${arch}/airootfs/root/customize_airootfs.sh
 
     # change pacman config in airootfs to use snapshot repo by default