Implement fstab-like addon config

For now all it handles is bind mounting and squashfs
images that have to overlay at the root. The config
file syntax is obviously borrowed from fstab. This
is far from final, much of it could use some cleanup.

Signed-off-by: Simo Leone <simo@archlinux.org>

addon_config

@@ -1,17 +1,8 @@
-# This script gets run around the end of the archiso hook
-# These are some typical examples of what addons may need
+# img - location of image/directory to mount relative to addons directory
+# mount point - absolute location on the post-initrd root
+# type - either 'bind' or 'squashfs' for now
 
-# installer package payload in a plain directory
-mkdir -p /real_root/packages
-mount -o bind $BOOT_MOUNT/addons/core /real_root/packages
+# syntax: <img> <mount point> <type>
 
-# a squashed livecd-specific overlay for a pristine system
-#TODO: we should keep track of used loop devices in case of multiple images
-mkdir -p /tmpfs/mnt/live_overlay
-if ! /bin/losetup /dev/loop1 "${BOOT_MOUNT}/addons/live_overlay.sqfs" >/dev/null 2>&1; then
-    echo "ERROR: Cannot mount loop device /dev/loop1...aborting"
-fi
-/bin/mount -r -t squashfs /dev/loop1 /tmpfs/mnt/live_overlay
-mount -t unionfs -o remount,add=/tmpfs/squashfs_root:/tmpfs/mnt/live_overlay=ro none /real_root
-
-# vim:ft=sh:ts=4:sw=4:et:
+core                    /packages           bind
+live_overlay.sqfs       /                   squashfs

hooks/archiso

@@ -31,13 +31,37 @@ run_hook ()
 
     msg ":: Mounting root (union) filesystem"
     /bin/modprobe -q unionfs >/dev/null 2>&1
-    /bin/mount -t unionfs -o dirs=/tmpfs=rw:/tmpfs/squashfs_root=ro none /real_root
+    /bin/mount -t unionfs -o dirs=/tmpfs=rw none /real_root
 
-    addon_conf="${BOOT_MOUNT}/addons/config"
-    if [ -e "${addon_conf}" ]; then
+    # TODO: some of this could be broken into functions
+    LOOP_NUM="1"
+    addon_dir="${BOOT_MOUNT}/addons"
+    if [ -e "${addon_dir}/config" ]; then
         msg ":: Mounting addons"
-        . $addon_conf
+        while read img mountpoint type; do
+            # check if this line is a comment (starts with #)
+            [ "${img#'#'}" != "${img}" ] && continue
+
+            if [ "${type}" = "bind" ]; then
+                msg "   Binding ${img} to ${mountpoint}"
+                mkdir -p /real_root${mountpoint}
+                /bin/mount -o bind ${addon_dir}/$img /real_root${mountpoint}
+            elif [ "${type}" = "squashfs" ]; then
+                msg "   Adding new union branch: ${img}"
+                mkdir -p "/tmpfs/mnt/loop${LOOP_NUM}"
+                if ! /bin/losetup "/dev/loop${LOOP_NUM}" ${addon_dir}/$img > /dev/null 2>&1; then
+                    echo "ERROR: Cannot mount loop device /dev/loop${LOOP_NUM}"
+                    echo "       Couldn't mount all addons"
+                    break
                 fi
+                /bin/mount -r -t squashfs "/dev/loop${LOOP_NUM}" "/tmpfs/mnt/loop${LOOP_NUM}"
+                /bin/mount -t unionfs -o remount,add=:/tmpfs/mnt/loop${LOOP_NUM}=ro none "/real_root"
+                LOOP_NUM=$(( $LOOP_NUM + 1 ))
+            fi
+        done < ${addon_dir}/config
+    fi
+
+    /bin/mount -t unionfs -o remount,add=:/tmpfs/squashfs_root=ro none /real_root
 
     if [ -d /proc/sys/dev/cdrom ]; then
         echo 0 > /proc/sys/dev/cdrom/lock