Add multi-layered seed support

The available filesystem with the largest number of seeds will be chosen
for the root of the initial install.

1 files changed, 44 insertions, 4 deletions

diff --git a/old-school/lvm-create.sh b/old-school/lvm-create.sh
index e6f4eea..743b83a 100644
--- a/old-school/lvm-create.sh
+++ b/old-school/lvm-create.sh
@@ -31,9 +31,19 @@ init_samizdat()
   local imgfile="$1" megs="$2" keyfile="$3" dev
 
   init_samizdat_blockdev "$imgfile" "$megs" "$keyfile" || return
-  local blockdev=/dev/mapper/samizdatcrypt
+  local blockdev=/dev/mapper/samizdatcrypt uuid
+
+  for fs in /cdrom/live/*.btrfs; do
+      losetup -f "$fs" || return
+  done
+  modprobe btrfs || return
+  btrfs device scan || return
+
+  uuid=$(choose_uuid) || return
+  [ "$uuid" ]
+
+  mount -t btrfs -o subvol=ROOT UUID="$uuid" /root || return
 
-  mount -t btrfs -o subvol=ROOT /cdrom/live/filesystem.btrfs /root || return
   btrfs device add "$blockdev" /root || return
   mount -o rw,remount /root || return
   btrfs subvolume create /root/gpg || return
@@ -53,14 +63,44 @@ init_samizdat()
   bootdone root-mounted
 }
 
+# Get the uuid of the filesystem with the most devices,
+# excluding filesystems that don't incorporate loop devices.
+# This is used to choose the latest seed -- which should have
+# the most layers.
+choose_uuid()
+{
+    local seen_loop= seen_uuid= seen_devs=
+    btrfs filesystem show |
+        while read line; do
+            case "$line" in
+                Label*)
+                    seen_uuid=${line##*uuid: }
+                    seen_devs=
+                    seen_loop=
+                    ;;
+                *Total\ devices*)
+                    seen_devs=${line#*Total devices }
+                    seen_devs=${seen_devs%% *}
+                    ;;
+                *path\ /dev/loop*)
+                    seen_loop=t;;
+            esac
+            [ "$seen_loop" ] && echo "$seen_devs $seen_uuid"
+        done |
+        uniq | sort -nr | head -n1 | (read _ x; echo $x)
+}
+
 open_samizdat()
 {
   open_samizdat_blockdev "$@" || return
-  local blockdev=/dev/mapper/samizdatcrypt
-  losetup -f /cdrom/live/filesystem.btrfs || return
+  local blockdev=/dev/mapper/samizdatcrypt fs
+  for fs in /cdrom/live/*.btrfs; do
+    losetup -f "$fs" || return
+  done
   modprobe btrfs || return
   btrfs device scan || return
   mount -t btrfs -o subvol=ROOT "$blockdev" /root || return
+  LoSetup -D
   bootdone root-mounted
 }