configs: add prepare-shard-media, rename discover-and-mount-sdcard to discover-shard

configs/airgap/airootfs/root/.bash_profile

@@ -4,7 +4,7 @@ Airgap Arch Linux with Keyfork is best used with a removable SD card to store
 shard files and other persistent media. After inserting an SD card, run the
 following command to mount any unmounted SD cards and find any Shard files:
 
-  # discover-and-mount-sdcard
+  # discover-shard
 
 This guide will assume the discovered Shard file is listed as:
   /media/mmcblk0p1/shards.pgp
@@ -15,8 +15,9 @@ where M is the minimum amount of users required to recreate the secret and N is
 is the total amount of shardholders. An additional value, K, will be used to
 denote the amount of smartcards (i.e., backups) to provision per shardholder.
 
+  # prepare-shard-media
   # keyfork wizard generate-shard-secret --threshold \$M --max \$N
-    --keys-per-shard \$K --output /media/mmcblk0p1/shards.pgp
+    --keys-per-shard \$K --output /media/sdcard/shards.pgp
 
 The Keyfork server can be started using a Shard-secred secret locally, if all
 shardholders are present, or using a QR-based remote recovery. The shard file
@@ -39,22 +40,48 @@ For more information, run:
 EOF
 }
 
-discover-and-mount-sdcard() {
+amount() {
+  partition="$1"
+  media="$1"
+  if [ ! -z "$2" ]; then
+    media="$2"
+  fi
+  echo "Automatically mounting /dev/$partition to /media/$media"
+  mkdir -p "/media/$media"
+  umount "/media/$partition" 2>/dev/null
+  mount $MOUNT_OPTS "/dev/$partition" "/media/$media"
+}
+
+discover-shard() {
   MOUNT_OPTS="-o relatime,utf8,flush,umask=0000"
 
   lsblk -nlo NAME,FSTYPE | awk '$2 == "vfat" { print $1 }' | while read partition; do
-    echo "Automatically mounting /dev/$partition to /media/$partition"
-    mkdir -p "/media/$partition"
-    umount "/media/$partition" 2>/dev/null
-    mount $MOUNT_OPTS "/dev/$partition" "/media/$partition"
+    amount "$partition"
     find "/media/$partition" -name '*.pgp' -maxdepth 2 | while read file; do
       echo "Found potential shardfile: $file"
     done
   done
 }
 
-echo
+prepare-shard-media() {
+  echo "Please re-insert the SD card"
+  udevadm monitor --udev | while read udev ts operation path type; do
+    if [ "$type" = "(block)" -a "$operation" = "add" ]; then
+      partition="$(echo "$path" | cut -d/ -f12)"
+      if [ ! -z "$partition" ]; then
+        amount "$partition" "sdcard"
+        # Weird quirk with bash: if udev doesn't have anything else printing,
+        # it won't trigger the start of the next loop, and therefore won't
+        # "break" the loop. Run `udevadm trigger` to give udevadm more things
+        # to send to `read`.
+        udevadm trigger
+        break
+      fi
+    fi
+  done
+}
+
 help
 echo
-discover-and-mount-sdcard
+discover-shard
 echo