fix(dmsquash-live): run checkisomd5 on correct device

When the new grub2 iso is written to a usb drive the disk label points
to a partition that does not include the full iso image. This causes
checkisomd5 to run with the wrong data and it fails.

This patch adds a check that will test to see if there is a parent
device that is a disk, and to run checkisomd5 on it instead of on the
partition pointed to by the label.

When running from an iso this will return the original
/dev/disk/by-label/ path, and when running from a usb drive it will
return the parent device (eg. /dev/sda).

Resolves: rhbz#2107858

modules.d/90dmsquash-live/dmsquash-live-root.sh

@@ -33,19 +33,46 @@ overlay_size=$(getarg rd.live.overlay.size=)
 getargbool 0 rd.live.overlay.thin && thin_snapshot="yes"
 getargbool 0 rd.live.overlay.overlayfs && overlayfs="yes"
 
+# Take a path to a disk label and return the parent disk if it is a partition
+# Otherwise returns the original path
+function get_check_dev() {
+    local _udevinfo
+    dev_path="$(udevadm info -q path --name "$1")"
+    _udevinfo="$(udevadm info -q property --path "${dev_path}")"
+    strstr "$_udevinfo" "DEVTYPE=partition" || {
+        echo "$1"
+        return
+    }
+    parent="${dev_path%/*}"
+    _udevinfo="$(udevadm info -q property --path "${parent}")"
+    strstr "$_udevinfo" "DEVTYPE=disk" || {
+        echo "$1"
+        return
+    }
+    strstr "$_udevinfo" "ID_FS_TYPE=iso9660" || {
+        echo "$1"
+        return
+    }
+
+    # Return the name of the parent disk device
+    echo "$_udevinfo" | grep "DEVNAME=" | sed 's/DEVNAME=//'
+}
+
+# Find the right device to run check on
+check_dev=$(get_check_dev "$livedev")
 # CD/DVD media check
-[ -b "$livedev" ] && fs=$(blkid -s TYPE -o value "$livedev")
+[ -b "$check_dev" ] && fs=$(blkid -s TYPE -o value "$check_dev")
 if [ "$fs" = "iso9660" -o "$fs" = "udf" ]; then
     check="yes"
 fi
 getarg rd.live.check -d check || check=""
 if [ -n "$check" ]; then
     type plymouth > /dev/null 2>&1 && plymouth --hide-splash
     if [ -n "$DRACUT_SYSTEMD" ]; then
-        p=$(dev_unit_name "$livedev")
+        p=$(dev_unit_name "$check_dev")
         systemctl start checkisomd5@"${p}".service
     else
-        checkisomd5 --verbose "$livedev"
+        checkisomd5 --verbose "$check_dev"
     fi
     if [ $? -eq 1 ]; then
         die "CD check failed!"

modules.d/90dmsquash-live/module-setup.sh

@@ -22,7 +22,7 @@ installkernel() {
 
 # called by dracut
 install() {
-    inst_multiple umount dmsetup blkid dd losetup blockdev find rmdir
+    inst_multiple umount dmsetup blkid dd losetup blockdev find rmdir grep
     inst_multiple -o checkisomd5
     inst_hook cmdline 30 "$moddir/parse-dmsquash-live.sh"
     inst_hook cmdline 31 "$moddir/parse-iso-scan.sh"