mgalive: support persistence when isohybrid protective partition starts at sector 1

- origin:
  https://svnweb.mageia.org/packages/cauldron/dracut/current/SOURCES/0511-mgalive-A-module-to-mount-Mageia-Live-media.patch?r1=1326566&r2=1329441
- mgalive: support persistence when isohybrid protective partition starts at sector 1
- mgalive: fix boot when ISO is copied into USB stick partition (e.g. by Rufus)

2 files changed, 34 insertions, 9 deletions

diff --git a/modules.d/90mgalive/mgalive-root.sh b/modules.d/90mgalive/mgalive-root.sh
index 77a34bd..e0fd882 100755
--- a/modules.d/90mgalive/mgalive-root.sh
+++ b/modules.d/90mgalive/mgalive-root.sh
@@ -30,24 +30,48 @@ basedir=$(getarg mgalive.basedir)
 # stick may want to override this.
 overlay=$(getarg mgalive.overlay)
 if [ -z "$overlay" ] ; then
-    overlay=`blkid -t LABEL=mgalive-persist -o device | grep $basedev`
+    overlay=$(blkid -t LABEL=mgalive-persist -o device | grep $basedev)
 else
     overlay=$livedev$overlay
 fi
 
-if [ -z "$basedir" -a -z "$overlay" ] ; then
-    # Fix udev isohybrid LABEL issues (mga #3334)
-    # (things have moved on - this may not be needed now)
-    media=$basedev
-else
-    media=$livedev
-fi
-
 info "mgalive basedev is $basedev"
 info "mgalive livedev is $livedev"
 info "mgalive basedir is $basedir/"
 info "mgalive overlay is $overlay"
 
+media=$livedev
+if [ -z "$(blkid $livedev)" ] ; then
+    if strstr "$(blkid $basedev)" "iso9660" ; then
+        # This happens when we boot from a USB stick with a isohybrid partition
+        # scheme where the first sector is unclaimed, so the first partition starts
+        # at sector 1. The iso9660 filesystem starts at sector 0, so blkid doesn't
+        # detect a valid filesystem in the first partition. udev, however, links
+        # the entry in /dev/disk/by-label to the first partition, not to the raw
+        # device, and that is what we get passed in $1 (mga#3334).
+        if [ -n "$overlay" ] ; then
+            # If we mount the raw device, we can't then also mount a partition
+            # on that device. So to enable persistence, we need to extend the
+            # first partition to claim the full range  of the iso9660 filesystem.
+            ps=$(partx -go START $livedev)
+            pe=$(partx -go END   $livedev)
+            if [ $ps -eq 1 ] ; then
+                info "Extending $livedev to cover sector 0"
+                delpart $basedev 1
+                addpart $basedev 1 0 $pe
+            else
+                info "$livedev is not a valid protective partition"
+            fi
+        else
+            # If we don't have a persistent partition, take the easy option.
+            info "Using $basedev to mount the iso9660 filesystem"
+            media=$basedev
+        fi
+    else
+        info "$livedev does not contain a valid filesystem"
+    fi
+fi
+
 # Mount the live media
 mount -n -o ro $media /live/media
 
diff --git a/modules.d/90mgalive/module-setup.sh b/modules.d/90mgalive/module-setup.sh
index b8f3f8d..260f4e8 100755
--- a/modules.d/90mgalive/module-setup.sh
+++ b/modules.d/90mgalive/module-setup.sh
@@ -16,6 +16,7 @@ installkernel() {
 
 install() {
     inst_multiple blkid clear eject grep losetup umount
+    inst_multiple addpart delpart partx
 
     inst_hook cmdline 30 "$moddir/mgalive-parse.sh"
     inst_hook pre-udev 30 "$moddir/mgalive-genrules.sh"