Update-grub does not set kopt correctly in loopinstallations

[Agostino Russo]

Binary package hint: grub

Update-grub does not set kopt correctly in loopinstallations, the following patch should improve the situation. This bug blocks https://blueprints.launchpad.net/ubuntu/+spec/installer-for-windows

300,311c300
< loop_file=$(awk '$2=="/" && $4~"loop" {print $1}' /etc/fstab)
< host_device=$(awk '"'${loop_file}'"~"^"$2 && $2!="/" {print $1}' /proc/mounts)
< host_mountpoint=$(awk '$1=="'${host_device}'" && $2!="/boot" {print $2}' /proc/mounts)
< loop_file=${loop_file#$host_mountpoint}
< if [ -n "$host_device" ]; then
< boot_device=
< root_device="$host_device"
< default_kopt="root=$host_device loop=$loop_file ro"
< else
< default_kopt="root=$root_device ro"
< fi
< kopt="$default_kopt"
---
> kopt="root=$(awk '$2 == "/" {print $1}' /etc/fstab) ro"
836c825
< kopt_2_6="$default_kopt"
---
> kopt_2_6="root=$root_device ro"

[Agostino Russo (ago)]

The patched file is available at:

http://codebrowse.launchpad.net/~ubuntu-installer/lupin/hardy/annotate/ago%40nbago-20071212234211-5cirxnh5zfkgqvzh?file_id=updategrub-20071021190150-hexwoe8fo26l1f9b-10

[Agostino Russo (ago)]

diff -u

--- /home/src/extern/grub-0.97/debian/update-grub 2007-10-09 21:52:49.000000000 +0100
+++ update-grub 2008-01-02 09:05:01.000000000 +0000
@@ -297,7 +297,18 @@
 crashdump="0"

 # Default kernel options, overidden by the kopt statement in the menufile.
-kopt="root=$(awk '$2 == "/" {print $1}' /etc/fstab) ro"
+loop_file=$(awk '$2=="/" && $4~"loop" {print $1}' /etc/fstab)
+host_device=$(awk '"'${loop_file}'"~"^"$2 && $2!="/" {print $1}' /proc/mounts)
+host_mountpoint=$(awk '$1=="'${host_device}'" && $2!="/boot" {print $2}' /proc/mounts)
+loop_file=${loop_file#$host_mountpoint}
+if [ -n "$host_device" ]; then
+ boot_device=
+ root_device="$host_device"
+ default_kopt="root=$host_device loop=$loop_file ro"
+else
+ default_kopt="root=$root_device ro"
+fi
+kopt="$default_kopt"

 # Title
 title=$(lsb_release --short --description 2>/dev/null) || title="Ubuntu"
@@ -822,7 +833,7 @@
 # Set the kernel 2.6 option only for fresh install (but convert it to
 # mount-by-UUID on upgrade)
 test -z "$kopt_2_6" && test -z "$(GetMenuOpt "kopt" "")" && \
- kopt_2_6="root=$root_device ro"
+ kopt_2_6="$default_kopt"
 test -n "$kopt_2_6" && kopt_2_6=$(convert_kopt_to_uuid "$kopt_2_6")

 # Extract the grub root

[Agostino Russo (ago)]

Note that when not on a loopinstallation, I am setting:

default_kopt="root=$root_device ro"

When in the original code it used to be

kopt="root=$(awk '$2 == "/" {print $1}' /etc/fstab) ro"

My understanding is that using $root_device is safer, since it comes from find_root_device which also parses fstab but is more robust than the awk command (+ handles LABEL and UUID).

Strangely enough kopt_2_6, differently from kopt, did already use $root_device as opposed to the awk code.

[Agostino Russo (ago)]

Safer code

loop_file=$(awk '$2=="/" && $4~"loop" {print $1}' /etc/fstab)
if [ -f "$loop_file" ]; then
    dev_mountpoint=$(awk '"'${loop_file}'"~"^"$2 && $2!="/" {print $1";"$2}' /proc/mounts|tail -n 1)
    host_device="${dev_mountpoint%;*}"
    host_mountpoint="${dev_mountpoint#*;}"
fi
if [ -n "$host_device" ]; then
    boot_device=
    root_device="$host_device"
    default_kopt="root=$host_device loop=${loop_file#$host_mountpoint} ro"
else
    default_kopt="root=$root_device ro"
fi
kopt="$default_kopt"

[Launchpad Janitor (janitor)]

This bug was fixed in the package grub - 0.97-29ubuntu6

---------------
grub (0.97-29ubuntu6) hardy; urgency=low

  * Set kopt correctly for loop installations (LP: #175772). Thanks
    Agostino Russo.

 -- Evan Dandrea <email address hidden> Fri, 18 Jan 2008 14:41:27 -0500

[Agostino Russo (ago)]

It is necessary to remove the check:

if [ -f "$loop_file" ]; then

Since when update-grub is run by grub-installer in a chrooted installation, /host is not accessible and hence the above block will always evaluate to false. The fact that finde_device > readlink fails and defaults to /dev/hda1 is irrelevant since root_device is overidden by the included patch.

[Agostino Russo (ago)]

better still:

- if [ -f "$loop_file" ]; then
+ if [ -n "$loop_file" ]; then

[Launchpad Janitor (janitor)]

This bug was fixed in the package grub - 0.97-29ubuntu13

---------------
grub (0.97-29ubuntu13) hardy; urgency=low

  * /host is not accessible when update-grub is run by grub-installer so
    the file test will always fail (LP: #175772). Thanks Agostino Russo.

 -- Evan Dandrea <email address hidden> Wed, 30 Jan 2008 09:11:41 -0500