grub-btrfs/41_snapshots-btrfs

#! /usr/bin/bash
#
#
#########################################################################################################################################
# Written by: Antynea															#
#																	#
# Purpose: Include btrfs snapshots at boot options.											#
#																	#
# What this script does:														#
# - List snapshots existing on root partition (btrfs).											#
# - Create corresponding menuentry in grub.cfg , which ensures a very easy rollback.							#
#																	#
# How to use it:															#
# - Add this lines to /etc/default/grub:												#
#																	#
# * GRUB_BTRFS_SUBMENUNAME="ArchLinux Snapshots" 					(Name menu appearing in grub.)	 		#
# * GRUB_BTRFS_PREFIXENTRY="Snapshot"        		   				(Add a name ahead your snapshots entries.)	#
# * GRUB_BTRFS_NKERNEL=("vmlinuz-linux") 		 				(Custom Name kernel you use it.) 		#
# * GRUB_BTRFS_NINIT=("initramfs-linux.img" "initramfs-linux-fallback.img")		(Custom Name initramfs (ramdisk) you use it.)	#
# * GRUB_BTRFS_INTEL_UCODE=("intel-ucode.img") 						(Custom Name intel microcode you use it.)	#
#																	#
# - Generate grub.cfg (on Archlinux use grub-mkconfig -o /boot/grub/grub.cfg )								#
#																	#
# - grub-btrfs automatically generates snapshots entries.										#
# - You will see it appear different entries, e.g : Prefixentry name of snapshot [2013-02-11 04:00:00]					#
#																	#
# Warning:																#
# This version detect kernels,initramfs,intel microcode only in boot partition, not in snapshot.					#
# If those that are present in boot partition but not in snapshot,								   	#
# entry will be created but not fonctional, you don't boot it.										#
#																	#
#########################################################################################################################################
set -e

. /usr/share/grub/grub-mkconfig_lib
. /etc/default/grub

######################################
### variables in /etc/default/grub ###
######################################
## Submenu name
submenuname=${GRUB_BTRFS_SUBMENUNAME:-"ArchLinux Snapshots"}
## Prefix entry
prefixentry=${GRUB_BTRFS_PREFIXENTRY:-"Snapshot"}
## Kernel(s) name(s)
nkernel=("${GRUB_BTRFS_NKERNEL[@]:-vmlinuz-linux}")
## Initramfs name(s)
ninit=("${GRUB_BTRFS_NINIT[@]:-initramfs-linux.img initramfs-linux-fallback.img}")
## Intel-ucode name(s)
intel_ucode=("${GRUB_BTRFS_INTEL_UCODE[@]:-intel-ucode.img}")

########################
### variables script ###
########################
## Internationalization (default : english)
export TEXTDOMAIN=grub-btrfs-git
export TEXTDOMAINDIR="/usr/share/locale"
## hints string
pboot=$(${grub_probe} --target="hints_string" "/boot" 2>/dev/null)
## UUID of the root partition
uuid=$(${grub_probe} "/" --target="fs_uuid" 2>/dev/null)
## UUID of the boot partition
buuid=$(${grub_probe} --target="fs_uuid" "/boot" 2>/dev/null)
## Parameters passed to the kernel
params="$GRUB_CMDLINE_LINUX $GRUB_CMDLINE_LINUX_DEFAULT"

##############
### Script ###
##############

typeset -A date_time
unset snapshots

# Create list of filesystem snapshots
oldIFS=$IFS
IFS=$'\n'

for snap in $($bindir/btrfs subvolume list -sa / --sort=-ogen | $bindir/awk '{gsub(/^.*<FS_TREE>\//,"",$NF);print $11" "$12"?"$NF}'); do
        snap_name="${snap#*"?"}"
        # Discard deleted snapshots
        if [ $snap_name = "DELETED" ]; then continue; fi
        snapshots+=("$snap_name")
        date_time[$snap_name]="${snap%"?"*}"
done
IFS=$oldIFS

# Display the menu
echo "submenu '$submenuname' {"

# Treat the kernel variables (Translation unclear)
for kernel in ${nkernel[@]}; do
	# Check the specified kernel(s) exist, if it/they don't, display an error and exit
	if [ ! -f /boot/$kernel ]; then gettext_printf $"Error: /boot/$kernel, kernel does not exist" >&2; exit 1; fi
	# If there are >1 kernels, create a menu
	if [ ${#nkernel[*]} != 1 ]; then echo "	submenu '$kernel' {
		submenu '---> Kernel: $kernel <---' { echo }"; fi
	# Treat the snapshots variable
	for item in ${snapshots[@]}; do
		# Output name of snapshot
		gettext_printf $"Found Snapshot: %s\n" "$item ${date_time[$item]}" >&2
		# Create a menu for remaining snapshots (name + creation date)
		echo "		submenu '$prefixentry $item [${date_time[$item]}]' {"
		# if more than one kernel is found, create a menu
		if [ ${#nkernel[*]} != 1 ]; then echo "			submenu '---> Kernel: $kernel <---' { echo }"; fi
		# Treat the initramfs variable
		for init in ${ninit[@]}; do
			# Check the specified initramfs(es) exist, if it/they don't, display an error and exit
			if [ ! -f /boot/$init ]; then gettext_printf $"Error: /boot/$init, initramfs does not exist" >&2; exit 1; fi
			# Specify a kernel and initramfs for every snapshot
			echo "\
			menuentry '$item $init' --class arch --class gnu-linux --class gnu --class os "\$menuentry_id_option" 'gnulinux-snapshots-$uuid'{
				load_video
				set gfxpayload=$GRUB_GFXPAYLOAD_LINUX
				if [ x"\$feature_platform_search_hint" = xy ]; then
					search --no-floppy --fs-uuid --set=root $pboot $buuid
				else
					search --no-floppy --fs-uuid --set=root $buuid
				fi
				echo	'Loading Linux snapshot ...'"
				# Check the location of the /boot partition
				if [ $uuid = $buuid ]; then
					echo "\
				linux	/$item/boot/$kernel root=UUID=$uuid rw rootflags=subvol=$item $params
				echo    'Loading initial ramdisk ...'"
				# Check intel microcode exist
					if [ -f /boot/$intel_ucode ]; then
						echo "\
				initrd	/$item/boot/$intel_ucode /$item/boot/$init"
					else
						echo "\
				initrd	/$item/boot/$init"
					fi
				else
					echo "\
				linux	/$kernel root=UUID=$uuid rw rootflags=subvol=$item $params
				echo    'Loading initial ramdisk ...'"
				# Check intel microcode exist
				if [ -f /boot/$intel_ucode ]; then
						echo "\
				initrd	/$intel_ucode /$init"
					else
						echo "\
				initrd  /$init"
					fi
				fi
				echo "\
			}"
		done
		echo "		}"
	done
	# Don't forget to close menus if more than one kernel is found
	if [ ${#nkernel[*]} != 1 ]; then echo "	}"; fi
done
echo "}"