Script for easily backing up emuMMC partitions

emummc-backup.sh

#!/bin/bash
# written by modeco80 and BlockBuilder57

# interactive interface for inputting emuMMC partition
# used if device argument is ommited from the command line
# or if the device argument is invalid
get_partition() {
	local _result=$1
    # display connected disks
	sudo fdisk -l

	read -rp "Input the partition containing the emuMMC you wish to back up: " part

	if [ ! -b "$part" ]; then
		clear
		echo "'$part' does not exist or is not a partition."
		get_partition $_result
	fi

	eval $_result="$part"
}

# Disable splitting.
# Activated by -d | --disable-split.
bool_disable_split="n"

# Keep rawnand.
# Activated by -k | --keep-rawnand
bool_keep_rawnand="n"

# Default size. Can be customized with --custom-size.
# To calculate block size, do ((byte_count / 1024) / 1024) / 4.
size="7455"

# Backup filename.
backup_filename="emummc-backup-$(date +"%Y-%m-%d").tar.bz2"

if [ "$1" == "" ]; then
	# run without arguments; interactively ask the user for the partition
	get_partition "part"
else
	# janky option getter
	while true; do
   		case "$1" in

			-h|--help)
				echo -e "Usage:"
				echo -e "    $0 [-d|--disable-split] [--custom-size [SIZE]] [-k|-keep-rawnand] [-h|--help] [PARTITION]\n"
				echo -e "PARTITION is optional, the script will provide interactive way to input device if ommited.\n"
				echo -e "Options:"
				echo -e "\t-d | --disable-split - disable splitting 'rawnand.bin' (if SD card filesystem is not FAT32)"
				echo -e "\t--custom-size [SIZE] - dump [SIZE] blocks instead of default 7455 blocks."
				echo -e "\t\t\t\t\bTo calculate block count, do (([SIZE_IN_BYTES] / 1024) / 1024) / 4."
				echo -e "\t-k | --keep-rawnand  - Keep 'rawnand.bin' when splitting."
				echo -e "\t-h | --help - show this message"
				exit
			;;

			-d|--disable-split)
   	    		bool_disable_split="y"
			;;

			-k|--keep-rawnand)
   	    		bool_keep_rawnand="y"
			;;

			--custom-size)
				shift

				if [ "$1" == "" ]; then
					echo "error: Value required for --custom-size"
					exit 1
				else
					case $1 in
						''|*[!0-9]*) 
							echo "error: Value provided is not a number."
							exit 1
						;;
						*)
							size=$1
						;;
					esac
				fi
			;;
			*)
				# assume partition argument was found
				part=$1
				break
			;;
		esac
		shift
	done

	if [ "$part" == "" ]; then
		# no partition argument 
		get_partition "part"
	fi

	if [ ! -b "$part" ]; then
		# launch interactive partition getter
		echo "'$part' does not exist or is not a partition."
		get_partition "part"
	fi
fi

mkdir emummc-backup

pushd emummc-backup
	# grab raw partition
	echo "Reading in full partition..."
	sudo dd if=$part bs=512 status=progress of=part.bin

	# extract out fat32 stuff
	echo "Removing FAT32 header..."
	dd if=part.bin bs=512 skip=32768 status=progress of=data.bin

	# extract BOOT0 and BOOT1
	echo "Separating BOOT0 and BOOT1.."
	dd if=data.bin bs=4M count=1 status=progress of=BOOT0
	dd if=data.bin bs=4M count=1 skip=1 status=progress of=BOOT1

	# extract actual nand data
	echo "Separating rawnand.bin..."
	dd if=data.bin bs=4M skip=2 count=$size status=progress of=rawnand.bin
	
	# split nand data into parts
	if [ "$bool_disable_split" == "n" ]; then
		echo "Splitting rawnand.bin into seperate files...."
		split -b 2G -a 2 -d --verbose rawnand.bin rawnand.bin.
	fi

	# clean up the rest
	echo "Cleaning up...."
	sudo rm part.bin
	rm data.bin
	if [[ "$bool_disable_split" == "n" ]] && [[ "$bool_keep_rawnand" == "n" ]]; then 
		rm rawnand.bin
	fi
popd

echo "Creating tar.bz2 archive of backup..."
BZIP2=-9 tar cjvf $backup_filename emummc-backup/*

rm -rvf backup/
echo "Backup created at '$PWD/$backup_filename'."