1#!/bin/bash
2
3function usage {
4  echo "Usage: prepare_image image_type kernel_image rootfs_image header_size"
5  echo "Padd root and kernel image to the correct size and append the jffs2 start marker as needed"
6  exit 1
7}
8
9function pad_file {
10	echo "Padding $1 to size $2"
11	dd if=$1 of=$1.paddingtempfile bs=$2 count=1 conv=sync &> /dev/null
12	mv $1.paddingtempfile $1
13}
14
15#filesize filestart padding
16function calc_pad {
17	[  $((($1 + $2) & ($3 - 1))) == 0 ] && {
18		echo $1
19		return 0
20        }
21	echo $(((($1 + $2) | ($3 - 1)) + 1 - $2))
22}
23
24function prep_squash {
25	echo "kernel_size: $kernel_size"
26	echo "header_size: $header_size"
27	kernel_pad_size=$(calc_pad $kernel_size $header_size 32)
28	kernel_end=$(($header_size + $kernel_pad_size))
29	pad_file $kernel_image $kernel_pad_size
30
31	#4k
32	rootfs_pad_size=$(calc_pad $rootfs_size $kernel_end 4096)
33	pad_file $rootfs_image $rootfs_pad_size
34	echo -ne '\xde\xad\xc0\xde' >> $rootfs_image
35	
36	#8k
37	rootfs_pad_size=$(calc_pad $rootfs_size $kernel_end 8192)
38	[ $rootfs_pad_size == rootfs_old_padsize ] || {
39		pad_file $rootfs_image $rootfs_pad_size
40		rootfs_old_padsize=$rootfs_pad_size
41		echo -ne '\xde\xad\xc0\xde' >> $rootfs_image
42	}
43
44	#64k
45	rootfs_pad_size=$(calc_pad $rootfs_size $kernel_end 65536)
46	[ $rootfs_pad_size == rootfs_old_padsize ] || {
47		pad_file $rootfs_image $rootfs_pad_size
48		rootfs_old_padsize=$rootfs_pad_size
49		echo -ne '\xde\xad\xc0\xde' >> $rootfs_image
50	}
51
52	#128k
53	rootfs_pad_size=$(calc_pad $rootfs_size $kernel_end 131072)
54	[ $rootfs_pad_size == rootfs_old_padsize ] || {
55		pad_file $rootfs_image $rootfs_pad_size
56		rootfs_old_padsize=$rootfs_pad_size
57		echo -ne '\xde\xad\xc0\xde' >> $rootfs_image
58	}
59	
60}
61
62function prep_jffs2 {
63	kernel_pad_size=$(calc_pad $kernel_size $header_size $1)
64	pad_file $kernel_image $kernel_pad_size
65}
66
67image_type=$1
68kernel_image=$2
69rootfs_image=$3
70header_size=$4
71
72if [ -z "$image_type" ] || [ -z "$rootfs_image" ] || [ -z "$kernel_image" ] || [ -z "$header_size" ]; then
73	usage
74fi
75
76if [ ! -e "$rootfs_image" ] || [ -z "$kernel_image" ]; then
77	echo "input file not found"
78	exit 1
79fi
80
81kernel_size=$(stat -c "%s" "$kernel_image")
82rootfs_size=$(stat -c "%s" "$rootfs_image")
83
84if [ $kernel_size == 0 ] || [ $rootfs_size == 0 ]; then
85	echo "kernel or rootfs empty"
86	exit 1
87fi
88
89case $image_type in
90	squashfs )
91		prep_squash ;;
92	jffs2-64k )
93		prep_jffs2 65536 ;;
94	jffs2-128k )
95		prep_jffs2 131072 ;;
96	* )
97		echo "Unknown image type"
98		exit 1 ;;
99esac
100
101