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July 17, 2011 16:19
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#!/usr/bin/perl | |
###################################################################### | |
# | |
# File : split_bootimg.pl | |
# Author(s) : William Enck <enck@cse.psu.edu> | |
# Description : Split appart an Android boot image created | |
# with mkbootimg. The format can be found in | |
# android-src/system/core/mkbootimg/bootimg.h | |
# | |
# Thanks to alansj on xda-developers.com for | |
# identifying the format in bootimg.h and | |
# describing initial instructions for splitting | |
# the boot.img file. | |
# | |
# Last Modified : Tue Dec 2 23:36:25 EST 2008 | |
# By : William Enck <enck@cse.psu.edu> | |
# | |
# Copyright (c) 2008 William Enck | |
# | |
###################################################################### | |
use strict; | |
use warnings; | |
# Turn on print flushing | |
$|++; | |
###################################################################### | |
## Global Variables and Constants | |
my $SCRIPT = __FILE__; | |
my $IMAGE_FN = undef; | |
# Constants (from bootimg.h) | |
use constant BOOT_MAGIC => 'ANDROID!'; | |
use constant BOOT_MAGIC_SIZE => 8; | |
use constant BOOT_NAME_SIZE => 16; | |
use constant BOOT_ARGS_SIZE => 512; | |
# Unsigned integers are 4 bytes | |
use constant UNSIGNED_SIZE => 4; | |
# Parsed Values | |
my $PAGE_SIZE = undef; | |
my $KERNEL_SIZE = undef; | |
my $RAMDISK_SIZE = undef; | |
my $SECOND_SIZE = undef; | |
###################################################################### | |
## Main Code | |
&parse_cmdline(); | |
&parse_header($IMAGE_FN); | |
=format (from bootimg.h) | |
** +-----------------+ | |
** | boot header | 1 page | |
** +-----------------+ | |
** | kernel | n pages | |
** +-----------------+ | |
** | ramdisk | m pages | |
** +-----------------+ | |
** | second stage | o pages | |
** +-----------------+ | |
** | |
** n = (kernel_size + page_size - 1) / page_size | |
** m = (ramdisk_size + page_size - 1) / page_size | |
** o = (second_size + page_size - 1) / page_size | |
=cut | |
my $n = int(($KERNEL_SIZE + $PAGE_SIZE - 1) / $PAGE_SIZE); | |
my $m = int(($RAMDISK_SIZE + $PAGE_SIZE - 1) / $PAGE_SIZE); | |
my $o = int(($SECOND_SIZE + $PAGE_SIZE - 1) / $PAGE_SIZE); | |
my $k_offset = $PAGE_SIZE; | |
my $r_offset = $k_offset + ($n * $PAGE_SIZE); | |
my $s_offset = $r_offset + ($m * $PAGE_SIZE); | |
(my $base = $IMAGE_FN) =~ s/.*\/(.*)$/$1/; | |
my $k_file = $base . "-kernel"; | |
my $r_file = $base . "-ramdisk.gz"; | |
my $s_file = $base . "-second.gz"; | |
# The kernel is always there | |
print "Writing $k_file ..."; | |
&dump_file($IMAGE_FN, $k_file, $k_offset, $KERNEL_SIZE); | |
print " complete.\n"; | |
# The ramdisk is always there | |
print "Writing $r_file ..."; | |
&dump_file($IMAGE_FN, $r_file, $r_offset, $RAMDISK_SIZE); | |
print " complete.\n"; | |
# The Second stage bootloader is optional | |
unless ($SECOND_SIZE == 0) { | |
print "Writing $s_file ..."; | |
&dump_file($IMAGE_FN, $s_file, $s_offset, $SECOND_SIZE); | |
print " complete.\n"; | |
} | |
###################################################################### | |
## Supporting Subroutines | |
=header_format (from bootimg.h) | |
struct boot_img_hdr | |
{ | |
unsigned char magic[BOOT_MAGIC_SIZE]; | |
unsigned kernel_size; /* size in bytes */ | |
unsigned kernel_addr; /* physical load addr */ | |
unsigned ramdisk_size; /* size in bytes */ | |
unsigned ramdisk_addr; /* physical load addr */ | |
unsigned second_size; /* size in bytes */ | |
unsigned second_addr; /* physical load addr */ | |
unsigned tags_addr; /* physical addr for kernel tags */ | |
unsigned page_size; /* flash page size we assume */ | |
unsigned unused[2]; /* future expansion: should be 0 */ | |
unsigned char name[BOOT_NAME_SIZE]; /* asciiz product name */ | |
unsigned char cmdline[BOOT_ARGS_SIZE]; | |
unsigned id[8]; /* timestamp / checksum / sha1 / etc */ | |
}; | |
=cut | |
sub parse_header { | |
my ($fn) = @_; | |
my $buf = undef; | |
open INF, $fn or die "Could not open $fn: $!\n"; | |
binmode INF; | |
# Read the Magic | |
read(INF, $buf, BOOT_MAGIC_SIZE); | |
unless ($buf eq BOOT_MAGIC) { | |
die "Android Magic not found in $fn. Giving up.\n"; | |
} | |
# Read kernel size and address (assume little-endian) | |
read(INF, $buf, UNSIGNED_SIZE * 2); | |
my ($k_size, $k_addr) = unpack("VV", $buf); | |
# Read ramdisk size and address (assume little-endian) | |
read(INF, $buf, UNSIGNED_SIZE * 2); | |
my ($r_size, $r_addr) = unpack("VV", $buf); | |
# Read second size and address (assume little-endian) | |
read(INF, $buf, UNSIGNED_SIZE * 2); | |
my ($s_size, $s_addr) = unpack("VV", $buf); | |
# Ignore tags_addr | |
read(INF, $buf, UNSIGNED_SIZE); | |
# get the page size (assume little-endian) | |
read(INF, $buf, UNSIGNED_SIZE); | |
my ($p_size) = unpack("V", $buf); | |
# Ignore unused | |
read(INF, $buf, UNSIGNED_SIZE * 2); | |
# Read the name (board name) | |
read(INF, $buf, BOOT_NAME_SIZE); | |
my $name = $buf; | |
# Read the command line | |
read(INF, $buf, BOOT_ARGS_SIZE); | |
my $cmdline = $buf; | |
# Ignore the id | |
read(INF, $buf, UNSIGNED_SIZE * 8); | |
# Close the file | |
close INF; | |
# Print important values | |
printf "Page size: %d (0x%08x)\n", $p_size, $p_size; | |
printf "Kernel size: %d (0x%08x)\n", $k_size, $k_size; | |
printf "Ramdisk size: %d (0x%08x)\n", $r_size, $r_size; | |
printf "Second size: %d (0x%08x)\n", $s_size, $s_size; | |
printf "Board name: $name\n"; | |
printf "Command line: $cmdline\n"; | |
# Save the values | |
$PAGE_SIZE = $p_size; | |
$KERNEL_SIZE = $k_size; | |
$RAMDISK_SIZE = $r_size; | |
$SECOND_SIZE = $s_size; | |
} | |
sub dump_file { | |
my ($infn, $outfn, $offset, $size) = @_; | |
my $buf = undef; | |
open INF, $infn or die "Could not open $infn: $!\n"; | |
open OUTF, ">$outfn" or die "Could not open $outfn: $!\n"; | |
binmode INF; | |
binmode OUTF; | |
seek(INF, $offset, 0) or die "Could not seek in $infn: $!\n"; | |
read(INF, $buf, $size) or die "Could not read $infn: $!\n"; | |
print OUTF $buf or die "Could not write $outfn: $!\n"; | |
close INF; | |
close OUTF; | |
} | |
###################################################################### | |
## Configuration Subroutines | |
sub parse_cmdline { | |
unless ($#ARGV == 0) { | |
die "Usage: $SCRIPT boot.img\n"; | |
} | |
$IMAGE_FN = $ARGV[0]; | |
} | |
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see my fork https://gist.github.com/JPT77/0a2fc46a8a9926734f52b82ec65197f7 for an update which adds the device tree partition