#!/usr/bin/python
# vim: set fileencoding=utf-8 :
#
# (C) 2011 Guido Guenther <agx@sigxcpu.org>
#     2011 Christoph Göhre <chris@sigxcpu.org>
#
#    This program is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program; if not, write to the Free Software
#    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
# Extract kernel and initramfs from a tip22 ECOFF boot image

import re
import subprocess
import sys

from optparse import OptionParser

OBJDUMP="/usr/bin/objdump"
BLOCKSIZE=4096

def extract_blob(binary, vma, offset, start, end, out):
    fs = offset + start - vma
    length = end - start

    b = file(binary, 'rb')
    o = file(out, 'wb')
    b.seek(fs)

    print "In: %s, length: %d, out: %s" % (binary, length, out)
    while length > 0:
        l = [length, BLOCKSIZE][length > BLOCKSIZE]
        data = b.read(l)
        o.write(data)
        length -= BLOCKSIZE

    b.close()
    o.close()


def parse_objdump_headers(image):
    """Determine vma and offset"""
    segment_re = re.compile(".* \.data\s+[0-9a-f]{8}\s+(?P<vma>[0-9a-f]{8})\s+[0-9a-f]{8}\s+(?P<offset>[0-9a-f]{8})\s+")
    vma, offset = None, None

    output = subprocess.Popen([OBJDUMP, "-h", image], stdout=subprocess.PIPE).stdout
    for line in output:
        m = segment_re.match(line)
        if m:
            vma = int(m.group("vma"), 16)
            offset = int(m.group("offset"), 16)
            break
    return (vma, offset)


def parse_objdump_symbols(image):
    """Determine kernel and initrd start and end, vma and offset"""

    symbol_re = re.compile(".* [a-z] (?P<addr>[a-f0-9]{16}) .* (?P<name>__[a-z]+_(start|end))")
    symbols = { "__rd_start": None,
                "__rd_end": None,
                "__kernel_start": None,
                "__kernel_end": None, }

    output = subprocess.Popen([OBJDUMP, "-t", image], stdout=subprocess.PIPE).stdout
    for line in output:
        m = symbol_re.match(line)
        if m:
            name = m.group("name")
            if name in symbols:
                symbols[name] = int(m.group("addr"), 16)
            continue
    return symbols


def main(argv):
    usage = """%prog <tip22image>

%prog extracts kernel and initramfs out of a tip22 image and stores the them in
files named 'kernel.img' and 'initrd.img' respectively"""

    parser = OptionParser(usage)
    options, args = parser.parse_args(argv[1:])
    if len(args) != 1:
        parser.print_usage()
        return 1
    else:
        image = args[0]

    vma, offset = parse_objdump_headers(image)
    if not vma or not offset:
        print >>sys.stderr, "Couldn't parse headers."
        return 1

    symbols = parse_objdump_symbols(image)

    print "vma: 0x%x, offset: 0x%x" % (vma, offset)
    print ("__kernel_start: 0x%(__kernel_start)x\n"
           "__kernel_end:   0x%(__kernel_end)x\n"
           "__rd_start:     0x%(__rd_start)x\n"
           "__rd_end:       0x%(__rd_end)x" % symbols)

    extract_blob(image, vma, offset, symbols["__kernel_start"],
                                     symbols["__kernel_end"],
                                     "kernel.img")
    extract_blob(image, vma, offset, symbols["__rd_start"],
                                     symbols["__rd_end"],
                                     "initrd.img")
    return 0

if __name__ == '__main__':
    sys.exit(main(sys.argv))

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