Re: Suggest a tool for decoding binary data
On Sun, Feb 2, 2014 at 1:28 AM, Chen Wei <weichen302@icloud.com> wrote:
> On Sat, Feb 01, 2014 at 05:36:19PM -0800, Kevin O'Gorman wrote:
>> I'm about to tackle GPT partitioned disks, and want to decode the
>> label.
>>
>> The data is little-endian, but I want my code to work on little- or
>> big-endian machines. I want it to be a script -- nothing compiled.
>>
>> I've figured out that on my little-endian machines, I can use bash
>> with something like
>> otherlabel=$(($(dd if=label bs=1 skip=32 count=8 | od -An -t d8) ))
>
>
> I am not quit understand why need dump the label, but it can be done
> easily by script language, say, Python.
>
>
> # --------- begin --------------
> #!/usr/bin/env python
> # -*- coding: utf-8 -*-
>
> import sys
> from struct import unpack
>
> skip = 32
> count = 8
> fp = open(path_to_dd_image, 'rb').read(skip + count)
> data_of_interest = fp[skip:]
>
> if sys.byteorder == 'little':
> #assuming the label is a 8 bytes unsigned integer
> label = unpack('<Q', data_of_interest)[0]
> else:
> label = unpack('>Q', data_of_interest)[0]
> # --------- end --------------
Ah, thank you, that is a nice start. I'll remove the test for system
byteorder because the data is always little-endian. It's the sytem I
was worred about and the '<' is the ticket.
--
Kevin O'Gorman
programmer, n. an organism that transmutes caffeine into software.
Please consider the environment before printing this email.
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