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Full Discussion: Extract sequences of bytes from binary for differents blocks
Top Forums Shell Programming and Scripting Extract sequences of bytes from binary for differents blocks Post 302845007 by wisecracker on Tuesday 20th of August 2013 02:36:12 PM
Old 08-20-2013
This is a starter Python 3.3.x code to extract the blocks using a user function...

This should be more than enough to get you going with your binary manipulation.

Once each block is placed into its respective _variable_ it is seriously easy to extract sub-blocks of data from each major block extracted from the binary file...
Code:
# BinarySearch.py
# DEMO to extract binary data...
# Written in such a way as to be easily understood.
# NOTE:- There are more Pythonic ways to do this...

import os
import sys

# The _variable_ used to test with...
block_one=b"?"
block_two=b"?"
subscript_begin=0

# Set to a _temporary_ directory. NOTE:- 4 different platforms shown...
# Change to suit your platform and path
if sys.platform=="linux2": os.chdir("/tmp/")
if sys.platform=="darwin": os.chdir("/Users/barrywalker/")
if sys.platform=="win32": os.chdir("C:\\Windows\\Temp\\")
if sys.platform=="amiga": os.chdir("T:")

# A basic "bin_extract()" function to extract binary data from a binary file...
def bin_extract(subscript_start=0, subscript_end=0, filename="?", char_start=b"\x00\xFF", char_end=b"\xFF\x00"):
	bin_var=b""
	toggle=0
	binfile=open(filename, "rb")
	for position in range(subscript_start, subscript_end, 1):
		binfile.seek(position)
		if binfile.read(2)==char_start:
			bin_var=bin_var+char_start[1:2]
			toggle=1
		if toggle>=1: bin_var=bin_var+binfile.read(1)
		if binfile.read(2)==char_end:
			bin_var=bin_var+char_end[0:1]
			toggle=0
			break
	binfile.close()
	return(bin_var, position)

# Test...
# ******** Do the first iteration and find the first block... *******
block_one, subscript_begin=bin_extract(0, 816, "BinaryFile", b"\xFF\x32", b"\xFF\x34")
print(block_one)
print(subscript_begin)
# When successful..........
# Just extract the required data from the _variable_ "new_binary" using standard simple Python methods
# and when finished with set new values to the function for the next block run using "subscript_begin"
# + or - 2 as the next "subscript_start" in the function, something like below...
block_two, subscript_begin=bin_extract((subscript_begin+2), 816, "BinaryFile", b"\xFF\x32", b"\xFF\x34")
print(block_two)
print(subscript_begin)
# DEMO end...

Hope this helps.
CYA.
 

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LEARN ABOUT DEBIAN

platform::shell

platform::shell(3tcl)					       Tcl Bundled Packages					     platform::shell(3tcl)

__________________________________________________________________________________________________________________________________________________

NAME

       platform::shell - System identification support code and utilities

SYNOPSIS

       package require platform::shell ?1.1.4?

       platform::shell::generic shell
       platform::shell::identify shell
       platform::shell::platform shell
_________________________________________________________________

DESCRIPTION

       The platform::shell package provides several utility commands useful for the identification of the architecture of a specific Tcl shell.

       This  package  allows the identification of the architecture of a specific Tcl shell different from the shell running the package. The only
       requirement is that the other shell (identified by its path), is actually executable on the current machine.

       While for most platform this means that the architecture of the interrogated shell is identical to the architecture of  the  running  shell
       this  is  not generally true. A counter example are all platforms which have 32 and 64 bit variants and where a 64bit system is able to run
       32bit code. For these running and interrogated shell may have different 32/64 bit settings and thus different identifiers.

       For applications like a code repository it is important to identify the architecture of the shell which will  actually  run  the  installed
       packages, versus the architecture of the shell running the repository software.

COMMANDS

       platform::shell::identify shell
	      This command does the same identification as platform::identify, for the specified Tcl shell, in contrast to the running shell.

       platform::shell::generic shell
	      This command does the same identification as platform::generic, for the specified Tcl shell, in contrast to the running shell.

       platform::shell::platform shell
	      This command returns the contents of tcl_platform(platform) for the specified Tcl shell.

KEYWORDS

       operating system, cpu architecture, platform, architecture

platform::shell 						       1.1.4						     platform::shell(3tcl)
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