Question

You are going to write a Python program that represents a command line version of a hexadecimal editor. This program will be similar to the Linux built-in command line hexadecimal editors such as xxd and hexdump. The program will first ask the user to enter the name of any file you want to read. Your program will then print the binary contents of the file into the standard output (screen). The output will be divided into three main sections: the offset values in decimal, sixteen space-separated hexadecimal bytes, followed by the same sixteen bytes but in ASCII value. The figure below shows an example of the first 48 bytes of an output, and the three different sections: 00000000 do 66 c1 ea 10 f7 76 la 86 d6 8a 56 40 8a el co 1.f....V....v@...] 00000016 ||e4 06 0a cc b8 01 02 cd 13 66 61 of 82 75 ff 81 |.........fa..u.. 00000032 | c3 00 02 66 40 49 75 94 c3 42 4f 4f 54 40 47 52 | ...f@u..BOOTMGR || offset Hexadecimal Values ASCII Values Notice that in the 2nd section there a space between the 8th and 9th byte. Each output line represents 16 bytes. The first column shows the decimal offset, where the first byte from the first line represents the oth byte; the second line starts with byte 16h and so on. The final section only shows the printable ASCII characters. These are the ASCII characters can be printed on the screen (usually they are the characters with ASCII values between 0x20 and Ox7EThe rest of the unprintable bytes are replaced by a period (.'). The following built-in Python functions will be useful in this situation: chr, hex, ord. More information about these functions can be found here: https://docs.python.org/3/library/functions.html

Please read this comment:

This is the only file given by my professor and so can you please help me to write a python program. You can use any test file and post the output with the code. The output might be different then above but please help me to get started with the PYTHON code. Thank you in advance

Answer 1

//USAGE hexdump.py [filename]

import sys

import os.path

def check_file_provided():

  # This method ensures a valid file was provided to the invoked script ##

  if (len(sys.argv) < 2):

    print("")

    print("Error - No file was provided")

    print("")

    print("Correct Usage:")

    print("python hexdump.py <file_to_dump>")

    print("")

    sys.exit(0)

  if not os.path.isfile(sys.argv[1]):

    print("")

    print("Error - The file provided does not exist")

    print("")

    sys.exit(0)

  

def read_bytes(filename, chunksize=8192):

  # This method returns the bytes of a provided file ##

  try:

    with open(filename, "rb") as f:

      while True:

        chunk = f.read(chunksize)

        if chunk:

          for b in chunk:

            yield b'%c' %b

        else:

          break

  except IOError:

    print("")

    print("Error - The file provided does not exist")

    print("")

    sys.exit(0)

        

def is_character_printable(s):

  ## This method returns true if a byte is a printable ascii character ##

  return all((c < 127) and (c >= 32) for c in s)

  

def print_headers():

  ## This method prints the headers at the top of our hex dump ##

  print("")

  

def validate_byte_as_printable(byte):

  ## Check if byte is a printable ascii character. If not replace with a '.' character ##

  if is_character_printable(byte):

    return byte.decode('ascii')

  else:

    return '.'

  

## main ##

check_file_provided()

memory_address = 0

ascii_string = ""

print_headers()

## Loop through the given file while printing the address, hex and ascii output ##

for byte in read_bytes(sys.argv[1]):

  ascii_string = ascii_string + validate_byte_as_printable(byte)

  if memory_address%16 == 0:

    print(format(memory_address, '06'),end=" "),

    print(byte.hex(),end=" "),

  elif memory_address%16 == 15:

    print(byte.hex(),end=" "),

    print("|" + ascii_string + "|")

    ascii_string = " "

  elif memory_address%16 == 8:

    print(byte.hex(),end="  "),

  else:

    print(byte.hex(),end=" "),

  memory_address = memory_address + 1