bboard

import sys, glob, os, struct

#feed original filename, detect named subfiles, merge
def mergeIMF(filename):
    with open(filename, 'wb') as file:
        for i in range(1,11,1):
            subfilename = filename[0:8] + "_subfile_" + str(i) + filename[8:]
            print(subfilename, end="\t")
            if os.path.exists(subfilename):
                with open(subfilename, 'rb') as subfile:
                #get subfile size, do bitshift shit, little endian... or encode somehow? google it.
                #write to file in correct order
                #write bytes(size of subfile) of this subfile to file
                #close subfile
                    subfilesize = os.path.getsize(subfilename)
                    print(subfilesize, end="\t")
                    subfilesizebyte = struct.pack('<I', subfilesize)
                    print(subfilesizebyte)
                    subfile.close()
            else:
                pass
        file.close()

for arg in sys.argv[1:]:
    for files in glob.glob(arg):
        mergeIMF(files)

 python .\imf_merge.py .\IMF00A.IMG
.\IMF00A_subfile_1.IMG  80      b'P\x00\x00\x00'
.\IMF00A_subfile_2.IMG  64      b'@\x00\x00\x00'
.\IMF00A_subfile_3.IMG  124     b'|\x00\x00\x00'
.\IMF00A_subfile_4.IMG  16      b'\x10\x00\x00\x00'
.\IMF00A_subfile_5.IMG  1360    b'P\x05\x00\x00'
.\IMF00A_subfile_6.IMG  2084    b'$\x08\x00\x00'
.\IMF00A_subfile_7.IMG  78812   b'\xdc3\x01\x00'
.\IMF00A_subfile_8.IMG  1660    b'|\x06\x00\x00'
.\IMF00A_subfile_9.IMG  8156    b'\xdc\x1f\x00\x00'
.\IMF00A_subfile_10.IMG 4328    b'\xe8\x10\x00\x00'

Posted by funkyass
its not gonna escape printable characters.You might want to poke at string formatting.

to convert between the two you are just reversing the string byte by byte at the end of the day.

Very few processors use big-endian, so there actually isn't any need to fumble with the byte order, unless you need to muck about with low-level networking.

Posted by funkyass
you aren't printing a string representation of bytes, you are literally sending the bytes to stdout. stdout isn't equipped to show raw bytes. If you want the hex values for the bytes, you should look in python's string formatting.

Posted by Screwtape

Goal of this script right now is to print the file size of each subfile as a little endian byte string with a word size of 4 bytes. As you can see from the output, in all but 3 cases it's printing I think an ascii character for the first (least significant) byte instead of a byte string.

You are doing it exactly right.

In your script, the "subfilesizebyte" is a byte string of length 4, representing the file-size as a 32-bit little-endian integer.

However, most of the bytes in that byte-string do not map to human-readable characters in ASCII, so if you just "print(subfilesizebyte)" then Python will encode the byte-string in a human readable way.

Looking at subfile 5 in your example, the length is 1360 in decimal, or 0x00000550 as a 32-bit hexadecimal number. If we convert that to little-endian bytes, we get: 0x50, 0x05, 0x00, 0x00.

Python's byte-string syntax is designed to express bytes of any value, even ones that don't map to printable characters in ASCII. For example, you generally can't type a 0x00 byte on a keyboard, and even if you could it doesn't display as anything, so Python lets you encode that as the four bytes '\x00'. Python interprets that sequence as a single 0x00 byte, but it can safely be written in source-code and printed out without confusion.

So, in Python's byte-string syntax, we could write those four bytes as b'\x50\x05\x00\x00'. But since 0x50 is the ASCII code for 'P' we don't have to hex-encode the first byte to make it printable, we can just write b'P\x05\x00\x00' which is what your program outputs.

The question is - what did you *expect* to see?

Posted by Screwtape
I'm glad to hear you found a way to display integers that conforms to your unstated assumptions.