Easily decompile `.pyc` and `.py` files for the latest python version.

dispyc.py

####
# Easily decompile `.pyc` and `.py` files for the latest python version. 
# Basic structure taken from https://nedbatchelder.com/blog/200804/the_structure_of_pyc_files.html, fully updated and added functionality.
# Added complete disassembly: offsets, opcodes, opnames...
####

import dis, marshal, struct, sys, time, types, py_compile

def to_int(bytes):
    return struct.unpack("i",bytes)[0]

def bytes2str(byte_seq):
    str_seq = ''
    for b in byte_seq:
        print(" %X" % b,end="")
    return str_seq

def calc_hex_length(number):
    return len(hex(number)[2:])

def show_file(f):
    magic = struct.unpack(">i",f.read(4))[0]
    bitfield = to_int(f.read(4))

    if(bitfield != 0): exit("Cannot parse hash-based pyc")

    moddate = to_int(f.read(4))
    modtime = time.asctime(time.localtime(moddate))

    filesize = to_int(f.read(4))

    indent = '   '

    print("HEADER")
    print("%smagic        %X" % (indent, magic))
    print("%smoddate      %s" % (indent, modtime))
    print("%sfilesize     %X" % (indent, filesize))

    code = marshal.load(f)

    show_code(code)
    
def show_code(code, indent=''):
    indent += '   '
    
    if(code.co_name == "<module>"):
        print("FILE")

        print("%sfilename     %r" % (indent, code.co_filename))
        
        print("CODE")
        
        print("%sname         %r" % (indent, code.co_name))
        print("%sfirstlineno  %d" % (indent, code.co_firstlineno))
        print("%sargcount     %d" % (indent, code.co_argcount))
        print("%snlocals      %d" % (indent, code.co_nlocals))
        print("%sstacksize    %d" % (indent, code.co_stacksize))
        print("%sflags        %04x" % (indent, code.co_flags))

        print("%sdissassembly" % indent)
    else:
        print("%sdissassembly" % indent)
        pass

    additional_indent = " "
    ez = False
    prev_indent = 1

    for instr in dis.Bytecode(code):
        instructions_args = ""
        
        zero = ""

        if len(hex(instr.offset)[2:]) == 1:
            zero += "0"

        print("%s%s%X: " % (indent*2, zero ,instr.offset), end="")

        if(instr.argval != None):
            instructions_args = ""

            if isinstance(instr.argval, int):
                if(calc_hex_length(instr.opcode) == 1):
                    print("0%X" % instr.opcode,end="")
                else:
                    print("%X" % instr.opcode,end="")
                
                zero = ""

                if len(hex(instr.argval)[2:]) == 1:
                    zero += "0"

                if(calc_hex_length(instr.argval) > 2):
                    nibble_length =  calc_hex_length(instr.argval)
                    byte_length   = ( nibble_length + 1 ) // 2

                    print(" ",end="")
                    for byte in (instr.argval).to_bytes(byte_length, "big"):
                        zero = ""
                        if len(hex(byte)[2:]) == 1:
                            zero += "0"
                        print("%s%X " % (zero,byte), end="")

                    print("%s %s %s" % ( ( (prev_indent-byte_length)*"   "), instr.opname, instr.argval))    
                    continue
                else:
                    print(" %s%X " % (zero,instr.argval), end="")
                
                print("%s %s %s" % ( ( (prev_indent-1)*"   "), instr.opname, instr.argval))

            elif(isinstance(instr.argval, str)):
                print("%X" % instr.opcode,end="")

                instructions_args = bytes2str(instr.argval.encode())
                
                temp = len(instr.argval.encode())
                if(temp < prev_indent):
                    print(" %s %s %s" % ((prev_indent-temp)*"   ",instr.opname, instr.argval))
                else:
                    if(ez):
                        print(" %s %s %s" % (((temp-prev_indent))*"   ", instr.opname, instr.argval))
                        prev_indent = temp
                    else:
                        print(" %s %s %s" % ("", instr.opname, instr.argval))
                        prev_indent = temp
                        ez = True

            elif(type(instr.argval) == types.CodeType):
                print(" '%s' {" % instr.argval.co_name)
            
                show_code(instr.argval, indent+' ')
                
                print("%s}" % (indent*2))
            
            else:
                exit("%sfailure parsing instruction %s" % (indent, type(instr.argval)))
        else:
            zero = ""

            if(calc_hex_length(instr.opcode) == 1):
                    zero = "0"

            print("%s%X %s %s%s %s" % (zero, instr.opcode, instructions_args , (prev_indent)*"   ", instr.opname, instr.argval))

    print("%sconsts" % indent)
    # const var is a code object
    for const in code.co_consts:
        if type(const) == types.CodeType:
            print("%s '%s'{" % (indent*2,const.co_name))
            
            show_code(const, indent+' ')
            
            print("%s}," % (indent*2))
            pass
        else:
            print("   %s%r," % (indent, const))
    if(code.co_name == "<module>"):
        print("%snames    %r" % (indent, code.co_names))
        print("%svarnames %r" % (indent, code.co_varnames))
        print("%sfreevars %r" % (indent, code.co_freevars))
        print("%scellvars %r" % (indent, code.co_cellvars))
    else:
        print("%svarnames %r" % (indent, code.co_varnames))
        print("%sfreevars %r" % (indent, code.co_freevars))

def main(file_path):
    if(file_path.lower().endswith('.py')):
        dest_path = py_compile.compile(file_path)
    elif(file_path.lower().endswith('.py')):
        dest_path = file_path
    else:
        print("Usage: python dispyc.py .pyc/.py")

    with open(dest_path, "rb") as f:
        show_file(f)

main(sys.argv[1])