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5.0 2.0 0.0 265 KB

Manage file formats in pythonic way

Python 97.46% Assembly 2.00% Makefile 0.34% C 0.20%

abstruct's Introduction

Abstruct

The struct module on steroid.

This is a work in progress!!

I want to create a module able to pack()/unpack() generic file format described by using standard python classes syntax (the inspiration come from the way Django models work).

This because I need a module ables to not only to read but also to modify and to write ELF files and it seems that there are not module for this.

The API will be change very heavily in future, I'm in the design phase. It uses python3.

Roadmap

Example

This below is an example for an ELF header

from abstruct.core import Chunk
from abstruct import fields
from abstruct.executables.elf import fields as elf_fields
from abstruct.executables.elf.enum import (
    ElfEIClass,
    ElfEIData,
    ElfOsABI,
    ElfType,
    ElfMachine,
    ElfVersion,
)


class ElfIdent(Chunk):
    EI_MAG0 = fields.StructField('c', default=b'\x7f')
    EI_MAG1 = fields.StructField('c', default=b'E')
    EI_MAG2    = fields.StructField('c', default=b'L')
    EI_MAG3    = fields.StructField('c', default=b'F')
    EI_CLASS   = fields.StructField('B', enum=ElfEIClass, default=ElfEIClass.ELFCLASS32)  # determines the architecture
    EI_DATA    = fields.StructField('B', enum=ElfEIData, default=ElfEIData.ELFDATA2LSB)  # determines the endianess of the binary data
    EI_VERSION = fields.StructField('B', default=1)  # always 1
    EI_OSABI   = fields.StructField('B', enum=ElfOsABI, default=ElfOsABI.ELFOSABI_GNU)
    EI_ABIVERSION = fields.StructField('B')
    EI_PAD     = fields.StringField(7)


class ElfHeader(Chunk):
    e_ident     = fields.ElfIdentField()
    e_type      = elf_fields.Elf_Half(enum=ElfType, default=ElfType.ET_EXEC)
    e_machine   = elf_fields.Elf_Half(enum=ElfMachine, default=ElfMachine.EM_386)
    e_version   = elf_fields.Elf_Word(enum=ElfVersion, default=ElfVersion.EV_CURRENT)
    e_entry     = elf_fields.Elf_Addr()
    e_phoff     = elf_fields.Elf_Off()
    e_shoff     = elf_fields.Elf_Off()
    e_flags     = elf_fields.Elf_Word()
    e_ehsize    = elf_fields.Elf_Half(equals_to=Dependency('size'))
    e_phentsize = elf_fields.Elf_Half()
    e_phnum     = elf_fields.Elf_Half()
    e_shentsize = elf_fields.Elf_Half()
    e_shnum     = elf_fields.Elf_Half()
    e_shstrndx  = elf_fields.Elf_Half()


header = ElfHeader('/bin/ls')
print(header.e_entry.value) # will print the value associated with the field

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