#!/usr/bin/env python

import os
from glob import glob
import tarfile

from elftools.elf.elffile import ELFFile

valid_dirs = ['usr/bin/', 'usr/sbin/']


def _file_has_magic(fileobj, magic_bytes):
    length = len(magic_bytes)
    magic = fileobj.read(length)
    fileobj.seek(0)
    return magic == magic_bytes


def is_elf(fileobj):
    "Take file object, peek at the magic bytes to check if ELF file."
    return _file_has_magic(fileobj, b"\x7fELF")


def is_pie(fp):
    elf = ELFFile(fp)
    return elf.header['e_type'] == 'ET_DYN'


def check_tar(xzfile):
    with tarfile.open(xzfile) as tar:
        for entry in tar:
            if not entry.isfile():
                continue

            in_dir = any(entry.name.startswith(d) for d in valid_dirs)

            if not in_dir:
                continue

            fp = tar.extractfile(entry)
            if not is_elf(fp):
                continue

            elf = ELFFile(fp)
            if elf.header['e_type'] == 'ET_DYN':
                print('{}: PIE'.format(entry.name))
                return True
            else:
                print('{}: Cake is a lie!'.format(entry.name))
                return False

no_pie = []
files = glob('/srv/ftp/pool/packages/*.pkg.tar.xz')
for pkg in files:
    if not check_tar(pkg):
        no_pie.append(os.path.basename(pkg))

pie = len(files) - len(no_pie)
print('PIE stats {}/{}'.format(pie, len(files)))