# Copyright 2018 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import os
import subprocess

from whitelist import is_whitelisted

def check_debug_info(dso_path, readelf_content):
    """check whether debug info section exists in the elf file.

    Args:
        readelf: debug info dumped by command readelf

    Returns:
        True if debug info section exists, otherwise False.
    """

    # Return True if it is whitelisted
    if is_whitelisted('exist_debug_info', dso_path):
        return True

    for l in readelf_content:
        if 'debug_info' in l:
          return True
    return False

def check_producer(dso_path, readelf_content):
    """check whether DW_AT_producer exists in each compile unit.

    Args:
        readelf: debug info dumped by command readelf

    Returns:
        True if DW_AT_producer exists in each compile unit, otherwise False.
        Notice: If no compile unit in DSO, also return True.
    """

    # Return True if it is whitelisted
    if is_whitelisted('exist_producer', dso_path):
        return True

    # Indicate if there is a producer under each cu
    cur_producer = False

    first_cu = True
    producer_exist = True

    for l in readelf_content:
        if 'DW_TAG_compile_unit' in l:
            if not first_cu and not cur_producer:
                producer_exist = False
                break
            first_cu = False
            cur_producer = False
        elif 'DW_AT_producer' in l:
            cur_producer = True

    # Check whether last producer of compile unit exists in the elf,
    # also return True if no cu in the DSO.
    if not first_cu and not cur_producer:
        producer_exist = False

    return producer_exist

def check_exist_all(dso_path):
    """check whether intended components exists in the given dso.

    Args:
        dso_path: path to the dso
    Return:
        True if everything looks fine otherwise False.
    """

    readelf = subprocess.Popen(['readelf', '--debug-dump=info',
                                '--dwarf-depth=1', dso_path],
                                stdout=subprocess.PIPE,
                                stderr=open(os.devnull, 'w'))
    readelf_content = list(readelf.stdout)

    exist_checks = [check_debug_info, check_producer]

    for e in exist_checks:
        if not e(dso_path, readelf_content):
            check_failed = e.__module__ + ': ' + e.__name__
            print('%s failed check: %s' % (dso_path, check_failed))
            return False

    return True