Add git index file comparator.

from diffoscope.comparators.fsimage import FsImageFile

from diffoscope.comparators.fonts import TtfFile

from diffoscope.comparators.gettext import MoFile

from diffoscope.comparators.git import GitIndexFile

from diffoscope.comparators.gzip import GzipFile

from diffoscope.comparators.haskell import HiFile

from diffoscope.comparators.icc import IccFile

    MozillaZipFile,

    ImageFile,

    CbfsFile,

    GitIndexFile,

    )

# -*- coding: utf-8 -*-

#

# diffoscope: in-depth comparison of files, archives, and directories

#

# Copyright © 2016 Chris Lamb <lamby@debian.org>

#

# diffoscope is free software: you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation, either version 3 of the License, or

# (at your option) any later version.

#

# diffoscope is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with diffoscope.  If not, see <http://www.gnu.org/licenses/>.

import re

import os

import struct

import binascii

from diffoscope.difference import Difference

from diffoscope.comparators.binary import File

class GitIndexFile(File):

    RE_FILE_TYPE = re.compile(r'^Git index')

    @staticmethod

    def recognizes(file):

        return GitIndexFile.RE_FILE_TYPE.match(file.magic_file_type)

    def compare_details(self, other, source=None):

        return [Difference.from_text(

            describe_index(self.path),

            describe_index(other.path),

            self,

            other,

        )]

def parse_index(f):

    _, version = struct.unpack('>LL', f.read(4 * 2))

    return {

        'version': version,

        'entries': list(parse_entries(f)),

    }

def parse_entries(f):

    num_entries = struct.unpack('>L', f.read(4))[0]

    for _ in range(num_entries):

        x = {}

        pos = f.tell()

        x['ctime'], x['ctime_nano'], x['mtime'], x['mtime_nano'], \

                x['dev'], x['inode'], x['mode'], x['uid'], x['gid'], \

                x['size'], x['sha'], x['flags'] = \

            struct.unpack('>LLLLLLLLLL20sH', f.read((4 * 10) + 20 + 2))

        x['path'] = f.read(x['flags'] & 0x0fff)

        f.read((pos + ((f.tell() - pos + 8) & ~7)) - f.tell())

        yield x

def describe_index(filename):

    with open(filename, 'rb') as f:

        index = parse_index(f)

    return """

Version: {version}

Entries:

{entries_fmt}

""".format(

    entries_fmt=''.join(describe_entry(x) for x in index['entries']),

    **index

)

def describe_entry(x):

    return """

Path:      {x[path]}

SHA:       {hexsha}

Size:      {x[size]}

Flags:     {x[flags]:#b}

User ID:   {x[uid]}

Group ID:  {x[gid]}

Created:   {x[ctime]}.{x[ctime_nano]}

Modified:  {x[mtime]}.{x[mtime_nano]}

Inode:     {x[inode]}

Device ID: ({major}, {minor})

""".format(

    x=x,

    major=os.major(x['dev']),

    minor=os.minor(x['dev']),

    hexsha=binascii.b2a_hex(x['sha']).decode('utf-8'),

)