# ChangeFile -*- mode: python; coding: utf-8 -*-

# A class which represents a Debian change file.

# Copyright (c) 2002 Colin Walters <walters@gnu.org>

# This file 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 2 of the License, or
# (at your option) any later version.
#
# This program 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 this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

import os, re, stat
import logging
from .DpkgControl import *
from .SignedFile import *
from . import misc

class ChangeFileException(Exception):
    def __init__(self, value):
        self._value = value
    def __str__(self):
        return repr(self._value)

class ChangeFile(DpkgParagraph):
    md5_re = r'^(?P<hashsum>[0-9a-f]{32})[ \t]+(?P<size>\d+)[ \t]+(?P<section>[-/a-zA-Z0-9]+)[ \t]+(?P<priority>[-a-zA-Z0-9]+)[ \t]+(?P<file>[0-9a-zA-Z][-+:.,=~0-9a-zA-Z_]+)$'
    sha1_re = r'^(?P<hashsum>[0-9a-f]{40})[ \t]+(?P<size>\d+)[ \t]+(?P<file>[0-9a-zA-Z][-+:.,=~0-9a-zA-Z_]+)$'
    sha256_re = r'^(?P<hashsum>[0-9a-f]{64})[ \t]+(?P<size>\d+)[ \t]+(?P<file>[0-9a-zA-Z][-+:.,=~0-9a-zA-Z_]+)$'

    def __init__(self):
        DpkgParagraph.__init__(self)
        self._logger = logging.getLogger("mini-dinstall")
        self._file = ''

    def load_from_file(self, filename):
        self._file = filename
        f = SignedFile(open(self._file))
        self.load(f)
        f.close()

    def getFiles(self):
        return self._get_checksum_from_changes()['md5']

    def _get_checksum_from_changes(self):
        """ extract checksums and size from changes file """
        output = {}
        hashes = {
            'md5': ['files', re.compile(self.md5_re)],
            'sha1': ['checksums-sha1', re.compile(self.sha1_re)],
            'sha256': ['checksums-sha256', re.compile(self.sha256_re)]
        }

        if 'files' not in self:
            return []

        for (hash, (field, regex)) in list(hashes.items()):
            if field not in self:
                self._logger.warn("Can't find %s checksum in changes file '%s'" % (hash, os.path.basename(self._file)))
                continue
            output[hash] = []
            for line in self[field].splitlines():
                if not line:
                    continue
                match = regex.match(line)
                if not match:
                    raise ChangeFileException("Couldn't parse file entry \"%s\" in %s field of .changes" % (line, self.trueFieldCasing[field]))
                output[hash].append([match.group('hashsum'), match.group('size'), match.group('file')])
        return output

    def verify(self, sourcedir):
        """ verify size and hash values from changes file """
        checksum = self._get_checksum_from_changes()
        for (hash, value) in list(checksum.items()):
            for (hashsum, size, filename) in value:
                self._verify_file_integrity(os.path.join(sourcedir, filename), int(size), hash, hashsum)

    def _verify_file_integrity(self, filename, expected_size, hash, expected_hashsum):
        """ check uploaded file integrity """
        self._logger.debug('Checking integrity of %s' % filename)
        try:
            statbuf = os.stat(filename)
            if not stat.S_ISREG(statbuf[stat.ST_MODE]):
                raise ChangeFileException("%s is not a regular file" % filename)
            size = statbuf[stat.ST_SIZE]
        except OSError as e:
            raise ChangeFileException("Can't stat %s: %s" % (filename, e.strerror))
        if size != expected_size:
            raise ChangeFileException("File size for %s does not match that specified in .dsc" % filename)
        if misc.get_file_sum(self, hash, filename) != expected_hashsum:
            raise ChangeFileException("%ssum for %s does not match that specified in .dsc" % (hash, filename))
        self._logger.debug('Verified %ssum %s and size %s for %s' % (hash, expected_hashsum, expected_size, filename))

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