parse_db.py

#!/usr/bin/python
import tarfile
from sys import argv
from os.path import dirname, basename

class TarFileWithDirs(tarfile.TarFile):
    def __init__(self, *args, **kwargs):
        super(TarFileWithDirs, self).__init__(*args, **kwargs)
        self._dirs = {}
        for o in self:
            self._append_to_dir(o)
    def _append_to_dir(self, o):
        basedir = dirname(o.name)
        if basedir not in self._dirs:
            self._dirs[basedir] = []
        if not o.name in self._dirs and o.isdir():
            self._dirs[o.name] = []
        self._dirs[basedir].append(o)

    def getmembers(self, name=None):
        if name is None:
            return super(TarFileWithDirs, self).getmembers()
        return self._dirs[name]

    def addfile(self, tarinfo, fileobj=None):
        super(TarFileWithDirs, self).addfile(tarinfo, fileobj)
        self._append_to_dir(tarinfo)


class DBReader(dict):
    def __init__(self, db_path):
        super(DBReader, self).__init__()
        tar = TarFileWithDirs.open(db_path)
        for o in tar:
            if o.isdir():
                self.append_pkg_to_tree(o, tar)
    def append_pkg_to_tree(self, o, tar):
        for m in tar.getmembers(o.name):
            if basename(m.name) == 'desc':
                pkg = DBReader.config_parser(tar.extractfile(m.name).read().decode())
                self[pkg['name']] = pkg
    @staticmethod
    def config_parser(string):
        lines = string.split('\n')
        o = {}
        i = 0
        param = ''
        while i < len(lines):
            line = lines[i]
            if line.startswith('%'):
                param = line[1:-1].lower() # Really we need cut-out value between %'s, so this is lazy implementation
                o[param] = []
            elif param and line == '':
                if len(o[param]) == 1:
                    o[param] = o[param][0]
                param = ''
            elif param:
                o[param].append(line)
            i += 1
        return o
# Test code
if __name__ == '__main__':
    dbreader = DBReader(argv[1])
    required_pkgs = argv[2:]
    i = 0
    for name, data in dbreader.items():
        if name in required_pkgs:
            if i > 0:
                print(' %s' % data['filename'], end='')
            else:
                print(data['filename'], end='')
            i += 1