Revelation / src / lib / io.py

#
# Revelation 0.3.1 - a password manager for GNOME 2
# http://oss.codepoet.no/revelation/
# $Id$
#
# Module for IO-related functionality
#
#
# Copyright (c) 2003-2004 Erik Grinaker
#
# This program 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 revelation, gobject, os, os.path


class DetectError(Exception):
        "Error for failed filetype detection"



class DataFile(gobject.GObject):
        "Processes data files"

        def __init__(self, file = None, handler = revelation.datahandler.Revelation, password = None):
                gobject.GObject.__init__(self)

                self.file       = file
                self.password   = password
                self.handler    = None

                if handler is not None:
                        self.handler = handler()


        def check_file(self):
                "Checks if a file is valid for loading"

                if not file_exists(self.file):
                        raise IOError

                data = file_read(self.file, 4096)
                self.handler.check_data(data)


        def detect_type(self):
                "Attempts to find a suitable handler for the file"

                data = file_read(self.file, 4096)

                for handler in revelation.datahandler.get_import_handlers():
                        handler = handler()

                        if handler.detect_type(data):
                                self.handler = handler
                                return handler

                else:
                        raise DetectError


        def load(self):
                "Loads data from a file into an entrystore"

                self.check_file()
                data = file_read(self.file)

                if self.needs_password():
                        entrystore = self.handler.import_data(data, self.password)

                else:
                        entrystore = self.handler.import_data(data)

                entrystore.set_file(self.file, self.password)

                return entrystore


        def needs_password(self):
                "Checks if the current data handler requires a password"

                return self.handler.encryption


        def save(self, entrystore):
                "Saves data from an entrystore to a file"

                if self.needs_password():
                        data = self.handler.export_data(entrystore, self.password)

                else:
                        data = self.handler.export_data(entrystore)

                file_write(self.file, data)



def dir_create(dir):
        "Creates a directory, and parents if needed"

        try:
                if dir is None:
                        raise IOError

                dir = os.path.abspath(dir)

                if not file_exists(dir):
                        os.makedirs(dir)

        except OSError:
                raise IOError


def execute(command, input = None):
        "Runs a command, returns its status code and output"

        p = os.popen(command)

        if input is not None:
                p.write(input)

        output = p.read()
        status = p.close()

        return output, status


def file_exists(file):
        "Checks if a file exists"

        file = os.path.abspath(file)
        return os.access(file, os.F_OK)


def file_read(file, bytes = -1):
        "Reads data from a file"

        if file is None:
                raise IOError

        file = os.path.abspath(file)

        fp = open(file, "rb", 0)
        data = fp.read(bytes)
        fp.close()

        return data


def file_write(file, data):
        "Writes data to a file"

        if file is None:
                raise IOError

        file = os.path.abspath(file)

        # create directory if needed
        dir_create(os.path.dirname(file))

        fp = open(file, "wb", 0)
        fp.write(data)
        fp.flush()
        fp.close()