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#!/usr/bin/env python

# Copyright (C) 2011-2013 GRNET S.A.

#

# 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., 51 Franklin Street, Fifth Floor, Boston, MA

# 02110-1301, USA.

"""

A tool that connects to the Pithos backend and returns the size and contents

of a pithos object.

Since the backend does not have a "root" account we use the account given in

the URL as the user when connecting to the backend.

"""

from optparse import OptionParser, OptionGroup

from sys import exit, stdout, stderr

from os import environ

from binascii import hexlify, unhexlify

from collections import namedtuple

try:

    from pithos.backends.modular import ModularBackend

except ImportError:

    stderr.write("Pithos backend was not found.\n")

    exit(2)

parser = OptionParser(usage='%prog [options] <URL>')

parser.add_option('--data', dest='data', metavar='DIR',

                  help='path to the directory where data are stored')

parser.add_option('-s', action='store_true', dest='size', default=False,

                  help='print file size and exit')

group = OptionGroup(

    parser, "Dangerous Options",

    "Caution: If the <URL> is a LocationURL (pithos://...), then you'll also "

    "need to define a database URI. You can use the `--db' option to do so, "

    "but this raises security concerns. For database URI's and pithos data "

    "paths, the recommended way to define them is to use the PITHCAT_INPUT_DB "

    "and PITHCAT_INPUT_DATA environmental variables respectfully.")

group.add_option('--db', dest='db', metavar='URI',

                 help='SQLAlchemy URI of the database', default=None)

parser.add_option_group(group)

LocationURL = namedtuple('LocationURL', ['account', 'container', 'object'])

HashmapURL = namedtuple('HashmapURL', ['hash', 'size'])

def parse_url(url):

    if url.startswith('pithos://'):

        t = url.split('/', 4)

        assert len(t) == 5, "Invalid URL"

        return LocationURL(*t[2:5])

    elif url.startswith('pithosmap://'):

        t = url.split('/', 3)

        assert len(t) == 4, "Invalid URL"

        return HashmapURL(*t[2:4])

    else:

        raise Exception("Invalid URL")

def print_size(backend, url):

    """Writes object's size to stdout."""

    if type(url) is LocationURL:

        account, container, object = url

        meta = backend.get_object_meta(account, account, container, object,

                                       None)

        print meta['bytes']

    elif type(url) is HashmapURL:

        print url.size

    else:

        raise Exception("Invalid URL")

def print_data(backend, url):

    """Writes object's size to stdout."""

    if type(url) is LocationURL:

        account, container, object = url

        size, hashmap = backend.get_object_hashmap(account, account, container,

                                                   object)

    elif type(url) is HashmapURL:

        hashmap = [hexlify(x)

                   for x in backend.store.map_get(unhexlify(url.hash))]

        size = int(url.size)

    else:

        raise Exception("Invalid URL")

    for hash in hashmap:

        block = backend.get_block(hash)

        if len(block) > size:

            block = block[:size]

        stdout.write(block)

        size -= len(block)

def main():

    options, args = parser.parse_args()

    if len(args) != 1:

        parser.print_help()

        exit(1)

    url = parse_url(args[0])

    if not options.data and 'PITHCAT_INPUT_DATA' not in environ:

        stderr.write(

            "Pithos data directory path is missing.\n"

            "Use the PITHCAT_INPUT_DATA environmental variable (recommended) "

            "or the --data command line option to define it.\n")

        exit(1)

    data_path = environ['PITHCAT_INPUT_DATA'] if not options.data else \

        options.data

    if options.db is None and 'PITHCAT_INPUT_DB' not in environ and \

            type(url) is LocationURL:

        stderr.write(

            "Pithos database uri is missing.\n"

            "Use the PITHCAT_INPUT_DB environmental variable (recommended) "

            "or the --db command line option to define it.\n")

        exit(1)

    db_uri = environ['PITHCAT_INPUT_DB'] if not options.db else options.db

    backend = ModularBackend(None,

                             db_uri if type(url) is LocationURL else None,

                             None,

                             data_path)

    if options.size:

        print_size(backend, url)

    else:

        print_data(backend, url)

if __name__ == '__main__':

    main()

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