pithcat 4.02 KB
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#!/usr/bin/env python

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# Copyright (C) 2011 GRNET S.A.
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#
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# 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.
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#
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# 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.
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#
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# 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.
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"""
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
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from sys import exit, stdout, stderr
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from os import environ
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from binascii import hexlify, unhexlify
from collections import namedtuple
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try:
    from pithos.backends.modular import ModularBackend
except ImportError:
    stderr.write("Pithos backend was not found.\n")
    exit(2)
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parser = OptionParser(usage='%prog [options] <URL>')
parser.add_option('--db', dest='db', metavar='URI',
        help='SQLAlchemy URI of the database [REQUIRED]')
parser.add_option('--data', dest='data', metavar='DIR',
        help='path to the directory where data are stored [REQUIRED]')
parser.add_option('-s', action='store_true', dest='size', default=False,
        help='print file size and exit')

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LocationURL = namedtuple('LocationURL', ['account', 'container', 'object'])
HashmapURL = namedtuple('HashmapURL', ['hash', 'size'])
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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")
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def print_size(backend, url):
    """Writes object's size to stdout."""
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    url = parse_url(url)
    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")
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def print_data(backend, url):
    """Writes object's size to stdout."""
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    url = parse_url(url)
    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")

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    for hash in hashmap:
        block = backend.get_block(hash)
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        if len(block) > size:
            block = block[:size]
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        stdout.write(block)
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        size -= len(block)
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def main():
    options, args = parser.parse_args()
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    if len(args) != 1:
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        parser.print_help()
        exit(1)

    url = args[0]
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    if not options.data and 'PITHCAT_INPUT_DATA' not in environ:
        stderr.write("Pithos data directory path is missing.\n")
        exit(1)

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

    if not options.db and 'PITHCAT_INPUT_DB' not in environ:
        stderr.write("Pithos database uri is missing.\n")
        exit(1)

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

    backend = ModularBackend(None, db_uri, None, data_path)

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    if options.size:
        print_size(backend, url)
    else:
        print_data(backend, url)

if __name__ == '__main__':
    main()