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# Copyright (C) 2008, One Laptop Per Child
#
# 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 St, Fifth Floor, Boston, MA 02110-1301 USA
import os
import errno
import logging
import tempfile
import gobject
from carquinyol import layoutmanager
class FileStore(object):
"""Handle the storage of one file per entry.
"""
# TODO: add protection against store and retrieve operations on entries
# that are being processed async.
def store(self, uid, file_path, transfer_ownership, completion_cb):
"""Store a file for a given entry.
"""
dir_path = layoutmanager.get_instance().get_entry_path(uid)
if not os.path.exists(dir_path):
os.makedirs(dir_path)
destination_path = layoutmanager.get_instance().get_data_path(uid)
if file_path:
if not os.path.isfile(file_path):
raise ValueError('No file at %r' % file_path)
if transfer_ownership:
try:
logging.debug('FileStore moving from %r to %r', file_path,
destination_path)
os.rename(file_path, destination_path)
completion_cb()
except OSError, e:
if e.errno == errno.EXDEV:
self._async_copy(file_path, destination_path,
completion_cb, unlink_src=True)
else:
raise
else:
self._async_copy(file_path, destination_path, completion_cb,
unlink_src=False)
"""
TODO: How can we support deleting the file of an entry?
elif not file_path and os.path.exists(destination_path):
logging.debug('FileStore: deleting %r' % destination_path)
os.remove(destination_path)
completion_cb()
"""
else:
logging.debug('FileStore: Nothing to do')
completion_cb()
def _async_copy(self, file_path, destination_path, completion_cb,
unlink_src):
"""Start copying a file asynchronously.
"""
logging.debug('FileStore copying from %r to %r', file_path,
destination_path)
async_copy = AsyncCopy(file_path, destination_path, completion_cb,
unlink_src)
async_copy.start()
def retrieve(self, uid, user_id, extension):
"""Place the file associated to a given entry into a directory
where the user can read it. The caller is reponsible for
deleting this file.
"""
file_path = layoutmanager.get_instance().get_data_path(uid)
if not os.path.exists(file_path):
logging.debug('Entry %r doesnt have any file', uid)
return ''
use_instance_dir = os.path.exists('/etc/olpc-security') and \
os.getuid() != user_id
if use_instance_dir:
if not user_id:
raise ValueError('Couldnt determine the current user uid.')
destination_dir = os.path.join(os.environ['HOME'], 'isolation',
'1', 'uid_to_instance_dir', str(user_id))
else:
profile = os.environ.get('SUGAR_PROFILE', 'default')
destination_dir = os.path.join(os.path.expanduser('~'), '.sugar',
profile, 'data')
if not os.path.exists(destination_dir):
os.makedirs(destination_dir)
if extension is None:
extension = ''
elif extension:
extension = '.' + extension
destination_path = os.path.join(destination_dir, uid + extension)
attempt = 1
while os.path.exists(destination_path):
if attempt > 10:
fd_, destination_path = tempfile.mkstemp(prefix=uid,
suffix=extension,
dir=destination_dir)
del fd_
os.unlink(destination_path)
break
else:
file_name = '%s_%s%s' % (uid, attempt, extension)
destination_path = os.path.join(destination_dir, file_name)
attempt += 1
# Try to hard link from the original file to the targetpath. This can
# fail if the file is in a different filesystem. Do a symlink instead.
try:
os.link(file_path, destination_path)
except OSError, e:
if e.errno == errno.EXDEV:
os.symlink(file_path, destination_path)
else:
raise
# Try to make the original file readable. This can fail if the file is
# in a FAT filesystem.
try:
os.chmod(file_path, 0604)
except OSError, e:
if e.errno != errno.EPERM:
raise
return destination_path
def get_file_path(self, uid):
return layoutmanager.get_instance().get_data_path(uid)
def delete(self, uid):
"""Remove the file associated to a given entry.
"""
file_path = layoutmanager.get_instance().get_data_path(uid)
if os.path.exists(file_path):
os.remove(file_path)
def hard_link_entry(self, new_uid, existing_uid):
existing_file = layoutmanager.get_instance().get_data_path(existing_uid)
new_file = layoutmanager.get_instance().get_data_path(new_uid)
logging.debug('removing %r', new_file)
os.remove(new_file)
logging.debug('hard linking %r -> %r', new_file, existing_file)
os.link(existing_file, new_file)
class AsyncCopy(object):
"""Copy a file in chunks in the idle loop.
"""
CHUNK_SIZE = 65536
def __init__(self, src, dest, completion, unlink_src=False):
self.src = src
self.dest = dest
self.completion = completion
self._unlink_src = unlink_src
self.src_fp = -1
self.dest_fp = -1
self.written = 0
self.size = 0
def _cleanup(self):
os.close(self.src_fp)
os.close(self.dest_fp)
def _copy_block(self, user_data=None):
try:
data = os.read(self.src_fp, AsyncCopy.CHUNK_SIZE)
count = os.write(self.dest_fp, data)
self.written += len(data)
# error writing data to file?
if count < len(data):
logging.error('AC: Error writing %s -> %s: wrote less than '
'expected', self.src, self.dest)
self._complete(RuntimeError(
'Error writing data to destination file'))
return False
# FIXME: emit progress here
# done?
if len(data) < AsyncCopy.CHUNK_SIZE:
self._complete(None)
return False
except Exception, err:
logging.error('AC: Error copying %s -> %s: %r', self.src, self.
dest, err)
self._complete(err)
return False
return True
def _complete(self, *args):
self._cleanup()
if self._unlink_src:
os.unlink(self.src)
self.completion(*args)
def start(self):
self.src_fp = os.open(self.src, os.O_RDONLY)
self.dest_fp = os.open(self.dest, os.O_RDWR | os.O_TRUNC | os.O_CREAT,
0644)
stat = os.fstat(self.src_fp)
self.size = stat[6]
gobject.idle_add(self._copy_block)
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