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import os
import errno
import logging
import gobject
from olpc.datastore import layoutmanager
class FileStore(object):
def __init__(self):
self._enqueue_checksum_id = None
# 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):
dir_path = layoutmanager.get_instance().get_entry_path(uid)
if not os.path.exists(dir_path):
os.makedirs(dir_path)
destination_path = os.path.join(dir_path, uid)
if os.path.exists(file_path):
if transfer_ownership:
try:
os.rename(file_path, destination_path)
self._enqueue_checksum(uid)
completion_cb()
except OSError, e:
if e.errno == errno.EXDEV:
self._async_copy(uid, file_path, destination_path,
completion_cb)
else:
raise
else:
self._async_copy(uid, file_path, destination_path,
completion_cb)
elif file_path == '' and os.path.exists(destination_path):
os.remove(destination_path)
completion_cb()
else:
completion_cb()
def _async_copy(self, uid, file_path, destination_path, completion_cb):
async_copy = AsyncCopy(file_path, destination_path,
lambda: self._async_copy_completion_cb(uid, completion_cb))
async_copy.start()
def _async_copy_completion_cb(self, uid, completion_cb):
self._enqueue_checksum(uid)
completion_cb()
def _enqueue_checksum(self, uid):
queue_path = layoutmanager.get_instance().get_queue_path()
open(os.path.join(queue_path, uid), 'w').close()
logging.debug('_enqueue_checksum %r' % os.path.join(queue_path, uid))
if self._enqueue_checksum_id is None:
self._enqueue_checksum_id = \
gobject.idle_add(self._compute_checksum_cb)
def _identical_file_already_exists(self, checksum):
checksums_dir = layoutmanager.get_instance().get_checksums_dir()
checksum_path = os.path.join(checksums_dir, checksum)
return os.path.exists(checksum_path)
def _get_file_from_checksum(self, checksum):
checksums_dir = layoutmanager.get_instance().get_checksums_dir()
checksum_path = os.path.join(checksums_dir, checksum)
first_file_link = os.listdir(checksum_path)[0]
first_file = os.readlink(os.path.join(checksum_path, first_file_link))
return first_file
def _create_checksum_dir(self, checksum):
checksums_dir = layoutmanager.get_instance().get_checksums_dir()
checksum_path = os.path.join(checksums_dir, checksum)
logging.debug('create dir %r' % checksum_path)
os.mkdir(checksum_path)
def _add_checksum_entry(self, uid, checksum):
entry_path = layoutmanager.get_instance().get_entry_path(uid)
checksums_dir = layoutmanager.get_instance().get_checksums_dir()
checksum_path = os.path.join(checksums_dir, checksum)
logging.debug('symlink %r -> %r' % (os.path.join(entry_path, uid),
os.path.join(checksum_path, uid)))
os.symlink(os.path.join(entry_path, uid),
os.path.join(checksum_path, uid))
logging.debug('symlink %r -> %r' % \
(checksum_path, os.path.join(entry_path, 'checksum')))
os.symlink(checksum_path, os.path.join(entry_path, 'checksum'))
def _remove_checksum_entry(self, uid):
entry_path = layoutmanager.get_instance().get_entry_path(uid)
checksum = os.readlink(os.path.join(entry_path, 'checksum'))
checksums_dir = layoutmanager.get_instance().get_checksums_dir()
checksum_path = os.path.join(checksums_dir, checksum)
os.remove(os.path.join(checksum_path, uid))
try:
os.rmdir(checksum_path)
except OSError, e:
if e.errno != errno.ENOTEMPTY:
raise
os.remove(os.path.join(entry_path, 'checksum'))
def _already_linked(self, uid, checksum):
checksums_dir = layoutmanager.get_instance().get_checksums_dir()
checksum_path = os.path.join(checksums_dir, checksum)
return os.path.exists(os.path.join(checksum_path, uid))
def _compute_checksum_cb(self):
queue_path = layoutmanager.get_instance().get_queue_path()
queue = os.listdir(queue_path)
if queue:
uid = queue[0]
logging.debug('_compute_checksum_cb processing %r' % uid)
entry_path = layoutmanager.get_instance().get_entry_path(uid)
file_in_entry_path = os.path.join(entry_path, uid)
checksum = self._calculate_md5sum(os.path.join(entry_path, uid))
if self._identical_file_already_exists(checksum):
if not self._already_linked(uid, checksum):
logging.debug('delete %r' % file_in_entry_path)
os.remove(file_in_entry_path)
existing_file = self._get_file_from_checksum(checksum)
logging.debug('link %r -> %r' % \
(existing_file, file_in_entry_path))
os.link(existing_file, file_in_entry_path)
self._add_checksum_entry(uid, checksum)
else:
self._create_checksum_dir(checksum)
self._add_checksum_entry(uid, checksum)
os.remove(os.path.join(queue_path, uid))
if len(queue) <= 1:
self._enqueue_checksum_id = None
return False
else:
return True
def _calculate_md5sum(self, path):
in_, out = os.popen2(['md5sum', path])
return out.read().split(' ', 1)[0]
def retrieve(self, uid, user_id):
dir_path = layoutmanager.get_instance().get_entry_path(uid)
file_path = os.path.join(dir_path, uid)
if not os.path.exists(file_path):
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("Couldn't 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)
destination_path = os.path.join(destination_dir, uid)
# Try to make the original file readable. This can fail if the file is
# in FAT filesystem.
try:
os.chmod(file_path, 0604)
except OSError, e:
if e.errno != errno.EPERM:
raise
# 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
return destination_path
def delete(self, uid):
dir_path = layoutmanager.get_instance().get_entry_path(uid)
file_path = os.path.join(dir_path, uid)
if os.path.exists(file_path):
self._remove_checksum_entry(uid)
os.remove(file_path)
class AsyncCopy:
CHUNK_SIZE = 65536
def __init__(self, src, dest, completion):
self.src = src
self.dest = dest
self.completion = completion
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._cleanup()
self.completion(RuntimeError(
'Error writing data to destination file'))
return False
# FIXME: emit progress here
# done?
if len(data) < AsyncCopy.CHUNK_SIZE:
self._cleanup()
self.completion(None)
return False
except Exception, err:
logging.error("AC: Error copying %s -> %s: %r" % \
(self.src, self.dest, err))
self._cleanup()
self.completion(err)
return False
return True
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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