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import os
import urlparse
from django.conf import settings
from django.core.exceptions import ImproperlyConfigured, SuspiciousOperation
from django.utils.encoding import force_unicode
from django.utils.text import get_valid_filename
from django.utils._os import safe_join
from django.core.files import locks, File
from django.core.files.move import file_move_safe
__all__ = ('Storage', 'FileSystemStorage', 'DefaultStorage', 'default_storage')
class Storage(object):
"""
A base storage class, providing some default behaviors that all other
storage systems can inherit or override, as necessary.
"""
# The following methods represent a public interface to private methods.
# These shouldn't be overridden by subclasses unless absolutely necessary.
def open(self, name, mode='rb', mixin=None):
"""
Retrieves the specified file from storage, using the optional mixin
class to customize what features are available on the File returned.
"""
file = self._open(name, mode)
if mixin:
# Add the mixin as a parent class of the File returned from storage.
file.__class__ = type(mixin.__name__, (mixin, file.__class__), {})
return file
def save(self, name, content):
"""
Saves new content to the file specified by name. The content should be a
proper File object, ready to be read from the beginning.
"""
# Get the proper name for the file, as it will actually be saved.
if name is None:
name = content.name
name = self.get_available_name(name)
name = self._save(name, content)
# Store filenames with forward slashes, even on Windows
return force_unicode(name.replace('\\', '/'))
# These methods are part of the public API, with default implementations.
def get_valid_name(self, name):
"""
Returns a filename, based on the provided filename, that's suitable for
use in the target storage system.
"""
return get_valid_filename(name)
def get_available_name(self, name):
"""
Returns a filename that's free on the target storage system, and
available for new content to be written to.
"""
# If the filename already exists, keep adding an underscore to the name
# of the file until the filename doesn't exist.
while self.exists(name):
try:
dot_index = name.rindex('.')
except ValueError: # filename has no dot
name += '_'
else:
name = name[:dot_index] + '_' + name[dot_index:]
return name
def path(self, name):
"""
Returns a local filesystem path where the file can be retrieved using
Python's built-in open() function. Storage systems that can't be
accessed using open() should *not* implement this method.
"""
raise NotImplementedError("This backend doesn't support absolute paths.")
# The following methods form the public API for storage systems, but with
# no default implementations. Subclasses must implement *all* of these.
def delete(self, name):
"""
Deletes the specified file from the storage system.
"""
raise NotImplementedError()
def exists(self, name):
"""
Returns True if a file referened by the given name already exists in the
storage system, or False if the name is available for a new file.
"""
raise NotImplementedError()
def listdir(self, path):
"""
Lists the contents of the specified path, returning a 2-tuple of lists;
the first item being directories, the second item being files.
"""
raise NotImplementedError()
def size(self, name):
"""
Returns the total size, in bytes, of the file specified by name.
"""
raise NotImplementedError()
def url(self, name):
"""
Returns an absolute URL where the file's contents can be accessed
directly by a web browser.
"""
raise NotImplementedError()
class FileSystemStorage(Storage):
"""
Standard filesystem storage
"""
def __init__(self, location=settings.MEDIA_ROOT, base_url=settings.MEDIA_URL):
self.location = os.path.abspath(location)
self.base_url = base_url
def _open(self, name, mode='rb'):
return File(open(self.path(name), mode))
def _save(self, name, content):
full_path = self.path(name)
directory = os.path.dirname(full_path)
if not os.path.exists(directory):
os.makedirs(directory)
elif not os.path.isdir(directory):
raise IOError("%s exists and is not a directory." % directory)
# There's a potential race condition between get_available_name and
# saving the file; it's possible that two threads might return the
# same name, at which point all sorts of fun happens. So we need to
# try to create the file, but if it already exists we have to go back
# to get_available_name() and try again.
while True:
try:
# This file has a file path that we can move.
if hasattr(content, 'temporary_file_path'):
file_move_safe(content.temporary_file_path(), full_path)
content.close()
# This is a normal uploadedfile that we can stream.
else:
# This fun binary flag incantation makes os.open throw an
# OSError if the file already exists before we open it.
fd = os.open(full_path, os.O_WRONLY | os.O_CREAT | os.O_EXCL | getattr(os, 'O_BINARY', 0))
try:
locks.lock(fd, locks.LOCK_EX)
for chunk in content.chunks():
os.write(fd, chunk)
finally:
locks.unlock(fd)
os.close(fd)
except OSError:
# Ooops, we need a new file name.
name = self.get_available_name(name)
full_path = self.path(name)
else:
# OK, the file save worked. Break out of the loop.
break
return name
def delete(self, name):
name = self.path(name)
# If the file exists, delete it from the filesystem.
if os.path.exists(name):
os.remove(name)
def exists(self, name):
return os.path.exists(self.path(name))
def listdir(self, path):
path = self.path(path)
directories, files = [], []
for entry in os.listdir(path):
if os.path.isdir(os.path.join(path, entry)):
directories.append(entry)
else:
files.append(entry)
return directories, files
def path(self, name):
try:
path = safe_join(self.location, name)
except ValueError:
raise SuspiciousOperation("Attempted access to '%s' denied." % name)
return os.path.normpath(path)
def size(self, name):
return os.path.getsize(self.path(name))
def url(self, name):
if self.base_url is None:
raise ValueError("This file is not accessible via a URL.")
return urlparse.urljoin(self.base_url, name).replace('\\', '/')
def get_storage_class(import_path):
try:
dot = import_path.rindex('.')
except ValueError:
raise ImproperlyConfigured("%s isn't a storage module." % import_path)
module, classname = import_path[:dot], import_path[dot+1:]
try:
mod = __import__(module, {}, {}, [''])
except ImportError, e:
raise ImproperlyConfigured('Error importing storage module %s: "%s"' % (module, e))
try:
return getattr(mod, classname)
except AttributeError:
raise ImproperlyConfigured('Storage module "%s" does not define a "%s" class.' % (module, classname))
DefaultStorage = get_storage_class(settings.DEFAULT_FILE_STORAGE)
default_storage = DefaultStorage()
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