import os
import errno
from datetime import datetime
from django.conf import settings
from django.core.exceptions import SuspiciousFileOperation
from django.core.files import locks, File
from django.core.files.move import file_move_safe
from django.utils.crypto import get_random_string
from django.utils.encoding import force_text, filepath_to_uri
from django.utils.functional import LazyObject
from django.utils.module_loading import import_by_path
from django.utils.six.moves.urllib.parse import urljoin
from django.utils.text import get_valid_filename
from django.utils._os import safe_join, abspathu
__all__ = ('Storage', 'FileSystemStorage', 'DefaultStorage', 'default_storage')
[docs]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.
[docs] def open(self, name, mode='rb'):
"""
Retrieves the specified file from storage.
"""
return self._open(name, mode)
[docs] def save(self, name, content):
"""
Saves new content to the file specified by name. The content should be
a proper File object or any python file-like 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
if not hasattr(content, 'chunks'):
content = File(content)
name = self.get_available_name(name)
name = self._save(name, content)
# Store filenames with forward slashes, even on Windows
return force_text(name.replace('\\', '/'))
# These methods are part of the public API, with default implementations.
[docs] 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)
[docs] 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.
"""
dir_name, file_name = os.path.split(name)
file_root, file_ext = os.path.splitext(file_name)
# If the filename already exists, add an underscore and a random 7
# character alphanumeric string (before the file extension, if one
# exists) to the filename until the generated filename doesn't exist.
while self.exists(name):
# file_ext includes the dot.
name = os.path.join(dir_name, "%s_%s%s" % (file_root, get_random_string(7), file_ext))
return name
[docs] 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.
[docs] def delete(self, name):
"""
Deletes the specified file from the storage system.
"""
raise NotImplementedError()
[docs] 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()
[docs] 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()
[docs] def size(self, name):
"""
Returns the total size, in bytes, of the file specified by name.
"""
raise NotImplementedError()
[docs] def url(self, name):
"""
Returns an absolute URL where the file's contents can be accessed
directly by a Web browser.
"""
raise NotImplementedError()
[docs] def accessed_time(self, name):
"""
Returns the last accessed time (as datetime object) of the file
specified by name.
"""
raise NotImplementedError()
[docs] def created_time(self, name):
"""
Returns the creation time (as datetime object) of the file
specified by name.
"""
raise NotImplementedError()
[docs] def modified_time(self, name):
"""
Returns the last modified time (as datetime object) of the file
specified by name.
"""
raise NotImplementedError()
[docs]class FileSystemStorage(Storage):
"""
Standard filesystem storage
"""
def __init__(self, location=None, base_url=None):
if location is None:
location = settings.MEDIA_ROOT
self.base_location = location
self.location = abspathu(self.base_location)
if base_url is None:
base_url = settings.MEDIA_URL
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)
# Create any intermediate directories that do not exist.
# Note that there is a race between os.path.exists and os.makedirs:
# if os.makedirs fails with EEXIST, the directory was created
# concurrently, and we can continue normally. Refs #16082.
directory = os.path.dirname(full_path)
if not os.path.exists(directory):
try:
os.makedirs(directory)
except OSError as e:
if e.errno != errno.EEXIST:
raise
if 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.
flags = (os.O_WRONLY | os.O_CREAT | os.O_EXCL |
getattr(os, 'O_BINARY', 0))
# The current umask value is masked out by os.open!
fd = os.open(full_path, flags, 0o666)
_file = None
try:
locks.lock(fd, locks.LOCK_EX)
for chunk in content.chunks():
if _file is None:
mode = 'wb' if isinstance(chunk, bytes) else 'wt'
_file = os.fdopen(fd, mode)
_file.write(chunk)
finally:
locks.unlock(fd)
if _file is not None:
_file.close()
else:
os.close(fd)
except OSError as e:
if e.errno == errno.EEXIST:
# Ooops, the file exists. We need a new file name.
name = self.get_available_name(name)
full_path = self.path(name)
else:
raise
else:
# OK, the file save worked. Break out of the loop.
break
if settings.FILE_UPLOAD_PERMISSIONS is not None:
os.chmod(full_path, settings.FILE_UPLOAD_PERMISSIONS)
return name
def delete(self, name):
assert name, "The name argument is not allowed to be empty."
name = self.path(name)
# If the file exists, delete it from the filesystem.
# Note that there is a race between os.path.exists and os.remove:
# if os.remove fails with ENOENT, the file was removed
# concurrently, and we can continue normally.
if os.path.exists(name):
try:
os.remove(name)
except OSError as e:
if e.errno != errno.ENOENT:
raise
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 SuspiciousFileOperation("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 urljoin(self.base_url, filepath_to_uri(name))
def accessed_time(self, name):
return datetime.fromtimestamp(os.path.getatime(self.path(name)))
def created_time(self, name):
return datetime.fromtimestamp(os.path.getctime(self.path(name)))
def modified_time(self, name):
return datetime.fromtimestamp(os.path.getmtime(self.path(name)))
[docs]def get_storage_class(import_path=None):
return import_by_path(import_path or settings.DEFAULT_FILE_STORAGE)
default_storage = DefaultStorage()
Oct 03, 2017