import os
from datetime import datetime
from urllib.parse import urljoin
from django.conf import settings
from django.core.exceptions import SuspiciousFileOperation
from django.core.files import File, locks
from django.core.files.move import file_move_safe
from django.core.signals import setting_changed
from django.utils import timezone
from django.utils._os import safe_join
from django.utils.crypto import get_random_string
from django.utils.deconstruct import deconstructible
from django.utils.encoding import filepath_to_uri
from django.utils.functional import LazyObject, cached_property
from django.utils.module_loading import import_string
from django.utils.text import get_valid_filename
__all__ = (
'Storage', 'FileSystemStorage', 'DefaultStorage', 'default_storage',
'get_storage_class',
)
[文档]class Storage:
"""
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.
[文档] def open(self, name, mode='rb'):
"""Retrieve the specified file from storage."""
return self._open(name, mode)
[文档] def save(self, name, content, max_length=None):
"""
Save 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)
name = self.get_available_name(name, max_length=max_length)
return self._save(name, content)
# These methods are part of the public API, with default implementations.
[文档] def get_valid_name(self, name):
"""
Return a filename, based on the provided filename, that's suitable for
use in the target storage system.
"""
return get_valid_filename(name)
[文档] def get_available_name(self, name, max_length=None):
"""
Return 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.
# Truncate original name if required, so the new filename does not
# exceed the max_length.
while self.exists(name) or (max_length and len(name) > max_length):
# file_ext includes the dot.
name = os.path.join(dir_name, "%s_%s%s" % (file_root, get_random_string(7), file_ext))
if max_length is None:
continue
# Truncate file_root if max_length exceeded.
truncation = len(name) - max_length
if truncation > 0:
file_root = file_root[:-truncation]
# Entire file_root was truncated in attempt to find an available filename.
if not file_root:
raise SuspiciousFileOperation(
'Storage can not find an available filename for "%s". '
'Please make sure that the corresponding file field '
'allows sufficient "max_length".' % name
)
name = os.path.join(dir_name, "%s_%s%s" % (file_root, get_random_string(7), file_ext))
return name
[文档] def generate_filename(self, filename):
"""
Validate the filename by calling get_valid_name() and return a filename
to be passed to the save() method.
"""
# `filename` may include a path as returned by FileField.upload_to.
dirname, filename = os.path.split(filename)
return os.path.normpath(os.path.join(dirname, self.get_valid_name(filename)))
[文档] def path(self, name):
"""
Return 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.
[文档] def delete(self, name):
"""
Delete the specified file from the storage system.
"""
raise NotImplementedError('subclasses of Storage must provide a delete() method')
[文档] def exists(self, name):
"""
Return True if a file referenced by the given name already exists in the
storage system, or False if the name is available for a new file.
"""
raise NotImplementedError('subclasses of Storage must provide an exists() method')
[文档] def listdir(self, path):
"""
List the contents of the specified path. Return a 2-tuple of lists:
the first item being directories, the second item being files.
"""
raise NotImplementedError('subclasses of Storage must provide a listdir() method')
[文档] def size(self, name):
"""
Return the total size, in bytes, of the file specified by name.
"""
raise NotImplementedError('subclasses of Storage must provide a size() method')
[文档] def url(self, name):
"""
Return an absolute URL where the file's contents can be accessed
directly by a Web browser.
"""
raise NotImplementedError('subclasses of Storage must provide a url() method')
[文档] def get_accessed_time(self, name):
"""
Return the last accessed time (as a datetime) of the file specified by
name. The datetime will be timezone-aware if USE_TZ=True.
"""
raise NotImplementedError('subclasses of Storage must provide a get_accessed_time() method')
[文档] def get_created_time(self, name):
"""
Return the creation time (as a datetime) of the file specified by name.
The datetime will be timezone-aware if USE_TZ=True.
"""
raise NotImplementedError('subclasses of Storage must provide a get_created_time() method')
[文档] def get_modified_time(self, name):
"""
Return the last modified time (as a datetime) of the file specified by
name. The datetime will be timezone-aware if USE_TZ=True.
"""
raise NotImplementedError('subclasses of Storage must provide a get_modified_time() method')
[文档]@deconstructible
class FileSystemStorage(Storage):
"""
Standard filesystem storage
"""
# The combination of O_CREAT and O_EXCL makes os.open() raise OSError if
# the file already exists before it's opened.
OS_OPEN_FLAGS = os.O_WRONLY | os.O_CREAT | os.O_EXCL | getattr(os, 'O_BINARY', 0)
def __init__(self, location=None, base_url=None, file_permissions_mode=None,
directory_permissions_mode=None):
self._location = location
self._base_url = base_url
self._file_permissions_mode = file_permissions_mode
self._directory_permissions_mode = directory_permissions_mode
setting_changed.connect(self._clear_cached_properties)
def _clear_cached_properties(self, setting, **kwargs):
"""Reset setting based property values."""
if setting == 'MEDIA_ROOT':
self.__dict__.pop('base_location', None)
self.__dict__.pop('location', None)
elif setting == 'MEDIA_URL':
self.__dict__.pop('base_url', None)
elif setting == 'FILE_UPLOAD_PERMISSIONS':
self.__dict__.pop('file_permissions_mode', None)
elif setting == 'FILE_UPLOAD_DIRECTORY_PERMISSIONS':
self.__dict__.pop('directory_permissions_mode', None)
def _value_or_setting(self, value, setting):
return setting if value is None else value
@cached_property
def base_location(self):
return self._value_or_setting(self._location, settings.MEDIA_ROOT)
@cached_property
def location(self):
return os.path.abspath(self.base_location)
@cached_property
def base_url(self):
if self._base_url is not None and not self._base_url.endswith('/'):
self._base_url += '/'
return self._value_or_setting(self._base_url, settings.MEDIA_URL)
@cached_property
def file_permissions_mode(self):
return self._value_or_setting(self._file_permissions_mode, settings.FILE_UPLOAD_PERMISSIONS)
@cached_property
def directory_permissions_mode(self):
return self._value_or_setting(self._directory_permissions_mode, settings.FILE_UPLOAD_DIRECTORY_PERMISSIONS)
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.
directory = os.path.dirname(full_path)
if not os.path.exists(directory):
try:
if self.directory_permissions_mode is not None:
# Set the umask because os.makedirs() doesn't apply the "mode"
# argument to intermediate-level directories.
old_umask = os.umask(0o777 & ~self.directory_permissions_mode)
try:
os.makedirs(directory, self.directory_permissions_mode)
finally:
os.umask(old_umask)
else:
os.makedirs(directory)
except FileExistsError:
# There's a race between os.path.exists() and os.makedirs().
# If os.makedirs() fails with FileExistsError, the directory
# was created concurrently.
pass
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)
# This is a normal uploadedfile that we can stream.
else:
# The current umask value is masked out by os.open!
fd = os.open(full_path, self.OS_OPEN_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 FileExistsError:
# A new name is needed if the file exists.
name = self.get_available_name(name)
full_path = self.path(name)
else:
# OK, the file save worked. Break out of the loop.
break
if self.file_permissions_mode is not None:
os.chmod(full_path, self.file_permissions_mode)
# Store filenames with forward slashes, even on Windows.
return name.replace('\\', '/')
def delete(self, name):
assert name, "The name argument is not allowed to be empty."
name = self.path(name)
# If the file or directory exists, delete it from the filesystem.
try:
if os.path.isdir(name):
os.rmdir(name)
else:
os.remove(name)
except FileNotFoundError:
# FileNotFoundError is raised if the file or directory was removed
# concurrently.
pass
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.scandir(path):
if entry.is_dir():
directories.append(entry.name)
else:
files.append(entry.name)
return directories, files
def path(self, name):
return safe_join(self.location, name)
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.")
url = filepath_to_uri(name)
if url is not None:
url = url.lstrip('/')
return urljoin(self.base_url, url)
def _datetime_from_timestamp(self, ts):
"""
If timezone support is enabled, make an aware datetime object in UTC;
otherwise make a naive one in the local timezone.
"""
if settings.USE_TZ:
# Safe to use .replace() because UTC doesn't have DST
return datetime.utcfromtimestamp(ts).replace(tzinfo=timezone.utc)
else:
return datetime.fromtimestamp(ts)
def get_accessed_time(self, name):
return self._datetime_from_timestamp(os.path.getatime(self.path(name)))
[文档] def get_created_time(self, name):
return self._datetime_from_timestamp(os.path.getctime(self.path(name)))
def get_modified_time(self, name):
return self._datetime_from_timestamp(os.path.getmtime(self.path(name)))
[文档]def get_storage_class(import_path=None):
return import_string(import_path or settings.DEFAULT_FILE_STORAGE)
[文档]class DefaultStorage(LazyObject):
def _setup(self):
self._wrapped = get_storage_class()()
default_storage = DefaultStorage()
