import os import errno import urlparse import itertools from django.conf import settings from django.core.exceptions import ImproperlyConfigured, SuspiciousOperation from django.core.files import locks, File from django.core.files.move import file_move_safe from django.utils.encoding import force_unicode, filepath_to_uri from django.utils.functional import LazyObject from django.utils.importlib import import_module from django.utils.text import get_valid_filename from django.utils._os import safe_join __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. """ 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 number (before # the file extension, if one exists) to the filename until the generated # filename doesn't exist. count = itertools.count(1) while self.exists(name): # file_ext includes the dot. name = os.path.join(dir_name, "%s_%s%s" % (file_root, count.next(), file_ext)) 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=None, base_url=None): if location is None: location = settings.MEDIA_ROOT if base_url is None: 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, 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): 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, filepath_to_uri(name)) def get_storage_class(import_path=None): if import_path is None: import_path = settings.DEFAULT_FILE_STORAGE 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(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)) class DefaultStorage(LazyObject): def _setup(self): self._wrapped = get_storage_class()() default_storage = DefaultStorage()