使用sorl-thumbnail时的可疑操作

Question

我有一个Django的网页应用，它可以代表用户访问和操作几个服务器上的文件系统（比如说/fs01、/fs02等等）。我想把这些文件系统里的图片做成缩略图展示给用户，所以我觉得可以用sorl-thumbnail来实现。

不过，看起来sorl-thumbnail要生成缩略图，图片必须放在MEDIA_ROOT目录下。我的MEDIA_ROOT设置为/Users/me/Dev/MyProject/myproj/media，这样是可以正常工作的：

path = "/Users/me/Dev/MyProject/myproj/media/pipe-img/magritte-pipe-large.jpg"
try:
  im = get_thumbnail(path, '100x100', crop='center', quality=99)
except Exception, e:
  exc_type, exc_obj, exc_tb = sys.exc_info()
  print "Failed getting thumbnail: (%s) %s" % (exc_type, e)
print "im.url = %s" % im.url

它成功生成了缩略图，并且打印出了im.url，这正是我期待的结果。但是当我把path改成：

path = "/fs02/dir/ep340102/foo/2048x1024/magritte-pipe-large.jpg"

就出现了错误：

Failed getting thumbnail: (<class 'django.core.exceptions.SuspiciousOperation'>)
Attempted access to '/fs02/dir/ep340102/foo/2048x1024/magritte-pipe-large.jpg' denied.

有没有办法解决这个问题呢？我能不能用sorl-thumbnail在这些其他文件系统下（比如/fs01、/fs02、/fs03等等）生成缩略图？有没有更好的方法呢？

更新。 这是完整的错误信息：

Environment:


Request Method: GET
Request URL: http://localhost:8000/pipe/file_selection/

Django Version: 1.4.1
Python Version: 2.7.2
Installed Applications:
('django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.sites',
 'django.contrib.admin',
 'django.contrib.admindocs',
 'django.contrib.humanize',
 'django.contrib.messages',
 'pipeproj.pipe',
 'south',
 'guardian',
 'sorl.thumbnail')
Installed Middleware:
('django.middleware.common.CommonMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware')


Traceback:
File "/Library/Python/2.7/site-packages/django/core/handlers/base.py" in get_response
  111.                         response = callback(request, *callback_args, **callback_kwargs)
File "/Library/Python/2.7/site-packages/django/contrib/auth/decorators.py" in _wrapped_view
  20.                 return view_func(request, *args, **kwargs)
File "/Users/dylan/Dev/Pipe/pipeproj/../pipeproj/pipe/views/data.py" in file_selection
  184.  im = get_thumbnail(path, '100x100', crop='center', quality=99)
File "/Library/Python/2.7/site-packages/sorl_thumbnail-11.12-py2.7.egg/sorl/thumbnail/shortcuts.py" in get_thumbnail
  8.     return default.backend.get_thumbnail(file_, geometry_string, **options)
File "/Library/Python/2.7/site-packages/sorl_thumbnail-11.12-py2.7.egg/sorl/thumbnail/base.py" in get_thumbnail
  56.             source_image = default.engine.get_image(source)
File "/Library/Python/2.7/site-packages/sorl_thumbnail-11.12-py2.7.egg/sorl/thumbnail/engines/pil_engine.py" in get_image
  12.         buf = StringIO(source.read())
File "/Library/Python/2.7/site-packages/sorl_thumbnail-11.12-py2.7.egg/sorl/thumbnail/images.py" in read
  121.         return self.storage.open(self.name).read()
File "/Library/Python/2.7/site-packages/django/core/files/storage.py" in open
  33.         return self._open(name, mode)
File "/Library/Python/2.7/site-packages/django/core/files/storage.py" in _open
  156.         return File(open(self.path(name), mode))
File "/Library/Python/2.7/site-packages/django/core/files/storage.py" in path
  246.             raise SuspiciousOperation("Attempted access to '%s' denied." % name)

Exception Type: SuspiciousOperation at /pipe/file_selection/
Exception Value: Attempted access to '/fs02/dir/ep340102/foo/2048x1024/bettina.jpg' denied.

Answer 1

我通过提供一个绝对网址来解决这个问题，像这样：

from sorl.thumbnail import get_thumbnail
from django.contrib.staticfiles.storage import staticfiles_storage

image_url = staticfiles_storage.url('image.jpg')
thumbnail = get_thumbnail(image_url, '100x100')

Answer 2

你执行下面这个命令会得到什么结果呢？

ls -la /fs02/dir/ep340102/foo/2048x1024/

通常情况下，如果文件的拥有者不对或者文件权限设置错误，就会出现“访问被拒绝”的情况...

Answer 3

SuspiciousOperation这个问题是来自FileSystemStorage.path()，具体在这里：

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)

它的来源是safe_join()，这个函数里有一个检查：

if (not normcase(final_path).startswith(normcase(base_path + sep)) and
...

这意味着计算出来的文件名必须在你设置的缩略图存储里。默认情况下，settings.THUMBNAIL_STORAGE是settings.DEFAULT_FILE_STORAGE，而DEFAULT_FILE_STORAGE是FileSystemStorage，它会把文件存储在settings.MEDIA_ROOT里。

如果你想为缩略图使用不同的存储路径，可以通过定义一个存储类来实现：

from django.core.files.storage import FileSystemStorage

class ThumbnailStorage(FileSystemStorage):
    def __init__(self, **kwargs):
        super(ThumbnailStorage, self).__init__(
            location='/fs02', base_url='/fs02')

然后在settings.py文件里进行设置：

THUMBNAIL_STORAGE = 'myproj.storage.ThumbnailStorage'

你还需要确保在那个URL上有东西在提供/fs02的服务：

if settings.DEBUG:
    patterns += patterns('',
        url(r'^fs02/(?P<path>.*)$', 'django.views.static.serve',
            {'document_root': '/fs02'}))

注意，你的缩略图会按照默认的THUMBNAIL_PREFIX创建为/fs02/cache/...的格式。