old_contents: import mimetypes
  
  import magic  # pylint: disable=E0401
  
  from django.core.exceptions import ValidationError
  from django.utils.translation import ugettext
  from django.template.defaultfilters import filesizeformat
  
  
  class RestrictedFileValidator:
  
      def __init__(self, max_upload_size):
          self.max_upload_size = max_upload_size
  
      def __call__(self, data):
          if data.size > self.max_upload_size:
              raise ValidationError(
                  ugettext('Please keep filesize under {max}. Current filesize {current}').format(
                      max=filesizeformat(self.max_upload_size),
                      current=filesizeformat(data.size)
                  )
              )
          else:
              return data
  
  
  class AllowedContentTypesByFilenameFileValidator:
  
      def __init__(self, content_types):
          self.content_types = content_types
  
      def __call__(self, data):
          extension_mime_type = mimetypes.guess_type(data.name)[0]
  
          if extension_mime_type not in self.content_types:
              raise ValidationError(ugettext('Extension of file name is not allowed'))
  
          return data
  
  
  class AllowedContentTypesByContentFileValidator:
  
      def __init__(self, content_types):
          self.content_types = content_types
  
      def __call__(self, data):
          data.open()
          with magic.Magic(flags=magic.MAGIC_MIME_TYPE) as m:
              mime_type = m.id_buffer(data.read(1024))
              data.seek(0)
              if mime_type not in self.content_types:
                  raise ValidationError(ugettext('File content was evaluated as not supported file type'))
  
          return data
  
new_contents: import mimetypes
  
  import magic  # pylint: disable=E0401
  
  from django.core.exceptions import ValidationError
  from django.utils.translation import ugettext
  from django.template.defaultfilters import filesizeformat
  
  
  class RestrictedFileValidator:
  
      def __init__(self, max_upload_size):
          self.max_upload_size = max_upload_size
  
      def __call__(self, data):
          if data.size > self.max_upload_size:
              raise ValidationError(
                  ugettext('Please keep filesize under {max}. Current filesize {current}').format(
                      max=filesizeformat(self.max_upload_size),
                      current=filesizeformat(data.size)
                  )
              )
          else:
              return data
  
  
  class AllowedContentTypesByFilenameFileValidator:
  
      def __init__(self, content_types):
          self.content_types = content_types
  
      def __call__(self, data):
          extension_mime_type = mimetypes.guess_type(data.name)[0]
  
          if extension_mime_type not in self.content_types:
              raise ValidationError(ugettext('Extension of file name is not allowed'))
  
          return data
  
  
  class AllowedContentTypesByContentFileValidator:
  
      def __init__(self, content_types):
          self.content_types = content_types
  
      def __call__(self, data):
          data.open()
          with magic.Magic(flags=magic.MAGIC_MIME_TYPE) as m:
              mime_type = m.id_buffer(data.read(2048))
              data.seek(0)
              if mime_type not in self.content_types:
                  raise ValidationError(ugettext('File content was evaluated as not supported file type'))
  
          return data
  
subject: Extend length of file read in mime validator