How to get bytes of image in StringIO container

Question

I am am getting an image from email attachment and will never touch disk. Image will be placed into a StringIO container and processed by PIL. How do I get the file size in bytes?

image_file = StringIO('image from email')
im = Image.open(image_file)

Answer 1

Use StringIO's .tell() method by seeking to the end of the file:

>>> from StringIO import StringIO
>>> s = StringIO("foobar")
>>> s.tell()
0
>>> s.seek(0, 2)
>>> s.tell()
6

In your case:

image_file = StringIO('image from email')
image_file.seek(0, 2)  # Seek to the end
bytes = image_file.tell()  # Get no. of bytes
image_file.seek(0)  # Seek to the start
im = Image.open(image_file)