A valid JPEG file is rejected due to it's file name.

[arizonagroovejet]

A valid JPEG file is rejected due to it's file name.

Steps to recreate:

$ imgFile=$(mktemp)
$ convert rose:- JPEG:- > ${imgFile}
$ file ${imgFile}
/tmp/tmp.29bSaJRIFj: JPEG image data, JFIF standard 1.01, aspect ratio, density 1x1, segment length 16, baseline, precision 8, 70x46, frames 3
$ cat tweetIt.py 
#!/usr/bin/python
import tweepy
import sys
consumer_key        = 'wgrg'
consumer_secret     = 'ergr'
access_token        = 'reg'
access_token_secret = 'oino'
auth = tweepy.OAuthHandler(consumer_key, consumer_secret)
auth.set_access_token(access_token, access_token_secret)
api = tweepy.API(auth)
media_ids=[api.media_upload(sys.argv[2]).media_id_string]
api.update_status(status=sys.argv[1],media_ids=media_ids)
$ ./tweetIt.py "foo" "${imgFile}"

Expected results:

The JPEG file /tmp/tmp.29bSaJRIFj is tweeted along with the text "foo".

Actual results:

Traceback (most recent call last):
  File "./tweetIt.py", line 18, in <module>
    media_ids=[api.media_upload(sys.argv[2]).media_id_string]
  File "/usr/lib/python2.7/site-packages/tweepy/api.py", line 201, in media_upload
    headers, post_data = API._pack_image(filename, 3072, form_field='media', f=f)
  File "/usr/lib/python2.7/site-packages/tweepy/api.py", line 1323, in _pack_image
    raise TweepError('Invalid file type for image: %s' % file_type)
tweepy.error.TweepError: Invalid file type for image: None

Additional information:

The version of Tweepy I'm using is a bit out of date

$ rpm -qf /usr/lib/python2.7/site-packages/tweepy/api.py
python2-tweepy-3.5.0-6.fc28.noarch

but I can see the issue will occur with the current version too because the behaviour results from using mimetypes.guess_type()

tweepy/tweepy/api.py

Line 1316 in 8ad187e

file_type = mimetypes.guess_type(filename)

which guesses the file type based on the file name.

It's very common on Unix-like operating systems for shell scripts to use files the name of which is generated by mktemp. That's how I encountered this issue. Some versions of mktemp support providing a suffix, e.g. $ imgFile=$(mktemp --suffix=.jpg) but some versions of mktemp do not support providing a suffix.

imghdr https://docs.python.org/2/library/imghdr.html determines the type of image contained in a file by looking at the file's contents.

Python 2.7.15 (default, May 16 2018, 17:50:09) 
[GCC 8.1.1 20180502 (Red Hat 8.1.1-1)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import imghdr
>>> imghdr.what('tmp.29bSaJRIFj')
'jpeg'