[Python-bugs-list] [ python-Bugs-699600 ] MIMEText's c'tor adds unwanted trailing newline to text

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Bugs item #699600, was opened at 2003-03-07 20:08
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=699600&group_id=5470

Category: Python Library
Group: Python 2.3
Status: Open
Resolution: None
Priority: 5
Submitted By: Trent Mick (tmick)
Assigned to: Barry A. Warsaw (bwarsaw)
Summary: MIMEText's c'tor adds unwanted trailing newline to text

Initial Comment:
I have a web form that includes a "file" type <input>. 
This means that it expects the HTTP POST data to be 
of type multipart/form-data. I was using the 'email' 
package to build this Message essentially like this:

  message = MIMEMultipart(_subtype="form-data")

  # for each non-file input
  part = MIMEText(partValue)
  message.attach(part)

  # for each file input
  content = open(filename, 'rb).read()
  part = MIMEText(content)
  message.attach()

this results in a message body (headers removed) like 
the following:

  --===============25164547096797829==
  Content-Type: text/plain; charset="us-ascii"
  MIME-Version: 1.0
  Content-Transfer-Encoding: 7bit
  Content-Disposition: form-data; name="logfile"; 
filename="D:\trentm\tmp\seuss.txt"
  
  one fish
  two fish
  three fish
  blue fish
  
  --===============25164547096797829==
  Content-Type: text/plain; charset="us-ascii"
  MIME-Version: 1.0
  Content-Transfer-Encoding: 7bit
  Content-Disposition: form-data; name="name"
    
  pliers

  --===============25164547096797829==--

The problem is those extra newlines after "blue fish" and 
after "pliers". My uploaded 
file "D:\trentm\tmp\seuss.txt" does not have a newline 
at the end. The result is that the file is changed (albeit 
slightly) on an HTTP upload.  If I use IE6 or Mozilla 1.3 
to file out this web form the multipart/form-data 
messages they generate do NOT include those extra 
newlines.

The newlines were added by this code in the 
MIMEText's constructor:

  if text[-1] <> '\n': 
      text += '\n' 

which has been around for a long time:

  http://cvs.sourceforge.net/cgi-
bin/viewcvs.cgi/mimelib/mimelib/mimelib/Text.py.diff?
r1=1.1&r2=1.2

No real reason was given for adding this code, and it 
seems hard to defend it because if I change the above to 
the following I do not get the extra newlines:

  message = MIMEMultipart(_subtype="form-data")

  # for each non-file input
  part = MIMEText(None)
  part.set_payload(partValue)
  message.attach(part)

  # for each file input
  content = open(filename, 'rb).read()
  part = MIMEText(None)
  part.set_payload(content)
  message.attach()

I suppose it is possible that there is a backward 
compatibility issue in changing this behaviour. You 
would be a better judge of that impact, Barry. Perhaps 
you could kill two birds with one stone and deprecate 
MIMEText in favor of a newly named one that drops the 
already deprecated _encoding argument as well.

Cheers,
Trent

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https://sourceforge.net/tracker/?func=detail&atid=105470&aid=699600&group_id=5470