[Bug 1170966] [NEW] HyperArch.py throws IndexError: string index out of range

[Mark Sapiro]

Public bug reported:

There is code in Mailman/Archiver/HyperArch.py which gets the character
set of a message in order to convert it if necessary to the character
set of the archive. The code is

        charset = message.get_content_charset(cset_out)
        if charset:
            charset = charset.lower().strip()
            if charset[0]=='"' and charset[-1]=='"':
                charset = charset[1:-1]
            if charset[0]=="'" and charset[-1]=="'":
                charset = charset[1:-1]

This code can throw an IndexError if get_content_charset() returns a
non-null string containing only white space, e.g. a single new-line. It
has been reported that this occurs resulting in tracebacks which end
with something like

  File "Mailman/Archiver/HyperArch.py", line 311, in __init__
    if charset[0]=='"' and charset[-1]=='"':
IndexError: string index out of range

The obvious, 'simple' fix for this is to change

        if charset:

to

        if charset and charset.strip():

which will avoid the exception, but I really want to see an actual
message that triggers this error as a test case for this and future
changes.

Unfortunately, despite trying with multiple versions of the Python email
package, the only way I can get get_content_charset() to return a
whitespace only result is with a header like

Content-Type: text/plain; charset=" "

which seems a bit too contrived to actually occur in the wild.

Thus, if anyone can provide an actual message that triggers this
exception, please attach it here.

** Affects: mailman
     Importance: Undecided
     Assignee: Mark Sapiro (msapiro)
         Status: Incomplete

** Changed in: mailman
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1170966

Title:
  HyperArch.py throws IndexError: string index out of range

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