Re: Re: installing an end user editable file

[Lars Buitinck <larsmans@gmail.com>]

2011/2/14 james frize <jamesfrize@gmail.com>:
> Hey mentors,

I'm not a mentor, I just lurk on this list to learn.


> I like the idea of having a default copy of the file used by my
> program, as suggested by Lars and PJ, so I've altered my source code
> to use a default file and allow multiple users to have their own
> copies of this file in their home/<user>/Documents folder.
>
> "creating a default file in /usr/share and having the program copy it
> to the user's directory when it's run"
>
> However, I can't open a file from /usr/share via my python script as I
> don't have permission to open files in a protected directory, and
> after reading up a bit on it, it's been suggested that it's bad form
> to invoke super user in a script, as it's construed as a security risk
> (i.e. http://tldp.org/HOWTO/Security-HOWTO/file-security.html;
> http://www.velocityreviews.com/forums/t346075-sudo-open-python-newbee-question.html)
>
> Do I really have to use sudo or super user privileges to just open and
> copy a text template?

Not at all. I was thinking along the lines of:


def homedir():
    '''Get current user's homedir'''

   home = os.getenv('HOME')
   if home == None:
      raise IOError('cannot copy links.txt: HOME not set')
   return home

def open_links_txt():
   '''Open links.txt; install for current user if necessary'''

   # http://standards.freedesktop.org/basedir-spec/basedir-spec-0.6.html
   datadir = os.getenv('XDG_DATA_HOME')
   if datadir == None:
      datadir = os.path.join(homedir(), '.local', 'share')

   links_txt = os.path.join(datadir, 'links.txt')

   if not os.path.exists(links_txt):
      shutil.copy('/usr/share/gtk-link-lizard/links.txt', links_txt)

   return open(links_txt)


Notes:
* UNTESTED CODE, may contain the stupidest of syntax errors or worse
* contains a race condition due to the use of os.path.exists, but that
shoudn't matter unless the user sets XDG_DATA_HOME to the wrong value
or has a world-writable homedir (in which case s/he's doomed anyway)
* I know this doesn't fit the original app particularly well, so
please integrate with existing code.


> Where do packagers normally install files of this type?

I put it in /usr/share/gtk-link-lizard for the purpose of the example.
I don't know the Debian packaging rules by heart, but /usr/share/doc
seems to be the wrong place; that's for documentation. It should be
safe to remove documentation (sudo rm -rf /usr/share/doc) without
applications suddenly starting to malfunction.


> I thought it might be a good idea to store it in
> home/<user>/.<packageName> But I'm still at a loss as to how I can
> find a users home directory from the rules makefile :(
>
> been trying to use ~/ and $XDG_CONFIG_HOME but I just end up with
> everything being installed in folders called "~" or "DG_CONFIG_HOME"

DON'T. Users' homedirs are off limits to package managers such as
dpkg. The application, when run, may install a file there, but the
rules script should not.


Regards,
Lars