[apparmor] [patch] [2/9] Add strip_parenthesis() to regex.py

[Christian Boltz]

Hello,

Am Montag, 22. Februar 2016, 01:55:35 CET schrieb Kshitij Gupta:
> On Mon, Feb 22, 2016 at 1:07 AM, Kshitij Gupta wrote:
> > On Sun, Dec 27, 2015 at 8:34 PM, Christian Boltz wrote:
> >> some dbus rule conditionals come with optional parenthesis. Instead
> >> of making the regex even more complicated, use a small function to
> >> strip those parenthesis.
> >> 
> >> Also add some tests for strip_parenthesis() to test-regex.py.
> >> 
> >> 
> >> [ 53-add-strip_parenthesis.diff ]
> >> 
> >> === modified file ./utils/apparmor/regex.py
> >> --- utils/apparmor/regex.py     2015-12-21 00:13:57.207799592 +0100
> >> +++ utils/apparmor/regex.py     2015-12-24 01:19:47.916978461 +0100
> >> @@ -128,6 +128,15 @@
> >> 
> >>      return matches.group('magicpath')
> >> 
> >> +def strip_parenthesis(data):
> >> +    '''strips parenthesis from the given string and returns the
> >> strip()ped result.
> >> +       The parenthesis must be the first and last char, otherwise
> >> they won't be removed.
> >> +       Even if no parenthesis get removed, the result will be
> >> strip()ped. +       '''
> >> +    if data[0] + data[-1] == '()':
> >> +        return data[1:-1].strip()
> >> +    else:
> >> +        return data.strip()
> > 
> > Might be useful to do the data.strip() before the "data[0] +
> > data[-1] == '()'" check, that way you don't miss on something like
> > '(hey) '. This is because there doesn't seem to be a strong
> > assumption that the data will already be stripped coz we return
> > data.strip()

I'm following the strip_quotes() behaviour in not stripping space before 
removing parenthesis, and I'm quite sure the regexes that "feed" 
strip_parenthesis() make sure there's no whitespace around.
See for example RE_ACCESS_KEYWORDS and RE_FLAG in apparmor/rule/dbus.py 
(from the dbus patch series, not in bzr yet)

OTOH, whitespace inside parenthesis is allowed, so it makes sense to 
strip() it after removing the parenthesis.

> > Also, I don't see any harm in having the .strip before the check.

In theory it could "hide" whitespace included by (IMHO) broken regexes, 
with all sort of follow-up problems. I hope not-removed parenthesis (if 
the string starts or ends with whitespace) are more visible and easier 
to find, so I prefer not to strip() whe whole string.

> >>  def strip_quotes(data):
> >>      if data[0] + data[-1] == '""':
> >> === modified file ./utils/test/test-regex_matches.py
...


Regards,

Christian Boltz
-- 
> Ich hätte auch nie geglaubt, das es 10 Minuten dauern kann, bis jemand
> ohne Fehler einmal ein  lspci -v  fehlerfrei eingegeben hat.
Hast Du auch erwähnt, daß man anschließend die RETURN-Taste drücken muß?
                  [> Torsten Hallmann und Bernd Brodesser in suse-linux]
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