Re: [gentoo-portage-dev] [PATCH 3/3] portage.dbapi.vartree: Support exclusions in INSTALL_MASK

[Zac Medico]

On 06/12/2016 02:31 AM, Michał Górny wrote:
> Dnia 12 czerwca 2016 11:20:36 CEST, Zac Medico <zmedico@g.o> napisał(a):
>> On 05/21/2016 11:56 PM, Michał Górny wrote:
>>> Allow INSTALL_MASK patterns to start with '-' to indicate that
>>> a specific match is to be excluded from being masked. In this case,
>>> the last matching pattern determines whether the file is actually
>>> filtered out or kept.
>>> ---
>>>  pym/portage/dbapi/vartree.py | 10 ++++++----
>>>  1 file changed, 6 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/pym/portage/dbapi/vartree.py
>> b/pym/portage/dbapi/vartree.py
>>> index 8e5ac43..d02d850 100644
>>> --- a/pym/portage/dbapi/vartree.py
>>> +++ b/pym/portage/dbapi/vartree.py
>>> @@ -3690,19 +3690,21 @@ class dblink(object):
>>>  	def _is_install_masked(self, relative_path):
>>>  		ret = False
>>>  		for pattern in self.settings.install_mask:
>>> +			# if pattern starts with -, possibly exclude this path
>>> +			pat_res = not pattern.startswith('-')
>>> +			if not pat_res:
>>> +				pattern = pattern[1:]
>>>  			# absolute path pattern
>>>  			if pattern.startswith('/'):
>>>  				# match either exact path or one of parent dirs
>>>  				# the latter is done via matching pattern/*
>>>  				if (fnmatch.fnmatch(relative_path, pattern[1:])
>>>  						or fnmatch.fnmatch(relative_path, pattern[1:] + '/*')):
>>> -					ret = True
>>> -					break
>>> +					ret = pat_res
>>>  			# filename
>>>  			else:
>>>  				if fnmatch.fnmatch(os.path.basename(relative_path), pattern):
>>> -					ret = True
>>> -					break
>>> +					ret = pat_res
>>>  		return ret
>>>
>>>  	def treewalk(self, srcroot, destroot, inforoot, myebuild,
>> cleanup=0,
>>>
>>
>> In order to implement this with pre-compiled patterns, we can use a
>> separate regular expression to represent all of the exclusions.
>
> That won't work since exclusive and inclusive patterns can be stacked, and for this to work they are applied in order.
>
> E.g. /usr/foo -/usr/foo/bar /usr/foo/bar/baz
>
> Should remove all foo subdirectories except for bar, and also baz inside bar.

Hmm, I suppose there could be an optimized implementation to handle
INSTALL_MASK settings where there are no such ordering constraints.
-- 
Thanks,
Zac