Bug#913274: Incorrectly parsing whitespace in Sources.iter_paragraphs
stuart at debian.org
Wed Nov 14 05:17:04 GMT 2018
> I've narrowed down where the issue occurs. It happens when passing the
> contents rather than the file handle to iter_paragraphs:
> ~# ipython3
> Python 3.5.3 (default, Jan 19 2017, 14:11:04)
> Type "copyright", "credits" or "license" for more information.
> IPython 5.1.0 -- An enhanced Interactive Python.
> ? -> Introduction and overview of IPython's features.
> %quickref -> Quick reference.
> help -> Python's own help system.
> object? -> Details about 'object', use 'object??' for extra details.
> In : from debian.deb822 import Packages
> In : with open('Packages') as fh:
> ...: for p in Packages.iter_paragraphs(fh.read()):
> ...: if 'version' not in p:
> ...: print(p)
> Homepage: https://code.visualstudio.com/
> Passing the contents does the correct thing in all other cases, so not
> sure why it would be having an issue with this?
TagFile only accepts filehandles, not static data:
In deb822.py there is a function _is_real_file() and that is used so that
python-apt's TagFile is only invoked on filehandles and not on text data,
diverting to the in-built parser when TagFile cannot be used.
BTW if you are read()ing so that you can deal with the compressed Pacakges.gz,
TagFile can handle on-the-fly decompression.
In : from debian.deb822 import Packages
In : with open('Packages.gz') as fh:
...: for p in Packages.iter_paragraphs(fh):
...: if 'version' not in p:
(wild guess as to why you might be doing this!)
I've been thinking that in cases where iter_paragraphs was called with
use_apt_pkg=True and then apt_pkg is not used contrary to what was requested,
iter_paragraphs should generate a warning. That risks becoming noisy in a way
that is not desirable, but also perhaps gets us away from this ambiguous
behaviour where the use_apt_pkg setting has been ignored.
I wonder what the likelihood is that introducing a warning would break someone
else's code? (It would break an autopkgtest, for instance, by writing to
Stuart Prescott http://www.nanonanonano.net/ stuart at nanonanonano.net
Debian Developer http://www.debian.org/ stuart at debian.org
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