[Patch v4] lib: regexp matching in 'subject' and 'from'

[David Bremner]

Jani Nikula <jani at nikula.org> writes:

>
> Theoretically "/" is an acceptable character in message-ids [1]. Rare,
> unlikely, but acceptable. Searching for message-id's beginning with "/"
> would have to use regexps, which would break in all sorts of ways
> throughout the stack. I don't think there are handy alternatives to
> "/<regex>/", given the characters that are acceptable in message-ids,
> but this is something to think about.

Would telling the user to \ escape ( or double /) the initial / be good
enough there? This would disable regex processing.  I guess this goes
back to someone's earlier suggestion.  A third option would be to use
single quotes there ("id:'/foo'"), but that isn't really consistent with either Xapian
or usual regex conventions.

So I guess my favourite idea ATM is to use id:\/some/crazy/message-id
FWIW, I don't have any such message ids.

> For example, could the regexp matcher for message-ids first check if the
> "regexp" is a strict match with "/" and all, and accept those? This
> might be a reasonable workaround if it can be made to work.

We're building a query, so I think the equivalent is to make an OR, with
the exact match and the regex posting source. That could be done,
although I'm a bit uneasy about how this makes the syntax for id:
different, so id:/foo would be legit, but from:/foo would be an error.
Maybe the dwim-factor is worth it.

d