ikiwiki/doc/bugs/aggregate_generates_long_filenames.mdwn

the [[plugins/aggregate]] plugin mashes the `title` of an aggregated post into a filename.  This results in long filenames.  I have hit a filesystem length limitation on several occasions.  Some (ab)uses of RSS, e.g., twitter,
generate long titles.  Especially once you throw escaping into the mix:

    $ ikiwiki --setup testsetup --aggregate --refresh
    failed to write ./test/lifestream/Hidden_Features_Of_Perl__44___PHP__44___Javascript__44___C__44___C++__44___C__35____44___Java__44___Ruby___46____46____46__._aggregated.ikiwiki-new: File name too long
    aggregation failed with code 9216
    $ echo $?
    25

It would also appear this abrubtly terminates aggregate processing (if not ikiwiki itself).  Only after moving my test repo to `/tmp` to shorten the filename did I see newer RSS feeds (from a totally different source) picked up.


-- [[Jon]]

> I have to wonder what filesystem you have there where 147 characters
> is a long filename. Ikiwiki already uses `POSIX::pathconf` on the srcdir
> to look up `_PC_NAME_MAX`
> to see if the filename is too long, and shortens it, so it seems
> that, in additional to having a rather antique long filename limit, your
> system also doesn't properly expose it via pathconf. Not sure what
> ikiwiki can do here. --[[Joey]]

>> This is an ext4 filesystem with default settings (which appears to mean
>> 256 bytes for pathnames).  Despite the error saying file name, it's
>> definitely a path issue since moving my test repo to `/tmp`from
>> `/home/jon/wd/mine/www` hides the problem. I note the following comment
>> in `aggregate.pm`:

		# Make sure that the file name isn't too long. 
		# NB: This doesn't check for path length limits.

>> I don't fully grok the aggregate source yet, but I wouldn't rule out
>> a bug in the path length checking, personally.  I'm happy to try and
>> find it myself though :) -- [[Jon]]

>>> Path length seems unlikely, since the max is 4096 there.
>>> --[[Joey]] 

>>>> Aggregate now used a "if it crashes, it must be too long" strategy.
>>>> [[done]] --[[Joey]]