On Fri, 28 Apr 2006, listrcv wrote:

> > Lots of things start failing when path names get longer than 256 
> > characters (or perhaps 1024). I think 256 is a POSIX limit.
> 
> How does Exim handle that?

Without searching the code, I can't be sure, but I don't think it does 
any checks itself. However, if it tries to create a directory and fails, 
delivery is deferred. I imagine the OS or file system will impose this 
limit and give an error when at attempt is made to exceed it.

> Well, if I got it right, the idea was that subsequent directories should 
> not have to be created before mail can be delivered to them. Having Exim 
> create them could eventually be exploited by supplying suitable content 
> to string expansions or to lookups, or even by putting such content into 
> mail.

Exim does not, and cannot, protect sysadmins against their own mistakes.
It's the sysadmin who creates the string expansions and presumably
controls the contents of lookups. Or am I misunderstanding what you are
saying?

Data from the mail in this connection is normally only $local_part and 
$local_part_suffix (or prefix), and the values of these are presumably 
constrained by the routers.

> Without finer grained control on directory creation, the only choices 
> then would be to either turn it off or to pre-create directories and 
> making use of the require_files option (as someone suggested). Or am I 
> mistaken?

There is some fine-grained control. Look at the create_file option and 
file_must_exist options. 

-- 
Philip Hazel            University of Cambridge Computing Service
Get the Exim 4 book:    http://www.uit.co.uk/exim-book

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