Re: mailbox path formatting feature

[Matti Aarnio <mea@nic.funet.fi>]

On Thu, Sep 09, 1999 at 01:34:46PM +0400, Eugene Crosser wrote:
> Matti and guys,
> 
> what do you think about the following feature.  If you specify a
> special new variable in zmailer.conf, it overrides MAILBOX variable
> and allows to specify the format of the path to the user's mailbox,
> that may include userid, homedir, PJW hash, domain etc.  Like this:

	How about, if "MAILBOX" variable has %-char in it, it
	will be interpreted in this manner.

	Because the PJW hash is not very good (non-uniform),
	I would add CRC32 hash there too.
	( I will separate the  crc32()  into separate routine, watch cvs.. )

	Also, some people are asking for qmail's "maildir",
	this could do that too, could it not ?

	For quite a while I have pondered about having some

		~/.mailbox

	file at which people could specify local processing rules,
	e.g. if they want the incoming email stored somehow
	specially, or ran thru e.g. procmail at reception, or ...
	A snafu is that we already have procmail, and repeating
	it all within 'mailbox' won't be very productive.
	( But certain usefullness could be achieved from telling
	  that "although generally email is coming thru procmail,
	  I want unfiltered feed into maildir!" without having to
	  use some piped program thru  .forward  file ... )

	... which reminds me, "pine" reads configuration files:
		pine.conf
		~/.pinerc
		pine.conf.fixed
	That is, first gives global defaults, second is what user
	can tune, and third enforces (sets/clears) some global values.

> # int fmtmbox(char *buf, int size, const char *format,
> #             const char *address, const struct passwd *pwd);
> #
> # format specifiers:
> #
> # %% - '%' alone
> # %u - userid
> # %U - long user name (userid if not supported)
> # %d - first element of domain name
> # %D - full domain name
> # %x - one-character derivate of PJW hash of userid
> # %X - two-character derivate of PJW hash of userid

	Hmm... No.    %x/%x/  should be equivalent to  %X
	Then we have "%X" free for other uses. (e.g. CRC32)

	Algorithm something like:

	/* That has is hardly ever zero, thus... */
	int hash = 0;

	for (;*fmt;++fmt) {
	  switch (*fmt) {
	  '%X':
		if (!hash) hash = crc32(username);
	  '%x':
		if (!hash) hash = pjwhash32(username);
		c = 'A' + hash % 26;
		hash /= 26;
		break;
	  }
	  *out++ = c;
	}

	You get the idea :)
	(Only one hash can be calculated per path.)

> # %h - userid's home directory
> # %d - least number guaranteening unique filename (for MH style boxes)
> # %D - the same padded by leading zeroes to fixed length
> # %(any other character) - substitute with "__" (two underscores)
> #
> # Examples:
> # "/var/mail/%u"               - standard mail directory
> # "/var/mail/%X/%u             - hashed directory
> # "%h/Mail/INBOX"              - mailbox in user's home
> # "/var/virtual/%D/mail/%X/%u" - hashed spool with virtual domain
> 
> I think that I could work out such a thing...
> 
> Eugene

-- 
/Matti Aarnio	<mea@nic.funet.fi>