Re: get rid of getpwent? (Was: cygwin-1.7.28 getpwent header declaration changes ?)

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

On Feb 11 19:06, Eric Blake wrote:
> On 02/11/2014 05:06 PM, Warren Young wrote:
> > On 2/11/2014 16:25, David Stacey wrote:
> >> getpwent() is called in three different places.
> > 
> > To those of you who have investigated these code paths: do any of them
> > look like they couldn't be replaced by getpwnam() or other calls that
> > would let cygwin1.dll do single-record AD/SAM lookups, rather than
> > whole-table/tree scans?
> > 
> > That is, do any of these programs really need to visit every record in
> > /etc/passwd?
> 
> libreadline wants to know how to tab-complete ~foo; to do that, it has
> to find all usernames beginning with foo.  How would you do that without
> visiting every single record?

This seems to be the major usage of getpwent these days.  The question
is, how bad is it if only a handful entries, or even only a single one
(of oneself) show up?

Either way, implementing a full getpwent requires to return the local
users, the users of the primary domain, and the users of all trusted
domains.  I know of domains with 200K users and there are probably
bigger ones.  How long should a search take when a user presses <TAB>
after the ~?  And then, shall the process running the getpwent actually
cache all of them?  This seems really excessive.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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