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Re: Freeze exception for resolv.conf parser changes
- From: Carlos O'Donell <carlos at redhat dot com>
- To: Florian Weimer <fweimer at redhat dot com>, Siddhesh Poyarekar <siddhesh at gotplt dot org>
- Cc: GNU C Library <libc-alpha at sourceware dot org>
- Date: Fri, 30 Jun 2017 16:26:18 -0400
- Subject: Re: Freeze exception for resolv.conf parser changes
- Authentication-results: sourceware.org; auth=none
- References: <email@example.com>
On 06/30/2017 03:45 PM, Florian Weimer wrote:
> I've just posted my resolv.conf changes. They address two long-standing
> problems with the stub resolver: automatic reloading of struct
> resolv_conf, and the hard search list limit (6 domains). Both issues
> have seen quite a bit of user interest over the years.
> I think these patches are ready to go in now. The whole construction is
> a bit baroque, but that's the price we pay for ABI compatibility and
> support for applications which patch _res today.
> But I would like to continue working on this during the first week of
> the freeze. I see the following five immediate improvements:
> * More test coverage. (I tested resolv.conf reloading only manually.)
> * Lazy allocation of the main state in resolv/resolv_conf.c, to conserve
> data segment space for programs which do not use the stub resolver.
> * Eliminate some locking in resolv/resolv_conf.c.
> * Use a free list for indexes into the resolv_conf array (speeds
> up _res object allocation/resolv_conf attachment).
> * Reimplement the libresolv compat gethostname on top of NSS.
> I think these changes are low risk.
> There are some additional to-do items, but I don't think they need to
> get into the release.
> * Clean up the nssocks array (we do not need it).
> * Support arbitrarily many name servers.
> * Lazily initialize _res on first access. (Then if *_res is NULL,
> the application obviously has not patched _res.)
> * Lazily allocate _res (like global-dynamic TLS). This frees about ~500
> bytes in the TCB.
I have added this to the release blockers. I think it's gone on for too long
that we don't have reloading /etc/resolv.conf, we get asked about it all the
time and we have promised our users we would tackle this issue.