Re: [PATCH] Change attachment stamping to use stat st_mtime by default.

On 2026-08-20 12:29:57 +0200, Oswald Buddenhagen via Mutt-dev wrote:
> On Thu, Aug 20, 2026 at 10:54:23AM +0800, Kevin J. McCarthy wrote:
> > Recent Linux kernels have an issue where time() has a lower
> > granularity than the stat st_mtime of a file.
> > 
> the granularity is one second. st_mtime is a subset of st_mtim which has a
> higher granularity, but that's been the case for decades, at least on fs
> that actually support it.

st_mtim has been more precise for years, but it was not accurate.
Its accuracy has been improved (to match CLOCK_REALTIME?) in

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4e40eff0b5737c

(starting with the 6.13 kernel), which is the cause of this issue.

> > This can result in time() being earlier than the mtime of a file
> > just modified.
> > 
> it can't, as long as only the full seconds are compared.

It can (even if you take the nanoseconds of st_mtim into account
as they are non-negative[*]), as shown by the tests.

[*] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1144613#32

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